Analysis of geomorphologic and hydrological characteristics in watershed saturated areas using topographic‐index threshold and geomorphology‐based runoff model

Abstract

Abstract:The objective of this paper is to investigate the variation of geomorphology and runoff characteristics in saturated areas under different partial contributing area (PCA) conditions. Geomorphologic information and hydrologic records from two mid-size watersheds in northern Taiwan were selected for analysis. The PCA ratio in the watershed during a storm was assumed equal to the ratio of the surface-flow volume to the direct runoff volume from measured hydrologic data. The extents of PCA regions were then determined by using a topographic-index threshold. Consequently, the geomorphologic factors in saturated and unsaturated areas could be calculated using a digital elevation model, and these factors could then be linked to a geomorphology-based IUH model for runoff simulation, which can consider both the surface-and subsurface-flow processes in saturated and unsaturated areas, respectively. The results show that geomorphologic characteristics in the saturated areas vary significantly with different PCA ratios especially for higher order streams. A large PCA ratio results in a sharp hydrograph because the quick surface flow dominates the runoff process, whereas the hydrologic response in a low PCA case is dominated by the delayed subsurface flow.

Separation of surface flow from subsurface flow in catchments using runoff coefficient

“…In Figure 9a, the SF values for the catchments calculated using Eq. 8 are compared with the values obtained by the GIUH method in the two catchments recorded by Chang and Lee (2008) (column 3, Table 6). The correlation coefficient was 0.98, which is very good.…”

“…10). To evaluate model fitness for this purpose, coefficient of efficiency (CE) and relative error in peak (REP) were calculated (Chang and Lee 2008): is observed peak discharge.…”

“…Recorded SF, peak SF and SSF estimates obtained using the GIUH method, for the Heng-Chi and San-Hsia catchments in northern Taiwan (source:Chang and Lee 2008) …”

Índices topográficos aplicados à modelagem agrícola e ambiental

“…Áreas em branco representariam áreas com maior risco, devido à menor capacidade de armazenamento de água pelos solos, sendo então recomendadas para culturas resistentes a secas. Os limites sugeridos para as classes da figura 3 poderiam ser validados com o acompanhamento da análise da umidade do solo após eventos de chuva e durante estiagens, conforme se verifica nos trabalhos de CHAPLOT & WALTER (2003), CHANG & LEE (2008) e DETTY & MCGUIRE (2010).…”

Prediction of surface and subsurface flow in catchments using the GIUH

“…50%). Chang and Lee () studied the influence of geomorphological features as well as run‐off on the saturated zones of catchment hillslopes in the partial contributing area conditions. The dynamic interaction between the saturated–unsaturated subsurface flow and surface flow has been examined by Freeze and Harlan () and Freeze (, , b) through numerical simulation.…”