The zoning of groundwater recharge potential would be attractive for water managers, but is lacking in many regions around the planet, including in the Jequitiba River basin, Minas Gerais, Brazil. In this study, a physically based spatially distributed method to evaluate groundwater recharge potential at catchment scale was developed and tested in the aforementioned Jequitiba River basin. The data for the test was compiled from institutional sources and implemented in a Geographic Information System. It comprised meteorological, hydrometric, relief, land use, and soil data. The average results resembled the annual recharge calculated by a hydrograph method, which worked as validation method. The spatial variation of recharge highlighted the predominant contribution of flat areas, porous aquifers, and forested regions to groundwater recharge. They also exposed the negative effect of urbanization. In combination, these factors elected the following sectors of the Jequitiba River basin as regions of high recharge potential: the south-southeast part of the headwaters in Prudente de Morais; Sete Lagoas towards the central part of the basin; and the region between Funilândia and Jequitiba, near the Jequitiba river mouth. Some management practices were suggested to improve groundwater recharge. The map of groundwater recharge potential produced in this study is valuable and is therefore proposed as tool for planners in the sustainable use of groundwater and protection of recharge areas.

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.

A erosão do solo tem sido reconhecida há muito tempo como um problema ambiental muito sério, especialmente em regiões onde ocorre interferência antrópica e gestão agrícola sem critérios adequados. Neste trabalho utiliza-se o modelo empírico RUSLE para estimar a perda anual de solos da bacia do córrego Marinheiro, Sete Lagoas – MG. Os resultados mostraram que a perda anual de solos na bacia apresentou valor médio estimado em 7,15 ton. ha-1.ano-1. Além disso, foi possível classificar e caracterizar os resultados obtidos para a área de estudo em seis categorias distintas, quais sejam: 0 a 1 (muito baixa); 1 a 3 (baixa); 3 a 5 (moderada); 5 a 10 (severa); 10 a 20 (alta); e acima de 20 ton. ha-1. ano-1(muito alta). Concluiu-se que, espacialmente, a área apresenta predominância das classes baixa e muito baixa de perda anual de solo (61,7% da bacia). No entanto, 21% da área apresentam riscos ambientais, com tendência do tipo severa a muito alta, devido aos processos erosivos mais intensos. Destaca-se que, segundo o modelo, nas áreas onde houve a implantação de atividades antrópicas, as perdas anuais de solos foram mais acentuadas. Os métodos descritos neste estudo permitiram uma compreensão mais clara da relação entre a erosão e seus principais fatores causais, podendo ser úteis para o planejamento e para a implantação de práticas e de manejos que favoreçam a conservação do solo e da água.

Headwater catchments store valuable resources of quality water, but their hydraulic response is difficult to assess (model) because they are usually deprived of monitoring stations, namely hydrometric stations. This issue becomes even more pertinent because headwater catchments are ideal for the practice of conjunctive water resources management involving the supply of towns with groundwater and surface water, a solution that can be used to mitigate overexploitation of groundwater resources in densely urbanized and populated areas. In this study, a stepwise approach is presented whereby, in a first stage, a gauged basin was modeled for stream flow using the JAMS J2000 framework, with the purpose to obtain calibrated hydraulic parameters and ecological simulated stream flow records. Having validated the model through a comparison of simulated and measured flows, the simulated record was adjusted to the scale of an ungauged sub-basin, based on a new run of JAMS J2000 using the same hydraulic parameters. At this stage, a second validation of modeled data was accomplished through comparison of the downscaled flow rates with discharge rates assessed by field measurements of flow velocity and water column height. The modeled basin was a portion of Jequitiba River basin, while the enclosed sub-basin was the Marinheiro catchment (state of Minas Gerais, Brazil). The latter is a peri-urban watershed located in the vicinity of Sete Lagoas town, a densely urbanized and populated area. This town uses 15.5 hm3 year−1 of karst groundwater for public water supply, but the renewable resources were estimated to be 6.3 hm3 year−1. The impairment between abstraction and renewable resources lasts for decades, and for that reason the town experiences systemic water table declines and sinkhole development. The present study claims that the storage of quality water in the Marinheiro catchment, in a dam reservoir, would help alleviate the depletion of groundwater resources in the karst aquifer because this catchment could deliver 4.73 hm3 year−1 of quality surface water to the municipality without endangering ecologic flows. The construction of a small dam at the outlet of Marinheiro catchment could also improve aquifer recharge. Presently, the annual recharge in this catchment approaches 1.47 hm3 but could be much larger if the small dam was installed in the water course and the captured stream water managed properly.

RESUMOA água é um recurso natural essencial ao desenvolvimento humano e às suas atividades. Contudo, a sua disponibilidade tem sido amplamente discutida em vários países do mundo, sobretudo no Brasil. A escassez deste recurso, associada à elevada degradação dos cursos d'água e a grande demanda para os usos múltiplos, tem levado à cenários de conflitos pelo uso da água, em locais onde sua disponibilidade é inferior à demanda. Objetivou-se avaliar e espacializar a disponibilidade hídrica da Bacia Hidrográfica do Rio Manso, MG. A execução da metodologia compreendeu quatro etapas principais: (i) obtenção dos dados; (ii) processamento dos dados de outorga de usuário; (II) exportação das bases de dados para ambiente SIG; (iv) cálculo da demanda hídrica e espacialização da disponibilidade. Foram identificados na bacia 215 pontos de captação de água superficial com processos de outorga vigentes. Estes representam uma demanda de 0,1831 m³/s associada a 15 usos distintos, sendo os principais: irrigação, consumo humano, dessedentação de animais, aquicultura, mineração e lavagem de veículos. Embora a maior parte do curso d'água esteja em estado de disponibilidade hídrica, alguns pontos apresentaram-se em estado de atenção, apontando a necessidade de uma análise integrada a bacia, de forma a garantir a sua sustentabilidade. Palavras-chave:Gestão recursos hídricos, ZAP, Demanda hídrica. DIAGNOSIS OF WATER AVAILABILITY IN THE HYDROGRAPHIC BASIN OF THE RIO MANSO -MG, BRAZIL ABSTRACTThe water is an essential natural resource to human development and its activities. Nevertheless, its availability has been widely discussed in several countries in the world, especially in Brazil. This resource shortage, associated with the watercourses degradation and the increased demand for multiple usage, has led to conflict scenarios over the water usage where its availability is lower than the demand. Objectived evaluate and spatialize the water availability at the Rio Manso's watershed in MG. The implementation of the methodology included four main steps: (I) data collection; (II) water usage bestowal data processing; (III) databases export into GIS environment; (IV) water demand calculation and water availability