This paper presents the results of employing a real-coded genetic algorithm (GA) to the problem of determining the optimal unit pulse response function (UPRF) using the historical data from watersheds. The existing li...
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This paper presents the results of employing a real-coded genetic algorithm (GA) to the problem of determining the optimal unit pulse response function (UPRF) using the historical data from watersheds. The existing linear programming (LP) formulation has been modified, and a new problem formulation is proposed. The proposed problem formulation consists of fewer decision variables, only one constraint, and a non-linear objective function. The proposed problem formulation can be used to determine an optimal UPRF of a watershed from a single storm or a composite UPRF from multiple storms. The proposed problem formulation coupled with the solution technique of real-coded GA is tested using the effective rainfall and runoff data derived from two different watersheds and the results are compared with those reported earlier by others using LP methods. The model performance is evaluated using a wide range of standard statistical measures. The results obtained in this study indicate that the real-coded GA can be a suitable alternative to the problem of determining an optimal UPRF from a watershed. The proposed problem formulation when solved using real-coded GA resulted in smoother optimal UPRF without the need of additional constraints. The proposed problem formulation can be particularly useful in determining the optimal composite UPRF from multiple storms in large watersheds having large time bases due to its limited number of decision variables and constraints. (c) 2004 Elsevier B.V. All rights reserved.
This article derives the unit pulse response functions (unit hydrographs (UHs)) for the quick and slow runoff components of streamflow (quick runoff: direct or surface runoff;slow runoff: the sum of rapid subsurface, ...
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This article derives the unit pulse response functions (unit hydrographs (UHs)) for the quick and slow runoff components of streamflow (quick runoff: direct or surface runoff;slow runoff: the sum of rapid subsurface, delayed subsurface, and groundwater runoffs) using the model of three serial tanks with a parallel tank. The interdependence between the tanks is described by exponential functions of the model's parameters. The parameters are identified using the Simplex method. Ln comparison to traditional unit hydrograph (TUH) methods, the proposed UH method has the following advantages: (1) it can be used to separate quick and slow streamflow components;(2) it is appropriate for forecasting streamflow hydrographs produced by various storms such as single-peak storms and multi-peak storms without resorting to changing model's parameters;and (3) it does not require either an a priori calculation of rainfall excess or baseflow separation for deriving the UH. The TUH models such as the Sherman model and the Nash model with three cascade reservoirs are particular cases of the proposed model. The applicability and validity of the proposed model are verified using observed rainfall-streamflow data from an actual basin. The resulting computed streamflows show a good correspondence with observed ones. (C) 2000 Elsevier Science B.V. All rights reserved.
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