IMPACT OF CLIMATE CHANGE ON RESREVIOR OPERATION POLICIES THE CASE OF ASWAN HIGH DAM RESERVOIR

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1 Inernaional Journal of Civil Engineering and Technology (IJCIET) Volume 7, Issue 2, March-April 2016, pp , Aricle ID: IJCIET_07_02_008 Available online a hp:// Journal Impac Facor (2016): (Calculaed by GISI) ISSN Prin: and ISSN Online: IAEME Publicaion IMPACT OF CLIMATE CHANGE ON RESREVIOR OPERATION POLICIES THE CASE OF ASWAN HIGH DAM RESERVOIR Mohamed Ayman El Salawy Professor a Irrigaion and Hydraulic Deparmen, El Azhar Universiy, Cairo, Egyp Tamer Ali Elgohary Associae Professor a Civil Deparmen CIC (Canadian Inernaional College), Cairo, Egyp Amir Mohamed Akl Mobasher Assisan Professor a Irrigaion and Hydraulic Deparmen, El Azhar Universiy, Cairo, Egyp Mai Mahmmoud Abd El Aziz Assisan Lecurer a Civil Deparmen, Tenh of Ramadan Higher Technological Insiue, Tenh of Ramadan Ciy, Egyp ABSTRACT In 1960 afer he beginning of he consrucion of Aswan High Dam a grea Reservoir (AHDR) was formed as a resul of i for he purposes of flood conrol, hydropower producion and waer sorage. The reservoir is of 550 km long and of 350 km 2 surface area which is locaed on he border beween Egyp and Sudan. The Aswan high dam reservoir (AHDR) is so imporan for Egyp because i represen a safe valve agains draugh and waer needs shorage for counry fuure. Also I conrol he Nile river flood each year o avoid is desrucive damage by sorage he waer exceeding amoun which exceed he Nile river sream capaciy downsream he Aswan high dam. In his research our goal was o sudy he AHDR operaion under he effec of differen scenarios of climae changes, These differen scenarios included rainfall, evaporaion, emperaure, changing waer reservoir level a ( 1m) and inflow o AHDR. This was achieved by using mahemaical model which represen he whole work frame and he reservoir parameers. A he end a se of chars of :frequency curves of annual releases from he AHDR were found for Sensiiviy of waer supply releases, evaporaion losses, Toshka spillway, Hydropower and level variaion o climae change. Also a group of hp:// 107 edior@iaeme.com

2 Mohamed Ayman El Salawy, Tamer Ali Elgohary, Amir Mohamed Akl Mobasher and Mai Mahmmoud Abd El Aziz recommendaions were deduced in order o give he appropriae consrains for operaing AHDR under he expeced climae changes scenarios. Key words: Egyp High Dam, Aswan High Dam Reservoir, Reservoir Operaion Policy, Reservoir Inflow Sensiiviy, Climae Changes Impac. Cie his Aricle: Mohamed Ayman El Salawy, Tamer Ali Elgohary, Amir Mohamed Akl Mobasher and Mai Mahmmoud Abd El Aziz, Impac of Climae Change on Resrevior Operaion Policies The Case of Aswan High Dam Reservoir, Inernaional Journal of Civil Engineering and Technology, 7(2), 2016, pp hp:// 1. INTRODUCTION Aswan high dam was consruced on Nile river a Aswan ciy kilomeer 551 D.S of Assiu Barrage of heigh 111 m from Nile bed and widh of 520 m a boom. As a resul of he dam consrucion which have been sared in 1960 and ended in 1972 a grea reservoir was found upsream he dam. The AHDR occupied an area of 6500 km2 wih highes level behind he dam of 182m. The reservoir of 350 km long from Aswan ciy o Sudan borders and of maximum widh of 35 km. The annual carry over capaciy of he reservoirs is of m 3 per year (Minisry of waer resources and irrigaion, 2005) ]1[.The Aswan high dam and is reservoir were used o produce elecric hydro power and o supply Egyp waer needs which include irrigaion, indusrial aciviies and populaion waer demands. Egyp depends on he Nile river o ge ou 55 m 3 per year which conribue more han 97% of is waer needs. Egyp waer resources are consised from differen sources as shown in he following able (1). Type of Waer Resources Table.1 Egyp waer resources Waer Resources and Exracion in Egyp Quaniy in billion m³ per year Nile River 56.8 Precipiaion 1.8 Fossil Groundwaer Exracion 1 Sea Waer Desalinaion 0.1 Sum 59.7 Reuse of Spilled Waer Resources Renewable Groundwaer Exracion 2.3 Wasewaer Reuse 2.9 Agriculural Drainage Reuse 7.5 Sum 12.7 Climae changes such as emperaure and rain precipiaion has a significan impac on Nile river basin as shown in fig(1) (Srzepek and Yaes, 2000) ]2[. hp:// 108 edior@iaeme.com

3 Impac of Climae Change on Resrevior Operaion Policies The Case of Aswan High Dam Reservoir For example An increase of 10% of average annual precipiaion would lead o an average increase in annual flow of 40%. Similarly, a decrease in 10% in precipiaion would lead o a reducion of he annual flow wih more han 50% (Minisry of waer resources and irrigaion, 2005) [1]. In our sudy we were curious o find he relaion beween climae changes and is effec on AHDR performance. The performance was measured as a funcion of AHDR hydro power and is annual release discharge downsream operaion policy. 2. THE CURRENT RESERVOIR OPERATION POLICY The Minisry of Waer Resources and irrigaion saed AHDR operaion policy consrains as follow: 1. Maximum allowed waer ouflow should no exceed x 10 6 m 3 /day o avoid excessive erosion and bank overopping. 2. The waer levels upsream Aswan High Dam should be kep a m a he beginning of waer year (Augus 1 s ) o fulfill high and low flow requiremens. 3. The minimum allowed waer discharges should be released o fulfill irrigaion, navigaion, drinking and oher requiremens and Sudan absracions (Sadek and Aziz, 2005) [3]. 3. INFLOW AT AHDR The inflow a AHDR as i was recorded by Dongola recording saion in Sudan from year 1910 o year 1994 as shown in fig (2), Fig (2) shows ha he mean flow varied significanly depending upon he period considered, he mean annual flow from (before operaion of AHD) was 2754 m 3 /s (86.86 x 10 9 m 3 ) wih a sandard deviaion of 398 m 3 /s (12.56 x 10 9 m 3 ). The mean annual flow from (afer operaion of AHD), on he oher hand, was 2214 m 3 /s (69.81 x 10 9 m 3 ) wih a sandard deviaion of 443 m 3 /s (13.98 x 10 9 m 3 ) (Yao and Georgakakos, 2003 )[4]. hp:// 109 edior@iaeme.com

4 Mohamed Ayman El Salawy, Tamer Ali Elgohary, Amir Mohamed Akl Mobasher and Mai Mahmmoud Abd El Aziz 4. CLIMATE CHANGE SCENARIOS The climae changes scenarios and is impac on Nile river flow depends on many assumpions as follow: 1. The growing populaion and he expeced reducions of he Nile waer due o compeiion among he easern Nile counries were used o predic AHDR fuure inflow. 2. The weing and drying predicions under increasing demands due o raised emperaure as well were used also o predic AHDR fuure inflow. These assumpions was saed o predic AHDR inflow changes hrough fuure imes, 2025, 2050, 2075, and 2100 as shown in able(2) (M Nour El-Din, 2013) [5]. Table.2 Summary of assumpions used in developing he waer budge rends waer budge rends Esimaed % change in Nile Flows Drying Scenario -6% -15% -20% -31% Esimaed % change in Nile Flows Weing Scenario +10% +21% +24% +27 Waer Cus due o Upsream Dams (billion m3/yr) hp:// 110 edior@iaeme.com

5 Impac of Climae Change on Resrevior Operaion Policies The Case of Aswan High Dam Reservoir 5. THE MODELING APPROACH GOVERNING EQUATIONS The AHDR is modeled and is operaion is simulaed by a group of governing equaions which describes he waer balance of he reservoir under various consrains concerning sorage volume, ouflow from he reservoir and waer losses as shown in fig.( 3). The waer balance equaion applied on a monhly basis has he following form: dv( ) d nin n ou i 1 dv( ) I d Q in Q, i j 1 Q M ou, j D T S E (1) (2) Where: I : Mean inflow o he sorage in monh (m 3 ). Q : Amoun of waer discharged from he sorage in monh downsream he dam (m 3 ). M : Amoun of waer released from he emergency spillway in he dam in monh (m 3 ). D : The waer demand for Toshka projec (Souh Valley) in monh (m 3 ). T : Amoun of waer released from Toshka spillway in monh (m 3 ). S : Seepage losses from he sorage reservoir in monh (m 3 ). E : Mean evaporaion from he sorage reservoir in monh (m 3 ). E = ((A + A +1 ) / 2) * C *1000 A : Reservoir area a beginning of monh (km 2 ). A +1 : Reservoir area as a he end of monh (km 2 ). C : Evaporaion coefficien peraining o monh (mm). Fig.3 Managemen of he AHDR hp:// 111 edior@iaeme.com

6 Mohamed Ayman El Salawy, Tamer Ali Elgohary, Amir Mohamed Akl Mobasher and Mai Mahmmoud Abd El Aziz The model also includes an equaion which compues he poenial monhly hydropower producion as a funcion of hree facors, (1) he volume of waer discharged, (2) he gross head of his waer, and (3) he efficiency of he couple urbine generaor, which varies he amoun of power produced. The following funcional form represens his relaionship: P = 9.81 * H * Q * C e (3) E = P * K (4) Where: P : Power generaed in monh (kw). E : Energy generaed in monh (kwh). Q : Amoun of waer for energy generaion in monh (m 3 ) H : Average heigh of waer above urbines in monh (m) (reservoir monhly mean waer level - 110) which assumed o be he consan level downsream of AHD (The waer level downsream AHD ranges beween and 113 m above sea levels [5]. C e : Efficiency coefficien of urbines and generaors (0.85). K : Number of hours in monh (24* number of hours in monh ) (hours). 6. SCENARIO ASSESSMENTS The fuure hydrologic scenarios developed have been used o assess he expeced impacs o poenial climae change. In he following discussion, he assessmen resuls are summarized relaive o he following crieria: waer supply releases, reservoir level variaions, Toshka spillway discharges, evaporaion losses and Hydropower producion Sensiiviy of waer supply releases o climae change Under baseline climae scenario, Egyp falls shor of is arge demand in approximaely 31 % of years. This percenage o -6 (+10) % of years for he period I DRY (WET) emissions scenario, and o -15(+21) % of years for he period II DRY (WET). In conras, during period III his percenage significanly o reaches o -20 (+24) % of years for wo global emission scenarios DRY (WET), during period IV his percenage significanly o reaches o -31 (+27) % of years for wo global emission scenarios DRY (WET) as shown in fig.(5). There is a significan probabiliy, he wihdrawal from he AHDR sops during period III and IV DRY for many monhs due o he reservoir levels decreasing as a resul of he serious reducion in he amoun of waer enering he reservoir. The mean annual wihdrawal from he AHDR for he hree periods (period I (2025), period II (2050), and period III (2075)) and wo global emission scenarios DRY (WET) are (61.05), (67.16),44.4 (68.82) and 38.3(70.49) BCM, respecively, compared o he baseline release of 55.5 BCM. Bu according o change in level for AHDR by (-1m) in dry scenarios, here is an increasing in annual releases from he AHDR. Bu for changing in level for AHDR by (+1 m) in we scenarios, here is a decreasing in annual releases from he AHDR. hp:// 112 edior@iaeme.com

7 release from he AHD (BCM) Impac of Climae Change on Resrevior Operaion Policies The Case of Aswan High Dam Reservoir S1-"BASE LINE"-LEVEL175 S1-"2025-DRY"-LEVEL175 S1-"2050-DRY"-LEVEL175 S1-"2075-DRY"-LEVEL175 S1-"2100-DRY"-LEVEL175 S1-"2025-WET"-LEVEL175 S1-"2050-WET"-LEVEL175 S1-"2075-WET"-LEVEL cumulaive frequency (%) Fig.4: frequency curve of annual releases from he AHDR 6.2. Sensiiviy of reservoir level variaions o climae change Table.3 is a summary characerizaion of variaion in he reservoir level, his analysis represens in he waer levels limis and corresponding percenage of occurrence for all climae scenarios. From hese able, i can be concluded ha he waer levels upsream he dam are affeced by he changes in he inflows. The maximum waer levels upsream he AHD of all climae scenarios wihin he waer year did no exceed 182 m, bu some waer levels are below he minimum allowable limis (147 m). Table 3 Level variaions characerisics in he AHDR Period I Period II Period III Period IV Level Baseline DRY DRY DRY DRY (m) % WET% WET% WET% WET% % % % % > > > , > < Sensiiviy of Toshka spillway discharges o climae change Under he baseline climae scenario, annual discharges o Toshka spillway vary beween BCM wih a mean of abou 4.73 BCM and occur in approximaely 41 % of years. The ouflows discharged o Toshka Spillway are influenced by increasing he annual inflow and raising waer level upsream he AHD. For example, discharges o Toshka spillway are negligible in period III and period IV due o reducion of he reservoir waer levels in hose periods. For he period I, he range of projeced discharges o Toshka spillway is 0 (0) o 9.22 (15.36) BCM and occur in approximaely (37.90) % of years for DRY (WET) emissions scenario (fig. 6). The majoriy of scenarios show significan poenial increasing in a moun of he released waer o Toshka spillway for he period I, he range of projeced releases hp:// 113 edior@iaeme.com

8 discharge o oshka spillway (BCM) Mohamed Ayman El Salawy, Tamer Ali Elgohary, Amir Mohamed Akl Mobasher and Mai Mahmmoud Abd El Aziz grows o 0 (0)-9.22 (15.59) BCM. Bu according o change in level for AHDR by (- 1m) in dry scenarios, here is almos none changing in Toshka spillway discharge. Bu for changing in level for AHDR by (+1 m) in we scenarios, here is an increasing in Toshka spillway discharge S1-"BASE LINE"-LEVEL175 S1-"2050-DRY"-LEVEL175 S1-"2100-DRY"-LEVEL175 S1-"2050-WET"-LEVEL175 S1-"2100-WET"-LEVEL175 S1-"2050-DRY"-LEVEL174 S1-"2025-DRY"-LEVEL175 S1-"2075-DRY"-LEVEL175 S1-"2025-WET"-LEVEL175 S1-"2075-WET"-LEVEL175 S1-"2100-WET"-LEVEL cumulaive frequency(%) Figure 5 Frequency curve of annual Toshka spillway discharges from he AHDR Sensiiviy of evaporaion losses o climae change Figure 7 illusraes he frequency disribuion of he annual evaporaion losses, from his figure i can be noiced ha (51.07) and 6.90 (75.86) percen of years during periods I, II had evaporaion losses greaer han 12.5 BCM, compared o he baseline percen of %, while in almos all years during period III and period IV for dry scenario had evaporaion losses less han 12.5 BCM. According o climae change scenarios. The annual evaporaion losses vary beween BCM, wih a mean of abou BCM for he baseline climae scenario. Bu according o change in level for AHDR by (-1m) in dry scenarios, here is a small changing in evaporaion losses. Bu for changing in level for AHDR by (+1 m) in we scenarios, here is an increasing in evaporaion losses. hp:// 114 edior@iaeme.com

9 hydropower producion (GWH) av.evaporaion losses (BCM) Impac of Climae Change on Resrevior Operaion Policies The Case of Aswan High Dam Reservoir cumulaive frequency (%) S1-"BASE LINE"-LEVEL175 S1-"2025-DRY"-LEVEL175 S1-"2050-DRY"-LEVEL175 S1-"2075-DRY"-LEVEL175 S1-"2100-DRY"-LEVEL175 S1-"2025-WET"-LEVEL175 S1-"2050-WET"-LEVEL175 S1-"2075-WET"-LEVEL175 S1-"2100-WET"-LEVEL175 S1-"2100-WET"-LEVEL176 Fig.6: Frequency curve of annual Evaporaion losses from he AHDR Sensiiviy of hydropower producion o climae change There are a few aspecs of he frequency disribuions ha are noable, maximum annual hydropower producion occurs in period I (WET), and exceed GWh in approximaely 6.90% of years. For period III DRY, he hydropower producion sops for hree monhs due o he reservoir levels falling below he minimum level for he hydropower generaion, and he annual hydropower producion is less han 8000 GWh in almos all years (fig. 8). Under he baseline climae scenario, annual hydropower producion a he AHD varies beween GWh, wih a mean of abou 7574 GWh. Bu according o change in level for AHDR by (-1m) in dry scenarios, here is a small changing in hydropower producion. Bu for changing in level for AHDR by (+1 m) in we scenarios, here is a decreasing in hydropower producion S1-"BASE LINE"-LEVEL175 S1-"2025-DRY"-LEVEL175 S1-"2050-DRY"-LEVEL175 S1-"2075-DRY"-LEVEL175 S1-"2100-DRY"-LEVEL175 S1-"2025-WET"-LEVEL175 S1-"2050-WET"-LEVEL175 S1-"2075-WET"-LEVEL cumulaive frequency (%) Figure 7 Frequency curve of annual hydropower producion from he AHDR. hp:// 115 edior@iaeme.com

10 Mohamed Ayman El Salawy, Tamer Ali Elgohary, Amir Mohamed Akl Mobasher and Mai Mahmmoud Abd El Aziz 7. CONCLUSIONS 1. The sudy showed how climae changes affeced he reservoir operaion in case of flood or drough scenarios. 2. For a dryer scenario, irrespecive of he level of inflow reducion, Egyp migh have o face waer shorage. 3. Egyp s average annual wihdrawal from AHDR is expeced o increase due o climae change a WET scenario by 5.55 x 109 m3 (2025), x 109 m3 (2050), x 109 m3 (2075) and x 109 m3(2100). However, Egyp will suffer significan shorfalls relaive o hisorical average releases from AHDR reaches o 3.33 x 109 m3(2025),8.32 x 109 m3 (2050),11.1x 109 m3(2075) and 17.2 x 109 m3 (2100)a DRY scenarios. 4. Hydropower producion a AHD is projeced o increase a WET scenario (2100) o 122 percen of hisorical average producion, bu hen decreasing o 57.7 percen of he hisorical mean for DRY scenario (2100). 5. Changing he level for AHDR by - 1 m for dry scenario, here is a small differen in release, discharge for Toshka spillway, and he hydropower producion. 6. Changing he level for AHDR by + 1 m for we scenario, here is an improved in each of release, discharge for Toshka spillway, and he hydropower producion. 7. Climae impac assessmens on he AHDR operaion have produced meaningful resuls ha can now be incorporaed in waer managemen and policy-making consideraions; 8. RECOMMENDATIONS 1. The Effec of Ehiopian blue Nile projec on AHDR operaion policy mus be sudied. 2. The Effec of AHDR and climae changes scenarios on grea Nubian sandsone aquifer mus be sudied. REFERENCES [1] Minisry of waer resources and irrigaion, (2005), Waer for he fuure, Naional waer resources plan 2017, Cairo, Egyp. [2] Srzepek, K. M.&Yaes, D. N., (2000), Responses and Thresholds of he Egypian Economy o Climae Change Impacs on he Waer Resources of he Nile River, Climaic Change46: [3] Sadek, N. & Aziz, M. (2005), Waer flood managemen of Lake Nasser afer he new Toshka barrages consrucion, Ninh Inernaional Waer Technology Conference, IWTC9, Sharm El-Sheikh, Egyp. [4] Georgakakos, A. P., Yao, H., and Miller, F., (May 1997), A Decision Suppor Sysem for he High Aswan Dam, Waerpower. [5] Mohamed M.Nour El Din, (January 2013), Proposed Climae Change Adapaion Sraegy for he Minisry of Waer Resources & Irrigaion in Egyp, Cairo, Egyp. [6] Manjunaha M.C, Basavarajappa H.T and Jeevan L, Climae Change and Is Impac on Groundwaer Table Flucuaion In Precambrian Terrain of Chiradurga Disric, Karnaaka, India Using Geomaics Applicaion, Inernaional Journal of Civil Engineering and Technology, 6(3), 2015, pp hp:// 116 edior@iaeme.com