Based on the technology of remote sensing and geographic information systems

a karst sinkholebased semidistributed hydrological model was applied to study the impacts of various land use scenarios on runoff and hydrological processes within different years in the Houzhai River Basin located in Puding County

Guizhou Province. The results show that compared with the original land use type

forest and paddy field reduce substantially the runoff and the bare rock scenario increases the runoff slightly but not significantly.The runoff discharge followed the order as bare rock>forest land>paddy field under the extreme scenarios.An optimal land use scenario was designed according to the characters of land use with differential terrains.The simulated runoff discharges under the optimal scenario decreased

comparing to the original land use scheme. It seemed that the optimal scenario improves the efficiency of water resource utilization. Under the scenarios of the extreme land use and the optimal land use

runoff discharges were affected by land use to a greater degree in summer and autumn and to a less degree in winter and spring. The karst hydrological processes response to land use strongly in dry years

moderately in normal years

and weakly in wet years.