Lysimeters at the Hanford Site: present use and future needs

Lysimeters have been built and used at the Hanford Site for a variety of reasons, including the assessment of recharge (drainage) rates, biointrusion studies, the development of shallow-land burial monitoring and measurement methods, radionuclide transport studies, evapotranspiration studies, and field-scale waste-form leaching tests. A common feature of lysimeters is that they provide a way either to directly measure or to estimate water balance parameters such as soil-water storage changes, evapotranspiration, and drainage for a given site. The number of water balance parameters and the precision with which they can be measured vary depending on the design features of the lysimeter. In this report we describe key design features of the six major lysimeters facilities at Hanford and the types of data available from them. We also address the deficiencies of the present facilities for adequately determining recharge rates and propose additional facilities to evaluate protective barrier systems and arid-land water dynamics. 44 refs., 9 figs., 4 tabs.