Basin Hydrology

Abstract

A drainage basin is a most natural hydrologic unit. Guided by topography, a drainage divide separates the water that flows into and away from a catchment. A basin integrates the disparate hydrologic activities occurring spatially within its domain. Streamflow characteristics are a manifestation of the combined results of various hydrologic processes occurring in a basin. Basin water balance investigation yields information on how much water is gained and lost in quantitative terms. Basin Outflow GenerationThe timing and amount of outflow produced from a basin are governed by (1) net amount of runoff generated from various water sources, (2) amalgamation of runoff in the flow delivery network, which comprises the pathways both on slopes and in channels, and (3) retardation and loss of flow en route to the basin outlet due to storage, including storages in channels, wetlands and in lakes along the flow route. Some conditions complicate outflow generation from permafrost basins. Owing to freeze-thaw of the active layer, not only does the amount of basin storage, but the capacity of basin storage also changes in the course of the flow season. In addition, the configuration of flow paths is altered continually during snowmelt when surface and subsurface flow routes change with snow position and active layer thaw. Snow and ice obstruction in river channels further affects the delivery of flow.Small basins (areas of 10 0 -10 2 km 2 ) provide appropriate examples for the following discussion as they offer sufficiently fine spatial resolution to permit examination of how the physical processes operate, and most investigations have been conducted at such a basin scale.M.-k. Woo, Permafrost Hydrology,