Nile and GERD Conference Advances in Water Resources Assessment and Optimal Management of Multipurpose Cascade Reservoirs in the Nile River Basin Getachew Tegegne (Ph.D.) Hydraulic, Hydrologic and Water Resources Engineering Assefa M. Melesse (Ph.D.) Professor of Water Resources Engineering Florida International University Contents 1. The Nile River Basin 2. Statement of the problem - Motivation 3. Water resources assessment from both the gauged and ungauged basins 4. Water resources management under emerging scenarios 5. Water resources planning and development 1. The Nile River Basin ü The Nile River Basin includes portions of 11 countries: Ethiopia, Eritrea, Burundi, Democratic Republic of Congo, Kenya, Rwanda, Tanzania, Uganda, South Sudan, Sudan, and Egypt. ü Area coverage: 3.18 × 106 km2 ü The average monthly flow of the White Nile ranging from 580 to 1,270 m3/s at Malakal in South Sudan. 15% of the annual Nile discharge. Fairly stable flow throughout the year ü The average monthly flow of the Blue Nile ranging from 150 to 5,600 m3/s at the Soba gauging station in Khartoum. 85% of the annual Nile discharge. Highly seasonal. Water resources development in the Nile River Basin ü The Low Aswan Dam (1902) in Egypt across the main Nile ü The Sennar Dam (1925) and JeBel Aulia Dam (1937) in Sudan across the Blue Nile and White Nile, respectively. ü A 1959 agreement Between Egypt and Sudan initiated the construction of the Roseries Dam (1966) and Khashm El GirBa Dam (1964) in Sudan. ü The High Aswan Dam (1970) in Egypt. ü Sudan’s modern expansion: The Merowe Dam (2009), the Upper AtBara and Setit Dam complex (2016), and the heightening of the Roseries Dam (2013). ü Ethiopia’s major project: The Finchaa (1973, expanded in 2012), TekeZe Dam (2009), and the Tana-Beles hydropower project (2010). Motivation: why is the water demand growing in the Nile basin? ü This is due to climate change and population growth Temperature evaporation water scarcity o The climate projection over Ethiopia showed that the wet (dry) spells are projected to significantly decrease (increase). o However, the climate projection also showed the increase in extreme precipitation amount above the 95th percentile, which may cause floods in Sudan and Egypt. Nile Basin needs more water infrastructures!!! 2. Statement of the problem Insufficient Lack of Poor water use Lack of sufficient knowledge on cooperation for efficiencies in water storage the hydrology of mutually beneficial agriculture the Nile system mechanisms Climate change - I Climate change - II Impact Temperature increases 15% increase in flow Increasing the risk evaporation increases amount – 50% increase in of flooding and water scarcity flow variability droughts Problem Solution How much? The inter-annual flow 55% additional storage Implement variability reduces capacity to achieve additional storage reliability of existing levels of reservoir maintaining flows reliability 1. The Nile River Basin § The water resources development in Ethiopia would likely to provide a wide-range of benefits for Sudan and Egypt. For example, the Grand Ethiopian Renaissance Dam (GERD) is likely to provide: Sediment Flood reductions management Sudan Hydropower Agricultural uplift development Sediment Less water reductions evaporation Egypt Flood Increases reliability management of water availability Sustainable water resources management of the Nile river Establish Nile Basin wide cooperative framework agreement The water resources assessment and management approach need to be reviewed and updated on a regular basis Assess the outcomes for various users in the region under a range of different development, allocation, and hydrological scenarios The multi-objective evolutionary and/or direct policy search algorithms need to be considered to search solutions along the Pareto frontier with an aim to satisfy various actors in the region 3. Water resources assessment from both the gauged and ungauged basins Fold-I Fold-II Fold-III Fold-IV 3.1 Hydrologic model parameterization in the gauged basins 2001 2001 2001 2001 2002 2002 2002 2002 2003 2003 2003 2003 k-fold cross-validation: k = 4 folds, 2004 2004 2004 2004 9 yrs = calibration and 3 yrs = validation 2005 2005 2005 2005 2006 2006 2006 2006 2007 2007 2007 2007 Assessment Time-domain Quantile-domain 2008 2008 2008 2008 2009 2009 2009 2009 Hydrology Real-time operation Climate Change 2010 2010 2010 2010 2011 2011 2011 2011 Simulation Process wise Water Balance 2012 2012 2012 2012 Legend Water System Management Planning Calibration Validation 400 350 350 High Moist Mid-range Dry Low 300 Flow 300 250 250 200 200 150 150 100 Flow (m^3/s) Flow 100 50 50 0 0 1/1/1995 9/27/1997 6/23/2000 3/20/2003 12/14/2005 0 10 20 30 40 50 60 70 80 90 100 Date % Exceeded or Equalled Automation of Integrated hydro- climatological models GCM 1 GCM 2 GCM 3 GCM n Standardized R Data Format Downscaling Downscaling Model 1 Model n Standardized R Data Format Hydrologic Hydrologic Model 1 Model n Frequency Analysis Artificial neural network 3.2 Water resources assessment in the ungauged basins Ø Ungauged hydrology § Arithmetic mean § Physical similarity § Spatial proximity § Catchment runoff response similarity Ø Catchment runoff response similarity (CRRS) 4. Water resources management: multi-objective reservoir operation Ø Mathematical formulation of a multi-objective reservoir operation a. Objective functions b. Constraints § Minimize the total squared § Storage continuity " = " + , − ,- + - + 5 + 6 deviations (TSD) for irrigation & )3( &) &) &) &) &) &) ∀) = (, *, … , (* , and ∀& = (, *, … annually § Storage limits "&:;& ≤ "&) ≤ "&:=> & (* " ≤ " ≤ " * &:;& & )3( &:=> !"# = % % #&) − ,-&) ∀) = (, *, … , (* , and ∀& = (, *, … &'( )'( § Maximum power production limit § Maximize annual hydropower 0(-&).&)) ≤ ./&:=> production (HP) § Irrigation demands ? ≤ ,- ≤ # & (* &) &) § Downstream requirement ./ = % % 0(- . ) &) &) #-&) ≥ A#-&) &'( )'( § Spill ? ≤ 6&) Example: Reservoir operation with simple approach Three stage reservoir refilling approach a. Objective function: Minimization problem 2 é 2 2 2 ù é T ù æ R - D ö æ R - D ö æ R - D ö êæ S9 - S ö ú f R, S = wêç 1 1 ÷ + ç 2 2 ÷ + + ç 12 12 ÷ ú + 1-w ç 9 ÷ ( ) ç ÷ ç ÷ ! ç ÷ ( )êç ÷ ú êè D1 ø è D2 ø è D12 ø ú ST ë û ëêè 9 ø ûú b. The Lagrangian function of the formulated reservoir operation problem 2 é 2 2 2 ù é T ù æ R - D ö æ R - D ö æ R - D ö êæ S9 - S ö ú L = wêç 1 1 ÷ + ç 2 2 ÷ + + ç 12 12 ÷ ú + 1-w ç 9 ÷ + ç ÷ ç ÷ ! ç ÷ ( )êç ÷ ú êè D1 ø è D2 ø è D12 ø ú ST ë û ëêè 9 ø ûú l1(A12 - R1 - R2 - R3 - R4 - R5 - R6 - R7 - R8 - R9 - R10 - R11 - R12 ) c. The Karush-Khun-Tucker (KKT) conditions æ ö ç ÷ ¶L 2wR1 2w ¶L 2wR2 2w ¶L 2wR12 2w ¶L 2S9 2 = 0 = - - l = 0 = - - l = 0 = - - l = 0 = (1-w)ç - ÷ - l1 2 1 2 1 2 1 ¶S 2 T ¶R1 D D1 ¶R2 D D2 ¶R12 D D12 9 ç S T S ÷ 1 2 12 è 9 9 ø Reservoir operation rules 6 years during extended drought period Actual Dam Level Water Supply for > Attention Municipal + Agriculture + Instream > Caution M&I + Agriculture > Concern M&I > Fatal Partial M&I Demand = Agricultural supply + Municipal supply + Environmental supply 5. Water resources planning and development in the Nile region ü Planning of new water infrastructures in the Nile basin should be carefully evaluated with ROBUST and ADAPTIVE decision making perspectives. ü Robust: an alternative performs satisfactorily over a wide range of scenarios ü Adaptive: reduction of risk over time (flexibility) Real Option Analysis (ROA) Discounted cash flow? ü ROA spread risks over time using options o which is consistent with the adaptive perspective. ü ROA can also consider uncertainty in a modelling framework o which is consistent with the robust perspective. Planning Period: 30 years No of Nodes: (4*3)12 ü Decision node: 4 options Invest, delay, stop, and maintain ü Chance node: 3 Scenarios Normal, moderate drought, and severe drought Proposed adaptation plans for Egypt due to further upstream development Improve the Improve the Avoid high Seawater efficiency of Rain-water Groundwater operation of water desalination water harvesting exploration the existing consumptive project distribution mechanisms reservoirs crops canals Getachew Tegegne (Ph.D.) [email protected] [email protected] Thank You! Without water, the earth would look like the moon.