ANALYSIS OF LAND USE / LAND COVER AND CLIMATE IMPACTS ON KANGIMI STREAMFLOW AND SEDIMENT YIELD: KANGIMI CATCHMENT, KADUNA NIGERIA

Abstract

The Kangimi reservoir is an important dam augmenting water supply and recreational activities in and around the Kangimi Watershed in Kaduna, Nigeria. However, the impending hydrological effect of land use / land cover (LULC) dynamics in relation to agricultural expansion has not been established. This study determines the LULC dynamics on hydrological parameters (streamflow and sediment yield) using the ArcGIS 10.2 interfaced with ArcSWAT 2009 and detailed LULC maps (1975, 2000 and 2013). The catchment was delineated into ten subbasins, and 39 hydrological response units (HRUs) were created according to multiple HRU development. Kangimi hydrology was simulated for three different LULC types. The model was verified through calibration and validation to determine its performance; the values were determined to be (R2=0.92, NS=0.93) for calibration and (R2=0.82, NS=0.86) for validation, respectively. The hydrological response was considered based on three conditions (climate of 1979-2014 & 1975 LULC, the climate of 1979-2014 & 2000 LULC, and climate of 1979-2014 & 2013 LULC). Model results for the Kangimi catchment confirm that agricultural growth and bare surface increase led to an increase in annual streamflow and sediment yield. Thehydrology streamflow increased 28.23% (from 345.2 m3/s to 387.37 m3/s) as well as 33.31% (from 60.03 to 90.02 t/ha) of sediment yield due to LULC and climate dynamics. The results confirm the prominence of incorporating physical hydrologic models through the use of GIS for estimating catchment characteristics and the relative effect of LULC dynamics on hydrologic response. A well-parameterized model can be equally used to estimate the impact of LULC dynamics on water quality, pesticide loading, nutrients and land management practice.Keywords: Hydrological parameters, Climate changes, SWAT, GIS