Water distribution in traditionally irrigated valleys under different scenarios of water availability in Northern New Mexico

Abstract:

Population growth and water scarcity are factors that increase pressures on water resources of the semiarid southwestern United States. In these areas, groundwater recharge and delayed return flow to rivers are hydrological benefits of traditional irrigation systems. A broad spatial-temporal analysis of the dynamics of surface water and groundwater interactions is necessary to improve water planning and management. Our study at three northern New Mexico agricultural valleys with low to high water availability was carried out to characterize surface water and groundwater interactions and to quantify different water budget components. The study sites were instrumented to collect weather data, water flows from rivers and acequias, shallow groundwater level fluctuations, soil physical properties and irrigation and crop management on irrigated lands. From one crop field of our study sites, results showed up to 38 cm of water level response after the beginning of an irrigation event. Other results in our study sites, showed water level response up to 80 cm after canal flow started and ditch seepage of 12% of the total valley surface water flow. Preliminary field scale results from our three study sites showed that deep percolation from irrigation is the major component of the total water budget with 43, 46 and 52% from low, medium and high water availability sites respectively. This farm scale study revealed that, water availability drives the amount of applied water and the irrigation schedule on the farms that in turn drive deep percolation and shallow aquifer recharge. It appears that traditional irrigation is an important source of groundwater recharge in our study valleys. From the ongoing study, we expect to get detailed information about the water distribution over larger spatial scales using field measurements and geographic information systems-based land use classification.