Agriculture drought assessment using simulated soil moisture in Ruvu river basin

This research endeavored to assess agriculture drought using simulated soil moisture of Ruvu River Basin. Remote sensing data (Landsat images) of 1991 and 2000 and DEM of 90mx90m resolution were used. ILWIS and ArcView GIS software were used to process the remote sensing data. The Soil and Water Assessment Tool (SWAT) was used to simulate the long term hydrology of the basin. Flow and climatic data were collected and processed. The hydrologic model was calibrated for streamflow using an auto-calibration algorithm and validated over multiple years. The overall R2 for the calibration period was 0.42 and the validation period was 0.38. Overall, the model was calibrated, and the simulated streamflow compared well with the observed streamflow under varying land use scenarios, hydrologic and climatic conditions. Simulated soil moisture was analyzed using NDVI data. Analysis showed that the simulated soil moisture was well-correlated with NDVI. In the current study the drought index was compared with crop yield data. However, if crop yield data from individual farms is available, it could be used to develop a yield forecast model based on current drought conditions. Frequency and spatial characteristics of drought could be studied to develop an intensity-area-duration curve to characterize the spatial patterns of drought. This will help identify areas frequently affected by droughts and its spatial extent, which could be used for the development of a drought preparedness plan.