Aivars Spalviņš

Hydrogeological Modelling for the Development of Raised Bog Conservation and Restoration Projects

Hydrogeological modelling was carried out within the framework of the LIFE project “LIFE Restore – Management and sustainable use of degraded bogs in Latvia” (project No. LIFE14 CCM / LV / 001103). A stabilizing hydrological regime is one of the important preconditions for successful restoration of degraded bogs. Many practices of regeneration of degraded bogs are known in the world, and most of them relate to the exchange, stabilization or recovery of hydrological regime. It is very common to rebuild, block or eliminate land drainage systems, land elevation planning and building of terraces, as well as many other methods. Most of these techniques are aimed at mitigating the impact of drainage of the bog in order to provide a favourable hydrological environment for the restoration of raised bogs vegetation. Hydrogeological modelling is an important tool that greatly facilitates the development of hydrological regime restoration and stabilization projects for degraded high bogs. Hydrogeological modelling was carried out applying the data provided by hydrogeological model of Latvia LAMO4. Development of the model was supported by the Latvian State Research Program EVIDEnT.

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.