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V Sloveniji se zaradi edinstvene geografske lege na izredno majhnem prostoru prepletajo najrazličnejši dejavniki in vplivi sosednjih naravnih enot, ki puščajo sledi na geomorfometričnih, podnebnih in hidroloških lastnostih ter značilnostih pokrovnosti in rabe tal po posameznih hidrografskih območjih. S pomočjo zelo dobro razvitega in strukturiranega sistema šifriranja padavinskih/hidrografskih območij in uvozom pred pripravljenih prostorskih baz podatkov je določevanje iskanih značilnosti porečij z uporabo geografskih informacijskih sistemov razmeroma enostavno. V diplomski nalogi so izračunane in predstavljene osnovne morfometrične lastnosti in značilne rabe tal, povprečna letna količina prejetih padavin (1980-2010), numerična organiziranost rečnih sistemov ter erozijska faktorja LS in R za hidrografska območja v Sloveniji na 3. nivoju. Tako pripravljeni podatki so podlaga za nadaljnje primerjalne analize, hidrološke študije ter hidrološko modeliranje. V nadaljevanju smo naredili primerjavo rezultatov lastnosti med posameznimi območji, ki pripadajo istemu glavnemu porečju. Narejena je tudi analiza medsebojne odvisnosti izbranih lastnosti porečij s pomočjo Pearsonovega koeficienta korelacije. Rezultati oz. lastnosti hidrografskih območij so v veliki večini pokazali veliko odvisnost od geografske lege. Višje ležeča območja, ki se nahajajo na severnem in zahodnem delu Slovenije (Julijske Alpe), izkazujejo sorazmeroma precej višje povprečne vrednosti geomorfometričnih lastnosti kot območja, ki segajo v panonsko ravnino. Obenem pa po rezultatih erozijskih faktorjev RUSLE (LS, R) sodijo med območja v Evropski Uniji z najvišjimi vrednostmi faktorjev za določevanje stopnje letne erozije. Due to its unique geographical location and extremely small area, various factors and influencing factors of neighbouring geographical landscapes are intertwined in Slovenia. This in turn, affects the geomorphometric, climatic and hydrological features, as well as the land cover and land use on each hydrographic unit/area. In favour of a very well developed and structured Slovenian watershed coding system and with the use pre-prepared spatial databases in geographic information systems, the determination of watershed characteristics is relatively simple. In the diploma thesis, the basic morphometric characteristics and typical land uses, average annual precipitation (1980-2010), stream order and erosion factors LS and R are calculated and presented for each Slovenian hydrographic unit on the 3rd level. So prepared data are the basis for further comparative analyses and hydrological studies and modelling. Furthermore, we compared the results of characteristics between individual hydrographic areas belonging to the same main watershed. Additionally, an analysis of the dependence of individual watershed characteristics using the Pearson correlation coefficient was conducted. The results of the characteristics of the hydrographic areas showed, in the vast majority, a high dependence on the geographical location and a large influence of the geographical landscape to which they belong. Higher areas located in the northern and western part of Slovenia (Julian Alps) showed relatively higher average values of geomorphometric characteristics than areas belonging to the Pannonian plain. According to the results of erosion factors RUSLE (LS, R), the Alps are also one of the areas in the European Union with the highest values of factors for determining the soil erosion rate.

Analiziranje razlik srednje temperature zraka glede na različne uprabljene metode merjenja ima pomembno vlogo v razumevanju značilnosti posameznih načinov zbiranja podatkov in različnih uporabljenih računskih metod v hidroligiji in hidrološkem modeliranju, kjer je srednja dnevna temperatura zraka eden izmed glavnih vhodnih podatkov. V nalogi so izračunane srednje dnevne temperature po različnih metodah na območju Slovenije v 10-letnem obdobju (2010-2020). Analiza razlik v temperaturi med uporabljenimi metodami za določanje srednje dnevne temperature je narejena s pomočjo programskega orodja R za 33 klimatoloških postaj. Za vsako izmed njih smo izračunali tudi povprečne absolutne napake, Pearsonove koeficiente korelacije in pripadajoče p-vrednostu. Rezultati kažejo značilne razlike med aritmetično vrednostjo in izračunano srednjo dnevno temperaturo zraka po različnih metodah na vseh obravnavanih postajah. Kljub temu lahko zaključimo, da je razlika najmanjša pri metodi, ki se že uporablja za izračun srednjih dnevnih temperatur v Republiki Sloveniji. Narejena je bila tudi analiza razlik izračunov srednjih temperatur zraka glede na različne načine odčitavanja vhodnih podatkov, ki je pokazala, da so te razlike manjše kot razlike zaradi uporabe različnih metod izračunov, so pa tudi te statistično značilne. Analysis of mean air temperature differences obtained using various measuring methods has an important role in understanding of characteristics of particular measuring method as well as using these methods in hydrology and hydrological modeling, where mean daily air temperature is one of the main input data. In this research, we calculated mean daily air temperatures in Slovenia for the last 10 years (2010-2020) using different methods. Analysis of differences among different mean air temperature calculating methods was performed in R programming language for 33 climatic stations. For each one of them we calculated mean absolute error, Pearson's correlation coefficient and corresponding p-value. The results show that there are characteristic differences between the arithmetic value and the calculated mean daily air temperature obtained using different methods for all considered station. Nevertheless, we can conclude that the difference is the smallest in case of method, which is already in use to calculate mean air temperatures in the Republic of Slovenia. In addition, an analysis of temperature differences according to different methods of the input data acquisition was performed, which showed that these differences are smaller compared to the differences obtained by using different calculation methods, but still statistically significant.

V diplomski nalogi smo obravnavali izračun površinskega odtoka s povirnega dela porečja Gradaščice. Hidrološko študijo porečja Gradaščice smo izdelali s pomočjo programskega orodja HEC-HMS. Prikazali smo pripravo potrebnih vhodnih podatkov za izdelavo hidrološkega modela porečja in predstavili nekatere zakonitosti, ki so pomembne za osnovno razumevanje formiranja površinskega odtoka. S prosto dostopnim programom SAGA-GIS, smo določili topografske značilnosti porečja, rabo tal, geološko in pedološko sestavo tal na obravnavanem območju. Na podlagi teh lastnosti smo ocenili parametre za izračun padavinskih izgub ter transformacije padavin v površinski odtok. Za ta namen smo uporabili teorijo hidrograma enote (HE). Poleg tega smo izvedli tudi terenske meritve pretokov na iztokih s podporečij, ki smo jih določili glede na šifrant padavinskih območij vodotokov. Izdelan hidrološki model smo umerili in preverili s pomočjo izbranih padavinskih dogodkov in merjenih pretokov. Z ročnim spreminjanjem parametrov smo poskušali določiti tisto kombinacijo parametrov, pri katerih bi dobili najboljše ujemanje med merjenimi in modeliranimi vrednostmi pretokov. Umerjanje in validacijo smo izvedli z upoštevanjem podatkov z vodomerne postaje Dvor. Za najustreznejšo se je izkazala Clarkova metoda HE, pri kateri je bilo prej omenjeno odstopanje najmanjše. Nekoliko slabše rezultate smo dobili pri uporabi Snyderjeve metode HE, medtem ko je metoda SCS HE dala najslabše rezultate. Za porečje Gradaščice se je umerjeni parameter CN gibal med 65 in 72 za tri podporečja, ki smo jih določili v procesu priprave podatkov za hidrološko modeliranje. Pri validaciji hidrološkega modela smo ugotovili, da ima na odstopanje med meritvami in modeliranimi vrednostmi pretokov vpliv tudi predhodna namočenost tal. Z uporabo umerjenega in validiranega hidrološkega modela smo določili tudi pretoke z 10-, 50- in100-letno povratno dobo. Kot vhodni podatek smo upoštevali sintetični histogram padavin, pri katerem smo upoštevali tudi porazdeljenost padavin znotraj padavinskega dogodka. Modelirane vrednosti konic pretokov smo primerjali tudi z rezultati verjetnostnih analiz. In this graduation thesis we discuss runoff modelling from the upper part of the Gradaščica river basin. Hydrological study was performed using hydrological model HEC-HMS. This thesis presents the preparation of required inputs for hydrologic model and some basic concepts of runoff modelling, which are important for understanding of the runoff characteristics. Using freely available computer program SAGA-GIS, we defined topographical characteristics, land use, geological and pedagogical soil structure of the upper Gradaščica river basin. This data helped us to evaluate parameters of precipitation loss and transformation precipitation runoff methods. Unit hydrograph (UH) theory was used for runoff modelling. Moreover, discharge measurements at river sub-basins which were defined by the watershed coding system were also performed in the scope of the thesis. The hydrological model was calibrated and validated using the measured rainfall and discharge data. Using manual calibration we tried to obtain the combination of parameters that gives the best correspondence between measurements and modelled discharge values. The calibration and validation process was performed using discharge data from the Dvor gauging station. Clark UH method yielded the best results and was selected as the most suitable method of unit hydrograph methodology. Snyder UH method yielded somewhat worse results. Furthermore, the SCS UH gave the worst correspondence between measured and modelled data. The CN parameter for the upper Gradaščica river basin was estimated to be from 65 to 72 for the three river sub-basins (calibrated values of the parameters), which we were defined in the process of hydrological modelling and data preparation. During validation process of the hydrological model we found that antecedent precipitation conditions have influence on the differences between measurements and modelled discharge values. Using calibrated and validated hydrological model we also defined hydrographs with 10-, 50- and 100-years return period. For the input data we used synthetic histogram precipitation and temporal precipitation distribution was also taken into account. Modelled peak discharge values were also compared with flood frequency analysis results.

Diplomska naloga obravnava vodno bilanco in njene člene ter program SIMPEL, namenjen takim izračunom. Namen ustvarjalcev programa je bil zmanjšati zahtevnost izračunavanja členov vodne bilance ter narediti hidrološki program, namenjen širšemu krogu uporabnikov. V prvem delu naloge smo predstavili osnovne člene vodne bilance ter sam program SIMPEL in njegovo delovanje. Razložili smo, kateri so potrebni začetni podatki in kam ter v kakšni obliki jih moramo vnašati. Nato smo podrobneje predstavili metode za izračun evapotranspiracije (ETp), in sicer Haude, Thornthwaite, Blaney/Criddle, Turc, Penman, Makkink, Wendling za obalna območja, Penman/Montheith za iglaste gozdove, Penman/Montheith – EPIC. Opisali smo tudi model veder, na principu katerega deluje program ter predstavili metode, s katerimi izračuna površinski odtok. V praktičnem delu naloge smo s pomočjo programa SIMPEL naredili izračun vodne bilance porečja reke Tolminke. Prikazane so izračunane vrednosti ETp in površinskega odtoka za ‘mokro’ leto 2009 in ‘suho’ leto 2011. Naredili smo primerjavo modeliranih in izmerjenih vrednosti ter s pomočjo koeficienta Nash-Sutcliffe ocenili učinkovitost modela. Izkaže se, da poda model zadovoljive rezultate pri izračunu ETp, pri izračunu površinskega odtoka pa ga je težko zadovoljivo umeriti, kar je pogost problem hidroloških modelov. The thesis deals with a general explanation of water balance, its components, and SIMPEL software designed for water balance calculations. The aim of the creators of the software was to reduce the complexity of calculations and to create a hydrological program designed for a wide range of users. In the first part of the thesis, there is a general explanation of water balance and its components and a description of SIMPEL software. We described the necessary input data as well as where and in what form to insert them. Then metods for calculating evapotranspiration (ETp) e.g. the Haude, Thornthwaite, Blanex/Criddle, Turc, Penman, Makkink, Wendling for costal areas, Penman/Monteith for coniferous woods and Penman/monteith – EPIC are descriped. The bucket model which is the basis for calculation of the surface runoff is also introduced. In the practical part of the thesis we calculated water balance for the catchment of Tolminka river using SIMPEL software. We compare the calculated values of ETp and surface runoff for one ‘wet’ year 2009 and one ‘dry’ year 2011. We compared measured and calculated values and assessed the predictive power of the model with Nash-Sutcliffe coefficient. The results demonstrate that model for calculations of ETp returned satisfactory results. However, it is difficult to satisfactory calibrate the model of surface runoff, which is often the problem of hydrological models.

Ekosistem je največja enota, ki opisuje procese, ki potekajo med neživo in živo naravo. Ta je sestavljen iz manjših ekosistemov, med katere spada tudi vodni ekosistem. V tej diplomski nalogi obravnavamo vodni ekosistem dveh jezer z vplivnim območjem. Za ugotavljanje kvalitete vode v jezerih Mola in Klivnik smo preučili proces evtrofikacije, ki ogroža ravnovesje v stoječih vodah. Na hitrost evtrofikacije vpliva več dejavnikov, ki jih delimo na naravne in antropogene. Stopnjo evtrofikacije najlažje določimo preko količine hranil v vodi, od katerih sta najpomembnejša fosfor ter dušik. Količine fosforja in dušika smo izračunali iz dveh virov. Prvi del količine pride v jezero preko kanalizacijskih odpadnih voda, drugi pa z vodami, ki se v jezero stekajo z vplivnega območja. Izračunane koncentracije fosforja in dušika v jezerih smo primerjali z meritvami, ki jih je opravila Agencija Republike Slovenije za okolje. Izračuni koncentracij so večinoma večji od dejanskih meritev. Do večjih odstopanj je prišlo pri koncentraciji fosforja, kjer so nekateri rezultati nekajkrat večji od izmerjene vrednosti. Pri dušiku je ta razlika manjša in lahko trdimo, da je izračun koncentracije dušika bolj natančen. Na podlagi stopnje evtrofikacije bi lahko v večini obravnavanega obdobja akumulaciji umestili med evtrofna jezera. Ker pa se določa stopnjo na podlagi izmerjenih vrednosti, ju umestimo med mezotrofna jezera. Na jezeru Klivnik antropogeni vplivi prispevajo 51 % količine fosforja, na jezeru Mola pa 56 %. Antropogeni vplivi imajo manjši vpliv na koncentracijo dušika in na Klivniku prispevajo 32 %, na jezeru Mola pa 37 % celotne koncentracije. Ecosystem describes the processes that take place between nonliving and living nature. The ecosystem is composed of smaller ecosystems, which include water ecosystems. In this diploma thesis water ecosystem represented by two lakes and theirs influence area will be discussed. We evaluated the quality of the water in the lakes Mola and Klivnik. The eutrophication process, which is the main threat to biodiversity in stagnant water, was examined. The speed of eutrophication is affected by several factors which can be classified as natural or anthropogenic. The degree of eutrophication can be determined by the quantity of nutrients in the water. The effect on eutrophication is dominated by two elements: phosphorus and nitrogen. The nutrients enter the lakes from two sources: by the sewage waste water and by runoff water from the influence area. The calculated concentration of phosphorus and nitrogen was compared with measurements performed by the Slovenian Environment Agency. Calculated concentrations are generally higher than measurements. Greater differences were observed for phosphorous concentrations. Therefore, the calculation of nitrogen concentrations is probably more accurate. Based on calculated values we could classify the lakes as eutrophic during most of the inspected period. However, based on measurements, which are more precise, the lakes are mesotrophic. For lake Klivnik the anthropogenic factors contribute 51 %, whereas for lake Mola they are responsible for 56 % of total phosphorous concentrations. Anthropogenic factors contribute to 32 % of total nitrogen on lake Klivnik and to 37 % of total nitrogen concentrations on lake Mola.

V diplomskem delu smo obravnavali analizo poplavnih valov vzdolž reke Save. V uvodnem delu naloge smo najprej predstavili poplave, njihove značilnosti, lastnosti poplav v Sloveniji ter varstvo pred poplavami. V nadaljevanju naloge so predstavljene hidrogeološke, hidrografske ter meteorološke značilnosti porečja Save. Nato so opisane vodomerne postaje ter izbira vodomernih postaj za analizo. Nadaljnje smo predstavili program Hidrolog, s katerim smo pridobili iskane hidrološke podatke. Pridobljeni hidrološki podatki so podatki o datumih konic ter podatki o pretokih na posameznih obravnavanih vodomernih postajah. S hidrološkimi podatki smo grafično in tabelarično prikazali potovanje visokovodnih konic po reki Savi in njenih glavnih pritokih. Izračunani so bili povprečni časi potovanja visokovodnih konic na reki Savi. Pri izračunu časa potovanja visokovodnih konic smo prišli do naslednjih ugotovitev. Čas potovanja se z oddaljenostjo od vodomernih postaj dolvodno po reki Savi povečuje. Pri vodomerni postaji Medno je pri izračunu prišlo do negativne vrednosti časa, kar je posledica vpliva hidroelektrarne Medvode. Izračunali smo, da povprečni visokovodni val Save potuje od Jesenic do Radovljice 3, 7 ure, do Šentjakoba 9,2 ure, do Litije 15,1 ur, do Hrastnika 17,4 ur in do Čateža 23,5 ur. In this diploma work the analysis of flood waves along the Sava river is discussed. In the introductory part of the thesis floods are presented, and also their characteristics, characteristics of floods in Slovenia and flood protection measures. In the following part hydrogeological, hydrographical and meteorological characteristisc of the Sava river basin are presented. Then the water gauging stations are described and our choice of water gauging stations for the analysis is depicted. Further, a program Hidrolog is presented which helped us to get hydrological data needed. Acquired hydrological data are data of dates of flood peak discharges and data of discharges at individual water gauging stations. These hydrological data were required to show travelling of flood peak discharges on the Sava river and its main tributaries in graphical and tabular form. In the diploma work the average times of flood peak discharges on the Sava river were calculated and the following conclusions were reached. Time traveling is increasing with the distance of water gauging stations downstream the Sava river. At water gauging station Medno there was a negative value, the reason is Hydroelectric Power Station Medvode. We found out, that the average flood wave of the Sava river travel from Jesenice to Radovljica 3,7 h, to Šentjakob 9,2 h, to Litija 15,1 h, to Hrastnik 17,4 h and to Čatež 23,5 h.

Vse pogosteje smo priča izrednim hidrološkim dogodkom, ki so posledica različnih slučajnih naravnih pojavov. Na slučajne mehanizme narave, ki takšne dogodke sprožijo, ne moremo vplivati, lahko pa se nanje delno pripravimo z analiziranjem preteklih dogodkov. Takšen dogodek predstavljajo tudi poplave. Poznavanje pojava visokih voda nam omogoča učinkovitejše varstvo pred poplavami, ustreznejše načrtovanje rabe prostora ter na splošno boljše gospodarjenje z vodami. Z verjetnostno analizo visokovodnih valov pridobimo informacijo o povezavi med vrednostjo pretoka in njegovo povratno dobo. Določeni poplavni dogodki pa so posledica več sočasnih slučajnih dogodkov. Poplavljanje pritoka pred sotočjem je lahko posledica povečanega pretoka samega pritoka ter sočasnega povečanega pretoka glavnega vodotoka na sotočju, ki povzroči zajezitev pritoka. V primeru, ko meritev pretoka pritoka pred sotočjem nimamo na voljo, lahko verjetnostno porazdelitev gladin pritoka pred sotočjem izračunamo na podlagi meritev pretoka pritoka gorvodno ter meritev pretoka glavnega vodotoka na sotočju z uporabo koincidenčne verjetnostne analize. V diplomski nalogi smo za izračun koincidenčne verjetnostne analize uporabili program HEC-SSP. Izdelali smo koincidenčno verjetnostno analizo visokovodnih valov na sotočju rek Soče in Vipave, pri čemer smo izračunali verjetnostno porazdelitev gladin Vipave v Sovodnjah na osnovi podatkov o pretoku Vipave v Mirnu ter podatkov o pretoku Soče na sotočju. Na gladino Vipave na odseku od sotočja do naselja Miren ob visokih vodah močno vpliva povečan pretok Soče na sotočju, ki povzroča zajezitev in s tem poplavljanje Vipave. Za zmanjšanje verjetnosti poplavljanja Vipave na tem odseku bi bilo zato najprej potrebno urediti strugo reke Soče, tako da ta ob visokih vodah ne bi povzročala zajezitve Vipave v tolikšnem obsegu. Increasingly, we are witnessing extreme hydrological events caused by various random natural phenomena. We cannot influence the random nature of the mechanisms, which trigger such events, but we can be partially prepared on them by analyzing past events. Floods represent such an event. Knowing the phenomena of high water allows a more efficient flood protection, appropriate land-use planning and an overall better water management. Frequency analysis of flood waves provides information on the relation between the value of the discharge and its return period. Some flood events are the result of multiple concurrent random events. Flooding on a river tributary, for example, can be influenced by both – discharge on that tributary and backwater effects due to discharge on the main stream. Coincident frequency analysis is used to develop a probability distribution for flood phenomena having no observed record when that phenomena is influenced by other random phenomena with available data. In the thesis we implemented a coincidence frequency analysis using the HEC-SSP program. We made the coincident frequency analysis of flood waves at the confluence of the Soča and the Vipava river, whereby we assessed the probability distribution of water levels of the Vipava river in Sovodnje on the basis of discharge data of the Vipava river in Miren and discharge data of the Soča river at the confluence. The water level of the Vipava river in its lower reach near the confluence is highly influenced by increased discharge of the Soča river at the confluence, which causes the backwater of the Vipava river. In order to reduce the probability of flooding of the Vipava river in its lower reach near the confluence, the stream of the Soča river should be first regulated in such a way, that at high water it would not cause the backwater of the Vipava river in such an extent.

V zadnjih desetletjih se vse pogosteje soočamo s številnimi hidrološkimi problemi, ki predstavljajo velik izziv in preizkušnjo za človeštvo. Danes je potreba po orodjih, ki izvajajo kompleksnejše analize hidrološkega režima, izredno velika, saj se lahko le z ustreznim preučevanjem, predvidevanjem in napovedovanjem možnih ekstremnih dogodkov nanje delno pripravimo in učinkovito izvajamo ukrepe za zaščito. Poznavanje soodvisnosti pretok – trajanje – verjetnost omogoča kompleksnejšo verjetnostno analizo, ki celoviteje opredeli pojave in vplive različnih posegov na pojave. Verjetnostna analiza pretočnih volumnov vključuje klasično verjetnostno analizo pretokov znotraj vsakega niza z določenim trajanjem. Povprečni pretoki so najprej izračunani na podlagi različnih stalnih trajanj. Nato pa je za vsako trajanje izvedena verjetnostna analiza letnih maksimalnih (minimalnih) pretokov z izbrano teoretično porazdelitvijo. V diplomski nalogi smo s programom HEC-SSP izvedli verjetnostno analizo pretočnih volumnov na vodomernih postajah v Sloveniji. Na primeru vodomerne postaje Jesenice na reki Savi Dolinki je prikazan celoten potek tovrstne verjetnostne analize, katere rezultate smo v zadnjem delu naloge uporabili na primeru akumulacijskega bazena HE Moste. Poskušali smo prikazati, kako z zadrževanjem maksimalnih pretokov različnih trajanj vplivamo na zmanjšanje pretokov dolvodno od pregrade, ter določili potrebni zadrževalni volumen akumulacije pri danem maksimalnem pretočnem volumnu in ob upoštevanju obratovalnega instaliranega in doinstaliranega pretoka hidroelektrarne Moste. In recent decades we are increasingly facing with many hydrological problems that pose a great challenge and test for humanity. Today, there is a significant need for tools that perform complex analysis of the hydrological regime. On the possible extreme events can be partially prepared and we can effectively implement measures to protect only through adequate studying, predicting and forecasting them. Knowing the interdependence of flow – duration – frequency allows more complex frequency analysis, which comprehensively defines the occurrence and impact of different interventions on the phenomena. Volume frequency analysis involves classic frequency analysis of maximum (minimum) flow within each of a set of specified durations. Average flow rates are first calculated based on different fixed durations. Then, for each duration frequency analysis of maximum (minimum) flow is performed with selected theoretical distribution. In the thesis we performed volume frequency analysis with HEC – SSP software for gauging stations in Slovenia. The entire course of volume frequency analysis is shown for gauging station Jesenice on the river Sava Dolinka. The results were used for the case of the reservoir HPP Moste, where we tried to show how the containment of flood flows with different durations influence on reducing the flow downstream of the barrier. We also determined the necessary containment volume of the reservoir for a given maximum inflow volume and the operational installed flow of the HPP Moste.

Poplave so naraven in izredno dinamičen pojav. V Sloveniji se pojavljajo kot posledica intenzivnih padavin in taljenja snega ali kombinacije obojega. Za učinkovito zaščito pred poplavami je zelo pomembna kvalitetna in zanesljiva izvedba verjetnostnih analiz, saj poplave povzročajo ogromno škodo in lahko ogrožajo tudi človeška življenja. V nalogi so verjetnostne analize visokih vod narejene na vzorcih letnih maksimumov. Metoda letnih maksimumov se v praksi uporablja najpogosteje. Predstavljene so različne teoretične porazdelitve in metoda momentov L za oceno njihovih parametrov. Opisanih je tudi nekaj statističnih testov, ki se uporabljajo za določitev najustreznejše porazdelitve. Predstavljen je tudi statistični Mann-Kendallov test za ugotavljanje trendov. V praktičnem delu naloge so za vodomerne postaje Slovenije narejene verjetnostne analize visokovodnih konic za različna 30-letna obdobja meritev. Pri verjetnostnih analizah je uporabljenih šest najpogosteje uporabljenih porazdelitvenih funkcij in narejena ocena parametrov po metodi momentov L. Z uporabo različnih testov smo za vsako postajo in obdobje izbrali porazdelitev, ki se najbolj prilega merjenim podatkom. Primerjali smo projektne pretoke izbranih povratnih dob med obdobjema 1961-1990 in 1981-2010 ter ugotovili, da lahko izbrano obdobje meritev pomembno vpliva na rezultate verjetnostnih analiz oz. da ima spremenljivost podnebja pomemben vpliv tudi na projektne pretoke večine vodomernih postaj v Sloveniji. Floods are a natural and a very dynamic phenomena. In Slovenia they may occur due to intense rainfall, snowmelt or a combination of both. Quality and reliable flood frequency analyses are necessary for effective flood protection, as floods caused extensive damage and can also threaten human lives. In the thesis flood frequency analyses were carried out with annual maximum series method which is most often used in practice. Different theoretical distributions are presented and the method of Lmoments for parameters estimation. Some statistical tests used to determine the most appropriate distribution are described. A statistical Mann-Kendall test for determing trends is also presented. In the practical part of the thesis flood frequency analyses for different 30-year periods of measurements for gauging station Slovenia are made. Six most commonly used distribution functions were used and parameters were estimated with the method of L-moments. Different tests were used to select the best fitting distribution for each measuring period and station. We compared the design flow of the selected return periods between the periods 1961-1990 and 1981-2010 and found that the selected measurement period has a significant impact on the results of the flood frequency analyses or in other words that climate variability has a significant impact on the design flow of the majority of gauging stations in Slovenia.

Namen diplomske naloge je predstavitev programa SWAT in njegovih s hidrologijo povezanih komponent ter analiza možnosti uporabe modulov programa, ki se nanašajo na fizikalne pojave gibanja vode pri oblikovanju površinskega odtoka. V praktičnem delu naloge je predstavljena uporaba programa na porečju Glinščice. V nalogi je predstavljen program SWAT, delujoč v programskem okolju MapWindow. V prvem delu naloge, so opisane teoretične osnove, ter pri izračunih uporabljene empirične enačbe in metode. Predstavljeno je prispevno območje ljubljanske Glinščice in priprava potrebnih vhodnih podatkov za model. Opisana je praktična uporaba programa, način delovanja in postopek izdelave modela padavinskega odtoka za izbrano prispevno območje. Nadalje je na kratko predstavljen program SWAT - CUP4 namenjen umerjanju in analizam občutljivosti. Sledijo rezultati umerjanja, analiza občutljivosti in validacije. Padavinske izgube so bile izračunane po metodah SCS ter Greena in Ampta. Model je bil umerjen na osnovi izmerjenih padavinskih dogodkov in pretokov treh mesecev. Postopek umerjanja modela je bil izveden s programom SWAT-CUP4. Vsako umerjanje, je bilo izvedeno z vsaj 4 iteracijami, znotraj katerih so opravljene simulacije različnih kombinacij parametrov. Rezultati so statistično ovrednoteni s kazalcema ujemanja P vrednostjo in R vrednostjo ter Nash - Sutcliffe koeficientom in koeficientom determinacije. The purpose of the diploma thesis is to present SWAT program, its hydrological components and feasibility of using program modules relating the physical processes of water movement and surface runoff. The practical part describes the application of the program on Glinščica watershed. The diploma thesis consists of the presentation of the program SWAT, based on the MapWindow platform. The theoretical basics of the program and the empirical equations and methods employed for calculations are listed in the first part. It also includes a detailed description of the Glinščica watershed and the input data preparation required by a model. Further, the application, functioning and procedure of modelling rainfall - runoff for the Glinščica watershed are presented. There is also a short presentation of the SWAT - CUP4 program, intended for calibration and sensitivity analysis, followed by the calibration results, sensitivity analysis and validation results. Surface runoff was computed using SCS Curve Number and Green and Ampt loss method procedure. The model was calibrated on the basis of the measured hydrographs and runoff volumes on Glinščica watershed for rainfall events and water flow rate in three month period. The calibration procedure has been carried out by the SWAT-CUP4 program. Each calibration of the SWAT run consists of at least four iterations, in which the simulations of different parameter combinations have been executed. Statistical analyses are presented with the R - factor and P - factor, which shows the goodness of fit and Nash - Sutcliffe coefficient and coefficient of determination.

Znano je, da imata obseg in vrsta vegetacije vpliv na stanje vodne bilance porečja. S procesom prestrezanja padavin, vegetacija uravnava procese kot sta evapotranspiracija in odtok. Mnoge raziskave kažejo na znatno povečanje odtoka, pretoka in vodnih zalog po sečnji gozdov. To lahko razložimo z manjšo stopnjo izhlapevanja na porečjih, kjer prevladuje trava z nizkim rastlinjem v primerjavi s tistimi, ki so porasla z gozdovi. V želji po boljšem poznavanju odnosa med spremembami vegetacijskega pokrova in vodnimi zalogami je bil razvit Zhangov model. Zhangov model smo v praktičnem delu diplomskega dela preizkusili na 125 hidrometričnih zaledjih na območju Slovenije in z njim ocenili stopnjo evapotranspiracije in odtoka ter ju primerjali s podatki Agencije Republike Slovenije za okolje. V nadaljevanju naloge sta predstavljena prilagojena Zhangova modela, ki sta bila razvita v želji po zmanjšanju odstopanj od merjenih podatkov. Originalni Zhangov model smo prilagodili z uvedbo novih konstant in dopolnili na podlagi ugotovljenih odnosov med letno količino padavin in odstopanji modela. Ob koncu smo prilagojeni model uporabili za ocenjevanje vpliva spremembe vegetacijskega pokrova na vodno bilanco izbranega porečja. It is a well known fact that amount and type of catchment vegetation will affect its water balance. Through process of precipitation interception, vegetation coverage plays an important role in regulating processes as evapotranspiration and runoff. Many studies have shown significant increase of water surface runoff, discharge and water yield after forest cover was removed. A clear conclusion can be drawn from this: grassed catchments decrease catchment evapotranspiration, while the opposite stands for forested ones. To help determine the exact relations between vegetation cover changes and water yield Zhang's model was developed. In this graduation thesis Zhang model was put to the test to assess evapotranspiration and runoff of 125 hydrometric catchment areas in Slovenia and results were compared against national meteorological agency data. Following, two additional extensions of Zhang model were developed to decrease deviations of model from measured data: first one based on determination of new constants, and second one on relationship between annual amount of precipitation and deviations of the model. In the final part of this work, adapted model is used to assess impact of vegetation cover changes on catchment water balance of hydrometric catchment area of choice.

V diplomski nalogi so predstavljene tri izbrane metode merjenja in izračuna evapotranspiracije na raziskovalni ploskvi na Hajdrihovi 28 in sicer merjenje z evaporacijsko posodo A ter izračun potencialne evapotranspiracije z dvema empiričnima enačbama: FAO Penman-Monteithovo enačbo in Thornthwaitovo enačbo. Dobljene rezultate vseh treh metod smo med seboj primerjali, izračunane vrednosti po FAO Penman-Monteithovi enačbi pa smo primerjali tudi z izračuni na ARSO-vi meteorološki postaji Ljubljana-Bežigrad. Rezultati so pokazali, da so med metodami precejšnje razlike. Najmanjše vrednosti smo dobili z meritvami z evaporacijsko posodo, nekoliko višje po enostavni Thornthwaitovi enačbi, najvišje pa po FAO Penman-Monteithovi enačbi. Analiza vplivnih dejavnikov je pokazala, da je na raziskovalni ploskvi najvplivnejši dejavnik na evapotranspiracijo sončno sevanje, sledi mu relativna vlažnost, nekoliko manjši vpliv pa imata temperatura in veter. The thesis presents three selected methods of measurement and calculation of the evapotranspiration on research plot at Hajdrihova 28 in Ljubljana. First method is measurement by evaporation pan type A and the other two methods are empirical equations for potential evapotranspiration calculation: FAO Penman-Monteith equation and Thornthwait equation. The results obtained for all three methods are compared with each other. Calculated results according to the FAO Penman-Monteith equation were compared also to those from Slovenian Environment Agency meteorological station Ljubljana-Bežigrad. The results showed considerable differences between methods. The lowest values were obtained with the measurement by evaporation station type A, slightly higher values were calculated by simple Thornthwait equation and the highest by FAO Penman-Monteith equation. Analysis of the influential factors showed that on the research plot the most influential factor is solar radiation, followed by relative humidity. Lower impact is shown by air temperature and wind speed.

Sneg je v hidrološkem krogu zelo pomemben dejavnik, saj se v njem zadržuje velik del vode. Hitro taljenje snežne odeje lahko povzroči poplave, pomanjkanje snega v nekaterih porečjih pa lahko vodi v poletne suše. V diplomski nalogi smo primerjali programa HEC-HMS (verzija 3.5) in SRM (verzija 1.12), s pomočjo katerih smo modelirali odtok zaradi taljenja snežne odeje s porečja Sava-Kranjska Gora. V prvem delu naloge je opisana energijska bilanca snežne odeje, fizikalni procesi, ki so vključeni v nalaganju, preobrazbi in taljenju snega ter osnovne enačbe, ki te procese opisujejo. Na nastanek snežnih padavin vplivajo razmere v oblakih, na porazdelitev in višino snežne odeje pa dejavniki kot so: veter, vegetacija, temperatura zraka, sončno sevanje, padavine in kondukcija toplote iz zemljišča. Pri računanju taljenja snega moramo biti pozorni tudi na gostoto, temperaturo in albedo snežne odeje. Za določitev količine staljene vode je ključno poznavanje snežnega vodnega ekvivalenta (SVE), ki nam poda količino vode, ki bi jo dobili, če bi se vzorec snega v celoti stalil. Za napovedovanje pretokov in računanje taljenja snega se uporabljata dva osnovna pristopa: podatkovno obsežnejša metoda energijske bilance in metoda temperaturnega indeksa, ki je preprostejša za uporabo, vendar manj natančna. Oba programa, HEC-HMS in SRM, delujeta na principu temperaturnega indeksa. V nadaljevanju so predstavljene naravno-geografske in hidrološke značilnosti prispevnega območja porečja Sava-Kranjska Gora in priprava potrebnih vhodnih podatkov za oba modela. Modela sta bila umerjena na osnovi izmerjenih padavinskih dogodkov in pretokov dveh mesecev. Sledijo rezultati umerjanja, analiza občutljivosti in primerjava rezultatov obeh modelov. Snow is a very important factor in the hydrological cycle, since it retains a large part of water. Rapid snowmelt can cause flooding, while on the other hand, the lack of snow in some river basins can lead to summer draught. Therefore the comparison of two snowmelt models HEC-HMS (version 3.5) and SRM (version 1.12) for the Sava-Kranjska Gora basin has been made in this thesis. In the first part of the thesis we described energy budget of snow cover, physical processes involved in snow accumulation, metamorphosis and melt, and fundamental equations that describe these processes. The formation of snow is affected by the conditions in clouds the distribution and amount of snow depends on factors such as wind, vegetation, air temperature, solar radiation, precipitation and heat conduction from the ground. Snowmelt, density, temperature and snow albedo have to be considered by computing. For the determination of the melted water knowledge of snow water equivalent (SWE) is required. SWE gives us the amount of water that would be obtained if the sample of snow is fully melted. Basic approaches for streamflow forecasting and computing snowmelt are: extensive data energy budget method and temperature index method which is simpler to use, but less accurate. Both models, HEC-HMS and SRM, calculate snowmelt with the temperature index approach. Further, the physical geographical and hydrological characteristics of the drainage basin of the Sava-Kranjska Gora and preparation of the necessary input data for both models are presented. The models were calibrated based on measured precipitation events and runoff of two months. The thesis also contains the results of the calibration, the sensitivity analysis and the comparison of models.

Namen naloge je predstaviti orodje R, teoretično podlago hidrološkega modeliranja in samega hidrološkega modeliranje v programu R. Program R je prosto dostopen, zato je njegova uporaba zelo razširjena. V osnovi je namenjen statističnim in matematičnim izračunom, vendar s pomočjo nekaterih razširitev, imenovanih paketi, lahko postane sposobno orodje tudi za hidrološko modeliranje. Zaradi odprtokodnosti in široke uporabe, je na voljo ogromno paketov, ki omogočajo raznovrstno uporabo tudi v drugih strokah. Naloga je sestavljena iz več sklopov, ki predstavijo hidrološko modeliranje, teoretično osnovo treh različnih hidroloških modelov ter pomen in teoretično osnovo kriterijev učinkovitosti. V praktičnem delu naloge je prikazan postopek izdelave hidroloških modelov v programu R za porečje Glinščice, predstavitev ter analiza rezultatov. Za boljše razumevanje rezultatov in poznavanja posameznega hidrološkega modela je v nalogi predstavljena tudi kratka analiza občutljivosti posameznega modela ter ocena modela z osmimi različnimi kriteriji, ločeno za obdobje umerjanja ter obdobje validacije. The goal of this thesis is to introduce R as a software tool, the basic theory behind hydrological modelling and hydrological modelling in R itself. The software is freely available, therefore its user base is very wide. In its basic form it is used for statistical and mathematical computing, but with a help of a few add-ons, called packages, it can be a capable tool for hydrological modelling. Because of its open-source nature and wide user base, there are many add-ons available, which enabled its multi-professional usage. The thesis is devised of plural chapters, which introduce the concept of hydrological modelling, theoretical basis of three different hydrological models and the meaning and theory behind criteria of efficency. In the practical part the procedure of creating hydrological models by using R software for Glinščica river basin and analysis of the results are presented. For better understanding of the results and individual hydrological model the thesis includes also short sensitivity analysis and evaluation with eight different efficiency criteria separetly for calibration and validation period.