Three pairs of small, fourth- to sixth-order catchments (approximately 5–80 km²), draining the margin of the Darjeeling Himalayas into the piedmont, were selected for a comparison of the land-use impact on the morphology and sedimentology of their stream channels. Each pair experienced similar annual rainfall and comprised similar metamorphic bedrock, steep topography, and brown soils; the members of each pair contrast with respect to their land-use structure as they comprise large forest cover (forest >90%) and a significant contribution of agricultural land with tea plantations (forest <63%), respectively. A set of rainfall, cross-sectional, and sediment data were collected for the characterization of the stream channels. The obtained results revealed that, under extreme rainfall and high denudation rates as well as frequent flash floods, the geomorphic response to land-use changes involving agricultural expansion at the expense of forest cover was less pronounced in the mountain channels than in the piedmont. Significant differences between the studied pairs of mountain streams draining forested and agricultural catchments were observed only at bankfull width and baseflow depth in fourth-order streams and baseflow depth in fifth-order streams. Local environmental factors such as bedrock channel boundaries, steep topography, high material supply to river networks, and selective sediment mobilization during extreme rainfall and floods override the effects of land use and exert dominant control over stream channels in mountain catchments. However, the effects of agricultural activity in mountains are propagated downstream. In the agricultural catchment in the piedmont, a local rapid decrease in river slope and an increase in water infiltration into alluvia facilitates the deposition of eroded material. In addition, the stream in the agricultural catchment exhibited a rise in the riverbed with the expansion of a braided channel over a dozen kilometers below the Himalayan front in the piedmont, while the streams in the forested catchment revealed a distinct tendency towards incision. The present-day channel morphologies and sediment patterns observed in forested catchments are most likely similar to those that existed in the studied rivers prior to the development of tea plantations and settlements in the mid-19th century.

三对小型四到六级流域（约5–80 km ²），将大吉岭喜马拉雅山脉的边缘排入山麓，以比较土地利用对其河流河道的形态和沉积学的影响。每对年降水量相似，包括类似的变质基岩，陡峭的地形和褐色的土壤。每对成员的土地利用结构形成鲜明对比，因为它们包括大片的森林覆盖率（森林> 90％）和农业用地占很大比例的茶园（森林<63％）。收集了一组降雨，横断面和泥沙数据，以表征流道。获得的结果表明，在极端降雨和高剥蚀率以及频繁的山洪暴发的情况下，山区渠道对山地通道对土地利用变化的地貌反应（包括以森林覆盖为代价的农业扩张）反应不明显。仅在四阶河段的河岸宽和基流深度以及五阶河段的基流深度，才观察到研究的成对的流向森林和农业集水区的山间流之间存在显着差异。当地环境因素（例如基岩河道边界，陡峭的地形，向河网的大量物质供应以及极端降雨和洪水期间的选择性泥沙动员）超越了土地利用的影响，并在山区流域控制了河道。但是，山区农业活动的影响向下游传播。在山麓的农业流域，河流坡度的局部迅速下降和渗入水的水渗入增加，促进了侵蚀物质的沉积。此外，农业流域的溪流在河床中呈上升趋势，在山前的喜马拉雅山前线下方十几公里处，一条辫状河道扩展了，而森林流域的溪流显示出明显的切开趋势。在森林流域中观察到的当今河道形态和沉积物模式很可能类似于19世纪中叶茶园和定居点发展之前研究过的河流中存在的河道形态和沉积物模式。农业集水区的溪流在河床中呈上升趋势，在山麓的喜马拉雅山下，辫状河道扩展了十几公里，而森林集水区的溪流显示出明显的切开趋势。在森林流域中观察到的当今河道形态和沉积物模式很可能类似于19世纪中叶茶园和定居点发展之前研究过的河流中存在的河道形态和沉积物模式。农业集水区的溪流在河床中呈上升趋势，在山麓的喜马拉雅山下，辫状河道扩展了十几公里，而森林集水区的溪流显示出明显的切开趋势。在森林流域中观察到的当今河道形态和沉积物模式很可能类似于19世纪中叶茶园和定居点发展之前研究过的河流中存在的河道形态和沉积物模式。