Ce travail a consisté à développer un modèle de canopée (CIM), qui pourrait servir d’interface entre des modèles méso-échelles de calcul du climat urbain et des modèles micro-échelles de besoin énergétique du bâtiment. Le développement est présenté en conditions atmosphériques variées, avec et sans obstacles, en s’appuyant sur les théories précédemment proposées. Il a été, par exemple, montré que, pour être en cohérence avec la théorie de similitude de Monin-Obukhov, un terme correctif devait être rajouté au terme de flottabilité de la T.K.E. CIM a aussi été couplé au modèle méso-échelle WRF. Une méthodologie a été proposée pour profiter de leurs avantages respectifs (un plus résolu, l’autre intégrant des termes de transports horizontaux) et pour assurer la cohérence de leurs résultats. Ces derniers ont montré que ce système, en plus d’être plus précis que le modèle WRF à la même résolution, permettait, par l’intermédiaire de CIM, de fournir des profils plus résolus près de la surface. / This study consisted in the development of a canopy model (CIM), which could be use as an interface between meso-scale models used to simulate urban climate and micro-scale models used to evaluate building energy use. The development is based on previously proposed theories and is presented in different atmospheric conditions, with and without obstable. It has been shown, for example, that to be in coherence with the Monin-Obukhov Similarity Theory, that a correction term has to be added to the buoyancy term of the T.K.E. CIM has also been coupled with the meteorological meso-scale model WRF. A methodology was proposed to take advantage of both models (one being more resolved, the other one integrating horizontal transport terms) and to ensure a coherence of the results. Besides being more precise than the WRF model at the same resolution, this system allows, through CIM, to provide high resolved vertical profiles near the surface.

Les bâtiments représentent 40 pourcents de la consommation finale d'énergie. Ils sont ainsi le fer de lance des politiques de réduction des dépenses énergétiques. Récemment, des systèmes de modèles climatiques qui incluent un modèle atmosphérique régional et des paramétrisations urbaines sophistiquées ont été développés. Ils considèrent la complexité de l’îlot de chaleur urbain et ses interactions avec les besoins énergétiques des bâtiments. Dans quelle mesure ces systèmes constituent-ils des outils d’aide à la décision pour les autorités locales ? Cette étude menée sur le territoire de l'Eurodistrict (Strasbourg - Kehl) en 2010, puis en 2030, à l’aide du système de modèles de climat WRF/ARW-BEP+BEM a démontré que si le système de modèles estimait de manière fiable les besoins en chauffage des bâtiments, ces derniers étaient davantage sensibles aux caractéristiques intrinsèques des bâtiments qu'aux formes urbaines et à l'îlot de chaleur urbain induit par ces formes. / Buildings represent 40 percent of the end-use energy. Thus, they constitute a key point of the energy saving policies. Recently, climate modeling systems that include a mesoscale atmospheric model, sophisticated urban parameterizations have been developed to account for the complexity of the urban climate and its interactions with the building energy loads. This study aims to assess the capability of such climate modeling systems to provide climate and energy guidelines to urban planners. For this, we used the research collaborative WRF/ARW-BEP+BEM climate modeling system and performed sensitivity tests considering the territory of the Eurodistrict in 2010, and then in 2030. The results reveal that the climate modeling system achieves estimating the building energy needs over the study area, but also indicate that the building energy needs are more sensitive to the building intrinsic properties and occupant behavior than to the urban forms and their induced urban heat island.

Les projections climatiques prévoient une amplification du réchauffement climatique, potentiellement exacerbée en milieu urbain du fait du phénomène d’îlot de chaleur urbain. La recrudescence d’évènements extrêmes comme les canicules peut avoir des conséquences écologiques, sanitaires, et économiques dramatiques à l’échelle des villes qui concentrent la population. Parmi les mesures d’adaptation visant à améliorer le confort climatique et la demande énergétique, la climatisation et le verdissement urbain constituent deux leviers d’action aux effets parfois antagonistes. Ce travail de thèse – mené dans le cadre des trois projets de recherche CLIM2, MUSCADE et VegDUD, propose d’évaluer ces effets par des simulations du climat urbain à l’échelle de l’agglomération parisienne. La modélisation repose en particulier sur le modèle de canopée urbaine TEB qui permet de simuler les échanges de chaleur, d’eau et de quantité de mouvement entre les surfaces urbaines et l’atmosphère, et depuis peu l’énergétique des bâtiments et des indices de confort thermique dans les bâtiments et dans les rues. Afin d’améliorer la prise en compte de la végétation urbaine dans TEB, un modèle de toitures végétalisées extensives a tout d’abord été développé et évalué. Différentes pratiques d’arrosage de la végétation urbaine au sol ou sur les toits ont également été paramétrées. Les scénarios d’adaptation de la ville de Paris par la climatisation, évalués dans le cadre de CLIM2 pour la canicule 2003 par des simulations couplées de TEB avec un modèle atmosphérique, ont mis en évidence que toutes les formes de climatisation qui rejettent de la chaleur dans l’atmosphère (sèche ou humide) génèrent une augmentation de la température des rues au niveau des piétons. Ce réchauffement, proportionnel à la puissance des rejets de chaleur sensible dans l’atmosphère, est en moyenne de 0.5 à 2°C, selon le niveau de déploiement de la climatisation. Différentes stratégies de verdissement ont ensuite été mises en œuvre et évaluées toujours sur Paris, en faisant varier soit la végétation au sol (plusieurs taux et types de végétation testés), soit celle en toiture (avec ou sans arrosage), soit les deux. Ces simulations, réalisées dans la configuration générale du projet MUSCADE, i.e. en mode forcé avec une version de TEB disposant d’un générateur dynamique d’îlot de chaleur urbain, ont montré que l’augmentation de la couverture végétale au sol a un pouvoir rafraîchissant plus efficace que les toitures végétalisées, et ce d’autant plus que le taux de verdissement et que la proportion d’arbres sont importants. Les toitures végétalisées quant à elles constituent le moyen le plus efficace de réduire la consommation d’énergie, non seulement estivale mais aussi à l’échelle annuelle, essentiellement grâce à leur pouvoir isolant. / Climate projections predict an amplification of global warming, potentially exacerbated in urban areas by the urban heat island effect. More frequent extreme events such as heat waves may have severe public health, ecological, and economic consequences as cities concentrate population. Among the measures aiming at improving thermal comfort or energy demand, air conditioning and urban greening are measures that may have antagonistic effects. This PhD work is undertaken within the framework of three research projects, CLIM2, MUSCADE and VegDUD. Its objective is to evaluate the respective effects of air conditioning and urban greening based on urban climate simulations across the Paris area. The modelling relies on the Town Energy Balance (TEB) model, which simulates the exchange of heat, water and momentum between the urban surface and the atmosphere. It has been recently improved to simulate building energetics, as well as indoor and outdoor thermal comfort indices. To improve the description of urban vegetation within TEB, a green roof model has been developed and evaluated. In addition, watering practices have been implemented to model the watering of urban vegetation at ground or roof level. Within CLIM2, the air conditioning scenarios tested for adapting Paris city to the extreme temperatures of the 2003 heatwave have been evaluated based on simulations using TEB coupled with an atmospheric model. Results shows that all forms of conditioning that release waste heat (dry or wet) into the atmosphere generate a temperature increase in the streets. This warming is proportional to the power of the sensible heat releases in the atmosphere and is on average 0.5 to 2_C, depending on the level of deployment of the air conditioning. Then, the greening of Paris city has been evaluated based on simulations carried out with the general configuration of the MUSCADE project, i.e. with climate forcings and a dynamic urban heat island generator. The scenarios tested consisted in an increase in ground-base vegetation or an implementation of green roofs on compatible buildings, or the two combined, with the option of watering green roofs or not in summer. Results show that increasing the ground cover has a stronger cooling effect than implementing green roofs, and even more so when the greening rate and the proportion of trees are important. The green roofs are however the most effective way to reduce energy consumption, not only in summer but also on an annual basis, mainly due to their insulating properties.

De par ses caractéristiques, l’environnement urbain influe significativement sur le climat observé dans et à la périphérie des villes. Il est communément admis que le centre des villes présente fréquemment des températures d’air plus élevées que celles mesurées dans les zones rurales environnantes. Ce phénomène appelé îlot de chaleur urbain intéresse les enjeux relatifs à la santé publique, au confort urbain et à la demande énergétique. Ce travail de thèse propose de caractériser le phénomène d’îlot de chaleur à partir de l'association d'un zonage climatique et de mesures mobiles à haute résolution spatiale dans la canopée urbaine. Il repose sur une approche méthodologique en trois temps. Une classification climatique ("Local Climate Zones" (LCZ)) est tout d'abord appliquée à l'agglomération de Nancy. Ce découpage climatique du territoire sert de support à la réalisation de mesures embarquées effectuées en période estivale à l'aide d'un véhicule instrumenté. Celles-ci ont pour but d'observer in situ les spécificités climatiques des LCZ recensées dans l'agglomération. L'association d'une base de données de relevés météorologiques et de la classification LCZ permet de caractériser le comportement climatique du milieu urbain et de comparer le comportement de différentes typologies de quartiers en présence d'un îlot de chaleur urbain. Cette démarche propose également un cadre théorique pour le développement d'un modèle de diagnostic à partir d'indicateurs urbains et climatiques, avec la perspective de construction d'un outil de prise en compte de l'îlot de chaleur dans le processus de planification urbaine / Urban environment impacts significantly the climate observed within and around cities. In this context, city centers frequently present higher air temperatures than those measured in the rural areas nearby. This phenomenon called urban heat island impacts major issues such as public health, urban comfort and energy demand. This Ph.D. thesis proposes to characterize the urban heat island phenomenon based on the combination of a climatic zoning and high spatial density mobile measurements performed within the urban canopy layer. This study is divided into three steps. A climate classification ("Local Climate Zones" (LCZ)) is first applied to the conurbation of Nancy, France. This climatic zoning is used in order to perform mobile measurements thanks to an instrumented vehicle. These measurements target to observe the climatic patterns of the LCZ built in this conurbation. The combination of meteorological database and LCZ classification scheme allows to characterize the urban climate behavior and to compare the thermal behavior of different neighbourhood types. This approach provides a theoretical framework for the development of a diagnosis model based on urban and climatic indicators. It also brings outlooks regarding the building of a decision-support tool that aims to supply information about urban heat island adapted to the urban planners needs

Climate change is a collective action problem that has been seen as something that needs a global solution. This has resulted in multilateral agreements, such as the Paris Agreement, which can largely be said to have been unsuccessful so far. This has led to an increased awareness of the potential of cities as being part of the solution. Cities are often seen as key sources of climate change, but also as key sites for climate action. The Paris Agreement needs to be implemented on all political levels to be effective. This makes cities an important site for climate policy implementation. Some scholars of urban climate governance have looked at ways to evaluate climate policies in cities as a way to improve these processes. This study means to contribute to that field. The aim of the study is to evaluate climate policies in the city plans of Stockholm and Dublin. This has been done by testing an analytical framework which made it possible to shed light on the strengths and weaknesses of the climate policies and the governance structures in the plans. By doing this it was also possible to identify challenges in using the framework and give suggestions on how the framework can be improved. The study takes the form of a comparative case study of the two cities. Document analysis was used as a method to select and analyse the data and the empirical material consisted of the city plans of Stockholm and Dublin. These are policy documents containing general development plans of the cities. It was concluded that both plans contain both strengths and weaknesses. Examples of strengths are that both plans are well-integrated with activities on the regional and national level, that responsibility for implementation is centralised on the local level, that the plans promote innovation and that the plans are connected to long-term goals and visions. Examples of weaknesses are that neither plan makes use of more hard methods such as regulation, that the Dublin City Plan is not integrated with policy on the global level and that the Stockholm City Plan lacks monitoring systems. Regarding the analytical framework it was concluded that it can be used to analyse city plans rather than metropolitan plans. By testing the framework it was also possible to identify challenges in using the framework and give suggestions on how to improve it, such as by making some of the key attributes of the plan more widely applicable.

<p>Тема&nbsp; докторске&nbsp; дисертације&nbsp; је&nbsp; примена&nbsp; и&nbsp; процена&nbsp; класификационог&nbsp; система&nbsp; локалних климатских&nbsp; зона&nbsp; (ЛКЗ)&nbsp; помоћу&nbsp; аутоматизованог&nbsp; модела&nbsp; и&nbsp; биоклиматских&nbsp; анализа&nbsp; на примеру&nbsp; Новог&nbsp; Сада&nbsp; (Србија).&nbsp; Развијени&nbsp; ГИС&nbsp; модел&nbsp; се&nbsp; показао&nbsp; као&nbsp; адекватан&nbsp; за мапирање и дефинисање&nbsp; ЛКЗ у Новом Саду и његовој околини издвојивши чак 13 ЛКЗ употребом 7&nbsp; параметара градске површине.&nbsp; Осим тога,&nbsp; у&nbsp; оквиру дисертације је приказан и развијен нов модел за чишћење базе података. Добијени&nbsp; резултати&nbsp; су&nbsp; указали&nbsp; да&nbsp; се&nbsp; најизраженије&nbsp; разлике&nbsp; у&nbsp; средњој температури&nbsp; ваздуха&nbsp; (Т_ср)&nbsp; јављају&nbsp; између&nbsp; локалних&nbsp; климатских&nbsp; зона&nbsp; (ЛКЗ)&nbsp; ноћу&nbsp; током топлотног таласа и износе до 5,5 &deg;C (ЛКЗ_2-А, разлика између урбане збијене средњеградње и густе шуме изван града). На годишњем нивоу разлике у Т_ср износе 1,7 &deg;C између града и<br />природне&nbsp; околине,&nbsp; односно&nbsp; 0,7&nbsp; &deg;C&nbsp; унутар&nbsp; различитих&nbsp; градских&nbsp; ЛКЗ.&nbsp; Статистичком анализом&nbsp; средњих&nbsp; максималних&nbsp; и&nbsp; апсолутно&nbsp; максималних&nbsp; температура&nbsp; ваздуха&nbsp; на годишњем,&nbsp; сезонском&nbsp; и&nbsp; месечном&nbsp; нивоу&nbsp; нису&nbsp; уочене&nbsp; знатне&nbsp; разлике&nbsp; између&nbsp; ЛКЗ. Учесталост&nbsp; појаве&nbsp; температурних&nbsp; индекса&nbsp; је&nbsp; указала&nbsp; да&nbsp; тзв.&nbsp; &bdquo;хладни&nbsp; индекси&ldquo;&nbsp; (мразни дани,&nbsp; ледени&nbsp; дани)&nbsp; указују&nbsp; на&nbsp; температурне&nbsp; специфичности&nbsp; ЛКЗ&nbsp; у&nbsp; Новом&nbsp; Саду,&nbsp; док&nbsp; то није&nbsp; евидентно&nbsp; анализом&nbsp; тзв.&nbsp; &bdquo;топлих&nbsp; индекса&ldquo;&nbsp; (летњи&nbsp; дани,&nbsp; тропски&nbsp;&nbsp; дани),&nbsp; изузев тропских&nbsp; ноћи.&nbsp; Анализом&nbsp; релативне&nbsp; влажности&nbsp; ваздуха&nbsp; је&nbsp; уочено&nbsp; да&nbsp; постоје&nbsp; знатне разлике између изграђених и природних ЛКЗ, док то није случај између изг рађених ЛКЗ. У Новом Саду се јавља тзв. &bdquo;урбано&nbsp; острво сувоће&ldquo; ноћу током топлотног таласа када је збијена средњеградња (ЛКЗ 2)&nbsp; окарактерисана са максималним дефицитом влажности од око&nbsp; 33%&nbsp; у&nbsp; односу&nbsp; на&nbsp; природну&nbsp; ЛКЗ&nbsp; А&nbsp; изван&nbsp; града.&nbsp; Статистичка&nbsp; анализа&nbsp; вредности израчунатих&nbsp; биоклиматских&nbsp; индекса&nbsp; PET&nbsp; и&nbsp; UTCI&nbsp; је&nbsp; указала&nbsp; да&nbsp; се&nbsp; ЛКЗ&nbsp; разликују&nbsp; у&nbsp; условима&nbsp; спољњег&nbsp; термалног&nbsp; комфора&nbsp; човека&nbsp; на&nbsp; годишњем,&nbsp; сезонском&nbsp; и&nbsp; месечном нивоу,&nbsp; као&nbsp; и&nbsp; током&nbsp; топлотног&nbsp; и&nbsp; хладног&nbsp; таласа&nbsp; (до&nbsp; максималних&nbsp; 8-9&nbsp; &deg;C).&nbsp; Такође&nbsp; су резултати указали&nbsp; да је класификациони систем&nbsp; ЛКЗ адекватан за интер-урбану анализу градске климе (поређења између градова).</p> / <p>Tema&nbsp; doktorske&nbsp; disertacije&nbsp; je&nbsp; primena&nbsp; i&nbsp; procena&nbsp; klasifikacionog&nbsp; sistema&nbsp; lokalnih klimatskih&nbsp; zona&nbsp; (LKZ)&nbsp; pomoću&nbsp; automatizovanog&nbsp; modela&nbsp; i&nbsp; bioklimatskih&nbsp; analiza&nbsp; na primeru&nbsp; Novog&nbsp; Sada&nbsp; (Srbija).&nbsp; Razvijeni&nbsp; GIS&nbsp; model&nbsp; se&nbsp; pokazao&nbsp; kao&nbsp; adekvatan&nbsp; za mapiranje i definisanje&nbsp; LKZ u Novom Sadu i njegovoj okolini izdvojivši čak 13 LKZ upotrebom 7&nbsp; parametara gradske površine.&nbsp; Osim toga,&nbsp; u&nbsp; okviru disertacije je prikazan i razvijen nov model za čišćenje baze podataka. Dobijeni&nbsp; rezultati&nbsp; su&nbsp; ukazali&nbsp; da&nbsp; se&nbsp; najizraženije&nbsp; razlike&nbsp; u&nbsp; srednjoj temperaturi&nbsp; vazduha&nbsp; (T_sr)&nbsp; javljaju&nbsp; između&nbsp; lokalnih&nbsp; klimatskih&nbsp; zona&nbsp; (LKZ)&nbsp; noću&nbsp; tokom toplotnog talasa i iznose do 5,5 &deg;C (LKZ_2-A, razlika između urbane zbijene srednjegradnje i guste šume izvan grada). Na godišnjem nivou razlike u T_sr iznose 1,7 &deg;C između grada i<br />prirodne&nbsp; okoline,&nbsp; odnosno&nbsp; 0,7&nbsp; &deg;C&nbsp; unutar&nbsp; različitih&nbsp; gradskih&nbsp; LKZ.&nbsp; Statističkom analizom&nbsp; srednjih&nbsp; maksimalnih&nbsp; i&nbsp; apsolutno&nbsp; maksimalnih&nbsp; temperatura&nbsp; vazduha&nbsp; na godišnjem,&nbsp; sezonskom&nbsp; i&nbsp; mesečnom&nbsp; nivou&nbsp; nisu&nbsp; uočene&nbsp; znatne&nbsp; razlike&nbsp; između&nbsp; LKZ. Učestalost&nbsp; pojave&nbsp; temperaturnih&nbsp; indeksa&nbsp; je&nbsp; ukazala&nbsp; da&nbsp; tzv.&nbsp; &bdquo;hladni&nbsp; indeksi&ldquo;&nbsp; (mrazni dani,&nbsp; ledeni&nbsp; dani)&nbsp; ukazuju&nbsp; na&nbsp; temperaturne&nbsp; specifičnosti&nbsp; LKZ&nbsp; u&nbsp; Novom&nbsp; Sadu,&nbsp; dok&nbsp; to nije&nbsp; evidentno&nbsp; analizom&nbsp; tzv.&nbsp; &bdquo;toplih&nbsp; indeksa&ldquo;&nbsp; (letnji&nbsp; dani,&nbsp; tropski&nbsp;&nbsp; dani),&nbsp; izuzev tropskih&nbsp; noći.&nbsp; Analizom&nbsp; relativne&nbsp; vlažnosti&nbsp; vazduha&nbsp; je&nbsp; uočeno&nbsp; da&nbsp; postoje&nbsp; znatne razlike između izgrađenih i prirodnih LKZ, dok to nije slučaj između izg rađenih LKZ. U Novom Sadu se javlja tzv. &bdquo;urbano&nbsp; ostrvo suvoće&ldquo; noću tokom toplotnog talasa kada je zbijena srednjegradnja (LKZ 2)&nbsp; okarakterisana sa maksimalnim deficitom vlažnosti od oko&nbsp; 33%&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; prirodnu&nbsp; LKZ&nbsp; A&nbsp; izvan&nbsp; grada.&nbsp; Statistička&nbsp; analiza&nbsp; vrednosti izračunatih&nbsp; bioklimatskih&nbsp; indeksa&nbsp; PET&nbsp; i&nbsp; UTCI&nbsp; je&nbsp; ukazala&nbsp; da&nbsp; se&nbsp; LKZ&nbsp; razlikuju&nbsp; u&nbsp; uslovima&nbsp; spoljnjeg&nbsp; termalnog&nbsp; komfora&nbsp; čoveka&nbsp; na&nbsp; godišnjem,&nbsp; sezonskom&nbsp; i&nbsp; mesečnom nivou,&nbsp; kao&nbsp; i&nbsp; tokom&nbsp; toplotnog&nbsp; i&nbsp; hladnog&nbsp; talasa&nbsp; (do&nbsp; maksimalnih&nbsp; 8-9&nbsp; &deg;C).&nbsp; Takođe&nbsp; su rezultati ukazali&nbsp; da je klasifikacioni sistem&nbsp; LKZ adekvatan za inter-urbanu analizu gradske klime (poređenja između gradova).</p> / <p>The&nbsp; topic&nbsp; of&nbsp; the&nbsp; doctoral&nbsp; dissertation&nbsp; is&nbsp; the&nbsp; application&nbsp; and&nbsp; assessment&nbsp; of&nbsp; the&nbsp; classification system of local climate zones (LCZ) using the automated model and bioclimatic analysis on the example of Novi Sad (Serbia). The developed GIS model proved to be adequate for&nbsp; mapping and defining LCZs&nbsp; in Novi Sad and its surroundings by&nbsp; delineating&nbsp; 13 LCZs&nbsp; using 7 parameters of the city surface. In addition, in the&nbsp; framework of the dissertation, is&nbsp; developed new&nbsp; model for cleaning the database. The&nbsp; obtained&nbsp; results&nbsp; indicated&nbsp; that&nbsp; the&nbsp; most&nbsp; pronounced&nbsp; differences&nbsp; in&nbsp; mean&nbsp; air temperature (T_sr) occur between LCZs at night during a heat wave and are up to 5.5 &deg; C (LCZ_2-A, the difference between urban compact midrise and dense forests). At annual level, the difference in&nbsp; T_sr&nbsp; is 1.7 &deg;C between the city and the&nbsp; natural environment, and 0.7 &deg;C within different city LCZs. Statistical analysis of mean maximum and absolute maximum air temperatures at&nbsp; annual, seasonal and monthly levels did not show significant differences between&nbsp; LCZs. The frequency of occurrence of temperature indexes indicated that the so-called &quot;cold indices&quot; (cold days, ice days) indicate the temperature specificity of&nbsp; LCZs&nbsp; in Novi&nbsp; Sad, while this is not evident from the&nbsp; analysis&nbsp; of&nbsp; so-called&nbsp; &quot;warm&nbsp; indices&quot;&nbsp; (summer&nbsp; days,&nbsp; tropical&nbsp; days),&nbsp; except&nbsp; for&nbsp; tropical nights.&nbsp; By&nbsp; analyzing&nbsp; the&nbsp; relative&nbsp; humidity&nbsp; of&nbsp; the&nbsp; air&nbsp; it&nbsp; was&nbsp; noticed&nbsp; that&nbsp; there&nbsp; are&nbsp; significant differences between the built-up&nbsp; and natural&nbsp; LCZs, while this is not the case between built-up LCZs. In Novi Sad there is&nbsp; recognized so-called&nbsp; &quot;Urban dryness&nbsp; island&quot; at night during a heat wave period&nbsp; when a compact midrise LCZ 2&nbsp; is characterized with a maximum humidity deficit of about&nbsp; 33% compared to the natural&nbsp; LCZ&nbsp; A outside the city. Statistical analysis of the values of calculated bioclimatic indexes&nbsp; PET and UTCI indicated that&nbsp; LCZs&nbsp; differ in the conditions of the&nbsp; outdoor&nbsp; thermal&nbsp; comfort&nbsp; of&nbsp; population&nbsp; at&nbsp; annual,&nbsp; seasonal&nbsp; and&nbsp; monthly&nbsp; levels&nbsp; as&nbsp; well&nbsp; as during heat and cold waves (up to a maximum of 8-9 &deg; C differences). The results also indicated<br />that&nbsp; the&nbsp; LCZ&nbsp; classification&nbsp; system&nbsp; is&nbsp; adequate&nbsp; for&nbsp; inter-urban&nbsp; analysis&nbsp; of&nbsp; the&nbsp; city&nbsp; climate (comparsions between cities).</p>

Increasing global mean temperature or global warming has the potential to affect the hydrologic cycle. In the 21st century, according to the UN Intergovernmental Panel on Climate Change (IPCC), alterations in the frequency and magnitude of high intensity rainfall events are very likely. Increasing trend of urbanization across the globe is also noticeable, simultaneously. These changes will have a great impact on water infrastructure as well as environment in urban areas. One of the impacts may be the increase in frequency and extent of flooding. India, in the recent years, has witnessed a number of urban floods that have resulted in huge economic losses, an instance being the flooding of Mumbai in July, 2005. To prevent catastrophic damages due to floods, it has become increasingly important to understand the likely changes in extreme rainfall in future, its effect on the urban drainage system, and the measures that can be taken to prevent or reduce the damage due to floods. Reliable estimation of future design rainfall intensity accounting for uncertainties due to climate change is an important research issue. In this context, rainfall intensity-duration-frequency (IDF) relationships are one of the most extensively used hydrologic tools in planning, design and operation of various drainage related infrastructures in urban areas. There is, thus, a need for a study that investigates the potential effects of climate change on IDF relationships. The main aim of the research reported in this thesis is to investigate the effect of climate change on Intensity-Duration-Frequency relationship in an urban area. The rainfall in Bangalore City is used as a case study to demonstrate the applications of the methodologies developed in the research Ahead of studying the future changes, it is essential to investigate the signature of changes in the observed hydrological and climatological data series. Initially, the yearly mean temperature records are studied to find out the signature of global warming. It is observed that the temperature of Bangalore City shows an evidence of warming trend at a statistical confidence level of 99.9 %, and that warming effect is visible in terms of increase of minimum temperature at a rate higher than that of maximum temperature. Interdependence studies between temperature and extreme rainfall reveal that up to a certain range, increase in temperature intensifies short term rainfall intensities at a rate more than the average rainfall. From these two findings, it is clear that short duration rainfall intensities may intensify in the future due to global warming and urban heat island effect. The possible urbanization signatures in the extreme rainfall in terms of intensification in the evening and weekends are also inferred, although inconclusively. The IDF relationships are developed with historical data and changes in the long term daily rainfall extreme characteristics are studied. Multidecedal oscillations in the daily rainfall extreme series are also examined. Further, non-parametric trend analyses of various indices of extreme rainfall are carried out to confirm that there is a trend of increase in extreme rainfall amount and frequency, and therefore it is essential to the study the effects of climate change on the IDF relationships of the Bangalore City. Estimation of future changes in rainfall at hydrological scale generally relies on simulations of future climate provided by Global Climate Models (GCMs). Due to spatial and temporal resolution mismatch, GCM results need to be downscaled to get the information at station scale and at time resolutions necessary in the context of urban flooding. The downscaling of extreme rainfall characteristics in an urban station scale pose the following challenges: (1) downscaling methodology should be efficient enough to simulate rainfall at the tail of rainfall distribution (e.g., annual maximum rainfall), (2) downscaling at hourly or up to a few minutes temporal resolution is required, and (3) various uncertainties such as GCM uncertainties, future scenario uncertainties and uncertainties due to various statistical methodologies need to be addressed. For overcoming the first challenge, a stochastic rainfall generator is developed for spatial downscaling of GCM precipitation flux information to station scale to get the daily annual maximum rainfall series (AMRS). Although Regional Climate Models (RCMs) are meant to simulate precipitation at regional scales, they fail to simulate extreme events accurately. Transfer function based methods and weather typing techniques are also generally inefficient in simulating the extreme events. Due to its stochastic nature, rainfall generator is better suited for extreme event generation. An algorithm for stochastic simulation of rainfall, which simulates both the mean and extreme rainfall satisfactorily, is developed in the thesis and used for future projection of rainfall by perturbing the parameters of the rainfall generator for the future time periods. In this study, instead of using the customary two states (rain/dry) Markov chain, a three state hybrid Markov chain is developed. The three states used in the Markov chain are: dry day, moderate rain day and heavy rain day. The model first decides whether a day is dry or rainy, like the traditional weather generator (WGEN) using two transition probabilities, probabilities of a rain day following a dry day (P01), and a rain day following a rain day (P11). Then, the state of a rain day is further classified as a moderate rain day or a heavy rain day. For this purpose, rainfall above 90th percentile value of the non-zero precipitation distribution is termed as a heavy rain day. The state of a day is assigned based on transition probabilities (probabilities of a rain day following a dry day (P01), and a rain day following a rain day (P11)) and a uniform random number. The rainfall amount is generated by Monte Carlo method for the moderate and heavy rain days separately. Two different gamma distributions are fitted for the moderate and heavy rain days. Segregating the rain days into two different classes improves the process of generation of extreme rainfall. For overcoming the second challenge, i.e. requirement of temporal scales, the daily scale IDF ordinates are disaggregated into hourly and sub-hourly durations. Disaggregating continuous rainfall time series at sub-hourly scale requires continuous rainfall data at a fine scale (15 minute), which is not available for most of the Indian rain gauge stations. Hence, scale invariance properties of extreme rainfall time series over various rainfall durations are investigated through scaling behavior of the non-central moments (NCMs) of generalized extreme value (GEV) distribution. The scale invariance properties of extreme rainfall time series are then used to disaggregate the distributional properties of daily rainfall to hourly and sub-hourly scale. Assuming the scaling relationships as stationary, future sub-hourly and hourly IDF relationships are developed. Uncertainties associated with the climate change impacts arise due to existence of several GCMs developed by different institutes across the globe, climate simulations available for different representative concentration pathway (RCP) scenarios, and the diverse statistical techniques available for downscaling. Downscaled output from a single GCM with a single emission scenario represents only a single trajectory of all possible future climate realizations and cannot be representative of the full extent of climate change. Therefore, a comprehensive assessment of future projections should use the collective information from an ensemble of GCM simulations. In this study, 26 different GCMs and 4 RCP scenarios are taken into account to come up with a range of IDF curves at different future time periods. Reliability ensemble averaging (REA) method is used for obtaining weighted average from the ensemble of projections. Scenario uncertainty is not addressed in this study. Two different downscaling techniques (viz., delta change and stochastic rainfall generator) are used to assess the uncertainty due to downscaling techniques. From the results, it can be concluded that the delta change method under-estimated the extreme rainfall compared to the rainfall generator approach. This study also confirms that the delta change method is not suitable for impact studies related to changes in extreme events, similar to some earlier studies. Thus, mean IDF relationships for three different future extreme events, similar to some earlier studies. Thus, mean IDF relationships for three different future periods and four RCP scenarios are simulated using rainfall generator, scaling GEV method, and REA method. The results suggest that the shorter duration rainfall will invigorate more due to climate change. The change is likely to be in the range of 20% to 80%, in the rainfall intensities across all durations. Finally, future projected rainfall intensities are used to investigate the possible impact of climate change in the existing drainage system of the Challaghatta valley in the Bangalore City by running the Storm Water Management Model (SWMM) for historical period, and the best and the worst case scenario for three future time period of 2021–2050, 2051–2080 and 2071–2100. The results indicate that the existing drainage is inadequate for current condition as well as for future scenarios. The number of nodes flooded will increase as the time period increases, and a huge change in runoff volume is projected. The modifications of the drainage system are suggested by providing storage pond for storing the excess high speed runoff in order to restrict the width of the drain The main research contribution of this thesis thus comes from an analysis of trends of extreme rainfall in an urban area followed by projecting changes in the IDF relationships under climate change scenarios and quantifying uncertainties in the projections.

Städte sind Hotspots des Globalen Wandels. Sie zählen über ihren Konsum und Ressourcenverbrauch zu den Haupttreibern des Klimawandels, der Biodiversitätskrise und sozio-ökonomischer Prozesse wie Urbanisierung und Demographischer Wandel. Gleichzeitig stellen diese Prozesse insbesondere für Städte eine große Herausforderung dar. Für die Anpassung an den Globalen Wandel spielen städtische Grünflächen als Werkzeug der Stadtplanung eine zentrale Rolle. Parks, Friedhöfe, Gärten, bis hin zu einzelnen Straßenbäumen stellen Ökosystemleistungen bereit, die einerseits, z.B. durch Abmilderung von hohen Temperaturen, die Umweltqualität verbessern und andererseits, z.B. durch die Bereitstellung von Erholungsräumen, einen direkten Einfluss auf das Wohlbefinden und die Aktivitäten der Stadtbevölkerung haben. Jedoch sind auch Grünflächen und deren Ökosystemleistungen, wie die gesamte Stadt an sich, hohen Belastungen durch die Folgen des Globalen Wandels ausgesetzt, z.B. durch Hitze, Trockenheit und Verdichtungsprozesse. Diese kumulative Dissertation zeigt, dass sich Form, Ausstattung und Lage einer Grünfläche unterschiedlich auf die Bereitstellung von verschiedenen Ökosystemleistungen auswirken. Während für die Kühlungsfunktion ein dichter Bestand von ausgewachsenen Bäumen entscheidend ist, spielt für die Erholungsfunktion einer Grünfläche eine ausgewogene Vegetationsstruktur, vielfältige (gebaute) Infrastruktur und eine gute Einbettung in die Umgebung eine zentrale Rolle. Die Arbeit formuliert schließlich Empfehlungen an die Stadtplanung für eine qualitative Aufwertung der Grünflächen im Hinblick auf eine bessere und gerechte Versorgung der Bevölkerung und eine größere Widerstandsfähigkeit gegenüber extremen Wetterereignissen. Eine im Rahmen dieser Arbeit entwickelte und frei zugängliche Online-Kartenanwendung kann dabei als ein unterstützendes Entscheidungsinstrument dienen und zukünftig auf andere Städte übertragen werden. / Cities are hotspots of global change. Through their consumption and resource use, cities are among the main drivers of climate change, the biodiversity crisis and socio-economic processes such as urbanisation and demographic change. At the same time, these processes represent a major challenge for cities. Extreme weather events caused by climate change, such as heat and heavy rain, often occur with greater intensity in densely populated areas and can potentially cause more damage to people and infrastructure there. For adaptation to global change, urban green spaces play a central role as a tool in urban planning. Green spaces or individual street trees provide ecosystem services that can improve, on the one hand, environmental quality, e.g. by mitigating high air temperatures, and, on the other hand, the health and well-being of the urban population, e.g. through the provision of recreational opportunities. However, green spaces and their ecosystem services are also exposed to high pressures from the impacts of global change such as extreme heat, drought and densification processes. This cumulative thesis shows that the form, equipment and location of a green space have different effects on the provision of different ecosystem services. While a dense stand of mature trees is crucial for the cooling function, a balanced vegetation structure, diverse (built) infrastructure and a good embedding in the surroundings play a central role for the recreational function of a green space. Finally, the thesis formulates recommendations for urban planning for a qualitative upgrading of green spaces with regard to a better and equitable provision for the population and a greater resilience to extreme weather events. An open access online map application developed as part of this thesis is intended to serve as a decision support tool and may be transferred to other case studies in the future.