The Iowa Watershed Approach

The Iowa Flood Center's leadership and technical expertise have helped bring over $100 million to the state of Iowa for the Iowa Watershed Approach—a community-led program supported by state and federal partners to develop and implement strategies to mitigate flood damage and increase resilience. 

Background

In 2010, Iowa received $84.1 million from the U.S. Department of Housing and Urban Development (HUD) to support ongoing disaster recovery programs following the 2008 floods. Of that allocation, $10 million was for watershed demonstration projects to reduce flooding and for educational programming. The IFC received $8.8 million to lead a pilot program called the Iowa Watersheds Project (IWP), which was designed to evaluate and implement flood mitigation practices in five select Iowa watersheds; $800,000 was used to establish the first watershed management authorities (WMA) in Iowa.

As the Iowa Watersheds Project was concluding in 2016, HUD and the Rockefeller Foundation announced $1 billion in available funding through the National Disaster Resilience Competition (NDRC); a Community Development Block Grant program motivated by the aftermath of Hurricane Sandy. The competition focused on helping communities and vulnerable populations recover from previous disasters while also improving their resiliency to future extreme events. States that had received a Presidential Disaster Declaration because of a major natural disaster between 2011-2013 were eligible to compete in the NDRC.

Leveraging the experiences and successes of the Iowa Watersheds Project, the Iowa Flood Center led the successful NDRC proposal development on behalf of the state of Iowa. In January 2016, Iowa received the fourth largest NDRC grant award of $96,887,177 for its proposal titled, “The Iowa Watershed Approach for Urban and Rural Resilience.” The IWA was funded for its holistic approach to the reduction of flooding, the improvement of water quality, and the development of equitable strategies to increase community resilience to water resource challenges. Based on the Iowa Watersheds Project framework, the IWA brought together local, state, and federal partners, empowering them with science-based information to develop long-term watershed management plans and to guide strategic conservation practice implementation efforts that work progressively with agriculture. The program ended in December 2022. 

Technical Resources

In phase one of the IWP, the Iowa Flood Center completed hydrologic assessments and built hydrologic models using the Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) for each watershed. These included detailed information to understand the movement of water within the watershed, identify areas with high runoff potential, estimate the watershed response to different rainfall events, quantify the impact of hypothetical flood mitigation scenarios, and identify subwatersheds for the construction of small-scale flood mitigation projects. In phase two, the IFC provided technical reports to the WMAs that evaluated the effectiveness of the constructed practices and the project’s replicability at a larger scale to guide future watershed management efforts.

IWA researchers at IIHR and IFC developed and implemented a new, state-of-the-art watershed-scale hydrologic model, the Generic Hydrologic Overland-Subsurface Toolkit (GHOST), to estimate watershed responses to rainfall events. GHOST considers Iowa’s varied topography, soils, and land use to simulate the hydrologic responses at watersheds over time periods on the order of decades. IWA modelers used GHOST to evaluate the flood reduction benefits expected from both nature-based and structural mitigation strategies for all IWA watersheds. This modeling effort included scenarios based on climate change predictions based on mid-century and late 21st-century projections for Iowa and the Midwest as identified in the Climate Science Special Report. Researchers modified the model parameters to understand the impacts of increasing infiltration in the watershed and to simulate the flood reduction benefits of implementing cover crops, native vegetation (e.g., tall-grass prairie), and distributed storage (farm ponds) located in headwater regions of the watersheds. IFC delivered the results to each WMA in a hydrologic assessment report to assist with strategic flood mitigation practice implementation and to support the WMA's development of long-term watershed management plans to guide future decision-making.

Program Evaluation

The IWA was able to overcome the challenges of a complex administrative system, significant impacts from ongoing flooding along the Missouri River in 2019, and a global pandemic. A critical component of its success was the inclusion of ongoing program evaluation and assessment activities led by the University of Iowa Center for Evaluation and Assessment (CEA). Throughout the entire project, the CEA carried out a strategic plan for conducting surveys and interviews with project partners, WMA board members, landowners, and project coordinators. These results were used to make important program pivots in real time to address areas of concern, identify resource concerns, and enhance the program’s efficiency and effectiveness.