for the corresponding author: Abstract-- This work aims to long-term estimate water loss

Transcription

1 International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: Long-Term Estimation of Water Losses Through Evaporation from Water Surfaces of Nasser Lake Reservoir, Egypt Ali M. Hamdan* and Mohamed Zaki** *Geology Department, Faculty of Science, Aswan University, Aswan, Egypt. **Egyptian environment affairs Agency, Aswan, Egypt. for the corresponding author: Abstract-- This work aims to long-term estimate water loss through evaporation from an open water surfaces of Aswan High Dam Reservoir (AHDR) using of local hydrological and meteorological data collected from instrumented platforms at nine locations: front of High Dam, Kohr Kalbshka, Wadi abud north Allaqi, Almalka, Amada, Kohr Toshka, Toshka, Abu Simple, and Argeen. Bulk Areodydimic method applied using monthly available hydrometeorological data with longest data record of the last 20 years (from water year 1995/1996 to 2014/2015). Water losses by evaporation vary from m 3 (in 1995/1996) to m 3 (in 2007/2008) with an average of m 3 /year. Water budget is another method used to estimate evaporation losses for the past 5 decades (last 51 years) from 1964, after the construction of the High Dam and before forming Nasser Lake reservoir till now. The relationships between water losses by evaporation, lake water level, inflow arriving the lake, and changes of the lake water storage were detected and show many variations. Percentage of evaporation relative to water storage in the lake vary from 3.55% to 20.26%, with an average of 10.94%; and it ranges between 0.24% and 21.18% with average of 12.65% relative to the water income to the lake. Index Term-- Nasser Lake, evaporation loss, Bulk Areodydimic, hydrometeorology. 1- INTRODUCTION Water distribution throughout the world is not homogeneous. In many places, the majority of populace does not have adequate amounts of fresh water. The industrial developments, population growth, rising in energy demand, increasing the quality of life standards, and agriculture irrigations have resulted in the importance increasing for fresh water resources. In arid and semi-arid regions, the evaporation water loss from open-water reservoirs is one of the national problems and it is a big problem throughout the World. Along the world, evaporation loss values vary from reservoir to other and change according to change in hydrometerological data. It considered as one of the obscure components of the hydrologic cycle as well as it is one of the main components in both the water budgets and energy of lakes and a primary process of water loss for most of them. Many literatures estimate of the evaporation loss rates in many parts using different methods. For example, the evaporation losses calculated from open water reservoirs in South-East Queensland (Australia), and it losses about 40% of their total water storage capacity per year [1]. At Sparkling Lake, northern Wisconsin (USA), the mean evaporation loss rate estimated and it is 3.1 mm/day [2]. In tropical Africa lake (Lake Ziway, Ethiopia), the evaporation rate is 4.87 mm/day [3]. Using the energy budget method, evaporation from Williams Lake (North Central Minnesota) varied from 2.82 mm/day to 2.19 mm/day [4]. In Okeechobee Lake (South Florida), the evaporation estimated and it is 3.6 mm/day [5]. In Turkey, the total evaporation loss from water surfaces of reservoirs and lakes estimated and it is m 3 /year from reservoirs and m 3 /year, m 3 /year from lakes [6]. Evaporation from the second largest lake in Japan (Kasumigaura Lake) estimated for 2008 to 2012, the mean annual E is 911 mm [7]. Many methods are used for evaporation losses estimation from open water surfaces including: water budget methods (e.g. [8, 9, and 10]) and the bulk aerodynamic method such as (e.g. [2, 7, and 11]). Aswan High Dam Reservoir (AHDR) consider as one of the largest artificial water reservoirs of the world. It extends along the Nile River, of which one-third about 150 Km (called Nubia Lake) is in Sudan and two-thirds about 350 Km (known as Nasser Lake) is in Egypt [12]. Nasser Lake lies between latitudes 22 o 00` to 23 o 58` N and longitudes 30 o 07` to 33 o 15` E and lies in the extreme southern part of Egypt behind the Aswan High Dam (Figure 1). This study worked on the Egyptian part of the lake (Nasser Lake), where its surface area is changing according to the annual amount of flood and the water discharges from the lake. The shoreline of Nasser Lake reservoir at 180 m level is 7875 Km length and at 160 m level is 5416 Km. The surface area of its entire reservoir at water level of 160 m is 3084 Km 2, when the reservoir is nearly full (at water level of 180 m) it has a surface area of about 6276 Km 2 [13]. The total capacity of the Nasser Lake reservoir is m 3 at the level 182 m. It has an average depth of 25 m, maximum depth of 90 m, average width of 10 km, and maximum width of 60 km [14]. Nasser Lake considered as the fresh and renewable water bank of Egypt and it is important for drinking water, irrigation, hydropower, and fishing. A review of various studies on evaporation losses in Nasser Lake as, the evaporation losses estimated at 2050 using data of

2 International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: and hydrogeological data were monitored and calculated for different times and used many methods. 3 raft stations due to the expected climate changes [15]. Annual evaporation stated for only period from1995 to 2004 based on data from three floating stations and it is 12.1 BCM [16]. The evaporation calculated based on GIS and remote sensing data in one month only (March 2002) and gave evaporation values vary from 2.73 to 9.58 mm/day [17]. Evaporation losses estimated using data from only two raft stations (one raft in 2011 and other in 2010) using neural network and gave annual evaporation rate 7.64 mm/day [18]. Evaporation losses calculated in 2008 using remote sensing (satellite imagery) and gave values vary from 12.5 to 16.3 billion m 3 that year [19]. Evaporation estimated based on remote sensing using Landsat images in only 2 years (from October 1998 to October 2000), and gave evaporation value is 1.5 mm/day [20]. 2- THE OBJECTIVE OF STUDY Nasser Lake is located in an arid region so, estimation of water that losses by the evaporation is quite interest and essentially for determination of the water budget of Egypt. Water shortage in the arid regions along the world is an existing and future severe problem. Egypt has a limited budget of 55 Bm 3 /year from basin of Nile River that has always been stored in AHDR. So that, the main objective of the present study summaries as: - Long-term estimation of water losses through evaporation from an open water surfaces of Aswan High Dam Reservoir (AHDR) or Nasser Lake Reservoir applying Bulk Areodydimic method using monthly collecting and available hydrometeorological data with the longest data record of the last 20 years (from water year 1995/1996 to 2014/2015) depend on local meteorological and hydrological data collected from instrumented platforms (floating weather stations) at nine locations on the lake (Figure 1). - Estimate evaporation loss applying another method (water budget method) from AHDR for the last 51 years from 1964 (since construction of the High Dam and before forming Nasser Lake reservoir) till now. - More than study of evaporation loss, present work includes studying the water budget, for the past 5 decades, in one of the largest man made water reservoirs of the world (AHDR), which considered as one of the main components of studying the Egypt fresh water budget. - The relationship between the evaporation losses from the lake and the change in its water level values were discussed. Also the relationship between E-values, the inflow arriving the Lake (V in ), and the change of water storage in Nasser Lake reservoir ( S) were studied. - It is necessary to study the percentage of E-values relative to the water storage in AHDR; and relative to the water income to the lake. 3- MATERIAL AND METHODS To long-term estimate the amount of water lost by evaporation from Nasser Lake, many hydrometeorological 3.1- Meteorological Stations and Data sources In the present work, the hydrometeorological data obtained from the instrumented platform (floating weather stations) which installed along Nasser Lake and carried out for recording four meteorological parameters as follows: 1- Relative humidity (%). 2- Surface water temperature ( C). 3- Air temperature ( C). 4- Wind velocity (m/sec). These data were recorded daily by (High and Aswan Dam Authority) from which the average monthly was calculated from the 9 raft meteorological stations. They have been installed along the Nasser Lake, from the High Dam to the southern borders of Egypt, in order to measure the meteorological parameters. The obtained data were used for long-term estimation of water evaporation losses. These 9 stations are described in the following (Figure 1): 1- Raft meteorological station in front of High Dam. 2- Kohr Kalbshka raft station (40 km from HD). 3- Wadi abud north Allaqi station (75 km from HD). 4- Almalka raft station (155 km from HD). 5- Amada raft station (185 km from HD). 6- Kohr Toshka raft station (230 km from HD). 7- Toshka raft station (240 km from HD). 8- Abu Simple raft station (280 km from HD). 9- Argeen raft station (331 km from HD). The meteorological data were collected from the 9 raft meteorological stations for the last 20 years from water year 1995/1996 to 2014/2015 were used for calculation of water losses by evaporation using the Bulk Areodydimic method. The water year start from August (began of flooding period) and ended by July. These data. The surface water inflow (10 9 m 3 /year) arriving the Nasser Lake reservoir (V in ) and the discharge downstream through Aswan and High Dams (V out ) were measured by High and Aswan Dam Authority. Diversions or seepage loss from lake water to adjacent Nubian aquifer (10 9 m 3 /year) were calculated by [21]. The water budget method applied using the available hydrological data to calculate the evaporation losses from Nasser Lake reservoir for the last 51 years from water year 1964/1965 till now (2014/2015); i.e. after the construction of the High Dam ( ) and before forming Nasser Lake reservoir Methods of estimations The most common procedures and methods which used for computing the amount of evaporation losses depend on theoretical analyses. Whereas others, as the present work, based on the atmospheric elements and the hydrometerological data applied below using for long-term estimation of water losses through evaporation from water surfaces of Nasser Lake Reservoir. Two methods used: a)- Bulk Areodydimic method and b)- water budget method Bulk Areodydimic method

3 International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: Nasser Lake is located in subtropical and arid zone. According to the meteorological data, the rainfall is nearly rare. Therefore, the above equation can be re-written as: E = V in V out S D... (8) Bulk Aerodynamic method considered as the most widely used for evaporation losses determination from large reservoirs and lakes. The calculations by this method were applied using Harbeck equation [22]. The following formulas and parameters were used for calculation: a- Saturation vapor pressure (es) calculation (1) Where: es is the saturated vapor pressure at water surface (kpa) and WST is the water temperature ( o C). b- Saturated vapor pressure of air calculation (2) Where: ESA is saturated vapor pressure of air (kpa) and AT is air temperature ( o C) at 2 m above water surface. c- Actual vapor pressure calculation... (3) Where: ea is the actual vapor pressure of the air (kpa) and RH is the relative humidity. d- Estimating evaporation from reservoir According to Harbeck equation [22], the evaporation from Nasser Lake reservoirs estimated using the following equation:.... (4) Where: E is the evaporation losses (mm/hour and then accumulated mm/day), U 2 is the wind speed (m/sec) at 2 m height above water surface, N is a coefficient related to the reservoir surface area, ea is the is actual vapor pressure of the air (kpa), and es is the saturated vapor pressure (kpa) at water surface temperature Water budget method This method can provide a most acceptable estimation of evaporation losses. All components used in this method are accurately modeled and/or measured, which each of them is often a difficult task, especially for water seepage losses [2]. The water balance as generally applied to the hydrologic cycle is actually statement of the law of conservation of mass. It based upon the hydrologic equation as following: Inflow = Outflow + Storage... (5) This method depends on monitoring the change which can occur in the reservoir content or water storage of the lake over a certain period of time. Water inflow consist of water runoff along basins, total water precipitation, diversions from outside its basin into the lake, major channels inflow from outside drainage basin, and groundwater inflow. Outflow consist of water evaporation, groundwater flow from the reservoir, diversions out of the water body, and major channel flow out of the water body. Thus, the hydrological budget of the reservoir and water balance equation can be expressed as: V in + Pr = E + V out + S + D... (6) Then, the equation no. (6) can be expressed in terms of E as: E = Pr + V in V out S D... (7) Where: E is evaporation volumetric rate of water from the lake surface (10 9 m 3 /year). V in is lateral inflow of surface water into the water balance area, V out is lateral outflow from the water balance area, D is diversions or seepage loss from lake water to adjacent Nubian aquifer, S is the change in water storage of the lake, and Pr is direct precipitation on the lake water surface. 4- RESULTS AND DISCUSSIONS In the present work, the long-term estimation of water losses through evaporation from water surfaces of Nasser Lake Reservoir performed based on the hydrometerological data and the atmospheric elements by applying two methods: 1- Bulk Areodydimic method and 2- water budget method Calculation of water losses by evaporation using Bulk Areodydimic method. This method depends on immediate measurements of the factors and elements which affecting the evaporation losses, such as air and water temperatures, wind speed, and relative humidity. In this work, to estimate the amount of water lost by evaporation from Nasser Lake using Bulk Areodydimic method, many hydrometeorological and hydrogeological data were collected from the 9 raft meteorological stations (instrumented platform floating weather stations) installed along the Nasser Lake, from the High Dam to the southern borders of Egypt (Figure 1). The 9 raft meteorological stations recorded daily relative humidity (%), wind velocity at height 2 m above water surface (m/sec). water temperature ( C), and the air temperature at 2 m above water surface. The meteorological data were collected for the last 20 years from water year 1995/1996 to 2014/2015 to calculate E-values using this method through applying the Equations (nos. 1 to 4) (Table 1 and Figure 2). Many parameters were computed before calculating the E- values as: a)- Saturated vapor pressure of air (ESA), b)- Saturation vapor pressure (kpa) at water surface temperature (es), and c)- Actual vapor pressure of the air (ea). The E-values (Table 1) vary from year to anther and range between m 3 (calculated during 1995/1996) and m 3 (estimated in 2007/2008) with an average of m 3 / year. Along the study reservoir, the daily total evaporation was best described as a function of the vapor pressure difference between the water surface and atmosphere, as well as it affected by the horizontal wind speed. The relationship between the calculated values of water losses by evaporation from Nasser Lake and the change in its water level values from 1995 to 2015 shows a slightly direct relation (Figure 3). The calculated evaporation loss values by applying the Bulk Areodydimic method is changeable. The E-values increase from 1995/1996 to 1998/1999 then start to decrease till the water year 2005/2006. After that time, the evaporation

4 Evaporation (10 9 ) International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: losses increase to water year 2007/2008 then decrease again down) in recent years. (2009/2010), after that E-values change irregularly (up and Fig. 1. Location map of the hydrometerological floating station along Nasser Lake Comparing between the change of E-values in summer, autumn, winter, and spring from water year 1995/1996 to 2014/2015 are shown in Figure (4). At the same year, the water losses by evaporation from Nasser Lake are not stable, but vary from month to other. Evaporation rates show an attribute of annual cycle with highest values at summer, where the air temperature at 2 m above water surface (AT), the water temperature (WST), the saturated vapor pressure of air (ESA), and the saturated vapor pressure at water surface (es) at the study area have high values at July, August, and September months. These parameters are directly affected to the E-values. Autumn and spring come after summer, in E-values, due to present moderate values of the mentioned parameters. Finally, the low E-values estimated in winter at January, February, and March months because the previous parameters have low values comparing with other months along the same year Monthly evaporation loss (from 1995/1996 to 1999/2000) AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL 1995/ / / / /2000

5 Evaporation (10 9 ) Evaporation (10 9 ) Evaporation (10 9 ) International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: Monthly evaporation loss (from 2000/2001 to 2004/2005) AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL 2000/ / / / / Monthly evaporation loss (from 2005/2006 to 2009/2010) AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL 2005/ / / / /2010 Monthly evaporation loss (from 2010/2011 to 2014/2015) AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL 2010/ / / / /2015 Fig. 2. Monthly average of water losses by evaporation for period from 1995 to Table I Water losses by evaporation using hydrometerological data calculated by applying the Bulk Areodydimic method from 1995 to August September October November December January February March April May June July Minimum Maximum Average Total

6 Evaporation (10 9 ) evaporation(10 9 ) water level m International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: Table I Continue August September October November December January February March April May June July Minimum Maximum Average Total Evaporation loss (BCM) Lake water level Fig. 3. Relation between water losses by evaporation and lake water level Fig. 4. Comparing between the change of E-values in summer, autumn, winter, and spring Calculation of water losses by evaporation using water budget method All water balance equations are principally based on the difference between water outflow and water inflow over a period of time for the hydrologic system of a reservoir and must equal the change in water storage. The water balance or the hydrological budget of the Nasser Lake, as well as the water losses by evaporation, can be calculated from different Summer Autumn Winter Spring parameters using Equation no. 8 (seepage loss from lake water to adjacent Nubian aquifer, change in water storage, and inflow of and outflow from the lake). The imaginary of water budget of Nasser Lake reservoir is shown in Figure (5). This method can be assessed for any period of time, for any of hydrologic cycle subsystem, and for any basin area. It can apply to check all storage and flow components involved with quantitatively estimation. It can serve to calculate with

7 International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: that, the evaporation loss values from Nasser Lake as calculated by this method is not consistent. Whereas, the water losses by evaporation increase in the period from 1964/1965 to 1975/1976 then start to decrease till the water year 1987/1988. After that time, the evaporation losses increase significantly to water year 1998/1999 then start to decrease again in recent years. sufficient accuracy the one unknown component of the balance equation, concerned that the other components are known. The discharge downstream through Aswan and High Dams (V out ) and the surface water inflow arriving the Nasser Lake reservoir (V in ) were measured by High and Aswan Dam Authority. Diversions or seepage loss from lake water to adjacent Nubian aquifer (10 9 m 3 /year) were calculated from [21]. The available hydrological data used to calculate the losses from Nasser Lake reservoir by the water budget method for the last 51 years from water year 1964/1965 till now (2014/2015), i.e. after the construction of the High Dam ( ) and before forming Nasser Lake reservoir. The water losses by evaporation from Nasser Lake which calculated by the water balance method using Equation (no. 8) are shown in Table (2) and Figure (6). The E-values vary from 0.29 estimated in 1964/1965 to calculated in 1975/1976 with an average of (10 9 m 3 /year). The surface water inflow arriving the Nasser Lake reservoir (V in ) reached its maximum in 1964/1965 and 1975/1976 ( and respectively). The minimum (V in ) is recorded in 1984/1985. The average of (V in ) is (10 9 m 3 /year). The change in water level values in Nasser Lake from 1964/1965 to 2014/2015 (Table 2) and the calculated values of water losses by evaporation from lake at the same period of time were used to determine the relationship between them (Figure 6). It shows a slightly direct relation. It can be seen This inconsistency in the evaporation losse values of Nasser Lake as shown in Figures (6 and 7) is related to the annual change of its water budget which is affected by many hydrological parameters (seepage loss from lake water, the change in water storage, and volume of water inflow of and outflow from the lake reservoir). The annual change in water storage in Nasser Lake reservoir ( S) also considered as one of the important component for assessing of the water budget or estimation the water balance, as well as in calculating values of the evaporation losses. It calculated using the volume of water storage in the Lake every year for the last 51 years from 1964/1965 till now (Table 2). The average annual change in water storage in Nasser Lake reservoir ( S) is 2.04 (10 9 m 3 /year), while the minimum is calculated in 1984/1985 and the maximum is detected in 1988/1989. The relationship between the change of water storage in the lake ( S), water losses by evaporation (E) using this method, and the inflow arriving the lake (V in ) were examined for the last 51 years (Figure 7). It is a slightly direct relation between the three variables along Nasser Lake reservoir. Fig. 5. The imaginary of water budget of Nasser Lake reservoir.

8 Vin and Change in water storage (BCM) Evaporation Losses (BCM) Evaporation Losses (BCM) watel level m International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: Evaporation loss Water level Linear ( Evaporation loss) Fig. 6. Water losses by evaporation using water budget method and their relation with lake water level Inflow arriving the Lake Change in water storage of the Lake Evaporation loss Fig. 7. Relationship between the water losses by evaporation (E), the volume of water inflow (V in), and the change in the water storage ( S) of the Lake (10 9 m 3 /year) The percentages of water lost by evaporation E-values relative to water storage in the lake It is necessary to know the percentage of the water storage in the Nasser Lake reservoir (fresh and renewable water bank of Egypt) relative to water loss by evaporation as a main component for determination the water budget of Egypt. The estimated percentage of the water storage in the lake relative to water lost by evaporation were examined as shown in Figure (8). The maximum water storage in the lake reaches billion cubic meters recorded in 2000/2001, while the minimum value is 3.33 estimated in 1964/1965 and contains average billion cubic meters from fresh water (Table 2). The obtained percentage values vary from 3.55% (recorded during year 1992/1993) to 20.26% (appeared during year 1965/1966), with an average of 10.94% (Table 2) Percentage of E-values relative to the water income to the lake Also it is very important to calculate the percentage of water loss by evaporation relative to water income to the lake (Figure 9). The percentage of evaporation loss relative to V in or total of (E + V out + S + D) were calculated from equation 9 or 10 (Table 2). (9)...(10) The average of this percentage is 12.65% and the maximum percentage value is 21.18% detected at 1976/1977 while the minimum values recorded at the first three years from forming Nasser Lake reservoir.

9 V. Water storage (BCM) E% relative to water storage International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: % 20% % 10% 50 5% 0 0% Fig. 8. Percentage of water lost by evaporation relative to the water storage in the lake Table II Water losses by evaporation from Nasser Lake reservoir along period of time from 1964/1965 to 2014/2015 as calculated by the water budget method. Water year Water storage in the Lake (BCM) Flow arriving the Lake Water storage in the Lake Change of water storage in the Lake Discharge downstre am from HAD Nasser Lake water level (m) E% relative to water storage in the lake Water seepage loss Water losses by evaporation Percent of evaporation loss/total V in or total V out Percent of evaporation loss/water storage in the Lake 1964/ % 8.58% 1965/ % 20.26% 1966/ % 14.52% 1967/ % 20.12% 1968/ % 17.96% 1969/ % 19.38% 1970/ % 14.72% 1971/ % 18.63% 1972/ % 17.45% 1973/ % 15.08% 1974/ % 14.88% 1975/ % 19.28% 1976/ % 13.53% 1977/ % 9.90% 1978/ % 9.40% 1979/ % 7.13% 1980/ % 9.75% 1981/ % 11.74% 1982/ % 11.66% 1983/ % 12.15% 1984/ % 12.86% 1985/ % 11.12% 1986/ % 8.41% 1987/ % 4.74% 1988/ % 10.32% 1989/ % 11.12% 1990/ % 11.79% 1991/ % 8.01% 1992/ % 3.55% 1993/ % 10.67% 1994/ % 9.43% 1995/ % 7.30%

10 Flow Arriving the Lake (BCM) E% relative to water income International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: / % 7.34% 1997/ % 8.36% 1998/ % 13.98% 1999/ % 8.47% 2000/ % 9.06% 2001/ % 6.90% 2002/ % 9.22% 2003/ % 6.33% 2004/ % 8.82% 2005/ % 7.55% 2006/ % 6.67% 2007/ % 6.80% 2008/ % 12.17% 2009/ % 11.15% 2010/ % 7.25% 2011/ % 9.82% 2012/ % 7.87% 2013/ % 6.60% 2014/ % 8.27% % 20% 15% 10% 5% 0% Flow Arriving the Lake(BCM) Fig. 9. Percentage of water lost by evaporation relative to the water income to the lake 5- CONCLUSIONS long-term estimation of water losses through evaporation from water surfaces of Nasser Lake Reservoir performed by applying two methods. Bulk Areodydimic method used to estimate evaporation losses the last 20 years from 1995/1996 to 2014/2015 through collecting hydrometeorological and hydrogeological data from 9 raft meteorological stations installed along the Lake, from the High Dam to the southern borders of Egypt. The rate of evaporation using this method is m 3 / year and evaporation losses vary from m 3 (calculated during 1995/1996) to m 3 (estimated in 2007/2008). At the same year, the water losses by evaporation are not stable and show highest values at summer, where (AT), (WST), (ESA), and (es) have high values at July, August, and September months. The water budget method applied to calculate the evaporation losses for the last 51 years from 1964/1965 till now (2014/2015). The E-values as calculated by this method vary from 0.29 estimated in 1964/1965 to E% relative to water income to the lake calculated in 1975/1976 with an average of (10 9 m 3 /year). The relationship between water losses by evaporation and the change in water level of the lake shows a slightly direct relation with some changes and fluctuations. The relationship between the change of water storage in the lake ( S), the evaporation losses (E) using water budget method, and the inflow arriving the lake (V in ) were examined and show a slightly direct relation between the three variables. The estimated percentage of the water storage in the lake relative to water lost by evaporation were examined and its values vary from 3.55% (recorded in 1992/1993) to 20.26% (detected in 1965/1966), with an average of 10.94%. Also, the percentage of evaporation losses relative to water income to the lake calculate. The average of this percentage is 12.65% and the maximum value is 21.18% detected at 1976/1977 while the minimum values recorded at the first three years from forming Nasser Lake reservoir. 6- ACKNOWLEDGMENT The authors would like to acknowledge and very grateful to

11 International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 16 No: [20] Hassan, M. (2013) Evaporation estimation for Lake Nasser based on remote sensing technology. Ain Shams Engineering Journal, 4(4), [21] Hamdan, A., Selim, S., and Zaki, M. (2015) Estimation of seepage loss from Nasser Lake to the adjacent Nubian sandstone aquifer, southern Egypt. International Journal of Science and Research, 4(9), [22] Harbeck Jr., G.E. (1962) A Practical Field Technique for Measuring Reservoir Evaporation Utilizing Mass-transfer Theory, U.S. Geol. Surv., 272-E, High and Aswan Dams Authority for providing meteorological data and their cooperation throughout the research. REFERENCES [1] Helfer, F., Lemckert, C., and Zhang, H. (2012) Impacts of climate change on temperature and evaporation from a large reservoir in Australia. Journal of Hydrology, 475, [2] Lenters, J. D., Kratz, T. K., and Bowser, C. J. (2005) Effects of climate variability on lake evaporation: Results from a long-term energy budget study of Sparkling Lake, northern Wisconsin (USA). Journal of Hydrology, 308(1), [3] Vallet-Coulomb, C., Legesse, D., Gasse, F., Travi, Y., and Chernet, T. (2001) Lake evaporation estimates in tropical Africa (Lake Ziway, Ethiopia). Journal of hydrology, 245(1), [4] Sturrock, A. M., Winter, T. C., and Rosenberry, D. O. (1992) Energy budget evaporation from Williams Lake: A closed lake in north central Minnesota. Water Resources Research, 28(6), [5] Abtew, W. (2001) Evaporation estimation for Lake Okeechobee in south Florida. Journal of Irrigation and Drainage Engineering, 127(3), [6] Gokbulak, F., and Ozhan, S. (2006) Water loss through evaporation from water surfaces of lakes and reservoirs in Turkey. Official Publication of the European Water Association, EWA. [7] Sugita, M., Ikura, H., Miyano, A., Yamamoto, K., and Zhongwang, W. (2014) Evaporation from Lake Kasumigaura: annual totals and variability in time and space. Hydrological Research Letters, 8(3), [8] Mosner, M. S., and Aulenbach, B. T. (2003) Comparison of methods used to estimate lake evaporation for a water budget of Lake Seminole, southwestern Georgia and northwestern Florida. Proceedings of the 2003 Georgia water Resources Conference, April 23-24, Athens, Georgia. [9] Dalton, M.S., Aulenbach, B.T., and Torak, L.J., (2004) Ground-water and surface-water flow and estimated water budget for Lake Seminole, Southwestern Georgia and Northwestern Florida. Scientific Investigations Report , US Geological Survey, Atlanta, GA, USA. [10] Makdessi, M., Rahman, A., and Kibria, G. (2005) Investigation of the thermodynamic component of penman s method for estimating evaporation. In: Zerger A, Argent RM (eds) MODSIM. [11] Yao, H. X. (2009) Long-term study of lake evaporation and evaluation of seven estimation methods: results from Dickie Lake, South-Central Ontario, Canada. Journal of Environmental Protection, 1, [12] Atkins, S., (2002) Comprehensive Development Plan for Aswan and Lake Nasser. UNDP, Ministry for Planning, Aswan Governorate. [13] Jeongkon, K. and Mohamed, S. (2002) Assessment of long-term hydrologic impacts of Lake Nasser and related irrigation projects in Southwestern Egypt. Elsevier Science, Journal of Hydrology, [14] Sadek, M.F., Shahin, M.M., and Stigter, C.J. (1997) Evaporation from the reservoir of the high Aswan dam, Egypt: a new comparison of relevant methods with limited data. Theor Appl Climatol., 56, [15] Badawy, H. A. (2009) Effect of expected climate changes on evaporation losses from Aswan High Dam Reservoir (AHDR), Thirteenth International Water Technology Conference, IWTC , Hurghada, Egypt. [16] Elsawwaf, M., Willems, P., Pagano, A., and Berlamont, J. (2010) Evaporation estimates from Nasser Lake, Egypt, based on three floating station data and Bowen ratio energy budget. Theoretical and applied climatology, 100(3-4), [17] Ebaid, H. M. and Ismail, S. S. (2010) Lake Nasser evaporation reduction study. Journal of advanced research, 1(4), [18] Kalifa, E. A., Abd, R. M., and Alhayawei, S. A. (2012) Estimation of Evaporation Losses from Lake Nasser: Neural Network based Modeling versus Multivariate Linear Regression. Journal of Applied Sciences Research, 8(5), [19] Abou El-Magd, I. H. and Ali, E. M. (2012) Estimation of the evaporative losses from Lake Nasser, Egypt using optical satellite imagery. International Journal of Digital Earth, 5(2),