坡面薄层水流流速的测量对研究地表水文过程具有重要意义.电解质脉冲法将边界条件用脉冲函数近似得到解析解,进而估算流速,引起误差.本研究在脉冲法的基础上改进,在测量系统中增加一组探针用于测量实际的边界函数.利用测得的边界条件数据,计算出模型边界条件的参数,进而将系统的真实边界条件的解与实测数据拟合,用最小二乘法计算流速.结果表明:两种真实边界条件法估算的流速没有显著差别,与流量法测量结果也一致,在短距离时真实边界条件法比脉冲法有较高的精度.由此说明,采用真实边界条件法和系统测量流速是可行的.%The measurement of shallow water flow velocity is significant to hydrological process. A pulse function was used as boundary condition for the analytical solution so as to estimate shallow water flow velocity with relatively high errors. In this study, an additional sensor was added at the location close to the salt injection to register the actual boundary function. The measured boundary condition data were used to estimate the parameters of the boundary condition. Then the shallow water flow velocity was determined by using the least square method. The experimental results indicated that the velocities computed by the two realistic boundary condition methods showed no significant difference, and they agreed also with those measured by the volumetric method. Especially, at short distance, the realistic boundary condition methods had higher accuracy than the pulse method. Thus the realistic boundary condition method and system could be a feasible way to measure water flow velocity.
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