Riley Post, University of Iowa – Can Little Ponds Fight Big Floods

Fighting floods is becoming a pressing issue.

Riley Post, PhD candidate and graduate research fellow at the University of Iowa, determines one way to do so.

Riley Post, P.E. is a PhD Candidate and Graduate Research Fellow in Civil Engineering within the Iowa Flood Center at the University of Iowa. His doctoral research centers on quantifying uncertainty in hydrologic systems (i.e., uncertainty in the collection of radar rainfall data, rainfall forecasts, hydrologic models, and the operation of hydrologic systems) to tackle water related problems facing society. His dissertation is focused on the optimization of distributed reservoir networks for stream flow reduction in the face of these sources of uncertainty. His work is funded by the National Science Foundation Graduate Research Fellowship Program (NSF-GRFP), the University of Iowa Graduate College Post-Comprehensive Fellowship, and the Douglas A. Wallace Fellowship.

Prior to starting his PhD in 2020, Riley worked for the Rock Island District of the US Army Corps of Engineers in the Water Control Section. In this position he spent over a decade operating flood control reservoirs and navigation locks and dams across the upper Midwest.

Can Little Ponds Fight Big Floods

Major flooding has been in the news across the United States in 2023. Whether caused by snowpack in the West, spring rains along the Mississippi River in the Midwest, or torrential summer thunderstorms in the Northeast, these disasters have cost the United States lives, livelihoods, and billions of dollars.

Rainfall patterns are changing, and, in many places, storms are dropping more rain in shorter periods of time, leading to more frequent flooding. The US has over 91,000 dams, most of which are small and impound ponds that are not used for flood control. By adding gated outlets to some of these locations and operating them as a system, intense rainfall can be kept in the upper reaches of a watershed before being released. This local scale storage of rainfall allows for a more nuanced approach to watershed management, where small areas of a basin can be targeted to store water, while others are allowed to drain their ponds, making room for the next storm. We refer to this flood fighting method as “activated distributed storage” and our work has shown that it can reduce flood flows by up to 70%. Not only does storing water in the ponds reduce downstream flooding, but in many cases, it can delay the timing of flood crests, giving downstream communities more time to roll out flood fighting measures before flood waters arrive.

As climate change makes rainfall more intense, new tools for flood fighting will be needed. Activated distributed storage uses already existing infrastructure to fight a growing problem and looks to a hold a lot of potential in a warming future.