CANAPE welcomes students to work at Holter Meer
Lake Holter Meer, also known as Großes Meer, is the German CANAPE field trial site for lake restoration. It is located in Diepholz County in Lower-Saxony and has a water surface of 11.2 ha with a surface catchment area of 47.3 ha. Since 1942 this lake has been a protected landscape. Nowadays, it suffers by heavy eutrophication due to surrounding agriculture, accelerated sedimentation, longterm reduction of water level and loss of biodiversity.
The main focus of CANAPE activity in this site is the preparation and application of the PCLake methodology to improve preexisting restoration planning, and consultancy with farmers and stakeholders for nutritional management and extensification of agriculture.
In this context, German CANAPE partnership has welcomed Lina Otte and Frederike Müller, both students of Environmental Science in their 6th semester from the Carl von Ossietzky-University of Oldenburg, to carry out research at the site. The early state research will investigate the role of the groundwater under and around the Holter Meer in order to gather information on the causes of the eutrophication that affect the local flora and fauna. The objective of the research is to find a way to sustainably renovate the lake and make it attractive for residents and visitor again. Prof. Dr. Gudrun Massmann and PhD student Tobias Holt from the research team “Hydrology and Landscape Water Balance” at the CvO-University are supervising the work.Their bachelor thesis work will strongly support the collection of data necessary for PCLake modelling. The modelling will be conducted by the Dutch partner Van Hall Larenstein University of Applied Sciences.
In order to estimate the impact of groundwater on the lake’s eutrophication the hydraulic connection of the groundwater to the lake and also the nutrient concentrations at several measuring points will be examined. To achieve this groundwater measuring stations have been built with a depth of 1-2 meters around the lake. In addition some already existing measuring stations in the vicinity will be used to conduct part of the research. To establish an overview of the nutrient distribution on-site parameters such as oxygen concentration, temperature, conductivity, pH value and the ammonium content will be examined, and phosphate and the main anions and cations will be measured in the lab. Various methods on land and on water will help to quantify the emerging groundwater during early summer 2018 and to locate the points of influx. In addition, based on long-term water budget calculations, an attempt shall be made to identify year-round sources of the lake’s water and calculate the approximate water retention time in the lake.
Below - Use of an infra-red camera to detect cold groundwater entering the lake.