POLDER SYSTEM IMPACT ON NATURA 2000 TERRITORIES: A CASE STUDY OF VALGUNDE LATVIA

Abstract

The oversupply of water during the floods and the low soil surface levels determine the difficult ecological, economic, and demographic conditions. It then leads to using agricultural land of different types and intensities and various methods of regulating the water regime: summer polders. Human activity has significantly impacted the ecological processes of the floodplains of the Svete floodplain with extensive amelioration works that have significantly altered the appearance of a natural park. The total area of the natural park Svete floodplain is 931 ha. The Valgunde summer one polder channel is the regulated tributary of the right coast of Lielupe and Mellupite, partly part of the nature park's Svete floodplain nature-barred area. During summer, the polder areas are flooded during high water levels of Lielupe. Still, during the summer, they must adjust the optimum humidity regime and ensure drainage systems, including drainage operation or to regulate the humidity regime in the floodplain, to preserve and restore the habitats of wetlands flood meadows and populations of native wild plants and animal species, also to ensure the use of agricultural land, reconstruction works have been carried out at the same time. The aim of this study is to assess the effects of rebuilding works on the hydrological regime of the Natura2000 site. In August 2021, 12 groundwater level monitoring points were established. At the monitoring point, 2 m deep pipes were installed in a 50 mm diameter, with a perforated lower part. Ejkelkamp Micro-Diver was inserted into the pipes, which records water levels every hour. Oneyear observation data were analyzed using descriptive statistics and Kruskal � Wallis. During the winter period, the polder flooded and drained systems for 65 days in the drained area and 156 days in the Natura2000 area.