抚仙湖集水域径流过程的观测与模拟

Observation and Modeling of Surface and Subsurface Runoffs for Fuxianhu Lake Catchment

抚仙湖集水域的径流过程包括河道径流、坡面散流和地下径流,各径流间发生水量交换,且同时向湖泊输送污染物。针对这一特点,提出以整体水文过程思路建立径流及物质输移模型,以完整统一的模型模拟整个集水域的径流过程及污染物入湖路径。模拟方法考虑各径流之间的水量交换,能定量区分各径流量及各径流分别向湖泊输送的物质数量,可望深层次地揭示湖泊集水域的径流系统及物质输移路径。设计了相应的野外观测方案,对各径流及降雨量作同步连续观测。观测数据显示,该集水域降雨强度分布不均匀;河道径流量与降雨相关性强,表现出暴涨暴落的特点,反映了山区河道径流特征;北岸农田区地下水埋深较浅,表层土体松散,接受良好的降雨补给。这些成果为观测方案的进一步细化和模型建设提供了可靠的依据。

Fuxianhu lake is located in Yunnan province, southwest of China. It is a deep freshwater lake with a water surface area of 212 km^2 and a catchment area of 651 km^2. Within the catchment, there exist stream flow, surface runoff and subsurface runoff, which are major sources of incoming water of the lake. These water flows also bring catchment-generated pollutants to the lake. Hydrological processes are complicated in terms of the flow pattern and water exchange between runoffs. In order to accommodate these characteristics and complexities, a hydrological model is proposed based on the concept of “integrated hydrological process”. The model takes into account the dynamic water exchange between runoffs and is expected to quantitatively distinguish different types of runoff, and associated pollutants transport. Accordingly, a field observation scheme for rainfall, stream flow and subsurface flow is implemented. Observation data show that rainfall intensity varies significantly across the catchment. Stream flow rate responds rapidly to rainfall showing a typical hydraulic pattern of mountainous streams. Groundwater level is as shallow as less than 2 m deep in some areas. Groundwater level fluctuates in response to rainfall demonstrating a vertical rainfall recharge data give valuable guidance to further refine the observation support for model construction and validation.