A GIS-based model to estimate the regionally distributed drought water demand

A GIS-based Water Resources and Agricultural Permitting and Planning System (GWRAPPS) was developed by integrating the Agricultural Field Scale Irrigation Requirements Simulation (AFSIRS) crop water model, a geographic information system (GIS) and a database management system within an ArcGIS framework. GWRAPPS facilitates the quantification of irrigation water for regional planning and farm scale permitting purposes under statistically average to drought conditions using spatially distributed soils, land-use, and long-term daily climate data. In addition, the system provides regional estimates of daily water withdrawals that are necessary for input into conjunctive surface/groundwater models. This paper presents two Florida case studies that demonstrate GWRAPPS’ ability to characterize irrigation needs based on spatially heterogeneous soil and climate data in contrast to a spatially lumped model. The results show that while inclusion of soil heterogeneity is important to capture water requirements at individual farms, regional water demands are adequately captured using each farm’s predominant soil.