Scientific Investigations Report 2014–5113
The hydrogeology and water quality of the Chakari Basin, a 391-square-kilometer (km2) watershed near Kabul, Afghanistan, was assessed by the U.S. Geological Survey and the Afghanistan Geological Survey to provide an understanding of the water resources in an area of Afghanistan with considerable copper and other mineral resources. Water quality, chemical, and isotopic samples were collected at eight wells, four springs, one kareze, and the Chakari River in a basin-fill aquifer in the Chakari Basin by the Afghanistan Geological Survey. Results of water-quality analyses indicate that some water samples in the basin had concentrations of chemical constituents that exceeded World Health Organization guidelines for nitrate, sodium, and dissolved solids and some of the samples also had elevated concentrations of trace elements, such as copper, selenium, strontium, uranium, and zinc. Chemical and isotopic analyses, including for tritium, chlorofluorocarbons, and carbon-14, indicate that most wells contain water with a mixture of ages from young (years to decades) to old (several thousand years). Three wells contained groundwater that had modeled ages ranging from 7,200 to 7,900 years old. Recharge from precipitation directly on the basin-fill aquifer, which covers an area of about 150 km2, is likely to be very low (7 × 10-5 meters per day) or near zero. Most recharge to this aquifer is likely from rain and snowmelt on upland areas and seepage losses and infiltration of water from streams crossing the basin-fill aquifer. It is likely that the older water in the basin-fill aquifer is groundwater that has travelled along long and (or) slow flow paths through the fractured bedrock mountains surrounding the basin. The saturated basin-fill sediments in most areas of the basin are probably about 20 meters thick and may be about 30 to 60 meters thick in most areas near the center of the Chakari Basin. The combination of low recharge and little storage indicates that groundwater resources are likely to be limited. Groundwater use in the villages of the basin is generally supplied by hand-pumped wells, whereas agricultural needs are met by surface-water flows. New or increased water uses in the basin, or activities that may affect water quality, should be carefully evaluated to avoid affecting existing uses.
First posted August 19, 2014
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Mack, T.J., Chornack, M.P., Flanagan, S.M., and Chalmers, A.T., 2014, Hydrogeology and water quality of the Chakari Basin, Afghanistan: U.S. Geological Survey Scientific Investigations Report 2014–5113, 35 p., http://dx.doi.org/10.3133/sir20145113.
ISSN 2328-031X (print)
ISSN 2328-0328 (online)
Water Quality, Chemistry, and Isotopes
Summary and Conclusions
Appendix 1. Physical Properties, Nutrient, Bacteria, and Major Ion Water-Quality Data for the Chakari Basin, Afghanistan
Appendix 2. Trace-Element Water-Quality Data for the Chakari Basin, Afghanistan
Appendix 3. Inorganic and Anthropogenic Tracer and Dissolved Gas Data for the Chakari Basin, Afghanistan