FRIEND/Nile First Phase
Within the framework of the Flanders-UNESCO Science Fund-In-Trust (FUST) cooperation, the Flemish Government of Belgium supported the FRIEND/Nile project. They supported the first phase of the project with an amount of US$ 929,700 for the period from 2001 to 2006. The project has been officially launched in November 2001.
During the first phase of the FRIEND/Nile project, a network of water resources experts in the Nile basin and the Flemish community has been established. Four research teams have been defined comprising researchers from the participating Nile Countries and Flemish experts. The technical themes of FRIEND/Nile Project are:
- Rainfall-Runoff Modeling (RRM), coordinated by the University of Dar Es Salaam of Tanzania
- Sediment Transport and Watershed Management (STWM), coordinated by the UNESCO-Chair in Water Resources of Sudan
- Drought and Low Flow Analysis (DLFA), coordinated by the University of Nairobi of Kenya
- Flood Frequency Analysis (FFA), coordinated by the Water Resources Research Institute of Egypt
A summary of the research outputs of each research component during the period 2001-2006 is presented below as follows:
a. Rainfall-Runoff Modeling (RMM) Component
Single storm events in the Wadis were modeled by WMS and HMS within the three selected basins which are:
- Wadi-al Arbain
- Wadi Gudierat
- Wadi Sudr in Sinai - Egypt
Many parameter estimations and objective functions were tried for hydrograph calculations. Modeling the river flows of the Awash catchment in the Ethiopian Plateau by using naturalized and regulated river flows was also modeled. The HEC-HMS model and GFFS software were applied for the Nzoia River. They were also applied for other selected basins in the North-Eastern side of Lake Victoria, and the results were obtained. The SWAT model was applied and calibrated in Simiyu catchment in the South-Eastern side of Lake Victoria. It was applied with the required data, and good results were obtained. The data of Blue Nile and the Eddeim catchments was identified and used for the applications of the HMS, WMS, and GFFS models. Good results were obtained and presented. Table (1) reported catchment characteristics of the researched catchments.
Table (1) Catchment characteristics of the researched catchments
|Egypt||Sinai||Mountainous||Not defined||Semi Desert|
|Kenya||Nzoia, Nyando||Hilly & Mild||Grass/Woodland, Cultivated||Wet/Dry|
|Sudan||Eddeim||Not defined||Not defined||Wet/Dry|
The RRM research team in all participating countries has jointly prepared the following technical papers:
- Application of the Soil Water Assessment Tool (SWAT) in Simiyu River catchment
- Appraisal study to select suitable Rainfall-Runoff model(s) for the Nile River Basin
- Watershed Modeling of Wadi Sudr and Wadi Al-Arbain in Sinai, Egypt
- Rainfall-Runoff Modeling in Selected Catchments in the Lake Victoria Basins
- Challenges of Modeling the Flows of the Nile River
- SMA Based Continuous Hydrologic Simulation Of The Blue Nile
- Rainfall Runoff Modeling in Upper-Awash Sub-Basin
- Long Term Hydrologic Modeling for Simiyu Watershed, Tanzania using Hydrologic Simulation Program-Fortran (HSPF)
The papers were presented in the final conference of the FRIEND/Nile project.
b. Sediment Transport and Watershed Management (STWM) Component
The SMS simulation of the long reach of Awash River does not result in good outputs. This is because there is a limitation of RMA2 in steep slope condition. Hence, the hydrodynamic modeling for a segment of the reach was done to improve the velocity magnitude, water depth, and water surface elevation outputs.
In the case of Sondu basin, the river channel is long with a lot of meanderings and waterfalls. Hence, it did give a lot of complication during the calibration of the SMS. After some serious consultation, it was realized that the SMS works better in river channels that do not have steep waterfalls. Therefore, Sondu basin had to be divided into portions of about 5km stretches for ease of handling and to produce good results.
The two modules of the SMS model namely hydrodynamic (RMA2) and sediment module (SED2D) have been applied to the Simiyu catchment. The obtained results were reasonable but another independent station had to be used to check the accuracy of the simulation. To run SMS-RMA2, it was required to use downstream water level above the highest bathymetry. This is only correct in flood plains and thus not applicable to hilly areas such as the Simiayu River. SMS has also been applied on the selected study reach of the Blue Nile. During the study, the problems facing SMS modeling application were addressed. The collected information included the sediment to generate flow profiles, river morphology, and expected changes regarding sediment concentration through using SMS model. The SMS and capacity building for the technical staff in SMS model application were also mastered.
The SMS was also applied on TOSHKA and AHDR (Aswan High Dam Reservoir). This was to study the effect of sediment on current and future backwater curve and to study the stability of data deposits. The available data for SMS are:
- Banks and bed elevations in X,Y,Z coordinate
- Water surface elevations
- Flow rate (discharge)
- Channel and floodplain characteristic
- Wind Velocity
- Water temperature
For future work, runs of SMS model for the small regions of 20 km length were recommended for:
- Estimation of bed profile of these regions
- Estimation of Water surface profile and velocity distribution in 2-D
- Future prediction of the sediment deposition in Aswan High Dam Lake
Papers were prepared based on the implemented research activities of the STWM component in the participating countries. The participating countries are:
The following papers were jointly prepared and presented in the FRIENSD/Nile Final conference in Sharm ElShiekkh, Egypt:
- Modeling Water and Sediment Fluxes in Steep River Channels: Case of Awash Basin
- Comparison of Two Different Transport Models to Predict Sediment Transport: Simiyu River, Tanzania
- Nile River Sediment Modelling: Challenges and Opportunities
- Modeling of Sedimentation Process in Aswan High Dam Reservoir
- Overview of Sediment Problems in Nile Basin
- Effect of Upstream Structures on Delta Deposit Progress in Aswan High Dam Reservoir
- An Overview of Soil Erosion Around Lake Victoria
- Limitations of Hydro-dynamical Models with Limited Data Available Case Study: Sondu River Basin (Kenya)
c. Drought and Low Flow Analysis (DLFA) Component
The POT method was used to analyze all the available data on river discharges or surface water levels. It was done on the appropriate time-scale relevant to the country. A drought index for drought analysis was developed and the drought results were regionalized. The Q-Q plot of the ECQ software was used in all the country applications.
Ten-day average flow discharge covering 24 to 40 years of at least 3 stations in the catchment of River Sobat was used in the analysis. The discharge had a monthly flow covering 130 years of a station on the main steam of the River Nile. Annual rainfall data covering 28 to 30 years of about 3 stations in the catchment of river Sobat was also used. Daily flow discharge with monthly rainfall and evaporation in the Blue Nile and River Atbara catchments were used in the analysis. Also, daily rainfall data covering about 30 years of about 150 stations in the catchment of the Lake Victoria was used in the analysis. Daily flow discharge and daily rainfall data in the catchments of Lake Victoria located were used in this analysis.
The DLFA research team has jointly prepared the following papers.
- Analysis of Annual Droughts in Kenya Using an Objective Annual Rainfall Drought Index (This paper was submitted to an international journal for publication)
- Low Flow Frequency Analysis Based on Flow Filtering and Independent Period Selection for Some Selected Catchments in the Lake Victoria Basin
- QDF Relationships for Low Flow Return Period Prediction
- Statistical Analysis of Dry Periods in Seasonal Rivers
- Analysis of the Return Periods of Low Flow Hazards in Egypt and Sudan
For each paper, there was a coordinator from the DLFA team members who was responsible to compile the contributions of the other researchers.
d. Flood Frequency Analysis (FFA) Component
The harmonized methodology of the regional flood frequency analysis has been conducted at different locations within the Nile basin. Based on the analysis of Q-Q plots, a normal tail is found for the most of the rivers. Therefore, the selected distributions are evaluated in the exponential Q-Q plot for EV1/Gumbel using MOM, Ml, and PWM. Other distributions are evaluated in Pareto. The whole range of observations does not follow one FF distribution at some sites. This might be explained by flooding influence along the river. Therefore, it is suggested to calibrate a separate distribution for two sub-populations. One is for the non-flood part, while the other is for the flood part. A comparison of the calibration results has been carried out for the distribution parameters (for EV1/Gumbel and for GEV, and according to different parameter estimation methods).
A regionally calibrated relation between the Mean Annual Flood (MAF) and the catchment characteristics was established using multiple linear regressions. The catchment characteristics are:
- Average slope
- Average annual rainfall
This relation, together with the developed regional frequency curves could be used to estimate flood magnitudes. This is done with various return periods for un-gauged catchments at any homogeneous region with the regions under consideration. Most countries did not achieve the final results and they recommended follow up training on GIS tool. The tool can be used to extract catchment physiographic characteristics such as land cover, slope and elevation. These characteristics can be used to improve the regionalization analysis.
The following technical papers were jointly prepared by the FFA research team:
- At Site Flood Frequency Analysis for The Nile Equatorial Basins
- Comparison between Annual Maximum and Peaks over Threshold Models For Flood Frequency Prediction
- Regional Flood Frequency Analysis in the Nile Basin
- Highlights on the Flooding Influence in the Flood Frequency Analysis In The Nile Basin
- Homogeneity Testing For Peak Flow in Catchments in the Equatorial Nile Basins
- Flood Frequency Analysis of the Eastern Nile Rivers
- At-Site and Regional Flood Frequency Analysis of the Upper Awash Sub – Basin in the Ethiopian Plateau