Dinâmica dos aquíferos da região do bairro Pedra Noventa em Cuiabá-MT

Abstract

In the district of Pedra Noventa located in the southeastern portion of the Cuiabá city the more shallow groundwater aquifer is intensively exploited by shallow and deep wells. In this area there are many cesspools exposing aquifers to contamination, intensified during the rainy season. The overall objective is to evaluate the influence of rainfall, topography, soil and rock on the aquifers. We measured the temperature, relative humidity and precipitation over a hydrological year. We made the geological and morphopedologic maps, delimiting homogeneous areas associated with the hydric behavior. The thickness of the aquifer rocks has been detailed in two areas, using inductive electromagnetic methods and geoelectric (VES and WE). The geophysical results indicated favorable locations for drilling for deep wells. Were performed two boreholes, one in each area before drilling, with withdraw of testimony to detail the structural and lithological profile. The hydrodynamic parameters were obtained starting from production testing of the aquifer in six wells tubular, using the methods and Newman Theis. The dynamics of the aquifer were calculated from the monthly monitoring of the static level in 30 shallow wells and 25 deep wells. Geological mapping identified four units in the area: the Rio Coxipó Formation; Miguel Sutil Formation; Pantanal Formation and Alluvial Deposits. The electromagnetic inductive method mapped anomalous zones with apparent conductivity greater than 16 mS/m, associated with metadiamictito saturated sandy matrix. The aquifer formed by the Rio Coxipó Formation occurs in free form and confined. The coefficient of storage is supported for the free and confined aquifer. The groundwater flow in the area is preferably for SE and subordinate to E and S, and follows the topography of the land. The integration of precipitation, and geology morfopedologia allowed to describe the behavior of aquifers in the six compartments morphopedologic. Surface Planed aquifer does not occur in the soil, rainwater recharges the mantle of alteration forming the phreatic aquifer. Surface Ramp allows the harness ferruginous infiltration of rainwater and develops a groundwater flow towards areas of lower altitude. Wet Fields with Mounds form suspended aquifers on the cuirass ferruginous. The Extensive Valleys receive subsurface flows. On the Terrace in the groundwater aquifer recharge is direct. In the Hills and Medium Morrotes lag occurs in response static level in relation to rainfall.