<p>The fully integrated 3-D, time dependant, hydrodynamic and sediment transport numerical model ECOMSED was used to simulate flow and sediment transport in rivers. ECOMSED was originally developed for large water bodies such as lakes and oceans and solves the primitive equations of RANS along with a second order turbulence model in an orthogonal curvilinear σ- coordinate system. The availability of the model as an open FORTRAN source code made modifications and addition of new models possible. A new bed load transport model was implemented in the code as well as improvements in treatment of river roughness parameterization, bed form effects, and automatic update of flow depth due to bed evolution. The model was applied to 1- km long reach of the River Klarälven, Sweden, where it bifurcates into two west and east channels. The water surface and the flow division in the channels were made in agreement with field data by spatially varying the roughness. However, the spatial distribution of the bed shear stress was not realistic. Improvements were made in the bottom boundary condition to represent the variable effects of bed forms on roughness depending on the flow regime and the flow depth. The improved model realistically reproduced the flow field as well as the sediment transport processes in the river Klarälven.</p>

The fully integrated 3-D, time dependant, hydrodynamic and sediment transport numerical model ECOMSED was used to simulate flow and sediment transport in rivers. ECOMSED was originally developed for large water bodies such as lakes and oceans and solves the primitive equations of RANS along with a second order turbulence model in an orthogonal curvilinear σ- coordinate system. The availability of the model as an open FORTRAN source code made modifications and addition of new models possible. A new bed load transport model was implemented in the code as well as improvements in treatment of river roughness parameterization, bed form effects, and automatic update of flow depth due to bed evolution. The model was applied to 1- km long reach of the River Klarälven, Sweden, where it bifurcates into two west and east channels. The water surface and the flow division in the channels were made in agreement with field data by spatially varying the roughness. However, the spatial distribution of the bed shear stress was not realistic. Improvements were made in the bottom boundary condition to represent the variable effects of bed forms on roughness depending on the flow regime and the flow depth. The improved model realistically reproduced the flow field as well as the sediment transport processes in the river Klarälven. / QC 20101123

Vid inträffandet av naturolyckor och katastrofer påverkas människor i olika omfattning, inte bara beroende på deras bostads läge utan även utifrån deras sociala förhållanden och förutsättningar. I denna studie genomförs en riskanalys samt utvecklas en metod för beräkning av ett områdes sociala sårbarhet genom ett index. Studiens geografiska avgränsning är en sträcka av Klarälven i Värmland och baseras på data framställt av Skogsstyrelsen, Myndigheten för samhällsskydd och beredskap (MSB), Lantmäteriet och Statistiska centralbyrån (SCB).   I studien beräknades ett socialt sårbarhetsindex genom att kombinera flera lager av SCB:s statistiska data i ett geodatalager med kvadratiska polygoner. Det sociala sårbarhetsindexet kombinerades sedan med resultatet från en flerfaroanalys (multi-hazard analysis) med flera översvämningsscenarion samt områden känsliga för jordskred och ras. Flerfaroanalysen utfördes genom en sammanställning av MSB:s kartering av potentiella översvämningsscenarion och Skogsstyrelsens kartering av områden som kan drabbas av ras eller jordskred. Det sociala sårbarhetsindexet och flerfaroanalysen karterades och överlagrades för att identifiera särskilt sårbara områden.   Med hjälp av det sociala sårbarhetsindexet identifieras en högre social sårbarhet i mer tätbebyggda områden. Indexet påvisar även en högre social sårbarhet i den södra halvan av studieområdet. I flerfaroanalysen ses naturolyckorna variera i omfattning över studieområdet. I den norra delen är risken för jordskred och ras större än i den södra delen som nästan enbart drabbas av översvämningar. Resultaten från riskanalysen visar en “medel-risk” längs en längre sträcka av Klarälven och ökad risk i tätbebyggda områden. För förbättring av det sociala sårbarhetsindexet behövs mer detaljerade data över mindre områden för att öka indexets tillförlitlighet och användningsområden. / When natural phenomena and disasters occur, people are affected to varying degrees, not only depending on the location of their homes, but also on the basis of their social background. In this study, a multi-hazard risk analysis and a method for estimating an area’s social vulnerability through an index were developed. The study was carried out along River Klarälven in Värmland and was based on data produced by the Swedish forest agency, The Swedish Civil Contingencies Agency (MSB), The Swedish Mapping, Cadastral and Land Registration Authority and Statistics Sweden (SCB).   The study presents a social vulnerability index by combining several layers of SCB's statistical data, in a geodata layer with square polygons. The social vulnerability index was combined with a multi-hazard analysis considering several flood scenarios and landslide susceptibility. The multi-hazard analysis was performed through a compilation of MSB's mapping of potential flood scenarios and the Swedish forest agency’s mapping of areas that may be affected by landslides. The social vulnerability index and the results from the multi-hazard analysis were mapped and combined in order to identify areas with substantial risk.    The social vulnerability index indicates a higher social vulnerability in more densely populated areas. The index also shows a slightly higher social vulnerability in the southern half of the study area. The results from the multi-hazard analysis, the spatial distribution of natural hazards varied. The northern part of the study area has a greater susceptibility to landslides than the southern part, which is almost exclusively are induced by floods and extreme flows. The result of the risk analysis shows a “medium risk” along the largest studied part of the River Klarälven and a slightly increased risk in densely populated areas. For future improvements in the development of the social vulnerability index, more data is needed with a higher spatial resolution to increase the index's reliability and areas of use.

Atlantic salmon (Salmo salar) are found in a range of locations along Sweden's coastline, but Sweden's largest lake, Vänern, also harbors a population of salmon; the rare freshwater migratory form. The majority of the salmon in Lake Vänern migrate upstream in River Klarälven in order to spawn, where they are assisted by humans through the "trap and transport" method to get past Klarälven's eight hydropower dams, which otherwise constitute definite obstacles to upstream migration. When the salmon later migrate downstream to Lake Vänern they receive no assistance and experience a high mortality rate as they are partially forced to swim through the turbines. The wild salmon population today includes over 1000 spawners annually, an increase from &lt;200 in the 196os, but far below historic records of over 10,000 spawners.  This report therefore aimed to investigate the population growth rate and extinction risk for the salmon in Klarälven, both in the current situation and with passages installed past the hydropower plants, and in doing so answer the questions 1) How large is the population growth rate and risk of extinction for today’s population of salmon in Klarälven over the course of 100 years? and 2) How would passage solutions past the hydropower plants in Klarälven affect the population growth rate and risk of extinction for today’s population of salmon in Klarälven over the course of 100 years? These questions were answered by running a population viability analysis in the program Extinction Vortex, which allows the programming of model populations and the manipulation of parameters to test different scenarios. The scenarios that were tested were 1) Scenario 1: Today's method with trap and transport and total lack of passages, 2) Scenario 2: Trap and transport continues, and downstream passages are installed past all eight power plants, and 3) Scenario 3: Upstream and downstream passages are installed past all eight power plants and trap and transport ceases. The results of the vulnerability analysis did not show any risk of extinction for the next 100 years, but a long-term negative trend for the salmon in Klarälven using today's method was seen. However, the development became significantly more positive for the salmon in Klarälven when the installation of downstream passages was simulated, but after that not significantly more positive when the installation of upstream passages was simulated as well. This result provided answers to the research questions and based on them it could be concluded that even though the salmon in Klarälven are not under any acute threat at the moment, and that there may be other fish populations in other regulated streams and rivers that would benefit more from environmental adaptation, measures need to be taken also in Klarälven, to ensure the long-term conservation of the unique freshwater migrating salmon that inhabit the area. / Laxen (Salmo salar) förekommer på flera håll längst Sveriges havskuster, men även Sveriges största insjö Vänern hyser en population av lax; den sällsynta sötvattensvandrande formen. Majoriteten av Vänerlaxarna migrerar upp för att leka i Klarälven, där de assisteras av människan genom metoden ”trap and transport” som tar dem förbi Klarälvens åtta vattenkraftverk vilka annars utgör definitiva vandringshinder. När laxen sedan ska ta sig tillbaka ner till Vänern får de ingen assistans, i stället tvingas de delvis simma genom turbinerna med stor dödlighet som följd. Laxpopulationen idag består av över 1000 lekande fiskar varje år, en ökning från &lt;200 individer på 1960-talet, men långt under historiska siffror på över 10 000 lekande laxar. Detta arbete syftade därför till att undersöka populationsutvecklingen och utdöenderisken för Klarälvslaxen, såväl i nuläget som vid en installation av passager förbi kraftverken, och genom detta besvara frågeställningarna 1) Hur stor är populationsutvecklingen och utdöenderisken för dagens population av Klarälvslax över kommande 100 år? och 2) Hur skulle passagelösningar förbi vattenkraftverken i Klarälven påverka populationsutvecklingen och utdöenderisken för dagens population av Klarälvslax över kommande 100 år? Dessa frågeställningar besvarades med hjälp av en sårbarhetsanalys i programmet Extinction Vortex, som tillåter uppbyggandet av modellpopulationer och manipulation av parametrar för att testa olika scenarier. Scenarierna som testades var 1) Scenario 1: Dagens metod med trap and transport och total avsaknad av passager, 2) Scenario 2: Trap and transport fortsätter samt nedströmspassager installeras förbi alla åtta kraftverk, och 3) Scenario 3: Upp- och nedströmspassager installeras förbi alla åtta kraftverk och trap and transport upphör. Resultatet av sårbarhetsanalysen visade inte på någon utdöenderisk kommande 100 år, men en negativ trend för Klarälvslaxens långsiktiga populationsutveckling med dagens metod. Utvecklingen blev dock signifikant mer positiv för Klarälvslaxen vid den simulerade installationen av nedströmspassager, och ännu något stabilare när även uppströmspassager installerades. Detta resultat gav svar på frågeställningarna, och utifrån detta kunde slutsatsen dras att trots att Klarälvslaxen inte befinner sig under något akut hot för närvarande, och att det kan finnas andra fiskpopulationer i andra vattendrag som är i mer akut behov av miljöanpassning, så behöver åtgärder komma på plats även i Klarälven, för att säkerställa det långsiktiga bevarandet av den unika sötvattensvandrande Klarälvslaxen.