WIT Press

Rainfall-runoff Model Using The SCS-CN Method And Geographic Information Systems: A Case Study Of Gomal River Watershed


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159 - 170




1339 kb

Paper DOI



WIT Press


M. Kh. Askar


s This research aims to determine the runoff depth using the Soil Conservation Service Curve Number (SCS-CN) method with Geographic Information Technique (GIS). A rainfall-runoff model is a mathematical model describing the rainfall-runoff relations of a catchment area, drainage basin or watershed. Remote sensing technology can augment the conventional methods to a great extent in rainfall-runoff studies. The role of remote sensing in runoff calculation is generally to provide a source of input data or as an aid for estimating equation coefficients and model parameters. The study was carried out in the Gomal River watershed about 540 km2 catchment areas, Latitude: 36.5155556°, Longitude: 43.5144444°. The area within the boundary of the Kurdistan region starts from north of Shahia to south west of Dohuk City. A SCS-CN method was applied for estimating the runoff depth in the semi-arid Gomal watershed. Hydrologic stream flow, soil group, slopes and land use maps were generated in a GIS environment. The curve number method was used to estimate the runoff depth for selected storm events in the watershed. Effect of slope on CN values and runoff depth was determined by using the WMS 7.1 program. The max rainfall depth with different return period was calculated and the mean annual rainfall depth for the year 1947 to 2005 of Mosul metrological station was used to calculate the runoff depth of the catchment area. The results of the WMS 7.1 program showed that the CN curve number for the area is about 80. The average annual runoff depth is equal to 311.14 mm Keywords: remote sensing, geographical information systems, watershed, SCSCN rainfall-runoff modelling, WMS 7.1 program.


remote sensing, geographical information systems, watershed, SCSCNrainfall-runoff modelling, WMS 7.1 program