des Tombe Bas F, Bakker Mark, Schaars Frans, van der Made Kees-Jan
Water Resources Engineering Section, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, Netherlands.
Artesia, Schoonhoven, Netherlands.
Ground Water. 2018 Mar;56(2):288-299. doi: 10.1111/gwat.12581. Epub 2017 Aug 23.
An approach is presented to determine the seasonal variations in travel time in a bank filtration system using a passive heat tracer test. The temperature in the aquifer varies seasonally because of temperature variations of the infiltrating surface water and at the soil surface. Temperature was measured with distributed temperature sensing along fiber optic cables that were inserted vertically into the aquifer with direct push equipment. The approach was applied to a bank filtration system consisting of a sequence of alternating, elongated recharge basins and rows of recovery wells. A SEAWAT model was developed to simulate coupled flow and heat transport. The model of a two-dimensional vertical cross section is able to simulate the temperature of the water at the well and the measured vertical temperature profiles reasonably well. MODPATH was used to compute flowpaths and the travel time distribution. At the study site, temporal variation of the pumping discharge was the dominant factor influencing the travel time distribution. For an equivalent system with a constant pumping rate, variations in the travel time distribution are caused by variations in the temperature-dependent viscosity. As a result, travel times increase in the winter, when a larger fraction of the water travels through the warmer, lower part of the aquifer, and decrease in the summer, when the upper part of the aquifer is warmer.
本文提出了一种利用被动热示踪试验来确定岸边渗滤系统中旅行时间季节性变化的方法。由于渗入地表水和土壤表面的温度变化，含水层中的温度会随季节变化。通过沿垂直插入含水层的光纤电缆使用分布式温度传感来测量温度，该电缆是用直接推进设备插入的。该方法应用于一个由一系列交替排列的细长补给池和多排回灌井组成的岸边渗滤系统。开发了一个SEAWAT模型来模拟耦合水流和热传输。二维垂直横截面模型能够较好地模拟井中水温以及实测的垂直温度剖面。利用MODPATH计算水流路径和旅行时间分布。在研究地点，抽水流量的时间变化是影响旅行时间分布的主要因素。对于一个抽水速率恒定的等效系统，旅行时间分布的变化是由与温度相关的粘度变化引起的。因此，旅行时间在冬季增加，此时较大比例的水流经含水层较温暖的下部，而在夏季减少，此时含水层上部较温暖。
