Evaluation of Hydrogeological Quality of Various Implementations of Riga City Water Supply System

Drinking water for Riga city is provided by the groundwater well field “Baltezers, Zakumuiza, Rembergi” and by the Daugava river as a surface water source. Presently (2016), it amounts to 122 thous.m3/day and both sources do not exploit even half of their power. Therefore, in future it seems reasonable to use only groundwater, because the river water is of low quality and its treatment is expensive. Scientists of Riga Technical University by using hydrogeological model of the well field “Baltezers, Zakumuiza, Rembergi” proved that its capacity covers the demand for 120–122 thous.m3/day of drinking water in Riga until 2030. Therefore, it is possible not to exploit the Daugava river as the water source. The research was done as to the request of the company “Aqua-Brambis”. The company asked to evaluate hydrogeological properties of several versions of water supply of Riga city. It was necessary to check the stability of syphon type systems that extract the groundwater for the city under the conditions of their increased productivity. It was also proved that the syphons may be replaced by a pumping station. Then the number of exploitation wells considerably decreases. The impact of expenses related to reconstruction of the wellfield and the water distribution network was not considered. The publication may be of interest for the specialists dealing with problems of water supply for large cities.