Lecture-9-Modelling of Lake-Aquifer Interactions.

Abstract

Water bodies are the common features on the land surface and are important in respect of various water uses. Keeping in view their importance in many hydrologic and economic fields, their hydrologic studies are of much use. Field and theoretical studies on the interaction of large water bodies with aquifer are needed based on the variability of flow pattern near the boundaries of the water body. Meyboom (1966) and Freeze and Witherspoon (1967) are amongst the early investigators who stressed upon the groundwater flow pattern around a lake. Winter (1981) has discussed the uncertainties in the water balance of a lake. Some insight into the groundwater regime and discharge estimates from lakes were provided by Winter (1978), who used two- and three- dimensional steady state models for hypothetical groundwater-lake systems. McBride and Pfannkuch (1975) used a numerical model to evaluate the vertical component of groundwater flow of a lake for a number of hypothetical settings. In spite of the early recognition of the lake-water management studies, few attempts (Munter and Anderson, 1981; Winter, 1986; Cheng and Anderson, 1993, 1994) have been made towards the understanding of the interaction of water bodies with aquifer. Munter and Anderson (1981) showed that two- and three-dimensional groundwater flow models provide flexible and effective means of calculating flow rates around lakes. They observed that the anisotropy ratio of aquifer hydraulic conductivity has a significant effect on the simulated head distribution around the lake and magnitude and distribution of seepage from the lake. It is observed that no guidelines or method is available for estimating the recharge from water bodies. In this paper, a diagnostic curve is developed for estimating the recharge from a water body, from the groundwater heads near the water body. The diagnostic curve is developed using the results of MODFLOW application. Additionally, the proposed diagnostic curve can also be used to estimate the aquifer parameters from measured values of the groundwater head and recharge.