Ground Water Department (AP), Hyderabad, India.
Environ Monit Assess. 2011 Jul;178(1-4):309-19. doi: 10.1007/s10661-010-1691-1. Epub 2010 Sep 9.
Water table fluctuation (δh) can be used to rapidly assess changes in groundwater storage. But δh gives acceptable results only if the point of observation is ideally located in the catchment of interest and gives average δh of the area, a condition which is rarely met. However, if large numbers of observation wells are located within a basin (a catchment) the average δh can be computed and used. But, a better way is to use points obtained by shallowest water level and deepest water levels to construct a wedge of water table fluctuation across the area of interest; the mean height of this wedge can be assumed to be the mean δh in the area. And when there is only one observation well, the fact that water table is a subdued replica of the topography, is made use to construct the wedge of water table fluctuation. The results from some randomly selected observations in typical semi-arid, hard rock environment in Andhra Pradesh show that through this approach mean δh can be effectively used to get change in groundwater storage in area. The mean recharge obtained in this study is in the order of 75 and mean draft is 58 mm/a, while mean recharge and draft obtained by conventional technique are 66 and 54 mm/a, respectively. The most likely specific yield around the middle reaches of a catchment ranges between 0.012 and 0.041 which is within the range given by Groundwater Estimation Committee of India for hard rocks.
水位波动（δh）可用于快速评估地下水储量的变化。但是，只有在观测点理想地位于感兴趣的流域内并且给出该区域的平均δh时，δh 才会给出可接受的结果，这种情况很少见。然而，如果在一个盆地（流域）内有大量观测井，则可以计算并使用平均δh。但是，更好的方法是使用最浅水位和最深水位获得的点来构造穿过感兴趣区域的水位波动楔形；可以假设这个楔形的平均高度是该区域的平均δh。当只有一个观测井时，可以利用水位是地形的柔和复制品这一事实来构造水位波动楔形。在安得拉邦典型的半干旱、硬岩环境中随机选择的一些观测结果表明，通过这种方法可以有效地利用平均δh 来获取该区域地下水储量的变化。本研究中获得的平均补给量约为 75mm/a，平均开采量为 58mm/a，而传统技术获得的平均补给量和开采量分别为 66mm/a 和 54mm/a。在流域中游地区，最有可能的特定产水量在 0.012 到 0.041 之间，这在印度地下水估算委员会给出的硬岩范围内。
