Hydrological modeling, impact of land-use and land-cover change on hydrological process and sediment yield; case study in Jedeb and Chemoga watersheds

Abstract

Land use and land cover changes in the Jedeb and Chemoga watersheds have been detected in the past 29 years. The study used ERDAS IMAGINE 2015 tools to classify landsat 5 TM, landsat satellite images for the preparation of the year 1990, 2000, 2009 and 2018 land use class maps through likelihood supervised classification techniques. The SWAT model has been used to determine the seasonal variability of streamflow and sediment yield due to land use and land cover changes in the watersheds. To calibrate and validate streamflow and sediment yields as well as to test SWAT model performance SWAT-CUP SUFI 2 algorithm was used. The outcome showed that 29 years generalized shift of 62.3% increase in farm land, 57.8% decrease in forest cover, 52.4% decrease in grass land, 64.2% decrease in shrub land, 145.2% increase in bare land and 46.5 percent increase in Jedeb watershed settlement. Similarly, the analysis showed that 47.3% increase in farm land, 81.8% decrease in forest cover, 148.9% increase in grass land, 89% decrease in shrub land, 10.7% increase in bare land and 96.9% decrease in Chemoga watershed water body. The average monthly flow of Jedeb watershed flows increased by 39.31 m3 / s from 1990 to 2009 and decreased by 17.19 m3 / s from 2009 to 2018. In Chemoga watershed average monthly streamflow increase between 1990 and 2009 in 36.73 m3 / s but decrease between 2009 and 2018 in 37.77 m3 / s. The average monthly Jedeb watershed sediment yield decreased by 204.59 ton / month from 1990 to 2000, increased by 15,962.76 ton / month from 2000 to 2009 and ultimately decreased by 9,012.83 ton / month from 2009 to 2018. Average monthly sediment rises in Chemoga watershed from 1990 to 2000 at 13,618.72 ton / month, decreased by 11,316.6 ton / month from 2000 to 2009 but increased by 11,192.93 ton / month from 2009 to 2018. The result indicates a strong agreement between observed ad simulated streamflow and sediment yield during calibration and validation, with a minimum result of R2=0.68 and NSE=0.54 and a maximum of R2=0.88 and NSE=0.84. The model performs well in estimating streamflow and sediment yield Jedeb and Chemoga watersheds. Therefore, special attention should be needed for Jedeb watershed for sustainable water resource management.