The thesis deals with hydrological conditions in a proglacial environment, focusing on the development of glacial lakes and the assessment of their susceptibility to outburst. The study site is the Adygine glacier-moraine complex located in the north-facing valley of the Kyrgyz Ridge, northern Tien Shan, Kyrgyzstan, at an altitude of 3400-4200 m a.s.l. In the past 50 years, the receding glacier allowed formation of several lakes, which form a three-level cascade and are fed by glacier meltwater. Below the glacier, there is a complex of several generations of moraines, through which the glacier meltwater is routed downstream. The aims of the work were to evaluate the development of individual lakes, their susceptibility to sudden outburst and possible triggers, to estimate the probable development of the site in the future, to analyse the hydrological regime of the lakes and to obtain basic information on the subsurface flow of water from the site to the stream. For the purposes of assessing the development of the lakes, the data obtained in the field (geodetic surveying of a shore line, bathymetric measurements), as well as satellite and aerial images were used. Fluctuation of lake water level was monitored by pressure sensors and the processing of this data allowed to analyse the hydrological...

Sediment records of two Italian subalpine lakes (Lake Garda and Lake Ledro) were analyzed in order to reconstruct their ecological evolution over the past several hundred years. A multi-proxy and multi-site approach was applied in order to disentangle the effects of local anthropogenic forcings, such as nutrients, and climate impacts on the two lakes and their catchments. Biological indicators (sub-fossil pigments, diatoms and Cladocera) were used to reconstruct changes in the aquatic food web and to define the lake reference conditions, while geochemical methods, i.e. wavelength-dispersive X-ray fluorescence spectroscopy (WD-XRF), were used to provide quantitative information on the different physical or chemical processes affecting both lake and catchment systems. Sub-fossil pigments and diatoms, together with their respective inferred TP values, suggested very stable oligotrophic conditions in both lakes until the 1960s. The period following was affected by nutrient enrichment, which led to a drastic shift in the phytoplanktonic community. The response of sub-fossil pigments and diatoms to major climatic anomalies such as the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA) were not pronounced, and the taxonomic composition remained relatively stable. On the contrary, these proxies showed an indirect response to climate variability since the beginning of the nutrient enrichment phase in the 1960s. In Lake Garda, the winter temperature regulates the water column mixing, which in its turn controls the degree of nutrient fertilization of the entire water column, and the related phytoplankton growth. In Lake Ledro a rapid reorganization of planktonic diatoms was observed only during the temperature recovery after the LIA, while recent temperature effects are masked by the prevailing nutrient effects. In Lake Garda, Cladocera remains responded in quantitative and qualitative terms to climatic changes, whereas in Lake Ledro they appeared to be mainly affected by variations in hydrological regimes, i.e. flood events. Cladocera remains corroborated the nutrient enrichment after the 1960s in both lakes as inferred by diatoms and pigments. In Lake Garda, the geochemical data showed a pronounced shift in elemental composition since the mid-1900s, when major elements and lithogenic tracers started to decrease, while some elements related to redox conditions and other (contaminant) trace elements increased. The general trends since the mid-1900s agree with the biological records. However, some differences recorded in the two different basins of Lake Garda reflected the effects of local conditions, both related to hydrology and sedimentation patterns. Lake Ledro showed higher short-term variability for most elements, even though some features were comparable to Lake Garda. The geochemical record of Lake Ledro revealed a major influence of human-induced lake-level fluctuations and catchment properties. This paleolimnological study allows us to place temporally restricted limnological surveys into a longer-term secular perspective, which is highly valuable for the definition of lake reference conditions. Because the restoration targets are usually based on the lake reference conditions, this study highlighted also the necessity to pay particular attention to the lake-specific sensitivity patterns. The multi-proxy and multi-site approach showed that the lake conditions of large and deep lakes in northern Italy, such as Lake Garda, are mainly driven by nutrient enrichment and/or climate change. In contrast, smaller lakes with larger catchment areas, such as Lake Ledro, are seemingly more impacted by conditions and processes occurring in the drainage basin.

This diploma thesis deals with morphometric analysis and hydrological regime of Skalnaté pleso lake and Hincové Oká lakes, especially the lake level fluctuation, during the period 2011 - 2014. One of the tasks was the bathymetric mapping of observed locations. For Hincové Oká lakes was it the first mapping of bathymetry at all. The hydrological regime and lake level fluctuation regime of observed locations shows interesting differences from the other Tatra lakes whose hydrological regime is controlled by precipitation amounts. The annual culmination of Hincové Oká lakes (the largest lake) is shifted into the spring caused by melting snowpack. When there is no rainfall for a couple of days Skalnaté pleso lake often dries up, even during summer months, when levels of most Tatra lakes reach their maximum values. However summer drying is shortterm. Lake level fluctuation regime is very dynamic. After a strong rainfall event its level rises very steeply, up to 0,14 m per hour. Powered by TCPDF (www.tcpdf.org)

Dams and reservoirs play an important role in the Swedish energy system, and a large number of rivers are today regulated. How to combine the ecological and economic interests in the regulation of these rivers is a growing concern for stakeholders and authorities. The aim of this study was to develop a conceptual environmentally- oriented dam release plan that combines economic and ecological needs for the Lower Långan Natura 2000 area as well as evaluating how the water stage of the reservoir Lake Landösjön would change with a more environmentally oriented flow regime. Three flow scenarios were established: (0) Current flow regime, (1) EU demand for good ecological status which requires changes in discharge dynamics, and (2) the environmental design flow. The Dundee hydrological regime assessment method (DHRAM) was used to evaluate the hydrological alterations for each of the three scenarios. Scenario 0 exhibited the largest alteration from natural flow and the results from the DHRAM analysis indicated on high risk of ecological impact in the river system. Scenario 1 met EU’s demand of good ecological status but the water stage in Lake Landösjön exceeded the maximum allowed legal limit. Scenario 2 comprised a flow regime encompassing both economic and ecological interests and is the most realistic scenario for improving ecology in the Lower Långan River. In conclusion in order to meet EU demand of good ecological status a change in upstream regulation is needed. / Vattenkraften spelar en viktig roll i det svenska energisystemet och i dagsläget är ett stor antal sjöar och vattendrag reglerade. Ett växande problem för aktörer inom vattenkraft och myndigheter är hur ekonomiska och ekologiska intressen skall kombineras för att åstadkomma en mer hållbar vattenanvändning.  Långans avrinningsområde ligger i nordvästra Jämtland och har en total yta på 2 287 km2 . Inom avrinningsområdet återfinns fyra regleringsmagasin: Burvattnet, Stora Mjölkvattnet, Korsvattnet och Landösjön. I den sydöstra delen av avrinningsområdet ligger nedre Långans Natura 2000-område vilket har undantagits från vattenkraftsutbyggnad då det innehåller ett antal viktiga naturtyper. Ett centralt begrepp i Natura 2000 är gynnsam bevarandestatus vilket innebär att medlemsstaterna är skyldiga att gynnsam bevarandestatus bibehålls alternativt återställs till naturligt tillstånd. Då gynnsam bevarandestatus är kopplad till rådande hydrologiska förhållanden gäller miljökvalitetsnormen God ekologisk status. I dagsläget klassificeras nedre Långans Natura 2000-område med otillfredsställande ekologisk status. För att nedre Långans skall uppnå EUs krav på god ekologisk status krävs det att flödet anpassas till mer naturliga flödes förhållanden.  Syftet med denna studie var att utveckla miljöanpassade flöden enligt tre scenarier. Dessa scenarier med miljöanpassade flöden har konsekvensbeskrivits där huvudmålet har varit att förbättra den ekologiska statusen av nedre Långan samt utvärderat hur vattennivån i Landösjön påverkas om dessa flöden tas i bruk. Följande scenarier fastställdes: (0) Nuvarande flödesregim, (1) EU: s efterfrågan på god ekologisk status vilket kräver att flödet efterliknar det naturliga oreglerade flödet, och (2) kompromissflödet, ett mellanting mellan scenario 0 och 1. Den hydrologiska avvikelsen av scenarierna bedömdes med hjälp av The Dundee Hydrological Regime Alteration Method (DHRAM). DHRAM analysen består av en ett femgradigt system som mäter graden av mänsklig påverkan på naturliga flödesregimen relaterat till scenario 0-2. och är kompatibelt med EU:s ramdirektivet för vatten.  Resultatet från DHRAM-analysen uppvisade att Scenario 0 har den största förändringen jämtemot det naturliga flödet och vattendraget löper stor risk för ekologisk påverkan. Scenario 1 uppfyllde EU: s krav på god ekologisk status, men med detta flöde översteg dämningsgränsen i Landösjön med 2m under april till juni. Scenario 2 är baseras på både ekonomiska och ekologiska intressen Utifrån de testade scenariona kunde följande slutsatser dras: (1) scenario 2 är det mest realistiska scenariot för att förbättra ekologin i nedre Långan, (2) för att möta EU: s krav på god ekologisk status krävs en förändring av uppströms liggande regleringsmagasin

Summary Fresh water availability and distribution have been declining over time due to population increase, climate change and variability, emerging new demands due to economic growth, and changing consumption patterns. Spatial and temporal changes in environmental changes, such as climate and land use/cover (LULC) dynamics have an enormous impact on water availability. Food and energy security, urbanization and industrial growth, as well as climate change (CC) will pose critical challenges on water resources. Climate variability and change may affect both the supply and demand sides of the balance, and thus add to the challenges. Land-cover changes are vastly prominent in the developing countries that are characterized by agriculture-based economies and rapidly increasing human population. The consequent changes in water availability and increase in per capita water demand will adversely affect the food, water and energy security of those countries. Therefore, evaluating the response of the catchment to environmental changes is crucial in the critical part of the basin for sustainable water resource management and development. In particular, assessing the contribution of individual LULC classes to changes in water balance components is vital for effective water and land resource management, and for mitigation of climate change impacts. The dynamic water balance of a catchment is analyzed by hydrological models that consider spatio-temporal catchment characteristics. As a result, hydrological models have become indispensable tools for the study of hydrological processes and the impacts of environmental stressors on the hydrologic system. Physically-based distributed hydrological models are able to explicitly account for the spatial variability of hydrological process, catchment characteristics such as climatic parameters, and land use/cover changes. For improved illustration of physical processes in space and time, the distributed hydrological models need serially complete and homogenized rainfall and temperature data. However, observed rainfall and temperature data are neither serially complete nor homogeneous, particularly in developing countries. Using inhomogeneous climatological data inputs to hydrological models affects the output magnitude of climate and land use/cover change impacts and, hence, climate change adaptation. The Nile River Basin, one of the transboundary river flows through 11 riparian states, serves the livelihoods of millions of people in the basin (nearly 20 per cent of the African population) and covers one-tenth of the land cover of Africa. The basin is characterized by high population growth and high temporal variability in the river flow and rainfall patterns. The Blue Nile river basin, which contributes 62% of the annual main Nile flow, has faced serious land degradation. This has led to increased soil erosion and loss of soil fertility. The most overwhelming challenge that the basin faces is food insecurity caused by subsistence farming and rain-fed agriculture (over 70% of the basin’s population), together with high rainfall variability. Drought and floods are also critical issues in the Blue Nile basin, with the potential for exacerbation by environmental changes. Understanding how LULC and climate changes influence basin hydrology will therefore enable decision makers to introduce policies aimed at reducing the detrimental effects of future environmental changes on water resources. Understanding types and impacts of major environmental stressors in representative and critical regions of the basin is crucial for developing of effective response strategies for sustainable land- and water-resource management in the Eastern Nile Basin in general, and at the Tana and Beles watersheds in particular. In this study, serially completed and homogenized rainfall and temperature dataset are maintained from 1980 to 2013 to fill-in the gap which characterized previous studies on trend analyses. The new hydroclimatic data revealed that the climate the study region has become wetter and warmer. The proportional contribution of main rainy season rainfall to annual total rainfall has increased. This might result in high runoff and ultimately flooding as well as erosion and sedimentation in the source region of the Blue Nile, and siltation in the downstream reservoirs unless soil and water conservation measures are taking place. In the Tana sub-basin, it is found that expansion of cultivation land and decline in woody shrub are the major contributors to the rise in surface run-off and to the decline in the groundwater component from 1986 to 2010. Similarly, decline of woodland and expansion of cultivation land are found to be the major contributors to the increase in surface run-off and water yield. They also contributed to the decrease in groundwater and actual evapotranspiration components in the Beles watershed. Increased run-off and reduced baseflow and actual evapotranspiration would have negative impacts on water resources, especially in relation to erosion and sedimentation in the upper Blue Nile River Basin. As a result, expansion of cultivation land and decline in woody shrub/woodland appear to be major environmental stressors affecting local water resources. GCMs simulated near-future annual total rainfall and average temperature were used to investigate the sensitivity of the catchment to near-future CC. The results showed an increase in streamflow in the annual and the main rainy season, but decrease in the dry period when compared to the baseline period. Catchment response for future LULC scenario showed opposite effect to that of near-future CC. The combined effects of climate change and LULC dynamics can be quite different from the effects resulting from LULC or CC alone. At the outlet of the Tana watershed, streamflow response is amplified under concurrent land cover and climate change scenarios compared to the baseline scenario; but the streamflow has an augmenting response at the outlet of the Beles watershed under future climate change and land use scenarios compared to that of current period. The important inference from these findings is that it could be possible to alleviate intense floods or droughts due to future climate change by planning LULC to achieve particular hydrological effects of land cover in the basin. Continuing expansion of cultivation land and decrease in natural vegetation, coupled with increased rainfall due to climate change, would result in high surface runoff in the main rainy season, which would subsequently increase flooding, erosion and sedimentation in already degraded lands. Sound mitigation measures should therefore be applied to reduce these adverse environmental consequences. On the other hand, the simulated climate and land-use change impacts on the Tana watershed hydrological regime might increase the availability of streamflow to be harnessed by water-storage structures. In conclusion, the present study has developed an innovative approach to identify the major environmental stressors of critical source region of the Blue Nile River in order to effectively managing the water resources and climate risk. Understanding the catchment responses to environmental changes improves sustainability of the water resources management particularly given that the hydropower and the irrigation schemes are recently established for energy and food security.:TABLE OF CONTENTS LIST OF ABBREVIATIONS LIST OF FIGURES LIST OF TABLES 1. General Introduction 2. The study area 3. Gap Filling and Homogenization of Climatological Datasets in the Headwater Region of the Upper Blue Nile Basin, Ethiopia Abstract 3.1. Introduction 3.1.1. Data 3.2. Methodology 3.2.1. Quality control and gap filling 3.2.2. Homogenization 3.3. Results and Discussion 3.3.1. Gap filling 3.3.2. Homogeneity 3.3.3. Verification of the homogenization 3.3.4. Impact of homogenization on the rainfall and temperature series 3.4. Conclusions Acknowledgements 4. Revisiting trend analysis of hydroclimatic data in the Upper Blue Nile basin based on homogenized data Abstract 4.1 Introduction 4.2 Data and Methodology 4. 2.1 Data 4. 2.2 Linear trend 4. 2.3 Trend magnitude 4.3 Results and Discussions 4.3.1. Linear mean climate trends 4.3.1.1. Rainfall 4.3.1.2. Maximum Temperature (Tmax) 4.3.1.3. Minimum Temperature (Tmin) 4.3.1.4. Mean temperature (Tmean) 4.3.1.5. Diurnal temperature range (DTR) 4.3.1.6. Streamflow 4.3.2. Effect of homogenization on Tmax, Tmin, Tmean and DTR linear trends 4.3.3. Linear extreme climate trends 4.3.1. Temperature 4.3.2. Precipitation 4.4 Conclusions Acknowledgements 5. Recent Changes in Land Use/Cover in the Headwater Region of the Upper Blue Nile Basin, Ethiopia 85 Abstract 5.1 Introduction 5.2 Materials and Methods 5.2.1 Data used and image pre-processing 5.2.2 Classification accuracy assessment 5.2.3 Extent and rate of change 5.2.4 Detecting the most systematic transitions (dominant signals of change) 5.4 Results and Discussion 5.4.1 Accuracy assessment 5.4.2 Extent and rate of LULC changes 5.4.3 Rate of land use and land cover change 5.4.4 Detection of most systematic transitions 5.5 Conclusions Acknowledgements 6. Hydrological Responses to Land use/cover Changes in the Tana and Beles Watersheds, the Upper Blue Nile, Ethiopia Abstract 6.1 Introduction 6.2 Method 6.2.1 Hydrological modeling 6.2.2 Partial least squares regression 6.3 Results and Discussion 6.3.1 Calibration and validation of SWAT 6.3.2 Impacts of LULC changes on hydrology at the basin scale 6.3.3 Contribution of changes in individual LULCs to hydrological components 6.4 Conclusions Acknowledgements 7. Combined Impact of Climate and Land Use Changes on Hydrology in the Tana and Beles Sub-Basins, Upper Blue Nile, Ethiopia Abstract 7.1 Introduction 7.2 Methodology 7.2.1 Simulation 7.2.2 Climate change scenarios 7.2.3 LULC change scenarios 7.3 Results and Discussion 7.3.1 Future versus current LULC impact on the basin hydrology 7.3.2 Future versus baseline climate 7.3.3 Impact of combined future climate and LULC changes on hydrology 7.4 Uncertainties and Limitations 7.5 Conclusions Acknowledgements 8. Overall Conclusions, Recommendations and Future Research Directions 8.1. Overall Conclusions 8.2 Recommendations and Directions for further research References

The Maputaland Coastal Plain in Kwa Zulu-Natal is covered by aeolian sands . According to the national wetland delineation manual delineating wetlands in this area is complex due to problematic wetland soils. The aim of this study was to classify and describe the vegetation of the different zones of the wetland systems to determine the main drivers of the plant communities. The understanding of these complex ecosystems could assist in wetland delineation. Twenty wetlands from five wetland systems were surveyed. The vegetation zones of each wetland were sampled and basic environmental data were collected. The results from this study indicate that different plant species assemblages are characteristic for the wetland zones. However, zone delineation using vegetation composition varies between the different wetland systems, and should be evaluated according to the system in question. The major determinants of the vegetation communities in wetlands on the MCP are the substrate type and hydrological regime / Environmental Sciences / M.Sc. (Environmental Management)

Water quality was one of the biggest problems of environment in beginning of 90. of 20th century in the Czech republic. Since 90. the level of water quality was in czech rivers rapidly better. Mainly in big rivers have accomplished great changes. The small rivers haven't notice that rapid changes. The Czech republic, after entrance to the European Union have committed to comply with Directive 91/271/EEC reduce urban waste water and which should have big influence to water quality also in small rivers. During 90. industry technology, agriculture, cleaning technology of waste water etc. reached big development. Therefore the presumption is higher quality of water in the Czech republic since 90. Goal of the thesis is comparison of results from 1999-2000 with results from 2012- 2014 from Mladoticky brook catchment, which is lined up to small river catchments (79,77km2 ). From this comparison there is obvious trend, if conditions of the water quality are really better or not since 90. [33] Since 2012 to 2014 were taken 12 times samples from 11 profiles of water from Mladotice brook catchment and they were consequential chemically analyzed. The samples were evaluated according to ČSN 757221 and compared with results from 1999-2000. From comparison with data 1999-2000 and 2012-2014 was confirmed the...

It analyzes the relationship between territorial dynamics in land use and changes in the hydrological regime in the Central region of Costa Rica. A comparison is made between two years and the results showed that this process has been intense from one year to another. The urban and industrial heavy pressure on the most fertile soils of the country, has led to changes inthe hydrological regime of the two major sub-basins: Virilla and Grande de San Ramón, both of which constitute the Basin of Grande de Tarcoles River. The sub-basin of the Virilla Rivercan not store rainfall, especially considering that a large percentage of its area is covered byland uses of urban type. In contrast, the sub-basin of the Grande de San Ramón River retains a higher percentage of water, having land uses dominated by pasture, crops, and forests. In synthesis, several land uses increase their area, especially urban areas, with the major exception of the forest area which was reduced considerably. / Se analiza la relación entre la dinámica territorial en el uso de la tierra con respecto a los cambios en el régimen hidrológico en la región central de Costa Rica. Se hace una comparación entre dos años y se encontró que tal proceso ha sido muy intenso de un año al otro. La fuerte presión urbanística e industrial sobre los suelos más fértiles del país, ha provocado modificaciones en el régimen hidrológico de las dos principales subcuencas hidrográficas: Virilla y Grande de SanRamón, ambas conforman la cuenca del río Grande de Tárcoles. La subcuenca del río Virilla no logra almacenar el agua pluvial, especialmente si se considera que un alto porcentaje de su área está cubierta por usos de tierra de tipo urbano. Por el contrario, la subcuenca del río Grande de San Ramón logra retener un mayor porcentaje de aguas, al tener usos de la tierra dominados por pastos, cultivos y bosque. En síntesis, varios de los usos de la tierra incrementan su área, en especial el área urbana, con la gran excepción del área de bosques que se redujo considerablemente.

The retention potential of landscapes, along with the water regime of spring areas, are important hydrological topics of research, particularly in the current context of increasing extreme drought frequencies. The present work is focused on monitoring the mountain peat bogs, which, due to their overall frequency of occurrence in the spring area of the Vydra river, represent a significant constituent of the rainfall-runoff process of the area of interest. The specific hydropedological features of the organogenous soils (Histosol type soil) provide the high retention potential of the area, however, the influence of these soils on the runoff process is determined by complex physicogeographical factors. The general opinion on the hydrological function of the peat bogs has changed in recent years and the most important factor in the runoff formation in the mountain area of the Šumava Mts. is now thought to be the actual saturation of the headwater, which is predominantly composed of hydromorphic and organogenous soils. The organogenous soils are significant water reservoirs and have an important impact on the landscape. However, they may also intensify the extreme values of the watercourses during extreme precipitation events. The fundamental part of this work focuses on detailed observations of the...

The Maputaland Coastal Plain in Kwa Zulu-Natal is covered by aeolian sands . According to the national wetland delineation manual delineating wetlands in this area is complex due to problematic wetland soils. The aim of this study was to classify and describe the vegetation of the different zones of the wetland systems to determine the main drivers of the plant communities. The understanding of these complex ecosystems could assist in wetland delineation. Twenty wetlands from five wetland systems were surveyed. The vegetation zones of each wetland were sampled and basic environmental data were collected. The results from this study indicate that different plant species assemblages are characteristic for the wetland zones. However, zone delineation using vegetation composition varies between the different wetland systems, and should be evaluated according to the system in question. The major determinants of the vegetation communities in wetlands on the MCP are the substrate type and hydrological regime / Environmental Sciences / M.Sc. (Environmental Management)