In this study, semi-distributed hydrological model studies were carried out with the Mike11 model in Yuvacik dam Basin. The basin with a drainage area of 257.8 km2 is located in 12 km South East of Izmit city in T&uuml / rkiye. The basin is divided into three sub-basins named as Kirazdere, Kazandere and Serindere where each sub-basin is represented by its own characteristics. The largest peaks of inflow were observed when the storm events occur due to both snowmelt and rain. Therefore, observed flows for the period of 2001-2006 were grouped as daily and hourly storm events according to the event types such as rainfall, snowmelt or mixed events. Rainfall- Runoff Model (NAM) module of the model was used for the simulation of daily snowmelt and rain on snow events and Unit Hydrograph Method (UHM) module was used for the simulation of hourly rainfall events. A new methodology is suggested for the determination of Curve Number (CN) of the sub-basins by using the fractional area and topographic index values combined with hourly model simulations. The resulting CN values were used in the UHM module v and the suggested CN approach has been validated with the classical SCS-CN approach with GIS analysis. As a result of the study, the parameters of each sub-basin are calibrated with hourly and daily model simulations. The resulting flows are compared with the observed flows where model efficiency is tested with visual and statistical evaluations. The modeling studies give promising results for the computation of runoff during different seasons of a year.

Accurate forecasts of future regional temperature and rainfall patterns in many regions largely depend on characterizing anthropogenic trends in tropical Pacific climate. However, strong interannual to decadal-scale tropical Pacific climate variability, combined with sparse spatial and temporal coverage of instrumental climate datasets in this region, have obscured potential anthropogenic climate signals in the tropical Pacific. In this dissertation, I present sea-surface temperature (SST) and salinity proxy records that span over the 20th century using living corals from several islands in the central tropical Pacific. I reconstruct the SST proxy records via coral Sr/Ca, that are combined with coral oxygen isotopic (d18O) records to quantify changes in seawater d18O (hereafter d18Osw) as a proxy for salinity. Chapter 2 investigates the spatial and temporal character of SST and d18Osw-based salinity trends in the central tropical Pacific from 1972-1998, as revealed by corals from Palmyra (6ºN, 162ºW), Fanning (4ºN, 159ºW) and Christmas (2ºN, 157ºW) Islands. The late 20th century SST proxy records exhibit warming trends that are larger towards the equator, in line with a weakening of equatorial Pacific upwelling over this period. Freshening trends revealed by the salinity proxy records are larger at those sites most affected by the Inter-Tropical Convergence Zone (ITCZ), suggesting a strengthening and/or an equatorward shift of the ITCZ. Taken together, the late 20th century SST and salinity proxy records document warming and freshening trends that are consistent with a trend towards a weakened tropical Pacific zonal SST gradient under continued anthropogenic forcing. Chapter 3 characterizes the signatures of natural and anthropogenic variability in central tropical Pacific SST and d18Osw-based salinity over the course of 20th century using century-long coral proxy records from Palmyra. On interannual timescales, the SST proxy record from Palmyra tracks El Niño-Southern Oscillation (ENSO) variability. The salinity proxy record tracks eastern Pacific-centered ENSO events but is poorly correlated to central Pacific-centered ENSO events - the result of profound differences in precipitation and ocean advection that occur during the two types of ENSO. On decadal timescales, the coral SST proxy record is significantly correlated to the North Pacific Gyre Oscillation (NPGO), suggesting that strong dynamical links exist between the central tropical Pacific and the North Pacific. The salinity proxy record is significantly correlated to the Pacific Decadal Oscillation (PDO), but poorly correlated to the NPGO, suggesting that, as was the case with ENSO, these two modes of Pacific decadal climate variability have unique impacts on equatorial precipitation and ocean advection. However, the most striking feature of the salinity proxy record is a prominent late 20th century freshening trend that is likely related to anthropogenic climate change. Taken together, the coral data provide key constraints on tropical Pacific climate trends, and when used in combination with model simulations of 21st century climate, can be used to improve projections of regional climate in areas affected by tropical Pacific climate variability.

Light Detection and Ranging (Lidar) is a remote sensing technique that provides high resolution range measurements between the laser scanner and Earth’s topography. These range measurements are mapped as 3D point cloud with high accuracy (< 0.1 meters). Depending on the geometry of the illuminated surfaces on earth one or more backscattered echoes are recorded for every pulse emitted by the laser scanner. Lidar has the advantage of being able to create elevation surfaces in 3D, while also having information about the intensity of the returned pulse at each point, thus it can be treated as a spatial and as a spectral data system. The 3D elevation attributes of Lidar data are used in this study to identify possible water surface points quickly and efficiently. The approach incorporates the use of Laplacian curvature computed via wavelets where the wavelets are the first and second order derivatives of a Gaussian kernel. In computer science, a kd-tree is a space-partitioning data structure used for organizing points in a k dimensional space. The 3D point cloud is segmented by using a kd-tree and following this segmentation the neighborhood of each point is identified and Laplacian curvature is computed at each point record. A combination of positive curvature values and elevation measures is used to determine the threshold for identifying possible water surface points in the point cloud. The efficiency and accurate localization of the extracted water surface points are demonstrated by using the Lidar data for Williamson County in Texas. Six different test sites are identified and the results are compared against high resolution imagery. The resulting point features mapped accurately on streams and other water surfaces in the test sites. The combination of curvature and elevation filtering allowed the procedure to omit roads and bridges in the test sites and only identify points that belonged to streams, small ponds and floodplains. This procedure shows the capability of Lidar data for water surface mapping thus providing valuable datasets for a number of applications in geomorphology, hydrology and hydraulics. / text

This dissertation explores the coupling between radiative and three-dimensional dynamical processes in the atmosphere of Titan, and their impact on the seasonal climate and recent paleoclimate. First, a simple calculation is used to demonstrate the atmospheric attenuation on the distribution of insolation. The maximum diurnal-mean surface insolation does not reach the polar regions in summertime, and this impacts both surface temperatures and their destabilizing effect on the atmosphere. Second, a detailed two-stream, fully non-gray radiative transfer model, written specifically for Titan but with high flexibility, is used to calculate radiative fluxes and the associated heating rates. This model reproduces Titan's temperature structure from the surface through the stratopause, over nearly six decades of pressure. Additionally, a physics parameterizations package is developed for Titan, in part based on similar methods from Earth atmospheric models, for use in a Titan general circulation model (GCM). Simulations with this model, including Titan's methane cycle, reproduce two important observational constraints---Titan's temperature profile and atmospheric superrotation---that have proven difficult to satisfy simultaneously for previous models. Simulations with the observed distribution of seas are used to examine the resulting distribution of cloud activity, atmospheric humidity, and temperatures, and show that these are consistent with dry mid- and low-latitudes, while the observed polar temperatures are reproduced as a consequence of evaporative cooling. Analysis of the surface energy budget shows that turbulent fluxes react to the surface insolation, confirming the importance of its distribution. Finally, the GCM is used to simulate Titan's climate during snapshots over the past 42 kyr that capture the amplitude range of variations in eccentricity and longitude of perihelion. The results show that the atmosphere is largely insensitive to orbital forcing, and that it invariably transports methane poleward, suggesting Titan's low-latitudes have been deserts for at least hundreds of thousands of years. In detail, seasonal asymmetries do affect the distribution of methane, moving methane to the pole with the weaker summer, though orbital variations do not imply a long-period asymmetry. If the timescale for the atmosphere to transport the surface liquid reservoir is sufficiently short, this explains the observed north-south dichotomy of lakes and seas.

Irrigation plays an extremely important role in agriculture but climate change is predicted to modify climate patterns with potentially devastating consequences for irrigation. Potential impacts and adaptations are known, but not how implementation strategies may be implemented at the individual irrigation scheme level. Using a case study approach and qualitative research methods this thesis describes the Bwanje Valley Irrigation Scheme (BVIS), Malawi in order to explain how water is managed. Subsequently, historical adaptations are described in order to draw conclusions concerning the vulnerability of the BVIS under normal and extreme hydrological conditions. The BVIS is vulnerable in all conditions because it utilizes a common pool resource. As water supply decreases, irrigation water management becomes less and less equitable which makes the system extremely sensitive to changes in water supply. Capacity to adapt to climate change is limited to funding provided by external agencies which currently limit adaptations to reactive changes

Tiriamojo darbo objektas: Minijos upės baseinas. Tiriamojo darbo tikslas: atlikti Minijos upės baseino hidrologinių duomenų analizę, apskaičiuoti pagrindines hidrologines charakteristikas bei įvertinti nuotėkio kaitos tendencijas. Tiriamojo darbo uždaviniai: 1. surinkti Minijos upės baseino hidrologinius stebėjimų duomenis; 2. aptarti hidrologiniams skaičiavimams naudojamas programines įrangas; 3. išanalizuoti Minijos upės baseino surinktus hidrologinius duomenis ir įvertinti jų patikimumą; 4. atlikti surinktų hidrologinių duomenų analizę, panaudojant įvairią programinę įrangą. Tiriamojo darbo metodika: Minijos upės ties Kartena hidrologiniai stebėjimų duomenys išrinkti iš hidrologijos metraščių nuo 1954 iki 2010 metų. Literatūros apžvalgos skyrius rašomas referatyviai, analizuojant kitų mokslininkų atliktus tyrimus bei naudojamus metodus. Išsamiai išanalizuojama naudojama programinė įranga, apskaičiuojamos hidrologinės charakteristikos, sutvarkomi gauti rezultatai, daromos išvados. Tiriamojo darbo rezultatai: 1. Naudojant programinę įrangą „HYFRAN“ nustatyta, kad maksimalius vandens debitus geriausiai aprašo Weibull ekstreminių reikšmių skirstinys, o minimalius – Gumbel skirstinys. 2. Naudojant keturis bazinio nuotėkio indekso nustatymo metodus, nustatyta, kad tinkamiausias tam yra Anglijos hidrologijos instituto sukurtas metodas, kuris naudojamas programinėje įrangoje „HYDROTOOLS“. Nustatytas už 1954-2010 metų laikotarpį bazinio nuotėkio indeksas Minijos upei lygus 0,49... [toliau žr. visą tekstą] / Object of the research: the Minija river watershed. Aim of the research: to perform a hydrological data analysis of the Minija river watershed, to calculate the basic hydrological characteristics and evaluate the runoff trends. Objectives of the research: 1. To collect the hydrological monitoring data of the river watershed; 2. To discuss the software used for hydrological calculations; 3. To analyze the collected hydrological data of the Minija river watershed and assess their reliability; 4. To analyze the collected hydrological data by using different software. Methods of the research: the hydrological monitoring data of the Minija river (near Kartena) watershed were taken from annual Hydrological Data Books for the period of 1954-2010. The chapter on the reference sources is written by citing them and analyzing the survey carried out by other scientists and the research methods used. The used software is thoroughly analyzed, the hydrological characteristics are calculated, the results are arranged, and conclusions are drawn. Results of the research: 1. By using the software “HYFRAN” it was founded that the maximum water flow rate is best described by Weibull distribution of extreme values whereas the minimum water flow rate is best described by Gumbel distribution. 2. Using the four basic methods of determining flow index showed that the best method is developed by England’s Hydrological Institute and is used in the “HYDROTOOLS” software. It was estimated that the... [to full text]

Linkages between the controls on depressional storage and catchment streamflow response were examined in a wetland dominated basin in the Canadian Prairie Pothole region through a combination of field monitoring and modelling. Snowmelt, surface storage, water table elevation, atmospheric fluxes, and streamflow were monitored during spring snowmelt and summer in a 1 km2 sub-catchment containing a semi-permanent pond complex connected via an intermittent stream. Snow accumulation in the basin in spring of the 2013 study year was the largest in the 24-year record. Rainfall totals in 2013 were close to the long term average, though June was an anomalously wet month. The water budget of the pond complex indicates that there was a significant subsurface contribution to surface storage, in contrast to previous studies in this region. Following snowmelt, subsurface connectivity occurred between uplands and the stream network due to activation of the effective transmission zone in areas where the water table was located near the ground surface, allowing significant lateral movement of water into the stream network. Modelling results suggest there was significant infiltration into upland soils during the study period and that upland ponds are an important consideration for accurately simulating catchment discharge. The flux of groundwater to the wetland complex during periods of subsurface connectivity was also important for maintaining and re-establishing surface connectivity and streamflow. As the observed period of surface and subsurface hydrological connectivity was one of the longest on record in the catchment due to very wet conditions, the results of this study denote observations of the wet extremes of the hydrological regime important for proper understanding, modelling, and prediction of streamflow in the region.

Huvudsyftet var att ta reda på vad förskolebarn kan och tänker kring vattnets kretslopp och vattnets betydelse för allt liv på jorden. Samtidigt syftade undersökningen till att ta reda på pedagogernas arbetssätt och tankar kring dem. Undersökningen har genomförts med hjälp av kvalitativa intervjuer med såväl pedagoger som barn. Intervjuerna har spelats in och sedan transkribetats för att därefter analyseras. Resultatet av undersökningen visar att barnen har god kännedom om vattnets kretslopp och vattnets betydelse för livet på jorden. De kan de stora dragen i kretsloppet, men saknar vissa kunskaper vilket hindrar dem att beskriva kretsloppet i detalj. Resultatet visar också att pedagogernas arbetssätt varit gynnsamma för barnens inlärningsprocess. En av flera slutsatser som kan dras är att barn i svenska förskolor förefaller ha en hög kunskapsnivå vilket tyder på att den svenska förskolan håller god kvalitet. Det är också tydligt att pedagogernas val av arbetssätt har stor betydelse för barnens inlärning. / The main purpose of the survey was to find out what preschool children know and think about the hydrological circle and the importance of water for every form of life on Earth. At the same time, the survey aimed to find out which way the preschool teachers chose to work with the children and how they had been planning and thinking about it. The survey was implemented through qualitative interviews with pedagogues as well as children. The interviews were recorded and thereafter transcribed for later analysis. The results of the survey show that the children have good knowledge of the hydrological circle and the importance of water for life on Earth. They know the hydrological circle in general but lack some knowledge which prevents them from describing the circle in detail. The results also show that the way of work the pedagogues have chosen have been good for the learning process of the children. One of several conclusions is that children in Swedish preschools seem to have a high level of knowledge, which suggests that the Swedish preschool is one of high quality. It's also obvious that the way of work the pedagogues choose is of big importance for the learning process of the children.

Anthropogenic disruptions in the form of hydrological alterations, such as dam construction and the associated water diversions are a cause of much upheaval to local and regional ecosystems. Lake 626 within the Experimental Lakes Area of north-west Ontario, along with its downstream wetlands, 626A and 626B are one such system. Construction of a dam at the L626 inflow has completely restricted water flow, reducing and reshaping the watershed, increasing water retention time, and decreasing outflow into the wetlands. This study investigates the state of each wetland through physical and geochemical characterization during the first year following the diversion. Previous studies have found that hydrological diversions in wetlands can lower water table levels, altering soil chemistry and producing a shift in floral and faunal communities. Ultimate consequences involve significant loss of wetland area through conversion to upland habitat. This provides a model for climatic warming scenarios, wherein sustained drought conditions can produce the same result. Boreal wetlands are surprising fragile ecosystems that store massive quantities of carbon and are at risk of releasing it in such situations. One study showed that an extended summer drought in an otherwise average year with above average precipitation produced losses of 90 g C/m2 over the course of the year. Maintenance of reduced-flow in wetlands 626A and 626B is expected to convert the system into a carbon source and reduce overall wetland area. Radiocarbon dating has revealed that following deglaciation, both 626A and 626B basins were open water wetlands, depositing limnic peat for about 3200 and 1300 years respectively. Each site then transitioned into open sedge dominated fen – 626B to the present and 626A until about 2.5 ka BP when Sphagnum began to develop. Wetland 626B is decidedly an open shrub/sedge fen, supporting Myrica gale, Chamaedaphne calyculata and Carex rostrata / lasiocarpa communities. Wetland 626A is a bog/fen complex, sharing similar communities in the fen areas, but housing a large, centrally located bog of shrub species overlying Sphagnum hummocks. Tritium values in 626A were similar to cosmic background levels, indicating that recharge of basal pore water has not occurred in at least 60 years. Tritium in 626B was much higher, suggesting a substantial difference in hydrology or peat hydraulic conductivity between the basins. Measurement of DOC profiles showed high concentrations in near-surface water, reaching over 80 mg/L, and dropping to about 20 mg/L at maximum depths. An opposite trend was seen for DIC and CH4 profiles which increased concentration with depth (25 – 70 mg/L DIC; 75 – 700 μmol/L CH4). Isotopically however, 13C signatures from basal DIC were more positive while signatures from CH4 were typically more negative (-6 ‰ to +4 ‰ DIC; -57 ‰ to -73 ‰ CH4). Breakdown of DOC by LC-OCD showed high concentrations of humic substances and low molecular weight neutrals. The origin of humic substances in surface water became more pedogenic with increasing distance from the L626 outflow, indicating the influence of decaying wetland vegetation on the DOC of adjacent water. A comparison between contemporary and future characterization of boreal peatlands under drought-like conditions will provide a better understanding of the impacts suffered by wetlands during hydrological alterations. The high sensitivity of wetlands to changing hydrology should also provide a measure for gauging the effects of long term climate warming. This will assist in the development of environmental policies to better govern both the establishment of water diversions and the multitude of other practices leading to climate change.

Tracking and quantifying hydrologic change in urbanizing watersheds is a complex problem which can vary spatially and temporally throughout the effective catchment area as change occurs. Hydromodification due to urbanization usually results in a larger peak event stream discharge, a change in typical event volume, a reduced lag time between rainfall and stream discharge events, and a more complex falling hydrograph. Recently extracted Environment Canada data have allowed the creation of a high resolution instantaneous stream flow dataset dating to the late 1960s for many Ontario gauge stations. Hydrometric data were obtained for fifteen urban and semi-urban catchments within Southern Ontario ranging in size from ~50km² to 300 km² with urbanized land use assemblages varying from <5% to 80%. Utilizing automated methods, each individual runoff event from the hydrographic record was identified and characterized. Temporal changes to urban land area, land use, and road length were quantified for each watershed from aerial photography spanning the period of record at approximately 8 year intervals allowing identified trends in event hydrograph parameters to be correlated quantitatively with the alteration of the catchment over time. <br> Increasing trends in event peak discharge were identified in all but one study catchment. Event volume was found to be consistently increasing in most of the urban watershed, while trends in event duration were observed but with no clear increasing or decreasing trend. The lack of consistent trends in the timing and distribution of flow during runoff events suggest that build-out, drainage network design, and stormwater management systems play differing roles in the neighbouring urban catchments. Changes to flood recurrence intervals through the period of urbanization were also investigated; peak magnitude of high frequency events is affected to a greater extent than low frequency or flood events. The relative change in return frequency distribution is not consistent between catchments, also the degree of alteration can differ between various recurrence intervals at a gauge. Peak discharge of some return periods appeared to decrease with urban development suggesting that the increased detention brought with urban stormwater management systems have effectively offset the increased runoff due to additional impervious area and improved drainage efficiency. A consistent relationship defining the change in geomorphically significant return periods (i.e. channel forming flow) with urbanization was identified in neighbouring urban catchments.