Surface Water and Ground Water Interactions In An Irrigated Valley In Northern New Mexico

Deep percolation from irrigated corridors can have multiple hydrological benefits including aquifer recharge, temporary storage, and delayed return flow. A study aimed to characterize hydrological interactions between surface water and shallow groundwater is being conducted in the irrigated corridor between the Alcalde main irrigation ditch and the Rio Grande in northern New Mexico. We conducted impoundment tests along sections of the ditch and inflow-outflow tests along the entire ditch to calculate ditch seepage rate. We installed 22 experimental wells and along with 18 collaborator-domestic wells equipped them with water level loggers to measure water level fluctuations along the entire valley. We installed stage-measurement stations along the ditch and the river to measure ditch and river water stage and for calculating ditch flow. We calculated deep percolation in apple and alfalfa crop fields following flood irrigation, common types of crops and irrigation in the valley. The continuum of water transport through the vadose zone and shallow groundwater response to flood irrigation was characterized and wetting front velocity was calculated for different soils. Ditch seepage ranged from 12% to 16% over the entire ditch. An average of 32 cfs flow was calculated in the ditch during the irrigation season. Deep percolation of 15% to 60% was calculated from crop fields depending on soil properties and irrigation depth. The average velocity of propagation of the wetting front ranged from 10 cm/h to 375 cm/h depending on soil type. The Hydrus 1-d model was used to obtain the hydraulic parameters of different soil types that are being used in expanding plot results to larger spatial areas. Modflow is being used to estimate groundwater flow and return flow to the river at the larger valley scale. A System Dynamics model will be used to expand the field-measured results to the regional scale.