Assessing the cumulative impact of on-farm reservoirs on modeled surface hydrology

Authors: PERIN, VINICIUS - North Carolina State University; TULBURE, MIRELA - North Carolina State University; FANG, SHIQI - North Carolina State University; ARMUGAM, A.SANKARASUBRAM - North Carolina State University; Reba, Michele; YAEGER, MARY - University Of Memphis

Submitted to: Hydrology and Earth System Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: On-farm reservoirs (OFRs) are essential water bodies to meet irrigation needs. Despite their importance to crop irrigation, OFRs can have a cumulative impact on surface hydrology by decreasing flow and peak flow. There is limited knowledge on the spatial and temporal variability of the OFRs' impacts on surface hydrology. The latest developments in the Soil Water Assessment Tool+ (SWAT+) in combination with a novel remote sensing-based algorithm was used to assess the impacts of OFRs in a small sub-watershed located in eastern Arkansas. Our results show that the presence of the OFRs on the watershed may decrease annual flow on average between 14 and 24%, and the mean reduction in peak flow could vary between 43 and 60%. We provide a new framework that can support water agencies with information to assess the cumulative impacts of OFRs on the watersheds where they are constructed, aiming to support surface water resources management.

Technical Abstract: On-farm reservoirs (OFRs) are essential water bodies to meet global irrigation needs. Farmers use OFRs to store water from precipitation and runoff during the rainy season to irrigate their crops during the dry season. Despite their importance to crop irrigation, OFRs can have a cumulative impact on surface hydrology by decreasing flow and peak flow. Nonetheless, there is limited knowledge on the spatial and temporal variability of the OFRs' impacts on surface hydrology. Therefore, we leveraged the latest developments in the Soil Water Assessment Tool+ (SWAT+) in combination with a novel remote sensing-based algorithm—used to monitor the OFRs dynamics—to assess the impacts of OFRs in a small sub-watershed located in eastern Arkansas, which is the third most irrigated state in the USA. Our results show that the presence of the OFRs on the watershed may decrease annual flow on average between 14 and 24%, and the mean reduction in peak flow could vary between 43 and 60%. In addition, the impact of the OFRs is not equally distributed across the watershed, and it varies according to the OFRs spatial distribution, and their surface area (i.e., water storage capacity). We provide a new framework that can support water agencies with information to assess the cumulative impacts of OFRs on the watersheds where they are constructed, aiming to support surface water resources management. This is relevant as the number of OFRs is expected to increase globally, partially to adapt to climate change under severe drought conditions.