Advanced technologies in lysimetry

Abstract

The ability to quantify soil water flow is a prerequisite for the accurate prediction of solute transfer within the unsaturated zone. Monitoring these fluxes is a challenge because the results are required for answering not only scientific but also practical questions regarding the protection of groundwater, the sustainable management of agricultural, forestry, mining or set aside industrial areas, the reduction of leachate loss from landfills, and for explaining the fate of environmentally harmful substances. Both direct and indirect methods exist for estimating water flux rates; these have been applied with varying success. In Europe, the use of direct lysimetry methods for measuring water and solute fluxes in soils has increased significantly in recent years. Although this technique generates reliable drainage data, it involves relatively high investment and maintenance costs. New lysimeter techniques have been developed to tackle this problem. It is now possible to collect large monolithic soil columns and to measure the soil water balance of these monoliths (surface area 0.03-2 m2 and depth to 3 m) with a high degree of precision (±20 g). Furthermore, progress in lysimetry enables us to ascertain experimentally the mass input of dew and to calculate actual evapotranspiration, precipitation and seepage rates. Weighable groundwater lysimeters have been developed in addition to gravitation lysimeters. Different lysimeter types and their usage will be presented and explained using practical examples.