FenixEdu™

Dissertação

{pt_PT=Semarang, and its underground problems: Spatiotemporal hydrochemical assessment of shallow groundwater in Semarang, Indonesia} {} EVALUATED

Detalhes: {pt_PT=Para garantir água potável e saneamento para todos até 2030 (UN-SDG6), os países têm que investir em infraestruturas adequadas, melhorar as condições de higiene e garantir um saneamento adequado. Semarang é uma cidade em vias de desenvolvimento localizada na ilha de Java, Indonésia, e que enfrenta inúmeros desafios ambientais, principalmente relacionados com a qualidade dos recursos de água subterrânea. Esta investigação estuda o aquífero superficial de Semarang que tem vindo a apresentar sinais do impacto do rápido desenvolvimento da cidade com o objetivo de caracterizar a qualidade da água subterrânea combinando métodos de análise hidrogeoquímica e estatística multivariada das amostras de água subterrânea recolhidas em 2017 e 2019 com um levantamento sobre os usos e práticas da água dos proprietários dos poços onde foram recolhidas as amostras. Os resultados confirmam dois tipos de poluição, uma de origem difusa (intrusão salina) encontra-se nas áreas industriais devido às práticas insustentáveis de captação de água subterrânea; e, outra de origem pontual (nitrato, nitrito e E. Coli) relacionado com a falta de rede adequada de saneamento. Esta investigação verificou ainda que a água subterrânea captada a partir de poços escavados privados muitas vezes não está em boas condições para consumo humano, concluindo que a qualidade da água subterrânea influencia os usos e práticas dos proprietários de poços escavados na baixada de Semarang, uma vez que estes acabam por não usar a água subterrânea como fonte de água potável e em alternativa recorrem a origens de água potável, como a água engarrafada ou a água tratada da torneira., en_GB=To ensure clean water and sanitation for all by 2030 (UN-SDG6) countries need to invest in adequate infrastructure, encourage hygiene, and good sanitation facilities. Semarang is a developing city located in Central Java, Indonesia, which is experiencing all kinds of environmental challenges mostly of which relate to water. This research focuses on the unconfined aquifer of Semarang lowlands, since it is suspected to be impacted by the current rapid development of the city. This development is leading to an increase of anthropogenic activities, and these are suspected to have an impact to the unconfined aquifer. This research assesses the current state of the unconfined aquifer, via a hydrogeochemical and multivariate statistics analysis of the collected groundwater samples from Semarang lowlands in 2017 and 2019, and a survey on water uses and practices of the same dug well samples. This analysis results to identify two kinds of pollution: diffuse and point-source pollution. The first one is found in the vicinities of industrial areas, and is characterised by seawater intrusion. The latter is found in the form of nitrate and nitrite in some of the 30 dug wells, including E. coli is found in all 30 dug well samples, ranging from 1 to 5 MPN/L. Seawater intrusion is reflected in the water-type composition of dug wells, and there are two water types characterising Semarang lowlands: Ca-Na-HCO3 (with varying concentrations of Ca, Na) and HCO3, (with a low concentration of Cl). The first group is mainly found near the higher planes. The second water type is characterised as Na-Cl-HCO3 (with a low concentration of Ca and higher mineralization). This second group is only found in the vicinities or inside industrial areas of Semarang lowlands. Both years were brackish, but varying in percentage, fresh-brackish with a 13.3% in 2019 and 3.3% in 2017. The previous findings are supported by the statistical analysis with a positive correlations in the Pearson analysis between sea-water components, such as Cl vs SO4 (r = 0.59 in 2019 and r = 0.63 in 2017). At the same time a positive relationship between magnesium and chloride is observed in 2017; where Mg has higher concentrations due to seawater mixing and possibly cation exchange (r = 0.4 in 2019 and r = 0.93 in 2017). PCA results not only evidence but support the previous findings on the hydrochemical variables which play a major role, and therefore are influential, to the groundwater quality of the area. Point source pollution is also evidenced in statistical analysis, where in the PCA results of 2019 show a correlation between nitrite and ammonium, but this is different for 2017 results. However, these compounds remain highlighted in PC4 and PC5. The location of the contaminated samples from nitrate and nitrite are located in the neighbouring areas of industrial zones, being clearly evidenced by the 2019 dug wells. In this research it is discussed the presence and origins of these nitrogen-compounds; by the industrial wastewater, and/or sanitary infrastructure of Semarang lowlands. Throughout the discussion it is put to debate the relatable causes of these existing pollutions, since it is suspected that seawater intrusion links to the unsustainable groundwater abstraction practices by industries of the area, and point-source pollution relates to the poor sanitation infrastructures of the city. Furthermore, this research concludes that the groundwater accessible from private dug wells is often not of good condition for human consumption. This research understands that the quality of groundwater has an influence on the uses and practices of the dug well owners of Semarang lowlands. By discarding the end user habit of using groundwater as a drinking source, and move to potable water sources such as bottled water, or treated water from the tap. }
Keywords: {pt_PT=água subterrânea, intrusão salina, poluição difusa, Semarang, Indonésia, en_GB=underground water, seawater intrusion, diffuse pollution, Semarang, Indonesia}

Discussão: novembro 17, 2020, 11:30