Abstract : This thesis aims to develop a land use module for the applied economic model NEMESIS which is a detailed model for European Union. This dissertation also proposes the use of the land use module with the NEMESIS model in order to analyse the effects of European policies especially their economic and land use impact. The first chapter describes, on one hand, the construction of a database on land use and, on another hand, explain the development of a land use module for the EU countries by using agricultural land supply and demand but also an modelling of urban land use. The second chapter regards, using two applications, the problem of scenario construction in applied modelling. A first scenario, constructed with an extrapolating approach, is presented and analysed. This scenario is also used as reference scenario for the assessment of European policies. A second application shows four scenario developed using an imaginative approach i.e. assuming different possibilities for the future change in main drivers. The third chapter presents and describes the functioning of four linked models which is used for the economic and environmental assessment of a European agriculture liberalisation with re-allocation of released funds either by consumer tax rebate or a subsidy to R&D investments. The linked models included (i) the NEMESIS model, (ii) the CAPRI model a detailed agricultural model, (iii) the EFISCEN model, a forest resource management model and(iv) the Dyna-CLUE model, a detailed model for land use allocation. Finally, the last chapter presents, after the construction of indicators about nutrient use in agriculture, the economic assessment of two European policies: firstly, a biodiversity conservation policy in forest area or in agricultural land and secondly a biofuel development policy at European level.