Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län
Evaluations of open Ditch status and function, with an assessment of suitability of a conversion to a two stage ditch as a low maintenance alternative. To illustrate Swedish drainage problems this work focused on two agricultural drainage associations assessed in detail with a new method called M...
| Autor principal: | |
|---|---|
| Formato: | M3 |
| Lenguaje: | sueco Inglés |
| Publicado: |
SLU/Dept. of Soil and Environment
2013
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| Materias: |
| _version_ | 1855570909131177984 |
|---|---|
| author | Bornold, Pontus |
| author_browse | Bornold, Pontus |
| author_facet | Bornold, Pontus |
| author_sort | Bornold, Pontus |
| collection | Epsilon Archive for Student Projects |
| description | Evaluations of open Ditch status and function, with an assessment of suitability of a conversion to a two stage ditch as a low maintenance alternative.
To illustrate Swedish drainage problems this work focused on two agricultural drainage associations assessed in detail with a new method called MADRAS (Minnesota Agricultural Ditch Reach Assessment for Stability). With the assessment of the MADRAS method estimates were made to conclude the ditches operating
problems.
This was made through measurements of sediment depths, mass bank failures etc. in order to quantify ditch problems and propose practical actions for improved ditch stability and water quality.
The MADRAS surveys were conducted in two main ditches that drains 2900 hectares of land on the northern shores of Mälaren. In the study measurements of the ditch cross-sections were also conducted to compare actual profiles with the original map profiles.
The evaluation showed that parts of the studied ditch sections were operatively poor; main reason was mass bank failure, undercut channel banks, sediment aggregations
and narrowed ditches. The profile survey shows that a majority of the profiles 80 % has sediment accumulations there remains only 64 % of the original profile from the map. The survey also shows that 20 % of the profiles have been expanded by an average of 117 %. The study gives support to conduct further detailed investigations in the area and then accordingly determine an appropriate restoration plan.
The problems that ditch companies face today are to find means to deal with the higher flows. When this no longer can be overcome with the deepening of ditches, since additional drainage today severely restricted and new rulings from the water council is demanded for even smaller changes within ditch companies, alternative solutions must be proposed. Here proposed is to target especially exposed ditch stretches and reshape them into a two-stage ditch. There are many advantages with this design, but despite the fact that they do not lead to increased drainage they
currently fall under the same strict rules and needs court rulings to trial the impact assessment. To have drainage companies to implement two-stage ditch technologies
in their ditches a simplified permitting process for construction is necessary.
Imposition of these constructions is justified as they have wetlands characteristics of environmental benefits these are a greater immobilization of nitrogen and phosphorus
as well as decreased maintenance requirements.
The ditch evaluation method MADRAS is here considered to be a practical tool to be able to gather quantifiable measure of the ditch failing features. The evaluation provides a good foundation for finding the types of measures that should be applied to improve the function of the particularly vulnerable ditch stretches.
The evaluation showed that parts of the surveyed ditches were operationally poor, primarily because of mass bank failure, undercut channel banks and narrowed ditches. A viable solution in the worst affected ditch sections is to introduce a two-stage ditch. These measures would result in more stable channel banks but also even out peak channel flows that in the long run will improve water quality.
MADRAS method is made to measure and estimate the drainage systems operating problems and thereby determine if a maintenance or restoration plan may be developed in the area. The ditch evaluation method MADRAS is a suitable
method for ditch evaluation in Swedish conditions for identifying problem affected ditch stretches. |
| format | M3 |
| id | RepoSLU5820 |
| institution | Swedish University of Agricultural Sciences |
| language | swe Inglés |
| publishDate | 2013 |
| publishDateSort | 2013 |
| publisher | SLU/Dept. of Soil and Environment |
| publisherStr | SLU/Dept. of Soil and Environment |
| record_format | eprints |
| spelling | RepoSLU58202013-07-03T12:29:24Z Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län Evaluation of open ditch status and function : a pilot study in Västmanland Bornold, Pontus markavvattning markavvattningsföretag dikesutvärdering vattendragsmorfologi dikesunderhåll klimatanpassning Evaluations of open Ditch status and function, with an assessment of suitability of a conversion to a two stage ditch as a low maintenance alternative. To illustrate Swedish drainage problems this work focused on two agricultural drainage associations assessed in detail with a new method called MADRAS (Minnesota Agricultural Ditch Reach Assessment for Stability). With the assessment of the MADRAS method estimates were made to conclude the ditches operating problems. This was made through measurements of sediment depths, mass bank failures etc. in order to quantify ditch problems and propose practical actions for improved ditch stability and water quality. The MADRAS surveys were conducted in two main ditches that drains 2900 hectares of land on the northern shores of Mälaren. In the study measurements of the ditch cross-sections were also conducted to compare actual profiles with the original map profiles. The evaluation showed that parts of the studied ditch sections were operatively poor; main reason was mass bank failure, undercut channel banks, sediment aggregations and narrowed ditches. The profile survey shows that a majority of the profiles 80 % has sediment accumulations there remains only 64 % of the original profile from the map. The survey also shows that 20 % of the profiles have been expanded by an average of 117 %. The study gives support to conduct further detailed investigations in the area and then accordingly determine an appropriate restoration plan. The problems that ditch companies face today are to find means to deal with the higher flows. When this no longer can be overcome with the deepening of ditches, since additional drainage today severely restricted and new rulings from the water council is demanded for even smaller changes within ditch companies, alternative solutions must be proposed. Here proposed is to target especially exposed ditch stretches and reshape them into a two-stage ditch. There are many advantages with this design, but despite the fact that they do not lead to increased drainage they currently fall under the same strict rules and needs court rulings to trial the impact assessment. To have drainage companies to implement two-stage ditch technologies in their ditches a simplified permitting process for construction is necessary. Imposition of these constructions is justified as they have wetlands characteristics of environmental benefits these are a greater immobilization of nitrogen and phosphorus as well as decreased maintenance requirements. The ditch evaluation method MADRAS is here considered to be a practical tool to be able to gather quantifiable measure of the ditch failing features. The evaluation provides a good foundation for finding the types of measures that should be applied to improve the function of the particularly vulnerable ditch stretches. The evaluation showed that parts of the surveyed ditches were operationally poor, primarily because of mass bank failure, undercut channel banks and narrowed ditches. A viable solution in the worst affected ditch sections is to introduce a two-stage ditch. These measures would result in more stable channel banks but also even out peak channel flows that in the long run will improve water quality. MADRAS method is made to measure and estimate the drainage systems operating problems and thereby determine if a maintenance or restoration plan may be developed in the area. The ditch evaluation method MADRAS is a suitable method for ditch evaluation in Swedish conditions for identifying problem affected ditch stretches. För att belysa markavvattningsproblematiken har två dikningsföretag detaljstuderats inom ett avrinningsområde med nya undersökningsmetoder. Klimatet genomgår en förändring och detta påverkar diken med högre flöden som följd. I Sverige väntas en nederbördsökning på mellan 10-30 % och då markavvattningsföretagen är åldrade både i organisation och underhåll har detta skapat problem med avvattningen i svenskt jordbruk. Dikesutvärderingsmetoden MADRAS (Minnesota Agricultural Ditch Reach Assessment for Stability) utvärderas här som ett hjälpmedel att klassificera dikesstatus. I MADRAS metodens utvärdering klassificeras ett dike med grund i följande faktorer: sedimentmängd, släntras, dikesavsmalning och sammanställer dessa faktorer för att ge ett kvantifierbart mått på dikesstatusen. MADRAS undersökningar utfördes i två dikningsföretag i Munktorps socken, Västmanlands län dessa diken avvattnar tillsammans 2900 ha mark. I tillägg till MADRAS undersökning gjordes även mätningar av dikesprofilers tvärsnittsarea. Detta för att få uppskattningar av dikesstatus som är jämförbara med ett dikningsföretags originalritningar. Utvärderingen visade, att delar av de undersökta dikessträckorna var funktionsmässigt nedsatta. Främsta orsaken var kanalbankras, underskurna kanalbankar och avsmalnad dikesfåra. Undersökningen ger stöd för att inom området genomföra en detaljerad utredning och därefter fastställa en restaureringsplan. Profilundersökningen visar att en majoritet av profilerna 8 av 10 har sedimentansam-lingar där endast 64 % av ursprungsprofilen enligt plan. Samtidigt visar undersökningen även att 20 % av profilerna har förstorats med i genomsnitt 117 %. Ett problem som dikesföretagen står inför idag är hur de skall hantera de högre flödena, då detta inte går att avhjälpa med en fördjupning av diken eftersom ytterligare markavvattning idag kräver ny vattendom måste alternativa lösningar föreslås. Där ett förslag till kompromiss kan vara att istället speciellt utsatta dikessträckor omkonstrueras till ett tvåstegsdike. Fördelarna är många med dessa konstruktioner, men trots att de inte leder till ökad markavvattning krävs i dagsläget fortfarande en omprövning av miljötillståndet. För att lantbrukare skall kunna implementera tvåstegsdikesteknik inom respektive markavvattningsföretag, är en förenklad tillståndsprocess för anläggning nödvändig. Att även anläggningsstöd till dessa konstruktioner införs är motiverat då de likt våtmarker även äger miljöförbättrande egenskaper så som större fastläggning av kväve och fosfor samt minskat underhållsbehov. Dikesutvärderingsmetoden MADRAS anses här vara ett praktiskt användbart redskap för att kunna bestämma dikesstatus och därigenom fastställa ett kvantifierbart mått på dikesfunktion. Utvärderingen ger en god grund till vilka typer av åtgärder som bör kunna appliceras för att förbättra funktion i speciellt utsatta dikessträckor. Nyckelord: markavvattning, diken, dikesutvärdering, tvåstegsdike, terrassdike, trappstegsdike, fosforretention, kväveretention, kantzon, våtmarksalternativ. SLU/Dept. of Soil and Environment 2013 M3 swe eng https://stud.epsilon.slu.se/5820/ |
| spellingShingle | markavvattning markavvattningsföretag dikesutvärdering vattendragsmorfologi dikesunderhåll klimatanpassning Bornold, Pontus Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län |
| title | Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län |
| title_full | Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län |
| title_fullStr | Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län |
| title_full_unstemmed | Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län |
| title_short | Utvärdering av öppna dikens status och funktion : en förstudie i Västmanlands län |
| title_sort | utvärdering av öppna dikens status och funktion : en förstudie i västmanlands län |
| topic | markavvattning markavvattningsföretag dikesutvärdering vattendragsmorfologi dikesunderhåll klimatanpassning |