Development of genetic algorithm-based optimization module in WHAT system for hydrograph analysis and model application
Many hydrologic and water quality computer models have been developed and applied to assess hydrologic and water quality impacts of land use changes. These models are typically calibrated and validated prior to their application. The Long-Term Hydrologic Impact Assessment (L-THIA) model was applied...
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Published in | Computers & geosciences Vol. 36; no. 7; pp. 936 - 944 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Kidlington
Elsevier Ltd
01.07.2010
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Many hydrologic and water quality computer models have been developed and applied to assess hydrologic and water quality impacts of land use changes. These models are typically calibrated and validated prior to their application. The Long-Term Hydrologic Impact Assessment (L-THIA) model was applied to the Little Eagle Creek (LEC) watershed and compared with the filtered direct runoff using BFLOW and the Eckhardt digital filter (with a default BFI
max value of 0.80 and filter parameter value of 0.98), both available in the Web GIS-based Hydrograph Analysis Tool, called WHAT. The
R
2 value and the Nash–Sutcliffe coefficient values were 0.68 and 0.64 with BFLOW, and 0.66 and 0.63 with the Eckhardt digital filter. Although these results indicate that the L-THIA model estimates direct runoff reasonably well, the filtered direct runoff values using BFLOW and Eckhardt digital filter with the default BFI
max and filter parameter values do not reflect hydrological and hydrogeological situations in the LEC watershed. Thus, a BFI
max GA-Analyzer module (BFI
max Genetic Algorithm-Analyzer module) was developed and integrated into the WHAT system for determination of the optimum BFI
max parameter and filter parameter of the Eckhardt digital filter. With the automated recession curve analysis method and BFI
max GA-Analyzer module of the WHAT system, the optimum BFI
max value of 0.491 and filter parameter value of 0.987 were determined for the LEC watershed. The comparison of L-THIA estimates with filtered direct runoff using an optimized BFI
max and filter parameter resulted in an
R
2 value of 0.66 and the Nash–Sutcliffe coefficient value of 0.63. However, L-THIA estimates calibrated with the optimized BFI
max and filter parameter increased by 33% and estimated NPS pollutant loadings increased by more than 20%. This indicates L-THIA model direct runoff estimates can be incorrect by 33% and NPS pollutant loading estimation by more than 20%, if the accuracy of the baseflow separation method is not validated for the study watershed prior to model comparison. This study shows the importance of baseflow separation in hydrologic and water quality modeling using the L-THIA model. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0098-3004 1873-7803 |
DOI: | 10.1016/j.cageo.2010.01.004 |