Estudo do aquífero costeiro na zona de Chuabo Dembe usando a broca de recolha

Abstract

The Chuabo Dembe neighborhood is located on the coast. One of the biggest problems that has been recorded is the capture of drinking water in wells combined with saline intrusion influenced by the Bons Sinais estuary. With the objective of characterizing the coastal aquifer of Chuabo Dembe in the possibility of improving the techniques of extraction and the use of water from the coastal aquifer of Chuabo Dembe, two collection drills were built with the aim of opening research holes in which a sensor was placed. pressure and salinity for 15 days. To relate to the tide variation, a tide gauge (TWR-2050) was anchored in the Bons Sinais estuary, calibrated at the same frequency as the sensors placed in the research holes. In addition, sediment samples were collected depending on the depths of the research holes. Results found indicate that the coastal aquifer of Chuabo Dembe consists of very fine sand, clay and silt, and organic matter and organism fragments are also found in its composition (shells and plants), it has low and high permeability, porosity that reduces the as it approaches the estuary due to the greater presence of clay in its geological structure. In terms of water movement, the Chuabo Dembe aquifer has an average conductivity of 7.26 m/s, capacity to transmit water is 10.2 m/d on average, the hydraulic potential shows that the aquifer drains water towards the estuary and for times from the estuary to the coast and this flow variation varies according to hydraulic head and tidal influences. On average, the water table varies by 1.2m during the tidal cycle. It presents yellowish water in the region closest to the estuary and cloudy with a smell due to the presence of organic matter. Regarding the hardness of the water in the first hole, the use of water is not recommended due to the higher concentration of calcium carbonate.