Ecohydrology

Deep percolation (DP) is important for groundwater recharge in agricultural areas, yet few studies have investigated the connections between surface water and shallow groundwater in floodplain agriculture valleys. In this study, field observations were used to assess soil water transport through and below the root zone in a floodplain irrigated valley. Study objectives were to: 1) determine deep percolation following irrigation, and 2) characterize the shallow aquifer response to deep percolation. Two oat-wheatgrass fields (fields 1 and 2) near Española in north-central New Mexico were established in two predominant local soil types (Werlog clay loam and Fruitland sandy loam). A water balance method was used to calculate irrigation-deep percolation that ranged from 0 to 157 mm in field 1, and from 0 to 113 mm in field 2. Deep percolation resulted in a transient water table rise during most irrigation events that ranged from 1 to 244 mm in field 1, and from 1 to 97 mm in field 2. Study results add to the understanding of the relationships between irrigation, soil water dynamics, and water table fluctuations in a floodplain agriculture valley.