Abstract
The continuous growth of irrigated agricultural has resulted in decline of groundwater levels in many regions of Maryland and the Mid–Atlantic. The main objective of this study was to use crop water productivity as an index to evaluate different irrigation strategies including rainfed, groundwater, and recycled water use. The Soil and Water Assessment Tool (SWAT) was used to simulate the watershed hydrology and crop yield. It was used to estimate corn and soybean water productivity using different irrigation sources, including treated wastewater from adjacent wastewater treatment plants (WWTPs). The SWAT model was able to estimate crop water productivity at both subbasin and hydrologic response unit (HRU) levels. Results suggest that using treated wastewater as supplemental irrigation can provide opportunities for improving water productivity and save fresh groundwater sources. The total water productivity (irrigation and rainfall) values for corn and soybean were found to be 0.617 kg/m3 and 0.173 kg/m3, respectively, while the water productivity values for rainfall plus treated wastewater use were found to be 0.713 kg/m3 and 0.37 kg/m3 for corn and soybean, respectively. The outcomes of this study provide information regarding enhancing water management in similar physiographic regions, especially in areas where crop productivity is low due to limited freshwater availability.
Highlights
In recent years, the Mid–Atlantic region has been experiencing intermittent rainfall with higher temperatures, especially during the growing season
The results demonstrated that the Soil and Water Assessment Tool (SWAT) model is a useful tool in calculating water productivity at the watershed scale
This study explored the treated wastewater use potentiality to increase crop water productivity and provides information for future policy implications
Summary
The Mid–Atlantic region has been experiencing intermittent rainfall with higher temperatures, especially during the growing season (summertime). While models of future climate predict a moderate increase in annual precipitation for the Mid–Atlantic, it will happen mainly during winter and early spring [3], over fewer more extreme events, and with higher summer temperatures that promote evapotranspiration (ET). The water permit database for Maryland indicated that the number of pumping wells used for crop irrigation has increased in the past few years to meet the higher crop water demand [10]. These factors, combined with population growth and high rate of urbanization, have resulted in the depletion of aquifers, especially in summer months. These declines, if prolonged, could have a significant impact on the sustainable freshwater supply in future
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