Location: Delta Water Management ResearchTitle: Using rainfall analysis to manage freeboard and increase rainfall capture for multiple-inlet rice irrigation in the Lower Mississippi River Valley
|SMITH, M.CADE - Mississippi State University|
|AVILA, LUIS - Federal University Of Pelotas|
Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2019
Publication Date: 5/31/2019
Citation: Massey, J., Smith, M.C., Adviento-Borbe, A.A., Reba, M.L., Avila, L.A. 2019. Using rainfall analysis to manage freeboard and increase rainfall capture for multiple-inlet rice irrigation in the Lower Mississippi River Valley. Journal of Irrigation and Drainage Engineering. 145(8). https://doi.org/10.1061/%28ASCE%29IR.1943-4774.0001403.
Interpretive Summary: Rice is important to the economies of Arkansas and other rice-growing states in the Lower Mississippi River Valley. Rice also relies heavily on groundwater pumped from the alluvial aquifer that is declining in portions of Arkansas and Mississippi. Results from this study show that if producers maintain approximately one to two inches of freeboard during the rice flood season, an average of two additional inches rainfall can be captured compared to when no freeboard is intentionally managed. This supports university extension recommendations and can be accomplished by raising levee gates while maintaining maximum pumping depth as before. Results from this study help devise management practices that maximize rainfall capture that, in turn, could help alleviate on-going declines in the Mississippi River Valley Alluvial aquifer.
Technical Abstract: Research was conducted to help rice (Oryza sativa L.) farmers increase rainfall capture as a means to offset groundwater use in the Lower Mississippi River Valley (LMRV). The LMRV is where a majority of U.S rice is produced. Kolmogorov-Smirnov (K-S) frequency analysis was used to determine 50 to 99% quantiles for daily rainfall occurring at nine LMRV locations. Next, the rainfall quantiles were used as freeboard settings in a generalized water-balance model that simulates multiple-inlet rice irrigation (MIRI) in a 16-ha field. Compared to when no freeboard was intentionally managed, average irrigation use was reduced by up to 60 mm or 10%. Average rainfall capture (RC) estimates increased from approximately 60 to 80% when at least 28-mm freeboard was maintained throughout an 86-d flood period. Rainfall capture decreased when rain occurred in intense, closely-spaced events. Capture increased when rainfall occurred in more evenly-spaced events. Improved RC and application efficiency (AE) were each responsible for about 50% of total irrigation reductions estimated by the model. Maintaining at least 28-mm freeboard and promptly halting irrigation if runoff occurs, average irrigation reductions of over 30%, relative to single-inlet (SI) flood distribution, are achievable, helping to reduce groundwater withdrawals, energy use, and runoff.