See more from this Session: Symposium--Advances In Soil and Vadose Zone Hydrology: The Contributions of Glendon Gee: I
A field-scale test section consisting of compacted clay cover was built and instrumented to investigate the adequacy of the lysimeter to measure percolation. Lysimeter pan was installed within the middle of the test section and the instrumented area of the test section was expanded upslope and downslope of the lysimeter to monitor the soil water storages within and beyond the lysimeter footprint where the clay cover was hydraulically connected to the underlying landfilled waste. The numerical model UNSAT-H was used to simulate the water balance of the lysimeter. The lysimeter-validated model was then used to simulate the water balance of the actual cap. Both field data and numerical simulations indicated slightly higher soil water storage for the actual cap than the corresponding lysimeter. A series of numerical analyses showed that when a lysimeter underestimates the soil water storage of an actual earthen cap, it corresponds to greater actual percolation across the interface between the soil cover and the underlying waste. A lysimeter overestimates percolation because the infiltrated water drained into the lysimeter is immediately removed and is therefore not available for removal by evapotranspiration.