Hydrological response of subsurface stormflow through soil matrix and macropores on forested hillslopes
Project manager: Kyongha Kim, Bernd Huwe Grant: IRTG 1565 WP II TERRECO - Complex Terrain and Ecological Heterogeneity - Evaluating ecosystem services in production versus water yield and water quality in mountainous landscapes
This study has been conducted to clarify runoff production processes in forested catchment through hydrograph separation, using a three-component mixing model based on the End Member Mixing Analysis (EMMA) model. The study area is located in the coniferous-forested experimental catchment, Gwangneung Gyeonggido near Seoul, Korea (N 37 45', E 127 09'). This catchment is covered by Pinus koraiensis and Abies holophylla planted at stocking rate of 3,000 trees ha-1 in 1976. Thinning and pruning were carried out two times in the spring of 1996 and 2004 respectively. We monitored eight successive events during the periods from June 15 to September 15, 2005. Throughfall, soil water and groundwater were sampled by the bulk sampler after each event. Stream water was sampled every 2-hour through ISCO automatic sampler for 48 hours. The geochemical tracers were determined in the result of principal components analysis. The concentrations of SO42-+ for stream water almost were distributed within the triangle diagram of the end members; throughfall, soil water and ground water. Average contributions of throughfall, soil water and groundwater on producing stream flow for 6 events were 17%, 25% and 58% respectively. The antecedent precipitation index (API) plays an important role in determining which end member prevails during events. It was found that the low API event produced more ground water compared with the high API event. On the other hand, rain water indicated the opposite. It may be caused by overland flow in areas where soil water content is near saturation. API controls runoff producing mechanism whether surface or subsurface flow prevails. Current efforts are directed at examining the significance of the results for estimating water balance of the Haean catchment in Yanggu County.