Flaten
| Flaten | |
|---|---|
 |
|
| Location | southern |
| Coordinates | 59°14′59″N 18°9′13″E / 59.24972°N 18.15361°ECoordinates: 59°14′59″N 18°9′13″E / 59.24972°N 18.15361°E |
| Primary inflows | Flatenån |
| Primary outflows | Drevviken |
| Catchment area | 403 ha (1,000 acres) |
| Basin countries | Sweden |
| Surface area | 63 ha (160 acres) |
| Average depth | 7.4 m (24 ft) |
| Max. depth | 13.6 m (45 ft) |
| Water volume | 4.56×106 m3 (3,700 acre⋅ft) |
| Residence time | 4 years |
| Shore length1 | 5,460 m (17,910 ft) (including island) |
| Surface elevation | 21.9 m (72 ft) |
| Islands | 1 (0.04 ha or 4,300 sq ft) |
| Settlements | |
| References | |
| 1 Shore length is not a well-defined measure. | |
Flaten is a lake in southern , Sweden, located just north of Lake Drevviken. The name is also used for the surrounding area and the nature reserve created there in 2007.
Flaten has the best water quality of all lakes around the Swedish capital and is highly popular for bathing and angling. The surrounding area is dominated by forests, with allotment-gardens and some industrial activities located north of the lake. Algal bloom occasionally occurs in spring.
The undulating wooded grounds of the catchment area are considered as of significant natural value and, through the location within a nature reserve and proximity to Stockholm, also of significant recreational value. A scenic ravine is found by the southern end of the lake while most nearby settlements are located north of it. The arrea is used for various open-air activities including walking, bathing, camping, canoeing, and fishing. The area is a fine example of the fissure-valley landscape prevalent in the entire , featuring elevated flat rocks separated by valleys with oaks and spruces, some of which can be several hundreds years old. In the catchment area are also three allotment-gardens and the residential area Skarpnäck. A bathe is located on the eastern shore. The catchment area for groundwater is much larger than that for stormwater.
In summer, when the lake is stratified, bottom layers suffer of oxygen depletion causing release of phosphorus. Treatment with aluminium chloride in 2000, however, greatly reduced the amount of leaking phosphorus. Most of the surface runoff reaching Flaten comes from a ditch (Flatendiket) stretching a kilometre to empty in the northern end of the lake where two sedimentation basins reduces the amount of pollutants reaching the lake. The ditch also receives stormwater from local settlements rich in nutrients and from the only road in the catchment area which contains metals and PAHs. Occasionally, the ditch therefore transports waste water to the lake which the available caissons mostly fails to treat properly. However, pipes from the bathe lead to a local sewage disposal plant, and, additionally, the catchment area was reduced by some 20 per cent in 1978 when stormwater from the graveyard Skogskyrkogården was guided past the lake, which decreased pollution but also increased lake retention time.
...
Wikipedia