Hydrological Analysis for Masang-2 HEPP

Transcription

1 Part 16 Hydrological Analysis for Masang-2 HEPP

2 PART 16 HYDROLOGICAL ANALYSIS FOR MASANG-2 HEPP 16.1 METEOROLOGY AND HYDROLOGY Meteorological Records and Hydrological Records are collected from Meteorological Climatological and Geophysical Agency (Badan Meteorologi Klimatologi dan Geofisika: BMKG), Research Institute for Water Resources Development under Ministry of Public Works (Pusat Penelitian dan Pengembangan Sumber Daya Air: PUSAIR, formerly DPMA), and engineering reports on various hydropower development projects. The location map of the stations is shown in Figure 1. The availability of data is summarized in Figure 2 and Figure 3. The catchment area of Masang-2 HEPP intake weir site is shown in Figure METEOROLOGICAL DATA Climatic data such as air temperature, relative humidity, wind velocity, sunshine duration have been observed at the Tabing-Padang station, which is collected from BMKG. Pan-evaporation has been observed at the Lubuk Sikaping and the Tanjung Pati stations. Pan-evaporation data is collected from Masang-3 HEPP report. The variation of principal climatic data at the Tabing-Padang station, the Tanjung Pati station and the Lubuk Sikaping station is shown in Figure 5. (1) Air Temperature Table 1 shows the monthly mean air temperature at the Tabing-Padang station. The average monthly mean air temperature at the Tabing-Padang station in the period of 1971 to 22 is summarized below. Unit: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean As seen, the mean annual air temperature at the Tabing-Padang station is 26.1ºC on an average. There is a slight seasonal change ranging 25.7ºC in August or September to 26.6ºC in May. (2) Relative Humidity Table 2 shows the monthly mean relative humidity at the Tabing-Padang station. The average monthly relative humidity at the Tabing-Padang station in the period of 1971 to JICA Project for the Master Plan Study of 16-1 August, 211

3 22 is summarized below. Unit: % Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean As well as the monthly pattern of mean air temperature, there is no significant change of relative humidity throughout the year. The annual mean relative humidity in the period of at the Tabing-Padang station is 82.5 % and there is a slight seasonal change ranging from 81.1% in January to 84.6 % in November. (3) Sunshine Duration Table 3 shows the monthly mean sunshine duration at the Tabing-Padang station. The average monthly mean sunshine duration at the Tabing-Padang station in the period of 1971 to 22 is summarized below. Unit: % Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean As seen, the mean annual sunshine duration at the Tabing-Padang station is 52.7 % on an average. The maximum duration of 61.7 % and the minimum one of 4.4 % occur in June and November, respectively. Sunshine duration generally decreases with an increase of rainfall. The highest sunshine duration therefore occurs in June in the dry season. (4) Wind Velocity Table 4 shows the monthly mean wind velocity at the Tabing-Padang station. The average monthly mean wind velocity at the Tabing-Padang station in the period of 1971 to 22 is summarized below. Unit: m/sec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean Mean annual wind velocity at the Tabing-Padang station is 1.1 m/sec ranging from.9m/sec in June and 1.3 m/sec in January, February or March. The wind velocity records collected from Masang-3 HEPP reports in the period of 1971 to 1989 are around 1 m/sec, but the others collected from BMKG in the period of 199 to 22 are around.1 m/sec. (5) Evaporation Pan evaporation records are available at the Lubuk Sikaping station and the Tanjung Pati station. The pan evaporation records at both stations are summarized on monthly basis as shown in Table 5. The average monthly mean pan evaporation at the Lubuk Sikaping and the Tanjung Pati stations is summarized below. JICA Project for the Master Plan Study of 16-2 August, 211

4 Station Name: Lubuk Sukaping ( ) Unit: mm/day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean Station Name: Tanjung Pati ( ) Unit: mm/day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean The ruling factors of pan evaporation may be air temperature and relative humidity, namely evaporation rate varies season to season following to mainly the variation of humidity. As seen in the above table, the seasonal variation of pan evaporation is generally small throughout the year, because there is no great seasonal variation of relative humidity RAINFALL DATA There are 13 rainfall gauging stations in and around the Masang River basin. The location map of these stations is shown in Figure 1. Also the data availability at these stations is shown in Figure 2. The rainfall gauging stations are operated and maintained under BMKG. Monthly rainfall records are collected in Masang-3 HEPP and HPPS2, besides daily rainfall records are collected from BMKG in this study. PLN formerly had own hydrological observation network (PLN-LMK Observation Network). Currently most of these stations have broken down, after regional office of PLN took responsibility for maintenance which the central office of PLN had taken. (1) Monthly Rainfall Data The monthly mean rainfall records are collected at 13 stations as presented in Table 6 to Table 18. The monthly distributions of mean annual rainfall are illustrated below. Rainfall(mm) Maninjau: 3,199 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec JICA Project for the Master Plan Study of 16-3 August, 211

5 Rainfall(mm) Limau Purut: 3,491 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) Padang Panjang: 3,76 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) Rainfall(mm) Bukit Tinggi: 2,21 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Baso: 2,12 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec JICA Project for the Master Plan Study of 16-4 August, 211

6 Rainfall(mm) Padang Mangatas: 2,45 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) Rainfall(mm) Rainfall(mm) Payakumbuh: 2,181 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Koto Tinggi: 2,638 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Suliki: 2,44 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec JICA Project for the Master Plan Study of 16-5 August, 211

7 Rainfall(mm) Rainfall(mm) Rainfall(mm) Rainfall(mm) Kota Baharu: 2,828 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Bonjol: 4,613 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jambak: 3,797 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Lubuk Sikaping: 3,76 mm ( ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec As seen above, the annual mean rainfall at these stations ranges from 2, mm to 4,6 mm per year. It might be said that there exists little seasonality in the Masang River basin receiving rainfalls throughout the year. (2) Hourly Rainfall Records Hourly rainfall records are available at the Gunung Melintang, Maninjau, Sungai Talang JICA Project for the Master Plan Study of 16-6 August, 211

8 Barat, Solok Bio-Bio, Muara Paiti, Patir, Puar Datar and Halaban Dua rainfall gauging stations. The location map of the stations is illustrated in Figure 6. Hourly rainfall records are collected to determine the rainfall pattern for the flood analysis. Hourly rainfall records of more than 5 mm were selected for estimating the characteristics of relatively heavy rainfall. The list of selected hourly rainfall records are enumerated in Table 19 and illustrated in Figure 7. The accumulated hourly rainfall curves are constructed as shown in Figure 7. From these curves, the following findings on storm rainfall characteristics are drawn. The duration of storm rainfall is less than 6 hours. Most of the total amount of rainfall occurs in antecedent 3 hours RUNOFF RECORDS (1) Water Level Gauging Station (AWLR Station) Only one water level gauging station has been installed in the Masang River basin. The station name is the Sipisang AWLR station located in the north of Palembayan town. The catchment area of the station is described as 458 km 2 in the records from 1975 to 1992, and as km 2 in the records from 1993to 28. On this study, the catchment area of the station is measured as 475km 2 based on 1:5, scale map. Besides, the catchment area of Masang-2 HEPP intake weir site is measured as 443km 2. The Sipisang AWLR station is operated by the regional office of the River Bureau under the Ministry of Public Works (Balai Pengendalian Sumber Daya Air: BPSDA). (2) Runoff Records The daily runoff records are collected from PUSAIR in Bandung and the daily water level records are collected from BPSDA in Bukit Tinggi. The daily runoff records are available from 1975 to 28 except in 1988, 1989, 1994, 22, 23 and 24. The monthly mean runoff at the Sipisang AWLR station is presented in Table 2. The daily hydrographs are illustrated in Figure 8 to Figure 14, and the daily water level graphs are illustrated in Figure 15 to Figure 16. The average monthly mean runoff in the period of is summarized below. Station Name: Sipisang ( ) Unit: m3/s Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean As seen, the annual mean runoff at the Sipisang AWLR station is 21.9m 3 /s or 1,455mm in JICA Project for the Master Plan Study of 16-7 August, 211

9 terms of the annual runoff depth, which is computed by dividing the annual accumulated runoff volume by the catchment area of the gauging station LOWFLOW ANALYSIS (1) General Approach The continuous long-term runoff data for a time period of more than 2 years at the proposed intake weir site is normally required for evaluating an optimum development scale of the project through power output computation. Further, it is highly expected that the runoff data should be of high accuracy because measurement on economic viability of project is highly dependent on the reliability of available runoff records. On the Masang-2 HEPP, daily runoff records are required because the type of hydropower development scheme is runoff type. As described in the previous chapter, the daily runoff records are available from 1975 to 28 except in 1988, 1989, 1994, 22, 23 and 24. Furthermore, the remaining observation years still include data-missing periods. Therefore, it is necessary to supplement the runoff records at the Sipisang station by infilling of missing data. On the other hand, the monthly basin mean rainfall at the Sipisang station can be estimated for the period between 1973 and Thus the runoff data at the Sipisang station can be supplemented and expanded for the period of 1973 to 1993 by constructing a rainfall-runoff simulation model. Along this line, the Tank Model Method is applied in this study as a rainfall-runoff model, the model parameters of which are calibrated by using rainfall and runoff records available in the period of 1982 to Firstly, the reliability of the available runoff records at the Sipisang station for using calibration is evaluated by means of runoff coefficient and annual rainfall loss. Then lowflow analysis by the Tank Model Method is carried out to simulate 21-year long-term monthly runoff data at the Sipisang station. Finally the daily runoff data at the Masang-2 intake weir site is estimated with 14-year simulated monthly data and 7-year observed daily data. The outline of lowflow analysis is described below. JICA Project for the Master Plan Study of 16-8 August, 211

10 (2) Estimation of Missing Data The observed rainfall records at all of the selected stations include several data interruptions. For the purpose of supplementing the missing rainfall records, the simple regression analysis on the monthly basis are carried out among the selected stations. Missing data at a station is supplemented by another station with linear regression equation which has the highest correlation coefficient. The number of data and correlation coefficient and slopes of linear regression equation is tabulated in Table 21. (3) Test of Consistency of Rainfall Records The method of testing rainfall records for consistency is the double-mass curve technique. Double-mass analysis tests the consistency of the record at a station by comparing its accumulated annual or seasonal precipitation with the concurrent accumulated values of mean precipitation for a group of surrounding stations. The corrected rainfall is determined by the following equation. P CX = PX ( M C / M a ) where, P CX : Corrected rainfall at any time period at station x (mm) P X : Original recorded rainfall at any time period at station x (mm) M C : Corrected slope of the double-mass curve M : Original slope of the double-mass curve a JICA Project for the Master Plan Study of 16-9 August, 211

11 The double-mass curves are presented in Figure 17. As seen, the monthly rainfall records at the following stations are adjusted for the following periods. Maninjau Station: 1979 to 1993 Suliki Station: 1988 to 1993 (4) Estimation of Basin Mean Rainfall at the Sipisang AWLR Station The basin mean rainfall at the Sipisang AWLR station is estimated by applying the Thiessen Method using the corrected data. The records of selected rainfall gauging stations are divided in two periods considering data availability. Case1 (1973 to 1986): Maninjau, Koto Tinggi, Suliki Case2 (1987 to 1993): Koto Tinggi, Suliki, Jambak The tables below show the computed Thiessen coefficients for estimating basin mean rainfall at the the Sipisang AWLR station. Thiessen polygon is illustrated in Figure 18. Case1 ( ) Maninjau Koto Tinggi Suliki Case2 (1987 to 1993) Koto Tinggi Suliki Jambak The estimated monthly basin mean rainfall at the Sipisang AWLR station is presented in Table 22. The estimated annual basin mean rainfall is 2,57mm. (5) Evaluation of Runoff Records at the Sipisang AWLR Station The Sipisang AWLR station is selected as a key stream gauge station for predicting the long-term runoff at the proposed Masang-2 intake weir site, because it is the only gauge located in the Masang River. The evaluated period of runoff records is determined to be 5 years from 1982 to 1986, because both rainfall and runoff records are available in this period for calibration of Tank Model parameters. 1) Relationship between Annual Basin Mean Rainfall and Annual Runoff Depth at the Sipisang AWLR Station The annual basin mean rainfall at the Sipisang AWLR station is estimated for the period of 1982 to On the other hand, the annual runoff depth of Masang River at the Sipisang station is computed by dividing the annual runoff volume by its drainage area of 475 km 2 for the same period as above. The established relationship between annual basin mean rainfall and annual runoff depth at JICA Project for the Master Plan Study of 16-1 August, 211

12 the Sipisang station is as follows. Besides, the relationship is plotted in Figure 19. Year Annual Rainfall (mm) Annual Runoff Depth Annual Rainfall Loss Runoff Coefficient ,27 1, ,43 1,253 1, ,314 1,233 1, ,339 1,318 2, ,615 1,449 1, ,29 1,45 1, ,3 1,326 1, ,27 2, Average 2,749 1,438 1, The difference between the annual basin mean rainfall and annual runoff depth is the so-called evapotranspiration loss or annual rainfall loss. The annual rainfall loss is analyzed for major rivers in Sumatra in HPPS2 as presented in Table 23 and illustrated in Figure 2. It is therefore found that the annual rainfall loss normally falls in a range of 7 to 1,5 mm a year which varies according to altitude, natural vegetation, seasonal distribution of rainfall, etc. As seen above, the rainfall loss at the Sipisang station varies from 8mm to 2,mm. From the hydrological point of view, the rainfall loss usually varies in a small range. Therefore it is estimated that rainfall data or runoff data has some errors. The basin mean rainfall is adjusted based on the following consideration. The annual runoff depth is likely to be constant rather than the basin mean rainfall, with small variations of 1,2 to 1,5 mm. The observed record in 1993 is eliminated because it might contain errors due to malfunctioning of water level recorder. Maninjau, Koto Tinggi, Suliki, Jambak rainfall gauging stations which are used for estimating basin mean rainfall are located outside the Masang River basin. This fact implies that the estimated basin mean rainfall might inevitably contain some error to some extent. The estimated annual basin mean rainfall in 1976, 1984 and 1991 are thus adjusted such that the annual rainfall loss becomes 1,251mm, which corresponds to the mean annual rainfall loss in 1982, 1983, 1985 and The adjusted relationship between annual basin mean rainfall and annual runoff depth at the Sipisang station is given below. JICA Project for the Master Plan Study of August, 211

13 Year Annual Rainfall (mm) Annual Runoff Depth Annual Rainfall Loss Runoff Coefficient ,626 1,375 1, ,43 1,253 1, ,314 1,233 1, ,568 1,318 1, ,615 1,449 1, ,29 1,45 1, ,577 1,326 1, Average 2,594 1,343 1, ) Double Mass Curve Analysis Based on the adjusted annual basin mean rainfall and annual runoff depth at the Sipisang station, the double mass curve is constructed as given below. Accumulated Runoff Depth (mm) 1, 5, , 1, 15, 2, Accumulated Basin Mean Rainfall (mm) As shown above, the annual basin mean rainfall and annual runoff depth are plotted on a straight line, satisfactorily showing the hydrological consistency ready for Tank model analysis to be discussed in the next section. (6) Tank Model 1) Concept of Tank Model Method The Tank Model simulation method is widely applied for estimating river runoff from rainfall data. The Tank Model Method has been successfully applied for low-flow analysis in various water resources development projects in Indonesia. Basic concept of Tank Model The basic idea of Tank Model is very simple. Consider a tank having a hole at the bottom and another hole at the side as illustrated below. JICA Project for the Master Plan Study of August, 211

14 When the tank is filled with water, the water will be released from the holes as shown in the above. In the tank model simulation, it is considered that the water released from the side hole corresponds to runoff from a stream, and the water from the bottom hole goes into the ground water zone. The depth of water released from a hole is given by the following tank equation. Q = α H where, Q : Runoff depth of released water (mm) α : Coefficient of hole H : Water depth above the hole (mm) Applied Tank Model For the purpose of natural runoff simulation, four by four (4 4) tanks combined in series are used as shown in Figure 21. The top tank receives the rainfall as inflow to the tank, while the tanks below get the supply from the bottom holes of the tank directory above. The aggregated outflow from all the side holes of the tanks constitutes the inflow in the river course. To effectively trace dry conditions in the basin, several modifications are made on the basic model. The model is firstly facilitated with a structure to simulate the moisture content in the top tank. This sub-model is composed of two moisture-bearing zones, which contain moisture up to the capacities of saturation. Between the two zones, the water transfers as expressed below. T 2 = TC( XP / PS XS / SS) where, T 2 : Transfer of moisture between primary and secondary zones (if positive, transfer occurs from primary to secondary, and vice versa) TC : Constant JICA Project for the Master Plan Study of August, 211

15 XP : Primary soil moisture depth PS : Primary soil moisture capacity XS : Secondary soil moisture depth SS : Secondary soil moisture capacity When the primary soil moisture is not saturated and there is free water in lower tanks, the water goes up by capillary action so as to fill the primary soil moisture with the transfer speed T1 as given below. T1 = TB(1 XP / PS) where, T 1 : Transfer of the water from lower tank with capillary action TB : Constant There are many tank model parameters such as hole coefficients of each tank, and height of side holes of each tank. These parameters cannot be determined mathematically. Therefore, these parameters are subject to determination through trial-and-error calculations comparing the calculated runoff with the actually observed runoff. 2) Input Data for Calibration Model The applied model and simulation condition for calibration are given below. The period for calibration set from 1982 to 1986 because there are continuously rainfall records and runoff records. Number of Tanks 4 4 Calculation Time Interval 1 month Calculation Period 1982 to 1986 Observed Runoff at Sipisang Station 1982 to 1986 Basin Mean Rainfall at Sipisang Station 1982 to 1986 Monthly Average Evaporation at Lubuk Sikaping 1979 to 1985 The pan evaporation record at the Lubuk Sikaping station is applied. The pan coefficient of.7 is applied for estimating evapotranspiration in the basin. The average monthly pan evaporation is given below. Station Name: Lubuk Sukaping ( ) Unit: mm/day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean ) Calibration Results Through several trial-and-error calculations, the best coincidence between the simulated and observed runoff at the Sipisang station is obtained under the tank parameters as follows. JICA Project for the Master Plan Study of August, 211

16 Hole Coefficient Height of Hole (mm) β α1 α2 H1 H2 Tank Tank Tank Tank Both observed and simulated hydrographs are shown in Figure 22. These hydrographs show that the simulated runoff satisfactorily represents the observed low-flow-season runoff. Furthermore, the consistency of the simulated runoff is examined by the comparison of flow duration curves constructed on the basis of the observed and simulated runoff. The flow duration curve for the runoff is drawn by arranging the discharges in descending order and assigning probabilities to each discharge, as illustrated in Figure 23. Both flow duration curves coincide with each other, especially in the lowflow period. The error of the estimated runoff over 4 % in probability varies between.4 % and 4.2 %. In addition to the above, the rainfall-runoff relationship of the simulated runoff is examined compared with the observed runoff as summarized below. Annual Annual Runoff Depth Annual Rainfall Loss Rainfall (mm) (mm) Runoff Coefficient Year (mm) Observed Simulated Observed Simulated Observed Simulated ,43 1,254 1,23 1,177 1, ,314 1,233 1,143 1,81 1, ,635 1,314 1,241 1,321 1, ,615 1,449 1,4 1,166 1, ,29 1,45 1,697 1,579 1, Average 2,65 1,34 1,337 1,265 1, As seen above, the average runoff coefficient and rainfall loss of the simulated runoff are derived to be.51 and 1,268 mm, respectively. On the other hand, hydrological indices of the observed runoff at the Sipisang station are.52 and 1,265 mm. These derived hydrological indices are judged to be in the hydrologically reasonable range. (6) Prediction of the Long-Term Runoff at the Sipisang AWLR Station The tank model with the calibrated parameters in the above is applied to generate the monthly runoff at the Sipisang station dating back to the period of 1973 to 1993 by use of the estimated monthly basin mean rainfall. The simulation results are summarized in Figure 24. The rainfall-runoff relationship of simulated runoff is summarized below. JICA Project for the Master Plan Study of August, 211

17 Year Annual Rainfall (mm) Annual Runoff Depth (mm) Annual Rainfall Loss (mm) Runoff Coefficient Observed Simulated Observed Simulated Observed Simulated ,213-1,188-1, ,622-1,255-1, , ,28 1, , ,215-1,1-1, ,23-1,71-1, , , , , ,797-1,43-1, ,43 1,254 1,377 1,177 1, ,314 1,233 1,159 1,81 1, ,635 1,314 1,245 1,321 1, ,615 1,449 1,41 1,166 1, ,29 1,45 1,697 1,579 1, ,674-1,41-1, ,231-1, , , ,516-1,184-1, ,3 1,326 1,538 1,74 1, ,874-1,821-1, ,27-1,646-1, Average 2,474-1,251-1, As seen in the table, the average runoff coefficient and rainfall loss of the simulated runoff are derived to be.5 and 1,222 mm, respectively. These hydrological indices are judged to be within the hydrological reasonable range. The monthly runoff data for the flow duration curve is consisted of 7-year observed monthly runoff in 1976, 1982 to 1986 and 1991, and of 14-year simulated monthly runoff in remaining period from 1773 to The flow duration curve for the 21-year runoff is drawn by arranging the discharges in descending order and assigning probabilities to each discharge. The flow duration curve of the observed and simulated runoff is shown in Figure 25. (7) Daily Flow Duration Curve For Masang-2 HEPP, daily runoff data is required for power output computation because the type of scheme is runoff type. Nevertheless, it is difficult to collect long-term daily rainfall and runoff data in Masang River basin and the monthly runoff records are supplemented and extended with Tank Model method. So the combination of daily observed runoff and simulated monthly runoff is used for setting the daily flow duration curve. The value of simulated monthly runoff data is regarded as simulated daily runoff in same amount. The condition of data is summarized below. JICA Project for the Master Plan Study of August, 211

18 Time Interval Daily Observed Daily Runoff 1976, 1982 to 1986, 1991 Simulated Monthly Runoff 1973 to 1975, 1977 to 1981, 1987 to 199, 1992, 1993 (8) Long-Term Runoff at the Masang-2 Intake Weir Site The long-term daily runoff at Masang-2 intake weir site for 21 years in the period of 1973 to 1993 is estimated from the predicted long-term daily runoff at the Sipisang station by using the following equation. The flow duration curve as shown in Figure 26, is drawn by arranging the discharges in descending order and assigning probabilities to each discharge. Q D = QW ( AD / AW ) where, Q D : Runoff at Masang-2 intake weir site (m 3 /sec) Q W : Runoff at Sipisang AWLR station (m 3 /sec) A D : Catchment area at Masang-2 intake weir site (=443km 2 ) A : Catchment area at Sipisang AWLR station (=475km 2 ) W (9) Water Level Observation and Discharge Measurement The field investigation of 3 month water level observation and 3 times discharge measurement was carried out from 21 October 6 th to 211 January 7 th by the sub-contractor. Location of the observation is at the Masang-2 intake weir site (St.1) and the Sipisang AWLR station (St.2). The location map of observation is shown in Figure 27. H-Q rating curve is established on the basis of observed water level and discharge, and hydrograph is established on the basis of observed water level and H-Q rating curve. Hydrograph is illustrated in Figure 28 and H-Q plot is shown in Figure 29. Consequently, the average water level is.75m and the average runoff is m 3 /s calculated with H-Q rating curve. The Equation of H-Q rating curve is given below. Q = ( H +.6) 2 where, Q : Runoff (m 3 /sec) H : Water level (m) The observed average runoff is about 15% of probability on the duration curve shown in Figure FLOOD ANALYSIS (1) General Approach Flood analysis is carried out to estimate the probable floods with various return periods as well as the probable maximum flood (PMF) at the Masang-2 intake weir site which are JICA Project for the Master Plan Study of August, 211

19 basically required for design of spillway and diversion facilities, and determination of dam height. For estimating the probable floods, the unit hydrograph method is applied, which synthesizes the various probable runoff hydrographs from the probable basin mean rainfalls based on the relationship between unit of basin mean rainfall and its runoff, that is the so-called unit hydrograph. It is generally agreed that the unit hydrograph method is applied for catchment areas less than 3, km 2. In this study, the Soil Conservation Service (SCS) unit hydrograph, which is empirically developed in USA Department of the Interior is used, because no hourly flood hydrograph is available at the Sipisang AWLR station to construct the unit hydrograph. The general approach of flood analysis is outlined below. (2) Rainfall Analysis 1) Depth-Area-Duration (DAD) Analysis DAD analysis is carried out to examine the following relationships. Relationship between rainfall depth and duration (DD Analysis) Relationship between rainfall depth and area (DA Analysis) JICA Project for the Master Plan Study of August, 211

20 a) Depth-Duration (DD) Analysis Generally, heavy rainfall occurs intensively in a short duration and sporadically in a limited area. Figure 7 shows the accumulated hourly rainfall curves of selected rain storms at the stations located around the Masang River basin. Hourly rainfall records exceeding 5 mm within 12 hours were selected for estimating the hourly rainfall hyetograph of heavy storm rainfall which might cause flood. The rainfall duration of selected 63-storm rainfall is arranged as histogram in Figure 3. Among the storm rainfalls bigger than 5mm, 6-hour of rainfall duration covers 63% of all. Besides, 6-hour of rainfall duration covers 8% of all among the storm rainfalls bigger than 1mm. So, the design rainfall duration time is estimated as 6-hour, which represents the characteristics of the storm rainfalls in Masang River basin. 4 of selected 63-storm rainfall have smaller duration time than 6-hours. The average of the 4 storm rainfalls is estimated as the design rainfall pattern. The accumulated hourly rainfall curves and the design rainfall curve are presented in Figure 31. The design distribution of hourly rainfall is shown below. Time (hour) Cumulative Rainfall Depth % 47% 78% 87% 95% 99% 1% Incremental Rainfall Depth % 47% 31% 9% 8% 4% 1% b) Depth-Area (DA) Analysis Generally, heavy rainfall occurs intensively in a short duration and sporadically in a limited area. Therefore the average depth of storm rainfall (basin mean rainfall) is likely to be smaller than the point depth of storm rainfall. In general, relation between point rainfall depth and average area is expressed by an exponential equation given by the following equation. P b n = P exp[ ka ] where, P b : Average rainfall depth over an area A (mm) P : Maximum point rainfall at the storm center (mm) A : Area in question (km 2 ) k, n : Constants for a given area The above equation is the so-called Horton s Equation. Constants k and n usually vary according to the given rainfall duration such as 1 hour, 6 hours, 12 hours, 1 day, etc. These constants are to be obtained through rainfall analysis based on the isohyetal maps of various major rain storms occurred in the river basin in question. However, the exact determination of P is practically impossible, because it is very unlikely that the rain storm center JICA Project for the Master Plan Study of August, 211

21 coincides with a rainfall gauging station. To estimate the basin mean rainfall from the point rainfall, the area reduction factor showing the ratio of basin mean rainfall to point rainfall is introduced as expressed below. P b = f a P where, P b : Basin mean rainfall (mm) P : Point rainfall (mm) f : Area reduction factor a If the Horton s equation is applied, the area reduction factor under the given rainfall duration is given by the following equation. f a = exp[ ka n ] However the available rain storm records in the Masang River basin are insufficient for reliable determination of the area reduction factor. The preliminary estimation of the design area reduction factor is carried out based on the following three approaches. Firstly, the area reduction factor is estimated as.63 under the catchment area of 443 km 2 for the Masang-2 intake weir site by applying the Horton s equation assuming that constants of k and n are.1 and.25, respectively. These constants have been widely and empirically applied in tropical rain forest area. A 443 (km2) k.1 n.25 fa.63 Secondly, the estimated design area reduction factors are examined in several other projects. The following design area reduction factors are based on the rainfall analysis using the observed rain storm records. Project Name Catchment Area Area Reduction (km2) Factor Besai HEPP (D/D in 199) Malea HEPP (F/S in 1984) 1, Tampur-1 HEPP (F/S in 1984) 2,.4 Musi HEPP (F/S in 1984) Cibuni-3 (F/S in 1984) 1,.41 Masang-3 HEPP (Pre F/S in 1999) Thirdly, the relation between the daily point rainfall and the daily basin mean rainfall around the Masang River basin is analyzed to estimate the area reduction factor of the river basin. The selected rainfall stations are the Payakumbuh and Maninjau stations. A basin mean JICA Project for the Master Plan Study of 16-2 August, 211

22 rainfall derives from an arithmetic average of an annual maximum daily rainfall of a target station and daily rainfall of another station at the same day. The average of ratios between basin mean rainfalls and annual maximum daily rainfalls of target stations is estimated as the area reduction factor. The list of rainfall is presented in Table 24 and plotted on Figure 32. Usually, it is considered that the rainfall intensity in hyetal areas increases with the depth of point rainfall. However, the area reduction factor showing the ratio of area rainfall to the maximum point rainfall varies from.5 to.8 for the area rainfall amount. Further, the area reduction factor does not always increase with the enlargement of the point rainfall. On the other hand, the design area reduction factors examined in several hydropower projects varies from.4 to.5. In due consideration above, the design area reduction factor is conservatively determined to be.5. 2) Probable Point Rainfall Out of the available rainfall records around the Masang River basin, the annual maximum 1-day rainfall records are available at the Payakumbuh rainfall gauging station as presented in Table 25. As seen in this table, the rainfall records at the Payakumbuh station have recording periods between 1951 and 1993 with some interruptions in recording. The probable point rainfalls at the station with several return periods are estimated through frequency analysis using the Gumbel and Log Normal distributions as summarized below. The estimated frequency curves of probable daily rainfall at these stations are also presented in Figure 33. Return Period Probable Point Rainfall (mm) (years) Gumbel LN Average The probable point rainfall is estimated as the average of the probable rainfalls by the Gumbel and Log Normal distributions, because the estimated frequency curves by the Gumbel and Log Normal distributions have similar shapes. JICA Project for the Master Plan Study of August, 211

23 3) Probable Maximum Precipitation (PMP) Generally three (3) approaches are used for estimating the probable maximum precipitation (PMP) as follows. Meteorological (theoretical) approach in consideration of the upper physical limit of moisture source Statistical approach which is empirically developed by Dr. Hershfield from the rainfall records in the United States of America Historical approach by examining the historical maximum one over occurred in the area of interest The available basic climatological data such as dew point, humidity, wind velocity in Masang-2 catchment area for the first meteorological approach are insufficient for the time being. Further, no historical rain storm records are also so far available. Therefore, PMP is estimated by the simple statistical Hershfield method using a series of the annual maximum daily rainfall records. This method is widely applied in the basin where rainfall records are available but other basic climatological records are hardly obtainable. The Hershfield s equation is expressed as follows. X = X + K S m n m n where, X m : Extreme value of 24-hour rainfall (PMP) (mm) X n : Adjusted mean annual maximum rainfall (mm) K m : Statistical coefficient S : Adjusted standard deviation of a series of annual maximum rainfall n As seen in the above equation, PMP in question is assumed to be given as the adjusted mean annual maximum rainfall in question plus the K m times the standard deviation of a series of annual maximum rainfall in question. The PMP is estimated by applying a series of annual maximum rainfall in the Masang river basin. The calculation process is as follows. Computation of Statistical Parameters The mean annual maximum rainfall (X n ) and its standard deviation (S n ) are calculated to be 96.1 mm and 47.1 mm, respectively. Concurrently with the above, X n-m and S n-m are estimated at 91.6 mm and 38.2 mm, which are computed after excluding the maximum rainfall in the series of rainfall data. These statistical JICA Project for the Master Plan Study of August, 211

24 parameters are used for several adjustment necessary computing X n and S n. Adjustment of X n and S n for Maximum Observed Event The adjustment factors of X n (f x1 ) and S n (f s1 ) for the maximum observed rainfall shall be obtained from the Hershfield s adjustment curves as shown in Figure 34 and Figure 35. Applying the values of X n, X n-m, S n and S n-m, adjustment factors are obtained 97 % for f x1 and 89 % for f s1, respectively. Adjustment of X n and S n for Sample Size The adjustment factors of X n (f x2 ) and S n (f s2 ) for the length of record shall be obtained from the adjustment curves as presented in Figure 36. The obtained factors of f x2 and f s2 are 1.5 % and 11.6 %, respectively. Statistical Coefficient K m The statistical coefficient K m shall be obtained from the empirical K m curves as presented in Figure 37. Applying the mean annual maximum rainfall at the Payakumbuh station (X n ) is 96.1 mm, the Km value is obtained to be Adjustment for Fixed Observational Time Intervals Rainfall observation has been carried out on the daily basis at the Payakumbuh station. Since the recorded daily rainfall is computed based on the single fixed observation time interval (say 8 a.m to 8 p.m), the PMP value yielded by the statistical procedure should be increased multiplying by the adjustment factor (f o ). The adjustment factor curve is presented by Dr. Hersfield as shown in Figure 38. Applying that the number of observation units is equal to 1, the f o value is obtained to be 113 %. Computation of PMP at the Payakumbuh Station The adjustment mean annual maximum rainfall (X n ) is finally given as follows. X X n = f X 1 f X 2 n In addition, the adjusted standard deviation of a series of annual maximum rainfall (S n ) is given as follows. S S n = f S1 fs 2 n The unadjusted point PMP (X m ) is computed as follows. JICA Project for the Master Plan Study of August, 211

25 X = X + K S m n m n Finally, the point PMP is adjusted using the adjustment factor f o as follows. PMP = f O X m The computation process of the point PMP is summarized in Table 26. As seen, the point PMP at the Payakumbuh station is estimated to be 852 mm. 4) Basin Mean Rainfall Applying the design area reduction factor of.5, the probable basin mean 1-day rainfalls with various return periods as well as PMP at the Masang-2 intake weir site are estimated as follows. Return Period (years) Probable Rainfall (mm) PMP (3) Hydrograph Analysis 1) Unit hydrograph Since no flood hydrographs are available for the present flood analysis, the unit hydrograph is developed by means of the SCS (Soil Conservation Service) synthetic hydrograph method. The SCS method was developed by analyzing a large number of basins with varying geographic locations. Unit hydrographs were evaluated for a large number of actual watersheds and then made dimensionless by dividing all discharge ordinates by the peak discharge and the time ordinates by the time to peak. An average of these dimensionless unit hydrographs was computed. a) SCS Unit Hydrograph The SCS unit hydrograph is derived from the flood concentration time and unit basin rainfall. The unit hydrograph is constructed for a unit rainfall of 1 mm. The peak discharge of the unit hydrograph is calculated as follows. JICA Project for the Master Plan Study of August, 211

26 q =.28AQ / p t p where, q p : Peak discharge (m 3 /sec) A : Basin area (km 2 ) Q : Total volume of the unit hydrograph (=1mm) t p : Time to peak (hours) SCS has determined that the time to peak ( t p ) and rainfall duration ( D ) are related to time of concentration ( t c ) as follows. t = p 2 tc /3 D =. 133t c b) Flood Concentration Time The flood concentration time is defined as the time of travel from the most remote point in the catchment to the forecast point. The flood concentration time can be estimated by the formula of Kirpich as follows. t c = 3.97 L S where, t c : Flood concentration time (min) L : Maximum length of travel of water (km) S : Average slope (=H/L, where H is the difference in elevation between the remotest point in the basin and the outlet) c) SCS Unit Hydrograph Calculation With a maximum length of travel ( L ) of 49km, the concentration time ( t c ) was found to be about 6.2 hours. With a catchment area ( A ) of 443 km 2, the peak flow ( q ) is found to be 22.3 m 3 /sec/mm. The average slope of the Masang River is illustrated in Figure 39. The SCS unit hydrograph for the Masang River basin is shown in Figure 4. A 443 km 2 Q 1 mm L km t c 6.2 hours q p 22.3 m 3 /s/mm 4.1 hours t p p JICA Project for the Master Plan Study of August, 211

27 2) Probable Flood Hydrograph at Masang-2 Intake Weir Site The probable flood hydrographs including PMF at the Masang-2 intake weir site are derived by convolution of the probable basin mean rainfall, PMP with the design rainfall hyetograph and the unit hydrograph. The base flow is determined to be 14 (m 3 /s) from the average rainy-season discharge records at the Sipisang AWLR station, and the rainfall loss is assumed to be 47 %. The daily hydrograph is shown in Figure 41, and the rainfall loss is presented in Table 28. The computed probable flood hydrographs as well as PMF are presented in Table 29 and shown in Figure 42. The probable design flood discharges with various return periods together with PMF are collected from various hydropower projects in Sumatra as presented in Table 3. 3) Creager s Coefficient for Probable Floods at Masang-2 Intake Weir Site Creager s coefficient for probable flood is computed by the following equations. Q = ( ) C (.3861 A) p a a =.894(.3861 A).48 where, Q p : Peak discharge of probable flood (m 3 /sec) C : Creager s coefficient A : Catchment area (km 2 ) The Creager s coefficients corresponding to the various return periods and PMF for the Masang-2 HEPP are enumerated in the table below. T Q C (year) (m3/s) PMF Figure 43 and Figure 44 shows the relationship between probable flood peak discharges with return periods of 2, 2, 1, 2 years as well as PMF and catchment area for the Masang-2 JICA Project for the Master Plan Study of August, 211

28 HEPP and other water resources development projects in the whole Sumatra. The Creager s curves are illustrated using the Creager s coefficients of the Masang-2 intake weir site calculated in above. The probable floods at the Masang-2 HEPP are well plotted in reasonable range of design floods in Sumatra. 4) Probable Floods at the Masang-2 Regulating Pond Site The time of concentration ( t c ) at the Masang-2 Regulating Pond is calculated as.17 hour with the same method as the Masang-2 intake weir site. Probable floods at the Masang-2 Regulating Pond are estimated with the Creager s coefficients of the Masang-2 intake weir site, because short time interval rainfall records like 1-minutes do not exist in Masang River basin. The catchment area of the Masang-2 intake weir site is illustrated in Figure 46. A 1 km 2 L t c 1.3 km.17 hours The results of flood analysis are estimated as follows. Intake Pond T Q C Q (year) (m3/s) (m3/s) PMF ) Probable Floods at the Masang-2 Power House Site The Alahanpanjang River and the Masang River join together at the upstream of the Masang-2 Power House site. At the power house site, probable floods seem to be controlled by floods from the Masang River, because the catchment area of the Alahanpanjang River basin is smaller than the Masang River basin. So, Probable floods at the Masang-2 power house site are estimated with the Creager s coefficients of the Masang-2 intake weir site as same as the regulating pond. The catchment area of the power house site is 919.5km 2, illustrated in Figure 47. The results of flood analysis are estimated as follows. JICA Project for the Master Plan Study of August, 211

29 Intake PH T Q C Q (year) (m3/s) (m3/s) PMF (4) Water Level Observation and Discharge Measurement As mentioned in the chapter of lowflow analysis, the field investigation of 3 month water level observation and 3 times discharge measurement was carried out from 21 October 6 th to 211 January 7 th by the sub-contractor. Consequently, the maximum water level is 2.1m and the maximum runoff is m 3 /s calculated with H-Q rating curve in extrapolation. The Equation of H-Q rating curve is given below. Q = ( H +.6) 2 where, Q : Runoff (m 3 /sec) H : Water level (m) SEDIMENT ANALYSIS (1) General Sedimentation analysis is preliminarily carried out to estimate the denudation rate in the Masang River basin. The sedimentation load is herein predicted based on the estimated runoff and the sediment discharge rating curve at the intake weir site. The rating curve is established based on the in-situ sampling records obtained through the field investigation conducted in the course of the study. The field investigation was carried out at the Masang-2 intake weir site and Sipisang AWLR station. The sediment transport in the Masang River is judged to be higher than other rivers in the Sumatra. The denudation rate showing the expected average annual erosion rate in a river basin is generally influenced by the topography (soil condition, river gradient), deforestation of the land in the basin, rainfall intensity, etc. In addition, the design denudation rates adopted in other water resources or hydropower JICA Project for the Master Plan Study of August, 211

30 development projects in Sumatra are collected for comparison purposes. (2) Suspended Load Sampling A total of thirty (3) suspended load samplings were carried out at the intake weir site where discharge measurements were taken. The samples were taken to a laboratory for further analysis. The sieve analysis results of samples are shown in Figure 48. (3) Suspended Load Rating Curve The laboratory analysis results of the samples show the total suspended sediment concentration which is the combination of both dissolved and undissolved sediment. The total suspended load is found from the following formula. Q =. 864 C S Q W where, Q S : Suspended load (ton/day) C : Total suspended sediment concentration (mg/l) Q : Flow discharge (m 3 /s) W The suspended load calculations using the above formula are presented in Table 31. Several results are considered unreliable because they show very low concentration or very high concentration. Therefore these unreliable results will not be used in the determination of the suspended load rating curve. The values of Qs are plotted against their respective Qw values to determine the suspended load rating curve. On the basis of the estimated sediment discharge at the intake weir site, the suspended load rating curve is established as shown in Figure 49. The rating curve equation is given below. S QW Q = If the flow discharge Qw is known, the suspended load sediment Qs can be estimated. (4) Total Sediment Load The annual suspended load sediment yield is simulated by applying the above rating curve to the simulated daily runoff at the intake weir site. The catchment area of the Masang-2 intake weir site is 443km 2. Substituting runoff data, the average annual suspended load sediment at the intake weir site is estimated at 369,749 ton. The density of sediment in appearance can be calculated by the following equation. γ = ( 1 V ) γ where, γ : Density of sediment (ton/m 3 ) JICA Project for the Master Plan Study of August, 211

31 V : Void ratio of sediment γ : Unit weight of sediment (=2.65ton/m 3 ) Assuming a void ratio of 6 % in sedimentation, the density of sediment is found to be 1.6 ton/m 3. Hence, the annual suspended load sediment is estimated at 348,82 m 3. The sediment load transport into an intake weir generally consists of suspended load and bed load. It is generally accepted that it might be difficult to accurately measure the bed load in a natural river. Usually, the rate of bed load transport is empirically estimated at 1 to 3 % of the total suspended load. The rate of bed load transport is estimated as 1% of the total suspended load, because 1% is usually applied in Indonesia. Consequently, the mean annual sediment inflow volume into the Masang-2 intake weir is estimated to be 383,72 m 3, which is equivalent to a denudation rate of.87 mm per year. For comparison purpose, design denudation rates of various schemes around the project site are presented in the following table. Project Name Project Stage Province Catchment Area Denudation Rate (km2) (mm/year) Masang-3 Pre-F/S W. Sumatra Bt. Tonggar W. Sumatra Bt. Bayang-1 Pre-F/S W. Sumatra 84.7 Bt. Bayang-2 Pre-F/S W. Sumatra 36.7 Kotapanjang D/D Riau 3,337.5 Kampar River Basin F/S Jambi -.5 Upper Indragiri River Basin Jambi -.59 Middle Indragiri River Basin Jambi -.53 Merangin-2 D/D Jambi 1,39.34 Merangin-5 Pre-F/S Jambi 2,597.7 Lake Kerinci Jambi 1,53.72 Source: Masang-3 HEPP, As seen in the above table, the design denudation rates vary from.34 to.72 mm/year. The assumed denudation rate of.87 mm/year at the Masang-2 intake weir site might not be in the appropriate range. Referring to the geology report in this study, there is place of gravel pit in the upstream of Masang River, and gravel extraction is seems to be carried out frequently. The samples of suspended load might be influenced by the gravel extraction. The gravel extraction might not be continuously carried out, so the design denudation rate of the Masang-2 intake weir should be estimated without influence of the gravel extraction in upstream. Nevertheless, it is difficult to estimate the volume of sediment yield from the gravel pit. The grain size distributions of the samples are consists of mainly fine size grain smaller than.1mm, of which falling velocity is slow. It is estimated that the fine size grain has small influence to the sedimentation in the intake weir. JICA Project for the Master Plan Study of 16-3 August, 211

32 Consequently, the design denudation rate of the Masang-2 intake weir is estimated as.5mm/year which is the middle of design denudation rates in other projects. The design annual sediment inflow volume into the Masang-2 intake weir is estimated to be 221,5m 3 /year WATER QUALITY ANALYSIS Water quality is important because it is linked to the availability of water for various uses. Specifically, for the Masang-2 HEPP it is important for the well being of hydraulic machinery, other equipment and hydraulic structures used in the project. The laboratory test for water quality was carried out through the field investigation under the current study to identify the content of various chemical elements contained in the water in the Masang River. Water sampling is carried out three (3) times in total at the Masang-2 intake weir site. The samples were taken to a laboratory for further analysis. The laboratory test results are presented in Table 32. The table shows that the ph of the water in the Masang River is around 8. It is therefore judged that the water in the Masang River will have no adverse effect on turbine and metal for hydropower use, because adverse effect is expected to occur under the ph value smaller than 4.5. JICA Project for the Master Plan Study of August, 211

33 Table 1 Monthly Mean Air Temperature Station Name: Tabing-Padang Elevation: 2.m Unit: Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Min Max Ave Source: ( ) Masang-3 HEPP Report, 1999 (199-22) BMKG JICA Project for the Master Plan Study of T-1 August, 211

34 Table 2 Monthly Mean Relative Humidity Station Name: Tabing-Padang Elevation: 2.m Unit: % Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Min Max Ave Source: ( ) Masang-3 HEPP Report, 1999 (199-22) BMKG JICA Project for the Master Plan Study of T-2 August, 211

35 Table 3 Monthly Mean Sunshine Duration Station Name: Tabing-Padang Elevation: 2.m Unit: % Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Min Max Ave Source: ( ) Masang-3 HEPP Report, 1999 (199-22) BMKG JICA Project for the Master Plan Study of T-3 August, 211

36 Table 4 Monthly Mean Wind Velocity Station Name: Tabing-Padang Elevation: 2.m Unit: m/sec Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Min Max Ave Source: ( ) Masang-3 HEPP Report, 1999 (199-22) BMKG JICA Project for the Master Plan Study of T-4 August, 211

37 Table 5 Monthly Mean Pan Evaporation Station Name: Lubuk Sukaping Unit: mm/day Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Min Max Ave Source: Masang-3 HEPP Report, 1999 Station Name: Tanjung Pati Unit: mm/day Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Min Max Ave Source: Masang-3 HEPP Report, 1999 JICA Project for the Master Plan Study of T-5 August, 211

38 Table 6 Monthly Rainfall Records (1/13) Station Name: Maninjau Station ID: 52B Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , , , , , , , , Min Max ,88 65 Ave ,199 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-6 August, 211

39 Table 7 Monthly Rainfall Records (2/13) Station Name: Limau Purut Station ID: 52C Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , Min Max Ave ,491 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-7 August, 211

40 Table 8 Monthly Rainfall Records (3/13) Station Name: Padang Panjang Station ID: 53 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , , , , , , , , Min Max , , Ave ,76 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-8 August, 211

41 Table 9 Monthly Rainfall Records (4/13) Station Name: Bukit Tinggi Station ID: 54 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , Min Max Ave ,21 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-9 August, 211

42 Table 1 Monthly Rainfall Records (5/13) Station Name: Baso Station ID: 54A Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , Min Max Ave ,12 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-1 August, 211

43 Table 11 Monthly Rainfall Records (6/13) Station Name: Padang Mangatas Station ID: 54C Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , Min Max Ave ,45 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-11 August, 211

44 Table 12 Monthly Rainfall Records (7/13) Station Name: Payakumbuh Station ID: 56 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , Min Max , Ave ,181 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-12 August, 211

45 Table 13 Monthly Rainfall Records (8/13) Station Name: Koto Tinggi Station ID: 56A Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , , , , , , , , , , , Min Max Ave ,638 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-13 August, 211

46 Table 14 Monthly Rainfall Records (9/13) Station Name: Suliki Station ID: 56B Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , , , , , , , , ,486 1, ,441 6, , , , Min Max ,486 1, , ,441 Ave ,44 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-14 August, 211

47 Table 15 Monthly Rainfall Records (1/13) Station Name: Kota Baharu Station ID: 57 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , Min Max Ave ,828 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-15 August, 211

48 Table 16 Monthly Rainfall Records (11/13) Station Name: Bonjol Station ID: 58C Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , Min Max , , Ave ,613 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-16 August, 211

49 Table 17 Monthly Rainfall Records (12/13) Station Name: Jambak Station ID: 58F Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , , , , , , , , Min Max Ave ,797 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-17 August, 211

50 Table 18 Monthly Rainfall Records (13/13) Station Name: Lubuk Sikaping Station ID: 59 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , , , , Min Max Ave ,76 Source: HPPS2 Report, Masang-3 HEPP Report, BMKG JICA Project for the Master Plan Study of T-18 August, 211

51 Table 19 Selected Hourly Rainfall Records Unit:mm Total Hour Station Name Date Rainfall Gunung 1982/12/ Melintang 1983/1/ /3/ /4/ /9/ /12/ /3/ /4/ /4/ /1/ /11/ /11/ /11/ /1/ /1/ /1/ /2/ /3/ /3/ /5/ /5/ /9/ /1/ /3/ Maninjau 1986/5/ /7/ /7/ /8/ /1/ /8/ /1/ Sungai Talang 1991/9/ Barat 1991/12/ /3/ Solok Bio-Bio 1991/1/ /3/ Muara Paiti 1984/1/ /11/ /11/ /11/ /12/ /2/ /3/ /8/ /1/ /12/ /1/ /2/ /9/ /9/ /1/ /1/ /1/ /6/ /11/ /11/ Patir 1989/4/ Puar Datar 1992/12/ Halaban Dua 1991/8/ /11/ /12/ /12/ /4/ Source:Masang-3 HEPP, JICA Project for the Master Plan Study of T-19 August, 211

52 Table 2 Monthly Mean Runoff Records Station Name: Sipisang Station ID: Unit: m3/s Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Min Max Ave Source: Pusair. Masang-3 HEPP, JICA Project for the Master Plan Study of T-2 August, 211

53 Table 21 Regression Analysis of Monthly Rainfall Records Number of Data 52B 52C A 54C 56 56A 56B 57 58C 58F 59 Maninjau 52B Limau Purut 52C Padang Panjang Bukit Tinggi Baso 54A Padang Mangatas 54C Payakumbuh Koto Tinggi 56A Suliki 56B Kota Baharu Bonjol 58C Jambak 58F Lubuk Sikaping Correlation Ratio 52B 52C A 54C 56 56A 56B 57 58C 58F 59 Maninjau 52B Limau Purut 52C Padang Panjang Bukit Tinggi Baso 54A Padang Mangatas 54C Payakumbuh Koto Tinggi 56A Suliki 56B Kota Baharu Bonjol 58C Jambak 58F Lubuk Sikaping Slope of Formula (Y=aX) X 52B 52C A 54C 56 56A 56B 57 58C 58F 59 Maninjau 52B Limau Purut 52C Padang Panjang Bukit Tinggi Baso 54A Padang Mangatas 54C Payakumbuh Koto Tinggi 56A Suliki 56B Kota Baharu Bonjol 58C Jambak 58F Lubuk Sikaping JICA Project for the Master Plan Study of T-21 August, 211

54 Table 22 Estimated Monthly Basin Mean Rainfall at Sipisang AWLR Station Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual , , , , , , , , , , , , , , , , , , , , ,27 Min Max Ave ,57 JICA Project for the Master Plan Study of T-22 August, 211

55 Table 23 Annual Rainfall Loss of Various River Basins in Sumatra No. Station River Gauge ID Catchment Basin Annual Annual Annual Runoff Observation Name Basin Area Mean Mean Runoff Rainfall Coeff. Period Rainfall Runoff Depth Loss (km 2 ) (mm) (m 3 /sec) (mm) (mm) 1 Lhok Nibong Kr. Jambu Aye ,583 2, ,29 1, Stabat S. Wampu ,87 3, ,685 1, Lb. Sipelanduk Bt. Pane , ,82 1, Lb. Bendahara S. Rokan ,325 2, ,342 1, Tj. Ampalu Bt. Kuantan ,215 2, ,15 1, Sungai Dareh Bt. Hari ,452 3, ,197 1, Muara Inum Bt. Hari ,455 3, ,332 1, Martapura A. Musi ,26 2, ,666 1, Banjarmasin W. Tl. Bawang , ,921 1, Kunyir W. Sekampung , ,663 1, Kp. Darang Kr. Aceh ,81 2, , Tui Kareng Kr. Teunom ,43 3, ,413 1, Hp. Baru Bt. Toru ,773 2, ,466 1, Air Batu Bt. Indrapura , , Air Gadang Bt. Pasaman ,339 3, , Despetah A. Musi , , Source : Sectoral Report Vol. 2 : Hydrology, Hydro Inventory Study, July 1997 JICA Project for the Master Plan Study of T-23 August, 211

56 Table 24 Area Reduction Factor for Masang River Basin Maninjau Payakumbuh No Date Point Rainfall (mm) Area Average Reduction Maninjau Payakumbuh Factor /9/ /5/ /9/ /1/ /9/ /11/ /4/ /11/ /6/ /1/ /12/ /4/ /9/ /5/ /5/ /1/ /9/ /1/ /9/ /7/ /2/ /7/ /8/ /4/ /5/ Average.58 JICA Project for the Master Plan Study of T-24 August, 211

57 Table 25 Annual Maximum 1-Day Rainfall at Payakumbuh Station Unit: mm Year Rainfall Source: BMKG. Masang-3 HEPP, JICA Project for the Master Plan Study of T-25 August, 211

58 Table 26 Calculation of Probable Maximum Precipitation (PMP) Annual Maximun 1-Day Precipitation at Payakumbuh Station Unit: mm Year Rainfall Max = 27 mm (1966) n = X n = 96.1 mm S n = 47.1 mm X n-m = 91.6 mm S n-m = 38.2 mm X n-m / X n = S n-m / S n = Adjustment for Maximum Observed Event f X1 = 97% f S1 = 89% Adjustment for Sample Size f X2 = 1.5% f S2 = 11.6% Statistical Coefficient K m = Adjustment for Fixed Observational Time Intervals f = 113% Computation of PMP X n = f X1 * f X2 * X n = 93.6 mm S n = f S1 * f S2 * S n = 42.6 mm X m = X n + K m * S n = 754. mm PMP = f * X m = 852. mm JICA Project for the Master Plan Study of T-26 August, 211

59 Table 27 Ratios for SCS Unit Hydrograph t/t p q/q p JICA Project for the Master Plan Study of T-27 August, 211

60 Table 28 Average Rainfall Loss at Sipisang AWLR Station Monthly Runoff Sipisang Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Adjusted Monthly Basin Mean Rainfall Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Number of Days Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Runoff Depth Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall Loss in Rainy Season Average.473 JICA Project for the Master Plan Study of T-28 August, 211

61 Table 29 Probable Flood Hydrographs at Masang-2 Intake Weir Site Catchment Area = 443 km2 Unit:m3/s Time Return Period (year) (hour) PMF Peak JICA Project for the Master Plan Study of T-29 August, 211

62 Table 3 Probable Floods under Various Schemes in Sumatra Catchment Probable Peak Discharge (m3/sec) No Scheme River Province Area Return Period (year) (km2) , 1, PMF 1 Tampur-1 Kr. Tampur D.I. Aceh 2,25 2,87 3,59 7,47 2 Teunom-1 Kr. Teunom D.I. Aceh 9 2,3 3,12 8,39 3 Aceh-2 Kr. Aceh D.I. Aceh 323 1,3 1,47 3,51 4 Lawe Alas-4 Lawe Alas D.I. Aceh 5,75 2,5 4,25 12,5 5 Peusangan-4 Kr. Peusangan D.I. Aceh 945 1,6 6 Lake Laut Tawar Kr. Peusangan D.I. Aceh ,67 7 Residual Basin-1 Kr. Peusangan D.I. Aceh ,2 8 Jambu Aye Kr. Jambu Aye D.I. Aceh 3,89 1,939 2,331 3,8 4,85 9 Rubek Kr. Jambu Aye D.I. Aceh Residual Basin-2 Kr. Peusangan D.I. Aceh Lalang S. Belawan N. Sumatera Tembakau S. Percut N. Sumatera Lausimeme S. Percut N. Sumatera Helvetia S. Deli N. Sumatera Namobatang S. Deli N. Sumatera Baru S. Serdang N. Sumatera Pulau Tagor S. Ular N. Sumatera 1, ,7 18 Karai S. Ular N. Sumatera Brohol S. Padang N. Sumatera Rampah S. Belutu N. Sumatera Renun A. Renun N. Sumatera ,9 22 Wampu S. Wampu N. Sumatera 1,57 2,97 23 Limang S. Wampu N. Sumatera Sipan Sihaporas Sipan Sihaporas N. Sumatera ,8 25 Batang Bayang-1 Bt. Bayang W. Sumatera Batang Bayang-2 Bt. Bayang W. Sumatera Muko-Muko Bt. Antokan W. Sumatera Masang-3 Bt. Masang W. Sumatera 993 1,136 2,24 2,878 3,168 3,851 4,854 1, Merangin-5 Bt. Merangin Jambi 2,597 1,97 2,46 5,3 3 Lake Kerinci Siulak Jambi ,538 2,177 2,464 3,12 4,92 13, Batang Hari Bt. Hari Jambi 4,452 1,937 4,192 5,63 6,25 7,61 32 Batang Hari (Alt.) Bt. Hari Jambi 3,825 1,664 3,62 4,814 5,331 6, Kiri-1 Bt. Kampar Riau 1,187 2,537 7, Kiri-2 Bt. Kampar Riau 552 1, Kapoernan Bt. Kampar Riau 699 2, Kotapanjang Bt. Kampar Riau 3,337 1,183 1,624 8, 11,4 37 Upper Sinamar Bt. Indragiri Riau 3,18 3,18 8, Sukam Bt. Indragiri Riau 36 1, Lower Kuantan Bt. Indragiri Riau 7,453 1,47 4 Ombilin Bt. Ombilin Riau 1, Musi (Intake Dam) A. Musi S. Sumatera ,1 1,31 42 Musi (Regulation Dam) A. Musi S. Sumatera Martapura Way Komering S. Sumatera 4,26 1,3 1,9 2,2 2,3 2,7 6,3 44 Lematang-4 A. Lematang S. Sumatera 1,321 1,87 2,43 5,5 45 Mine Mouth Steam Plant A. Lematang S. Sumatera 3,667 6, Ketaun-1 A. Ketaun Bengkulu ,7 7,14 Masang-2 Bt. Masang W. Sumatera ,198 1,341 4,344 Source: Hydro Inventory Study, Sectral Report Vol.2 Hydrology, July Masang-3 HEPP, JICA Project for the Master Plan Study of T-3 August, 211

63 Table 31 Calculations of Suspended Load in Masang River No Sampling Date Water Level Qw C Qs Remarks Site (m) (m3/s) (mg/l) (ton/day) 1 Intake Weir 21/1/ , Intake Weir 21/1/ , , Intake Weir 21/1/ , , U 4 Intake Weir 21/1/ Intake Weir 21/11/ , Intake Weir 21/11/ , , Intake Weir 21/11/ , , Intake Weir 21/12/ , , Sipisang AWLR Station 21/12/ D 1 Sipisang AWLR Station 21/12/ D Legend U: The concentration value is not reliable and not considered in the determination of the suspended load rating curve. D: Sampling was carried out at the Sipisang AWLR Station and not considered in the determination of the suspended load rating curve. JICA Project for the Master Plan Study of T-31 August, 211

64 Table 32 Water Quality Analysis of Masang River No Water Quality Parameter Unit Sample-1 Sample-2 Sample-3 Date 21/1/25 21/11/25 21/12/25 Weather Clear Cloud Cloud 1 ph Temperature Total Hardness mg/l Temporary Hardness mg/l Suspended Matter mg/lit Total Solid mg/lit Ignition Residue mg/lit Permanganate Value as O2 mg/lit Carbonates as CaCO3 mg/lit Bicarbonates as CaCO3 mg/lit Calcium (Ca) mg/lit Magnesium (Mg) mg/lit Sodium (Na) mg/lit Potassium (K) mg/lit Iron (Fe) mg/lit Manganese (Mn) mg/lit < Copper (Cu) mg/lit < Turbidity NTU Color Pt-Co-Unit 2 1 kol 1 kol 2 Electric Conductivity µ/cm Aluminum (Al) mg/lit Silica (SiO2) mg/lit Lead (Pb) mg/lit Arsenic (As) mg/lit Ammonium (NH4) mg/lit.784 <.2 <.2 26 Albuminoid mg/lit <.1 <.1 <.1 27 Nitrites (NO2) mg/lit Nitrates (NO3) mg/lit Sulfities (SO3) mg/lit <.2 3 Sulfates (SO4) mg/lit Chlorides (Cl) mg/lit Phosphates (PO4) mg/lit.49 <.2 <.2 33 Oxygen (O2) mg/lit Carbon Dioxide (CO2) mg/lit P-value as CaCO3 mg/lit.52 <.2 <.2 36 M-Value as CaCO3 mg/lit JICA Project for the Master Plan Study of T-32 August, 211

65 Figure 1 Location Map of Meteo-Hydrological Stations JICA Project for the Master Plan Study of F-1 August, 21

66 Daily Rainfall Records BMG HPPS2 No. Station Name ID ID 1 Maninjau 52B Year Remarks 2 Limau Purut 52C Padang Panjang Bukit Tinggi Baso 54A Padang Mangatas 54C Payakumbuh Koto Tinggi 56A Suliki 56B Kota Baharu Bonjol 58C Jambak 58F Lubuk Sikaping Source: BMKG Monthly Rainfall Records BMG HPPS2 No. Station Name ID ID 1 Maninjau 52B Year Remarks 2 Limau Purut 52C Padang Panjang Bukit Tinggi Baso 54A Padang Mangatas 54C Payakumbuh Koto Tinggi 56A Suliki 56B Kota Baharu Bonjol 58C Jambak 58F Lubuk Sikaping Source: HPPS2 Report, Masang-3 HEPP Report, BMKG Figure 2 Availability of Climatic Records (1/2) JICA Project for the Master Plan Study of F-2 August, 21

67 Daily Runoff Records DPMA HPPS2 No. Station Name ID ID Remarks 1 Bt. Masang Sipisang years Source: Pusair Bandung Year Daily Water Level Records DPMA HPPS2 No. Station Name ID ID 1 Bt. Masang Sipisang Source: BPSDA Bukit Tinggi Year Remarks Monthly Runoff Records DPMA HPPS2 No. Station Name ID ID 1 Bt. Masang Sipisang Source: HPPS2 Report, Masang-3 HEPP Report, Pusair Bandung. Year Remarks Air Temperature BMG HPPS2 No. Station Name ID ID 1 Tabing-Padang Source: BMKG Relative Humidity BMG HPPS2 No. Station Name ID ID 1 Tabing-Padang Source: BMKG Sunshine Duration BMG HPPS2 No. Station Name ID ID 1 Tabing-Padang Source: BMKG Wind Velocity BMG HPPS2 No. Station Name ID ID 1 Tabing-Padang Source: BMKG Year Year Year Year Remarks Remarks Remarks Remarks Pan Evapolation Management No. Station Name Body 1 Lubuk Sikaping BMG 2 Tanjung Pati P3SA Source: Masang-3 HEPP Report, 1999 : Complite Data : Incomplite Data Year Remarks Figure 3 Availability of Climatic Records (2/2) JICA Project for the Master Plan Study of F-3 August, 21

68 B. A. Alahanpanjang Power House Site B. Masang Sipisang AWLR station B. Masang S. Guntung Masang-2 Basin 443km 2 Masang-2 Intake Weir Site B. Sianok Figure 4 Catchment Area of Masang-2 Intake Weir based on 1:5, map JICA Project for the Master Plan Study of F-4 August, 211

69 Final Report (Supporting_PreF/S) Monthly Mean Air Temperature St. Tabing-Padang Monthly Mean Relative Humidity St. Tabing-Padang Temperature ( ) Humidity ( % ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month 79. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Monthly Mean Sunshine Duration St. Tabing-Padang Monthly Mean Wind Velocity St. Tabing-Padang Duration ( % ) Velocity ( m/s ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Monthly Mean Pan Evaporation St. Lubuk Sukaping Monthly Mean Pan Evaporation St. Tanjung Pati Evaporation ( mm/day ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Evaporation ( mm/day ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Figure 5 Variations of Principal Climatic Data JICA Project for the Master Plan Study of F-5 August, 211

70 Final Report (Supporting_PreF/S) Figure 6 Location Map of Hourly Rainfall Stations JICA Project for the Master Plan Study of F-6 August, 211

71 Final Report (Supporting_PreF/S) Accumulated Hourly Rainfall (mm) Station Name: Gunung Melintang Time (hour) Accumulated Hourly Rainfall (mm) Station Name: Maura Paiti Time (hour) Accumulated Hourly Rainfall (mm) Station Name: Maninjau, Sungai Talang Barat, Solok Bio-Bio, Patir, Puar Datar, Halaban Dua Time (hour) Figure 7 Accumulated Hourly Rainfall Curves JICA Project for the Master Plan Study of F-7 August, 211

72 Final Report (Supporting_PreF/S) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1975 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1976 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1977 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1978 Figure 8 Daily Runoff Hydrograph (1/7) JICA Project for the Master Plan Study of F-8 August, 211

73 Final Report (Supporting_PreF/S) Discharge (m3/s) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1981 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1982 Figure 9 Daily Runoff Hydrograph (2/7) JICA Project for the Master Plan Study of F-9 August, 211

74 Final Report (Supporting_PreF/S) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1983 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1984 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1985 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1986 Figure 1 Daily Runoff Hydrograph (3/7) JICA Project for the Master Plan Study of F-1 August, 211

75 Final Report (Supporting_PreF/S) Discharge (m3/s) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1991 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 11 Daily Runoff Hydrograph (4/7) 1992 JICA Project for the Master Plan Study of F-11 August, 211

76 Final Report (Supporting_PreF/S) Discharge (m3/s) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1996 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1997 Figure 12 Daily Runoff Hydrograph (5/7) JICA Project for the Master Plan Study of F-12 August, 211

77 Final Report (Supporting_PreF/S) Discharge (m3/s) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Discharge (m3/s) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 2 21 Figure 13 Daily Runoff Hydrograph (6/7) JICA Project for the Master Plan Study of F-13 August, 211

78 Final Report (Supporting_PreF/S) Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 25 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 26 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 27 Discharge (m3/s) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 28 Figure 14 Daily Runoff Hydrograph (7/7) JICA Project for the Master Plan Study of F-14 August, 211

79 Final Report (Supporting_PreF/S) Water Level (m) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Water Level (m) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Water Level (m) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Water Level (m) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 15 Observed Daily Water Level Records (1/2) JICA Project for the Master Plan Study of F-15 August, 211

80 Final Report (Supporting_PreF/S) Water Level (m) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Water Level (m) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 16 Observed Daily Water Level Records (2/2) JICA Project for the Master Plan Study of F-16 August, 211

81 Final Report (Supporting_PreF/S) Accumulation of annual rainfall at Maninjau station 8, 6, 4, 2, - y =.6675x y = 1.472x , 4, 6, 8, Accumulation of average annual rainfall at surrounding stations Accumulation of annual rainfall at Koto Tinggi station 8, 6, 4, 2, , 4, 6, 8, Accumulation of average annual rainfall at surrounding stations Accumulation of annual rainfall at Suliki station 8, 6, 4, 2, - y = x y =.656x , 4, 6, 8, Accumulation of average annual rainfall at surrounding stations Accumulation of annual rainfall at Jambak station 8, 6, 4, 2, , 4, 6, 8, Accumulation of average annual rainfall at surrounding stations Figure 17 Double Mass Curves of Rainfall Records JICA Project for the Master Plan Study of F-17 August, 211

82 Final Report (Supporting_PreF/S) Figure 18 Thiessen Polygon JICA Project for the Master Plan Study of F-18 August, 211

83 Final Report (Supporting_PreF/S) 2, Annual Runoff Depth (mm) 2, 1,5 1, 5 mm 7mm mm , 1,5 2, 2,5 3, 3,5 4, Annual Basin Mean Rainfall (mm) Figure 19 Relationship between Annual Basin Mean Rainfall and Annual Runoff Depth at Sipisang AWLR Station 4,5 4, mm Annual Runoff Depth (mm) 3,5 3, 2,5 2, 1,5 7 mm 1,5 mm 1, 5 5 1, 1,5 2, 2,5 3, 3,5 4, 4,5 Annual Basin Mean Rainfall (mm) Figure 2 Relationship between Annual Basin Mean Rainfall and Annual Runoff Depth of Various River Basins in Sumatra JICA Project for the Master Plan Study of F-19 August, 211

84 Final Report (Supporting_PreF/S) Figure 21 Concept of Composite Tank Model JICA Project for the Master Plan Study of F-2 August, 211

85 Final Report (Supporting_PreF/S) 1982/1 1982/7 1983/1 1983/7 1984/1 1984/7 1985/1 1985/7 1986/1 1986/ Rain Observed Runoff Simulated Runoff Figure 22 Comparison of Observed and Simulated Monthly Runoff at Sipisang AWLR Station JICA Project for the Master Plan Study of F-21 August, 211

86 Final Report (Supporting_PreF/S) % Observed Runoff (m3/s) Simulated Runoff (m3/s) Error % % 5% % 1% % 15% % 2% % 25% % 3% % 35% % 4% % 45% % 5% % 55% % 6% % 65% % 7% % 75% % 8% % 85% % 9% % 95% % 1% % Observed Runoff Simulated Runoff % 1% 2% 3% 4% 5% 6% 7% 8% 9% 1% Discharge (m3/s) Figure 23 Flow Duration Curve of Observed and Simulated Monthly Runoff at Sipisang AWLR Station JICA Project for the Master Plan Study of F-22 August, 211

87 Final Report (Supporting_PreF/S) 1973/1 1974/1 1975/1 1976/1 1977/1 1978/1 1979/1 198/1 1981/1 1982/1 1983/1 1984/1 1985/1 1986/1 1987/1 1988/1 1989/1 199/1 1991/1 1992/1 1993/ Rain Observed Runoff Simulated Runoff Figure 24 Simulated Long-term Monthly Runoff at Sipisang AWLR Station JICA Project for the Master Plan Study of F-23 August, 211

88 Final Report (Supporting_PreF/S) % Observed and Simulated Runoff (m3/s) % % % % % % % % % % % % % % 16. 7% % % % % % % 6.78 average Observed and Simulated Runoff Discharge (m3/s) Figure 25 Flow Duration Curve of Estimated Monthly Runoff at Sipisang AWLR Station JICA Project for the Master Plan Study of F-24 August, 211

89 Final Report (Supporting_PreF/S) Probability Estimated Runoff (%) (m3/s) % % % % % % % % % % % % % % % % % % % % 1.3 1% 6.32 Average Masang-2 Intake Weir Site Probability of Exceedence Runoff (m3/s) Figure 26 Flow Duration Curve of Estimated Daily Runoff at Masang-2 Intake Weir Site JICA Project for the Master Plan Study of F-25 August, 211

90 Final Report (Supporting_PreF/S) Figure 27 Location Map of Water Level Observation and Discharge Measurement JICA Project for the Master Plan Study of F-26 August, 211

91 Final Report (Supporting_PreF/S) 2. Maximum Water Level 2.1m 21/11/26 6: 1.5 Water Level (m) 1. Average Water Level.75m.5 Minimum Water Level.55m 21/12/23. 21/1/1 21/1/16 21/1/31 21/11/15 21/11/3 21/12/15 21/12/ Maximum Runoff m3/s 21/11/26 6: 14 Runoff (m3/s) Average Runoff m3/s Discharge Measurement Estimated Runoff with H-Q Rating Curve Minimum Runoff 13.6 m3/s 21/12/ /1/1 21/1/16 21/1/31 21/11/15 21/11/3 21/12/15 21/12/3 Figure 28 Result of Water Level Observation and Hydrograph Calculated with H-Q Rating Curve JICA Project for the Master Plan Study of F-27 August, 211

92 Final Report (Supporting_PreF/S) Q=36.55(H+.6)^ Water Level (m) Observation H-Q Rating Curve Discharge (m3/s) Figure 29 H-Q Rating Curve JICA Project for the Master Plan Study of F-28 August, 211

93 Final Report (Supporting_PreF/S) Number of Data % 5% 13% Total Rainfall Depth >= 5mm 29% 48% 63% 73% 84% 87% 89% 94% Time Duration (Hour) 1% 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Number of Data % Total Rainfall Depth >= 1mm 4% 8% 8% 8% 8% 8% % % % Time Duration (Hour) 1% 1% 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Figure 3 Histogram of Rainfall Duration JICA Project for the Master Plan Study of F-29 August, 211

94 Final Report (Supporting_PreF/S) 1% 9% 8% 7% Accumulated Rainfall (%) 6% 5% 4% Design Pattern 5% Design Hyetograph 3% 2% Rainfall (%) 4% 3% 2% 1% 1% % Time (hour) % Time (hour) Figure 31 Accumulated Hourly Rainfall Pattern around Masang River Basin and Design Hyetograph JICA Project for the Master Plan Study of F-3 August, 211

95 Final Report (Supporting_PreF/S) Area Reduction Factor Point Rainfall Depth (mm) Figure 32 Area Reduction Factor for Masang River Basin JICA Project for the Master Plan Study of F-31 August, 211

96 Final Report (Supporting_PreF/S) Figure 33 Frequency Curves of Probable Daily Rainfall at Payakumbuh station JICA Project for the Master Plan Study of F-32 August, 211

97 Final Report (Supporting_PreF/S) Length of record (years) X n adjustment factor (%) X n-m / X n Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Page 97, World Meteorological Organization, 1973 Figure 34 Adjustment of Mean of Annual Series for Maximum Observed Rainfall JICA Project for the Master Plan Study of F-33 August, 211

98 Final Report (Supporting_PreF/S) Length of record (years) S n adjustment factor (%) S n-m / S n Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Page 98, World Meteorological Organization, 1973 Figure 35 Adjustment of Standard Deviation of Annual Series for Maximum Observed Rainfall JICA Project for the Master Plan Study of F-34 August, 211

99 Final Report (Supporting_PreF/S) Adjustment Factor (%) Standard Deviation 15 Mean Length of Record (years) Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Page 99, World Meteorological Organization, 1973 Figure 36 Adjustment of Mean and Standard Deviation of Annual Series for Length of Record JICA Project for the Master Plan Study of F-35 August, 211

100 Final Report (Supporting_PreF/S) 2 15 K m 1 5 min 6 hours Duration 24 hours 1 hour Mean Annual Rainfall (mm) Figure 37 Km as a Function of Rainfall Duration and Mean of Annual Series Adjustment Factor Number of Observational Units Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Pages 96 &1, World Meteorological Organization, 1973 Figure 38 Adjustment of Fixed Interval Precipitation Amounts for Number of Observational Units within the Interval JICA Project for the Master Plan Study of F-36 August, 211

101 Final Report (Supporting_PreF/S) 3, Slope 2,5 Height (m) 2, 1,5 1, 5 - Tc=5.8hr Tc=.4hr - 1, 2, 3, 4, 5, 6, Distance (m) Figure 39 Slope of Masang River 25 2 Discharge (m3/s) Time (hour) Figure 4 SCS Unit Hydrograph at Masang-2 Intake Weir Site JICA Project for the Master Plan Study of F-37 August, 211

102 Final Report (Supporting_PreF/S) Daily Runoff Record as Sipisang Station Dischatge (m3/s) 1982/1/1 1982/2/1 1982/3/1 1982/4/1 1982/5/1 1982/6/1 1982/7/1 1982/8/1 1982/9/1 1982/1/1 1982/11/1 1982/12/1 1983/1/1 1983/2/1 1983/3/1 1983/4/1 1983/5/1 1983/6/1 1983/7/1 1983/8/1 1983/9/1 1983/1/1 1983/11/1 1983/12/1 1984/1/1 1984/2/1 1984/3/1 1984/4/1 1984/5/1 1984/6/1 1984/7/1 1984/8/1 1984/9/1 1984/1/1 1984/11/1 1984/12/1 1985/1/1 1985/2/1 1985/3/1 1985/4/1 1985/5/1 1985/6/1 1985/7/1 1985/8/1 1985/9/1 1985/1/1 1985/11/1 1985/12/1 1986/1/1 1986/2/1 1986/3/1 1986/4/1 1986/5/1 1986/6/1 1986/7/1 1986/8/1 1986/9/1 1986/1/1 1986/11/1 1986/12/1 Figure 41 Daily Runoff Hydrograph at Sipisang AWLR Station JICA Project for the Master Plan Study of F-38 August, 211

103 Final Report (Supporting_PreF/S) Time (hour) PMF Discharge (m3/s) Figure 42 Probable Flood Hydrographs at Masang-2 Intake Weir Site JICA Project for the Master Plan Study of F-39 August, 211

104 Final Report (Supporting_PreF/S) 1, Probable Maximum Flood Flood Peak Discharge (m3/s) 1, 1, 1 PMF C=92 Masang-2 PMF , 1, 1, Catchment Area (km2) 1, Return Period = 2 year Flood Peak Discharge (m3/s) 1, 1, 1 2 C=28 Masagn , 1, 1, Catchment Area (km2) Figure 43 Relationship between Probable Peak Discharge and Catchment Area in Sumatra (1/3) JICA Project for the Master Plan Study of F-4 August, 211

105 Final Report (Supporting_PreF/S) 1, Return Period = 1 year Flood Peak Discharge (m3/s) 1, 1 1 C=25 Masagn , 1, 1, Catchment Area (km2) 1, Return Period = 2 year Flood Peak Discharge (m3/s) 1, 1 2 C=19 Masagn , 1, 1, Catchment Area (km2) Figure 44 Relationship between Probable Peak Discharge and Catchment Area in Sumatra (2/3) JICA Project for the Master Plan Study of F-41 August, 211

106 Final Report (Supporting_PreF/S) 1, Return Period = 2 year Flood Peak Discharge (m3/s) 1, 1 2 C=1 Masagn , 1, 1, Catchment Area (km2) Figure 45 Relationship between Probable Peak Discharge and Catchment Area in Sumatra (3/3) JICA Project for the Master Plan Study of F-42 August, 211

107 Final Report (Supporting_PreF/S) Figure 46 Catchment Area of Regulating Pond based on 1:1, Map JICA Project for the Master Plan Study of F-43 August, 211

108 Final Report (Supporting_PreF/S) Masang-2 Basin 443. km 2 Alahanpanjang Basin km 2 B. A. Alahanpanjang Intake Weir Site B. Masang Sub Basin 52.4 km 2 Power House Site Figure 47 Catchment Area of Power House Site based on 1:25, Map JICA Project for the Master Plan Study of F-44 August, 211