HYDROLOGIC RESPONSE MODELLING IN LUTANANDWA RIVER CATCHMENT, LIMPOPO, SOUTH AFRICA, USING SOIL WATER ASSESSMENT TOOL (SWAT) MODEL

Abstract

Flow simulation is important in planning and design of engineering hydraulic structures. The purpose of this study is to predict flow in the Lutanandwa river catchment in the Luvuvhu river basin, Limpopo, South Africa. The input data needed for SWAT model set up included Digital Elevation Model (DEM), hydro meteorological data, land cover and soils data acquired from various institutions in South Africa. The DEM was processed from contours in the Department of Hydrology and Water Resources, University of Venda. Meteorological data was acquired from the South African Weather Service (SAWS). Observed daily stream flow data was obtained from the Department of Water Affairs and Sanitation. Land cover data was acquired from processed satellite imagery obtained from the department of Environmental Affairs and ground truthing carried out to verify the land cover information. Soils information was obtained from the Agricultural Research Council – Institute of Soil, Climate, and Water (ARC-ISCW). The soils data was obtained in the form of geo referenced land type map. Based on assessment of the data status, the period 2002 to 2014 was selected for modeling. The meteorological data processed for this period was prepared in the appropriate format for model set up. Soil water characteristic calculator was used to estimate the soil properties required as input to SWAT model. The land cover types in the study area was converted to corresponding SWAT land use types. The statistical parameters required as input to the weather generator in the SWAT model was calculated using the pcpSTAT programme which was used to compute the parameters using weather information. All input data was processed and prepared in the appropriate format for model set up. The processed input data was loaded into the Geographic Information Systems (GIS) interface of the SWAT model to enable model set up for flow simulation.