Hydrologic Change in Mountainous Tropical Watersheds: The Roles of Roads and Deforested Land Surfaces in Altering Watershed Function and Accelerating Soil Erosion

0000546詹贝鲁卡农村道路网的扩大和陡坡地耕作的加强对东南亚大陆主要河流系统的水文变化和沉积作用有重大贡献。 在这一地区的高地流域开展的国内和国际保护项目历来侧重于少数民族（山地部落）群体的农业实践。 虽然陡坡上的不当耕作技术肯定是造成某些地区严重下游影响的原因，但扩大农村公路网可能同样重要或更为重要。 为了促进对道路对区域水文影响的科学认识，必须在流域尺度上，在其他水文上重要的土地覆盖变化的背景下，对道路的影响进行研究。 这是真实的世界所有地区，温带或寒带。拟议的研究的目的是调查的作用，以及之间的相互作用，道路和非道路的土地表面在改变流域功能和加速土壤侵蚀的地区正在经历热带森林砍伐。 我们建议：（1）使用之前NSF支持的项目中收集的实地数据验证分布式水文-土壤-植被模型（DHSVM），该项目调查了93.7公顷的道路影响。在泰国北方的Pang Khum实验流域（PKEW），（2）继续实地测量PKEW的土壤-植被-大气传输（SVAT）过程和与道路相关的水文/侵蚀变量，（3）调查地下水流过程（即，通过道路棱镜拦截地下水流），以及（4）确定指数，使我们能够将我们的方法扩展到更大的集水区。 为了研究PKEW中测量的水文和泥沙通量，我们将耦合泥沙分离和路由方程与DHSVM中描述表面流的方程。 调整后的模型将帮助我们确定的来源，地表径流和输沙，并研究这些通量与PKEW重新分配，或从盆地输送。 最后，我们将使用该模型来量化过去50年来PKEW中道路的出现和农业在陡坡土地上的扩张所造成的流域影响。该项目联合了两组研究道路相关影响的研究人员：一组一直在热带地区工作;另一组在美国太平洋西北部。 虽然在泰国设置，这项研究将直接有助于在美国所有山区进行土地转换的道路相关的影响的研究。

0000546GiambellucaThe expansion of rural road networks and the intensification of cultivation on steeply sloped lands contributes significantly to hydrologic change and sedimentation in major river systems of mainland southeast Asia. Domestic and international conservation projects conducted in highland watersheds of this region have historically focused on the agricultural practices of ethnic minority (hill tribe) groups. While improper cultivation techniques on steep slopes are certainly responsible for serious downstream effects in some areas, expansion of the rural road network may be equally or more important. To advance scientific understanding of the impacts of roads on regional hydrology, they must be studied at the watershed scale, within the context of other hydrologically important land-cover changes. This is true for all regions of the world, temperate or frigid.The objective of the proposed study is to investigate the roles of, and the interaction between, roads and nonroad land surfaces in altering watershed functions and accelerating soil erosion in areas undergoing tropical deforestation. We propose to (1) validate the Distributed Hydrology-Soil-Vegetation Model (DHSVM) with field data collected during a prior NSF-supported project investigating road impacts in the 93.7-ha. Pang Khum Experiment Watershed (PKEW) in northern Thailand, (2) continue field measurement of soil-vegetation-atmosphere-transfer (SVAT) processes and road-related hydrologic/erosion variables in PKEW, (3) investigate the frequency of runoff generation on roads by subsurface flow processes (i.e., interception of subsurface flow by the road prism), and (4) identify indices that will allow us to extend our methodologies to larger catchments. To study the hydrologic and sediment fluxes measured in PKEW, we will couple sediment detachment and routing equations with equations describing surface flow in DHSVM. The adapted model will help us to determine the sources of overland flow and transported sediment, and to study where these fluxes are redistributed with PKEW, or transported from the basin. We will finally use the model to quantify watershed impacts resulting from the emergence of roads and the expansion of agriculture on steeply sloping lands within PKEW over the last 50 years.The project unites two groups of researchers who have been studying road-related impacts: one group has been working in the tropics; the other in the U.S. Pacific northwest. Although set in Thailand, this research will directly contribute to the study of road-related impacts in all mountainous areas of the United States undergoing land conversion.