[1] The work presented here describes a new modeling infrastructure of irrigation which is integrated in a land surface model and which will make this model a suitable tool for studies of interactions between irrigation water use and climate change. The model is presented and validated off-line over the Indian Peninsula. Numerical experiments are conducted with a 1 degree spatial resolution land surface model. Two 2-year simulations, forced by the ISLSCP (1987 -88) data sets, are conducted with and without irrigation. The analysis focuses on irrigation modeling validation and briefly presents first results on irrigation's impact on the surface fluxes.

From 1996 to 1999, an European project called WELSONS was led to better understand the impacts of changes in climate and land-use on soil degradation by wind erosion for agricultural soils in a semiarid region of north-east Spain (Central Aragon). This paper presents the main results obtained from the measurement activities of the WELSONS project aimed to generate an original data base to study wind erosion processes. The first objective was to evaluate the effects of climate and anthropogenic processes on surface characteristics of agricultural soils. During the whole WELSONS experiment, a physical dynamics characterization of the soil surface and of the atmosphere near the ground were determined for each field plot studied. Results from the characterisation of soil surface shows that reduced tillage (RT) lower soil erodibility by wind compared to conventional tillage (CT).Soil crusting, which is a common feature of soils in the area, can also be considered as a protecting element against wind erosion. The second objective was to study the mobilisation processes of soil-particles into the saltation layer. Strong and erosive Cierzo winds occurred frequently in the area of the experimental field, but because a soil surface crust was present, only a limited supply of material was available for wind erosion. However, a measured saltation transport flux could be obtained for each sampled period from the measurement of the mass of saltating particles transported during each erosion event. The third objective was to assess the atmospheric emission of fine dust into the suspension layer. Significant vertical dust flux of PM20 was observed only in the CT plot because, as the erosion events are supply-limited, a lower amount of material lying on the crust was transported by the wind and sandblasted to provide suspended dust. Finally, the sandblasting efficiency calculated in the present experiment could be interpreted as the result of a higher binding energy for silt loam soil particles compared to sandy loam, loamy sand and sandy textured soils.