Abstract
The infiltration-runoff processes in source areas provides fundamental information for hydro-geomorphological studies, as well as environmental management of a watershed. This study presents the water movement from forest-covered slopes with layered soil to a stream-initiation point in a valley-head. The water movement in the storm events is discussed, based on both capillary potential data recorded at three points in a head hollow and runoff data observed at the base of the catchment. The BC horizon is thick in the upper head hollow, but thin in the lower one. And the BC horizon is also thick in the area three direction from the upper head hollow. One is along the talweg but two is unrelated to microtopography. AB horizon is thick in the lowest portion of the lower head hollow. In the area most of BC horizon is eroded and buried by AB horizon, and this structure is connected to the pipe flow and the crack of rock.
The runoff from pipe or crack is 78 of the total runoff in the observation period. Runoff starting condition is estimated by the M-API(API from an hour precipitation data).
The flow path of infiltration-runoff processes is divided three ways. 1: flow only in A and AB horizon in infiltration-runoff processes, 2: flow in BC horizon in infiltration-runoff processes, but not in fractured rock, 3: flow in the fractured rock. The partial contributing area expands in the big storm and flow only in A and AB horizon exceeds the other flow. But in the summer dry season, though not small rainfall supplied to the catchment area, very little runoff occurred and the contributing area is very small.
