Mapping Upstream Basin Boundaries for Iowa Communities

Project Personnel (University of Iowa): Dr. Ricardo Mantilla (Assistant Research Engineer),  Radoslaw Goska (Engineer II), Dr. Witold Krajewski (Professor), and Eric Osgood (Undergraduate Student)

An important lesson learned by many communities after the 2008 floods is that the precipitation causing flooding in a community is not always generated locally.  Runoff from heavy rain events in the remote reaches of a basin may cause flooding in communities far downstream from the rain event.  In some cases, these flood events, or the magnitude of these events, are unanticipated by the communities.  With this in mind, the IFC is advancing a project to map the upstream basins of Iowa communities vulnerable to flooding.  An improved knowledge of the upstream basin will allow communities to better monitor these basins and to organize and communicate with their upstream neighbors on watershed management projects.

Example of two river basins outlined for Ames in central Iowa.

The IFC developed tools for delineating river basin boundaries and the corresponding river network for Iowa communities.  This will help community leaders and citizens identify and monitor the upstream regions that are drained by the streams or rivers that run through their community.  This knowledge will also provide the necessary information to design guidelines for watershed management projects to improve water quality and/or to target storm runoff control projects.  The IFC is currently calculating basin boundaries for rivers passing through communities with more than 1,000 inhabitants (approx. 200 thus far).  The rivers are selected based on their potential for flooding.  Basin boundaries are calculated using recently updated digital elevations models of the state.  These maps are posted in the IFC website using a user-friendly web interface (Maps: Where is the water coming from?)