This study investigates the source of nutrients in an agricultural landscape in Kenya. Kapshoi furrow has its intake from Embobut River and flows through the village of Sibou until it reaches the plots in the lowland in Keu. The pH, electrical conductivity (EC), sediment transport, total nitrogen (N) mass flux and total phosphorus (P) mass flux all change when the furrow flows through the village. The most possible cause for the nutrients peaks is the farmers' goats, sheep and cows that walk freely in and around the furrow. This is counter to some existing local theories. The likely cause for the pH decrease and the EC increase are inflow of groundwater (springs) to the furrow. To secure safe drinking water it would be good to uphold the old rules in Sibou of (1) not to live in close proximity of the furrows and (2) not to bathe or do the dishes in the furrow water. This might be difficult due to a fast growing population.

The active layer constitutes an important subsystem of permafrost environments. Thermal andhydrological processes in the active layer determine local phenomena such as erosion, hydrologicaland ecosystem changes, and can have implications for the global carbon-climate feedback.Despite their importance for environmental and climate change, active layer dynamics are stillonly poorly understood. The importance of hydrology for active layer processes is generallywell acknowledged on a conceptual level, but the physical interdependencies between soil moisture,subsurface water flows and active layer depth are largely unresolved. This thesis usedstate-of-the-art numerical modeling to study the influence of ground surface temperature, soilmoisture content and advective heat flow on near-surface permafrost temperatures and activelayer depths. The investigation was performed for a dry, loess-covered river terrace in centralAdventdalen, Svalbard, and fed by high-resolution hydro-climatic field data for the period2000-2014. Nine scenarios were considered in order to independently test the influence ofdifferent initial soil moisture contents (6%, 12%, and 19%) and infiltration patterns (no infiltration,constant infiltration, and early summer peak infiltration). Results indicated that the permafrost-hydrological system at the study site is largely influenced by cryosuction processes due tostrong capillarity of the highly unsaturated soil. Zones of increased ice content developedprimarily near the permafrost table, creating a ‘transition zone’ between the lower part of theactive layer and the upper permafrost. Infiltration based on snow melt and summer precipitationwas found to be negligible for the seasonal active layer development. The active layer depthgenerally decreased with increasing initial soil moisture content due to a higher consumption oflatent heat. However, cryosuction into the permafrost table and water percolation could potentiallycounterbalance latent heat effects, at least in systems characterized by higher soil moisturecontents. Both model simulations and field observations showed a clear tendency of increasingactive layer depth during the study period, whereas inter-annual variations in active layer depthwere comparably small. Given the moisture migration into the ‘transition zone’, the modelresults further suggested that the site might be capable to buffer thaw and thus obscure increasingground surface temperatures to a certain degree. This could have implications for the suitabilityof active layer depth as a proper indicator for climate change.

A good understanding of the local and regional water cycle and how it is modified by landscape changes may help policymakers take the pertinent decisions in order to avoid adverse effects of future hydro–climatic changes. This knowledge is of particular interest in the most vulnerable areas of the world such as the African continent. In this context the aim of this project is to model hydrological responses to possible changes in climatic conditions in Lake Babati, northern Tanzania. For this reason a water balance model specially designed to simulate lake level changes was adapted to Lake Babati and calibrated with the available local meteorological and hydrological data record covering the last decades. The necessary ambient condition changes to produce a dry–out and an overflow of the lake were investigated and the response of the system to future IPCC climate change projections was studied. The results show that for instance a temperature change of less than 3ºC or a precipitation change of around 100 mm/year could eventually bring the lake from a dry–out situation to an overflow situation. Furthermore, the IPCC derived scenarios show a clear tendency of the lake to increase its volume and reach the overflow level in a relatively short time.

No description available.

Messinia is a region in Greece renowned for its rich nature, olive agriculture and water availability. In the light of increasing anthropogenic and climatic pressure, this study assessedlocal water resources in catchments in south western parts of the region. The main objectives were to evaluate the balance between supply and demand, the sustainability of current waterconsumption, capacity of further land use intensification and to review local water management. The method was dual with both quantitative (water balance calculations and linear modeling) and qualitative (interviews and a questionnaire survey) approaches.It was confirmed that, on an annual basis, rainfall is comparatively high, there is a surplus of water leaving the catchments and aquifers are “superfluous”. The climate however, brings seasonal imbalance and notable shortages during summer that affect operation of local actors, especially with agriculture and tourism being the principal water users. Unofficial sources indicated that current consumption may not be sustainable, either because of over-exploitation or climatic changes, but further studies are required to draw reliable conclusions. Modeling showed the importance of land management, that unconsidered water consumption may impact the water balance substantially but also that, while minimizing evapotranspiration,there is capacity of intensification if water withdrawals are increased. Considering accessibility, competitive interests and sustainability however, such development is not necessarily feasible.The municipal water management appeared to be well established and, given that measures are taken concerning for example stakeholder integration and regulation of private and agricultural consumption, there is capacity of handling increasing water stress. Finally, stressing the crucial role of freshwater availability, the study highlighted the importance of further hydrological research and thus the need for improved data quality, particularly regarding river discharge.

No description available.

In this study, GIS methods were used in order to evaluate different wetness indicators — topographic indices and airborne gamma radiation measurements — from their ability to distinguish wet areas from other areas. As a surrogate measure of extreme wetness, the occurrence of mires from land use maps were used. The evaluation of each wetness indicator was made in two ways. First, mire and non mire values for each measure was tested for similarity. Then, predicted mire maps were produced by defining mire area class limits (threshold values), which gave the same fraction of mire area in the catchments as in the land use maps. The predicted mire maps were then compared to the map showing mires from land use surveys. The best predictions were made by the drainage efficiency index (46.8% correct mires of all mire cells), which was proposed as an alternative to the ln(α/tanβ) index (the TOPMODEL index) and slope. This index quantified the downslope drainage ability for any point in the catchment, which is likely to be important for the wetness status. Mire predictions from K-40 gamma radiation were correlated to the different geological regions in the area and did not reproduce an accurate overall mire pattern. The TOPMODEL index class limits were strongly correlated to the fraction of mire area, which prevented it from being a good indicator of mires. It did not reproduce accurate amounts of area in the subbasins from a global threshold value. However, the general pattern of the predicted mires agreed relatively well with the pattern of actual mires from the land use map. / I en studie undersöktes förmågan hos olika mått på markfuktighet — topografiska index samt flyguppmätt naturlig gammastrålning från K-40 att särskilja våta områden från övrig mark. Som ett mått på extremt fuktig mark användes förekomsten av myrar från Gröna Kartan. Utvärderingen av de olika fuktighetsmåtten gjordes först genom att jämföra frekvenskurvorna för myrmark respektive övrig mark och kvantifiera skillnaden mellan dessa fördelningar för varje fuktighetsmått. Därefter uppskattades ett tröskelvärde för varje fuktighetsmått, vilket delade frekvensfördelningen i två klasser. Tröskelvärdet valdes så att förhållandet mellan arean i våt respektive torr klass blev densamma som mellan myrmark och övrig mark ur Gröna Kartan. Med utgångspunkt från dessa tröskelvärden framtogs kartor med simulerade myrar för varje fuktighetsmått, vilka jämfördes med myrarna i Gröna Kartan. De simulerade myrarna från ett topografiskt index som kvantifierade dräneringsförhållanden nedströms i terrängen gav bäst överensstämmelse med de verkliga myrarna (46.8% rätt klassade myrceller av det totala antalet myrceller). Simuleringen av myrar från K-40 gammastrålning var starkt beroende av berggrundstypen i området, och det övergripande mönstret gav ingen god överensstämmelse med Gröna Kartans myrar. Tröskelvärdena för ett av de topografiska index som granskades, ln(α/tanβ) index (TOPMODEL index), visade ett mycket tydligt beroende av andelen myr i området som simulerades, vilket gjorde att det svart att sätta ett gemensamt tröskelvärde for alla delområden i studien. Trots detta överensstämde myrmönstret från detta index i huvudsak med myrområdena från Gröna Kartan. / <p>Delar av examensarbetet publicerades senare som ”Water Resources Research technical note”: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2004WR003130</p>

Flow in fractured rocks has been intensively studied in the last decades, in part due to plans in manycountries to site repositories for high level nuclear waster in deep geologic formations. All investigated crystalline rocks have been found to be fractured and the majority of water flows through these fractures andfracture zones. Therefore, it is of interest to be able to understand and model flow rates, flow pathwaysand discharge through realistic rough-surfaced fractures. Conventional experiments using rock samples havedifficulty controlling and observing fracture properties, in particular the highly variable fracture aperturevoid space. Therefore, taking advantage of 3D printing technologies, two samples were created representinga constant and varying aperture fracture. This allows the properties of the fracture to be controlled andidentical geometries for both experiment and simulation to be prepared. Development of a laboratory experiment allowed for flow tests over different hydraulic gradients to be conducted through the printed samples.Discharge was numerically simulated through 9 single fracture cases, 5 of which have a constant aperture,assuming the Navier Stokes equations and using a computational fluid dynamics solver (OpenFOAM). Theresult of the simulation based on the Navier Stokes equations was within 5% of the experimental result forhydraulic gradients of 0.01 and 0.05, this suggests that the results from the experiment and simulation arereliable. In order to observe the transition from Darcy to non Darcy flow through a single fracture the hydraulic gradient was systematically increased. The results from both the experiment and the simulation werecompared to the simplified cubic law assumption using various estimates of aperture. Inertial forces influencethe discharge and have more importance on varying aperture geometry, therefore the transition to non Darcyflow in smooth apertures occurs at a higher hydraulic gradient. Calculation of the cubic law using the meanaperture value including zeros can reduce the difference between simulated discharge. A two-fracture systemwith one intersection was also simulated to investigate the influence of intersection geometry on discharge,which seems to be dependent on flow velocities, with low and high flows producing less variable discharge.Uncertainties between numerical simulation and laboratory experiments can be reduced by using 3D printedfracture networks, hence they can be a beneficial for understanding complex interactions that can happenwithin networks.

Avrinningens förändring i tid och rum beror av såväl klimat och årstid som av avrinningsområdets fysikaliska egenskaper. Kunskap om förändringar i avrinningsdynamiken är av stor vikt vid konstruktion av hydrologiska modeller. Avrinningsområdena i denna studie ligger inom NOPEX-projektets försöksregion. Regionen är ungefär 50 x 100 km2 och ligger till största delen nordväst om Uppsala. Områdena varierade i storlek från 0,45 till 11,5 km2. Tre av områdena var rena skogsavrinningsområden. De övriga två områdena var avsevärt större och utgjordes till största delen av skogs- respektive jordbruksmark. Den studerade perioden sträcker sig från juli 1994 till juli 1995. Avrinningsdynamiken studerades genom jämförelser av hydrogram, vattenbalanser, fördröjning snösmältning – avrinning, förändringen av avrinningens andel av det till området tillförda vattnet och analys av recessionskurvor. Dynamiska vattenmagasin har uppskattats genom integration av recessionsekvationer och magasinskoefficienter har uppskattats. Skillnaderna i avrinningsdynamik mellan områdena var i vissa fall avsevärda trots likartade fysikaliska egenskaper. Det minsta skogdominerade avrinningsområdet uppvisade en mycket avvikande avrinningsdynamik med stora avrinningstoppar under tidig höst, en vattenbalans med mycket hög avrinning, liten fördröjning snösmältning – avrinning och snabb recession. De övriga tre skogsdominerade områdena hade inte lika accentuerade skillnader i avrinningsdynamiken. Det av jordbruksmark dominerade området intog även det en särställning med litet och långsamt gensvar på nederbörd och en recessionskurva vars form inte liknade något annat område. Analysresultaten i detta arbete gav fingervisningar om vilka processer och förlopp som är av stor vikt vid beskrivning av avrinningsdynamiken i hydrologiska avrinningsmodeller. Den ibland mycket stora rumsliga variationen i avrinningsdynamik tydliggör de representativitetsproblem som är förknippade med användandet av regionala modellparametrar. / Changes of runoff in time and space are dependent on climate and season as well as on the physical properties of the catchment. Knowledge of changes in runoff dynamics in time and space is of great importance in the construction of hydrological models. The five catchments in this study were located in the NOPEX region. The region is approximately 50 x 100 km2 and it is located northwest of Uppsala. The studied catchments varied in size from 0.45 to 11.5 km2. Three small catchments were forested. The other catchments were larger and were dominated by woodlands and farmlands. The studied period extended from July 1994 to July 1995. The runoff dynamics were studied through comparisons of hydrographs, water balances, delays between snowmelt and runoff, variations in the runoff fraction of the water input to the area and analysis of recession curves. The dynamic groundwater storage was estimated by integrating the recession equations. The storage coefficient was also estimated. The differences in runoff dynamics between the catchments were considerable in some cases despite physical similarities. The smallest wooded catchment showed very different runoff dynamics with large runoff peakflows during early fall, a very large runoff in the waterbalance, a short delay between snowmelt and runoff and a quick recession rate. The differences in runoff dynamics between the remaining three wooded catchments were not as accentuated. The catchment dominated by farmland held a unique position with a slow runoff response to precipitation and a recession curve with a different shape. The results of this study gave pointers to the processes that are of great importance in describing the runoff dynamics in hydrologic runoff models. The sometimes large variation in runoff dynamics in space elucidates the problems with representativity associated with the use of regional model parameters.

I denna uppsats har den laterala och den longitudinella dispersionen studerats i en grusås, (Finnerödjaåsen) med hjälp av spårämnesmärkning. Spårämnet, NaI injicerades i ett grundvattenrör. Jodidkoncentrationen i grundvattnet mättes i injiceringsröret, i sju grundvattenrör placerade tvärs över åsen och i ett rör 50 meter nedströms injiceringsröret. För att bestämma den laterala och den longitudinella dispersionskoefficienten användes en förenklad modell som förutsätter laminärt flöde i ett homogent medium. Modellen visade god överensstämmelse med försöksresultaten från Finnerödjaåsen. Den laterala dispersionen beräknades till 2.4 m2/dygn. Den longitudinella dispersionen visade sig vara mycket större i åsens kärna, ända upp till 260 m2/dygn än någon meter från kärnan ut mot åskanten där dispersionen i genomsnitt var 16 m2/dygn. Hastigheten hos grundvattnet i åsens kärna var ungefär dubbelt så stor som i övriga åsen och troligtvis transporteras största delen av flödet i en liten del av åsens mitt. / The lateral and longitudinal dispersion of groundwater was studied in a gravel ridge, (Finnerödjaåsen) in the central part of southern Sweden. NaI was injected into a groundwater tube. The iodine concentration in the groundwater was then measured in the injection tube, in seven groundwater tubes placed in a transverse row 1,5-4 m apart 20 m downstream the injection tube and in one tube 50 m downstream the injection tube. The coefficients of lateral and longitudinal dispersion were determined by using a model assuming laminate flow in a homogeneous medium. For the gravel ridge examined, there was a good fit between the experimental data and this model. The lateral dispersion was found to be 2,4 m2/day. The longitudinal dispersion was much larger in the narrow passage in the middle of the ridge, 260 m2/day, than in the marginal zones of the ridge, 16 m2/day. The flow velocity of the groundwater in the middle of the ridge was about twice as large as the flow velocity in the rest of the ridge, i.e. the bulk flow of groundwater occured in the middle of the ridge.