STREAM STRUCTURE ACROSS FIVE MOUNTAINOUS WATERSHEDS IN THE CONTINENTAL UNITED STATES
美国大陆五个山区集水区的河溪结构分析(英文)

Stream geometry and related measurements are the baseline information needed for ecological analysis of materials and energy movements within a watershed landscape.Using the United States Geological Surveys(USGS)hydrography database and a geographic information system(ARC/INFO),we examined and compared the distribution of streams,stream sections,total numbers,density,and riparian zones,in five mountainous watersheds in the continental United States:the Pacific Coastal Range,Cascades,Rockies,Appalachian Mountains,and Ozarks.Stream networks were found to be similar among the watersheds,with first order streams comprising up to 60% of the watersheds,The two watersheds in the eastern US had smaller stream length,basin relief,and higher stream density and section density than western watersheds.The amount of riparian area linearly increased with buffer width and did not account for larger amounts of the land area. Only seven to twelve percent of a total watershed area was included in riparian areas when a 60m buffer width was applied.Riparian zone distribution was related to watershed geomorphology.Emprirical models were developed to predict the proportions of stream,stream density,and changes in riparian areas with stream order within each watershed.Applications of these results in ecosystem analysis at watershed scales and riparian zone management are discussed.