Groundwater, vulnerability

Groundwater vulnerability maps, based on a regional assessment using an index-based system, can be used as a screening tool to rapidly assess the relative scale of impacts arising from pressures. They may be useful for assessing whether ground-water bodies are at risk from pollution sources at initial characterisation. 

In the special case of rivers flowing across shallow aquifers, groundwater vulnerability to percolation of pollutants carried out by rivers is determined by two factors ... 

In the case of lakes overlying shallow aquifers, die groundwater vulnerability to polluted lake water is determined in a similar way as for rivers often, however, the vertical hydraulic gradients tend to display a greater stability through time in these cases. 

Hiscock, K.M., Lovett, A.A., Brainard, J.S. and Parfitt, J.P. 1995. Groundwater vulnerability assessment two case studies using GIS methodology. Quarterly Journal Engineering Geology, 28,179-194. 

Groundwater is vulnerable to pollution by chemicals carried by rainwater, leaching from waste sites or from waste water carrying industrial or agricultural effluent. Treatment of drinking water may remove some, but not all, of these contaminants. Some polycarbonate or metal water pipes that are lined with epoxy resin lacquers may release bisphenol A. 

Gonsalves CM, Esteves da Silva JCG, Alpendurada MF (2007) Evaluation of the pesticide contamination of groundwater sampled over two years from a vulnerable zone in Portugal. J Agric Food Chem 55 6227-6235... 

Foster, S. S. D. 1987. Fundamental concepts in aquifer vulnerability, pollution risk, and protection strategy. In Vulnerability of soil and groundwater to pollutants, ed. W. Van Duijvenbooden and H. G. van Waegeningh. The Hague TNO Committee on Hydrological Research. 

In order to ascertain the degree of accomplishment of the aforementioned Directive 2006/118/EC in Catalonia (NE, Spain) and better characterise the nature of the contamination of these aquifers by pesticides, a monitoring programme was carried out on various selected hydrological units intended to be among the most vulnerable and relevant ones because of intensive agricultural activity and use for human consumption. The number of aquifers analysed depends more or less on the extension of the groundwater body. Eor example, bodies M46 and M21 present extensions of 18 and 72 km, respectively, and just one and two aquifers of each body were analysed, respectively. In contrast, body Ml8 (Maresme) presents an extension of more than 400 km, and nine different aquifers were analysed. 

Surface water was determined to be more vulnerable than groundwater for most contaminants. SOCs were more common in surface waters, and most of the contaminants that exceeded the MCLs were in surface waters. For VOCs, however, no signihcant difference was found in the number of contaminants exceeding MCLs in ground or surface waters. lOCs were found to be equally common in both ground and surface waters. Many SOCs (pesticides, in particular) were seasonally present. 

Water is a finite and vulnerable natural resource and the bulk of it is stored as saltwater in the oceans [1], For the saltwater to be used for industrial, agricultural or household purposes, an expensive conversion process would be required. Thus, freshwater, because of its purity, is generally used in human activities as opposed to saltwater. It is estimated that only 3% of the world s water supply is fresh water and of this, only a third is available as either surface water or groundwater. Over the years, the world population has been surging upward, while most economies have stagnated. The increase in population has exerted an enormous pressure on the world s limited freshwater supply. It is estimated that... 

It is important to note that groundwater and surface water may act both as pathways (e.g., through percolation through the unsaturated zone, saturated ground-water flow and surface water flow) and as receptors (e.g., vulnerable water abstractions, resources or ecological systems). Evaluation of surface water and groundwater as part of contaminated site investigation studies is, therefore, a major concern. 

Groundwater is abstracted from many different types of aquifers, some of which may be highly susceptible to pollution as a consequence of human activity. The vulnerability of groundwater sources is important when assessing the risks to groundwater posed by various activities, Some aquifers are protected by one or more layers of impermeable material, such as clay, that lie above the saturated zone and that will prevent or retard the transport of chemicals from their sources to the saturated zone. Also, aquifers at certain depths may be protected from chemicals (even from some naturally occurring chemicals) that may be present at other depths in the geological profile. 

Groundwater contamination is most likely where stormwater is discharged into soakaways (e.g. pits filled with rubble to speed transfer to groundwater) or infiltration areas, and where the aquifer is vulnerable. However, in many cases, stormwater is collected in the drainage system, which may discharge into sewers. Stormwater or (when sewer capacity is exceeded) a combination of stormwater and diluted raw sewage may be discharged into surface waters, Box 6,3 summarizes the main risk factors associated with urban runoff,... 

Over 80% of industrial wastes, much of which can be classified as hazardous, are disposed of in landfills. Many chemicals enter the environment directly as a result of accidents, spills, or leakage from industrial facilities and waste disposal sites. In the past, contaminated wastes were buried, burned, or chemically treated in place. These treatments are costly, have limited effectiveness, and are difficult to regulate. Landfill and in situ fixation do not destroy waste, and landfilling only changes the place of residence delaying future liability. Contamination of the environment has placed many of our vulnerable resources (e.g., groundwater, wet lands, fisheries, and agricultural lands) at risk. 

In a few cases, nitrogen pollution affects humans directly. Nitrates pollute groundwater supplies in many farming areas. Nitrogen oxides in the air turn into ozone, harming both vulnerable humans and plant life. 

Unless soils and their parent materials are capable of neutralizing acid precipitation (see Chap. 8) pH values may drop to 4 or less in soil moisture and local surface-waters and groundwaters. Spodosols are among the most vulnerable soils to such acidification (Schecher and Driscoll 1987). Under acid conditions dissolved Al concentrations may be as high as 8 to 10 mg/L from the leaching of aluminous minerals such as kaolinite and gibbsite (cf. Bottcher et al. 1985). The dissolved Al then buffers the pH at acid values because of reactions that include... 

While the Earth s surface is mostly water (78%), it is too saline to be potable. We depend on a small, vulnerable fraction of the Earth s water ( 3%) (Manahan 2004) to sustain our lives and the crops and animals upon which we depend for food and flber. The environmental destruction caused by biological and chemical weapons would first endanger the surface water and subsequently be transmitted to groundwater. The environmental effects of biological and chemical weapons would be catastrophic because we all depend on water. Not only would human life be compromised, but our plant and animal communities would also suffer. 

Vulnerability Assessment and Mapping of Akounq Groundwater Body, Armenia... 

Quantitative assessment of water-table aquifers vulnerability is being carried out when there is risk of bacteriological infechon. This method is based on groundwater downward time-of-travel during which percolated bacteria or polluted water may rich to water table. 

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