Runoff and Channel Initiation in Humid Landscapes

了解是什么控制了河谷网络中沟头的位置，对于预测排水密度以及景观对气候、土地利用和基准面变化的响应至关重要。最近对半干旱到湿润地形的水道头位置的研究表明，对于一个给定的地区，水道头逐渐向下坡延伸，因此在较温和的山谷中排水面积更大。关于河道起裂的理论很少，而且由于缺乏对径流和侵蚀过程的详细现场观测，而这些观测可用于激发和测试基于物理的方程，因此受到严重限制。我们建议在平缓和陡峭的无沟渠山谷中进行实地试验，监测自然和人工暴雨期间的径流和侵蚀。我们将使用这些实验的结果来测试和扩展径流生成的可用模型，并将这些模型与侵蚀理论相结合，以预测沟道头的位置。工作将在加利福尼亚州和俄勒冈州进行，我们在那里有积极的水文和地貌过程研究项目。这里提出的工作也是一个重要的垫脚石，以形成一个理论的景观演变的山谷发展。

Understanding what controls the location of the channel head in a valley network is crucial to predicting drainage density, and the response of landscapes to changes in climate, landuse, and base level. Recent studies of channel head locations in semi-arid to humid landscapes have suggested that for a given area, channel heads are found progressively farther downslope, hence draining a larger area, in gentler valleys. Theories for channel initiation are few and are severely limited by a lack of detailed field observations on runoff and erosion processes that can be used to motivate and test physics-based equations. We propose to conduct field experiments by monitoring runoff and erosion during natural and artificial rainstorms in gentle and steep gradient unchanneled valleys. We will use results from these experiments to test and extend available models for runoff generation and we will couple with these models with erosion theories to predict channel head locations. Work will be carried out at sites in California and Oregon where we have active research field programs in hydrologic and geomorphic processes. The work proposed here is also an essential stepping stone toward formulating a theory for landscape evolution by valley development.