| Continuous water diversions, water operations, and land-use changes in the Delta have affected Delta water flows, quality, and suitability for native fish species. Knowledge and understanding of the flows in Delta rivers, channels, and streams is crucial to solve the Delta's many problems. In an on-going effort to better understand and manage the Delta, a collaborative, integrated approach was used to better predict internal Delta Island Consumptive Use of water (DICU) values and water quality variables on a higher resolution and base diversion and return locations on current high-resolution topography rather than past approximations. The Delta islands known as Fabian Tract and Staten Island were selected for this study based on available data and island accessibility. A combination of historical diversion and return location data, water rights claims, and LIDAR digital elevation model data were used to predict diversion and return locations on the islands. The accuracy of the predicted diversion and return locations was analyzed and improved through ground-truthing. To calculate water requirements and runoff returns from agricultural land-use, incorporating soil and land-use characteristics as well as weather data, the IWFM Demand Calculator (IDC) was selected. The choice was based on model capabilities, ease of use, applicability, and recommendations. As input to the IDC model, Fabian Tract and Staten Island were divided into grid cells forming subregions, representing fields, levees, ditches, and roads.;The subregions were joined to form diversion and return watersheds representing the total area supplied by a given water source or the total drainage area for a given return. Diversion and return volumes were limited to physical abilities of the systems. Model results provide daily estimates of the volume of water diverted and returned from actual diversion and return locations, providing insights into daily agricultural diversion and return operations within the Delta that are missed in DICU models and supporting sustainable solutions for the problems of the Delta. |
