nan Fayyaz-ul-Hassan

Soil and Water Assessment Tool (SWAT) for Rainfed Wheat Water Productivity

Wheat is sown over a wide range of sowing date in various cropping systems of rainfed and irrigated areas of Pakistan. This variation in sowing time is caused by various factors such as erratic rainfall in rainfed area, late planting or harvesting of preceding crop, lack or unavailability of farm machinery and inputs. At present the greatest challenge which is being faced by the agriculture sector is production of more food from less available water. Increasing water productivity of the crops can help in facing this challenge. For understanding the relationship between water and food, a sound knowledge of crop water productivity (CWP) is important. Dynamics of crop environment proved most important in rainfed areas for crop production. Therefore, to achieve higher CWP (crop water productivity) under changing climatic conditions, increasing WUE (water use efficiency) could be an option by adopting mitigation strategies. These measures might be, adopting good management practices like optimizing the sowing date on long-term basis using simulation modeling as decision support tool. In the present study, Soil and Water Assessment Tool (SWAT) model was parameterized and validated to study the relationship between yield and crop water productivity of rainfed wheat. For this study, field experiment was conducted at three locations using three wheat cultivars and two sowing dates. Crop water productivity was calculated by dividing the grain yield by evapotranspiration during crop growth cycle. Satellite based parameterization of study area for GIS mapping, topographic analysis, vegetation dynamics, land use, and soil mapping was done by using different software packages like ArcGIS 10.1, Erdas Imagine, QGIS, and Swat-CUP. The SWAT model was used to simulate the processes related to the soil-crop-atmosphere interaction in the present study and it showed significant potential to simulate CWP.