Theme 2-4-A two dimensional groundwater flow model for spring

Abstract

The Bear’s springflow model and the model with long transmission zone, assume the flow to be one-dimensional. However, in reality, the flow pertaining to a spring is three-dimensional. Using the Dupuit-Forchheimer assumptions, some three-dimensional flow process could be dealt as two-dimensional. A springflow domain can be visualized to have a recharge area, which may not be well defined, and a discharge area acts as the spring. Hantush (1967, vide Bouwer, 1978) has given solution for the rise of piezometric surface due to uniform recharge at a constant rate from a rectangular basin. The shape of the recharge area for a spring can be considered as rectangular. Similarly, a rectangular shape can be assumed for the spring’s opening. Using the Hantush’s basic solution for the rise of piezometric surface due to recharge from a rectangular area, a two-dimensional springflow model has been developed in this paper. The method of image is applied to convert the finite flow domain into an infinite one.

In this model, the spring aquifer system is an open system. Therefore, all the discharge does not appear as a springflow. The variation of logarithm of a springflow with during recession does not follow a straight line. Only towards a later part of the recession the variation is approximately linear. Using the random jump technique and the springflow model for an open flow domain, recharge area, spring opening, distance of the spring from the recharge area, transmissivity and storativity of the transmission zone and the recharge have been estimated from observed springflow data from the Kirkgoz spring in Turkey. Since the domain is an open one, the recharge computed by the model, which is based on Hantush’s solution, is found higher than those computed using the model for a closed system.