Grand Ethiopian Renaissance Dam Reservoir Operation Simulation using HEC-ResSim and its impact on downstream Hydropower Generation
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Date
2014-03
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Addis Ababa University
Abstract
In this study, HEC-ResSim model was used to simulate operation of existing hydraulic
infrastructure, and major irrigation schemes in the Eastern Nile river basin and the new hydraulic
infrastructure (GERDP).The main objective of this research is to find out the extents of the
impact to which the introduction of new upstream reservoir, GERDP, on downstream users of
the Nile waters by using the HEC-ResSim reservoir simulation model. Repeated runs of the
HEC-ResSim model were made using different filling and after filling of GERDP scenarios to
compare the effect of GERDP under alternative operating policies.
The computational algorithm in HEC-ResSim is divided in to three major components: (1)
watershed setup, (2) reservoir network, and (3) simulation for Calibration, Baseline and
Alternative (Dry, Wet and Average filling and after filling) phase scenarios. The methodology
computes the required releases to limit storage to the capacity available based on the
probabilistic properties of future flows, conditional to current stream flow conditions.
The first setup was to simulate gaged flow routing without taking into account effects of
development using the flow data of 1956 to 2003 and a good agreement was observed between
simulated and gaged data at El-Deim, Khartoum, Dongola, Hassanab and Tamaniat stations. The
correlation coefficient R2 values for those stations were found to be in good agreement and found
to be more than 0.925 for each station. Following this, the model was configured to simulate the
existing and proposed development intervention.
The baseline development Scenario is considering only existing major water infrastructures (i.e.
reservoirs) and major irrigation schemes in Sudan and Egypt for a period of 1956 to 2003. The
simulation result showed that an average annual energy of 14,810.83GWh/year is produced by
Roseires, Sennar, Merowe and HAD.
The Alternative scenario development which includes during filling and after filling of GERDP,
HEC-ResSim simulation, has discovered that long term effects of new upstream reservoir on the
operation of downstream reservoirs. After filling of GERDP phase scenario simulation using
flow data of 1956 to 2003, the simulation result showed that an average annual energy of
31,363.63GWh/year will be produced by GERD, Roseries, Sennar, Merowe, and HAD (111.76%
increase than without GERD), the reduction of average annual energy by 395.41 GWh/year from
HAD will be compensated by the energy produced by GERDP and Sudan power plants, which
will increase the total energy produced by the whole Eastern Nile system. During the filling phase scenario simulation results showed that an average annual energy of 27,041.96 GWh/year,
25,695.48 GWh/year, and 31,213.61 GWh/year will be produced by the 5 power plants during
Average, Dry and Wet filling Scenarios respectively and average annual energy production from
GERDP will be 11,314.38, 8,974.19, and 11,925.61GWh/year for the respective sequence of
filling years. An average monthly power of 1,625.46MW and average annual energy of
14,238.99GWh/year will be produced during normal operation of GERDP (i.e. after filling from
2019-2066 for 48 years).
Due to upstream regulation (i.e. intervention of GERDP, in the upstream of the Eastern Nile river
basin) there will be an increase in average monthly inflow downstream in the driest month of the
year and the annual average reservoir pool level increase which result in increase of power head.