推求地面径流单位线的Free Search算法

地面径流单位线在水文计算和水文预报工作中应用十分普遍,但当净雨时段较多时,传统的单位线推求方法存在工作量大、效率不高、过分依赖专业经验、计算过程复杂、模拟结果可能出现负值等问题。为此,本文引入源于动物群体迁移行为的自由搜索(Free Search,FS)算法,将FS单个动物每步探查行走的位置向量作为一条初始单位线,在FS算法迭代过程中再将所有的初始单位线转化为符合定义的单位线,从而利用动物群体的迁移行为推求出最优单位线。该方法的优点是概念清晰,操作简便,能够直接给出单位线的各时段流量值。三个典型实例模拟结果表明:利用FS推求单位线时,寻优一次即可得到满意结果,所得单位线不需要修正,并且能够有效克服锯齿现象,对地面径流量的模拟精度也较高。

Estimating Surface Runoff Unit Hydrograph by Free Search

Unit hydrograph of surface runoff is widely used in hydrological calculation and forecast. However, when the net rainfall with multi-intervals appear, some advantages exist in the traditional approach of unit hydrograph method such as heavy, inefficient, complex, and the simulation results may be negative. In this paper, Free Search (FS), derived from the animal group migration behavior, was used as a method for estimating surface runoff unit hydrograph. The position vector of each exploratory step for the individual animal of FS was ascertained as an initial unit hydrograph. All the initial unit hydrographs were converted into the standard unit hydrographs in the iterative process of FS, and the optimal unit hydrograph was eventually ascertained from the animal group migration. FS exhibits the advantages of the clear concept and simple operation, and the flow discharge of each time interval can be given directly. The simulation results for three cases show that the satisfactory results could be achieved by FS for optimizing the unit hydrograph once; the unit hydrograph without negative and need not to be fixed; the fluctuation in the results was effectively avoided; and surface runoff simulation exhibits relatively high precision.