The potential of karst aquifers as a drinking water resource is substantial because of their large storage capacity gained in the course of carbonate dissolution. Carbonate dissolution and consequent development of preferential paths are also the reasons for the complex behavior of these aquifers as regards surface and underground flow. Hydrological modeling is therefore of paramount importance for an adequate assessment of flow components in catchments shaped on karsts. The cross tabulation of such components with geology, soils, and land use data in Geographic Information Systems helps decision makers to set up sustainable groundwater abstractions and allocate areas for storage of quality surface water, in the context of conjunctive water resources management. In the present study, a hydrologic modeling using the JAMS J2000 software was conducted in a karst area of Jequitiba River basin located near the Sete Lagoas town in the state of Minas Gerais, Brazil. The results revealed a very high surface water component explained by urbanization of Sete Lagoas, which hampers the recharge of 7.9 hm3 yr−1 of storm water. They also exposed a very large negative difference (−8.3 hm3 yr−1) between groundwater availability (6.3 hm3 yr−1) and current groundwater abstraction from the karst aquifer (14.6 hm3 yr−1), which is in keeping with previously reported water table declines around drilled wells that can reach 48 m in old wells used for public water supply. Artificial recharge of excess surface flow is not recommended within the urban areas, given the high risk of groundwater contamination with metals and hydrocarbons potentially transported in storm water, as well as development of suffosional sinkholes as a consequence of concentrated storm flow. The surface component could however be stored in small dams in forested areas from the catchment headwaters and diverted to the urban area to complement the drinking water supply. The percolation in soil was estimated to be high in areas used for agriculture and pastures. The implementation of correct fertilizing, management, and irrigation practices are considered crucial to attenuate potential contamination of groundwater and suffosional sinkhole development in these areas.

Este trabalho tem como objetivo realizar a caracterização morfométrica da bacia hidrográfica do Córrego do Marinheiro, Sete Lagoas - MG, utilizando-se ferramentas de geoprocessamento, como subsídio à sua análise hidroambiental. O método foi desenvolvido em três etapas principais, quais sejam: i) Pré-processamento do MDE; ii) Delineamento hidrológico; e iii) Cálculo de parâmetros morfométricos da bacia do Córrego do Marinheiro. Foi possível verificar que a Densidade hidrográfica (Dh) calculada para a Bacia do Córrego do Marinheiro foi de 2,7 un.km-2, ou seja, a cada quilômetro quadrado existem 2,7 canais. A declividade média encontrada na bacia do Córrego do Marinheiro foi de 13%, valor condizente com o relevo do tipo ondulado. A bacia pode ser classificada como de 3ª ordem, além de apresentar sistema de drenagem do tipo dendrítica. O Índice de sinuosidade (IS) calculado foi de 20,6%, valor que classifica o Córrego Marinheiro como reto. Os valores de declividade do álveo encontrados foram de S1 igual a 0,03 m.m-1; S2 igual a 0,008 e S3 igual a 0,011. Concluiu-se que, de acordo com os parâmetros de geometria da bacia Kc (coeficiente de compacidade), Kf (fator de forma), Re (razão de elongação) e IC (índice de circularidade), na bacia há pouca tendência à ocorrência de inundações, em condições normais de precipitação, devido à sua forma alongada. Para aprimorar a caracterização das linhas de drenagem indicadas no MDE, são recomendados estudos mais detalhados, com medidas em campo e monitoramento dos canais, que permitam a diferenciação entre os cursos d’água perenes, intermitentes e efêmeros e as ravinas secas.

A correct and accurate cartographic representation of the relief of watersheds is increasingly required due to the increased human actions on water resources. The objective of this work was to propose a conversion of the digital surface model (DSM) to the hydrologically conditioned digital elevation model (HCDEM) for the Marinheiro Stream Watershed in Sete Lagoas MG, Brazil, as a subsidy for hydrological and environmental analyses in this region. The methodology was developed in seven stages: a) Automatic classification of the Geoeye image; b) Ordinary kriging of the DSM points for areas without arboreous vegetation; c) Obtaining of the contour lines; d) Obtaining of points of exposed soil areas of the DSM and obtaining of the drainage network; e) Obtaining of the hydrologically conditioned digital elevation model (HCDEM); f) Correcting of the topographic profile of the drainage network region; and g) Analysis of the results. According to the results, the conversion of the model minimized the canopy effects and increased the coherence of the representativeness of the relief surface. The standard deviation found was 3.9 m, confirming the better performance of the HCDEM over the DSM, which presented a value of 4.95 m. Therefore, according to the validation points obtained in the field, the product of this study has a consistent basis for accurate and reliable hydrological, geomorphological, and geo-ecological analyses in the evaluated watershed.

A correct and accurate cartographic representation of the relief of watersheds is increasingly required due to the increased human actions on water resources. The objective of this work was to propose a conversion of the digital surface model (DSM) to the hydrologically conditioned digital elevation model (HCDEM) for the Marinheiro Stream Watershed in Sete Lagoas MG, Brazil, as a subsidy for hydrological and environmental analyses in this region. The methodology was developed in seven stages: a) Automatic classification of the Geoeye image; b) Ordinary kriging of the DSM points for areas without arboreous vegetation; c) Obtaining of the contour lines; d) Obtaining of points of exposed soil areas of the DSM and obtaining of the drainage network; e) Obtaining of the hydrologically conditioned digital elevation model (HCDEM); f) Correcting of the topographic profile of the drainage network region; and g) Analysis of the results. According to the results, the conversion of the model minimized the canopy effects and increased the coherence of the representativeness of the relief surface. The standard deviation found was 3.9 m, confirming the better performance of the HCDEM over the DSM, which presented a value of 4.95 m. Therefore, according to the validation points obtained in the field, the product of this study has a consistent basis for accurate and reliable hydrological, geomorphological, and geo-ecological analyses in the evaluated watershed.