Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based water flux calculation
Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based water flux calculation
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DOI：
10.5194/hess-15-3495-2011
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发表时间：
2011-11
影响因子：
6.3
通讯作者：
M. Munz;S. Oswald;C. Schmidt
中科院分区：
文献类型：
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作者：
M. Munz;S. Oswald;C. Schmidt
抽象的。基于热传输方程一维解的地下水通量的量化取决于测量的地下温度的准确性。在本实验研究中，系统地评估了温度探头设置对垂直水通量计算精度的影响。在沙箱实验中安装了4个温度探头装置，在控制水通量为±1.3m d−1的范围内测量了时间高分辨率垂直温度廓线。带通滤波提供了随水通量变化的昼夜温度信号的幅度差和相移。直接安装在饱和泥沙中的设置的幅值比随砂箱水力坡度的变化而显著变化。振幅比为水流速度的分析计算提供了准确的基础，与测量的流速相匹配。计算的流速对饱和沉积物的热物性和温度传感器间距很敏感，但对等于溶质分散度的热分散度不敏感。间接安装在测压管内的温度探头的幅值比受管内热交换过程的影响，且仅随水流量方向变化显著。所有设置的小传感器距离的温度时滞被发现对垂直水通量不敏感。
Abstract. Quantification of subsurface water fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical water flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled water fluxes in the range of ±1.3 m d−1. Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on water flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with water flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical water flux.