丘陵-平原-湿地复合区降雨径流数值模型

针对丘陵-平原-湿地复合地区降雨径流数值模型较少、而已构建的模型对水文要素空间分布和湿地区水流运动又反映不足,采用格子玻尔兹曼法和有限元法构建丘陵-平原-湿地复合区降雨径流数值模型。在模型构建过程中将复合区分为地势起伏较大的上游丘陵区和下游地势变化较小的平原湿地区。上游丘陵区降雨采用距离平方倒数法计算降雨空间分布、采用格子玻尔兹曼法建立非饱和区土壤水运动模型、利用达西公式建立饱和区水流运动模型、利用格子玻尔兹曼法构建汇流数值模型,进而构建了上游区的降雨径流数值模型。平原湿地区采用基于有限元四边形单元构建了水流运动数值模型。平原湿地区入口边界采用上游区降雨径流数值输出的流量过程,平原湿地区出口边界采用基于格子玻尔兹曼法的汇流模型计算的水位过程。四边形单元有限元求解水流运动方程实现了上、下游区的无缝连接,模型使用比较方便。以挠力河流域为研究对象进行了降雨径流和平坦区水流运动模拟研究,模拟结果良好,说明模型较为可靠。

Numerical Model of Rainfall Runoff in Hills-Plain-Wetland Compound Area

There are few numerical models on rainfall runoff in hills-plain-wetland compound area, and the existing models can not definitely reflect the characteristics of hydrological elements spatial distribution and hydrological cycle in wetland. A numerical model on rainfall runoff was constructed in hills-plain-wetland compound area by using lattice Boltzmann method (LBM) and finite element method. When constructing the model, the compound area was divided into upstream hilly region with great topographic relief and downstream plain wetland with little topographic relief. In the upstream hilly region, spatial distribution of rainfall was calculated with the inverse distance method, soil motion model in unsaturated zone was constructed with LBM, water flow model in saturated zone was constructed with Darcy formula, numerical model of runoff was constructed with LBM, and then the numerical model of upstream rainfall runoff was constructed. Numerical model of water flow on plain wetland was constructed by using the finite element method with quadrilateral element. The entry water level boundary of plain wetland used the numerical output water level process of rainfall runoff in upper reaches, and export water level in plain wetland was achieved by calculating the export water process of watershed based on the numerical model constructed with LBM. The flow motion equation was solved with quadrilateral finite element method, which realized the seamless connection of the upstream area and the downstream area, and made the application of the model more convenient. Rainfall runoff and flow in plain area was simulated, with the Naoli river watershed as an example, and the simulation result was good, which means that the model is reliable.