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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Analys av sedimentackumulation i våtmarker i Rååns avrinningsområde och undersökning av våtmarkernas renoveringsbehov / Analysis of sediment accumulation in wetlands in the catchment area of Råån and an investigation of the maintenance needs of the wetlands

Lumsén, Louise January 2021 (has links)
Inom Rååns avrinningsområde, som är beläget i kommunerna Helsingborg, Landskrona, Svalöv och Bjuv, har anläggning av våtmarker pågått sedan 1990-talet. De anlagda våtmarkerna syftar till att minska näringsförlusterna från omkringliggande jordbruksmarker till vattendrag och gynna den biologiska mångfalden. I denna studie har 28 anlagda våtmarker inom Rååns avrinningsområde studerats. Studien hade två övergripande syften varav det ena var att undersöka sambandet mellan sedimentackumulering och våtmarkernas utformning samt placering i landskapet. Det andra syftet var att undersöka våtmarkernas renoveringsbehov. Renoveringsbehov syftar på åtgärder som behöver utföras för att upprätthålla våtmarkernas ursprungliga funktion och utformning såsom flödesvägar, vegetation, djupprofil samt in- och utlopp. Studien baserades på observationer och mätningar som utfördes i oktober år 2020. Resultatet visade att sedimentackumuleringen varierade mellan 0,2–2,3 cm per år och att både utformnings- och placeringsfaktorer påverkade sedimentackumuleringen. Det uppskattade ursprungliga vattendjupet hade en positiv korrelation med sedimentackumulationen och sedimentdjupet blev högre med våtmarkens ålder. Uppgrundningen var högre närmare inloppet i fyra av sju långsmala våtmarker (Längd-breddförhållande, 𝐿 ∶ 𝐵 > 3). I de långsmala våtmarkerna fanns även en positiv korrelation mellan hydraulisk belastning (HL) och sedimentackumulering. I våtmarker med 𝐿: 𝐵 < 3 fanns en övre gräns där höga värden på HL istället hade en negativ påverkan på sedimentackumuleringen. Våtmarkens storlek i relation till avrinningsområdet hade ett negativt samband med sedimentackumuleringen. Att många faktorer påverkade sedimentackumulationen gjorde att uppgrundningen skedde olika snabbt i våtmarkerna. Därmed kunde inte ett exakt åldersintervall för urgrävning fastställas. Däremot kan urgrävning potentiellt begränsas till början av våtmarker i de fall våtmarken är långsmal med djuphåla vid inloppet. De undersökta våtmarkerna hade varierande grad av renoveringsbehov. Urgrävning bedöms vara den mest resurskrävande åtgärden. Det är dock en nödvändig åtgärd om våtmarkerna ska fortsätta fungera som näringsfällor. Andra renoveringsbehov innefattade exempelvis enklare skötsel av vegetation, reparation av teknisk utrustning såsom rör och brunnar samt uppföljning av avtal med markägare för att se till att våtmarkerna förvaltas på sådant sätt att deras miljönytta gynnas. / Wetlands have been constructed within the catchment area of Råån since the 1990s. Råån is a river flowing through the municipalities Helsingborg, Landskrona, Svalöv, and Bjuv. The constructed wetlands aim to reduce nutrient leakage from surrounding agricultural land and increase biodiversity. In this study 28 constructed wetlands were studied with two aims: (i) to investigate the relationship between sediment accumulation in wetlands and wetland design and location in the landscape and (ii) investigate maintenance needs of the wetlands. Maintenance needs involve taking efforts to restore flow paths, depth profile, vegetation, and inlet and outlet to return the original function and design of the wetland. The study is based on observations and measurements carried out in October 2020. The results showed that sediment accumulation varied between 0.2–2.3 cm per year and that both wetland design and location affected sediment accumulation. Estimated original water depth had a positive correlation with sediment accumulation and sediment depth had a positive correlation with wetland age. The level of shoaling was higher closer to the inlet in four of seven long narrow wetlands (length- width ratio, L: W, > 3). In the long narrow wetlands, there was also a positive correlation between HL and sediment accumulation. However, in shorter and wider wetlands (L: W <3), there was an upper limit where high values of HL instead had a negative effect on sediment accumulation. Wetland area in relation to catchment area had a negative correlation with sediment accumulation. Shoaling rate is different in the wetlands since sediment accumulation is affected by many parameters. Thus, an exact time interval for excavation could not be determined. However, excavation can potentially be limited to the inlet of the wetlands if the wetland is long and narrow with a deep area near the inlet. The result showed that the wetlands had varying degrees of maintenance needs. Excavation is considered to be the most resource-intensive measure. However, excavation is necessary to maintain the function of the wetlands. Other maintenance needs include maintenance of vegetation, repair of technical equipment, and extension and enforcement of contracts with landowners to ensure that the wetlands are managed in such a way that the environmental function of the wetlands are favored.
2

Maintenance of the surviving spouse in South Africa : the challenges faced by the executor

Williams, Ronel Anneli 02 1900 (has links)
The Maintenance of Surviving Spouses Act 27 of 1990 came into operation thirty years ago and has remained relatively unchanged since its promulgation. The stated objective of the Act is to provide the surviving spouse with a claim for maintenance against the estate of the deceased spouse in certain circumstances. This objective is sound, as it is evident from an analysis of the history of our law that legislation was needed to address the financial position of a survivor following the death of his or her spouse. The practical application of the Act is, however, not as robust as it does not always achieve the stated objective and often leads to unintended consequences. This research has a dual objective. The first aim is to analyse the practical considerations when an executor applies the Act and to consider the challenges the executor must deal with when considering a maintenance claim under the Act. The second aim is to investigate possible solutions to these challenges and to consider whether there are viable alternative arrangements for the way in which a maintenance claim under the Act is handled. The purpose of the study is to formulate a comprehensive recommendation for legislative reform of the Act so that the practical application of the Act achieves a result that reflects the objective of the Act. / Private Law / LL.D.

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