Land use/cover change and its effects on hydrologic processes are becoming an important aspect of global change research.In order to understand the effects of deforestation on hydrologic processes in theDaxing'anling area

a five-stage land use/cover date base in the Nuomin River basin since 1954was established based on remote sensing imagery data and topographic map.With GIS spatial analysis tools

the paperanalyzed the land use/cover change characteristics and its effects on hydrologic process.Results indicatedthat land use changed prominently in the Nuomin River basin during the past five decades.Forest and grassland decreased by 1 940.10and 748.99km2

respectively

and in contrast

cropland increased by 2 741.7km2.Since the nature forest protection project came into force in the Daxing'anling area in 1998

woodlandreduction and farmland reclamation have showed a declined trend.Land use/cover change had effects on annual runoff and runoff increased during the late land use period with decreased forest and more cropland

andthe impact of land use/cover change on runoff was strengthened in response to increased rainfall.Besides

the effects of land use/cover change on runoff production were characterized by seasonal fluctuation.