Chloride transport in a small catchment of the Norrström basin.
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
On a catchment scale, chloride (Cl-) leached from forest soil due to dry deposition and interaction between vegetation and soil could attribute to the Cl- mass balance. The availability of Cl- data from monitoring works enables the assessment of net ecosystem budgets of Cl-, which compares Cl- amount from wet deposition to that in stream export. Some studies have shown that Cl- imbalances could occur in some catchments and one of such catchments with negative budget is Kringlan. The Kringlan catchment is a sub-basin located on the western boundary of Norrström basin and for this project, a southern sub-catchment with a size of 54.5 km2 within Kringlan catchment was chosen to be studied. To fulfill the Cl- budget, one possible internal source of Cl- leached from forest soil was added and tested. Moreover, a field trip to the study site was performed and soil samples were taken back for leaching test analysis. The evaluation of Cl- transport through the catchment requires the water flow and MIKE SHE was selected as the tool for flow simulation in an integrated manner. Lastly, the Particle Tracking (PT) module helped to analyze the Cl- transport through saturated zone in a time span of 100 years for a simplified scenario. Results show that the calibrated chloride concentration to groundwater leached from forest soil (-1 m to -5 m below the ground) was 200 mg/l. A total chloride leaching amount from forest subsurface was calculated as 4287 tons during calibration stage of 5 years. However, only 265 tons of chloride for 5 years could be transported out from the catchment for the calibration period, which corresponds to a leaching flux rate of 1.3g/m2/yr. It was found that the flow discharge rather than the Cl- concentration dominated the Cl- transport loads at the outlet, both in variation and magnitude. For future studies, some other possible internal sources, e.g., mineral weathering, road salting and etc. need to be researched.
Place, publisher, year, edition, pages
, TRITA-LWR Degree Project, ISSN 1651-064X ; 2014:08
Chloride; Catchment; Net Budget; Internal source; Leaching; Modeling
IdentifiersURN: urn:nbn:se:kth:diva-171778OAI: oai:DiVA.org:kth-171778DiVA: diva2:844482
Degree of Master - Environmental Engineering and Sustainable Infrastructure
Cvetkovic, Vladimir, professor