REYKJAVÍK, ICELAND AUGUST 11-13, 2008 - Veðurstofa Íslands

This paper describes the stormwater management solutions that were
suggested by the Norwegian team. The Norwegian team prepared a report
with the title: Stormwater management at Urridaholt, Retail Park – Best
Management Practices. Final report 08 2005. Authors; Asle Aasen, Svein
Åstebøl, Sveinn Thorolfsson, Aasen et al. (2005)
The solutions are based on the goals for water quality in the lake and a
control of pollutants in the watershed, taking care of water and land
environment. By use of Sustainable Urban Drainage Systems (SUDS), the
goals for Lake Urriðavatn may be achieved.
THE STUDY AERA
Lake Urriðavatn is a small, shallow lake at 30 masl. The size of the
watershed is 235 hectares i.e. 2.350.000m2, where 460.000m2 are protected
area around Lake Urriðavatn, of which 200.000m 2 are wetlands.
Geography and urbanization
There are three hills in the watershed i.e. Urriðaholt in east, Setbergsholt in
west and Hádegisholt in south compared to Lake Urriðavatn. They arise up to
65 and 125 masl.
After the urbanization the area distribution between urban and not
urbanized areas in the watershed draining into Lake Urriðavatn from different
catchments, are shown in table 1.
Table 1. Future area distribution in catchments after the urbanization (area in
hectares, ha).
Catchment no. U-1 U-3 IB-27 IB-28 Sum %
Green areas in the
urbanized areas 8.5 18.0 8.9 6.5 41.9 46%
8.9 8.9 10%
Impervious areas in other
developing areas 22.0 10.9 7.9 49.4 44%
Sum urbanized areas 17.4 40 19.8 14.4 91.6 39%
Not urbanized areas 149.1 61%
The whole watershed 235 100%
Legend: U-1 is the IKEA lot, U-3 is Urridaholt and IB-27 plus IB-28 are Setbergsholt (holt = hill)
The firm, IKEA applied for a building permission for a shopping mall at
the lava peninsula north of Lake Urriðavatn. It initiated an evaluation of the
future runoff conditions and the potential pollution in the whole watershed to
Urriðavatn. The study resulted in the acceptance of the building permission
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