Calibration of SWAT2009 using crop biomass, evapotranspiration, and deep recharge: Calera watershed in Zacatecas, Mexico case study

Authors: AVILA-CARRASCO, JOSE - Autonomous University Of Zacatecas; MOJARRO, FRANCISCO - Autonomous University Of Zacatecas; Moriasi, Daniel; Gowda, Prasanna; BAUTISTA-CAPETILLO, CARLOS - Autonomous University Of Zacatecas; ECHAVARRIA-CHAIREZ, FRANCISCO - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP); Garbrecht, Jurgen; Steiner, Jean; Howell, Terry; KANEMASU, EDWARD - University Of Georgia; Verser, Jerry - Alan; WAGNER, KEVIN - Texas A&M University; HERNANDEZ, JAIRO - Boise State University

Submitted to: Journal of Water Resource and Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2012
Publication Date: 7/1/2012
Citation: Avila-Carrasco, J.R., Mojarro, F.D., Moriasi, D.N., Gowda, P., Bautista-Capetillo, C., Echavarria-Chairez, F.G., Garbrecht, J.D., Steiner, J.L., Howell, T.A., Kanemasu, E.T., Verser, J.A., Wagner, K., Hernandez, J. 2012. Calibration of SWAT2009 using crop biomass, evapotranspiration, and deep recharge: Calera watershed in Zacatecas, Mexico case study. Journal of Water Resource and Protection. 4:439-450.

Interpretive Summary: Hydrologic models are cost-effective tools that are increasingly used to evaluate the impacts of alternative management practices and climate change on quantity and quality of water resources. However, data, which are commonly used for calibrating hydrologic models, are not available in many ungauged watersheds worldwide. This paper describes a novel calibration methodology that uses biomass and water balance approach using the Calera watershed as the case study. Due to increasing population, rapid industrial growth, and increased irrigation to meet growing food demand, groundwater extraction in the Calera watershed located in the State of Zacatecas, Mexico, exceeds recharge rates. Therefore, development and evaluation of alternative water management strategies are needed for sustainable development of the region. The Soil and Water Assessment Tool (SWAT) model was selected for this purpose because it has been successfully used worldwide and because of the potential for future linkage with the MODFLOW groundwater model. Long-term annual average actual evapotranspiration (AET), and deep aquifer recharge rates and plant biomass values for each of the land use and irrigation systems in the watershed were used as targets for calibration. The calibrated SWAT model simulated AET, deep aquifer recharge rates, and plant biomass for each land use and irrigation system within 10% of the target values. The calibrated SWAT model will be used to evaluate alternative water management scenarios for the Calera watershed to determine cost-effective management systems for policy and decision making. In addition, considering the relative ease in developing calibration data and excellent performance statistics, the calibration methodology proposed in this study may have the potential to be used for ungauged or data-scare agricultural watersheds in many parts of the world.

Technical Abstract: Groundwater is the main source of water in the semi-arid Calera watershed, located in the State of Zacatecas, Mexico. Due to increasing population, rapid industrial growth, and increased irrigation to meet growing food demand, groundwater extraction in the Calera watershed are exceeding recharge rates. Therefore, development and evaluation of alternative water management strategies are needed for sustainable development of the region. The Soil and Water Assessment Tool (SWAT) model was selected for this purpose as it has been used to simulate a wide range of agricultural production, the extensive testing and application in diverse watersheds worldwide, and the potential for future linkage of this model to groundwater models. However, crucial flow data which are commonly used for calibrating hydrologic models are not available in this watershed. This paper describes a novel calibration methodology that uses biomass and water balance approach which has potential for calibration of hydrologic models in ungauged or data-scarce watersheds, which are prevalent in many parts of the world. Estimated long-term annual average actual evapotranspiration (AET), and deep aquifer recharge rates and plant biomass values based on the expert knowledge of researchers and managers in the watershed were used as targets for calibration. The model performance was assessed using the Nash-Sutcliffe efficiency coefficient (NSE), coefficient of determination (R2), and percent bias (PBIAS, %) statistics. On average, the calibrated SWAT model yielded annual Nash-Sutcliffe efficiency coefficient values of 0.95, 0.99, and 0.85 for AET, recharge, and biomass, respectively. The coefficient of determination, values for AET, recharge, and biomass were 0.95, 0.94, and 0.99 respectively. The percent bias values of ±2.21%, ±0.18%, and ±0.96% for AET, recharge, and biomass, respectively, indicated that the model reproduced the calibration target values of the three water budget variables within an acceptable value of ± 10.0%. Therefore, it is concluded that the calibrated SWAT model can be used in evaluating alternative water management scenarios for the Calera watershed without further validation. Considering the relative ease in developing calibration data and excellent performance statistics, the calibration methodology proposed in this study may have the potential to be used for ungauged or data-scare agricultural watersheds that are prevalent in many parts of the world.