管道流模型参数敏感性分析及其在许家沟泉域的应用

在岩溶含水系统中，作为主要排水通道的管道对泉流量动态具有一定的控制作用，而管道特征参数对流量变化亦有影响。为确定管道各参数的影响，前人以管道发育的岩溶水系统为研究对象，进行了短时间序列泉流量响应的分析探讨，而对岩溶管道不十分发育的岩溶水系统的研究较薄弱。为此，本研究结合北方岩溶水系统的发育特征，借助CFP管道流模型对管道各参数对岩溶系统流量和流态的影响程度及各参数的敏感性进行了分析，而后基于河南鹤壁许家沟泉域岩溶水文地质特征构建了泉域的MODFLOW-CFP模型，对泉域岩溶地下水渗流进行了模拟，并对不同降水保证率下的泉流量进行了预测。结果表明:管道流量与管壁渗透系数、管道坡度和管径呈正相关，而随弯曲度和埋深的增加管道流量呈先增大后减小的趋势。管壁粗糙度对流量的影响较小，且呈现出一定的波动性，尤其是当管壁粗糙度较小时，波动比较明显。经敏感性分析发现，管壁渗透系数和埋深的敏感性最高，其次为弯曲度和管道坡度，而管道直径和管壁粗糙度敏感性最低。许家沟泉域在25%降水保证率下，年最大泉流量为0.45 m3/s，平均泉流量为0.36 m3/s；在75%降水保证率下，年最大泉流量为0.41 m3/s，平均泉流量为0.31 m3/s，与实际情况吻合。该法可为我国北方岩溶区水资源评价及泉域水资源开发保护提供借鉴。

A sensitivity analysis of conduit flow model parameters and its application to the catch area of the Xujiagou spring

In the karst aquifer systems, the pipelines as the main drainage channels have a certain control effect on the spring flow dynamics, and the pipeline characteristic parameters also have an impact on the flow variation. In order to determine the influence of various parameters of the pipelines, the karst water systems developed by the pipelines were studied by predecessors, and the response of the spring discharge of short-time series was analyzed and discussed. However, the research on the karst water systems which were not very developed by the karst pipeline is relatively weak. For this reason, this study combines the development characteristics of karst water systems in North China, analyses the influence degree and sensitivity of various parameters of pipeline on the flow rate and flow pattern of karst systems by means of the CFP pipeline flow model, and constructs the MODFLOW-CFP model of the spring basin based on the karst hydrogeological characteristics of the Xujiagou spring basin in Hebi of Henan. The seepage of karst groundwater is simulated and the spring discharge under different rainfall guarantee rates is predicted. The results show that the pipe flow rate is positively correlated with the coefficient of permeability of the pipe wall, the slope and diameter of the pipe, while the pipe flow rate increases first and then decreases with the increasing bending and burial depth. The influence of the pipe wall roughness on flow rate is small and shows certain fluctuation, especially when the pipe wall roughness is small, the fluctuation is obvious. Sensitivity analyses show that the sensitivity of the coefficient of permeability and burial depth of pipe wall is the highest, followed by the curvature and slope of pipe, while the sensitivity of diameter and roughness of pipe wall is the lowest. Under the rainfall guarantee rate of 25%, the annual maximum spring discharge is 0.45 m3/s and the average spring discharge is 0.36 m3/s. Under the rainfall guarantee rate of 75%, the annual maximum spring discharge is 0.41 m3/s and the average spring discharge is 0.31 m3/s, which are consistent with those of the actual situation. This method can provide reference for water resources evaluation, development and protection in karst areas of northern China.