Dagvatten i Märsta
Stormwater in urban areas has been treated as a problem for a long time. The large proportion of impermeable surfaces inhibits the water from infiltrating in the ground to the same extent that it does in nature. This causes intensive surface flow during rain, which in turn causes inconveniences...
| Autor principal: | |
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| Formato: | Otro |
| Lenguaje: | sueco sueco |
| Publicado: |
2008
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| Materias: | |
| Acceso en línea: | https://stud.epsilon.slu.se/12173/ |
| _version_ | 1855572013909803008 |
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| author | Wulff, Sofia |
| author_browse | Wulff, Sofia |
| author_facet | Wulff, Sofia |
| author_sort | Wulff, Sofia |
| collection | Epsilon Archive for Student Projects |
| description | Stormwater in urban areas has been treated as a problem for a long
time. The large proportion of impermeable surfaces inhibits the water
from infiltrating in the ground to the same extent that it does in nature.
This causes intensive surface flow during rain, which in turn causes
inconveniences such as decreased accessability, floods and increased risk
of desease spreading. Drainage through pipes is the traditional and usually
functional metod for storm water disposal. That is as long as water flows
are moderate. But precipitation varies naturally in amount and intensity
and additional impermeable surfaces make some pipes insufficient for
heavy or lasting precipitation. Poor infiltration will in the long run disturb
the balance in groundwater levels. In addition to this there is also a need
for alternative methods that handle the pollution, a need which has been
stressed more and more in the last decades.
Older sewer systems combine storm water with wastewater for treatment
in purification plants. That way pollution is taken care of; but intensive
waterflow decreases the puification effect and pipe overflows can occur in
lowland areas. Since the second half of the 20th century, all new stormwater
systems are separate from wastewater systems. Stormwater is disposed in
nature, which means a risk for species and ecosystems.
Today ponds, wetlands and permeable surfaces are often seen in urban
environment. These are examples of "ecological stormwater handling",
which has had a breakthrough connected to the strife for sustainable
development. The idea of ecological stormwater handling is to lead the
water back into its natural cycle and let natural processes take care of the
purifi cation. Using stormwater in the urban environment also gives other
benefi ts. This type of facilities are often designed as nice recreational
areas and at the same time the visual water cycle can have an educational
function. In some cases it is directly economically beneficial to replace the
traditional systems with ecological ones. It is important that the natural
systems used for stormwater handling are not at risk of being damaged.
Since the 1970's the leading term for alternative methods for stormwater
handling has been "local stormwater treatment". Together with the
development of techniques and the exchange of ideas, a multitude of
expressions have come to be used for description of similar phenomenons.
Here "ecological stormwater handling" is used as the main term since
it is understandable and quite well established. Within this term "local
stormwater treatment" has a more narrow definition.
The purpose of the proposal is to show an example of how the methods
presented can be taken into practical use. Märsta is a small but expanding
town in Sigtuna municipality just north of Stockholm. There are already
a number of stormwater treatment facilities and the opportunities of
craeating a coherent ecological stormwater system in the urban area. The
new facility is to be situated in Steningedalen nature reserve, which streches
from central Märsta toward lake Mälaren. The creek of Rosersbergsbäcken
has its natural outflow into the stream of Märstaån, which runs through
Steningedalen valley. But it is led into a culvert a little further upstream.
The idea is to restore the creek and lead it through sedimentation ponds and
to merge with Märstaån and at the same time improve the accessability to
the area for the inhabitants in Märsta. By linking toghether the new facility
with existing ones, a long continuous green strip is created through Märsta
and all the way down to lake Mälaren. It will also be a link in a blue-green
park strip through Märsta. |
| format | Otro |
| id | RepoSLU12173 |
| institution | Swedish University of Agricultural Sciences |
| language | Swedish swe |
| publishDate | 2008 |
| publishDateSort | 2008 |
| record_format | eprints |
| spelling | RepoSLU121732017-11-06T09:45:40Z https://stud.epsilon.slu.se/12173/ Dagvatten i Märsta Wulff, Sofia Water resources and management Stormwater in urban areas has been treated as a problem for a long time. The large proportion of impermeable surfaces inhibits the water from infiltrating in the ground to the same extent that it does in nature. This causes intensive surface flow during rain, which in turn causes inconveniences such as decreased accessability, floods and increased risk of desease spreading. Drainage through pipes is the traditional and usually functional metod for storm water disposal. That is as long as water flows are moderate. But precipitation varies naturally in amount and intensity and additional impermeable surfaces make some pipes insufficient for heavy or lasting precipitation. Poor infiltration will in the long run disturb the balance in groundwater levels. In addition to this there is also a need for alternative methods that handle the pollution, a need which has been stressed more and more in the last decades. Older sewer systems combine storm water with wastewater for treatment in purification plants. That way pollution is taken care of; but intensive waterflow decreases the puification effect and pipe overflows can occur in lowland areas. Since the second half of the 20th century, all new stormwater systems are separate from wastewater systems. Stormwater is disposed in nature, which means a risk for species and ecosystems. Today ponds, wetlands and permeable surfaces are often seen in urban environment. These are examples of "ecological stormwater handling", which has had a breakthrough connected to the strife for sustainable development. The idea of ecological stormwater handling is to lead the water back into its natural cycle and let natural processes take care of the purifi cation. Using stormwater in the urban environment also gives other benefi ts. This type of facilities are often designed as nice recreational areas and at the same time the visual water cycle can have an educational function. In some cases it is directly economically beneficial to replace the traditional systems with ecological ones. It is important that the natural systems used for stormwater handling are not at risk of being damaged. Since the 1970's the leading term for alternative methods for stormwater handling has been "local stormwater treatment". Together with the development of techniques and the exchange of ideas, a multitude of expressions have come to be used for description of similar phenomenons. Here "ecological stormwater handling" is used as the main term since it is understandable and quite well established. Within this term "local stormwater treatment" has a more narrow definition. The purpose of the proposal is to show an example of how the methods presented can be taken into practical use. Märsta is a small but expanding town in Sigtuna municipality just north of Stockholm. There are already a number of stormwater treatment facilities and the opportunities of craeating a coherent ecological stormwater system in the urban area. The new facility is to be situated in Steningedalen nature reserve, which streches from central Märsta toward lake Mälaren. The creek of Rosersbergsbäcken has its natural outflow into the stream of Märstaån, which runs through Steningedalen valley. But it is led into a culvert a little further upstream. The idea is to restore the creek and lead it through sedimentation ponds and to merge with Märstaån and at the same time improve the accessability to the area for the inhabitants in Märsta. By linking toghether the new facility with existing ones, a long continuous green strip is created through Märsta and all the way down to lake Mälaren. It will also be a link in a blue-green park strip through Märsta. Dagvatten i urbana miljöer har länge betraktats som ett problem. Den stora andelen hårdgjorda ytor gör att vattnet inte kan infiltrera i marken i den utsträckning som sker i naturen. Detta leder till kraftiga ytflöden vid regn, vilket i sin tur orsakar olägenheter som sämre framkomlighet, översvämningar och ökad smittrisk. Ledningssystem för avledning är den traditionella och oftast funktionella hanteringsmetoden. Så länge flödena inte blir alltför kraftiga. Men nederbörd varierar naturligt i mängd och intensitet och tillskott av hårdgjorda ytor gör att vissa ledningar inte räcker till vid häftig eller långvarig nederbörd. Dålig infiltration ger på sikt obalans i grundvattennivåerna. Dessutom krävs alternativa metoder för att hantera föroreningarna, ett behov som har betonats alltmer de senaste decennierna. I äldre ledningssystem förs dagvattnet tillsammans med avloppsvatten och till reningsverk. Det är ett sätt att bli av med föroreningarna men vid kraftiga flöden försämras reningseffekten och ledningarna kan svämma över i låglänta områden. Från och med andra halvan av 1900-talet anläggs bara separata system där dagvattnet leds ut i naturen, vilket innebär en risk för enskilda arter och för ekosystemen. Idag syns allt oftare dammar, våtmarker och genomsläppliga ytor i stadsmiljön. Dessa företeelser är exempel på ekologisk dagvattenhantering, ED, som fått stort genomslag i samband med strävan mot en hållbar samhällsutveckling. Idén med ED är att föra tillbaka vattnet till kretsloppet och låta det renas av naturliga processer. Att lyfta fram dagvattnet i utemiljön för även med sig andra fördelar. Ofta utformas denna typ av anläggning som vackra och trivsamma rekreationsmiljöer och samtidigt kan det synliga kretsloppet ha en pedagogisk funktion. I vissa fall är det direkt ekonomiskt fördelaktigt att ersätta de traditionella systemen med ekologiska. Viktigt är att de vattensystem som tar hand om dagvattnet inte riskerar att skadas. Sedan 1970-talet har lokalt omhändertagande av dagvatten, LOD, varit det ledande begreppet när det gäller alternativa metoder för dagvattenhantering. I takt med utvecklingen av tekniker och utbyte av idéer har en uppsjö kommit att användas för att beskriva samma eller liknande företeelser. ED används här som huvudbegrepp eftersom det är tydligt och någorlunda väl etablerat. LOD är aktuellt som en del av ED. Förslaget som presenteras syftar till att visa exempel på praktisk tillämpning av metoderna som studerats. Märsta är en liten men expanderande ort i Sigtuna kommun norr om Stockholm. Ett antal anläggningar för ekologisk dagvattenhantering finns redan samt goda möjligheter att skapa ett sammanhängande ekologiskt dagvattensystem i stadsmiljön. Anläggningen ska ligga i naturreservatet Steningedalen, som sträcker sig från centrala Märsta ner mot Mälaren. Rosersbergsbäcken har sin naturliga sträckning ut i Märstaån, som går genom dalen men är idag kulverterad en bit uppströms. Tanken är att restaurera bäcken och leda den genom sedimenteringsdammar ut i Märstaån och samtidigt förbättra områdets tillgänglighet för Märstaborna. Genom att länka samman den nya anläggningen med befintliga skapas ett långt sammanhängande grönstråk genom Märsta som sträcker sig ända ner till Mälaren. 2008-07-08 Other NonPeerReviewed application/pdf sv https://stud.epsilon.slu.se/12173/1/wulff_s_171106.pdf Wulff, Sofia, 2008. Dagvatten i Märsta : förslag till anläggning för ekologisk hantering samt metodöversikt. UNSPECIFIED, Uppsala. Uppsala: (NL, NJ) > Dept. of Urban and Rural Development (LTJ, LTV) > Dept. of Urban and Rural Development <https://stud.epsilon.slu.se/view/divisions/OID-595.html> urn:nbn:se:slu:epsilon-s-8595 swe |
| spellingShingle | Water resources and management Wulff, Sofia Dagvatten i Märsta |
| title | Dagvatten i Märsta |
| title_full | Dagvatten i Märsta |
| title_fullStr | Dagvatten i Märsta |
| title_full_unstemmed | Dagvatten i Märsta |
| title_short | Dagvatten i Märsta |
| title_sort | dagvatten i märsta |
| topic | Water resources and management |
| url | https://stud.epsilon.slu.se/12173/ https://stud.epsilon.slu.se/12173/ |