Numerical calculation of secondary discharge peak from a small watershed using a physically based watershed scale infiltration simulation
Autor: | Rieko Urakawa, Kikuo Haibara, Yoshiki Shinomiya, Hiroto Toda, Katsushige Shiraki |
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Rok vydání: | 2007 |
Předmět: |
Topsoil
Watershed Computer simulation Watershed area Forestry Hydrograph Soil science 04 agricultural and veterinary sciences 010501 environmental sciences 01 natural sciences Infiltration (hydrology) 040103 agronomy & agriculture 0401 agriculture forestry and fisheries Environmental science Richards equation Surface runoff 0105 earth and related environmental sciences |
Zdroj: | Journal of Forest Research. 12:201-208 |
ISSN: | 1610-7403 1341-6979 |
Popis: | Numerical infiltration simulations were performed to reproduce secondary discharge peaks in a mountainous forest watershed (watershed area, 1.89 ha; average topsoil depth, 2.61 m; and bedrock geology, Mesozoic–Paleozoic) using a simplified physically based three-dimensional saturated and unsaturated water-flow model based on Richards’ equation. We were able to calculate the quick discharge during rain and a secondary discharge peak at the watershed simultaneously, using observed topographical information, the topsoil depth distribution, and soil hydraulic characteristics, and by dividing the watershed by 2.5 m horizontally and ten cells vertically. Although the calculated hydrograph did not agree entirely with the observed hydrograph, we conclude that the characteristics of the observed hydrograph were explained with better accuracy using the smaller soil porosity patterns than using the observed patterns. We verified that the simulation method based on Richards’ equation was effective to analyze the rainfall-runoff processes toward the intended watershed. Computational comparisons clarified that lower soil porosity quickens the timing of secondary discharge peaks and increases their volume. Additional examinations, such as the distribution of soil hydraulic characteristics and the actual condition of Hortonian overland flow, are necessary to simulate rainfall-runoff processes precisely at the intended watershed. |
Databáze: | OpenAIRE |
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