TR-75 : Study of spring and hydrologic modelling of spring flow

Abstract

Springs are outlet through which the groundwater emerges at the ground surface as concentrated discharge from an aquifer. Springs are part of the groundwater system can be taken as a flowing well with constant head. They could occur in various sizes from small trickle to large streams. Conditions required for having a spring are manifold and these are various combinations of geologic, hydrologic, hydraulic, pedologic, climatic and biologic controls. A few spring may indicate the existence of thick transmissive aquifers whereas frequent small springs tend to indicate thin aquifers of low transmissivity. Springs not only aid in the evaluation of groundwater potential of the area, it can be used to meet and supplement the different requirements for water of the area. There are various types of spring flow domain depending on aquifer geometry and other physical factors. Discharge rate from a spring depends on the size of the recharge area above it, the rate of precipitation in the area, aquifer geometry, geology and geomorphology of the area, storage coefficient and transmissivity of the aquifer.

There are many springs in the Himalayas, Western Ghats and other places in the country. But, yet there is no systematic study of the spring flow for harnessing them as a dependable source of water. There is enough scope of research in this regard particularly in respect of the mathematical modelling of spring flow.

Jacob Bear (1979) suggested a simple mathematical model to analyze the unsteady flow of a spring with steady state recharge. In the present study, the model suggested by Bear has been improved upon to account for time variant recharges that contribute the spring flow with the help of discrete kernel approach. Variations of spring flow discharge with time in response to variable recharge input for different aquifer parameters have been presented. Another model of spring flow visualising the flow domain as pipe flow as encountered in fractured rocks has been developed.