ABSTRACT: The surface and groundwater monitoring network in the Danube floodplain was set up as a part of the project LIFE 14 NAT/SK/001306. Thanks to the high flow in the old river bed of the Danube River the surface and groundwater interaction could be studied by measuring water levels and water temperatures. Peak of the high flow in the river was ten times higher that the average one and the high flow lasted eight days. The water levels were measured and then analysed by help of profiles, perpendicular to the river. Temperatures were approximated by sinusoid and analysed by help of charts. The results show that the change in the groundwater level was nearly 4 meters by the river and reach more than 1,500 meters from the river, where the change was 1.5 meter. The biggest change in the groundwater temperature was 1 °C, 30 meters from the river and reach more than 430 meter to the contrary to other studies, where authors declare maximal reach up to 200 meters.