Análise da vulnerabilidade e risco à escassez hídrica no semiárido - caso de estudo Ibaretama/Ce

Abstract

Drought is a natural phenomenon, caused by an extreme climate caused by the deficit of precipitation, which results in the loss of the water storage capacity of the dams, being the rural areas of the semiarid the most vulnerable and affected, generating social and economic damages. Among the mitigating measures related to droughts in the semi-arid region, the use of groundwater stands out, the mapping of areas at risk of water insecurity is an important instrument for public managers in decision making. In this context, the objective of this thesis was to propose and apply a new methodology for Mapping Areas of Risk to Water Insecurity (MARIH). The pilot area covers the municipality of Ibaretama / CE, due to its extensive history of drought events. The measurement of risk, in general, comprises the analysis of vulnerability (lack of access to water - tubular wells) and danger (occurrence of drought). Thus, having the Territorial Analysis Unit (UTAs) that consists of cells of 1 x 1 km, the set of variables was analyzed, built from socioeconomic indicators (inhabitants, agricultural establishments and access to water) and geoenvironmental indicators (rainfall, topography, soil infiltration capacity and aquifer lithology), the UTAs being classified according to their water risk in: low (R1), moderate (R2), high (R3) and very high (R4). As a result, we have that the municipality of Ibaretama, was divided into a total of 985 UTAs, with 342 UTAs with water risk identified, of these 32 were classified as high risk and 22 of very high risk. The Fractured Aquifer, the main underground source in extension and number of existing wells, with an average specific flow of 0.22 m3 / h / m. Of the 105 registered tubular wells, 5 (4.00%) are abandoned; 20 wells (16.00%) are deactivated and the 100 (80.00%) wells are in operation. The public authorities own the majority of these wells, 92 (73.60%), the private sector 32 (25.60%). The application of the MARIH tool proved to be applicable to map the vulnerability to water insecurity, with the application of the method being ensured in other municipalities. Its execution is characterized by: i) simplicity, which provides the large-scale automation process; ii) flexibility, it can be used in rural areas, from various types of cutouts, in this case the municipal one was used and iii) low execution cost, as publicly available data, provided by SIAGAS / CPRM and IBGE, is used. Through this methodology, it was determined which UTAs are at greatest risk, which should be the target of public policies and mitigation measures, determining the priority areas for public investments.