The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of potential futur... more The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed on a monthly basis for 1968-87 and 1988-97, respectively; R2 and Nash-Sutcliffe simulation efficiency (E) values computed for the monthly comparisons were 0.74 and
The size, scale, and number of subwatersheds can affect a watershed modeling process and subseque... more The size, scale, and number of subwatersheds can affect a watershed modeling process and subsequent results. The objective of this study was to determine the appropriate level of subwatershed division for simulating sediment yield. The Soil and Water Assessment Tool (SWAT) model with a geographic information system interface (AVSWAT) was applied to four Iowa watersheds that varied greatly in drainage
2010 4th International Conference on Bioinformatics and Biomedical Engineering, 2010
... Mahesh K. Sahu Dept. of Civil, Constr. and Environmental Engineering Iowa State University Am... more ... Mahesh K. Sahu Dept. of Civil, Constr. and Environmental Engineering Iowa State University Ames, Iowa, USA ... It has been validated for various watersheds throughout USA [3], [4]. Model components were described in detail by Arnold et al. ...
Journal of The American Water Resources Association - J AM WATER RESOUR ASSOC, 2006
The Soil and Water Assessment Tool (SWAT) model was used to assess the effects of potential futur... more The Soil and Water Assessment Tool (SWAT) model was used to assess the effects of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed using monthly stream flows for 1968-1987 and 1988-1997, respectively. The R2 and Nash-Sutcliffe simulation efficiency values computed for the monthly comparisons were 0.74 and 0.69 for the calibration period and 0.82 and 0.81 for the validation period. The effects of nine 30-year (1968 to 1997) sensitivity runs and six climate change scenarios were then analyzed, relative to a scenario baseline. A doubling of atmospheric CO2 to 660 ppmv (while holding other climate variables constant) resulted in a 36 percent increase in average annual streamflow while average annual flow changes of -49, -26, 28, and 58 percent were predicted for precipitation change scenarios of -20, -10, 10, and 20 percent, respectively. Mean annual streamflow changes of 51, 10, 2, -6, 38, an...
A two-dimensional reservoir toxics model is essential to establishing effective water resources m... more A two-dimensional reservoir toxics model is essential to establishing effective water resources management and protection. In a reservoir, the fate of a toxic chemical is closely connected with flow regimes and circulation patterns. To better understand the kinetic processes and persistence and predict the dissipation of toxic contaminants in the reservoir during a spill or storm runoff event, a toxics submodel was developed and incorporated into an existing laterally integrated hydrodynamics and transport model. The toxics submodel describes the physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical. The two-dimensional toxicant simulation model was applied to Shasta Reservoir in California to simulate the physico-chemical processes and fate of a volatile toxic compound, methyl isothiocyanate (MITC), during a chemical spill into the Sacramento River in 1991. The predicted MITC concentrations were compared with those observed. The effect of reservoir flow regimes on the transport and fate of the toxic substance was investigated. The results suggested that the persistence of MITC is significantly influenced by different flow regimes. Methyl isothiocyanate is more persistent in the reservoir under an interflow condition due to reduced volatilization from deep layers than under an overflow condition. In the overflow situation, the plume moved more slowly toward the dam and experienced greater dissipation. This analysis can assist in toxic spill control and reservoir management, including field sampling and closure of water intakes.
A sensitivity analysis is performed to evaluate river temperature variations in response to chang... more A sensitivity analysis is performed to evaluate river temperature variations in response to changes in hydraulic and meteorological conditions. The effects of instream flow, river geometry, and weather factors on daily mean and daily maximum river temperatures are quantified by analytical solutions to a simplified model. The influence coefficient method is used to determine river temperature sensitivity. The sensitivity analysis presents quantitative evidence that river temperatures are more sensitive to instream flowrate, upstream inflow temperature, air temperature, humidity and solar radiation than to other parameters including wind speed and channel geometry and morphometry. It is found that the sensitivity of river temperatures to flow is as significant as that to weather. Daily maximum river temperature is more sensitive to flowrate than daily mean temperature. Adapting the concept of 'diminishing returns', a critical instream flowrate is identified, which divides high and low sensitivity of water temperatures to flowrate. The critical flowrate can be used to determine practically achievable and economically feasible flow requirements for summer river temperature control. The sensitivity results can assist in streamflow management and reservoir operation for protections of habitat and aquatic environment.
The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of potential futur... more The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed on a monthly basis for 1968-87 and 1988-97, respectively; R2 and Nash-Sutcliffe simulation efficiency (E) values computed for the monthly comparisons were 0.74 and
The size, scale, and number of subwatersheds can affect a watershed modeling process and subseque... more The size, scale, and number of subwatersheds can affect a watershed modeling process and subsequent results. The objective of this study was to determine the appropriate level of subwatershed division for simulating sediment yield. The Soil and Water Assessment Tool (SWAT) model with a geographic information system interface (AVSWAT) was applied to four Iowa watersheds that varied greatly in drainage
2010 4th International Conference on Bioinformatics and Biomedical Engineering, 2010
... Mahesh K. Sahu Dept. of Civil, Constr. and Environmental Engineering Iowa State University Am... more ... Mahesh K. Sahu Dept. of Civil, Constr. and Environmental Engineering Iowa State University Ames, Iowa, USA ... It has been validated for various watersheds throughout USA [3], [4]. Model components were described in detail by Arnold et al. ...
Journal of The American Water Resources Association - J AM WATER RESOUR ASSOC, 2006
The Soil and Water Assessment Tool (SWAT) model was used to assess the effects of potential futur... more The Soil and Water Assessment Tool (SWAT) model was used to assess the effects of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed using monthly stream flows for 1968-1987 and 1988-1997, respectively. The R2 and Nash-Sutcliffe simulation efficiency values computed for the monthly comparisons were 0.74 and 0.69 for the calibration period and 0.82 and 0.81 for the validation period. The effects of nine 30-year (1968 to 1997) sensitivity runs and six climate change scenarios were then analyzed, relative to a scenario baseline. A doubling of atmospheric CO2 to 660 ppmv (while holding other climate variables constant) resulted in a 36 percent increase in average annual streamflow while average annual flow changes of -49, -26, 28, and 58 percent were predicted for precipitation change scenarios of -20, -10, 10, and 20 percent, respectively. Mean annual streamflow changes of 51, 10, 2, -6, 38, an...
A two-dimensional reservoir toxics model is essential to establishing effective water resources m... more A two-dimensional reservoir toxics model is essential to establishing effective water resources management and protection. In a reservoir, the fate of a toxic chemical is closely connected with flow regimes and circulation patterns. To better understand the kinetic processes and persistence and predict the dissipation of toxic contaminants in the reservoir during a spill or storm runoff event, a toxics submodel was developed and incorporated into an existing laterally integrated hydrodynamics and transport model. The toxics submodel describes the physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical. The two-dimensional toxicant simulation model was applied to Shasta Reservoir in California to simulate the physico-chemical processes and fate of a volatile toxic compound, methyl isothiocyanate (MITC), during a chemical spill into the Sacramento River in 1991. The predicted MITC concentrations were compared with those observed. The effect of reservoir flow regimes on the transport and fate of the toxic substance was investigated. The results suggested that the persistence of MITC is significantly influenced by different flow regimes. Methyl isothiocyanate is more persistent in the reservoir under an interflow condition due to reduced volatilization from deep layers than under an overflow condition. In the overflow situation, the plume moved more slowly toward the dam and experienced greater dissipation. This analysis can assist in toxic spill control and reservoir management, including field sampling and closure of water intakes.
A sensitivity analysis is performed to evaluate river temperature variations in response to chang... more A sensitivity analysis is performed to evaluate river temperature variations in response to changes in hydraulic and meteorological conditions. The effects of instream flow, river geometry, and weather factors on daily mean and daily maximum river temperatures are quantified by analytical solutions to a simplified model. The influence coefficient method is used to determine river temperature sensitivity. The sensitivity analysis presents quantitative evidence that river temperatures are more sensitive to instream flowrate, upstream inflow temperature, air temperature, humidity and solar radiation than to other parameters including wind speed and channel geometry and morphometry. It is found that the sensitivity of river temperatures to flow is as significant as that to weather. Daily maximum river temperature is more sensitive to flowrate than daily mean temperature. Adapting the concept of 'diminishing returns', a critical instream flowrate is identified, which divides high and low sensitivity of water temperatures to flowrate. The critical flowrate can be used to determine practically achievable and economically feasible flow requirements for summer river temperature control. The sensitivity results can assist in streamflow management and reservoir operation for protections of habitat and aquatic environment.
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