KRYŽANOWSKI Andrej: Abrazijska odpornost betonskih površin na vodnih zgradbah
Mentor: prof.dr. Matjaž Mikoš
Somentor: izr.prof.dr. Igor Planinc
zagovor: julij 2009

Povzetek
V disertaciji je obravnavana problematika abrazijske erozije betonov, ki se na vodnih zgradbah pojavlja kot posledica abrazijskega delovanja rinjenih plavin. Ključni problem modeliranja abrazijske erozije v laboratoriju predstavlja težavnost modeliranja ustreznih hidravličnih pogojev za nastanek procesa in razmer ekvivalentnih tistim v naravi ter interpretacija rezultatov meritev, ki praviloma bazira zgolj na kvalitativnih analizah. Validacija rezultatov laboratorijskih raziskav je tako možna samo z izvedbo preskusa v normalnih obratovalnih razmerah v naravi. V prvem delu disertacije smo poskušali razjasniti delovanje vodnega toka z rinjenimi plavinami na izpostavljene dele betonskih površin na vodnih zgradbah in določiti primerne sestave betonov pri čemer smo želeli doseči predvsem ustrezne trdnostne karakteristike preskusnih betonov in njihovo izvedljivost – to je možnost vgradnje izbranih materialov brez posebnih predpriprav. Ker je proces abrazijske erozije sam po sebi izredno kompleksen, smo se v okviru našega dela omejili na raziskavo abrazijske odpornosti betonov z modifikacijami osnovne sestave betonov, vgrajenih na evakuacijskih objektih hidroelektrarn na Savi. V šest polj smo, poleg betona z osnovno sestavo betona, vgradili beton z dodatki polimernega veziva, jeklenih vlaken, poli-propilenskih vlaken ter beton z gumenim agregatom. V drugem delu smo primerjali analizo rezultatov laboratorijskih raziskav in meritve opravljene na poskusnih poljih v naravi. Pri analizi abrazijske odpornosti betonov na vodnih zgradbah je bistvenega pomena ustrezna interpretacija dobljenih rezultatov, ki se je do sedaj največkrat omejevala na primerjalno analizo rezultatov raziskav abrazijske odpornosti, opravljenih po standardnih postopkih v laboratoriju. Abrazijska odpornost je bila analizirana z metodo podvodne abrazije po postopku ASTM C 1138, dobljene rezultate pa smo primerjali z meritvami opravljenimi v naravi na poskusnih poljih izvedenih v podslapju hidroelektrarne Vrhovo – potrjena je bila soodvisnost rezultatov in meritev. V zaključkih v disertaciji ugotavljamo, da lahko, na osnovi meritev obrabe betonov po postopku ASTM C 1138 in ob upoštevanju podobnih hidroloških pogojev ter obratovalnih razmer, ki so veljali v času izvajanja disertacije, napovemo časovni razvoj obrabe betonov na vodnih zgradbah. Rezultati potrjujejo ustreznost metode ASTM C 1138 za napoved razvoja abrazijskih procesov in dinamike obrabe betonskih površin na jezovnih zgradbah elektrarn na Savi.
Ključne besede: hidravlika, hidrotehnični objekti, abrazija, abrazijske poškodbe, abrazijska odpornost, eksperiment, beton
UDK: 627.2/.8:691.32(043.2)

Abstract
The PhD thesis deals with the abrasive wear of concrete occurring in hydraulic structures as a consequence of the abrasive action of waterborne particles. The key problem of modelling abrasive wear under laboratory conditions lies in the difficulty of modelling the proper hydraulic conditions for triggering the process and conditions equivalent to those in the field, as well as the in the interpretation of measuring results, which is, as a rule, based on qualitative analysis only. The validation of the results obtained in the laboratory is therefore possible only by performing tests under normal operational conditions in the field. In the first part of the thesis we tried to define the action of waterborne solid particles to exposed concrete surfaces in hydraulic structures and define the appropriate concrete mixtures, thus trying to obtain the required strength characteristics of the test concretes and their feasibility – the possibility of building-in of the chosen materials without any special preconditioning. Since the process of abrasive wear in itself is a highly complex one, we focused on studying the abrasion resistance of concrete with modifications of the basic composites, built in the evacuation structures of the hydropower plants on the Sava River, Slovenia. The basic composition of concretes built into the six plots was modified by polymer additives, steel fibers, polypropylene fibers, and granular rubber. In the second part we compared the analysis of the results obtained in laboratory simulations and the measurements performed in the test plots in the field. When analysing abrasion resistance of concrete in hydraulic structures the interpretation of the results obtained is of major importance; until now this was usually limited to the comparative analysis of the results of studies on abrasion resistance, which were performed in the laboratory using the standard procedures. Abrasion resistance was investigated using the standard ASTM C 1138 test method of underwater abrasion, and the results were then compared to the measurements performed in the test fields of the stilling basin of the Vrhovo hydropower plant (HPP) – the correlation of the results and measurements was confirmed. In the conclusion, we argue that based on the measurements of concrete wear following the standard ASTM C 1138 and considering similar hydrological and operational conditions at the time of performing the thesis research, a time machine of concrete wear in hydraulic structures can be predicted. The results confirm the adequacy of the ASTM C 1138 method for predicting the advancement of the abrasion processes and the dynamics of wear of concrete surfaces in the dam structures of the Sava River HPPs.
Key words: hydraulics, hydraulical structures, abrasive action, abrasion damage, abrasive resistance, test, concrete
UDC: 627.2/.8:691.32(043.2)

ZORN Matija: Recentni geomorfni procesi na rečno-denudacijskem reliefu na primeru porečja Dragonje
Mentor: izr. prof. dr. Karel Natek
Somentor: prof.dr. Matjaž Mikoš
zagovor: november 2007

Povzetek
Doktorsko delo je prispevek k boljšemu razumevanju geomorfnih procesov v flišnih pokrajinah jugozahodne Slovenije. Predstavljene so meritve erozijsko-denudacijskih procesov v porečju Dragonje. Meritve so potekale od februarja 2005 do maja 2006. Merili smo površinsko spiranje na treh različnih rabah tal, umikanje strmih golih flišnih pobočij, premikanje gradiva po erozijskem jarku in kemično denudacijo v porečju. V manjšem obsegu smo merili še žlebično in vetrno erozijo. Meritve so bile tedenske, rezultati pa so predstavljeni tedensko, mesečno ter po letnih časih in so korelirani z vremenskimi razmerami (padavinami, temperaturami in vetrom).
V porečju je najhitrejše umikanje strmih flišnih pobočij, ki se umikajo skoraj s hitrostjo 5 cm/leto. Premikanje gradiva po erozijskem jarku je skoraj šestkrat počasnejše od sproščanja fliša. Skoraj šestkrat počasnejša pa je tudi hitrost zniževanja površja zaradi površinskega spiranja na goli prsti (~8,5 mm/leto). Zniževanje površja zaradi površinskega spiranja v gozdu (~0,4 mm/leto) je za faktor 130 počasnejše od umikanja strmih pobočij, zniževanje površja na travniku pa je počasnejše za faktor 300 (0,16 mm/leto). Najpočasnejša je kemična denudacija (0,07 mm/leto), ki je kar za faktor 744 počasnejša od umikanja strmih flišnih pobočij.
Ključne besede: geografija, geomorfologija, erozijski procesi, erozija prsti, umikanje pobočij, fliš, rečno-denudacijski relief, Istra, Slovenija
UDK: 911.2:551.435(497.4-14)(043.3)

Abstract
The aim of this doctoral thesis is better understanding of geomorphic processes in flysch landscapes in south-western Slovenia. Measurements of erosion and denudation processes in the Dragonja river basin are presented. They took place weekly between February 2005 and May 2006. We measured (1) interrill erosion on three different land uses, (2) rockwall retreat on steep flysch slopes, (3) movements of debris in erosion gully, (4) chemical denudation and in smaller extend also (5) rill erosion and (6) wind erosion. The results are presented according to weeks, months and seasons and are correlated with weather conditions of that time (precipitation, temperature and wind).
Rockwall retreat on steep flysch slopes, with speed of almost 5 cm/year was the fastest among all measured erosion processes. The slope processes in erosion gully were almost six times slower. Surface lowering due to interrill erosion on bare flysch soil has approximately the same speed as processes in erosion gully (~8.5 mm/year). Surface lowering due to interrill erosion in the forest (~0.4 mm/year) is almost 130 times slower in relation to rockwall retreat and on meadows (0.16 mm/year) 300 times slower in relation to rockwall retreat. Chemical denudation is the slowest process (0.07 mm/year), being 744 times slower than rockwall retreat.
Key words: geography, geomorphology, erosion processes, soil erosion, rockwall retreat, flysch, fluvial-denudational relief, Istria, Slovenia
UDC: 911.2:551.435(497.4-14)(043.3)

KOBOLD Mira : Vpliv napake ocene padavin na napako napovedi odtoka pri napovedovanju poplav
Mentor: prof.dr. Mitja Brilly
Somentor: prof.dr. Jože Rakovec
zagovor: april 2007

Povzetek
    Doktorska disertacija obravnava vpliv padavin, vlažnosti tal in evapotranspiracije na oceno odtoka s povodja Savinje. Za izračun odtoka kot tudi ostalih hidroloških spremenljivk je bil uporabljen švedski konceptualni model HBV, verzija HBV-96. Model smo v letu 2003 v okviru evropskega raziskovalnega projekta “European Flood Forecasting System”, ki je tekel v petem okvirnem programu Evropske skupnosti, prvič implementirali v Sloveniji na povodju Savinje.
    Prikazani so rezultati umerjanja dveh modelov povodja Savinje z različnim časovnim korakom, dan in ura. Za simulacijo odtoka in napoved visokih voda in poplav je primeren model s časovnim korakom ene ure, vendar  število petih ombrografskih postaj na povodju in okolici ni dovolj za točno oceno ploskovnih padavin in zadovoljivo umerjanje modela, saj ima topografija povodja močan vpliv na meteorološko dogajanje v porečju, zlasti v zgornjem toku Savinje. Povprečna relativna napaka pretoka znaša okrog 40 % za celotno območje pretokov, za visokovodne konice pa okrog 25 %. 
    Splošni problem mreže padavinskih postaj je njena neustreznost za hidrološke aplikacije. Z analizo vpliva števila padavinskih postaj na oceno ploskovne količine padavin smo pokazali, da lahko število postaj odločilno vpliva na oceno količine padavin na povodju in s tem na odstopanje simuliranega odtoka od opazovanj. Analize kažejo zlasti veliko odstopanje pri majhni količini padavin na povodju, ko prevladuje nevihtni tip padavin in so padavine običajno lokalno omejene. Napaka pri majhni količini padavin na povodju lahko preseže 100 %. Pri padavinah, ki povzročijo visoke vode in poplave, je relativna napaka manjša, do 50 %. S korigiranjem padavin v modelu HBV smo za nekaj padavinskih dogodkov pokazali, da je ob pravilnem opisu padavin v modelu ujemanje simuliranega pretoka z merjenim dobro. Z analizo prostorske spremenljivosti padavin na povodju Savinje smo izdelali predlog optimalnega števila postaj na povodju z zveznim beleženjem intenzitete padavin za potrebe hidrološkega modeliranja.
    Ker nezadostna mreža ombrografskih postaj na povodju Savinje ne da pravilne ocene ploskovnih padavin, smo v nalogi obravnavali uporabnost radarskih padavin v hidrološkem modeliranju. Analiza dveh padavinskih dogodkov je pokazala, da so trenutne urne akumulacije padavin iz radarskega centra na Lisci neuporabne za modele padavine-odtok, saj so le te podcenjene za faktor 3 do faktor 6.
    Izvedli smo analizo občutljivosti konceptualnih modelov na padavine kot osnovni vhodni podatek v model. Izpeljali smo odvisnost med napako v padavinah in odstopanjem simulirane visokovodne konice zaradi te napake. Odvisnost je polinom drugega reda in ni odvisna od velikosti povodja. Z izpeljano enačbo lahko ovrednotimo odstopanje pretoka konice visokovodnega vala, če vemo, kolikšna je napaka v oceni ploskovne količine padavin. Razmerje med napako pretoka konice visokovodnega vala in napako padavin je pri podcenjenih padavinah pod 1.6, pri precenjenih padavinah pa nad to vrednostjo. Pri precenitvi padavin za 50 % se napaka v odtoku že skoraj podvoji.
    Z analizo poplav iz leta 1980 in leta 1990 smo za povodje Savinje proučili vpliv vlažnosti tal in evapotranspiracije na odtok. V obeh poplavnih dogodkih je bila razporeditev in količina padavin na povodju podobna, pretok poplavnega vala leta 1980 pa za okrog 200 m³/s manjši. Različne začetne hidrološke razmere so povzročile, da je ob nizki predhodni vlažnosti pred poplavnim dogodkom leta 1980 infiltracija v tla predstavljala kar 37 % bruto padavin, pri poplavi leta 1990 pa le 13 %. Evapotranspiracija na poplavne dogodke nima velikega vpliva, v obravnavanih dogodkih je predstavljala le 1 % bruto padavin. Z modelom HBV je bila narejena simulacija poplavnega hidrograma za november 1990 s padavinami iz poplavnega dogodka oktobra 1980, ko je bilo padavin na povodju za 27 mm več kot v dogodku leta 1990. Izračun je pokazal, da bi pretok s temi padavinami dosegel skoraj tisočletno povratno dobo velikih pretokov.
    V zaključnem delu naloge so prikazani rezultati simulacij konceptualnih modelov HEC-1 in HBV in primernost teh dveh modelov za napovedovanje hudourniških poplav s prednostmi in pomanjkljivostmi vsakega od modelov. Izvedli smo še primerjalno analizo vseh obstoječih modelov na povodju Savinje ter podali oceno primernosti za napovedovanje visokih voda in poplav. Prikazane in analizirane so situacije treh padavinskih dogodkov s prognoziranimi padavinami modela ALADIN/SI, med njimi poplava iz novembra 1998. Operativna uporabnost hidroloških napovedi s produkti modela ALADIN/SI je prikazana z rezultati polletnih testnih zagonov modela HBV.
Ključne besede: poplave, padavine, odtok, Savinja, modeliranje, HBV, HEC-1, vlažnost tal, evapotranspiracija, napovedovanje, ALADIN/SI
UDK: 627.51:627.131:551.501:519.87(043.3)

Abstract
    The dissertation treats the influence of precipitation, soil moisture and evapotranspiration on the estimation of runoff from the Savinja catchment. The Swedish conceptual HBV-96 model was used for runoff simulation as well for other hydrological variables. The model was first applied in Slovenia in the year 2003 on the Savinja catchment, in the frame of European research project “European Flood Forecasting System” running under the fifth framework programme of the European Union.
    The results of calibration of two models for the Savinja catchment with two different time steps, day and hour, were presented in the dissertation. The model with time step of one hour is suitable for flash flood forecasting, but five recording raingauges on the catchment and its closeness is not sufficient for accurate estimation of areal precipitation and satisfactory calibration of the model because the topography of the catchment has strong influence on the meteorological happening of the catchment, especially in the upper stream of the Savinja. The average relative error of discharge is about 40 % for the entire range of discharges and 25 % for flood peaks.
    General problem of precipitation network is its unsuitability for hydrological applications. The analysis of number of raingauges on the areal estimation of precipitation has shown that number of raingauges is crucial for the estimation of areal precipitation, what leads to the deviation of simulated runoff from observed values. Analyses show great deviations especially by small amount of precipitation on the catchment when there is storm and usually local precipitation. The relative error can exceed 100 % in the case of small amount of precipitation. The relative error is smaller by precipitation causing high waters and floods and can reach 50 %. The correction of precipitation in the HBV model for some high water events showed that simulated runoff fits with measured one well by proper precipitation input. Analysis of spatial distribution of precipitation on the Savinja catchment gave the proposal of optimal number of recording raingauges on the catchment.
    Insufficient number of precipitation gages does not give the accurate estimation of areal precipitation, therefore the applicability of radar precipitation was treated as input in hydrological modelling. The analysis of two precipitation events has shown that hourly radar accumulations of precipitation from radar centre on Mount Lisca are underestimated for factors between 3 and 6 and thus useless for the rainfall-runoff models.
    The sensitivity analysis of conceptual models on precipitation input was investigated. The relationship between an error in precipitation amount and deviation of simulated peak discharge was carried out. The equation is quadratic polynomial and the relationship is not dependent on the catchment area. Derived equation can be used to asses the deviation of predicted runoff in the case of known deviation in the estimation of areal precipitation. The ratio of errors between peak discharges and underestimated precipitation is under 1.6 and above this value by overestimated precipitation. The error in runoff is almost doubled by 50 % of overestimated precipitation.
    With analysis of floods in 1980 and 1990 on the Savinja catchment the impacts of soil moisture and evapotranspiration on runoff were investigated. In both flood events, the distribution and amount of precipitation were similar on the catchment, but runoff in the year 1980 was about 200 m³/s lower compared to the year 1990. The differences in initial hydrological circumstances caused that 37 % of total precipitation was taken by infiltration into the soil in flood of 1980 and only 13 % in flood of 1990. Evapotranspiration do not have large impact on flood waves, in analysed events the evapotranspiration was only 1 % of total precipitation. Flood hydrograph in November 1990 was simulated by HBV model with precipitation which caused flood in October 1980, which was greater by 27 mm on the catchment. The results of calculation showed that the peak discharge would reach the thousand year return period flood in that case.
    In the final part of the dissertation the results of simulations of conceptual models HEC-1 and HBV were presented. The advantages and disadvantages of both models and their suitability for flash flood forecasting are given. The intercomparison of all models covering the Savinja catchment was carried out. The assessment of suitability of models for flood forecasting is given. Three precipitation events are presented and analysed with predicted precipitation of ALADIN/SI model, one of them is flood from November 1998. Operational applicability of hydrological predictions by products of ALADIN/SI model are presented with the results of half-yearly test runs of the HBV model.
Key words: floods, rainfall, runoff, Savinja, modelling, HBV, HEC-1, soil moisture, evapotranspiration, forecasting, ALADIN/SI
UDC: 627.51:627.131:551.501:519.87(043.3)

BIZJAK Aleš : Sintezni postopek ocenjevanja hidromorfološkega stanja rečnih koridorjev, razvit z analizo stanja na reki Dragonji
Mentor: izr.prof.dr. Matjaž Mikoš
Somentor: prof.dr. Mitja Brilly
zagovor: november 2003

Povzetek
    V raziskavi obravnavamo razvoj nove sintezne metode za oceno hidromorfološkega stanja rečnih koridorjev, izdelane z analizo stanja na reki Dragonji. Izhodišče izdelave nove metode je bila hitrost zajema podatkov in natančnost metode. Pred izvedbo aplikativnega dela raziskave smo zasnovali koncept hitrega transektnega zajema podatkov ter izdelali obsežen hidromorfološki inventarizacijski list s kombiniranim naborom hidromorfoloških spremenljivk v tujini najpogosteje uporabljanih metod, švedske Riparian, Channel and Environmental Inventory, ameriške Stream Visual Assessment Protocol, angleške River Habitat Survey in nemške Gewässerstrukturgütebewertung.
    Terenski zajem podatkov smo izvedli na osnovi hidromorfološkega inventarizacijskega lista v 288 predhodno kartografsko določenih transektih vzdolž teka reke Dragonje na medosni razdalji 100 m in izdelali obsežno podatkovno bazo 148 hidromorfoloških spremenljivk v vsakem izmed transektov.
    Podatkovno bazo smo za potrebe izdelave sintezne metode uredili v bazo 99 diskretnih hidromorfoloških spremenljivk. Z uporabo statističnih orodij (analiza glavnih komponent, multivariatna analiza variance, korelacija) in orodij strojnega učenja (odločitveno drevo) smo jo sistematično reducirali v nabor 52 najpomembnejših hidromorfoloških spremenljivk za oceno hidromorfološkega stanja. Na osnovi pregleda in analize izbranih hidromorfoloških spremenljivk smo določili končni nabor 35 hidromorfoloških spremenljivk in izdelali sintezno metodo za oceno hidromorfološkega stanja rečnih koridorjev. Strukturo in ocenjevalni sistem metode smo prilagodili transektnemu zajemu podatkov in metodo aplicirali v 288 transektih vzdolž reke Dragonje.
    Na osnovi predhodnih rezultatov testiranja omenjenih metod na petih testnih odsekih reke Dragonje in petih testnih odsekih reke Reke smo kot primerjalno metodo v naši raziskavi izbrali nemško metodo Gewässerstrukturgütebewertung (GSGB), ki za izdelavo hidromorfološke ocene potrebuje 32 hidromorfoloških spremenljivk. Metodo smo z originalnim konceptom odsečnega zajema v 111 odsekih in prirejenim transektnim zajemom podatkov v 288 transektih aplicirali vzdolž celotnega teka reke Dragonje.
    S primerjalno analizo ocen odsečnega zajema po nemški metodi in transektnega zajema po nemški in sintezni metodi smo ugotovili, da lahko na primeru reke Dragonje za izdelavo ocene hidromorfološkega stanja rečnega koridorja namesto časovno zahtevnega odsečnega zajema uporabimo hitrejši transektni zajem podatkov, kljub temu da na reki Dragonji skupna dolžina transektov zajame le 20 % skupne dolžine odsekov. Prav tako smo ugotovili, da lahko ocenjevalni sistem transektne sintezne metode uspešno apliciramo tudi v daljših odsekih reke Dragonje.
    Analiza vpliva subjektivnega faktorja, izdelana na osnovi 144 terenskih meritev predhodno šolanih študentov je pokazala, da se v večini testnih transektov glede na izračunane vrednosti t-statistike rezultati študentskih meritev v obeh metodah razlikujejo od rezultatov ekspertnih meritev. Pregled odstopanj vrednosti študentskih meritev od ekspertnih za posamezne spremenjlivke obeh metod je pokazal, da bi bilo potrebno popisovalce hidromorfoloških kakovosti bolj poglobljeno uvajati v tovrstno delo v rečnih koridorjih. Izračun intervalov zaupanja za študentske meritve za obe metodi kaže, da so študentje z manj raztrosa in zanesljiveje določali hidromorfološke kakovostne razrede testnih transektov po sintezni metodi. Primerjalna analiza rezultatov meritev študentov z izračunom H- statistike neparametrskega testa Kruskal - Wallis pa je pokazala, da so študentje tako po metodi GSGB kakor po sintezni metodi določevali podobne hidromorfološke ocene in jih tudi podobno razvrščali v hidromorfološke kakovostne razrede.
Ključne besede: Dragonja, ekohidrologija, hidromorfološko stanje, krajinska ekologija, rečni koridor, terenski poskus, transektni zajem podatkov, urejanje vodotokov
UDK: 504.4.05 + 556.18 + 556.52 / .53 + 556.537 (043.3)

Abstract
    The research deals with the development of a new synthesis method of assessing the hydromorphological status of river corridors, based on state analysis of the Dragonja River. The bases of the new method were time effectiveness of data gathering and accuracy of the method. Prior to the practical research implementation, a concept of a rapid transect data gathering was designed. Additionally, an extensive hydromorphological record sheet was elaborated, including a combined list of hydromorphological variables of the methods most frequently used abroad: the Swedish Riparian, Channel and Environmental Inventory, the American Stream Visual Assessment Protocol, the British River Habitat Survey and the German Gewässerstrukturgütebewertung.
    On the basis of the hydromorphological record sheet, field data gathering was carried out in 288 transects a priori cartographically determined along the Dragonja water course at an axis distance of 100 m. In each of the transects, an extensive data base of 148 hydromorphological variables was designed.
    In order to work out the synthesis method, a data base of 99 discreet hydromorphological variables was prepared. By way of a systematical reduction, a list of 52 most significant hydromorphological variables, according to the results of statistical (Principal Component Analysis, MANOVA, Correlation) and machine learning tools (decision trees) was made. On the basis of reviewing and analysis of the determined hydromorphological variables, a final list of 35 hydromorphological variables was designed. Based on the final list, the synthesis method of assessing the hydromorphological status of river corridors was made. The structure and the assessment system of the method was adapted to the transect data gathering. The method was applied in the 288 transects along the Dragonja River.
    On the basis of the results of applying the mentioned methods in five test reaches of the Dragonja River and five test reaches of the Reka River the German Gewässerstrukturgütebewertung (GSGB) was chosen as the comparison method of the research. For the hydromorphological assessment, this method requires 32 hydromorphological variables. The method was applied along the Dragonja River in two ways, by way of its original concept of data gathering in 111 reaches, and by way of the adapted data gathering in 288 transects.
    The comparison analysis of assessing the data gathering in reaches according to the German method and the transect data gathering according to the German and the synthesis method has shown that in the case of the Dragonja River, the faster transect data gathering can be used instead of the more time consuming data gathering in the river reaches, despite the fact that the sum of the transect lenghts amounts to only 20 % of the total lenght of the reaches. Additionally, it was established that it is possible to successfully apply the assessment system of the transect synthesis method even to reaches of the Dragonja river.
    Analysis of the factor of subjectiveness, conducted on the basis of 144 field measurements of pre-trained students has shown that according to the calculated values of the t-statistics in the majority of the test transects the results of student measurements differ from expert measurements in both methods. A review of deviations of measurements made by students in comparison to the expert measurements has indicated that assessors of hydromorphological qualities should receive a more in-depth introduction into the respective work in river corridors. The calculated confidence intervals for student measurements regarding both methods shows that the students had used the synthesis method with less variance and with a higher level of accuracy determined the hydromorphological quality classes of the transects. A comparison analysis of the results of the student measurements by calculating the H-statistics of the non-parametric Kruskal - Wallis test has shown that the students determined the hydromorphological values as well as hydromorphological quality classes with a high level of similarity in both methods.
Key words: the Dragonja River, ecohydrology, hydromorphological status, landscape ecology, river corridor, field experiment, transect data gathering, river engineering
UDC: 504.4.05 + 556.18 + 556.52 / .53 + 556.537 (043.3)

ŠRAJ Mojca : Modeliranje in merjenje prestreženih padavin
Mentor: prof.dr. Mitja Brilly
Somentor: izr.prof.dr. Matjaž Mikoš
zagovor: marec 2003

Povzetek
    Doktorska disertacija je del obsežnega znanstveno-raziskovalnega projekta “Dragonja: Forest – Water – Soil – Climate Interactions”, ki ga od leta 1999 izvajata univerza Vrije Universiteit iz Amsterdama in Univerza v Ljubljani. Za eksperimentalno povodje je bilo izbrano povodje Dragonje, ki je zanimivo zaradi intenzivnih naravnih procesov zaraščanja površin z gozdom v zadnjih desetletjih, kar je pripeljalo do zmanjšanja pretokov, tako minimalnih kot maksimalnih. Ob tem opaznih padavinskih in temperaturnih sprememb ni bilo zaznati. Glavni namen projekta kot celote je torej ugotoviti vpliv zaraščanja na vodno bilanco celotnega povodja.
    V okviru disertacije so bile narejene natančne meritve in analize posameznih komponent hidrološkega kroga gozda s sodobno mersko opremo, ter različni modeli prestreženih padavin na eksperimentalnem povodju Dragonje. V ta namen sta bili v sodelovanju z univerzo Vrije Universiteit iz Amsterdama, konec leta 1999 v listnatem gozdu na povodju Dragonje izbrani dve merski ploskvi, ena na severnem (1419 m²) in druga na južnem pobočju hriba (615 m²) nad sotočjem Dragonje in Rokave. Meritve so se začele v jeseni 2000. V disertaciji je obravnavano obdobje enega leta od oktobra 2000 do septembra 2001. Na obeh raziskovalnih ploskvah so se merile količine padavin nad krošnjami, količine padavin, ki padejo skozi odprtine med krošnjami oz. kasneje prikapljajo z njih ter delež padavin, ki odtečejo po deblu do tal. Vse naštete količine so se merile avtomatsko z digitalnim zapisovanjem rezultatov na vsakih 10 minut. Padavine nad krošnjami so se merile z ombrografom, za kontrolo pa še s totalizatorji z ročnim praznjenjem. Delež padavin, ki padejo skozi odprtine med krošnjami in listi oz. kasneje prikapljajo z njih, se je meril s po dvema kovinskima žlebovoma v kombinaciji s po desetimi premičnimi totalizatorji na vsaki raziskovalni ploskvi, ki se jih je ročno praznilo in se jim vsakič zamenjalo merilno mesto. Na ta način je bila zajeta tudi prostorska spremenljivost tega deleža padavin. Odtok po deblu se je meril na dveh najbolj tipičnih vrstah dreves na vsaki ploskvi posebej. Na severni raziskovalni ploskvi sta to gaber in hrast, na južni pa jesen in hrast. Okrog vsakega debla je bil speljan žlebič iz gumijaste polcevke. Na vsaki ploskvi posebej so se v desetih posebnih košarah redno zbirale količine odpadlega listja za določitev indeksa listne površine LAI. Z istim namenom in v istih točkah se je izvajalo tudi hemisferično fotografiranje krošenj in tri serije meritev fotosintetskega aktivnega sevanja PAR. Za potrebe določanja indeksa listne površine je bila najpogostejšim vrstam dreves določena specifična površina listov SLA. Hkrati z vsemi temi meritvami so se v okviru celotnega projekta izvajale tudi ostale meritve na povodju, ki so tudi uporabljene v nalogi.
    Indeks listne površine LAI se je določal po treh metodah. Metodi hemisferičnega fotografiranja in merjenja fotosintetskega aktivnega sevanja PAR v obdobju z listjem podcenjujeta vrednosti LAI. Za izračune so bili privzeti rezultati najnatančnejše metode zbiranja odpadlega listja. Dobljeni vrednosti za LAI po tej metodi sta 6,7 za južno pobočje in 7,3 za severno. Manjša vrednost LAI na južnem pobočju je bila pričakovana, saj ima gozd na tem pobočju bolj odprt značaj kot na severni strani.
    Analiza meritev je pokazala, da obravnavano obdobje po količini padavin precej odstopa od 35-letnega povprečja, zlasti v jesenskih mesecih, ko je padlo kar tretjina celotne letne vsote padavin. Intenziteta padavin je bila največja poleti in najmanjša pozimi. Regresijske analize padavin izmerjenih na posameznih dežemerih so pokazale dobro ujemanje s koeficientom korelacije nad 0,95. Regresijske analize meritev deleža padavin, ki padejo skozi odprtine med krošnjami ali kasneje z njih, s stalnimi in premičnimi merilci, so pokazale pričakovane višje vrednosti premičnih merilcev z zelo visokimi koeficienti korelacije. Povprečna vrednost tega deleža padavin znaša 67,1 % za južno in 71,5 % za severno raziskovalno ploskev. Izmerjene vrednosti so primerljive z rezultati podobnih raziskav oz. so za približno 10 % nižje. Povprečni delež odtoka po deblu znaša 4,5 % na južni strani in 2,9 % na severni. Razlika je posledica različne strukture in lastnosti gozda na obeh pobočjih. Na osnovi meritev in bilančne enačbe je bilo ugotovljeno, da znašajo povprečne letne izhlapele prestrežene padavine 28,4 % za južno in 25,4 % za severno ležeče pobočje. Torej več kot četrtina padavin padlih nad gozdom izhlapi nazaj v ozračje. Vrednosti so precej visoke v primerjavi z izhlapelimi prestreženimi padavinami listopadnih gozdov, ki se ponavadi gibljejo med 15 in 25 %.
    Podobne rezultate dobimo tudi z različnimi modeli prestreženih padavin. Pri modeliranju so bili uporabljeni tako obstoječi,  kot na novo izdelani modeli. Modelirane vrednosti so se v splošnem dobro ujele z meritvami. Odstopanja so bila v mejah standardne napake. Izjema je le model, pri katerem je bila intenziteta izhlapevanja z mokrih krošenj izračunana po Penman-Monteithovi enačbi. Tako izračunane vrednosti intenzitete izhlapevanja so močno podcenjene, kar so potrdile že mnoge raziskave v mokrih priobalnih pogojih. Iz tega lahko povzamemo, da Penman-Monteithova enačba kljub svoji natančnosti in visoki zahtevi po podatkih ni primerna za izračun izhlapevanja prestreženih padavin z mokrih krošenj gozda v danih klimatskih pogojih.
    V disertaciji je dokazan velik vpliv južnih vetrov na količine izhlapelih prestreženih padavin. Iz tega razloga je bil izdelan nov model, ki mu je bil dodan vpliv toplih južnih vetrov. S tem smo podcenjevanje izhlapelih prestreženih padavin po Penman-Monteithu odpravili.
    V zaključnem delu disertacije je izdelana še razlika v vodni bilanci glede na rabo kmetijskih površin v letih 1948 in 1988. Vzrok za razliko v bilanci so spremembe v količini prestreženih padavin na površinah poraščenih z gozdom in obdelovalnih površinah. Za prestrežene padavine na kmetijskih površinah je privzeta koruza, ker so bili v literaturi parametri zanjo podani najnatančneje in ker so prestrežene padavine koruze v primerjavi z drugimi poljščinami zaradi velike pokrovnosti in indeksa listne površine sorazmerno velike. Izračuni so pokazali, da se je količina površinskega odtoka med letoma 1948 in 1988, zaradi spremembe v rabi površin, zmanjšala za 4,3*10⁶ m³, kar predstavlja 40,5 % zmanjšanje.
Ključne besede: prestrežene padavine, indeks listne površine, LAI, Gash, modeliranje, Dragonja, terenske meritve, hidrologija, veter
UDK: 551.506+551.508+556.12/.13.08+556.51+630.11(282.249Dragonja)(043.3)

Abstract
    The thesis is a part of an extensive scientific-research project “Dragonja: Forest – Water – Soil – Climate Interactions”, which has been carried out by Vrije University from Amsterdam and University of Ljubljana since 1999. The Dragonja watershed was chosen as an experimental watershed, since it is interesting because of the intensive natural reforestation in the last decades, which has caused a decrease in minimal and maximal flows. At the same time no noticeable precipitation and temperature changes have been perceived. The main intention of the project is to figure out the impact of reforestation on the water balance of the entire watershed.
    In the frame of the thesis, precise measurements and analysis of individual components of the forest hydrological cycle were made. Contemporary measurement equipment was used and different rainfall interception models were applied on the experimental watershed of Dragonja. For this reason, two forest plots in the deciduous forest above confluence of the Dragonja and Rokava rivers were selected at the end of the year 1999 in co-operation with Vrije University from Amsterdam. One is located on the north-facing slope (1419 m²) and other on the south-facing slope (615 m²). Measurements started in autumn 2000. The thesis describes the result of a one-year period from October 2000 till September 2001. Precipitation above the canopy, throughfall and stemflow were measured on both research plots. All mentioned quantities were measured automatically with digital recording of results every 10 minutes. Rainfall above the canopy was measured with a tipping bucket rain gauge and with a totalisator (manual gauge) for control. Throughfall was measured with two steel gutters in combination with ten manual gauges, which were emptied and moved randomly every time. The spatial variability of throughfall was captured in this manner. Stemflow was measured on two most typical species in each plot. In the north plot oak and hornbeam trees were selected, and ash and oak trees in the south plot. Each tree was fitted with a rubber collar around the stem. Litter was collected regularly in 10 baskets in each plot for LAI estimation. For the same purpose and at the same points, hemispherical photographs of canopies were taken and three series of measurements of photosynthetically active radiation (PAR) were made. The specific leaf area SLA was estimated for the main species for need of estimating the leaf area index. At the same time in the frame of the entire project, other measurements, used in this thesis, were carried out in the watershed.
    The leaf area index LAI was estimated by three methods. The method of hemispherical photography and photosynthetically active radiation PAR measurements underestimated LAI values in the foliated period. Results of litterfall collection, the most accurate method, were used for further calculations. The obtained values of LAI were 6.7 and 7.3 for the south and north slope, respectively. A smaller value of LAI on the south slope was expected, because of the more open character of this forest.
    Analysis of the measurements showed that the observed period deviates considerably in the amount of precipitation compared to the 35-year average, especially in the autumn months, when one third of the entire annual sum of precipitation fell. The largest intensity was in the summer months and the smallest in winter. Regression analyses of precipitation measured on individual rain gauges showed good agreement with a correlation coefficient over 0,95. Regression analyses of the measured throughfall with fixed and roving gauges gave expected higher values of roving gauges with very high correlation coefficients. The average value of this proportion of precipitation amounts to 67.1 and 71.5 % for the south and north research plot, respectively. The measured values are comparable with the results of similar researches, or else they are about 10 % lower. The average stemflow fraction amounts to 4.5 and 2.9 % of the associated rainfall for the southern and northern plot, respectively. The difference is a consequence of the different structure and characteristics of forests on both slopes. On the basis of the measurements and water balance equation, it was calculated that the average annual interception losses amount to 28.4 and 25.4 % for the south and north slope, respectively. So more than one fourth of the precipitation falling above the forest evaporates back to the atmosphere. The values are rather high compared with the interception losses of deciduous forests, which are usually between 15 and 25 %.
    Similar results were also obtained with different models of interception. For modelling, both the existing and the newly created models were used. The modelled values were in general well fitted to the measured values. Deviations were within the standard error. The only exception was the model, which calculated evaporation rate from the wet canopy based on the Penman-Monteith equation. Those values were strongly underestimated, as has already been confirmed by many researches in wet maritime conditions. We can summarise that the Penman-Monteith equation, despite its accuracy and very high data demand, is not appropriate for the calculation of interception losses from a wet canopy in the given climatic conditions.
    The thesis has proved the large impact of south winds on amounts of interception loss. For this reason a new model was created, which takes into account the influence of warm south winds. Thus, underestimation of interception losses based on the Penman-Monteith equation was eliminated.
    In the final part of the thesis the difference in water balance based on land use in the years 1948 and 1988 was made. Changes in the amount of interception on forested and agricultural areas result in differences in the water balance. Corn was adopted as a reference crop on agricultural areas, because its parameters were represented in the literature most accurately and because the interception of corn on account of the large canopy cover and leaf area index are relatively large compared with other crops. Calculations showed that the quantity of surface runoff between the years 1948 and 1988, because of changes in land use, was reduced by 4.3*10⁶ m³, which represents a 40.5 % reduction.
Key words: interception precipitation, leaf area index, LAI, Gash, modelling, Dragonja, field measurements, hydrology, wind
UDC: 551.506+551.508+556.12/.13.08+556.51+630.11(282.249Dragonja)(043.3)

PETKOVŠEK Gregor : Kvantifikacija in modeliranje erozije tal z aplikacijo na povodju Dragonje
Mentor: izr.prof.dr. Matjaž Mikoš
Somentor: izr.prof.dr. Matjaž Četina
zagovor: september 2002

Povzetek
    Naloga obravnava procese erozije tal in odplavljanja zemljin z eksperimentalnega povodja Dragonje v celoti ali pa enega njegovih delov. Na podlagi meritev v zadnjih treh letih smo določili stopnje sproščanja s klifov, ki so najpomembnejši točkovni vir sedimentov. Merili smo tudi odplavljanje sedimentov in padavine, ter določili njihovo erozivnost. Z modelom na podlagi enačbe RUSLE, ki smo ga izdelali sami, smo ocenili sproščanje zemljin zaradi vodne erozije s površinskih virov, med katerimi so najpomembnejše kmetijske površine. Uporabili smo tudi zgodovinske podatke o padavinah in rabi tal, s pomočjo katerih smo ocenili trende erozivnosti padavin in sproščanja zemljin v povodju.
    Meritve so vključevale meritve padavin na petih lokacijah, meritve pretokov in vzorčevanje vode na povodju Rokave (največji pritok Dragonje v zgornjem delu povodja), ter meritve erozije na klifih. Vzorcem vode je bila določena vsebnost trdnih snovi in na ta način določen pretok lebdečih plavin. Pokazalo se je, da je skupni letni odtok lebdečih plavin okrog 1500 ton, od tega klifi prispevajo nekaj 100 m³ sedimentov v obliki drobnejših frakcij. Premeščanje rinjenih plavin se vrši bržkone le enkrat letno; letna prodonosnost  je reda 100 m³. Primerjali smo več metod za oceno koeficienta odplavljanja. Kot najprimernješa se je pokazala prirejena metoda USLE-M. Koeficient odplavljanja v merskem prerezu znaša slabih 10 %.
    Erozivnost padavin na območju povodja Dragonje znaša med 2500 (osrednji del povodja) in 3500 MJ/ha mm/h (povirje). Na določenih lokacijah je letna erozivnost presegla 5000 MJ/ha mm/h. Pri tem igra pomembno vlogo mikrolokacija. Erozivnost padavin je največja tik nad sotočjem Dragonje in Rokave, to je tam, kjer se iz doline strmo vzpne sleme, na katerem leži vas Labor. Tam je lokalno največja ne le količina padavin, temveč tudi njihova intenziteta. V obdobju meritev 2000-2002 je največja polurna intenziteta na tej lokaciji presegla 100 mm/h. Močni nalivi z veliko erozivnostjo se pojavljajo poleti in jeseni, medtem ko v zimskih in pomladanskih mesecih prevladujejo manj intenzivna dolgotrajnejša deževja.
    V okviru naloge smo razvili tudi enačbo za napovedovanje mesečne erozivnosti padavin na podlagi dnevnih padavin. Pokazalo se je, da je najustreznejši parameter vsota kvadratov dnevnih padavin, pomnožena s koeficientom, ki se mesečno spreminja in približno sledi srednji mesečni temperaturi. Na ta način smo lahko izvrednotili erozivnost padavin na lokacijah in v obdobjih, ko še niso bili na razpolago podatki o padavinah v 5-minutnih intervalih. Ugotovili smo, da v zadnjih desetletjih letna erozivnost padavin upada.
    Model erozije tal smo zasnovali tako, da ga lahko vključimo v obstoječi Šifrant prispevnih površin Republike Slovenije. Model temelji na enačbi RUSLE in na erozijskih enotah, od katerih ima vsaka enotno rabo tal in vsa pripada isti prispevni površini. Model smo aplicirali na zgornjem delu povodja. Pokazalo se je, da lahko največje sproščanje pričakujemo na parcelah, kjer so vinogradi (50 t/ha/leto) ter sadovnjaki in njive (okrog 20 t/ha/leto). Primerjava z Gavrilovićevo enačbo je pokazala, da se vrednosti razlikujejo za približno faktor 2. Če namesto mreže erozijskih enot uporabimo mrežo pravokotnih celic (raster), so pri velikosti obravnavanega območja nad 10 km² razlike zanemarljive. Glede na spremembe rabe tal in erozivnosti padavin od šestdesetih let do danes smo ugotovili, da se je sproščanje zaradi samo površinske vodne erozije tal prepolovilo, če pa upoštevamo še erozijo s klifov, je zmanjšanje še večje (velja za podpovodje Rokave).
Ključne besede: erozija tal, Dragonja, eksperimentalno povodje, erozivnost padavin, modeliranje, RUSLE, GIS, raba tal
UDK: 551.311.2:556.51(282.249 Dragonja)(043.3)

Abstract
    The thesis presents a study of the processes of soil erosion and sediment transport in the Dragonja experimental catchment or some of its parts. Measurements in the last three years were a basis for estimation of the sediment production from cliffs, which are the most important point sources of sediment in the area. Sediment yield and rainfall were also measured. A numerical model, based on Revised Universal Soil Loss Equation, was developed to assess sediment production from areal sources, especially agricultural areas. Historical data on precipitation and land use was used to determine the trends in rainfall erosivity and soil erosion rates in the catchment.
    Measurements included rainfall measurements on five locations, discharge measurements and sediment sampling in the Rokava catchment (the biggest tributary in the upper part of the Dragonja catchment) and monitoring of sediment production from cliffs. The discharge of suspended sediment was determined from suspended sediment samples and turned out to be around 1500 tonnes per year. Cliffs contribute a few 100 m³ of suspended sediment per year to the stream. Annual bed load transport can be estimated to about 100 m³ of bed load sediment per year. Sediment yield and delivery ratio was calculated using different procedures. A variation of USLE-M gave best results. Sediment delivery ratio in the gauged cross section was found to be around 10%.
    Rainfall erosivity in the Dragonja catchment varies between 2500 MJ/ha mm/h (central part) and 3500 MJ/ha mm/h (upper part). In the year 2001, erosivity exceeded 5000 MJ/ha mm/h in one of the monitored locations just above the confluence of Dragonja and Rokava. At this point, a ridge rises steeply from the valley. There, not only the highest amount of precipitation has been recorded, but also the highest intensity. In the monitored period from autumn 2000 till now, the highest half-hour intensity in this location exceeded 100 mm/h. Intensive storms with high rainfall erosivity occur during summer and autumn, while winter and spring storms tend to be longer and have lower intensity.
    Furthermore, the equation for calculating monthly rainfall erosivity form daily precipitation data was developed. The most suitable parameter was found to be the sum of squares of daily precipitation, multiplied by a coefficient that varies from month to month, and approximately follows the mean temperature of a month. This equation enabled us to determine rainfall erosivity in the periods and the locations where 5-minute interval precipitation data was not available. This way, long term trends in rainfall erosivity were determined, which show a slow decline during the last few decades.
    Soil erosion model was developed in such a way that it can be used with the existing Watershed Coding System of the Republic of Slovenia. The base of the model is the RUSLE equation, applied to erosion units. Each erosion unit has a uniform land use. The model was applied to the upper part of the catchment. The results show that the highest soil loss can be expected in vineyards (50 t/ha/y), orchards and fields (20 t/ha/y). A comparison with the Gavrilović equation showed that the latter gives the rates that are about half of those of RUSLE. If square grid modelling approach is applied instead of erosion units, the differences are very small when models are applied to an area of the size of 10 km². The change in erosion rate from the sixties till present was determined based on land use and rainfall erosivity trends. Erosion rate form areal sources has halved, while erosion rate from cliffs (refering to Rokava subcatchment only) has decreased even more.
Key words: soil erosion, Dragonja, experimental catchment, rainfall erosivity, modelling, RUSLE, GIS, land use
UDC: 551.311.2:556.51(282.249 Dragonja)(043.3)

DOKTORSKE DISERTACIJE V DELU