Lake Constance (German: Bodensee, pronounced [ˈboːdn̩zeː] ) refers to three bodies of water on the Rhine at the northern foot of the Alps: Upper Lake Constance (Obersee), Lower Lake Constance (Untersee), and a connecting stretch of the Rhine, called the Seerhein (lit. 'Rhine of the lake(s)'). These waterbodies lie within the Lake Constance Basin (Bodenseebecken) in the Alpine Foreland through which the Rhine flows. The nearby Mindelsee is not considered part of Lake Constance.
The lake is situated where Germany, Switzerland, and Austria meet. Its shorelines lie in the German states of Baden-Württemberg and Bavaria; the Swiss cantons of St. Gallen, Thurgau, and Schaffhausen; and the Austrian state of Vorarlberg. The actual locations of the country borders within the lake are disputed, with Austria, Germany and Switzerland all holding different opinions on the matter.
The Alpine Rhine forms, in its original course (Alter Rhein), the Austro-Swiss border and flows into the lake from the south. The High Rhine flows westbound out of the lake and forms (with the exception of the Canton of Schaffhausen, Rafzerfeld and Basel-Stadt) the German-Swiss border as far as to the city of Basel. The Leiblach forms the Austria–Germany border east of the lake.
The most populous towns on the Upper Lake are Constance (German: Konstanz), Friedrichshafen, Bregenz, Lindau, Überlingen and Kreuzlingen. The largest town on the Lower Lake is Radolfzell. The largest islands are Reichenau in the Lower Lake, and Lindau and Mainau in the Upper Lake. Bodanrück, a large peninsula, separates the Upper and Lower Lake.
While in English and in the Romance languages, the lake is named after the city of Constance, the German name derives from the village of Bodman (municipality of Bodman-Ludwigshafen), in the northwesternmost corner of the lake.
Description
Lake Constance is located along the Rhine between the Alpine Rhine, its main tributary, and the High Rhine, its outflow. It is the third largest freshwater lake by surface area in Central and Western Europe (and the second largest in volume), after Lake Geneva and (in surface area) Lake Balaton.
It is 63 km (39 mi) long, and, nearly 14 km (8.7 mi) at its widest point. It covers about 536 km2 (207 sq mi), and is 395 m (1,296 ft) above sea level. Its greatest depth is 252 metres (827 ft), exactly in the middle of the Upper Lake. Its volume is about 48 km3 (12 cu mi).
The lake has two parts. The main east section, called Obersee or "Upper Lake", covers about 473 square kilometres (183 sq mi), including its northwestern arm, the Überlinger See (61 km2 (24 sq mi)); the smaller west section, called Untersee or "Lower Lake", covers an area of about 63 square kilometres (24 sq mi).
The connection between these two lakes is the Seerhein (lit.: "Rhine between the Lake(s)"). Geographically, usually it is not considered to be part of the lake, but a very short river.
The Lower Lake Constance is loosely divided into three sections around the Island of Reichenau. The two German parts, the Gnadensee (lit.: "calm lake") north of the island and north of the peninsula of Mettnau (the Markelfinger Winkel), and the Zeller See, south of Radolfzell and to the northwest of the Reichenau island, and the mainly Swiss Rheinsee (lit.: "Lake Rhine") – not to be mistaken for the Seerhein (lit.: "Rhine between the Lake(s)") at its start – to the south of the island and with its southwestern arm leading to its effluent in Stein am Rhein.
The water of the regulated Alpine Rhine flows into the lake in the southeast near Bregenz, Austria, then through the Upper Lake Constance hardly targeting the Überlinger See, into the Seerhein in the town of Konstanz, then through the Rheinsee virtually without feeding both German parts of the Lower Lake, and finally feeds the start of the High Rhine in Swiss town Stein am Rhein.
The lake itself is an important source of drinking water for southwestern Germany.
The culminating point of the lake's drainage basin is the Swiss peak Piz Russein of the Tödi massif of the Glarus Alps at 3,613 metres (11,854 ft) above sea level. It starts with the creek Aua da Russein (lit.: "Water of the Russein").
History
Lake Constance was formed by the Rhine Glacier during the Quaternary glaciation ice age and is a Zungenbecken or Tongue lake. After the end of the last glacial period, about 10,000 years ago, the Obersee and Untersee still formed a single lake. The downward erosion of the High Rhine caused the lake level to gradually sink and a sill, the Konstanzer Schwelle, to emerge.
The Rhine, the Bregenzer Ach, and the Dornbirner Ach carry sediments from the Alps to the lake, thus gradually decreasing the depth and reducing the extension of the lake in the southeast.
In antiquity, the two lakes had different names; later, for reasons which are unknown, they came to have the same name.
In the 19th century, there were five different local time zones around Lake Constance. Constance, belonging to the Grand Duchy of Baden, adhered to Karlsruhe time, Friedrichshafen used the time of the Duchy of Württemberg, in Lindau, the Bavarian Munich time was observed, and Bregenz used Prague time, while the Swiss shore used Berne time. One would have needed to travel only 46 kilometres (29 mi) to visit five time zones. Given the amount of trade and traffic over Lake Constance, this led to serious confusion. Public clocks in harbors used three different clock faces, depending on the destinations offered by the boat companies. In 1892, all German territories used CET, the Austrian railways had already introduced CET the previous year and Switzerland followed in 1894. Because traffic timetables had not been yet updated, CET became the sole valid time around and on Lake Constance in 1895.
Name
The earliest recorded reference to the lakes is by Roman geographer Pomponius Mela around AD 43, calling the upper lake Lacus Venetus and the lower lake Lacus Acronius, the Rhine passing through both. Around AD 75, the naturalist Pliny the Elder called them both Lacus Raetiae Brigantinus after the main Roman town on the lake, Brigantium (later Bregenz). This name is associated with the Celtic Brigantii who lived here, although it is not clear whether the place was named after the tribe or the inhabitants of the region were named after their main settlement. Ammianus Marcellinus later used the form Lacus Brigantiae.
The current German name of Bodensee derives from the place name Bodman, which probably originally derived from the Old High German bodamon which meant "on the soils", indicating a place on level terrain by the lake. This place, situated at the west end of Lake Überlingen (Überlinger See), had a more supraregional character for a certain period in the early Middle Ages as a Frankish imperial palace (Königspfalz), Alamannian ducal seat and mint, which is why the name may have been transferred to the lake ("lake, by which Bodman is situated" = Bodmansee). From 833 or 834, in Latin sources, the name appears in its Latinised form lacus potamicus. Therefore, the name actually derived from the Bodman Pfalz (Latinized as Potamum) was wrongly assumed by monastic scholars like Walahfrid Strabo to be derived from the Greek word potamos for "river" and meant "river lake". They may also have been influenced by the fact that the Rhine flowed through the lake.
Wolfram von Eschenbach describes it in Middle High German as the Bodemensee or Bodemsee which has finally evolved into the present German name, Bodensee. The name may be linked to that of the Bodanrück, the hill range between Lake Überlingen and the Lower Lake, and the history of the House of Bodman.
The German name of the lake, Bodensee, has been adopted by many other languages, for example: Dutch: Bodenmeer, Danish: Bodensøen, Norwegian: Bodensjøen, Swedish: Bodensjön, Finnish: Bodenjärvi, Russian: Боденское озеро, Polish: Jezioro Bodeńskie, Czech: Bodamské jezero, Slovak: Bodamské jazero, Hungarian: Bodeni-tó, Serbo-Croatian: Bodensko jezero, Albanian: Liqeni i Bodenit.
After the Council of Constance in the 15th century, the alternative name Lacus Constantinus was used in the (Roman Catholic) Romance language area. This name, which had been attested as early as 1187 in the form Lacus Constantiensis, came from the town of Konstanz at the outflow of the Rhine from the Obersee, whose original name, Constantia, was in turn derived from the Roman emperor, Constantius Chlorus (around 300 AD). Hence the French: Lac de Constance, Italian: Lago di Costanza, Portuguese: Lago de Constança, Spanish: Lago de Constanza, Romanian: Lacul Constanța, Greek: Λίμνη της Κωνσταντίας – Limni tis Konstantias. The Arabic, بحيرة كونستانس buħaira Konstans and the Turkish, Konstanz gölü, probably go back to the French form of the name. Even in Romance-influenced English the name "Lake Constance" gained a foothold and was then exported into other languages such as Hebrew: ימת קונסטנץ yamat Konstanz and Swahili: Ziwa la Konstanz. In many languages both forms exist in parallel e.g. Romansh: Lai da Constanza and Lai Bodan, Esperanto: Konstanca Lago and Bodenlago.
The poetic name, "Swabian Sea", was adopted by authors of the early modern era and the Enlightenment from ancient authors, possibly Tacitus. However, this assumption was based on an error (similar to that of the Teutoburg Forest and the Taunus): the Romans sometimes used the name Mare Suebicum for the Baltic Sea, not Lake Constance. In times when the Romans had located the so-called "Suebi", then an Elbe Germanic tribe near a sea, this was understandable. The authors of the Early Modern Period overlooked this and adopted the name for the largest lake in the middle of the former Duchy of Swabia, which also included parts of today's Switzerland. Today the name Swabian Sea (Schwäbisches Meer) is only used jocularly as a hyperbolic term for Lake Constance.
Key facts
No Paleolithic finds have been made in the immediate vicinity of the lake, because the region of Lake Constance was long covered by the Rhine Glacier. The discovery of stone tools (microliths) indicate that hunters and gatherers of the Mesolithic period (Middle Stone Age, 8,000–5,500 BC) frequented the area without settling, however. Only hunting camps have been confirmed. The earliest Neolithic farmers, who belonged to the Linear Pottery culture, also left no traces behind, because the Alpine foreland lay away from the routes along which they had spread during the 6th millennium BC. This changed only in the middle and late Neolithic when shore settlements were established, the so-called pile dwelling and wetland settlements, which have now been uncovered mainly on Lake Überlingen, the Constance Hopper and on the Obersee. At Unteruhldingen, a pile dwelling village has been reconstructed, and now forms an open air museum.
In 2015, a 20 km line of about 170 man-made under-water stone mounds dated in the Neolithic period or early Bronze Age was discovered on the south-west shore of the lake between Bottighofen and Romanshorn.
Grave finds from Singen am Hohentwiel to the north date to the beginning of the Early Bronze Age and shore settlements were repeatedly built during the Neolithic Period and the Bronze Age (up to 800 BC). During the following Iron Age the settlement history is interrupted. The settlement of the shore of Lake Constance during the Hallstatt period is attested by grave mounds, which today are usually found in forests where they have been protected from the destruction by agriculture. Since the late Hallstatt period, the peoples living on Lake Constance are referred to as the Celts. During the La Tène period from 450 BC, the population density decreases, as can be deduced partly due from the fact that no more grave mounds were built. For the first time, written reports on Lake Constance have survived. Thus, we learn that the Helvetians settled by the lake in the south, the Rhaetians in the area of the Alpine Rhine Valley and the Vindelici in the north-east. The most important places on the lake were Bregenz (Celtic Brigantion) and today's Constance.
In the course of the Roman Alpine campaign of 16/15 BC, the Lake Constance region was integrated into the Roman Empire. During the campaign, there was also supposed to have been a battle on Lake Constance. The geographer, Pomponius Mela, makes the first mention in 43 AD of Lake Constance as two lakes – the Lacus Venetus (Upper Lake) and the Lacus Acronius (Untersee) – with the Rhine flowing through both. Pliny the Elder referred to Lake Constance as Lacus Brigantinus for the first time. The most important Roman site was Bregenz, which soon became subject to Roman municipal law and later became the seat of the Prefect of the Lake Constance fleet. The Romans were also in Lindau, but settled only on the hills around Lindau as the lakeshore was swampy. Other Roman towns were Constantia (Constance) and Arbor Felix (Arbon).
After the borders of the Roman Empire were drawn back to the Rhine boundary in the 3rd century AD, the Alamanni gradually settled on the north shore of Lake Constance and, later, on the south bank as well. After the introduction of Christianity, the cultural significance of the region grew as a result of the founding of Reichenau Abbey and the Bishopric of Constance. Under the rule of the Hohenstaufens, Imperial Diets (Reichstage) were held by Lake Constance. In Constance, too, a treaty was drawn up between the Hohenstaufen emperor and the Lombard League. Lake Constance also played an important role as a trading post for goods being traded between German and Italian states.
During the Thirty Years' War, there were various conflicts over the control of the region during the Lake War (1632–1648).
After the War of the Second Coalition (1798–1802), which also affected the region and during which Austrian and French flotillas operated on Lake Constance, there was a reorganisation of state relationships.
Historical maps
1540: the map Lacus Constantiensis by Johannes Zwick and Thomas Blarer shows topographic names, towns and the Rhine.
1555: the map of the route of the Rhine (Rhinelaufkarte) by Caspar Vopel includes a topographical map of Lake Constance with its larger towns, the tributaries and the course of the Rhine.
1633: the Swabian map by Johannes Janssonius, Amsterdam: Totius Sveviae novissima tabula shows Lake Constance with islands, tributaries, towns and villages.
1675: The Lake Constance map, Lacos Acronianus sive Bodamicus, by Nikolaus David Hautt based on Andreas Arzet SJ shows Lake Constance with the adjacent lands.
Geography
Divisions
Lake Constance is located in the foothills of the Alps. The shore length of both main lakes is 273 kilometres (170 mi) long. Of this, 173 kilometres (107 mi) are located in Germany (Baden-Württemberg 155 kilometres or 96 miles, Bavaria 18 kilometres or 11 miles), 28 kilometres (17 mi) run through Austria and 72 kilometres (45 mi) through Switzerland. If the upper and lower lakes are combined, Lake Constance has a total area of 536 km2 (207 sq mi), the third largest lake in Central Europe by area after Lake Balaton (594 km2 or 229 sq mi) and Lake Geneva (580 km2 or 220 sq mi). It is also the second largest by water volume (48.5 km3 or 11.6 cu mi or 39,300,000 acre⋅ft) after Lake Geneva (89 km3 or 21 cu mi or 72,000,000 acre⋅ft) and extends for over 69.2 kilometres (43.0 mi) between Bregenz and Stein am Rhein. Its catchment area is around 11,500 km2 (4,400 sq mi), and reaching as far south as Lago di Lei in Italy.
The area of the Obersee, or Upper Lake, is 473 km2 (183 sq mi). It extends from Bregenz to Bodman-Ludwigshafen for over 63.3 kilometres (39.3 mi) and is 14 kilometres (8.7 mi) wide between Friedrichshafen and Romanshorn. At its deepest point between Fischbach and Uttwil, it is 251.14 metres (824.0 ft) deep.
The three small bays on the Vorarlberg shore have their own names: the Bay of Bregenz, off Hard and Fußach is the Bay of Fussach and west of that is the Wetterwinkel. Farther west, now in Switzerland, is the Bay of Rorschach. To the north, on the Bavarian side, is the Bay of Reutin. The railway embankment from the mainland to the island of Lindau and the motorway bridge over the lake border the so-called Little Lake (Kleiner See), which is located between the Lindau village of Aeschach and the island.
The northwestern, finger-shaped arm of the Obersee is called Überlinger See (or Überlingersee in Swiss Standard German), or Lake Überlingen. It is sometimes regarded as a separate lake, the boundary between Lake Überlingen and the rest of the Upper Lake runs approximately along the line between the southeast tip of Bodanrück (the Hörnle, which belongs to the town of Konstanz) and Meersburg. The Constance Hopper lies between the German and Swiss shores east of Konstanz.
The Obersee and Untersee are connected by the Seerhein.
The Untersee, or Lower Lake, which is separated from the Obersee and from its north-west arm, the Überlinger See, by the large peninsula of Bodanrück, has an area of 63 km2 (24 sq mi). It is strongly characterised and divided into different areas by end moraines, various glacial snouts and medial moraines. These various areas of the lake have their own names. North of Reichenau Island is the Gnadensee. West of the island of Reichenau, between the peninsula of Höri and the peninsula of Mettnau is the Zeller See (or Zellersee in Swiss Standard German), or Lake Zell. North of the peninsula and swamp land Mettnau lies the lake part Markelfinger Winkel. The drumlins of the southern Bodanrück continue along the bed of these northern parts of the lake. South of the Reichenau, from Gottlieben to Eschenz, stretches the Rheinsee (lit.: "Rhine Lake") with strong Rhine currents in places. Previously this lake part was named Lake Bernang after the village of Berlingen. On most of the maps the name of the Rheinsee is not shown, because this place is best suited for the name of the Untersee.
Emergence and future
The present-day shape of Lake Constance has resulted from the combination of several factors:
The tectonic Lake Constance Basin between the Alps and the Jura was created in the Jurassic and Tertiary periods.
The current Alpine Rhine was initially a tributary of the Danube.
Over time, the basin was captured by the High Rhine as a result of headward erosion (fluvial erosion).
The capture was not always only along the present Rhine valley; Lake Überlingen marks part of an older valley course.
The river valleys were deepened during several cold periods by the Rhine Glacier from the valley of the Alpine Rhine (glacial erosion).
Behind the present impressive traces of the Würm Ice Age, the effects of older cold periods can no longer be explored in any detail. Lake Constance now represents, above all, a zungenbecken or glacial lake of the Würm Glaciation.
During a later phase of the ice age, only the Obersee was glaciated. As the glacier retreated further, the glacial meltwaters flowed out of the emerging Überlingen See through the older more northerly valley into the present High Rhine valley.
Due to the advancing headward erosion, the present course of the High Rhine was finally (again) reconnected to Lake Constance.
Like any glacial lake, Lake Constance will also silt up by sedimentation. This process can best be observed at the mouths of the larger rivers, especially that of the Alpine Rhine. The silting up process is accelerated by ever-increasing erosion by the Rhine and the associated reduction in the level of the lake.
Tributaries
The main tributary of Lake Constance is the Alpine Rhine. The Alpine Rhine and the Seerhein do not mix greatly with the waters of the lake and flow through the lakes along courses that change relatively little. There are also numerous smaller tributaries (236 in all). The most important tributaries of the Obersee are (counterclockwise) the Dornbirner Ach, Bregenzer Ach, Leiblach, Argen, Schussen, Rotach, Brunnisach, Seefelder Aach, Stockacher Aach, Salmsacher Aach, the Aach near Arbon, Steinach, Goldach and the Old Rhine. The outflow of the Obersee is the Seerhein, which in turn is the main tributary of the Untersee. The most important tributary of the Untersee is the Radolfzeller Aach. The source of the Radolfzeller Aach is the Aachtopf, a karst spring whose waters mostly derive from the Danube Sinkhole. Therefore, the Danube is indirectly also a tributary of the Rhine.