Larger water bodies and geomorphology
Aarhus is located on the edges of large water bodies, with lakes to the west and Aarhus Bay and the Kattegat Sea to the east. It is also at the mouth of a west-east river valley, and the inner city is still centred on the banks of a central stream, connecting the hinterlands to the sea.
Aarhus belongs to a watershed that covers the coastal areas around the Aarhus Bay. The larger terrain properties of the area are shown on a Geomorphologic map by Per Smed: the Aarhus area is characterised by its tunnel valleys formed during the last glacial period (Weichsel Period) 11,700 years ago. Its moraine-clay hillsides define Aarhus to the north and the south, meeting on the low-lying grounds of the river valley.
Looking at the current 3D model of Aarhus, these landscape properties still read clearly. At a slightly larger scale, the area of contemporary Aarhus is defined by three river valleys: Giber Å, Ådalen and Egådalen.
The River Valley as an opportune location for settlement
The city´s relation to water is reflected in its name: Aarhus derives from Aros, meaning the mouth of the stream. This name was also used for other settlements in Denmark and Norway with similar waterscape relations. The river valley has hosted settlements for the last 9,000 years, and the existence of Aros can be traced back to the 800th Century when it was a Viking settlement (Terp Laursen, 2012, p. 20). The settlement was initially located in what is now the inner city around the cathedral.
At that time, the settlement was on a small island in what was formerly a fjord in the River Valley. Sedimentation, provided by water’s flow towards Aarhus Bay, the south-oriented hillsides, and easy access to water all provided rich fauna for hunting and arable lands for growing crops. In this way, Aarhus was located due to ´classic´ landscape based-parameters including access to water, food, transportation and protection.
Figur 3.1.12: The Town Arms of Aarhus, plate on railing above Aarhus Stream.
Figur 3.1.13: The geological map of soil types ´near the surface´
provides an overview at the scale of Denmark, telling hte story of the last glacial period, relating to the logics of the geomorphologic map (following page).
Source: GEUS.dk
Figur 3.1.14: A tracing of surface water and wetlands on the late 19th Century historical maps (HMB), emphasizing blue-green passages, wetlands, moist fields, canals, streams, and lakes.
Source: GST / blue tracing KW
Figur 3.1.15: Geomorphologic map, Eastern Jutland. Aarhus River Valley and its hinterland stretching 50 km westwards to the Jutlandic Ridge and the sandy heath plains. The overall directions of the terrain, show part of a landform with gradients and soils formed by waterscapes for almost 12.000 years . Ice and melting water have formed the tunnel valleys and moraine hills, a trait that has been further devel-oped in the interglacial period, where surface water continuously found its way in the corridors for thousands of years. This has created soil conditions where the smaller grain sediments have been washed out, creating capillaries leading water: soil conditions formed by waters movement. Source: Per Smed
Aarhus River Valley
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Figur 3.1.16: Top: Aarhus is located in water district 1.7, the catchment covers the larger Aarhus Bay area. Middle: Main catchment and groundwater.
Bottom: The main catchment Aarhus Bay with main tributaries and parish delineations.
Source: MiljøGIS
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Watershed and catchments in the larger Aarhus area
Figur 3.1.17: Top: Contemporary, larger landform of the larger Aarhus area. Bottom: as above, but with white lines indicating the catchment areas and blue showing surface water.
Source: QGIS
Visualisation: Nikolaj Knudsen
Draining and restoring wetlands in the river valley
In 1962, Hedeselskabet (The Danish Heath Society) initiated construction work to regulate the Aarhus Stream at the east and west ends of the lake, meaning that the area available to water was diminished by more than 25 per cent (Terp Laursen, 2012, p. 20). Nowadays, the river valley contains two larger lakes with wetland areas just in the hinterlands of the city; Brabrand Sø (Brabrand Lake) and Årslev Engsø (Årslev Lake), which was recently restored as wetlands and a lake.
The stream - from resource to nuisance
The older part of the city is located at a stream, formerly named Mølle Å (Mill Stream), and now known as Aarhus Stream (Aarhus Å). The central passage was the ford around what is now called Immervad5: the best location to cross the stream back in time. Just as in other expanding Western cities, the vital stream became a nuisance during the 19th Century. Aarhus Stream had become heavily polluted due to a growing number of industries and an increasing number of inhabitants.
The stream became the carrier of industrial wastewater from spinning mills, a glue factory, a tannery, a brewery and an abattoir alongside other sources of sewage in large amounts. Nevertheless, the stream was essential to the provision of drinking water, as well as for washing and bathing for less-privileged inhabitants. In the 19th Century, the stream was considered responsible for Staphylococcus outbreaks as well as Cholera and Typhus epidemics (Lundskov, 2016, p. 12; Terp Laursen, 2012, p. 15,20,30). Furthermore, the stream switched from being a primary infrastructure that connected the hinterlands to the sea, into being a barrier to contemporary urban practices. Newer modes of trans-portation, together with an expanding city and harbour, prioritised land-based, infrastructural connectivity between the north and south sides of the stream and towards the harbour. In this period, the stream changed from being considered as a natural resource into being viewed as a foul barrier for the city, as framed in a newspaper of 1909: ´Den stinkende, dybe muddergrøft6´ (Aarhus Stiftstidende, 24. Sept. 1909).
5പ The term ´vad´ means ford 6പ ͟The stinky, deep mud ditch͟
1865. Aarhus Stream from the West
1870. Aarhus Stream looking North-East, Slusebroen to Mølledammen (Mill Dam) 1890. Aarhus Stream from the Slusebroen (sluice bridge) towards East, city centre 1903. Aarhus Stream, Aagade (Stream Street)
1885, Aarhus stream at the sluice bridge, Aarhus Mølle (Mill) and Vesterbro Mølle
Figur 3.1.18: Source: Den Gamle By
Undergrounding and re-surfacing
Since the late 19th Century, different solutions for handling the stream were discussed, and, finally, during 1932-33 the stream was under-grounded and covered by dry infrastructure; Åboulevarden (the Stream Boulevard) (Lyngsø Pedersen, 2010; Ramböll, 1933; Terp Laursen, 2012, p. 20).
The undergrounding lasted until 1995-1996, when the stream was re-opened as a canal. The new area along the stream, now freed from cars, was mostly designated for leisure and business. Despite some initial resistance, the stretch became very popular, particularly for restau-rants, and its pedestrianisation has made it popular for strolling and as a ‘hang-out’ for young people. Today, the stream once again forms the inner spine of the city with new programmes, enclosed by hard edges and carefully designed pedestrian bridges, railings, and outdoor seating.
The stream has become an inner city icon of business and leisure –for visitors from outside Aarhus as well as locals.
In-between hinterlands and bay
From the point of view of water, the stream remains, of course, impor-tant to Aarhus beyond leisure, as it still functions as the outlet for the larger catchment of the river valley. In light of projections of increasing rain events and a rise in sea level, the stream becomes more important than its associated leisure programs: it is the mediating water body between the hinterlands and the sea. The spatial characteristics of steep, concrete retaining walls and rectilinear geometries do not, however, provide a flexible space for water. This puts pressure on the outlet and the areas where the river valley channels its water into the designed stream. A new lock has been constructed at the outlet to protect the inner city from storms and high tides by pushing seawater inwards. With more precipitation, the mouth of the stream and the larger river valley regain their importance for the settlement of Aarhus.
1878, Immervard seen from Ågade (The Ford seen from Stream Street.). The stream is recognised by steep edges and lines by trees. Except from the trees, the spatial characteristics at the present day stream are very similar to the late 19th Century
Appr.1980ies. Aaboulevarden on the buriede stream
Appr.1933. Aarhus Stream, inner city
Figur 3.1.19: Sources and copy-right: top: Lokalavisen. Middle:
Ingeniøren 1933. Bottom: Danske-billeder.dk
2016. Aarhus Stream, inner city
Figur 3.1.20: Top: Surface waterscapes as visible in the late 19th Century with outline of the Aarhus harbour 2014. Based on HMB, GST (mapping and graphic:
KW). Bottom:The larger Aarhus area shown with greyscales indicating the dregrees of surface cover
Source: MiljøGIS / greytones: KW
Figur 3.1.21: Aarhus Stream was formerly the vein of the city - today it has importance in a different manner; recreation, leisure, shopping and identity.
From upper left to lower right (from the West towards East and the Aaarhus Bay)
i: Soft edges, lower brinks in the restored wetland h+g: Soft edges, lower brinks at the Allotment Gardens in Brabrand
f: New residential blocks, soft edges e: Public recreation by the canal, inner city d+c: Steep retaining wall with design attention, shopping and leisure area of the inner city b: the new lock at Dokk1, protecting the inner city from the sea
a: Inner harbour.
Photo (i): Niels Nygaard
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