Groundwater is a crucial part of the hydrological cycle and is an important source for drinking water, irrigation and industry, particularly during droughts. With climate change, the hydrological variability is predicted to increase, making predictions for recharge and groundwater storage even more important to implement and to maintain sustainable water use. This study examines the importance of model spin-up in simulating recharge using the Hydrus-1D computer model. The focus is on two previously made Hydrus-1D models that represent end members in climate and hydrology; one which is a natural grassland in a semi-arid climate, while the other is a low impact development (LID) bioswale site in a Mediterranean climate. The main goal of this study is to characterize the range and causes of spin-up behavior as well as to analyze the extent of the effects that the spin-up process has on the recharge simulations. Although there has been some research on spin-up behavior for surface-water models, there is still a knowledge gap regarding the effects of model spin-up on vadose zone models simulating recharge. The initial conditions varied using three parameters for each of the two models: time (3, 15 and 30 years), initial moisture (θ = 0.1, 0.2 and 0.3) and precipitation (25% drier than historical data, historical 30-year data, 25% wetter than historical data). The output from these spin-ups were then used as initial conditions in simulating recharge using the 15-year models. The study found that the impact of spin-up is significant in the natural grassland site where there is a slow response between atmospheric forcings and recharge and where there is a relatively thick vadose zone. Especially spin-up time showed great variability and there is an inverse relationship between spin-up time and magnitude of recharge, where the longer spin-ups had lower recharge rates. Initial water content and precipitation did not result in different recharge amounts for the LID model. Length of spin-up only had very small differences in recharge for the LID models, indicating they are less sensitive to changes in initial spin-up parameters.

Boreal landscapes cover a large part of both Sweden and the northern hemisphere. The hydrology of the boreal landscape is complex, with several factors that can affect it in a physical and/or chemical manner. In the Krycklan catchment area, 68km2, located in northern Sweden close to Umeå, data has been collected at several sites giving both stream flow and water chemistry information. In 2017 samples from 34 sites were collected and analysed from ephemeral streams within the Krycklan catchment area for the first time ever.  In this project, data that has been collected from the ephemeral streams will be correlated with data from the perennial streams in the catchment area. There are several hypotheses at the start of this project that suggests that within the ephemeral streams the DOC will be lower, and the CO2 will be the same. The aim of the project is to find out if there are any patterns that differentiates the ephemeral streams from the perennial streams or if there are no patterns at all. Since there is not so much data available for the ephemeral streams, the conclusions that might be reached in this project won’t be completely reliable. However, if interesting patterns are found the project could expand in the future and more samples can be taken to use for more precise analyses. / Boreala landskap täcker en stor del av både Sverige och norra halvklotet. Det boreala landskapets hydrologi är komplext, med flera faktorer som kan påverka det på ett fysiskt och/eller kemiskt vis. I Krycklans avrinningsområde, 68 km2, beläget i norra Sverige nära Umeå, har data samlats in på flera platser som erbjuder data för både flöde och vattenkemi. År 2017 samlades prover från 34 efemära strömmar och analyserades för första gången inom Krycklans avrinningsområde. I det här projektet kommer data som samlats från de efemära strömmarna att korreleras med data från de konstanta vattendragen i avrinningsområdet. Det finns ett par hypoteser i början av detta projekt som tyder på att inom de efemära strömmarna kan DOC halter vara lägre och CO2 halter kommer att vara densamma. Syftet med projektet är att ta reda på om det finns några anmärkningsvärda skillnader mellan de efemära strömmarna och de konstanta vattendragen. Eftersom det inte finns så mycket data tillgänglig för de efemära strömmarna kommer de slutsatser som kan uppnås i detta projekt inte att vara helt tillförlitliga. Om intressanta mönster finns däremot kan projektet expandera i framtiden och fler prover kan tas för att användas för mer exakta analyser.

The percolation of water through waste rock dumps at mine sites can lead to the production of a leachate with high concentrations of dissolved metals, sulfate and nitrogen compounds. It is important to understand how water flows in waste rock dumps in order to predict the environmental impact of this leachate on recipients. The dynamics of percolation and leachate discharge are controlled by climatological conditions at the site, where relatively large flows in northern Sweden correspond to snowmelt during late Spring. Rock dumps are often tens of meters in height, resulting in an unsaturated water flow system through heterogeneous material. Hence, the simulation of leachate generation requires an accurate representation of the subsurface materials as well as the flow processes, where water flow in waste rock dumps is dominated by matrix flow with macropore flow being of secondary importance. Matrix flow is rather slow and may thus potentially yield relatively high concentrations of contaminants in the leachate, in response to precipitation and snow melt. This study uses Hydrus-1D to predict leachate generation from a small-scale waste rock dump in Kiruna in terms of discharge magnitude and timing. The 3-dimensional geometry of the waste rock dump is approximated by summing simulations from 1225 one-dimensional columns of different length, with a surface area of 1 m2 each. There are four output parameters that are compared between the model results and measured data: snow accumulation, water content, temperature, and discharge. There are some discrepancies between the model results and field measurements, most likely due to uncertainties in the input parameters (especially waste rock properties), limitations in the Hydrus-1D model (i.e. freeze-thaw dynamics), and assumptions that are used in constructing the conceptual model. For better agreement between model results and measured data, a new modelling approach is recommended, potentially using a different program than Hydrus-1D.

Groundwater flow and transport in deep crystalline rock is an important area of research. This is partly due to its relevance for constructing a long term repository for storing radioactive spent nuclear fuel in deep bedrock. Understanding the behavior of flow and transport processes in deep crystalline rock is crucial in developing a sustainable solution to this problem. This study aims to increase the understanding of how channel network models (CNM) can be applied to represent groundwater flow and solute transport in sparsely fractured crystalline rock under site specific conditions. A main objective was to determine how to incorporate structural and hydrogeological site characterization data in the construction of the CNMs. In addition to this, the associated key parameters of the CNMs were investigated to gain further understanding of model site application. To that end, a scripting approach with the python scripting library Pychan3d was used to create alternative channel network representations of a field site. A conceptual discrete fracture network (DFN) model was constructed using field site data obtained from a structural model of the fractures present at the site of the Tracer Retention Understanding Experiments (TRUE) - Block Scale at the Äspö Hard Rock Laboratory (HRL). This conceptual model was used as a base for constructing two different alternatives, denoted respectively as sparse and dense, of a CNM. The sparse CNM consisted of a limited amount of channels for each fracture, while the dense CNM acted as a DFN proxy, taking the full extent of the fracture areas into account and creating a dense, large network of flow channels for each fracture. In order to verify the performance of the generated CNMs, a reproduction of tracer tests performed at the same specific field site was attempted using a particle tracking technique. In addition to this, long term predictions of solute transport without the interference of the pumps used during the tracer tests were done in order to estimate transport time distributions. Pychan3d and the scripting approach was successfully used to create CNMs respecting specific conditions from the TRUE-Block Scale site. The sparse CNM was found to give very adequate flow and transport responses in most cases and to be relatively easier to calibrate than its dense counterpart. The long term transport predictions at the site according to the models seem to follow a channelized pattern, with only a few select paths for transport. The difficulties encountered in matching the dense CNM with the tracer tests most likely stem from difficulties in flow calibration, as well as certain key parameters being assigned too generically.

In 2012, the Swedish fortification agency started an environmental program for their real estate in northern Sweden. For the Boden garrison this meant an evaluation was needed for their storm water handling. The evaluation fell upon Grontmij AB in Boden. This thesis concerns the pollution from the storm water pipes into its recipient Lule River. Its aim was also to evaluate the areas for the event of a bigger oil spill, since there are many mechanical garages within the garrison. The pollution concerning oil was evaluated by calculating the flow in each outlet into the river, with different rain intensities. For other pollutants, the volumes of storm water each year, for every outlet were calculated. With concern for the snow melting process, it was also calculated for which period of the year would be interesting to keep an extra watch for pollutant concentrations and maximum flows. Results showed that for a 50-year period, none of the years would have had their peak flow because of the snow melt. The results for evaluation of an oil spill showed that none of the outlets were equipped for an accident of such sort, should it coincide with a rainfall of a high intensity. The results also showed that one of the outlets had an oil trap only dimensioned for rainfall of the lowest intensity. The calculating of pollutant volumes raises the concern for reliable data, but measures have already been taken to meet this concern.

The Geological Survey of Sweden (SGU) has initiated a project to calibrate models to simulategroundwater levels in monitoring wells of their Groundwater Network, based on a commission fromthe Swedish Government after experiencing historically low groundwater levels and shortage in 2016and 2017. A version of the HBV model with 4 parameters, focusing on calculating groundwaterrecharge and levels, was manually calibrated to 119 groundwater stations in 2017 and the modelresults were classified according to a ‘good’, ‘poor’ or ‘bad’ visual fit to observations. In this thesis,the process-based model CoupModel, which allows the user to freely setup a model structure, wasused to simulate groundwater levels. The objectives of this thesis were to evaluate the usability of theCoupModel in groundwater level simulations and forecasting, and compare the results to previoussimulations using the HBV model. 22 groundwater stations of fast and slow responding aquifers, distributed all over Sweden, wereused to simulate groundwater levels with the CoupModel. A model structure with 11 parameters tocalibrate was constructed to represent all groundwater stations. A split-sample test was performed withcalibration of 10,000 Monte Carlo simulations and validation of the 10 simulations with the highestNash-Sutcliffe efficiency (NSE). The NSE performance was highest, and consistent through calibration and validation, for fastresponding aquifers using the CoupModel, whereas the performance of slow responding aquifers waslower. Residual analysis showed periodicity with under- and overestimations for low and highgroundwater levels, respectively, indicating that the model structure is not sufficient in representing allgroundwater stations. No relationship existed between CoupModel performance and HBV calibrationperformance, topographic position, aquifer type, location or distance to climate station. The HBVperformance was lower than for the CoupModel, with residuals of larger spread and periodicity. The CoupModel can be used for simulation and forecasting of groundwater levels, but a newmodel structure or individual structures for all groundwater stations must be constructed. A sensitivityanalysis of the parameters in the model structure must be performed to study the systematic under- andoverestimations. / Grundvatten har en stor betydelse för att upprätthålla ekosystem och försörja människor meddricksvatten, där grundvattentillgång och nivåer beror av bland annat nederbörd, temperatur,snösmältning, växtupptag och antropogen påverkan på jord och mark. Förändringar i temperatur- ochnederbördsmönster på grund av klimatförändringar och en större vattenförbrukning påverkargrundvattennivåernas variationer inom och mellan år. Den här studien syftar till att undersöka hur ochi vilken uträckning den konceptuella modellen CoupModel kan användas för simulering ochprognostisering av grundvattennivåer, samt hur den står sig i relation till en annan, tidigare studeradmodell (HBV-modellen). Studiens relevans uppdagades hos Sveriges geologiska undersökning (SGU)i samband med historiskt låga grundvattennivåer under 2016-2017, genom initiering av ett projekt medmålet att kalibrera grundvattenmodeller till mätstationer i SGUs grundvattennät. Appliceringen avmodeller har stor samhällsnytta då förebyggande av och åtgärder mot låga grundvattennivåer kanplaneras och vidtas utifrån väderprognoser och klimatscenarier. En modellstruktur skapades i CoupModel och användes för att simulera grundvattennivåer i 22grundvattenstationer av olika karaktär och modellen kalibrerades och validerades mot observationer avgrundvattennivå. Resultatet av studien visade att CoupModel kan användas som verktyg försimulering och prognostisering av grundvattennivåer, men att modellstrukturen som användes behöverutvecklas. Systematisk över- och underestimering av observerade nivåer förkommer hos allasimuleringar och ingen relation kunde ses mellan modellens prestation och plats eller typ avgrundvattenstation. CoupModel presterade i de flesta fall bättre än HBV-modellen, men kräversamtidigt mer information om en grundvattenstations jordprofil och fler parametrar att kalibrera.

Dagvattnet från Märsta är belastat med bland annat tungmetaller och näringsämnen. Vattnet hamnar i Märstaån och transporteras vidare ut till Mälaren. Steningedalens våtmark är ett dammsystem som renar och fördröjer en del av Märstaåns flöde före transport ut mot Mälaren.   Syftet med detta självständiga arbete på kandidatnivå har varit att undersöka anläggningens reningsfunktion med hjälp av sedimentprovtagning. Sedimentprover har tagits vid in- och utloppet och en kemisk analys av dessa har utförts i ett ackrediterat laboratorium. Resultaten från in- och utloppet har jämförts för att se om det sker en minskning av föroreningar genom systemet. Fem sedimentfällor har placerats ut i delar av dammsystemet för att undersöka sedimentfördelningen och muddringsbehovet i anläggningen. Resultatet av studien visade att dammsystemet har en god vattenreningsfunktion med avseende på tungmetallerna bly, nickel, kadmium, krom, koppar och zink samt näringsämnet fosfor. Anläggningen har bedömts att vara i behov av muddring. / In Märsta, the storm water is contaminated with heavy metals and nutrients (nitrogen and phosphorus) among other pollutants. The water emits to the river Märstaån and further to the lake Mälaren. The wetland of Steningedalen is a pond system that delays part of the stream in Märstaån and purifies the water on its way through the system. This independent project is based on investigation of the purification functioning at Steningedalen wetland. The investigation has been done by sediment sampling and analysis. The samples were taken from the inlet and the outlet of the pond system. Chemical analysis has been made on these samples in an accredited laboratory. The results were compared in order to see if there is a trend through the system. Five sediment traps were placed in parts of the system to study the distribution of the sediment and the need of dredging. The results of the study have concluded that the stormwater pond system has a good water purification function with regard to heavy metals lead, nickel, cadmium, chromium, copper and and zinc aswell as the nutrient phosphorous. The study has also shown that the system is in need of dredging.

Mercury (Hg) which originates from global emissions to the atmosphere can deposit far away from the source. There is often a weak correlation between Hg deposition and concentrations in runoff, therefore catchment specific parameters might be of importance in controlling the amount of Hg ending up in watercourses and fish. Total mercury (THg) and methylmercury (MeHg) concentrations in watercourses are correlated to organic matter (OM), and in this study total organic carbon (TOC) is used as a proxy for OM. This study covers data from 125 watercourses in Sweden, and investigates the impact of e.g. Topographic Wetness Index (TWI), forest type, soil and bedrock types, deforestation and catchment size on the THg and MeHg concentrations as well as on the residuals from the regression between THg and TOC. Previous studies have found strong correlations between THg and OM as well as MeHg and OM but few previous studies have studied influences of catchment specific factors on THg and MeHg runoff concentrations with data of this large spatial and temporal scale. The catchment characteristics were extracted through ArcMap and projection to latent structures (PLS) models were created to evaluate what characteristics had the strongest influence on the variation in THg and MeHg concentrations as well as on the THg/TOC residuals. A strong correlation was found between THg and TOC, but a weaker one between MeHg and TOC. The MeHg concentrations were found to be dependent on variables which co-vary with TOC, as well as on latitude. The negative impact of latitude on MeHg concentrations could be due to methylation being temperature dependent or reflecting a spatial variation in Hg deposition from north to south of Sweden. Amount of deforestation was found to have an impact on the THg concentrations, indicating that deforestation leads to larger THg fluxes from soil to stream. The fact that variables measuring OM content in the streams were strongly influencing THg and MeHg concentrations, and the fact that few catchment characteristics were of importance, indicate the high importance of OM in explaining THg and MeHg also at this large spatial and temporal scale. / Studien sammanfattar hur halter av kvicksilver, och dess relation till organiskt material, i vattendrag påverkas av olika landskapsvariabler. Få tidigare studier har studerat hur kvicksilverhalten i vattendrag varierar beroende på avrinningsområdets karaktär i så stor skala, vad gäller antal områden och antal mätvärden, som i denna studie. Kvicksilver (Hg) är ett skadligt ämne för människor och natur, eftersom det i sin biotillgängliga form, metylkvicksilver (MeHg), är ett nervgift som kan orsaka stor skada på centrala nervsystemet. I de flesta vattendrag i Sverige är den uppmätta kvicksilverhalten i fisk högre än världshälsoorganisationens rekommenderade gränsvärden för fisk som föda. Kvicksilver härstammar från globala utsläpp till atmosfären som kan falla ned långt ifrån utsläppskällan. Då det ofta inte finns något rakt samband mellan kvicksilvernedfallet och de koncentrationer som återfinns i avrinnande vatten så kan områdesfaktorer och aktiviteter i de lokala avrinningsområdena ha stor betydelse för hur mycket kvicksilver som hamnar i våra ytvatten och sedan i fisken. Ett starkt samband har påvisats mellan mängden organiskt material i vattendrag och koncentrationen av totalkvicksilver (THg). I denna studie testas om sambandet mellan kvicksilver och organiskt material, mätt som total organiskt kol (TOC), kvarstår över lång tid (upp till 17 år) och hög rumslig upplösning (125 avrinningsområden). Eftersom ett relativt starkt samband återfanns fokuserade den här studien på att vidare utreda hur sambandet mellan THg och TOC, samt koncentrationer av MeHg, påverkas av områdesfaktorer i de olika avrinningsområdena. Det undersöktes hur skogstyp, jordarts- och bergartstyper, skogsavverkning, avrinningsområdets storlek samt Topographic Wetness Index (TWI, ett mått på hur topografi och markfuktighet är fördelat inom ett avrinningsområde), påverkar koncentrationer av total- och metylkvicksilver samt relationen mellan totalkvicksilver och organiskt material. Information om avrinningsområdena togs fram i GIS och statistiska modeller för hur områdesfaktorer påverkar kvicksilverkoncentrationer skapades genom PLS analyser (Projection to Latent Structures). Latitud visade sig ha en negativ påverkan på MeHg koncentrationerna; desto högre latitud desto mindre MeHg, vilket kan bero på att metylering är temperaturdriven process och/eller att reflektera en variation i Hg deposition från norra till södra Sverige. Studien kan sammanfattningsvis säga att inget samband hittades mellan de övriga landskaps-variablerna som undersökts i studien och kvicksilver koncentrationer.

This study focuses on soil hydrological parameters that are expected to be related to burn severity in forests; infiltration rate, soil moisture, grain size distribution and carbon content along a burn severity gradient in Västmanland Sweden, where a major fire occurred in 2014. Hälleskogsbrännan was divided into two burn severities: a moderate severity and a high severity, and a control area. Ten soil samples were taken for laboratory analyses at each severity level. Soil moisture and infiltration rate was measured in situ. Infiltration rates and soil moisture were highest in the most severely affected site, whereas fire effects on soil texture were insignificant. Soil organic carbon content was highest at the low fire severity site, followed by control and high severity fire sites. Inorganic carbon content followed the opposite trend. These results had clear trends but were insignificant, this call for more comprehensive sampling to separate possible confounding site effects.

Agriculture has been the backbone of the economy in Nigeria providing employment and source of livelihood for the increasing population and accounting for over half of the GDP of the Nigeria economy at independence in 1960. However, the role it plays in the regional and economic development of the country has diminished over the years due to the dominant role of the crude oil sector in the economy. With the increasing food demand in Nigeria, the country has available input natural resources and potential for increasing the volume of crop production towards meeting the food and nutritional requirement of the rapidly increasing population and guarantee food security in the country. The study was undertaken to analyse the effect of different factors and policies on the changes in trend of crop production and investigate the possible effect of water resources development on increased volume of agricultural crop production in Nigeria. The study revealed that there are opportunities for water resources development in the country through irrigation to supplement the water requirements and needs of farmers for agricultural production activities in many areas in the semi-arid and arid regions. Available data shows that there are available land and water resources that could be developed to support the production of food and agricultural development with opportunity for increased productivity. However, while the water resources are unevenly distributed in the country, there is need for the efficient use and management of the available water resources and increasing the productive use especially in the northern region of the country where there is increasing incidence of drought and competing need for water among the different sectors of the economy. The study also made possible recommendations for policy formulation to address the current problems facing the agricultural sector in conjunction with the requirement for the development of the water resources.