Title: A modeling approach to evaluate impacts of changing irrigation and cropping systems on reducing groundwater depletion in the Calera watershed, Zacatecas, Mexico Authors
|Mojarro, Franscico -|
|Carrasco, Avila -|
|Bautista-Capetillo, C -|
|Echavarria-Chairez, F -|
|Kanemasu, Ed -|
|Wagner, K -|
|Hernandez, J -|
Submitted to: International Soil and Water Conservation Conference
Publication Type: Abstract Only
Publication Acceptance Date: March 28, 2012
Publication Date: N/A
Interpretive Summary: Abstract only.
Technical Abstract: Groundwater is the main source of water in the semi-arid Calera watershed, located in Zacatecas State, Mexico. Due to increasing population, industrial growth, and increased irrigation, groundwater extraction exceeds recharge rates, so evaluation of new policy, technology, and management options is needed. In the Calera watershed area the native flora has been in decline for decades. In this study, the Soil and Water Assessment Tool (SWAT), an extensively used hydrologic model was calibrated and used as a tool to evaluate irrigation, land use and management systems to determine practical scenarios which may guide policy planning and lead to management options to minimize groundwater depletion rates. A biomass and water balance approach, which has potential for calibration of hydrologic models in ungauged or data-scarce watersheds, was used. The model reproduced crop biomass, evapotranspiration (ET), and deep aquifer recharge rates reasonably well. The main model simulations included conversion to more efficient irrigation systems, conversion of irrigated high water use crops like chili to low water requirement crops like canola, and conversion of rainfed beans and corn crops to native grasses. Overall, the best combined scenario results showed a maximum of 26% reduction in groundwater depletion rates, which is about half of the 50% target reduction depletion rates by 2021 proposed by the Federal government. It is clear that the solution to arrive at a sustainable use of the Calera aquifer will require more than switching to better irrigation systems, crops with lower water requirements, and range land restoration.