Assessing changes in groundwater quality of uppermost aquifers over time

Abstract

Summary To assess and forecast the groundwater status, it is necessary to establish trends in the water quality. In Ukraine, the network of the State groundwater monitoring observation wells is extremely insufficient, and there are very few monitoring data. In addition, the hydrochemical characteristics of individual water intakes may often not reflect general trends in quality changes within large hydrogeological or hydrological regions. Under such conditions, to assess the groundwater status and changes in its quality, it is advisable to use information obtained in the process of various geological works, including hydrogeological exploration and hydrogeological mapping. The collected hydrogeological information was analyzed using geoformation technologies. To assess temporal changes in the quality of groundwater, a comparison of the hydrochemical characteristics obtained from the results of the hydrogeological study of groundwater in the course of exploration work in the 60–70s of the last century and the hydrogeological study of the previously mapped areas in 2000–2010 was made. To assess the quality of groundwater, the methodological approaches of the National Standard of Ukraine “Sources of centralized drinking water supply. Hygienic and environmental requirements for water quality and sampling rules” (DSTU 4808: 2007) were used. The standard provides for the division of groundwater by chemical composition into four classes: excellent, good, satisfactory and mediocre. Comparison of data for different periods clearly showed the intensive groundwater pollution process in unconfined aquifers. The maps compiled for different time periods showed the scale and irreversibility of changes in the chemical status of groundwater in the Quaternary aquifers. The use of water quality criteria of the National standard of Ukraine SSTU 4808:2007 has shown a steady tendency for water from excellent, desirable, as well as good, acceptable water quality, to satisfactory, acceptable water quality. The assessment will be used in the process of improving the network of observation wells for groundwater monitoring in the Dnipro River basin.