This title appears in the Scientific Report :
2014
Numerical study on the potential impact of different bottom boundary conditions on the water balance of lysimeters
Numerical study on the potential impact of different bottom boundary conditions on the water balance of lysimeters
The SOILCan lysimeter network is a large scale climate feedback experiment and is embedded in the four longterm observatories of TERENO (TERestrial ENvironmental Observatories). The focus of the SOILCan-project isto observe the impact of climate change on water and matter budgets in different grass-...
Saved in:
Personal Name(s): | Groh, Jannis (Corresponding Author) |
---|---|
Vanderborght, Jan / Pütz, Thomas / Vereecken, Harry | |
Contributing Institute: |
Agrosphäre; IBG-3 |
Published in: | 2014 |
Imprint: |
2014
|
Conference: | General Assembly 2014 - European Geosciences Union, Vienna (Austria), 2014-04-27 - 2014-05-02 |
Document Type: |
Poster |
Research Program: |
Terrestrial Systems: From Observation to Prediction Modelling and Monitoring Terrestrial Systems: Methods and Technologies |
Publikationsportal JuSER |
The SOILCan lysimeter network is a large scale climate feedback experiment and is embedded in the four longterm observatories of TERENO (TERestrial ENvironmental Observatories). The focus of the SOILCan-project isto observe the impact of climate change on water and matter budgets in different grass- and arable-land lysimeters.The monitoring infrastructure was established across a rainfall and temperature transect along which lysimeterswere transported from wetter to drier conditions.The lysimeters in SOILCan have a controlled bottom boundary condition using a rack of suction candles thatenables upward and downward flow of water. This pressure head at the bottom is controlled by measured soilwater potentials in undisturbed soil in the close vicinity of the bottom of the lysimeter. For transported lysimetersthis controlling approach no longer works as the surrounding soil profile and both its upper climatic boundaryconditions and lower boundary conditions related to its hydrogeological setting differ from the place where thelysimeter was taken from. In order to evaluate these artefacts and to derive a suited approach to control the lowerboundary of transported lysimeters, water balance simulations were run. We analyzed three different approachesto impose bottom boundary conditions for transported lysimeters. A ‘zeroth-order’ approach is to define thebottom boundary at the bottom of the lysimeter and use the pressure heads measured at the location from whichthe soil lysimeter was taken. However, this approach is prone to artefacts since these bottom boundary conditionsare determined by the climate at the site where the lysimeter was taken from. A ‘first-order’ approach is to definea bottom boundary condition at a certain hydrogeological boundary that can be defined deeper in the soil profilesuch as a seepage face or a groundwater table. However, for shallow groundwater tables, this approach may alsolead to artefacts since the depth of the groundwater table may change with changing climate. In a ‘second-order’approach, the effect of changing climate conditions on these bottom boundaries is evaluated. Therefore, otherhydrogeological properties that determine lateral groundwater flow such as the depth of an impermeably layerand the distance between surface water structures that drain groundwater have to be considered in the approachas well. We will present a comparison of these approaches using water balance results derived by numericalsimulation with the software HYDRUS 1-D. |