TR-10 : Determination of reach transmissivity under various hydrologic boundary conditions

Abstract

Reach transmissivity for a canal or stream is a site specific constant which depends on canal geometry and aquifer boundary. The reach transmissivity, when multiplied with depth to water table position from the water surface in the canal measured at some observation point in the vicinity the canal, gives the seepage rate. In the present report, the reach transmissivity for various sub-soil conditions have been reviewed. Analytical solution for reach transmissivity pertaining to a canal embedded in a porous medium underlain by a highly permeable layer, has been obtained using Zhukayskyis function and conformal mapping. Results have been presented for various position of water table above the highly permeable layer. The active seepage zone is under the canal and the phreatic lines merge with the water table within a distance of thrice the width of water surface from the centre of the canal.