Reducing the impact of wave attack: dunes as natural buffers

Coastal dune systems, with their self-regenerating capacity after storm erosion, represent natural defense zones against flooding of the hinterland. Condition: the total dune volume exceeds a certain minimum value related to the safety standard. As such, coastal dune systems represent natural buffers to climate change. To maintain the functions of the dune system at a certain level under conditions of sea level rise, the dunes require an input of sand proportional to the rate of sea level rise. Focus of the research is on the problem of how sediment supply and dune management may be optimized under conditions of climate change in order to sustainably preserve the safety function of the dunes in harmony with other functions of the system. The aim of this project is to derive a model of dune development and apply it together with other models and expert judgment, to develop and evaluate a set of potential dune management strategies, aimed at improvement of the climate buffer function of dunes. This text is an extract of the full project proposal

The concept of matric flux potential applied to simulation of evaporation from soil.

Two simulation models of evaporation were based respectively on (a) soil matric flux potential and (b) soil hydraulic conductivity and water potential. Mathematical analysis showed that the former method gave a lower and more accurate estimate of soil water movement in unsaturated soil, and therefore of evaporation from the soil. The difference between the accuracy of the two methods tended to be greatest in soils of coarse texture. The matric flux potential method required less computer time than the other method did. (Abstract retrieved from CAB Abstracts by CABI’s permission

Environnement humain de l'érosion

Dans le cadre des évaluations économiques des mesures de conservation des eaux et du sol, on propose d'utiliser des méthodes et modèles existants pour déterminer les effets de ces mesures sur l'érosion et sur les bilans d'eau et d'éléments nutritifs et ensuite les effets des changements sur les rendements. Dans ce texte on présente des "feuilles de calcul", y incluant ces bilans et effets, afin de calculer les bénéfices des mesures de CES. Un exemple concerne l'évaluation économique des cordons pierreux au Burkina Faso. (Résumé d'auteur

Water movement in layered soils. 2. Experimental confirmation of a simulation model.

For predicting the rain infiltration front in a layered soil the simulation model written in CSMP (Continuous System Modelling Program) described by van Keulen and van Beek (1971) gave results that were in good agreement with the predicted infiltration behaviour. [132.3: 968.114. (Abstract retrieved from CAB Abstracts by CABI’s permission

Infiltratie en herverdeling van water in grond

The flow of the liquid phase trough a soil can be predicted from pressure gradients. Different ways of predicting infiltration for irrigation of a basin were compared: numerical approximation; semianalytical; and analytical. A partly emperical equation was developed for description of rate of infiltration, after examination of existing equations. Under certain condions, infiltration was influenced by under or over pressure of the trapped gas phase and by swelling of clays. Complex models for redistribution were of little value in practice, since they could not be generalized and required too much physical data about the soil. A scheme was developed that grouped techniques for estimating physical properties of soil, according to cost and expertise required.</p