流域生态水文系统的动力学特性初步分析

Analysis of the Dynamics of Ecohydrological System in the River Basin

流域的生态和水文等各种过程中进行着水、能量、碳等的流动和交换,构成了一个多过程耦合的动力学系统。建立概念性的流域水文模型,对流域上的产汇流等主要水文过程进行模拟,引入植被覆盖度演化的动力学方程,把生态过程与水文过程相耦合,模拟流域内生态水文过程,分析了流域生态水文系统的动力学特性。模拟结果显示,在不同年降雨量条件下,流域的植被覆盖度会从相同初始值演化到不同的覆盖度水平稳定值,年降雨量越大,植被覆盖度趋向于越大的稳定值。在不同的植被覆盖度初始值下,在相同降雨条件下植被覆盖度会演化到不同的覆盖度水平,系统存在多重定态。遇到连续枯水年后,高植被覆盖度的状态会退化到低植被覆盖度的状态。模拟得到的动力学系统性质决定于植被动力学方程。植被覆盖度动力学方程的完善是今后研究工作的重要内容。

Water, energy, carbon and others /low and exchange in the ecological and hydrological processes in the river basin consist of a dynamical system of multi-processes coupling. A conceptual wa- tershed hydrological model is built up to model the main hydrological processes, such as runoff generation and runoff routing in the river basin. The vegetation dynamical equation is introduced into the model to couple the ecological process and hydrological process, and the ecohydrological processes are simulated in the river basin. The dynamics of the ecohydrological system of the river basin is analyzed. The results show that the vegetation coverage will evolve from the same initial values to different stable states of the vegetation coverage in the condition of different annual precipitation and the vegetation coverage will e- volve to the larger state with the larger annual precipitation. From different initial values of vegetation coverage, the vegetation coverage will evolve to different vegetation coverage with the same precipitation. The system has multiple stable states. The state of high vegetation coverage will degenerate to the state of lower vegetation coverage after continuous dry years. The characteristics of the dynamical system from the simulation are determined by vegetation dynamical equation. The perfecting of the vegetation dynamical equation is the key research topic in future.