陕西省泾惠渠灌区地下水污染与人体健康风险评价

通常井内的地下水流速是由单井示踪试验或Aqua Vision流速流向仪测定得来，用以计算含水层中的地下水流速。由于表皮结构的影响，导致井筒附近的地下水流场发生变化，引起井筒内的流速与含水层中的流速存在偏差。为了探究表皮效应对井筒内地下水流速的影响，利用COMSOL Multiphysics软件，建立考虑表皮效应的地下水流数值模型，系统分析表皮厚度以及渗透系数对井筒中地下水流速的影响机制，根据模拟结果进一步评估利用井筒内地下水流速换算含水层地下水达西流速已有经验公式的可靠性。结果表明：(1)井筒附近表皮区域渗透系数越大，井筒内的地下水流速越大，且利用经验公式计算的地下水达西流速相对误差均小于0.23%，具有较高可靠性；(2)表皮区域渗透系数小于含水层渗透系数时，随着表皮厚度增大，井筒内地下水流速越小，经验公式计算结果的相对误差呈现增大趋势；(3)表皮区域渗透系数大于含水层渗透系数时，随着表皮厚度增大，井筒内地下水流速增大，计算结果相对误差总体上呈现减小的趋势，但其误差波动性较大，表明在该条件下经验公式计算的稳定性较差。结果显示表皮结构对井筒内地下水流速影响较大，在实际应用中要关注表皮结构的影响。

Groundwater contamination and human health risk assessment in Jinghui irrigation district,Shaanxi Province

Groundwater flow velocity in wellbore is usually measured by single-well tracking tests or Aqua Vision flow velocity and direction meters to calculate the groundwater flow velocity in the aquifer. Due to the impact of the skin structure, the groundwater flow field near the wellbore changes, causing a difference between the flow velocity in the wellbore and that in the aquifer. In order to investigate the influence of the skin effect on the groundwater flow velocity in the wellbore, a numerical model of groundwater flow that considers the skin effect was established using the COMSOL Multiphysics software. On this basis, the mechanisms by which the skin thickness and hydraulic conductivity affect the groundwater flow velocity in the wellbore was systematically analyzed and the reliability of the existing empirical formula that converts the groundwater flow velocity in the wellbore into the Darcy velocity in the aquifer was further assessed based on the simulation results. Key finding are as follows: (1) The larger the hydraulic conductivity of the skin area near the wellbore, the greater the groundwater flow velocity in the wellbore, and the relative error of the groundwater flow velocity calculated by the empirical formula is less than 0.23%, showing high reliability. (2) When the hydraulic conductivity of the skin area is smaller than that of the aquifer, the groundwater flow velocity in the wellbore decreases as the skin thickness increases, and the relative error of the empirical formula calculation shows an increasing trend. (3) When the hydraulic conductivity of the skin area is larger than that of the aquifer, the groundwater flow velocity in the wellbore increases as the skin thickness increases, and the relative error of calculation shows a decrease trend in general, but its error volatility is large, indicating that the stability of the empirical formula calculation under this condition is poor. In conclusion, the skin structure has a great influence on the water flow rate inside the wellbore, and the influence of skin structure should be concerned in practical projects.