1,721,101 research outputs found
Sediment transport modelling in the Sava Dolinka River
No full textV okviru magistrske naloge je obravnavana tematika modeliranja transporta (rinjenih) plavin. Predstavljene so teoretične osnove, potrebne za celovito obravnavo, pod kar spadajo tako določitev dotoka plavin iz zaledja, kot tudi lastnosti premeščanja plavin znotraj struge vodotoka. Pri prvi so predstavljene metode določitve potencialnega sproščanja sedimentov v zaledjih, pri drugi pa osnove o začetku prodnega premika, lastnostih različnih tipov premeščanja plavin in o različnih metodah določitve transportne zmogljivosti oz. količine premeščanja plavin v vodotoku. Premeščanje plavin je v nalogi obravnavano na konkretnem primeru Save Dolinke, ki predstavlja tipičen prodonosni vodotok. Obravnavan je bil odsek med sotočjem s Pišnico (Kranjska Gora) in prodnim zadrževalnikom Hrušica. Za omenjeni odsek je bil vzpostavljen enodimenzijski hidravlični model, dodatno prilagojen za modeliranje transporta sedimentov. Z njegovo uporabo je bila analizirana dinamika premeščanja rinjenih plavin na obravnavanem odseku. Dodatno je bil ocenjen vpliv lastnosti vodotoka (vodnatost, hrapavost podlage in zrnavost podlage), kot tudi nastavitev hidravličnega modela (izbira transportne funkcije itd.) na rezultate modeliranja transporta plavin. V zaključkih so na podlagi ugotovljenega vpliva posameznih parametrov podane smernice, ki določajo, čemu je pri modeliranju transporta potrebno posvetiti največ pozornosti, da bi zagotovili čim manjšo negotovost rezultatov. Predstavljene so prednosti in slabosti uporabljene metode modeliranja, ugotovljene tekom izdelave magistrske naloge. Na podlagi tega je bila posledično ocenjena njena uporabnost v različnih primerih.Within the Master\u27s thesis, we discuss the topic of modelling the transport of bedload sediments. We present the theoretical bases, which includes determination of sediment inflow from the hinterland, as well as the characteristics of sediment transport within the watercourse bed. Determination of sediment inflow wise, we describe the methods for determination of potential erosion of sediments in the hinterland. In the case of sediment transport within the riverbed, we introduce the basics of the start of bed load transport, the characteristics of different types of sediment transport as well as different methods of determining the transport capacity and the amount of sediment transport in the watercourse. In the thesis, the bed load transport is discussed on the concrete example of the Sava Dolinka river, which represents a typical gravel bed river. We focused on the section between the confluence with Pišnica (Kranjska Gora) and the dam Hrušica. A one-dimensional hydraulic model was established for the aforementioned section, additionally adapted for sediment transport modelling. It was used to analyse the dynamics of the bedload transport in this section. In addition, we evaluate the influence of watercourse qualities (water amount, roughness and grain size distribution), as well as hydraulic model settings (choice of transport function, etc.) on bed load transport modelling results. In the end, based on the established impact of individual parameters, we provide guidelines that highlight the priorities that should be given the most attention in bed load transport modelling in order to ensure the low uncertainty of the modelling results. The advantages and disadvantages of the applied modelling methods, established during the preparation of the Master\u27s thesis, are presented. Based on this, their usefulness in various cases was assessed
Use of a stohastic precipitation model for determing design discharges in savinja river basin
No full textZ vse bolj izrazitim spreminjanjem našega okolja kot posledica podnebnih sprememb, so tudi ekstremni vremenski pojavi vse pogostejši. Temu smo bili priča tudi v letu 2023, ko je obilno deževje povzročilo poplave, ki jih v novejši zgodovini Slovenije ne pomnimo. Te so povzročile ogromno škodo na infrastrukturi, gospodarstvu, lastnini ter duševnemu zdravju prebivalcev.
V nalogi smo spoznali enega izmed načinov, ki nam omogočajo predvidevanje oziroma računsko določanje tovrstnih ekstremnih dogodkov oziroma določanje projektnih pretokov. Obravnavali smo prispevno območje vodomerne postaje Nazarje, ki se nahaja v Zgornje Savinjski dolini na reki Savinji. Na podlagi podatkov pridobljenih s strani Agencije RS za okolje, smo v programskem orodju R, vzpostavili stohastični padavinski model za generiranje sintetičnih padavin in temperature zraka. Znotraj istega programskega orodja smo vzpostavili tudi hidrološki model padavine-odtok, s pomočjo katerega smo lahko na podlagi izračunanih sintetičnih padavin in temperature zraka ter verjetnostne analize določili projektne pretoke na obravnavanem območju.
Analiza generiranih podatkov za različna časovna obdobja z uporabo stohastičnega padavinskega modela je pokazala, da se scenariji in izračunane vrednosti lahko spreminjajo pri vsakem ponovnem zagonu modela, tudi če število scenarijev ostaja ne spremenjeno. To nakazuje potrebo po večkratnem ponavljanju izračunov z več scenariji za natančnejše rezultate. Nadaljnje analize so pokazale, da se projektni pretoki različnih povratnih dob ne spreminjajo, če se število scenarijev povečuje ob ohranjanju istega časovnega obdobja, temveč se ti zgolj dopolnijo z rezultati novih oziroma dodanih scenarijev.
Primerjava med merjenimi in generiranimi podatki je pokazala podobnosti v oblikah verjetnostnih krivulj projektnih pretokov, čeprav so bile razlike večje pri povratnih dobah nad 100 let. Na odstopanje med rezultati vpliva tudi uporaba dnevnih vrednostih. Za boljše delovanje modela bi bilo potrebno uporabljati urne časovne podatke in natančnejše podatke o temperaturi zraka.With the increasing changes in our environment due to climate change, extreme weather events are also becoming more frequent. We witnessed this in 2023 when heavy rainfall caused floods unprecedented in the history of Slovenia. These floods caused extensive damage to infrastructure, the economy, property, and the mental health of residents.
In this thesis, we explored one of several methods that allow us to predict or computationally determine such extreme events and design discharge values. We examined the catchment area of the Nazarje gauging station, located in the Upper Savinja Valley on the Savinja River. Based on the data obtained from the Slovenian Environmental Agency (ARSO), we established a stochastic precipitation model in the R software for generating synthetic precipitation and air temperature data. Within the same software, we also established a rainfall-runoff hydrological model, which enabled us to determine design discharge values in the studied area based on the calculated synthetic precipitation and air temperature data, and flood frequency analysis.
The analysis of generated data for different time periods using the stochastic model revealed that scenarios and calculated values can vary with each simulation of the model, even if the number of scenarios remains unchanged. This indicates the need for repeated calculations with more scenarios for more robust results. Further analyses showed that design discharge values for different return periods do not change if the number of scenarios increases while maintaining the same length of simulations, but rather are supplemented with results from new or additional scenarios. Comparison between measured and generated data showed similarities in the shapes of design discahrge curves, although differences were more significant for return periods over 100 years. For better model performance, it would be necessary to use hourly time step and more precise air temperature data, which we could not provide due to the sparse network of measuring stations
Determination of grain size distribution of river sediments on natural gravel bars
No full textPremeščanje plavin je eden izmed pomembnejših procesov v vodotokih. Drobnejša, lažja zrna se pogosteje premeščajo z vodnim tokom, med tem ko se večja in težja zrna premeščajo samo ob večjih pretokih oz. ob večjih poplavnih dogodkih. Pomembno je, da poznamo podatek o zrnavostni sestavi, saj se le ta uporablja pri izračunih premestitvene zmogljivosti. Podatek je pomemben tudi z vidika ocene hrapavosti dna. Plavine v rečnem dnu so sestavljene iz dveh plasti, iz vrhnjega krovnega sloja ali posteljice dna in iz spodnje podlage. Pomembno je, da se analize zrnavosti plavin lotevamo ločeno za obe plasti posebej, saj se za različne analize uporabljajo različna značilna zrna. Pri oceni hrapavosti se uporablja podatek o zrnavosti krovnega sloja, za izračun prodnega premika pa se uporablja reprezentativno zrno podlage. V okviru diplomske naloge smo določali zrnavostno sestavo petih naravnih prodišč na območju srednje Save. Za vsako lokacijo smo uporabili 3 različne metode in na koncu primerjali dobljene rezultate. Zrnavost smo določali s sejalno analizo, linijsko analizo in optično analizo s pomočjo programa Basegrain. Rezultat vsake analize je bila zrnavostna krivulja, s pomočjo katere smo določili karakteristična zrna, d10, d30, d50, d70, d90 in srednje aritmetično zrno dm. Z izbranimi statističnimi testi smo primerjali vrednosti značilnih zrn. Rezultati uporabljenih statističnih testov za vse metode podajo podobne rezultate, vendar so določeni rezultati bolj podobni od drugih. Največkrat so najbolj primerljivi rezultati linijskih in optičnih analiz, rezultati sejalne in linijske analize pa pogosto najbolj odstopajo od ostalih. To je tudi pričakovano, saj se pri različnih metodah analizira drugačne vzorce. Pri sejalni metodi smo vzorčili ploskovni krovni sloj plavin, medtem ko pri linijski in optični analizi podatke preračunamo v prostorninski vzorec, ki predstavlja tudi podatek o zrnavosti podlage in ne samo krovnega sloja. Ugotovili smo tudi, da zrnavost ni enaka niti znotraj posameznega prodišča, ampak se spreminja ob spremenljivih pretočnih razmerah in je odvisna od mikrolokacije na prodišču. Ker je podatek o zrnavostni sestavi precej pomemben, bi lahko z majhnim finančnim in časovnim vložkom v nekem časovnem intervalu izvajali meritve na določenih lokacijah, s čimer bi pridobili podatke o spreminjanju zrnavostne sestave skozi čas. S tem informacijam bi lahko bolje razumeli in predvidevali dogajanje v vodotokih. Glede na rezultate te diplomske naloge priporočamo določanje zrnavostne sestave s kombinacijo izvedbe linijske in optične analize, saj podajata primerljive rezultate, sta obe časovno relativno hitri, poceni in ne zahtevata posebnega dostopa do lokacije, kot npr. sejalna analiza.The sediment transport is one of the most important processes in watercourses. Smaller, lighter grains are transported more often by the water flow, while larger and heavier grains are transported only during larger flows or during major flooding events. It is important to know the information about the grain size distribution, because is used in the sediment capacity calculations. It is also essential for the assessment of channel roughness. River bed consists of two layers. It is important that the analysis of sediment grain size is undertaken separately for both layers since different characteristic grains are used for different analyses. Data on the grain size of the top layer is used to estimate the roughness, and a representative grain of the base is used to calculate the sediment transport. As part of the diploma thesis, we determined the grain size distribution of five natural gravel bars in the area of the middle Sava. We used 3 different methods for each location and finally we compared the results obtained. Grain size was determined by sieving analysis, line analysis and optical analysis using the Basegrain software. The result of each analysis was a grain size curve, with the help of which we determined the characteristic grains, d10, d30, d50, d70, d90 and the mean arithmetic grain dm. The values of characteristic grains were compared with selected statistical tests. The results of the statistical tests used for all methods give similar results, but certain results are more comparable than others. In most cases, the results of line and optical analyses are the most comparable, while the results of sieving and line analysis often deviate the most. This is also expected, since different samples are analyzed with different methods. In the sieving method, only the upper covering layer of the sediments was sampled, while in linear and optical analysis, the data is converted into a volumetric sample, which also represents data on the grain size of the base and not only the top layer. We also found that the grain size is not the same even within an individual gravel bar but changes all the time with changing flow conditions and depends on the micro location. Since the data on the granular distribution is quite important, with a small financial and time investment, measurements could be carried out at certain locations at certain time intervals, thereby obtaining data on changes in the granular distribution over time. With this information, we could better understand and predict what is happening in watercourses. Based on the results of this thesis, we recommend determining the grain size distribution by a combination of linear and optical analysis, as they provide comparable results, both are relatively quick, cheap and do not require special access to the location, such as e.g., sieving analysis
Analysis of hybrid infrastructure on floods
No full textTrenutni načini gradnje in izrazito povečevanje urbanizacije prispevajo k velikemu deležu neprepustnih površin. Takšne površine zmanjšujejo infiltracijo padavin v tla, kar posledično vodi k velikim površinskim odtokom, ki imajo lahko negativne posledice. Z vpeljavo zelene in hibridne infrastrukture poskušamo izboljšati značilnosti urbanih površin z vidika povečanja infiltracije padavinske vode. V teoretičnem delu so predstavljeni in opisani osnovni pojmi, ki so potrebni za razumevanje površinskega odtoka. Poleg tega so predstavljeni in opisani različni tipi zelene in hibridne infrastrukture, s katerimi poskušamo zmanjšati negativne posledice povečanega površinskega odtoka. V nalogi smo obravnavali večje industrijsko območje Rudnik v Ljubljani. Za območje smo določili koeficient hidravlične prevodnosti s pomočjo terenskih meritev z infiltrometrom. Poleg tega smo analizirali merjene padavinske podatke za obdobje 1982–2022 in izračunane modelske rezultate pričakovanih podnebnih sprememb za preteklo obdobje (1981–2020), obdobje bližnje prihodnosti (2021–2060) in obdobje daljne prihodnosti (2061–2100). Podatke o koeficientih infiltracije in padavinah smo uporabili kot vhodne podatke v spletnem orodju Green ValuesTM Calculator. S pomočjo spletnega orodja smo ugotavljali vplive implementacije različnih tipov zelene in hibridne infrastrukture na površinski odtok. Poleg tega smo izdelali ekonomsko analizo stroškov in koristi različnih zelenih in hibridnih infrastruktur. Na podlagi analize podatkov, meritev in izračunov smo ugotovili, da hibridna in zelena infrastruktura pozitivno prispevata k zmanjšanju površinskega odtoka na urbanih površinah. Z vidika površinskega odtoka je bila kot najboljša rešitev ugotovljena uporaba poroznih talnih površin, z finančnega vidika pa so bila kot najboljša rešitev ugotovljena drevesa.Current construction methods and increase in urbanisation contributes to the increase in percentage of impermeable surfaces. Such surfaces limit the infiltration of rainfall into the ground, which in turn leads to high surface runoff with potentially negative characteristics. By introducing green and hybrid infrastructure measures, we aim to improve the characteristics of urban areas in term of rainwater infiltration and reducing surface runoff. The theoretical part introduces and describes the basic concepts needed to understand surface runoff formation. In addition, different types of green and hybrid infrastructure are presented and described since these measures present an attempt to reduce the negative effects of surface runoff. In this thesis, we are dealing with a large industrial area in the city of Ljubljana. The saturated hydraulic conductivity coefficient for the area was calculated using field measurements with a mini-disk infiltrometer. In addition, we analysed measured precipitation data for the period 1982-2022, and calculated model data (downscalled and bias-corrected climate change predictions) for the past period (1981-2020), near future period (2021-2060) and the far future period (2061-2100). Infiltration coefficient and precipitation data were used as inputs in online tool Green ValuesTM Calculator. We used web-based tool to identify the impacts of implementing different types of green and hybrid infrastructure. Beside that we have carried out an economic analysis of the costs and benefits of different green and hybrid infrastructures. Based on the analysis of data, measurements and calculations, we found that hybrid and green infrastructure contribute positively to reducing surface runoff in urban areas. In terms of surface runoff, the use of porous ground surfaces was identified as the best solution, while trees were identified as the best solution from a financial point of view
Measurements of suspended sediments in the catchment area of the Kamniška Bistrica river
No full textErozija ter posledično transport rečnih sedimentov, je pomemben in stalno prisoten proces v vseh vodotokih. S transportom materiala je povezano nenehno spreminjanje in preoblikovanje same rečne struge ter njene okolice. Zaradi tega je spremljanje in poznavanje omenjenih procesov ključno za razumevanje in trajnostno upravljanje vodotokov. V okviru diplomske naloge sem obravnaval rečni transport sedimentov, najbolj pa sem se posvetil rinjenim in lebdečim plavinam. Konkretne meritve in izračune sem izvajal na vodotokih Kamniška Bistrica in Pšata.Erosion and consequently the transport of river sediments is an important and constantly present process in all watercourses. The transport of material is associated with the constant change and transformation of the river bed itself and its surroundings. Therefore, monitoring and knowledge of these processes are crucial for understanding and sustainable management of watercourses. As part of my thesis, I dealt with river transport of sediments, focusing mainly on bed load and suspended load. I have been performing measurements and calculations for these two types of sediments on the Kamniška Bistrica and Pšata watercourses. The main goal of my thesis was, in the scope of the computational part, to determine the impact of precipitation and water flows on the content of suspended solids in the river flow. As a result, I wanted to derive the equation, to connect the river flows with the amounts of suspended solids. So in the future, only by using these two formulas, each of the considered watercourses needs its own, we could estimate the suspended solids for these considered watercourses. Only river flow values would be needed as input. I also correlated the amount of daily precipitation and suspended solids in the same way, but it turned out to be less appropriate. Estimated suspended solid based on the derived equations should be regarded as rough approximation of the actual state in the rivers while continus measurements are needed to enhance these estimates. Bed load transport at the selected locations in the Kamniška Bistrica river was also evaluated
Uporaba produktov reanaliz za namen hidrološkega modeliranja: izbrani primeri v Sloveniji
No full textHidrološko modeliranje nemerjenih porečij je še vedno velik izziv, saj za taka porečja ni na voljo ali podatkov o pretokih ali podatkov o padavanih in temperaturi zraka. V zadnjih letih je bilo na tem področju narejenih veliko raziskav. Ena izmed metod, ki jih lahko uporabimo namesto točkovno merjenih podatkov, so podatki reanaliz, ki združujejo modelske izračune, točkovne meritve ter tudi satelitske in radarske podatke.
Magistrska naloga analizira ustreznost dveh produktov reanaliz z vidika ustreznosti podatkov opadavinah in temperaturi zraka. Izbrana sta dva produkta, in sicer ERA5 in COSMO-REA6,ki sta v nalogi testirana na izbranih porečjih na območju Slovenije. Oba produkta imata na voljopodatke z urnim časovnim korakom in do sedaj z vidika hidrološkega modeliranja površinskegaodtoka še nista bila preverjena. Za modeliranje sta uporabljena enovita konceptualna modelaGR4H in CemaNeigeGR4H. Testirane so različne konfiguracije modelov (npr. s ponovnimumerjanjem ali brez le-tega).
Ugotovljeno je bilo, da so podatki reanaliz primerni za uporabo samo za nekatera porečja, in sicer v primeru da hidrološki model ni ponovno umerjen na podatke reanaliz, ampak se privzame parametre, določene glede na točkovno izmerjene podatke. Ponovno umerjanje modela pa je izboljšalo rezultate modeliranja. Rezultati so pokazali, da se izbrana produkta reanaliz delno ujemata s točkovno izmerjenimi podatki, kar pomeni da ju lahko upoorabimo kot grobo oceno dejanskega stanja v primeru, da podatkov o padavinah in temperaturi zraka ni na razpolago.The need for hydrological modeling in ungauged basins has always been a major challenge. Efforts have been made in recent years to address it via the implementation of ex-situ technologies. An attractive option that is becoming increasingly popular are reanalysis products, which provide modeled data for atmospheric variables, based on observations assimilated from various sources, such as satellites and radar stations. The present study is focusing on the evaluation of two reanalysis precipitation and temperature datasets, namely ERA5 and COSMO-REA6, over a selection of drainage basins located in Slovenia. The two products are available at the hourly temporal scale, and at the time of writing, their quality has not been evaluated in rainfall-runoff applications over European borders. To measure their efficiency, the GR4H and GR4H Cema Neige lumped conceptual rainfall-runoff models were used. Different reanalysis configurations were tested by using the initial model parameters, calibrated using observed data. In addition, it was investigated whether the parameters ingrained within the model are able to make up for low rainfall and temperature data quality, by recalibrating them on every reanalysis configuration. Initial model runs proved to be adequate only for a few catchments out of the total selection. However, the recalibration process was effective in increasing hydrological performance, increasing the total number of watersheds that were modeled accurately. The study concluded that the two products are partially in agreement with observations, suggesting their use as a proxy when observed data is scarce
Vrednotenje protipoplavnih ukrepov z upoštevanjem podnebnih sprememb
No full textFloods are estimated to be one of the most frequently occurring natural hazards in Europe, which brings significant damages and threats to human life. Different mitigating strategies are being implemented nowadays to cope with different flood events due to the unpredictability of each particular flood disaster. What is more, the frequency and magnitude of this devastating natural phenomenon is expected to increase over time, which makes it necessary to establish effective flood mitigation measures to deal with the severe hazard. This research was conducted in order to define the most effective and suitable flood mitigation facilities for the selected case study, which is the Glinščica River catchment, located within the Ljubljana municipality in Slovenia. In this study to achieve the main research objective the following grey, green and hybrid flood mitigation measures were chosen for further modelling based on the conducted literature review: sidewalks and drywells/cisterns (grey measures), urban trees and rain gardens (green measures), green roofs and stormwater tree trenches (hybrid measures). The hydrological modelling was performed in HEC-HMS software to analyze the performance of the selected flood mitigation measures and define the most feasible ones for the chosen case study. To accomplish this, synthetic rainfall events and climate change scenarios were used as precipitation data. The modelling procedure was based on the SCS Curve Number (CN) method, where the CNs for each subbasin and each particular scenario were chosen according to the SCS soil type and land use type maps. In addition, lag time parameters were also calculated for each case based on the defined CNs and characteristics of each subbasin. In this study rain gardens were found to be the most effective measure with respect to the reduction in peak discharge and outflow volume at the final point of the Glinščica River model. Both green roofs and stormwater cisterns 1 (volume~11.4 m3) also showed relatively good results compared to the remaining measures. Depending on the scenario (1-8), the last place was occupied by permeable sidewalks and stormwater cisterns 2 (volume~5.7 m3). The detailed modelling procedure and final outcomes of the research are presented throughout this study.Ocenjuje se, da so poplave ena najpogostejših naravnih nesreč v Evropi, ki povzroča znatno škodo in ogroža človeška življenja. Dandanes se zaradi nepredvidljivosti vsake posamezne poplave izvajajo različne strategije za zmanjšanje tveganja, da bi se spopadli z različnimi poplavnimi dogodki. Poleg tega se pričakuje, da se bosta pogostost in intenzivnost tpoplav povečala, zaradi česar je treba vzpostaviti učinkovite ukrepe za zmanjšanje poplavne škode. Raziskava je bila izvedena z namenom, da bi opredelili najučinkovitejše in najprimernejše ukrepe za ublažitev poplav za izbrano študijo primera, to je povodje reke Glinščice, ki se nahaja v občini Ljubljana v Sloveniji. V tej nalogi smo za dosego glavnega raziskovalnega cilja uporabili modeliranje na podlagi izvedenega pregleda literature izbranih sivih, zelenih in hibridnih ukrepov za ublažitev poplav. Upoštevali smo naslednje ukrepe: porozni pločniki in zadrževalniki vode/cisterne (sivi ukrepi), urbana drevesa in dežni vrtovi (zeleni ukrepi), zelene strehe in jarki za meteorne vode (hibridni ukrepi). Hidrološko modeliranje je bilo izvedeno v programski opremi HEC-HMS, da bi analizirali uspešnost izbranih ukrepov za zmanjšanje poplav in opredelili najbolj učinkovite ukrepe za izbrano študijo primera. Da bi to dosegli, smo kot vhodne podatke o padavinah uporabili sintetične dogodke padavin in scenarije podnebnih sprememb. Postopek modeliranja je temeljil na metodi SCS Curve Number (CN), pri kateri so bili CN parametri za vsak primer in vsak posamezen scenarij izbrani glede na karte vrste tal in vrste rabe zemljišč. Poleg tega so bili za vsak primer izračunani tudi parametri časovnega zamika na podlagi opredeljenega CN parametra in značilnosti vsakega podporečja. V tej študiji je bilo ugotovljeno, da so dežni vrtovi najbolj učinkovit ukrep glede zmanjšanja odtoka (konica in volumen) na sotočju Glinščice in Gradaščice. Tako zelene strehe kot cisterne za meteorne vode (prostornina~11.4 m3) so pokazale tudi razmeroma dobre rezultate v primerjavi s preostalimi ukrepi. Glede na scenarije (1-8) so zadnje mesto zasedli drenažni pločniki in meteorne cisterne (prostornina~5.7 m3). Podroben postopek modeliranja in končni rezultati raziskave so predstavljeni v celotni nalogi
Proposal for the development of an equation for the synthetic unit hydrograph based on data from Slovenia
No full textV hidrološki praksi se pogosto uporabljajo hidrološki modeli, ki simulirajo površinski odtok in se lahko uporabijo tudi za napovedovanje poplav. Kadar imamo na voljo merjene podatke o padavinah in pretokih, lahko za izdelavo hidrološkega modela uporabimo eno izmed teorij, ki se uporablja za modeliranje, t.j. teorijo hidrograma enote. V praksi pa se pogosto zgodi, da nimamo na voljo vseh podatkov za izdelavo hidrološkega modela in njegovo umerjanje. V tem primeru lahko na podlagi lastnosti porečij oblikujemo sintetični hidrogram enote, ki ga nato uporabimo v postopku hidrološkega modeliranja. V diplomski nalogi smo izbrali dvajset večjih porečij v Sloveniji z znanimi lastnostmi (npr. raba tal, naklon). Za vsako porečje smo zbrali pet največjih dogodkov v obdobju 2000-2020 in posledično na podlagi merjenih padavin in pretokov za vsako porečje določili povprečen čas zakasnitve. Poleg osnovnih lastnosti izbranih porečij, smo jih nekaj, kot je dolžina vodotoka, dolžina vodotoka od profila, ki je najbližji težišču porečja, do iztočnega profila in padec vodotoka, tudi naknadno določili s programom SAGA-GIS. Na podlagi lastnosti porečij smo za posamezno porečje izračunali čas zakasnitve po obstoječih metodah, kot je Snyderjeva metoda, metoda Denver, metoda Tulsa District idr. Omenjene enačbe so bile razvite za območje Združenih držav Amerike, kjer je odziv porečij na padavine lahko drugačen kot v Sloveniji. Posledično je možno sklepati, da bi enačba, razvita na podlagi lastnosti porečij pri nas, podala boljše rezultate hidroloških modelov z vidika ujemanja merjenih in simuliranih pretokov. S tem namenom smo s programskim orodjem R s preizkušanjem več deset različnih primerov enačb, poskušali razviti novo enačbo. Izbrano enačbo, ki je podala najustreznejše rezultate, smo preverili s hidrološkim modelom HEC-HMS, kjer smo uporabili merjene podatke testnega porečja vodotoka Medije. Rezultati so potrdili našo hipotezo, da je enačba razvita na podlagi lastnosti porečij v Sloveniji, ustreznejša.Environmental engineering often uses hydrologic rainfall-runoff models that simulate surface runoff and can be used for flood prediction. One of the methods to set-up hydrologic models is the unit hydrograph theory, which can be used if adequate data about precipitation and discharges is lacking. In practice, sufficient precipitation and discharge data is often not available. In this case, we can obtain results by creating synthetic unit hydrograph, which is based on the characteristics of drainage basins. For the purposes of this graduation thesis we chose twenty larger Slovenian catchments with known characteristics (e.g., land use, slope) and for each catchment five biggest flood events were selected. Based on the characteristics of the catchments we calculated lag time using existing methods such as Synder’s method, Denver method, Tulsa District method, etc. The mentioned equations were developed at the area of the United States of America where the characteristics of the catchments differ from the characteristics of the ones in Slovenia. Consequently, we can conclude that the equation developed based for the catchments in Slovenia could provide more accurate results. With this in mind, we attempted to develop a new equation by testing seventy different cases using R programming language. The selected equation, which gave the most adequate result was further verified with the HEC-HMS hydrological model where we processed data of the additional catchment (i.e. Medija River catchment). The results confirmed our hypothesis, which stated that the equation developed based on the characteristics of the catchments in Slovenia would yield better modelling results
Hydrological analysis of karst springs in Slovenia
Full text linkKras je mogoče najti povsod po Sloveniji, z izjemo Severovzhodnega dela države. Kraški vodonosniki so pomemben vir pitne vode, hkrati pa zaradi sposobnosti hitrega pretakanja vode in morebitnih onesnaževal, predstavljajo ranljiv sistem.
Hidrološka analiza kraških izvirov obsega analizo trendov najmanjših, srednjih in največjih letnih pretokov v 14 kraških izvirih, razporejenih po celotni Sloveniji. Naloga podaja opis nastanka krasa in kraškega vodonosnika, opiše mehanizem polnjenja kraškega vodonosnika in pretakanja vode v njem, opiše vrste kraških izvirov in podaja pregled večjih kraških izvirov v Sloveniji. V nalogi je bila statistična analiza trendov narejena z uporabo Mann-Kendallovega testa in z metodo linearne regresije. S Pettittovim testom je bilo poiskano leto, v katerem pride do nenadne spremembe trenda, na podlagi tega leta pa je bila časovna vrsta razdeljena na dve podvrsti. Linearni trendi srednjih letnih pretokov so bili analizirani tudi za podvrsti. Obravnavane so bile značilnosti hidroloških podatkov. V analizo trendov hidroloških in meteoroloških spremenljivk, so bile zajete popolne časovne vrste podatkov, ki so bile predhodno pregledane, manjkajoče vrednosti pa po potrebi dopolnjene. Obravnavano je bilo spreminjanje temperature vode v 7 kraških izvirih in preverili smo odvisnost med temperaturo vode v kraških izvirih in temperaturo zraka.
Prav tako so bili za izbrane meteorološke postaje ugotovljeni trendi temperature zraka in trendi vsote letnih padavin. V nalogi nas je zanimal tudi vpliv padavin na trende srednjih letnih pretokov.
Rezultati so pokazali statistično značilno upadanje srednjih letnih pretokov v 12 izmed 14 analiziranih kraških izvirih, prav tako se statistično značilni trend upadanja najmanjših letnih pretokov pokaže v 11 od 14 kraških izvirih. Temperatura vode narašča v 5 od 7 izbranih kraških izvirih, od tega v 3 kraških izvirih tudi statistično značilno. Kot leto preloma je bilo največkrat določeno leto 1982.Karst can be found all over the Slovenia with the exception of its northeastern part. Karst aquifers are an important source of drinking water, but due to their characteristics can also be very vulnerable. The Master thesis includes an analysis of annual low, mean and maximum daily discharge or water level trends for 14 karst springs in Slovenia. Time series of 53 years was used in the analysis, with the exception of three karst springs with shorter sets of hydrological data measurements. The process of karst formation, characteristics of karst aquifer and the mechanism of water flow and recharging in the karst aquifer are presented. Additionally, different types of karst springs are described and a general overview of karst springs in Slovenia is given. Statistical analysis of the discharge trends was performed by using the Mann-Kendall test and method of linear regression. Trend change point in mean annual discharge was detected by using the Pettitt test. Detected change point divided the mean annual discharge time series in two separate time series and trend for subseries was analysed.
All time series used in the thesis were previously reviewed and missing values were filled in, so only complete times series of hydrological and meteorological data were used. Trends and changes in water temperature were analysed for 7 karst springs.
Trends in annual amount of precipitation and trends in air temperature for selected meteorological stations were also identified. Correlation between annual amounts of precipitation and discharges were calculated as well.
The results of hydrological analysis show statistically significant decrease in mean annual discharge in 12 of the 14 karst springs that were included in the analysis. Additionally a decreasing trend in annual low discharge values for 11 out of 14 karst springs was detected. Water temperature is increasing in 5 of 7 selected karst springs - for 3 of them the increasing trend is also statistically significant. Year 1982 was most often detected as the change point in the investigated samples
Uporaba analiz sočasnosti pojava padavin pri določanju projektnih pretokov v Sloveniji
No full textCompound events for a long time did not get enough scientific attention, due to the complexity of these occurrences. Yet, taking synchronisation of various natural process into account can significantly improve the reliability and accuracy of modelling, design and prediction of natural disasters. In this thesis the topic of compound events, especially spatial and temporal clustering of precipitation is addressed. The analysis of the rainfall clustering is performed for the Sava River catchment in Slovenia. For the investigation hourly precipitation values obtained from ARSO (Slovenian Environment Agency) were used. Afterwards, hydrological modelling of the Sava River catchment up to the Čatež gauging station was performed using GR4H model with included snow module. Analysis of temporal clustering shown, that 3 hours period before the extreme precipitation event is the most crucial in terms of contributing into antecedent rainfall amount. Spatial clustering analysis performed on both hourly and daily data shown a distinctive clustering of rainfall in space: very strong clustering pattern in the western are of the catchment with rapid drop in clustering radius towards the eastern part. The results from both clustering analysis and hydrological modelling were used in order to obtain a design rainfall event that could be used as an input for hydrological modelling in ungauged catchments. The design rainfall event was obtained by the use of Huff and intensity-duration-frequency (IDF) curves. Final results show that even on such a small area (i.e., around 10,000 km2), very distinctive precipitation clustering patterns, both in space and time, can be noticed and as such they should be included in the future design of the rainfall events in the flood studies of this area. Overall, it is also highly recommended to keep in mind and pay attention to including possible synchronisation of natural events more frequently in scientific research.Zaradi kompleksnosti pojava sestavljeni dogodki dolgo časa niso bili deležni dovolj znanstvene pozornosti, vendar pa lahko upoštevanje sočasnosti pojava različnih naravnih procesov bistveno izboljša zanesljivost in natančnost modeliranja, načrtovanja in napovedovanja naravnih nesreč. V magistrskem delu je obravnavana tematika sestavljenih dogodkov, predvsem prostorskega in časovnega nastopa padavin. Analiza sočasnosti nastopa padavin je bila izvedena za porečje reke Save v Sloveniji. Za raziskavo so bile uporabljene urne vrednosti padavin, pridobljene od Agencije RS za okolje (ARSO). Dodatno je bil izdelan hidrološki model porečja reke Save do vodomerne postaje Čatež z uporabo modela GR4H z vključenim snežnim modulom. Analiza sočasnosti nastopa padavin je pokazala, da je obdobje treh ur pred ekstremnim padavinskim dogodkom ključno pri upoštevanju predhodne količine padavin. Analiza sočasnega prostorskega nastopa, izvedena na urnih in dnevnih podatkih, je pokazala značilno lastnost padavin na območju Slovenije: relativno izrazit vzorec sočastnosti nastopa v zahodnem delu porečja in nekoliko manj izrazit vzorec v vzhodnemu delu. Rezultati analize sočasnosti nastopa padavin in rezultati hidrološkega modeliranja so bili uporabljeni za določitev projektnega padavinskega dogodka, ki se ga lahko uporabi kot vhodni podatek za hidrološki model v primeru nemerjenih porečij. Skupna količina padavin in porazdelitev med dogodkom je bila določena z uporabo Huffove krivulje in krivulje intenzivnosttrajanje-povratna doba (ITP). Končni rezultati kažejo, da je že na relativno majhnem območju (tj. okoli 10.000 km2) mogoče opaziti zelo izrazite vzorce sočasnosti nastopa padavin, tako v prostoru kot v času, in jih je kot take treba vključiti v določanje projektnih padavinskih dogodkov pri izdelavi hidroloških študij. Na splošno je tudi zelo priporočljivo upoštevati in biti pozoren na pogostejše vključevanje morebitne sočasnosti naravnih procesov v znanstvene raziskave
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