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Due to precipitation poor winters and springs and over-exploitation of groundwater reserves during the summer months as a consequence of tourism, the island of Gotland has experienced fresh water shortages during recent years which has led to harsh restrictions in the use of municipal water. In order to find a solution to the islands fresh water problems, the region of Gotland and the Swedish Environmental Institute (IVL) have initiated a project in which the southernmost part of Gotland, Storsudret, will be used as a test site for new methods of sustainable freshwater storage and extraction methods. A, for Sweden, new method currently being investigated is the use of subsurface dams in order to increase the storage capacity of soil groundwater, thus increasing the possible extractions. Methods for finding suitable sites for subsurface dams has been investigated by Imran Jamali, 2016, and Ludvig Almqvist, 2017. There is however a need in further investigating and developing methods for subsurface dam location. This master thesis has focused on performing on-site data collection and on the use of groundwater flow model to evaluate the possibility of placing a subsurface dam on Storsudret, as steps in a method to localize areas suitable for subsurface dams. On site data was collected through resistivity measurements and water level measurements. This was used as input data for the flow model, MIKE SHE, together with more general GIS-data available. Flow modelling was performed during the period 2015-2018, which included the initially dry years of 2015-16 and the summer of 2017, and the more precipitation rich second half of 2017 and spring of 2018. Subsurface dams were modelled to investigate the results on the surroundings. The result did not show any obvious locations for the placement of a subsurface dam within the modelled area. The site considered to be most suitable for dam placement was modelled but showed only a rather small additional stored volume. However, the model result indicated that large possibilities for freshwater extraction already could be present in an existing geological formation in the area, even without the presence of a subsurface dam. As a tool for finding the specific location of groundwater dams, it was concluded that MIKE SHE gives a good overview over the general hydrogeological features and flow paths. Thus, it is a valuable tool when it comes to finding interesting sites for further investigations. However, due to problems in obtaining detailed enough input data, the model is considered to be less suitable for finding specific locations for dam placement when investigating a larger domain. / På grund av nederbördsfattiga vintrar och ett överuttag från grundvattenreservoarerna under turistsäsongen på somrarna, har Gotland erfarit vattenbrist under senare år vilket lett till hårda bevattningsförbud för såväl kommunalt och enskilt vatten. För att hitta en lösning på denna vattenbrist har Region Gotland och Svenska Miljöinstitutet (IVL) initierat ett projekt på den södra delen av Gotland, Storsudret, som kommer att användas som en testplats för nya lösningar inom lagring och uttag av färskvatten. En, för Sverige, ny metod som för nuvarande undersöks är användandet av grundvattendammar som ett sätt att öka lagringskapaciteten i marken och på så sätt kunna öka uttagen av grundvatten. Metoder för att finna lämpliga platser för grundvattendammar har undersökts av Imran Jamali, 2016, och Ludvig Almqvist, 2017. Därtill finns ett behov av att vidare undersöka och utveckla metoder för lokalisering av grundvattendammar. Denna masteruppsats har fokuserat på att utföra data-inhämtning i fält och bygga upp en grundvattenflödesmodell för att utvärdera möjligheten att placera en grundvattendam på Storsudret, som ett vidare steg i att utveckla en metod för att finna lämpliga platser för grundvattendammar. Data från fältundersökningar hämtades genom resistivitetsmätningar och vattenståndsmätningar. Dessa data användes som inmatning i grundvattenflödesmodellen, MIKE SHE, tillsammans med mer generell GIS-data. Flödesmodellering utfördes under perioden 2015-2018, vilket inkluderade torrår under perioden 2015-2016 och slutet av sommaren 2017 och mer nederbördsrik period under hösten 2017 och våren 2018. Grundvattendammar modellerades för att undersöka områdespåverkan. Resultaten visade på ingen självklar lokalisering för en grundvattendamm inom det modellerade området, på grund av platt geologi utan tydliga utflödespunkter blev resultatet av en damm endast en liten ökad grundvattenvolym. Däremot visade modellresultaten att stora uttagsmöjligheter för grundvatten redan fanns i existerande geologiska formationer även utan en grundvattendamm närvarande. Som ett steg i metoden att finna lämpliga platser för grundvattendammar var MIKE SHE ett bra verktyg för att ge en god överblick över de generella hydrogeologiska flödena. MIKE SHE är ett värdefullt verktyg när det kommer till att hitta intressanta platser för vidare undersökningar. Däremot fanns problem med att finna detaljerade inmatningsdata vilket gör modellen mindre lämplig för att finna exakta grundvattendamsplaceringar inom ett större område.

This thesis presents a method, Ensemble Kalman Filter (EnKF), applied to a highresolution, shallow water equations model (DG ADCIRC-2DDI) of the Lower St. Johns River with observation data at four gauging stations. EnKF, a sequential data assimilation method for non-linear problems, is developed for tidal flow simulation for estimation of state variables, i.e., water levels and depth-integrated currents for overland unstructured finite element meshes. The shallow water equations model is combined with observation data, which provides the basis of the EnKF applications. In this thesis, EnKF is incorporated into DG ADCIRC-2DDI code to estimate the state variables. Upon its development, DG ADCIRC-2DDI with EnKF is first validated by implementing to a low-resolution, shallow water equations model of a quarter annular harbor with synthetic observation data at six gauging stations. Second, DG ADCIRC-2DDI with EnKF is implemented to a high-resolution, shallow water equations model of the Lower St. Johns River with real observation data at four gauging stations. Third, four different experiments are performed by applying DG ADCIRC-2DDI with EnKF to the Lower St. Johns River.

Using an instrumented water quality network in Morro Bay Estuary, California from 2007 to 2010 (15 min sampling frequency), this study addressed the two objectives of constructing a nitrate budget and assessing the influence of sampling frequency on water quality parameters. These two objectives led to the submission of an original report of research (Appendix A) and a note (Appendix B) to peer-reviewed journals. The first objective was to characterize the high spatial and temporal variation in physical parameters and nitrate concentrations and to construct a nitrate budget quantifying sources and sinks of nitrate from the ocean, streams, and groundwater, as well as biological processes in the Estuary. Morro Bay Estuary was found to be a non-eutrophic system and a mean net exporter of nitrate, 327.15 t yr-1. Fifty-four percent of the nitrate export was attributed to nitrate sources and internal biological processing. Nitrate loading from streams contributed 37 % to the export of nitrate (124.01 t yr-1), while groundwater nitrate loading supplied a conservative estimate of 46 % of the exported nitrate (153.92 t yr-1), with a neap tide enhancement of the discharge. Denitrification, Zostera marina, and benthic macroalgae assimilation of nitrate were the dominant internal biological processes for removal and retention, but were only 35% of the total nitrate budget. The second objective was to investigate the impact of sampling frequency and sampling location on understanding dynamics in water quality by degrading a year time series of seven parameters from three water quality monitoring stations to sampling frequencies ranging from 15 minutes to 28 days. In Morro Bay Estuary, the semi-diurnal tidal cycle was the maximum component frequency driving the variability of temperature, turbidity, and dissolved oxygen concentrations. For these parameters, asymptotes were reached and sampling frequencies greater than six hours did not explain the additional variation in the parameters sampled. Whereas, salinity, turbidity, and nitrate concentrations lacked an asymptote, and decreased sampling frequencies led to increased estimated error. Sampling water quality parameters every 28 days can lead to mean annual difference of 30 – 140 % from 15 minute sample annual mean. We recommend sampling frequencies should be selected to oversample the tidal signal to at least hourly frequencies to capture diel cycles and episodic events that contribute significantly to understanding the variability in the estuarine physical and biological dynamics.

The endemic eelgrass (Zostera marina) community of Morro Bay Estuary, located on the central coast of California, has experienced an estimated decline of 95% in occupied area (reduction of 344 acres to 20 acres) from 2008 to 2017 for reasons that are not yet definitively clear. One possible driver of degradation that has yet to be investigated is the role of herbicides from agricultural fields in the watershed that feeds into the estuary. Thus, the primary research goal of this project was to better understand temporal and spatial trends of herbicide use within the context of San Luis Obispo (SLO) County and Morro Bay Watershed by analyzing data of application by mass, area, and intensity to identify herbicides with the highest potential for local environmental pollution. California Pesticide Use Annual Summary Reports (PUASR) from the years 2000 to 2017 were used to obtain data for conducting a meta-analysis to estimate total herbicide application by weight within every township, range, and section for each of the eight selected herbicides: oxyfluorfen, glyphosate, diuron, chlorthal-dimethyl, simazine, napropamide, trifluralin, and oryzalin. A second goal was to select an analytical laboratory that would be best suited for herbicide analysis of estuary sediments to determine the presence, or lack thereof, of the eight selected herbicides. Criteria of consideration in laboratory selection included herbicides detection capabilities, detection/reporting limits, testing prices, chain of custody protocols, turnaround times, and laboratory site locations. The meta-analysis yielded results showing high herbicide application rates in SLO County with glyphosate, oxyfluorfen, and chlorthal-dimethyl being identified as three herbicides of elevated risk for local environmental contamination due high rates of use by mass, by area, and/or intensity during the study timeframe. Additionally, Morro Bay Watershed exhibited moderate rates of herbicide application with chlorthal-dimethyl and glyphosate being of highest risk for contamination and accumulation within the estuary because of high application rates by mass, by area, and/or intensity. Finally, Environmental Micro Analysis (EMA) and Primus Group, Inc. (PrimusLabs) were identified as the top candidates for analytical laboratory testing of Morro Bay Estuary sediment samples to be obtained and tested for the selected herbicides. These laboratories provide superior analytical capabilities of the eight herbicides, impressive reporting limits or lower detection limits, competitive testing prices for detecting multiple constituents in multiple samples, robust chain of custody protocols, options for quick turnaround times, and laboratory site locations within California.

Native to the world’s third-largest tropical rainforest, the indigenous people of West Papua, known as Papuan, have experienced substantial changes to their ecosystem over the last several decades, primarily to their water resources. As surface water has been a primary asset for drinking water consumption and their livelihoods for generations, the increase in pollution from expanding oil palm plantations impacts many lives. Receiving limited attention, disentangling this water injustice from power relations as a byproduct of the state-backed development, corporate-driven expansions, and consumer demand become pivotal to advocating for the indigenous community and their livelihoods. Therefore, this study explores integrating physical evidence of agricultural runoff from oil palm plantations and indigenous perceptions using hydro-social territories in a remote area in West Papua, Indonesia. Due to the lack of long-term investigations of the impact of water contamination in West Papua, a hydrological model will be used to assess the nature of the oil palm impact within the watershed. As deterioration in water quality is expected due to landscape changes, the indigenous perception of hydrological changes is crucial to determine how significant the impact is on local livelihoods. Semi-structured interviews will be used to study the perception of indigenous communities on water resources and threats of oil palm to their livelihood. The synthesis of those results will later be concluded using the hydro-social approach, involving a multi-scale analysis that includes Indonesian state and corporate actors through literature reviews from various sources (e.g., official documentation, corporate reports, and journals). This research will develop strategies to protect indigenous communities not yet impacted by large-scale changes in the watershed resulting from palm oil plantations.

No description available.