Vulnerabilidade ambiental do projeto piloto de irrigação Manuel Alves – Dianópolis – Tocantins

Abstract

This dissertation seeks to assess the interaction between the different components of the environment and the way this information may be able to support environmental planning and management at an area that will be used for irrigated agriculture. The “Pilot Irrigation Area of the Manuel Alves River” is at the Municipality of Dianópolis, State of Tocantins, and is under the “Water Perennialization Program of the State of Tocantins” (PROPERTINS). The objectives of this program, amongst others, are: the inception of irrigated agriculture, the introduction of irrigating technology and the development of irrigated fruit crops in the region. This study used a methodology based on Landscape Ecodynamics (Tricart, 1977) and image interpretation. According to this concept, landscape is the product of a series of different elements, such as soils, geomorphology, ecology and social economy. Depending on the combination of these elements and their spatial arrangement, different levels of vulnerability are derived. In order to access and integrate all these elements a Geographic Information System was used. This allowed cartographic and attribute data to be stored in the same database so soils, geology, geomorphology and land cover and use maps were produced. Based on a scale proposed by Tricart (1977) for vulnerability, each theme’s class was given a value varying from 1 to 3. Overlaying these maps resulted in the Vulnerability Map for the “Manuel Alves River” Hydro-agricultural Project. The final classification shows that 63% may be classified as moderately vulnerable. The climatic characteristics related to rain concentration, a predominance of incept soils, even under slightly undulated relief, and the present existence of a vegetation cover of low density lead to the identification of natural environmental limitation to the proposed activity. This limitation, expressed in the form of a map, may support the management and planning of sustainable irrigated agriculture, making it possible to take for sure that presently existing irrigated projects in the country shall account for these limitations and incorporate management techniques that consider these natural enforcements, having as final objective their sustainability.