Physical and geochemical properties of groundwater in Kungälv municipality

Abstract

The topic of groundwater levels and quality is relevant to many topics, such as agriculture, drinking water access, and geotechnical engineering; especially when considering the dramatic changes wrought as a result of the greenhouse effect. This study is an attempt to evaluate these questions at a local scale, namely by studying the groundwater found in Kungälv municipality. In evaluating these questions, the decision was made to divide the study into three phases: one pertaining to charting physical groundwater properties, one charting chemical characteristics and looking for pollutants, and one investigating the local viability of other methods to investigate groundwater levels. The results for the survey of physical properties revealed a general groundwater depth of 0-2 m across the municipal territory. In total, seven functioning groundwater observation wells could be found in the survey, excluding those in Dösebacka; however, the true number of pipes are likely more, though their location, condition, and visual appearances are unknown at this point due to time constraints. From the chemical analyses performed in the municipality, all water samples gathered from lowlands or depressions with connections to a larger stream were dominated by bicarbonate, while those outside of these had a distinct lack of bicarbonate, which may vary with flow distance and availability of biological refuse. In addition, the results indicate that sodium content increases closer to salt water and in the absence of quick clay. Lastly, the low concentration of tritium and decent levels of metals detected at almost all sampled sites reveal that the water is relatively safe to utilize, though more research should be performed to ascertain the veracity of the latter claim. As for the alternative surveying methods, it was discovered that all of the evaluated methodologies (surface water, ground-penetrating radar (GPR), and dry crustal clay) were accurate, though the latter was of limited practical use. The method that would be optimal, based on the sampled data, would be a combination of surface water measurements and ground-penetrating radar in long continuous profiles, where the surface water would provide a reliable reference point from which accurately detecting the water table in a clay layer would be facilitated.