Volume 09,Issue 01

Genetic Algorithm for Determining Optimal Unit Hydrograph for Harpeth River Watershed, Tennessee

Authors

Tareq Jamal Chy

Abstract
The unit hydrograph for a watershed plays a significant role in predicting the flood hydrographs of any duration precipitation event, which can be used to calculate the peak flow for designing hydraulic structure to save the area from flooding. The main objective of this study was to obtain an optimal unit hydrograph from twenty field data-based unit hydrographs for the Harpeth River watershed. To attain this objective, field flow data for three years was collected, and twenty random events were drawn to get the flood hydrographs. The flood hydrographs were converted into direct runoff hydrographs and then unit hydrographs. The gamma distribution function was used to get the optimal unit hydrograph through the genetic algorithm for getting optimized values of shift and scale parameters of the distribution. Applying the genetic algorithm, the obtained values of these parameters were 6.86 and 4.03, using the objective function to minimize the root mean square error of peak flow values between filed data-based unit hydrographs and optimal unit hydrographs. To sum up, heuristic optimization, like a genetic algorithm (GA), can be used to optimize gamma distribution parameters due to the difficulty in optimizing it using traditional methods like maximum likelihood and method of moments.

Keyword: Unit Hydrograph, Optimization, Genetic Algorithm, Flood.

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