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The purpose of this paper is to analyze the changes of the characteristics of the study area caused by human influence and the reduction of flow rates with time, in Água Limpa stream basin, Jequitinhonha Valley of Minas Gerais, Brazil.

The study area is a typical arid zone in the northeast of Minas Gerais, Brazil. Field observations, collection and analyses of precipitation, evaporation, temperature and flow rate data were the main approaches used in this study. The data cover the last 50 years, including aerial photographs and satellite images of different dates. The stream flow rate has decreased in the region of the Jequitinhonha valley in the last decades, in particular during draught periods (base flows), with serious social‐economic and environmental consequences. The increase in stream intermittence is responsible for rural exodus to other parts of the country, mainly to São Paulo state. The study presented provides decision makers with important information that can assist them in making objective decisions relational this problem.

The research shows that the forest cover has declined, the agricultural and pasture cover have decreased and the deforestation areas have grown. These changes resulted in a spatially diverse landscape with implications in the flow rate, and consequently, in the social‐economic condition of the region considering the high rate of emigration.

The expected results of this study will be of great importance, because the clarification of the factors addressed in this project will allow progress in the understanding of the reduction of flow rates. This reduction has been occurring in the Jequitinhonha Valley and also in almost all Brazilian rivers.

This paper is original and reports the main causes for decreasing of the stream flow rate in the region of the Jequitinhonha valley in Brazil.

Of the numerous hydrogeochemical river‐water transformations provoked by intense and irrational soil practices, heavy metal contamination by agrochemical usage is the most worrisome. Long‐term metal accumulation can be transported by rainwater, during storms, contaminating rivers. Data on this type of contamination are still scarce, principally in developing countries, such as Brazil. This paper aims to evaluate the influence of agricultural activities on the hydrogeochemistry of the Paracatu River's sub‐basins.

From a total of 77 points along three sub‐basins, water samples were taken for heavy metal and trace element analyses using spectrometry of atomic emission through plasma (ICP‐OES, Spectro Ciros CCD). The principal water‐quality parameters, such as pH, turbidity, conductivity, oxi‐reduction potential, total dissolved solids (TDS), temperature and dissolved oxygen were measured in situ.

By incorporating a small drainage area at the monitoring points, it was possible to perceive agriculture's influence (in the form of heavy metal contamination from fertilizers and pesticides) on the water courses.

Although the research was carried out at a total of 77 points for water collection, data are from just one wet season, and need to be repeated.

The results demonstrate a need for monitoring the areas involved with agricultural activities, not only along the main river, but also along small streams that compose the Paracatu Basin.

There is no published literature on this subject regarding the three studied basins.

The purpose of this research is to determine the major environmental impacts and, especially, to evaluate the geochemical characteristics of water of the lakes formed in abandoned quarries of ornamental rock of the Campo Belo Metamorphic Complex.

To do so, 12 quarries were chosen to be studied. They were mapped in a detail scale and their rocks were described and sampled for petrography analysis. Whenever present, the lakes were evaluated too. In situ measurements included pH, Eh, conductivity, resistivity, total dissolved solids and temperature. Water samples were collected to determine alkalinity, sulfates, chlorates, turbidity, suspended sediments and the concentrations of major and trace elements using the ICP‐OES.

Abandoned open‐pit mining operations have resulted in the creation of numerous pit lakes. About 90 per cent of the quarries visited and studied were abandoned or interdicted by environmental organs, what will probably lead to its subsequent abandonment. The quarries Borges and Gêmeos were two quarries of the abandoned quarries in the region, which has a lake formed in its trench. Gêmeos and Borges pit lakes analytical data shows clear correlation between the chemical compositions of the solute and the geological characteristics of the quarries. In spite of the differences found, the results showed a relatively quality water according to Brazilian legislation control values.

This was the first study done of pit lakes formed in abandoned ornamental rock quarries of Campo Belo Metamorphic Complex/Minas Gerais – Brazil. This research provides a better understanding of the gneisses pit lakes hydrogeochemistry, a subject neglected in scientific literature.