Unsteady Free Surface Ground Water Seepage

Seepage in a two-dimensional unconfined aquifer of rectangular cross-section is analyzed to allow prediction of the fall of the free surface and the rate of outflow into an adjoining water body which fully penetrates the aquifer. Use is made of saturated Darcy flow theory with and without the Dupuit assumptions. It was found that if the length of the aquifer is larger than four times its depth, the Dupuit assumptions can be applied to predict positions of the water table with adequate precision. The present numerical results obtained by the two-dimensional flow model are in agreement with those obtainable experimentally by means of the Hele-Shaw model.