Water table effects on measured and simulated fluxes in weighing lysimeters for differently-textured soils

Abstract

Weighing lysimeters can be used for studying the soil water balance and to analyse evapotranspiration (ET). However, not clear was the impact of the bottom boundary condition on lysimeter results and soil water movement. The objective was to analyse bottom boundary effects on the soil water balance. This analysis was carried out for lysimeters filled with fine-and coarse-textured soil monoliths by comparing simulated and measured data for lysimeters with a higher and a lower water table. The eight weighable lysimeters had a 1 m 2 grass-covered surface and a depth of 1.5 m. The lysimeters contained four intact monoliths extracted from a sandy soil and four from a soil with a silty-clay texture. For two lysimeters of each soil, constant water tables were imposed at 135 cm and 210 cm depths. Evapotranspiration, change in soil water storage, and groundwater recharge were simulated for a 3-year period (1996 to 1998) using the Hydrus-1D software. Input data consisted of measured weather data and crop model-based simulated evaporation and transpiration. Snow cover and heat transport were simulated based on measured soil temperatures. Soil hydraulic parameter sets were estimated (i) from soil core data and (ii) based on texture data using ROSETTA pedotransfer approach. Simulated and measured outflow rates from the sandy soil matched for both parameter sets. For the sand lysimeters with the higher water table, only fast peak flow events observed on May 4, 1996 were not simulated adequately mainly because of differences between simulated and measured soil water storage caused by ET-induced soil water storage depletion. For the silty-clay soil, the simulations using the soil hydraulic parameters from retention data (i) were matching the lysimeter data except for the observed peak flows on May, 4, 1996, which here probably resulted from preferential flow. The higher water table at the lysimeter bottom resulted in higher drainage in comparison with the lysimeters with the lower water table. This increase was smaller for the finer-textured soil as compared to the coarser soil.

Evaluating the transferability of measurements from simple constructed non weighable gravitation lysimeters to predict the water regime on field scale—a case study

“…4a). This could be explained on the one hand by a hindered capillary rise during vegetation period, due to the fact that lysimeters are isolated blocks and on the other hand that a water logged zone has to form at the bottom before water can discharge ( Flury et al, 1999; Shirmohammadi et al, 2005; Gee et al, 2009; Wegehenkel and Gerke , 2015). But correlation analysis between monthly discharge rates of NWGL and field for HY 2013 and 2014 revealed their significant comparability, yielding that these effects were not significant in HY 2013 and 2014 (Fig.…”

The Effects of Soil Drying Out and Rewetting on Nitrogen and Carbon Leaching—Results of a Long-Term Lysimeter Experiment

“…Thus, a nutrient or contaminant front requires about 2 years to flow through the lysimeter soil column with 1 m thickness (at piston flow) under average precipitation conditions. Numerous authors point out the great importance of preferential flow processes for rapid solute transport in soils [71][72][73][74][75][76]. Therefore, a time lag between drought and measurable effects on the substance concentration in the seepage have to be taken into account.…”

Responses of Water Fluxes and Water-Use Efficiency of Maize to Warming Based on Water Transformation Dynamical Processes Experimental Device (WTDPED) Experiment

“…In recent years, some devices with artificial controlled climatic conditions such as the free air carbon dioxide enrichment (FACEs), open-top chamber (OTC) and temperature gradient tunnel (TGT) have been used to study the responses of crop production and soil water dynamics in GSPAC to warming [29][30][31][32][33][34]. Compared to field experiments and modeling practices, the lab/controlled experiments had the advantages of conveniently setting various meteorological conditions and accurately observing the responses of crops and water fluxes to climate change [35].…”

“…using the above lab/controlled devices. Water fluxes such as ET, soil moisture and drainage can be accurately monitored on the basis of water mass balance via field weighing lysimeters [34,36]. However, climatic parameters were seldom controlled in field lysimeters for clarifying the impacts of warming on water balance components and crop growth in GSPAC.…”