| Time: |
June 1, 2010 |
| Lecturer: |
Anna Kuhlmann
Institut für Wasserbau, Universität Stutttgart |
| Venue: |
Pfaffenwaldring 61, Raum U1.003 (MML), Universität Stuttgart
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| Download as iCal: |
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The development of effective irrigation strategies is of great importance for agriculture in arid areas as the scarcity of water during extended dry periods leads to limited water uptake by roots and thus to restricted yield production. To approach this goal and gain a deeper understanding, an analysis of the factors influencing the distribution of the flow properties and the interactions with root uptake by plants is essential.Soil structure is supposed to have a large impact on water flow especially under dry conditions when the variability of soil parameters is increased. To account for the emerging uncertainty about the detailed distribution of soil parameters due to few measurement points on the field scale, stochastic methods in which heterogeneity is described by a random parameter field are used.In this presentation, the interrelation of root uptake and heterogeneity is analyzed using numerical simulations. Random parameter fields with Gaussian and non-Gaussian dependence were used as input for the numerical model. Transpiration is considered in a macroscopic way as a sink term with a prescribed potential extraction rate at each node. With this basic model, water flow in a two dimensional random fields has been investigated under dry conditions. It was observed that dry spots - regions in which roots dry up to the wilting point form when the structure shows isolated high extreme values in the conductivity. This process seems rather unrealistic as sufficient water is available at other locations of the domain. Thus another approach is analyzed in comparison to the basic root model where additionally an optimizing mechanism as preferential uptake in wet parts of the soil is included. With this setup the hydraulic variables are investigated in order to gain insight into the joint effect of the underlying structure and the root uptake strategy.
