TY - GEN
T1 - Estimate irrigation water use by data assimilation
AU - Wang, Dingbao
AU - Cai, Ximing
PY - 2007
Y1 - 2007
N2 - Water use is usually metered in municipal and industrial sectors but not in agriculture. The survey data of irrigation water use are highly variable in quality, depending on reporting requirements at the level of the state, the watershed, or the irrigation project. In hydrologic-agronomic models, irrigation is either treated as an estimated fixed input or determined by the model through certain prescribed empirical criteria. This paper presents an approach for estimating irrigation water use based on a hydro-agronomic model (Soil Water Atmosphere Plant model-SWAP) and crop evapotranspiration (ET) assessed from remote sensing utilizing the data surface energy balance algorithm for land. A coupled forward-inverse procedure is implemented for the analysis. The forward procedure is to assimilate the ET estimation into the hydro-agronomic model through the ensemble Kalman filter, which is an efficient data assimilation method for complex nonlinear dynamic models. The inverse procedure is to search irrigation scheduling using a genetic algorithm (GA). The two procedures are tightly coupled through the objective function, which is based on the likelihood function assessed from the data assimilation framework by maximizing the joint distribution of all "observed" crop ET. The forward-inverse framework incorporates model errors and observation errors, which allows the assessment of the inaccuracy of the irrigation estimate. The soil hydraulic properties of the case study area, which are the most sensitive parameters of the SWAP model, are estimated by genetic algorithm based on the available soil survey data and the in-site soil moisture measurement in a grass land.
AB - Water use is usually metered in municipal and industrial sectors but not in agriculture. The survey data of irrigation water use are highly variable in quality, depending on reporting requirements at the level of the state, the watershed, or the irrigation project. In hydrologic-agronomic models, irrigation is either treated as an estimated fixed input or determined by the model through certain prescribed empirical criteria. This paper presents an approach for estimating irrigation water use based on a hydro-agronomic model (Soil Water Atmosphere Plant model-SWAP) and crop evapotranspiration (ET) assessed from remote sensing utilizing the data surface energy balance algorithm for land. A coupled forward-inverse procedure is implemented for the analysis. The forward procedure is to assimilate the ET estimation into the hydro-agronomic model through the ensemble Kalman filter, which is an efficient data assimilation method for complex nonlinear dynamic models. The inverse procedure is to search irrigation scheduling using a genetic algorithm (GA). The two procedures are tightly coupled through the objective function, which is based on the likelihood function assessed from the data assimilation framework by maximizing the joint distribution of all "observed" crop ET. The forward-inverse framework incorporates model errors and observation errors, which allows the assessment of the inaccuracy of the irrigation estimate. The soil hydraulic properties of the case study area, which are the most sensitive parameters of the SWAP model, are estimated by genetic algorithm based on the available soil survey data and the in-site soil moisture measurement in a grass land.
KW - Algorithms
KW - Data analysis
KW - Estimation
KW - Irrigation
KW - Remote sensing
KW - Water use
UR - http://www.scopus.com/inward/record.url?scp=84863367530&partnerID=8YFLogxK
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U2 - 10.1061/40856(200)271
DO - 10.1061/40856(200)271
M3 - Conference contribution
AN - SCOPUS:84863367530
SN - 0784408564
SN - 9780784408568
T3 - Examining the Confluence of Environmental and Water Concerns - Proceedings of the World Environmental and Water Resources Congress 2006
BT - Examining the Confluence of Environmental and Water Concerns - Proceedings of the World Environmental and Water Resources Congress 2006
T2 - World Environmental and Water Resources Congress 2006: Examining the Confluence of Environmental and Water Concerns
Y2 - 21 May 2006 through 25 May 2006
ER -