Impact of groundwater regimes on water balance components of a site with a shallow water table

Abstract

The management of shallow water table sites is often the subject of discussion between different interest groups, the most controversial topic being the different target groundwater levels. A good level of knowledge about the effects of the different water levels on the water budget components is a precondition for the development of compromises in well‐balanced water resource management. We used groundwater lysimeters to investigate the impact of different water level regimes on the water balance. The lysimeters were installed directly within a typical shallow water table site and had a specially designed system to control the lower boundary condition. This enabled us to simulate different management options in a realistic way. Our results show increasing evapotranspiration with higher water levels but only if the vegetation is adapted to these conditions. Adaptation may take place within a few years of higher water levels. High water levels in spring are linked to increased water storage. This can help to compensate for the higher evapotranspiration for some weeks but not for the entire season. The meteorological conditions have a large short‐term impact on the water budget, which is difficult to compensate for using long‐term water management strategies or slow‐responding vegetation development. Our results underline the complex ecohydrological dependencies in such site conditions and could be an important basis for the development or improvement of ecohydrological models.

The Role of the Unsaturated Zone for Rainwater Retention and Runoff at a Drained Wetland Site

“…This makes the ETa more important during dry conditions due to the longer duration of the runoff process and, to a certain extent, the higher evaporative demand in such periods. Yet the latter also depends in a complex manner on the vegetation, its growth and adaptation to the current water tables as shown by Dietrich and Kaiser [53]. Our results underline the conclusions by Bacon, et al [5] regarding the common perception that peatlands act like as sponges.…”

The influence of increasing mineral fertilizer application on nitrogen leaching of arable land and grassland—results of a long-term lysimeter study

“…A combined multifactorial lysimeter experiment with the experimental components mineral fertilization, land use, and soil type was set up to clarify the relationships between the level of mineral N fertilization and the leachate-bound nutrient discharge (62). Lysimeter experiments are especially suited to investigate water and solute fluxes in soils (63)(64)(65)(66)(67)(68). Therefore, a long-term lysimeter experiment was created at the Lysimeter facility of the UFZ in Falkenberg (coordinates 52.859780 N, 11.812595 E) in 1985.…”

Measuring changes in forest floor evaporation after prescribed burning in Southern Italy pine plantations

“…Hence, canopy and forest floor interception and the successive evaporation flux are important parts of the total water balance (Herbst et al, 2008;Murray, 2014) and, for this reason, especially forest floor interception has to be considered if one wants to know the effect of prescribed burning on soil water balance. To measure evaporation from the topsoil often lysimeter-like set-ups are used (Dietrich and Kaiser, 2017;Gerrits et al, 2007;Li et al, 2000;Magliano et al, 2017;Schaap and Bouten 1997;Stumpp et al, 2007) or field samples are weighted in wet and dry conditions (Helvey, 1967;Pathak et al, 1985;Putuhena and Cordery, 1996). The disadvantages of these methods are that the litter and fermentation layers are disturbed and/or that the "measuring device" is disturbing the measurement (e.g., edge effects for wind, drainage problems) (Gerrits and Savenije, 2011;Pruitt and Angus, 1960).…”