Implications of Catchment Structure for Time-Varying Hydrological and Hydrochemical Response in a Forested Headwater Catchment

流域结构，包括地表地形和地下渗透性，是流域对降水事件响应的重要决定因素。溪水化学反过来又受到表征水文响应的时变流动路径的影响。尽管近年来在理解流动路径和水的化学成分如何反映这些路径方面取得了很大进展，但目前模型所依据的不同简化假设的影响还没有得到系统的探讨。特别是，尽管包气带中的水在决定溪流水化学方面起着重要作用，但区域地下水位以上的地下风暴流带的动态还没有得到充分的研究。对土壤水分的明确核算必须是充分量化集水区水化学反应的一部分。这项研究的目的是建立腐泥岩-花岗岩集水区水文响应的定量和预测物理模型，并探索地表地形和地下结构在确定集水区水化学响应中的重要性。

Catchment structure, both surface topography and subsurface permeability, is an important determinant of catchment response to precipitation events. Stream water chemistry is in turn influenced by time-varying flow paths that characterize hydrological response. Although much progress has been made in recent years in understanding the flow paths and how chemical composition of waters reflect these paths, the impact of different simplifying assumptions underlying current models have not been explored systematically. In particular, the dynamics of a subsurface stormflow zone above a regional water table have not been addressed fully even though water in the vadose zone plays a major role in determining stream water chemistry. An explicit accounting of soil moisture must be part of an adequate quantification of catchment hydrochemical response. The goal of the study is to develop a quantitative and predictive physically-based model of the hydrological response of a saprolite-granite catchment and to explore the importance of surface topography and subsurface structure in determining catchment hydrochemical response.