Development of the Big Sioux River Flood Information System

RESPEC is currently contracted with the SD DENR to develop a flood information system for the entire Big Sioux River Basin. The Big Sioux River Basin has historically experienced repeated flooding. A major flood in the lower basin in 2014 revealed the lack of understanding of how this area behaves hydrologically during flood events. Improving available data was deemed essential to enable state and local authorities to prepare for imminent flood events.

This project involves a hydrologic and hydraulic study that will provide state and local entities with information necessary to better prepare for future flood events. The data and model generated from this study will allow flood managers to predict the impacted areas for a range of flood scenarios. This will allow state and local entities to implement appropriate protection strategies in advance of flood waters. The Big Sioux River flood decision support system will be patterned after a similar system maintained by the Iowa Flood Center (IFC). The Big Sioux Flood Information System (FIS) will be a one-stop web-platform to access community-based flood conditions, forecasts, visualizations, inundation maps, and applications. Real-time and historical water levels, discharge data, and rainfall conditions will be available in the interface by streaming data from automated bridge sensors, USGS stream gauges, NEXRAD radars, and NWS forecasts. The system will include a rainfall-runoff forecast model to provide a flood risk estimate at critical locations throughout the basin to supplement and support NWS forecasts. The system will also provide the user with a relative understanding of the current and forecasted conditions in relation to flood response action levels specific to the location. It will also allow select users to run scenarios such as raising or breeching levees, to assess impacts of flood management strategies.