Calibration of SWAT2009 Using Crop Biomass, Evapotranspiration, and Deep Recharge: Calera Watershed in Zacatecas, Mexico Case Study

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 (R 2 ), 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.

Projected Climate Could Increase Water Yield and Cotton Yield but Decrease Winter Wheat and Sorghum Yield in an Agricultural Watershed in Oklahoma

“…The values were then manually adjusted until the PB for the crop models reached satisfactory values for cotton (−4.5%), grain sorghum (−27.3%), and winter wheat (−6.0%) from the year 1986 to 2010 ( Figure 4). Manual calibration of the model for yields of cotton, grain sorghum, and winter wheat followed successful hydrologic calibration using percent bias as a measure of performance, which is popularly used in crop-yield modeling studies [41,42]. Yield data were based on the Oklahoma State University experimented variety trials data for the years 2005 to 2010 (http://croptrials.okstate.edu/) and county level crop yield data for the years 1986 to 2005 (Oklahoma Agricultural Statistics database, http://digitalprairie.ok.gov/cdm/ref/collection/stgovpub/id/11177).…”

Hydrological responses of land use change from cotton (Gossypium hirsutum L.) to cellulosic bioenergy crops in the Southern High Plains of Texas,USA

“…After achieving a satisfactory streamflow calibration, the model was further calibrated for prediction of cotton lint yield under both irrigated and dryland systems to obtain a good match between the simulated and reported cotton lint yields. Previous SWAT modeling studies that performed crop yield calibration (Hu et al, 2007;Nair et al, 2011;Sarkar et al, 2011;Avila-Carrasco et al, 2012) suggested adjusting the biomass/ energy ratio (BIO_E) and maximum leaf area index (BLAI) to calibrate the SWAT model for crop yield prediction. Among these studies, Sarkar et al Harvest and Kill parameters (Kill on July 1) Default *Auto-irrigation was simulated in appropriate proportion of cotton area based on county cotton irrigation acreage summary reports.…”

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“…La altitud del acuífero Calera varía entre los 600 y 2000 m, el cual presenta unidades de origen volcánico pertenecientes a la Sierra Madre Occidental, además se forma por materiales aluviales y lacustres de arcilla, limo, arena y grava cementados con arcilla calcárea. La litología corresponde a rocas ígneas, calizas, dolomitas y metamórficas fracturadas por movimientos tectónicos (Ávila et al 2012;Hernández et al 2012;Navarro et al 2005). El tipo de suelo con mayor predominio es el Catañozen lúvico ya que es producto del arrastre del material aluvial que conforma la región (INEGI, 2014).…”