Remote Sensing and GIS Applications in Determination of Geomorphological Parameters and Design Flood for a Himalyan River Basin, India

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1 International Research Journal of Earth Sciences ISSN Int. Res. Earth Sci. Remote Sensing and GIS Applications in Determination of Geomorphological Parameters and Design Flood for a Himalyan River Basin, India Abstract Himanshu S.K., FISCA, Garg N., Rautela S., Anuja K.M. and Tiwari M. Department of Civil Engineering, GEU, Dehradun, UK, INDIA Available online at: Received 21 st May 2013, revised 30 th May 2013, accepted 15 th June 2013 The most widely and generally applied method for the prediction of flood hydrograph which is derived from a known storm in a basin area uses historical rainfall-runoff data and unit hydrographs derived from them. These technique are highly unreliable because of the physical and climatic changes in the watershed and their implementation to ungauged catchments. These drawbacks can be overcome by making the use of the synthetic unit hydrograph (SUH), which is a physically based rainfall-runoff estimation method. A detailed drainage analysis was done for a 5 th order flood prone Himalayan river. The geomorphological parameters of the basin were estimated from 30 m ASTER (Advanced Space Borne Thermal Emission and Reflection Radiometer Sensor) DEM and Landsat imageries using ARC-GIS 9.3 and ERDAS IMAGINE 9.3 Software. The aim of this study was to estimate the design flood of the site situated at Joshimath, district Chamoli, Uttarakhand along with the few Geomorphological parameters which will provide us with feasibility of designing of the hydraulic structures such as dams in near future in this catchment area. Presented in this paper are the results derived using ArcGIS and ERDAS Imagine on the data acquired. The results shows that more than 50 % of the catchment is snow-fed area hence, the selected site will have a continuous supply of water throughout the year making it a potentially profitable dam site. 1 hour Synthetic Unit Hydrograph peak discharge at site was found to be Cumecs, on the basis of which design flood was estimated considering PMP and peak flood discharge at site was found to be 6188 Cumecs. Keywords: Design flood, geomorphological parameters, digital elevation model (DEM), synthetic unit hydrograph (SUH), probable maximum precipitation (PMP), geographic information system (GIS), remote sensing. Introduction Flood estimation is an integral part of surface water hydrology for comprehensive water resources planning, management and development, including the mitigation and prevention of flood hazards. This has led to the development of a number of conceptual or physically based hydrological modeling approaches by various researchers. The hydrologic response is a function of climate parameters, soil parameters, landuse and topography and therefore, any physical based models requires time to time changes in their parameters because of the variations that are encountered with respect to the gradual landuse and climatic changes of the watersheds 1. It is not possible to observe data at many locations of the catchment or over a long period in a drainage network due to large investments involved in setting up gauging stations. Extensive studies are in progress to relate runoff to geomorphology of the catchment which will overcome the above difficulties as well as the difficulties caused by global atmospheric changes and changes in land use pattern in the catchment. Geomorphology of a river basin describes the status of topographic features of the surfaces and streams, and its relationship with hydrology provides the geomorphological control on basin hydrology 2. Geomorphology describes the geometric and topographic properties of the watershed and its drainage channel network. The subsequent flow routing through the drainage network and hydrologic processes such as rainfall, runoff etc are controlled by it. Earlier works have provided an understanding of basin geomorphology-hydrology relationship through empirical relationships 3-5. For ungauged basin Snyder proposed a synthetic unit hydrograph approach (SUH),as a function of basin shape, catchment area, channel slope, stream density, topography and channel storage; and derived the basin coefficient by taking average of other parameters. The Geomorphological parameters are mostly time-invariant in nature and therefore, geomorphology based approach could be the most suitable technique for modeling the rainfall-runoff process for ungauged catchments. The concept of the geomorphologic instantaneous unit hydrograph (GIUH) was introduced by Rodriguez-Iturbe and Valdes. It was a first step in the direction of coupling the hydrologic characteristics of a catchment with the geomorphologic parameters. The GIUH approach is applicable for ungauged or scantily gauged catchments wherein rainfall data are available but runoff data are not. They can be applied to ungauged basins having scarce hydrologic data 6. The GIUH approach is more advantageous than the conventional IUH methods such as the Clark IUH model and the Nash IUH model since it avoids the requirement of stream flow data 7,8. Also, the parameters of the Clark and Nash IUH models require to be International Science Congress Association 11

2 updated from time to time because of changing land-use and climatic conditions. Further, the GIUH approach is more advantageous than the regionalization techniques as it does not require any information about the other catchments in the hydro meteorologically homogeneous region. Another advantage of GIUH technique is its potential for deriving the unit hydrograph (UH) using the geomorphologic characteristics obtainable from topographic map/remote sensing, possibly linked with geographic information system (GIS) and digital elevation model (DEM) 9,10. However, the GIUH technique is applicable for the estimation of the direct runoff component of the stream flow and hence, can be used to generate the direct runoff hydrograph (DRH). Once the DRH is computed, the flood hydrograph can be simply obtained by adding the base flow component. In synthetic unit hydrograph the term synthetic denotes the unit hydrograph (UH) derived from watershed Characteristics rather than rainfall-runoff data 11,12. The beginning of the synthetic unit hydrograph concept can be traced back to the distribution graph proposed to synthesize the UH from watershed characteristics, rather than the rainfall-runoff data 13,14. Their simplicity and ease in development can characterize these synthetic or artificial unit hydrographs, and require less data and yield a smooth and single valued shape corresponding to one unit runoff volume, which is essential for unit hydrograph derivation. These methods utilize a set of empirical equations relating the physical characteristics of watershed to the few salient points of the hydrograph such as peak flow rate (Q p ), time to peak (t p ), time base (t ), and UH width at 0.5 Q p and 0.75 Q p i.e. W 0.5 and W 0.75, respectively. The objective of the present study was to evaluate the geomorphologic parameters of the catchment by using a geographic information system (GIS) and Remote Sensing using DEM. The geomorphologic parameters are used to derive Synthetic Unit Hydrograph. On the basis of Synthetic Unit Hydrograph, Design flood was estimated using PMP for the study area. Methodology Physiographic Analysis and Estimation of different Geomorphological paramaters: The physiographic analysis of the catchment has been undertaken to ascertain the total catchment area of the basin upto the project site. The analysis has been carried out using Digital Elevation Model (DEM) obtained through Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with 30 m resolution. Morphometric analysis involved the computation of stream number, average stream length and average stream area of different sub-basins of the Himalayan river basin following Strahler s ordering scheme. These parameters were used to determine the Horton s Raito as given in table-1. Three of Horton s ratios namely bifurcation ratio (R B ), stream-lengths ratio (R L ) and stream area ratio (R A ) are unique representative parameters for a given watershed and are fixed values for a given watershed system. Values of bifurcation ratio, the length ratio, and the area ratio in nature are normally between 3 and 5 for R B, 1.5 and 3.5 for R L and 3 and 6 for R A, respectively. Table-1 Geomorphological Paramaters Parameters Definitions Formula Bifurcation Ratio (R B ) Length Ratio (R L ) Area Ratio (R A ) Ration of number of streams Ratio of average length of streams Ratio of average area of streams R B = N u 1 /N u N u = Number of streams of n th order R L = L u / L u 1 L u = average length of stream of u th order R A = A u / A u 1 A u = average basin area of streams of u th order Derivation of SUH Parameters: The Design flood was estimated using unit hydrograph based on Hydro- Meteorological approach. In Hydro-meteorological approach the unit hydrograph and design storm are used for the estimation of design flood. The unit hydrograph at project site has been developed as per Flood estimation report for Western Himalyas, Sub-zone 7, as follows: t p = L L c q p S tp W 75 = L L c S W W R W R T 75 L B LC S W W 75 TM t p Q p q tp p A Where, A [km 2 ] = Total rainfed catchment area upto diversion site, L [km] = Length of longest main stream along the river course, Lc [km] = Length of longest main stream from a point apposite to centroid of the catchment area to the point of study, S [m/km] = Equivalent stream slope, Tr [hr] = Unit duration, tp [hr] = Time from the centre of effective rainfall duration to the peak, Tm [hr] = Time from the start of rise to the peak of U.G, T B = Base width of U.G., qp [m 3 /s/km 2 ] = peak rate of discharge (cumecs/sq.km.), Qp [m 3 /s] = Peak discharge of U.G., W 50 [hr] = Width of U.G. measured at 50% of peak discharge ordinate, W 75 = Width of U.G. measured at 75% of peak (1) (2) (3) (4) (5) (6) (7) (8) (9) International Science Congress Association 12

3 discharge ordinate, WR 50 [hr] = Width of the rising limb of U.G. measured at 50% of peak discharge ordinate, WR 75 [hr] = Width of the rising limb of U.G. measured at 75% of peak discharge ordinate. Data Analysis: The approach presented in the previous section was applied to the Himalyan river basin. The catchment of the study area upto the gauging site (Latitude N and Longitude E) is 4482 km 2 out of which km 2 is snow bound area. The river originates in the Kamet glacier region above Badrinath in the extreme northern part of Chamoli district at an elevation of 7800m. The elevation range in the catchment area varies from 1400 m to 7300 m above mean sea level. To extract the geomorphologic features of the basin, ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Digital Elevation Model (DEM) data was used. The DEM of the river basin from ASTER data set was processed in the ArcGIS 9.3 platform to delineate the basin boundaries and the drainage networks. The stream ordering was carried out using the DEM of the basin using Strahler s scheme followed by establishing the flow direction, flow accumulation etc. The highest order of the catchment was recorded as 4 and the maximum length of the highest order channel is found to be 60.9 km. The DEM and the extracted drainage network of the basin using the ArcGIS are shown in figure-1 and figure-2 respectively. A Satellite image of the study area upto Joshimath is given in figure-3. Geomorphological parameters R B, R L, and R A were calculated for consecutive order channels using Horton s laws. R B, R L, and R A for the whole basin were obtained by averaging the preceding values. The average value of Bifurcation ratio R B = 4.28; Stream length ratio R L = 2.24; and stream area ratio R A =5.96. Results and Discussion On the basis of physiographic analysis the different parameters of SUH were estimated. A = km 2, L = km, Lc = km, S = m /km. The unit hydrograph at project site has been developed as per Flood estimation report for Western Himalyas, Sub-zone 7. The key point ordinates of SUH are tabulated below in table-2. The 1- hour Synthetic Unit Hydrograph (SUH) is obtained from the above parameters as shown in figure-4. Table-2 Key point ordinates for SUH Time (hrs) Discharge (cumecs) Figure-1 Digital Elevation Model of the Study Area USING ASTER Figure-2 Drainage Network of the Basin International Science Congress Association 13

4 Discharge (cumec) International Research Journal of Earth Sciences ISSN Figure-3 Satellite image of the study area upto Joshimath Time (hours) Figure-4 Synthetic Unit Hydrograph at the project site The Probable Maximum precipitation for 1 day was taken as 23.6 cm as suggested by IMD. 24 hour point rainfall was taken as taking a factor of Hourly rainfall was estimated using time distribution co-efficient of cumulative hourly rainfall as per Flood estimation report for Western Himalyas, Subzone 7. Finally design flood was estimated using Synthetic Unit Hydrograph ordinates based on Hydro-Meteorological approach and hourly rainfall derived from PMP. On the basis design discharge at project site was found to be 6188 m 3 /s. Conclusion It was established successfully in this studythat remote sensing and GIS can provide the appropriate plateform for convergent of large volume of multi-disciplinary data 15. Many watersheds of the Indian as well as of developing countries do not have sufficient historical records and detailed watershed information needed for physically based distributed models. In these cases SUH can provide a better solution for flood management programs. The technique of SUH based design flood estimation is very useful in prediction/forecast of the temporal variation of the surface runoff at the outlet of the ungauged basin, which is useful in the hydrologic/environmental engineering applications. The described technique is economical and has high accuracy in determining the flood hydrograph for any basin / catchment (gauged or ungauged) as it uses DEM of the catchment that can be freely accessed from SRTM or ASTER sources. The total catchment of the basin upto project site works out to be 4482 km 2. The snow covered area in the basin is 76.15% (April 2005). On the basis of 1 hour Synthetic Unit Hydrograph the peak discharge at project site was found to be 878.5m 3 /s. On International Science Congress Association 14

5 the basis of PMP the peak flood discharge at Joshimath site is found to be 6188 m 3 /s. References 1. Rodriguez-Iturbe I. and Valdes J.B., The geomorphologic structure of hydrologic response, Water Res. Res., 15(6), (1979) 2. Jain V. and Sinha R., Geomorphological manifestation of the flood hazard, Geocarto International, press-b, (2003) 3. Snyder F.F., Synthetic Unitgraphs, Transactions of American Geophysics Union, 19 th Annual Meeting, 2, 447 (1938) 4. Strahler A.N., Quantitative analysis of watershed geomorphology, Transactions American Geophysical Union, 38, (1957) 5. Horton R.E., Erosional development of streams and their drainage basins: Hydrophysical approach to quantitative morphology, Bull. Geol. Soc. Amer., 56, (1945) 6. Al-Wagdany A.S., Rao A.A., Correlation of the velocity parameter of three geomorphological instantaneous unit hydrograph methods, Hydrological Processes, 12, (1998) 7. Clark C.O., Storage and the Unit Hydrograph, Trans. Am. Soc. Civil Eng., 110, (1945) 8. Nash J.E., A Unit Hydrograph study, with particular reference to British catchments, Proc. Inst. Civil Engg., 17, (1960) 9. Sahoo B., Chatterjee C., RAghuwanshi N.S., Singh R. and Kumar R., Flood estimation by GIUH based Clark and Nash models, ASCE, 11(6), 515 (2006) 10. Kumar R., Chatterjee C., Lohani A.K., Kumar S. and Singh R.D., Sensitivity analysis of the GIUH based Clark model for a catchment, Water Resources Management, 16, (2002) 11. Arora K.R., Irrigation, water power and water resources engineering, standard publishers, Delhi, 1705-B, (2004) 12. Bernard M., An approach to determinate stream flow, Trans ASCE, 100, (1935) 13. Bhunya P.K., Mishra S.K. and Berndtsson R., Simplified two parameter gamma distribution for derivation of synthetic unit hydrograph, J Hydrol Eng ASCE, 8(4), (2003) 14. Singh V.P., Hydrologic systems: Rainfall-runoff modeling, N J Prentice Hall. Englewood, 1, (1988) 15. Biswas A., Jana A. and Sharma S.P., Delineation of Groundwater Potential Zones using Satellite Remote Sensing and Geographic Information System Techniques:A Case study from Ganjam district, Orissa, India, ISCA- Research Journal of Recent Sciences, 1(9), (2012) International Science Congress Association 15