United Nations Population Fund estimated that half of the world's population lived in urban areas in 2008 and projected that by the year 2050, the population living in towns and cities would be up by 68%. Furthermore, half of the world's urban population depends on groundwater as the main source of water supply which puts pressure on groundwater as the urban population grows. The main aim of this research is to estimate the groundwater recharge within urban centres with water table fluctuation (WTF) method and to evaluate physico-chemical quality of groundwater using Wattle Grove area, Sydney, Australia as a case study. The groundwater table depths were continuously monitored on an hourly basis over one year with data loggers installed in the four newly developed boreholes. The groundwater samples were collected on a monthly basis and taken to the university environmental laboratory for physico-chemical analysis. The concept of rainfall-induced groundwater recharge is taken as groundwater recharge caused solely by rainfall while total groundwater recharge is caused by all other factors including rainfall. Both were estimated by considering the wet and dry periods in the year. On average, during the rainy periods, BH1 had the highest recharge per day of 1.67 mm/day while BH4 with 0.28 mm/day was the least. The variation of recharge estimates across the four sites could be attributed to different surface topography, presence of water bodies and underground water movement. In spring and summer season, the groundwater-level response to rainfall shows that BH4 recorded the shortest lag time of 3 days while BH2 recorded the longest time of 14 days. The fastest time is as a result of fissure flow while the longest time is attributed to slow matrix flow. The combined analysis of spring and summer also shows that BH4 has the shortest response time and rainfall has a direct impact on groundwater level fluctuations. For all the four boreholes pH, calcium and potassium concentrations in groundwater were within Australian Drinking Water Guideline (ADWG) and World Health Organisation (WHO) standards. Only BH1 has a high sodium concentration of over 4000 mg/L and a magnesium concentration of 500 mg/L and both exceed the aforementioned guidelines value of (50 - 300 mg/L). Too, the TDS value of BH1 exceeds EPA's guideline value of 1500 - 2600 mg/L and that makes the groundwater unsuitable for irrigation. This indicates that the groundwater may be contaminated by the salt. The source for the salt, at this stage, is unknown. The groundwater from the four boreholes exceeds the turbidity limit of 5 NTU and it cannot be used directly for drinking.
Date of Award | 2019 |
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Original language | English |
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- groundwater
- drinking water
- municipal water supply
- quality
- Wattle Grove (N.S.W.)
- New South Wales
Estimation of groundwater recharge and assessment of groundwater quality in urban landscapes : a case study of the Wattle Grove area
Ezemba, S. N. (Author). 2019
Western Sydney University thesis: Doctoral thesis