Frontier: Drainage Water Recycling in the Humid Regions of the U.S.: Challenges and Opportunities

HighlightsDrainage water recycling captures and stores agricultural drainage water for reuse as supplemental irrigation.Drainage water recycling can both increase crop production and benefit downstream water quality.Depending on management, drainage water recycling can also provide other complementary benefits.Research needs to advance drainage water recycling are presented and discussed. Keywords: Drainage water quality, Drainage water reuse, Subsurface drainage, Supplemental irrigation, Agricultural resiliency.

Effect of Drainage Water Reuse on Supplementary Irrigation and Drainage Reduction

Drainage water reuse has the potential to supplement irrigation, reduce drainage, and alleviate the area source pollution caused by agricultural drainage. This study aimed to evaluate the effects of influencing factors of drainage water reuse on supplementary irrigation and drainage reduction rates. To evaluate the effects, a water balance model was constructed to describe the irrigation water requirement and drainage water storage of a pond. The irrigation water requirement was calculated using the Penman-Monteith equation and the crop coefficient method while considering field leakage and effective rainfall; the drainage water volume was calculated using the improved Soil Conservation Service (SCS) model. The model was applied to the rice planting area in the Zhanghe Reservoir Irrigation District. Simulation results show that the supplementary irrigation and drainage reduction rates are primarily affected by the ratio of irrigation to drainage areas (RID), the pond volume ratio (PV), and the initial storage ratio (PSi); interactions among the three parameters are also observed. The RID, PV, and PSi contribute approximately 4:3:1 to the average variations in the supplementary irrigation rate. The supplementary irrigation rate increases with the values of PV and PSi but decreases with the increases of RID. For the drainage reduction rate variation, the average contribution percentages of PV and RID are 70% and 10%, respectively. Increasing PV and RID or reducing PSi enhances the drainage reduction rate. Adjusting the combination of parameters PV and RID can simultaneously maximize the supplementary irrigation and drainage reduction rates. Keywords: Drainage reduction, Drainage water reuse, Pond, Supplementary irrigation, Water balance model.