ID Artigo: 933
Titulo: How useful are geosciences in making water and other geo-resources available in the semiarid regions?
Resumo: The study of any semiarid region from the geoscientific point of view should: a) be made having in mind the well-being of the respective human communities, their sustainable economic development and the preservation and improvement of the environmental/ecological conditions; b) apply concepts, methods and technologies favouring the rational use of the existing geological resources (georesources) and the exploitation (prospecting) and exploration of new occurrences of such resources; c) take into consideration the past occurrences of natural disasters and the probability of future occurrences. “Georesources†should not be confused with “mineral resources: it is an ampler, more comprehensive concept where water, soil, landscape and mineral resources are included. Water In the semiarid regions water is the most precious resource. Surface and underground water are exploited in various types of reservoirs such as: underground dams of temporary streams and rivers, aquifers (that is, underground water and its host rocks), surface dams of streams and rivers, cisterns and shallow trenches. Hydrogeology is the discipline that deals with water, where it is found, how it moves around and how it interacts with rock and soil. Geotechnical engineer has to do with the construction of the reservoirs. Hydrogeochemistry and Biogeochemistry deal with water types and quality for its various uses. Geophysics is fundamental in understanding the ways water occurs at depth. General geology (mostly mapping) and Pedology (Soil science) must precede all the other studies. Soil Soils derive from rocks. Soil science and Geology are mutually related. Agrogeology is important in agriculture and forestry. It is through soil that surface water percolates, becoming underground water and the upper levels of underground water are in general found in soil. So Soil science and Hydrogeology are also mutually related. Soil is a sampling medium (as well as stream sediments, like sands and clays) frequently used in Mineral prospecting using geochemical methods − namely when the prospector is looking for deposits of metals − as well as in environmental Pollution studies, when the geoscientist has to look at the rock-soil-water-plant system in an integrated way. Mineral resources Mineral resources are traditionally classified in material resources (metals and industrial rocks and minerals) and energy resources (fossil fuels, radioactive fuels and geothermal resources). Geosciences have a vast panoply of concepts, methods and techniques related to their prospecting − among others, Geology, Geochemistry, Geophysics, Remote sensing (using imagery from satellites and airplanes) − and to their exploitation (Mining engineering, Geological engineering, Petroleum engineering, etc.). Relationships of these disciplines with Biology and Statistics are becoming deeper and deeper. If mineral resources are usually thought as occurring on land, it is well known that they also occur on the ocean floor, not only oil, but also other resources, and so the marine zones close to semiarid coastal areas should not be put aside as zones of no interest before studying them. Two main questions related to these resources have become more and more acute in the last decades: the question of the exhaustion of mineral deposits and the question of the environmental effects of their exploration, namely pollution and climatic change. Geosciences may and must participate in the discussion of such questions. Landscape Any landscape has a geological component normally dealt with under the heading Geomorphology/Physical geography. Books, brochures, maps, leaflets, etc. relative to natural parks have been calling more and more the attention of the visitors to that component.In recent years thematic parks have incorporated geoparks and geosites, where geomonuments are found deserving to be admired for geological, geomorphologic, paleontological and biodiversity reasons. Environmental studies Geosciences play an important role in risk assessment and risk management as far as pollution (pollution of soils, waters, air) and natural disasters (earthquakes, tsunami, volcanic eruptions, landslides, floods …) are concerned. If pollution is mostly related to anthropogenic activities and natural disasters are mostly related to natural processes, the former may have natural causes and the latter may be induced by Man. In conclusion: Geosciences have an important word to say when today and tomorrow social, economic and environmental conditions of any semiarid region are considered, and policy-makers and decision-makers should take into account the geoscientist’s views when discussing the present and the future issues of interest for such areas.
Palavras Chave: semiarid