Climate Change and Transboundary Water Management in the Tunisian Mellegue Catchment / Klimatförändring och gränsöverskridande vattenhantering i Mellegue avrinningsområde, Tunisien
Human activities and climate change affect hydrological and sedimentological characteristics within catchments. For arid and semiarid areas this induces direct negative economic and environmental consequences on society. In fact, stability in the rainfall regime and less siltation trapped in reservoirs mean more water for irrigation, water supply, and better flood control. This is especially important in the Tunisian semiarid region where water needs are close to potential water resources and siltation is reducing the reservoir capacity rapidly. Wadi Mellegue was chosen in order to study trends of water resources availability. Linear regression modelling and Mann-Kendall tests were performed for trend analysis. The study dealt with rainfall, discharge, and sediment patterns in the catchment area during a 44-year period. The results display a common decline in rainfall depth at different time scales. However, a positive trend related to discharge and siltation process was found. An increase in vulnerability to the new climate conditions is described. Consequently, water resources and agricultural landscape management for the Mellegue catchment should be revised in order to ensure a sustainable up- and downstream catchment development.
This study aims to preliminarily evaluate changes in the risk of cyanobacterial blooms in a eutrophic lake, Lake Vombsjön, in the southern Sweden and test the role of nutrients (phosphorus and nitrogen) in algae formation. Surface water such as lakes service great importance for drinking water supply, such as half of the drinking water in Sweden is from surface water. According to risk matrix, Lake Vombsjön is of high risk of blooms and special attention should be paid in late summer and autumn as the later the blooms occur, the more likely they are cyanobacteria induced. Results confirmed phosphorus control to be the key for controlling cyanobacterial blooms in eutrophic lakes such as Lake Vombsjön as well as keeping N/P ratio (Nitrogen/phosphorus) at certain high level. The most frequent types of cyanobacteria in Lake Vombsjön are Planktothrix agardhii. Pseudanabaena should be monitored. Future work should consider long term pattern analysis, including the hydrodynamic condition in the lake. This work will support harmful algea blooms management in practice.
Wastewater treatment plants as energy-producers: Comparison of the status in India and Sweden / Avloppsreningsverk som energiproducenter: Jämförelse av status i Indien och Sverige
As the population of the world rises and economies grow, both energy and water will be needed in ever-increasing quantities. There is a delicate balance between these two resources called the energy-water (or the water-energy) nexus. One way to reduce the energy consumption associated with wastewater treatment is to use the sludge produced during the process to generate biogas. In most countries in the developed world, the coverage, standards and reliability of wastewater treatment are high. But as the countries in the developing world are striving towards the living standards of those in the developed world, even as they combat population pressure, it is imperative that they learn from the experiences (the mistakes which occurred during the ‘learning-by-doing’ process) of the developed world. In this paper, Sweden has been used as a proxy for the developed world with a well-functioning sanitation infrastructure and reliable power supply; and India (the home country of one of the coauthors) is a proxy for the developing world which lacks the same. A very important starting point for development would be to educate people about the long-term socio-economic and environmental benefits of wastewater treatment.
En flödesanalys för Kävlingeån – HEC-RAS modellering med fokus på dämmens inverkan / An analysis of the Kävlinge River flow situation – HEC-RAS modeling with focus on the effects of weirs
Kävlinge River is one of the largest, and most heavily fish-populated, watercourses in Scania. Eight dams and three active hydroelectric plants are located here, which cause environmental problems; organisms are prevented migration, reproduction and feeding being the biggest issues. Trout and eel, which depend on river accessibility and spawning areas, inhabits the river. This study aims to create a hydraulic model over Kävlinge River, with the purpose of analyzing flow simulations for the effects of proposed dam removals. A shorter model was created from sonar-based data sources, as well as a longer model in which bathymetry was estimated from different data sources. Simulations showed that at least 83 % of the area between Högsmölla and Håstad mölla is dammed, and that the river have potential for recreating areas with higher water velocities; mainly by lowering the dam at Högsmölla. The shorter model showed possible creation of 400–6500 square meters increase in stretches combining the dams at Högsmölla, Silverforsen and Rinnebäck with fauna passages and partial dam removal. The corresponding result for the longer model was 1200–17000 square meters including the dams at Lilla Harrie, Bösmöllan and Kvarnvik. This result, however, has a greater uncertainty.