A hydrogeologic investigation was completed of the alluvial aquifer near the Osceola County Rural Water System (OCRWS) H-Series well-field, located in Osceola County, Iowa. The primary purpose of the investigation was to quantify drought resiliency benefits of engineered systems on a well-field scale through the use of a groundwater model. Specifically, a groundwater flow model was developed for the OCRWS H-Series well-field to quantify groundwater withdrawal and storage benefits of:
• One rock riffle structure placed within the well-field
• Two rock riffle structures placed within the well-field
• An excavated, historic river channel system combined with one rock riffle structure
The objective of these engineered systems is to increase the groundwater storage within the aquifer. Riffles and channel systems provide additional groundwater storage during periods of normal or above normal precipitation by raising the stage of the river. This additional storage, reflected in groundwater heads, is then available to maintain water production during a drought.
Groundwater model results showed that all three of the engineered systems quantified substantially improved groundwater storage and induced recharge during the drought simulations. While each system was shown to influence the aquifer, benefits to groundwater storage and induced recharge from the two riffle system was shown to provide the greatest amount of drought resiliency benefit. Through the use of a cost-benefit analysis, the two riffle system was also shown to be the most cost-effective method in this study in terms of achieving additional groundwater storage and induced recharge to the aquifer.