Navegando por Autor "Hirata, Ricardo"

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Determining groundwater availability and aquifer recharge using GIS in a highly urbanized watershed.
(2020) Conicelli, Bruno Pirilo; Hirata, Ricardo; Galvão, Paulo Henrique Ferreira; Luiz, Mariana Bernardino; Simonato, Mateus Delatim; Abreu, Marcio Costa; Aranda, Nataly; Terada, Rafael
Extensive urbanized areas, characterized by waterproofed soils, increase runoff, which reduces the rainwater infiltration into the ground. However, water, sewer, and rainwater distribution systems leak, as there is excess irrigation in green areas, resulting in anthropic recharging in urban aquifers larger than in rural areas with equivalent climates. This scenario occurs in the Upper Tietê Watershed (UTW), an area of 5,868 km2 that drains the principal rivers of the Sao ˜ Paulo’s metropolitan region in Brazil, where groundwater plays a complementary role for domestic, industrial, and agricultural supplies, totalizing extraction rates higher than 11 m3 /s. In this paper, a Geographical Information System (GIS) was established to assess regional groundwater availabilities using adaptations of classic recharge methods such as soil water budget calculations and estimation of minimum sustainable river flow. For this, a surface runoff map, based on soil and slope terrain data, was evaluated using the information on water and sanitation infrastructure and meteorological data. We found that recharge in urban areas (with water and sewer mains) was 437 mm/yr and 106–407 mm/yr in rural areas. Considering the need to maintain a minimum historical flow of 20 m3 /s in the hydrographic basin of the Tietê River, the total exploitable groundwater is 33 m3 /s. The compilation of various GIS methods can help decision-makers develop alternative water security management plans in complex urbanized-regions such as in the metropolis of São Paulo.
Determining groundwater availability and aquifer recharge using GIS in a highly urbanized watershed.
(2021) Conicelli, Bruno Pirilo; Hirata, Ricardo; Galvão, Paulo Henrique Ferreira; Luiz, Mariana Bernardino; Simonato, Mateus Delatim; Abreu, Marcio Costa; Aranda, Nataly; Terada, Rafael
Extensive urbanized areas, characterized by waterproofed soils, increase runoff, which reduces the rainwater infiltration into the ground. However, water, sewer, and rainwater distribution systems leak, as there is excess irrigation in green areas, resulting in anthropic recharging in urban aquifers larger than in rural areas with equivalent climates. This scenario occurs in the Upper Tietˆe Watershed (UTW), an area of 5,868 km2 that drains the principal rivers of the Sao ̃ Paulo’s metropolitan region in Brazil, where groundwater plays a complementary role for domestic, industrial, and agricultural supplies, totalizing extraction rates higher than 11 m3 /s. In this paper, a Geographical Information System (GIS) was established to assess regional groundwater availabilities using adaptations of classic recharge methods such as soil water budget calculations and estimation of minimum sustainable river flow. For this, a surface runoff map, based on soil and slope terrain data, was evaluated using the information on water and sanitation infrastructure and meteorological data. We found that recharge in urban areas (with water and sewer mains) was 437 mm/yr and 106–407 mm/yr in rural areas. Considering the need to maintain a minimum historical flow of 20 m3 /s in the hydrographic basin of the Tietˆe River, the total exploitable groundwater is 33 m3 /s. The compilation of various GIS methods can help decision-makers develop alternative water security management plans in complex urbanized-regions such as in the metropolis of Sao ̃ Paulo.
Geologic conceptual model of the municipality of Sete Lagoas (MG, Brazil) and the surroundings.
(2016) Galvão, Paulo Henrique Ferreira; Hirata, Ricardo; Cordeiro, Arnaldo; Barbati, Daniela; Peñaranda, Jorge
The study area is located in the state of Minas Gerais, Brazil, among the municipalities of Pedro Leopoldo, Matozinhos, and Sete Lagoas, with Velhas River as the eastern boundary. It is located in the São Francisco Craton, where carbonated argillo-arenaceous sediments are emplaced giving origin to the Bambuí Group, in the São Francisco Basin. Despite the geological knowledge previously developed, the region needs work on integration and detailing of such information. For this reason, the main objective was to contribute to the quality of the geologic cartography, the spatial distribution, and the structural framework geometry. Thus, geologic mapping, aerial photography interpretation, and evaluation of 270 lithologic well profi les were carried out. It was possible to establish a new geologic perspective of the region by obtaining the detailed geologic map of the municipality of Sete Lagoas, 14 geologic cross sections, and a geologic conceptual model. The study showed that the area is within a basin border, presenting a geometry conditioned by horst and graben system controlled by faulting. This structural feature displaced stratigraphic sequences positioning them side by side with lithologic sequences with different ages.
Influências urbana, industrial e climática na superexplotação do aquífero cárstico no município de Sete Lagoas (MG).
(2022) Schuch, Camila Santos; Galvão, Paulo Henrique Ferreira; Melo, Marília Carvalho de; Galvão, Paulo Henrique Ferreira; Bacellar, Luis de Almeida Prado; Hirata, Ricardo
Aquíferos cársticos, quando explotados intensivamente, podem ter como consequência efeitos adversos diretos, como subsidência de terrenos, secas de nascentes e lagoas, e contaminação de água, e indiretos, como problemas ambientais, e instabilidades socioeconômica e política. No município de Sete Lagoas (MG), esses efeitos relacionados à explotação intensiva são observados há anos, e muitos deles estão se intensificando. O objetivo deste mestrado é analisar a influência das variações urbana, industrial e climática no comportamento do aquífero cárstico durante os últimos 40 anos (1980-2020) para confirmar se há superexplotação do aquífero, e desde quando essas influências atuam. Por meio da análise de dados de órgãos públicos e de trabalhos acadêmicos, foi determinado que o município explota, via poços tubulares, volumes acima da recarga média do aquífero desde a década de 2000. A partir da década de 1980, houve um aumento considerável de poços, muitos deles locados desordenadamente no município, devido às expansões urbana e industrial que resulta em um aumento na demanda hídrica. Esses poços estão concentrados em duas regiões (central urbana e polo industrial) onde há cones de rebaixamento com áreas de influência quilométricas (29 km² e 77 km², respectivamente), alterando o comportamento do aquífero de confinado para livre nessas localidades. Nessas regiões também concentram as subsidências de terrenos, além da diminuição ou secamento de lagoas (e.g. Grande, do Matadouro e Paulino). Dados referentes à última década indicam que a explotação via poços tubulares (73,9 Mm³/ano) já excedeu a recarga máxima do aquífero de 72,4 Mm³/ano. A partir de dados do censo demográfico, foi estimada a clandestinidade no município, que equivale a cerca de 67% dos poços, estes sem nenhum tipo de informação ou controle de uso. A recarga média do aquífero (56,1 Mm³/ano) corresponde a 12% da precipitação média da região. As tendências climatológicas de diminuição da pluviometria e aumento da temperatura indicam a probabilidade de recargas menores do aquífero. Áreas com taxa de recarga muito baixa (1-5%) equivalem a 77% do território, enquanto 17% possui taxas altas ou muito altas (35-75%). Considerando-se esses fatos, Sete Lagoas enfrenta um estado de superexplotação do aquífero cárstico e que pode se agravar futuramente.
Nitrate contamination in Brazilian urban aquifers : a tenacious problem.
(2020) Hirata, Ricardo; Cagnon, Fabiana Alves; Bernice, Aline Michelle; Maldaner, Carlos Henrique; Galvão, Paulo Henrique Ferreira; Marques, Carlos Henrique Gil; Terada, Rafael; Varnier, Claudia Luciana; Ryan, M. Cathryn; Bertolo, Reginaldo Antonio
This study follows the geochemistry of nitrogen in a Cretaceous and unconfined sedimentary aquifer in the city of Urânia (Brazil) over 20 years. Although the sewer network was built in the 1970s, the nitrate contamination problem (>45 mg/L-NO3 −) persists to this day. The oldest urbanization areas located in the north of the city initially used cesspits for wastewater and currently present the highest nitrate concentrations (>120 mg/L-NO3 −), with the plume reaching the deeper aquifer portions (up to 100 m). The contamination is not as dramatic in the south part of the city, where urbanization including installation of the sewage network with PVC pipes that are more resistant to leak than the old ceramic networks occurred after 1985. Based on the constructive well profiles, three hydrogeochemical zones were established: shallow (60 m), with 17 mg/L-NO3 −. The current total nitrate mass in the aquifer exceeds 731 kg-NO3 −. Numerical flow (Modflow) and transport (MT3D) model scenarios support the hypothesis that the nitrate contamination is caused by substantial infiltration of nitrogen through the cesspits until the 1970s, but after the 1990s, leaks from the sewer network should be responsible for the maintenance of the recently observed high concentrations of nitrate.
Recharge sources and hydrochemical evolution of an urban karst aquifer, Sete Lagoas, MG, Brazil.
(2017) Galvão, Paulo Henrique Ferreira; Hirata, Ricardo; Halihan, Todd; Terada, Rafael
The current water supply for the city of Sete Lagoas, Brazil, is almost entirely groundwater from the Sete Lagoas Karst Aquifer, with a small contribution from a fractured-basement rock aquifer. Characterizing the hydrogeologic processes is important for proper water resource management, avoiding contamination and other future issues. The main goal of this study is to identify active hydrogeological processes, such as possible surface– ground water interactions, sources of recharge, and the hydrochemical evolution of groundwater through the use of stable isotopes 18O and 2H and major ion data. The groundwater samples were collected from the karst aquifer (central urban area) and from the fractured aquifer (southern part of the city). Surface water samples were collected from the seven main lakes, and rainwater was sampled over a period of one year. The stable isotope results indicated the groundwater origin is directly from local precipitation, having a limited recharge period, and locally receiving surface water contributions. Groundwater quality in the central urban area may be influenced by surface water infiltration where the karst aquifer is in contact with overlying unconsolidated sediments. Some samples with nitrate concentration of 10 mg/L or higher indicates the natural composition of the groundwater has been altered by urban sewage contamination. The highest concentrations of major ions were found in the central region, where the most karstified area from the Sete Lagoas Formation is located. These data suggest a longer residence time for this water, indicating more mineralization, in accordance with the geological information.
Transmissivity of aquifer by capture zone method : an application in the Sete Lagoas Karst aquifer, MG, Brazil.
(2017) Galvão, Paulo Henrique Ferreira; Halihan, Todd; Hirata, Ricardo
Transmissivity is an important hydraulic parameter to determine the amount of water passed horizontally across a given saturated thickness of an aquifer. The techniques to quantify this parameter, such as grain size analyses or pumping tests, can have limitations of time/spatial scale, viability, or economically. One technique that can be used, but little adopted, is the capture zone analysis. In this paper, capture zone analytical equations were used to estimate transmissivity values in order to verify the effectiveness of this methodology as alternative in situations where other traditional methods present implementation difficulties. The results were compared with field data estimated by aquifer tests conducted in the same region. A sensitivity analysis was also performed to identify possible discrepancies between the analytical and field data results. The aquifer studied was the Sete Lagoas Karst Aquifer in the urban region of the municipality of Sete Lagoas, Brazil. The method proved to be a viable and economical tool, where the analytical values compared to the aquifer tests showed similarities, being confirmed by a sensitivity analysis. However, a reliable potentiometric surface map, which enables the identification of the parameters for analytical capture zone equations, is needed.