Dam operation using satellite data and hydrological models: the case of Roseires dam and Grand Ethiopian Renaissance Dam in the Blue Nile River

Figures & data

Figure 1. (a) Main features of the study area: major irrigation schemes, major cities (population > 200,000 people) and large dams; (b) affected water supply utilities in the capital Khartoum; and (c) distance between the Grand Ethiopian Renaissance Dam (GERD) and Roseires.

Note: DCUA, Dam Complex of Upper Atbara; RN, BN, WN, AT, River Nile, Blue Nile, White Nile and Atbara River, respectively.

Figure 2. Analytical framework for computing river inflow into the Roseires reservoir.

Figure 3. Main characteristics of the GERD drawn from different sources given in Table 1.

Figure 4. Middle section during overtopping in 2020 and shortly before overtopping in 2021 showing the height of the middle section.

Sources: https://twitter.com/mowe_ethiopia; https://twitter.com/seleshi_b_a

Table 1. GERD main characteristics.

Item	Characteristics	Description and source
River diversion culverts	4 culverts each = 7.5 × 8.3 m	Used during the early stages of construction. The first two closed at a reservoir level of 540 m. The remaining two closed at 560 m (Pietrangeli et al., 2017)
	Inlet elevation = 500 masl
	Maximum capacity, each = 2700 m^3/s
Middle section	Rectangular weir with a 260 m width	Overtops when inflow exceeds the capacity of the lower gates (culverts, outlets, turbines) (Pietrangeli et al., 2017; Google Earth)
Bottom outlets	2 outlets, each = 5.5 × 4.5 m	Planned to be ready for operation after Stage I of first filling (> 595 m) (Pietrangeli et al., 2017). Used during second and third years of filling (2021 and 2022)
	Inlet elevation = 542.25 masl
	Maximum capacity, each = 886 m^3/s, at 640 m
	Minimum capacity, each = 386 m^3/s, at 565 m
Early generation units (EGUs)	2 units on the right bank, each with a capacity of 375 MW	Minimum operation level is 560 masl (Basheer et al., 2020a)
Normal generation units (NGUs)	5 units on the right bank and 6 units on the left bank each with a capacity 400 MW	Minimum operation level is 595 masl (IPoE, 2013)
Gated spillway	6 sectors gates, inlet invert elevation 624.9 masl, maximum capacity 14,700 m^3/s, with 84 m width	IPoE (2013).

Table 2. Examples of the media sources used to track the progress of the Grand Ethiopian Renaissance Dam (GERD) construction during filling of 2021 and 2022. Several other sources were also consulted.

Information	Sources	Remarks
Dam characteristics and progress of construction	https://www.skyscrapercity.com/threads/nile-river-valley-ethiopia-grand-ethiopian-renaissance-dam-4-8-billion-u-c.1446571/	A forum started in September 2011 for GERD news and construction progress, and milestone achievements
Progress of dam construction	https://www.skyscrapercity.com/threads/nile-river-valley-ethiopia-grand-ethiopian-renaissance-dam-4-8-billion-u-c.1446571/page-130	Page 130 includes examples of photos of dam construction showing design section
Progress of dam construction	https://www.youtube.com/@kingsofabbay	Individual YouTube channel following the progress of the GERD construction
Progress of dam construction	https://twitter.com/RenaissanceDam	Individual Twitter account following the progress of the GERD construction
Information, news and announcements for GERD	https://twitter.com/seleshi_b_a	Official account
Information, news and announcements for GERD	https://twitter.com/mowe_ethiopia	Official account
News, starting generation for GERD	https://www.africanews.com/2022/08/11/ethiopia-announces-that-second-turbine-in-gerd-is-in-operation/	AfricaNews website, 2022: ‘Ethiopia announces that second turbine in GERD is in operation’
News, second filling will be during July–August, 2021	https://ethiopianmonitor.com/2021/04/18/ethiopia-water-flow-will-go-uninterrupted-during-second-filling-of-gerd/	Prime minister announced that the filling of the GERD will be during July–August 2021
Information, news and videos for GERD	https://www.facebook.com/aljazeera/	Aljazeera TV, extracting the photos form media reports
Information news and videos for GERD	https://www.youtube.com/watch?v=VQmTC6UNPvU&list=PLzGHKb8i9vTzLK2JwluwqDsIcyApcBNiZ	An example of one video includes photos and information from 11 August 2022
Information news and videos for GERD	https://www.youtube.com/@EthiopianNewsAgency/videos	ENA TV, extracting photos form media reports

Figure 5. Construction rate diagram of the GERD middle section height, as envisaged on 11 July 2021.

Table 3. Meso-scale hydrological model (mHM) global datasets used for the model (Lorenz et al., 2019).

Product	Dataset name	Developing Institute	Websites
DEM	Global Multi-resolution Terrain Elevation Data (GMTED2010)	US Geological Survey (USGS) and National Geospatial-Intelligence Agency (NGA)	https://topotools.cr.usgs.gov/gmted_viewer/gmted2010_global_grids.php
Soil	SoilGrids	Wageningen University	ftp://ftp.soilgrids.org/data/recent/
Geology	Global Lithological Map (GLiM)	Institute for Biogeochemistry and Marine Chemistry, KlimaCampus, Universität Hamburg	https://doi.pangaea.de/10.1594/PANGAEA.788537
Land cover	Global Land Cover (GlobCover)	European Space Agency (ESA), Université Catholique de Louvain	http://due.esrin.esa.int/files/Globcover2009_V2.3_Global_.zip
Leave area index (LAI)	Global Inventory Modelling and Mapping Studies (GIMMS)	Global Land Cover Facility, University of Maryland	http://iridl.ldeo.columbia.edu/SOURCES/.UMD/.GLCF/.GIMMS/.NDVIg/.global/

Figure 6. Structure of the meso-scale hydrological model (mHM).

Figure 7. Flow chart of the processes of GERD’s water level derivation.

Table 4. Statistical indices for the performance of the meso-scale hydrological model (mHM) model.

Parameter	Equation	Calibration (2002–06)	Validation (2007–11)
KGE	$1-\sqrt{{(\mathit{r}-1)}^2+{(\frac{{\sigma }_y}{{\sigma }_x}-1)}^2+{(\frac{\bar{y}}{\overline{x_i}}-1)}^2}$	0.89	0.90
NSE	$1-\left(\frac{{\sum }_{\mathit{i}=1}^n{(x_i-y_i)}^2}{{\sum }_{\mathit{i}=1}^n{(x_i-\overline{\stackrel{‾}{x}})}^2}\right)$	0.89	0.91
R^2	$\frac{{\sum }_{\mathit{i}=1}^n\left(x_i-\bar{x}\right)\left(y_i-\bar{y}\right)}{\sqrt{{\sum }_{\mathit{i}=1}^n\left(x_i-\bar{x}\right)\left(y_i-\bar{y}\right)}}$	0.92	0.93
PBIAS	$\left(\frac{\sum y_i-\sum x_i}{\sum x_i}\right)\mathrm{x}100$	−0.84%	6.5%

Figure 8. Observed and simulated daily discharges at El–Deim station computed by the meso-scale hydrological model (mHM) derived by CHIRPS dataset: (a) calibration and (b) validation.

Figure 9. GERD level–area–volume relationship derived from DEM.

Figure 10. GERD reservoir level: reference level (actual); Sentinel-1, -2 and Jason-3 (altimetry).

Figure 11. Correlation of the derived reference (actual) water level against Sentinel-1, -2 and Jason-3 (altimetry). The determination coefficient R² and T-test values for statistical significance at a 95% level are shown (critical value = 2.0).

Figure 12. Derived water level from Sentinel-1, -2 and Jason-3 compared with the reference (actual), after correction.

Figure 13. Measured GERD releases before, during and after the overtopping in 2020, 2021 and 2022 compared with the long-term average at El-Deim (Mm³/day).

Figure 14. Predicted date of overtopping the middle section issued on 13 July 2021 (top) and 5 August 2022 (bottom).

Pietrangeli, G., Bezzi, A., Rossini, C., & Masciotta, A. (2017). Design of Grand Ethiopian Renaissance RCC main dam [Paper presentation]. Conference: Africa 2017, Marrakech, Marocco.

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