PNNL

Abstract

Seepage chambers have been used to characterize the flux of water across the water-sediment interface in a variety of settings. In this work, an electronic seepage chamber was developed specifically for long-term use is a large river where hydraulic gradient reversals occur frequently with river stage variations. A bi-directional electronic flow meter coupled with a custom built seepage chamber was used to measure temporal changes in the magnitude and direction of water flux across the water-sediment interface. The seepage chamber is capable of measuring average specific discharge as low as 1 x 10-6 cm/s over a 15-minute period. The specific discharge measured from the seepage chamber compared favorably with measurements of vertical hydraulic gradient and vertical hydraulic conductivity measured adjacent to the seepage chamber, demonstrating the effectiveness of the electronic seepage chamber to quantify water flux in two directions over a multi-month period.