Submitted to: Journal of Agricultural Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2011
Publication Date: 1/20/2012
Citation: Hernandez, J.E., Gowda, P., Howell, T.A., Steiner, J.L., Mojarro, F., Nunez, E.P., Avila, J.R. 2012. Modeling groundwater levels on the Calera Aquifer Region in Central Mexico using ModFLow. Journal of Agricultural Science and Technology. 2(1B):52-61. Interpretive Summary: The Calera Aquifer region is the major source of food production in the State of Zacatecas, Mexico. Irrigated agriculture in the region accounts for about 80% of the groundwater extracted from the Calera aquifer. Due to limited rainfall and low water use efficiency, groundwater is being depleted at an unsustainable rate. In this study, we evaluated a conceptual groundwater model for the Calera Aquifer region using the MODFLOW-2000. Performance statistics indicated that the conceptual model performed well in predicting historical groundwater levels in the central portion of the region. However, further improvements in the conceptual model are needed to improve predictions in peripheral areas of the Calera Aquifer region.
Technical Abstract: A conceptual model for the Calera Aquifer has been created to represent the aquifer system beneath the Calera Aquifer Region (CAR) in the State of Zacatecas, Mexico. The CAR area was uniformly partitioned into a 500 X 500 m grid generating a high resolution model that represented the natural boundaries of the aquifer. A computer model was calibrated and validated to verify output from the model corresponding to situations that matched the historical aquifer performance. Predicted groundwater levels were compared with measured data collected from nine observation wells between 1954 and 2004 to evaluate model performance. The main objective of this study was to develop and evaluate a groundwater modeling system using ModFlow-2000 for the CAR. Performance statistics indicated that the model performed well in simulating historic groundwater levels in the central part of the CAR where irrigated agriculture was concentrated. Results evaluation yielded average coefficients of determination of 0.81 and 0.67 and root mean square error values lower than 25.1 m and 25.9 m for the calibration and validation processes, respectively. These results are indicative of a good agreement between predicted and observed groundwater levels. However, further improvements in the conceptual model may be needed to improve predictions in other parts of the CAR for evaluating alternative groundwater management strategies.