EnviroInfo 2011: Innovations in Sharing Environmental Observations and Information Copyright 2011 Shaker Verlag Aachen, ISBN: 978-3-8440-0451-9 Analysing kettle holes in Mecklenburg in the last 225 years using an interdisciplinary virtual research laboratory Annelie Mai 1, Ralf Bill 1 Abstract Kettle holes are hollow forms smaller than 1 ha, of which some are filled with water. Until today, they are character- istical elements of the landscape of northern Europe, being originated glacially, quasi-natural or anthropogenic. Still, knowledge on the genesis and the embedding of these landscape elements is rather poor. Within the research project described here, our long term objective is to qualify the form of origin and development of each individual kettle hole. The research is done based on a virtual research environment for interdisciplinary research focusing on the landscape of the historical Mecklenburg (Bill/Walter, 2011). Georeferenced old maps from 1786, 1788 and 1877-1889 covering complete Mecklenburg are combined with current geo-information such as digital landscape/terrain models (DLM/DTM) and digital orthophotos (DOP) to support spatio-temporal research aspects in different scales in space (regional 1:200,000 to local 1:25,000) and time (nearly 225 years in three time steps). The Virtual Laboratory for Cultural Landscape Research (VKLandLab) is designed and developed by the Chair of Geodesy and Geoinformatics, hosted at the Computing Centre (ITMZ) and linked to the Digital Library (UB) at Ros- tock University. VKLandLab includes new developments such as wikis, blogs, data tagging, etc. and proven compo- nents already integrated in various data-related infrastructures such as InternetGIS, data repositories and authentica- tion structures. The focus is to build a data-related infrastructure and a work platform that supports students as well as professional researchers from different disciplines in their research in space and time. With respect to kettle holes the time series of maps are used to extract several parameters giving a hint of the genesis. Amongst others, this includes existence, the geometric shape, the location in the glacier landscape as well as in the terrain and the distance to the next brickyard. With the help of automated methods like automatic colour recognition more than 50,000 water filled kettles were identified in the topographic base maps from 1889, revealing that until today lots of elements have disappeared and others are added. In this project all kettle holes in the large investigation area (15,500 km²) are considered, while previous investiga- tions mostly focused on a few single objects. To facilitate successive researches, all gained attributes are saved in a VKLandLab database. 1. Introduction Kettle holes are hollow forms smaller than 1 ha, of which some are filled with water, but their genesis is different. For the kettle holes in Mecklenburg Klafs (1973) categorized three different types. The oldest form is the glacially originated kettle. Röpke (1929) developed the intramoraine ice-melting theory. Ac- cordingly kettles were formed during the last glacial period by glaciers, nearly 10,000 years ago. The se- cond type is the quasi-natural or pseudo kettle. It is filled by groundwater or surface water, often because of its position in the terrain, in depressions. The third type is the anthropogenic kettle. It has been created by humans for example in the process of mining sand, clay or marl. Kettle holes often are subjects of anthropogenic change and use. For the agriculture they mostly represent a barrier. Hence, farmers plough near kettles, so that they get smaller and smaller. In the past they often were used as kettle watering tanks, fowl ponds, fishing ponds or for washing and colouring. All these an- 1 Universität Rostock, Professur für Geodäsie und Geoinformatik, Justus-von-Liebig-Weg 6, D-18059 Rostock, email: {annelie.mai;ralf.bill}@uni-rostock.de, Internet: http://www.auf-gg.uni-rostock.de. thropogenic forces affected the water body and resulted in modifications of the shores. Today kettle holes in North-East Germany are saved by law (§ 20 I Nr. 1 NatSchAG M-V). For their flora and fauna as well as the aesthetics of the landscape they are worth to be protected. To get to know how a kettle hole is originated, sediment core drillings are a suitable possibility. Klafs (1973) described the layer structure of a glacial kettle as follows: mud, fen-peat, peaty mud and clayey mud on glacial till. In quasi-natural kettles the peaty mud and clayey mud are missing. However, for large investigation areas sediment core drillings are too expensive. Other methods have to be developed to allow conclusions of the genesis. Röpke (1929), Woldstedt (1955), Frielinghaus (1998) and Klafs (2000) found that glacial kettles typically exist in the ground moraine. Anthropogenic marl kettles are mainly located on the top in the terrain (Rixen 1805, Röpke 1929, Klafs 2000). These hypotheses have yet to be confirmed by a study using a large area under investigation. In the scope of this work we examined these and other proposals to deduce the genesis of kettle holes. While previous investigations mostly focused on a few single objects (6 in Riehl (2010), 22 in Florencio (2009), 144 in Kalettka (2006)) in a short observation period and small area, in this work a large area with much more kettles is focused. This investigation includes an area of nearly 15,500 km² in Mecklenburg (figure 1), nearly 50,000 kettle holes and an observation period of 225 years. Most of the area was formed in the last glacial period. The objective of this work is to get to know more about the spatial and temporal development of the kettle holes. Figure 1 Investigation area Mecklenburg with the area of the last glacial period according to Kalettka 2000 Copyright 2011 Shaker Verlag Aachen, ISBN: 978-3-8440-0451-9 2. Methods and materials 2.1 Data sources Georeferenced maps and current geo-information are the basis for this work. The old maps of Wiebek- ing (1786, 48 sheets, 1:24,000), Schmettau (1788, 16 sheets, 1:50,000) and the topographic base maps (1877-1889, 168 sheets, 1:25,000) were scanned and georeferenced. The maps from 1786 and 1788 were treated as one map. Thus only one time layer of kettle holes will be produced from them. For the current layer we used the already digitized water polygons of the DLM 2011 (digital landscape model) and the or- thophoto from 2007 (figure 2). Consequently, we got three time steps (1788, 1889, today). Figure 2 Section of maps near to Papendorf (Rostock) Schmettau (1788), topographic base map (1889) and Orthophoto (2007) The location accuracy of the examined objects is one of the main problems. For the map of Wiebeking the most points are in an area of inaccuracy of 40 m, for some it reaches up to values of 300 m. The old maps were evaluated in terms of their quality and their geometric origin by Kreßner (2009). He described possible quality aspects in his work, like measurement errors during the fieldwork, transmission errors and misprints in the cartographic implementation, warping of paper because of the storage or mistakes in digit- izing, georeferencing and vectorization. In this work these inaccuracies has to be taken into consideration. Additional base maps were the geological map of the federal state Mecklenburg-Vorpommern (Geo500, 1:500,000) from its geological service, department of the State Office for Environment and Nature Con- versation and Geology (LUNG) and the digital terrain model (DTM) from the Authoritative Topographic- Cartographic Information System (ATKIS). 2.2 Cultural Landscape Research - VKLandLab The processing of the kettle holes project is part of a bigger research project funded by the Deutsche Forschungsgemeinschaft (DFG) for investigation of the cultural landscape in Mecklenburg. Great im- portance is attached to a virtual research laboratory. All project participants work with a web environment, called Virtual Laboratory for Cultural Landscape Research (VKLandLab). This portal was designed and developed by the Chair of Geodesy and Geoinformatics. It is hosted at the Computing Centre and linked to the Library at the University of Rostock. VKLandLab includes new developments such as wikis, blogs, data tagging, etc. and proven components already integrated in various data-related infrastructures such as InternetGIS, data repositories and authentication structures. The focus is to build a data-related infrastruc- Copyright 2011 Shaker Verlag Aachen, ISBN: 978-3-8440-0451-9 ture and a work platform that supports students as well as professional researchers from different disci- plines in their research. The Internet-GIS kvwmap retrieves data for example from a local PostGIS spatial database system or via Web Feature Service (WFS) and Web Map Service (WMS). The virtual research platform is especially applicable for simultaneous editing. Different editors can work on the same layer at the same time. Kettle holes can be digitized simultaneously. Everybody imme- diately recognises changes, digitized and non-digitized areas. With the help of different colours the kettle holes can be marked, for example if they already have all possible attributes or not. So it is easy to see, which one has to be handled next. The attributes are saved in the tables of a database (figure 3). Figure 3 Data model for the kettle holes It is possible to export the different layers in shape-format. In this way the data can be used in different desktop-GIS tools for further analysis. Afterwards the results can be imported back into the virtual plat- form so that the database is up-to-date. The ESRI program ArcGIS was used for further analysis, because specialized analysis functions are not available in the Internet GIS kvwmap. Copyright 2011 Shaker Verlag Aachen, ISBN: 978-3-8440-0451-9 3.