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率，是流域对降水事件响应的重要决定因素。水流化学反过来又受到表征水文响应的时变流动路径的影响。尽管近年来在了解水流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，但不同简化假设对当前模型的影响尚未系统地探索。特别是，区域地下水位以上的地下暴雨带的动力学还没有得到充分的研究，尽管水汽带中的水在决定水流化学方面起着主要作用。土壤湿度的明确计算必须是集水区水化学反应充分量化的一部分。该研究的目标是建立一个定量和预测的基于物理的腐石岩-花岗岩流域水文响应模型，并探索地表地形和地下结构在确定流域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.