TR(BR)-121 : Assessment of recharge from partially penetrating in fluent stream

Abstract

The exchange of flow between a stream and an aquifer can be estimated solving the differential equation governing the flow using either an analytical or a numerical method. Solution of Laplace equation, which satisfies the boundary conditions prevailing at the flow domain boundaries, enables quantification of steady state seepage from the stream. For unsteady state condition Boussinesq's equation is solved satisfying the initial and the boundary condition. Using analytical methods the exchange of flow is obtained as a non dimensional term. To obtain the numerical value, the different terms such as hydraulic conductivity, storativity, and potential difference and stream geometry factor which appear in the dimensionless term are required to be quantified.

Using conformal mapping technique an expression of steady state seepage from a partially penetrating stream has been derived in this study. The expression relates the seepage to the potential difference at an observation well and the geometry of the flow domain. The conductivity can be estimated from dilution technique if the gradient of the flow line at the observation well is monitored.