Eawag, Überlandstr. 133, CH-8600 Dübendorf, Switzerland
River Thur (1730 km2), NE Switzerland, and RECORD research site at Neunforn (http://www.cces.ethz.ch/projects/nature/Record)
The River Thur is located in NE Switzerland, draining the front ranges of the Swiss NE Limestone Alps (S of the Bodensee basin). It is a tributary of the R. Rhine which flows into the North Sea. The map below shows the Thur catchment with Mt. Säntis (2502 m).
The Thur catchment is a mainly Limestone dominated alpine headwater, whereas the pre-alpine lowlands are dominated by ‘Molasse’-Sandstones and Pleistocene unconsolidated sediments. It is a primarily rural catchment with agricultural activity focussing on the lowlands and scattered settlements. St. Gallen (72,000 inhabitants) and Frauenfeld (23,000 inhabitants) are the largest towns in the Thur catchment.
The primary aquifer (Thur valley aquifer) is mainly sand and gravel. It is connected to the Thur river and mostly unconfined. The depth to the water table varies very much in the entire catchment. This information can be given upon request. The water table at the RECORD field site Neunforn is mainly shallow (see information below). Supporting data are also available, for example geological or hydrogeological maps. The Thur valley aquifer is shown below.
The R. Thur is the largest Swiss river without a natural or artificial reservoir and exhibits fluctuations in discharge and water table similar to unregulated alpine rivers (low discharge: 3 m3s-1; annual mean discharge: 23.3 - 76.4 m3s-1; peak flows up to 1100 m3s-1). Snowmelt and strong rainfall events in the pre-alpine headwaters cause short but rapid increase of discharge. During base flow outflows of sewage treatment plants are significant contributions. Due to flood protection in the 1980s, the river was straightened and confined to a narrow channel surrounded by 50 – 150 m wide overbanks defined by a levee, behind which a side channel was installed to capture discharge from tributaries and drain agricultural land. In recent years river restoration measures were established with the aim to improve flood protection and the ecological status of the river and the riparian zone.
The activities focus on the R. Thur, the largest river in Switzerland without a natural or artificial reservoir. The revitalization of the R. Thur is one of the largest ongoing projects in Switzerland. The monitoring objective is to improve the mechanistic understanding of coupled hydrological and ecological processes in near-river corridors. For this purpose, the following was accomplished :
Record field site near Neunforn. A: observation towers; B: piezometers/wells (approx. 80); C: groundwater measurements; D: meteorological measurements (3 stations); E: ecological monitoring and soil measurements.
The main field site is the restored Thur section at Neunforn (Canton Thurgau) and Altikon (Canton Zurich). The main foci are to:
Several administrative and research organisations actively support monitoring and evaluation of data within the Thur catchment. The Office for the Environment (Amt für Umwelt) Thurgau and the Office for Water, Waste and Energy (Amt für Wasser, Abfall und Energie) Zurich are monitoring the Thur catchment. The records go back until the 1870s. Both organisations established close collaborations with Eawag and the ETH Zurich. All demonstrate a strong commitment to the observatory. In addition, data are available online through the Swiss Federal Office of the Environment (FOEN) and the Swiss governmental monitoring network (Meteoschweiz). The Niederneunforn, Widen and Rietholzbach sites are also part of Eawag’s commitment to climate change and pre-alpine catchment research.
Rainfall data are measured at 41 stations in the Thur catchment by Meteoschweiz (governmental monitoring network), plus additional research stations at specific sites, some of them providing online access. Several climate stations in the Thur valley are operated by the canton Thurgau, where data are available, plus additional weather stations at the RECORD and Rietholzbach sites.
Flow data are measured at the catchment outlet and at a network of additional stations by the FOEN. Monthly and daily flow and information on flow peaks are available online; higher resolution data (15 min) is available upon request. These sites and the period of record are shown below. Data can be downloaded from:
Research activity and outputs