基于潜水渗流模型解反演灌区灌溉回渗强度

在沟渠纵横的灌区, 灌溉回渗包括田间下渗与沟渠侧渗, 依据地下水水位变动分项计算下渗与侧渗困难。文章利用含田间灌溉下渗作用的灌渠附近潜水非稳定流模型, 通过 Laplace 变换求出模型解析解。根据模型解建立基于潜水水位动态数据反演田间灌溉下渗强度的算式, 并结合 Darcy 定律推导出反演沟渠侧渗强度的算式。以淮北平原某干渠附近潜水水位动态为实例反演上述计算过程。结果表明, 在 48 h 的计算期内, 沟渠侧渗对潜水位变动的贡献比例, 从初期的 4.3% 迅速上升到末期的 62.8%。该研究提出的下渗强度反演算式所需数据比较容易获得, 便于实际应用。

In irrigation areas with vertical and horizontal ditches, irrigation infiltration includes field infiltration and ditch lateral infiltration, and it is difficult to calculate infiltration and lateral infiltration according to the change of groundwater level. In this paper, the unsteady flow model of phreatic water near the irrigation canal with field irrigation infiltration is adopted, and the analytical solution of the model is obtained by Laplace transform. According to the model solution, the formula for inverting the infiltration intensity of field irrigation based on the dynamic data of phreatic water level is established, and the formula for inverting the lateral infiltration intensity of ditches is derived in conjunction with Darcy's law. Taking the phreatic water level dynamics near a main canal in Huaibei Plain as an example, the above calculation process was inverted. The results show that during the calculation period of 48 hours, the contribution ratio of lateral infiltration of ditches to the change of phreatic water level rises rapidly from 4.3% in the initial stage to 62.8% in the final stage. The formula for inverting the infiltration intensity proposed in the paper requires relatively accessible data and is convenient for practical application.