A spatial model for analysing impact of land use catchment policies in water resources : a case study in South of Brazil

Although several models exist, the availability of information to run such models is usually very limited and few of those available are easy to use, can operate over a variety of conditions, and integrate the wide range of information that planners and managers need. In this context, the development of a regional modelling framework for assessment the impact of management activities on catchments is extremely challenging because of the expansive and heterogeneous land areas on which the activities occurs. The models must represent the resource diversity and the continuum of production practices that may be employed under alternative resource settings. In addition to a strong physical component, modelling framework must also include a component which simulates the decision making of water users procedures. This paper presents a spatial model that is capable of estimating the effects of scenarios on water resources. Several authors have noted the critical need for knowledge about why landscape changes occur and how environmental factors interact. Rivers and streams, for example, frequently are used as jurisdicional boundaries, bisecting catchments. Consequently, the units for which land management and planning are undertaken frequently little attention is given to the water resources and environmental system inside then and their connections and/or to their links to economic and social processes. In the light of the new Water Resources Policy in Brazil (since 1997), this paper attempts to make greater and more consistent use of economic instruments to water allocation as a complement or a substitute to other policy instruments such as regulations, taking into account physical-socio-economic conditions. With the use of this framework it is expected improvement in the allocation of water resources and efficient use of natural and environmental resources by means of economic instruments so as to better reflect the physicalsocial-economic costs of the use of these resources. To do that a better modelling and forecasting