Effects of Spatial Scales on Runoff / Sediment Transport in Mountain Catchments (1) - A Review of Field Observations on Catchment Area and Properties

Abstract

　Examining the patterns of spatial variability of runoff and sediment transport is necessary for understanding hydrologic and geomorphic processes in watersheds. Knowledge of water and sediment transport behaviors in various catchment areas can improve the process-based representation of numerical models. We reviewed the relations between drainage areas and various properties of runoff and sediment transport comprehensively, particularly addressing spatial-scale dependence and spatial heterogeneity. Results show that patterns of increases and decrease of water and sediment amounts occurred relative to the catchment area, although other properties showed no distinctive relation to catchment areas, partly because of a lack of measured data. Most earlier studies specifically examined either spatial-scale dependence or spatial heterogeneity. Properties such as peak specific discharge showing clear spatial-scale dependence should be controlled by mechanisms that change with the spatial scale. Properties such as specific discharge during base flow showed spatial heterogeneity. Results suggest that mechanisms controlling base flow did not change much with the spatial scale for the measured ranges of catchment areas. Heterogeneous properties of landscapes exerted strong effects on those properties.