Joint use of multiple geophysical methods to map areas of organic matter in lakes

In this study three geophysical techniques; reflection seismic, ground penetrating radar and multiple electrode profiling, are measured at Lake Hampen. This groundwater seepage lake is located on sandy deposits and is one of the cleanest lakes in Denmark. The recorded reflections and the electrical property, along with cored data, are used to estimate the sediment types and thicknesses at the lake bottom. Areas with thick layers of gyttja or peat are expected to reduce groundwater seepage, while a sandy lake bottom will enable high rates of in- and outflow. The geophysical measurements thereby help identifying areas of potential groundwater seepage that later can be verified using more traditional point measurements.