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Hydrogeology of the Kabul Basin (Afghanistan), part II: groundwater geochemistry
Georg Houben & Torge Tnnermeier & Naim Eqrar &
Thomas Himmelsbach
Abstract Shallow groundwater is the main source for drinking water in Kabul, Afghanistan. It comes from a multitude of shallow hand-pumped wells spread over the whole city area. The groundwater is characterised by slightly oxic redox conditions. Interactions with aquifer carbonates lead to near-neutral pH and high degrees of hardness. The mostly negative water budget of the Kabul Basin is the result of strong evaporation which leads to an increase in salt and also of some undesirable constituents, e.g. borate. Several years of drought have aggravated this problem. The shallow groundwater in the city has received tremendous amounts of pollution due to a lack of proper waste disposal and sewage treatment. Common indicators are elevated concentrations of nutrients such as nitrate and faecal bacteria. The high infant mortality can at least partially be attributed to the insufcient water hygiene. Acid generated during the mineralisation of the wastewater is hidden due to the strong pH buffering capacity of the groundwater system. Redox and pH conditions preclude signicant mobilisation of trace metals and metalloids.
Keywords Afghanistan . Urban groundwater . Arid regions . Infant mortality . Hydrochemistry
Introduction
The inhabitants of Kabul, Afghanistan (Fig. 1) are largely dependent on shallow groundwater for their drinking water supply. Because of an extended drought period (2001 2005) and the destruction of the infrastructure as a result of wars and civil wars, groundwater is now a scarce resource. Barely 20% of the inhabitants are connected up to the central water supply system. Consequently, the city has thousands of shallow hand-pumped wells which supply the drinking water of the majority of the population. Due to a massive inux of returning refugees after the demise of the Taliban regime, Kabuls population has increased sharply.
Sewage is largely disposed of in countless domestic drainage pits and shallow open sewage channels along the streets of Kabul. Therefore it is likely that the shallow aquifers are contaminated by inuxes of contaminants. This probably contributes to the high infant mortality rate which is largely attributable to water-borne diseases (UNICEF 2008). As part of a project nanced by the Foreign Ofce of the Federal Republic of Germany,...