Abstract:
This research work concentrated on using Geographic Information Systems (GIS)
techniques to produce digital-hydrological maps and to formulate a useful tool for
rainfall-runoff estimation.
Produced maps were based on elevation data provided by Shuttle Radar
Topography Mission, SRTM. Use of such maps enables proper planning of various
water-harvesting projects and integrated water resources management in the area.
Hydrological mapping was done through several sub-software models. Analysis of
produced maps emphasized the use of Digital Elevation Models, DEMs. DEMs
generate adequate and better quality maps than manual interpretation from direct
satellite imagery.
Visual BASIC for Applications (VBA) programming language techniques were
used in this work to formulate a computer model to be run under ArcMap software
environment. Formulated Curve Number-Runoff Estimation Model (CN-REM) was
formulated and tested to read input data in the form of digital maps (soil types, land
uses and rainfall) for any study area. This procedure allows determination of the
Curve Number (CN) for each polygon according to the Soil Conservation Service
(SCS) method. Testing, operation and verification of model was done on large and
small scale levels for Greater Darfur area (in western Sudan), and Abu Hamra area
(in Darfur) respectively. Estimated values of volumetric water discharge in Wadi
Abu Hamra were related to results obtained by Abu Hamra Water Harvesting Project
Team (AHWHPT) using the modified rational method. The discrepancy between the two
methods emphasizes the need for CN-REM model calibration against measured results for
any region before using the software for runoff estimation
Analysis of produced maps emphasized the use of formulated CN-REM rather than
relying on laborious manual processes. Time loss was dramatically reduced and
resultant maps were highly adequate.
