劇烈的城市化過程已經在世界上多個地區發生並產生了許多的城市群，珠江三角洲正是這樣的一個城市群。目前，珠江三角洲上的城市土地利用和土地覆蓋已經發生了巨大的變化。而其中最重要的一個結果就是大量城市不透水層的出現，並已經極大地影響著當地的城市環境，如城市洪水、城市氣候、水污染和大氣污染等。因此，城市不透水層及其分佈的估算對於監測和管理城市化進程及其對環境的影響有著重要的意義。然而，由於城市土地覆蓋類型的多樣性，精確的城市不透水層的估算（ISE）仍然是一個極具挑戰性的課題。本論文旨在通過融合光學遙感和合成孔徑雷達（SAR）遙感技術來提高亞熱帶濕潤區城市不透水層估算的精度。此外，論文還將探索亞熱帶濕潤區土地覆蓋類型分類的季節性變化及其對城市不透水層提取的影響。本論文的研究結果主要包括以下幾個部分。 / 首先，本研究發現亞熱帶濕潤區不透水層提取的季節性效應與中緯度地區截然不同。在亞熱帶濕潤地區，冬季是最適合用遙感影像進行不透水層提取的。原因是由於冬季是旱季，雲量少，許多可變來源區域（VSA）沒有水體覆蓋，而在遙感影像中，水體容易和暗不透水層混淆。另一方面，秋季最不適合不透水層提取，因為存在大量的雲層，並且，大量的降水導致VSA區域充滿水，從而增加了與暗不透水層混淆的區域面積。此外，大量的雲層在影像中也是呈現高反射特徵的，因此極容易和亮不透水層混淆，這是秋季不適合用於提取不透水層的另一重要原因。 / 其次，提出了一種新的基於形狀自我調整鄰域（SAN）的特徵提取演算法。該特徵提取演算法類比人類視覺對圖像感知的強大能力，進行遙感影像低層特徵的提取。實驗結果表明，SAN特徵提取方法對非監督分類有顯著的提高，其中總體分類精度從0.58提高到0.86，而Kappa係數從0.45提高到0.80。SAN特徵對於監督分類的精度也有一定的提高，這些都表明，與傳統的特徵提取方法相比，SAN特徵對遙感影像分類具有重要的作用。 / 再次，通過對比分析光學遙感影像和SAR影像發現，單獨採用光學遙感影像進行不透水層提取比單獨採用SAR影像取得更好的結果。同時，單獨採用光學遙感（Landsat ETM+）時，支援向量機（SVM）比人工神經網路（ANN）取得更好的結果，這是因為ANN對於亮不透水層與幹裸土之間，以及暗不透水層與陰影之間的光譜混淆更加敏感。然而，當單獨採用SAR遙感（ENVISAT ASAR）時，ANN則取得更好的結果，這是由於SVM分析SAR影像時更容易產生雜訊，並具有明顯的邊緣效應。因此，融合光學遙感和SAR遙感具有重要的意義。通過比較不同圖像融合層次發現，像元級融合（Pixel Level Fusion）會降低單獨採用光學遙感提取不透水層的精度，因而不適合光學和SAR影像的融合。而特徵級融合（Feature Level）決策級融合（Decision Level）可以更好的把不透水層從陰影區域和裸土中區分出來，因為更加適合光學與SAR的融合。 / 最後，三組不同的光學遙感和SAR遙感影像被用於評估本論文提出的光學和SAR融合方法，包括Landsat ETM+與ASAR影像，SPOT-5與ASAR影像，以及SPOT-5與TerraSAR-X影像。此外，還比較了不同的融合方法（人工神經網路、支援向量機和隨機森林）對融合結果的影響。結果表明，用光學和SAR遙感影像融合提取不透水層有利於減少在光學遙感影像中容易出現的光譜混淆現象，從而提高不透水層提取的精度。另外，隨機森林在融合光學和SAR影像中效果較其它兩種方法，因為隨機森林對兩種不同的資料來源區別對待，而這正是符合光學遙感與SAR遙感截然不同的工作方式的特點，從而能更好的融合光學遙感和SAR遙感。 / 本論文的研究成果有助於探索亞熱帶濕潤區中物候特點和氣候特點對城市不透水層提取所產生的季節性效應；同時也為融合光學遙感和SAR遙感影像提取城市不透水層提供了一個技術框架。由於珠江三角洲是一個亞熱帶濕潤區一個典型的快速城市化的城市群區域，本文所提出的方法框架和所得到研究結論可為世界上其它亞熱帶濕潤區的城市遙感研究提供一定的參考價值。 / Dramatic urbanization processes have happened in many regions and thus created a number of metropolises in the world. The Pearl River Delta (PRD) is one of such typical areas, where the urban land use/land cover has been significantly changing in the recent past. As one of the most important implications, a large increment of impervious surface (IS) turned out to be one of the features of fast urbanization process and has been influencing the urban environment significantly, including urban flooding, urban climate, water pollutions, and air pollutions. Therefore, the estimation of IS would be very helpful to monitor and manage the urbanization process and its impacts on the environment. However, accurate estimation of urban IS remains challenging due to the diversity of land covers. This dissertation attempts to fuse optical and SAR remote sensing data to improve the accuracy of urban impervious surface estimation (ISE) in humid subtropical regions (HSR). The seasonal characteristics of land covers and its impacts on ISE in HSR are all investigated. Some interesting findings are summarized as follows. / Firstly, the study demonstrates quite a special pattern of the seasonal effects of ISE in humid subtropical areas that is different from that in mid-latitude areas. According to the results, in subtropical monsoon regions, winter is the best season to estimate IS from satellite images. There are little clouds, and most of the Variable Source Areas (VSA) is not filled with water. On the other hand, autumn images obtained the lowest accuracy of IS due to the clouds coverage and the water in VSA. Autumn is a rainy season in a subtropical monsoon region, for which clouds occur very often and VSA areas are always filled with water. Consequently, clouds are confused with bright IS due to their similarly high reflectance, and more water in VSA is confused with dark IS due to their similarly low reflectance. / Secondly, a novel feature extraction technique, based on the shape-adaptive neighborhood (SAN), is proposed to incorporate the advantages of human vision into the process of remote sensing images. Quantitative results showed that improvement of SAN features is particularly significant improvement for the unsupervised classifier, for which the overall accuracy increased from 0.58 to 0.86, and the Kappa coefficient increased from 0.45 to 0.80, indicating promising applications of SAN features in the unsupervised processing of remote sensing images. / Thirdly, a comparison study of ISE between optical and SAR image demonstrates that single optical image provides better results than using single SAR image. In addition, results indicate that support vector machine (SVM) is a better choice for ISE using Landsat ETM+ (optical) images, while artificial neural network (ANN) turns out to be more sensitive to the confusion between dry soils and bright IS, and between shades and dark IS. However, ANN gets a better result using ASAR (SAR) image with higher accuracy, while the SVM classifier produces more noises and has some edge effects. Considering both the merits and demerits of optical and SAR images, synergistically fusing the two data sources should be a promising solution. Comparison of three different levels of fusion shows that pixel level fusion seems not appropriate for optical-SAR fusion, as it reduces the accuracy compared to the single use of optical data. Meanwhile, feature level fusion and decision level fusion obtained better accuracy, since they improves the identification of IS from shaded areas and bare soils. / Fourthly, a methodological framework of fusing the optical and SAR images is proposed. Three different data sets are used to assess the effectiveness of this methodological framework, including the Landsat TM and ASAR images, the SPOT-5 and ASAR images, and the SPOT-5 and TerraSAR-X images. In addition, different methods (e.g. ANN, SVM and Random Forest) are employed and compared to fusion the two data sources at a mixed level fusion of pixel and feature levels. Experimental results showed that the combined use of optical and SAR image is able to effectively improve the accuracy of ISE by reducing the spectral confusions that happen easily in optical images. Moreover, Random Forest (RF) demonstrated a promising performance for fusing optical and SAR images as it treats the two data sources differently through a random selection procedure of variables from different data sources. / The major outcome of this research provides evidence of the seasonal effects on IS assessment due to phenological and climatic characteristics, as well as provides an applicable framework of methodology for the synergistic use of optical and SAR images to improve the ISE. Since the PRD region is highly typical of many fast growing areas, the methodology and conclusions of this research would serve as a useful reference for other subtropical, humid regions of the world. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhang, Hongsheng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 169-185). / Abstract also in Chinese. / ACKNOWLEDGEMENTS --- p.i / ABSTRACT --- p.iii / 論文摘要 --- p.vii / Table of Contents --- p.xi / List of Abbreviations --- p.xv / List of Tables --- p.xvii / List of Figures --- p.xviii / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Research background --- p.1 / Chapter 1.2 --- Research questions and hypotheses --- p.4 / Chapter 1.3 --- Objectives and significance --- p.6 / Chapter 1.4 --- Organization of the thesis --- p.7 / Chapter CHAPTER 2 --- LITERATURE REVIEW --- p.11 / Chapter 2.1 --- Introduction --- p.11 / Chapter 2.2 --- Significance of Impervious Surface --- p.12 / Chapter 2.2.1 --- Environmental significance --- p.12 / Chapter 2.2.2 --- Socio-economic significance --- p.16 / Chapter 2.3 --- Climatology and Phenology in HSR --- p.18 / Chapter 2.3.1 --- Characteristics of the climate and phenology --- p.18 / Chapter 2.3.2 --- Seasonal effects from Climatology and Phenology --- p.20 / Chapter 2.4 --- Land-cover complexity in rapid urbanized region --- p.21 / Chapter 2.5 --- Approaches of ISE --- p.22 / Chapter 2.5.1 --- Sub-pixel approaches --- p.22 / Chapter 2.5.2 --- Per-pixel approaches --- p.23 / Chapter 2.5.3 --- Synergistic use of optical and SAR data for ISE --- p.27 / Chapter 2.6 --- Summary --- p.28 / Chapter CHAPTER 3 --- STUDY AREA AND DATA SETS --- p.31 / Chapter 3.1 --- Study area --- p.31 / Chapter 3.1.1 --- Site A: Guangzhou --- p.32 / Chapter 3.1.2 --- Site B: Shenzhen --- p.33 / Chapter 3.1.3 --- Site C: Hong Kong --- p.34 / Chapter 3.2 --- Satellite data --- p.35 / Chapter 3.2.1 --- Landsat ETM+ --- p.35 / Chapter 3.2.2 --- SPOT-5 --- p.36 / Chapter 3.2.3 --- ENVISAT ASAR --- p.36 / Chapter 3.2.4 --- TerraSAR-X --- p.37 / Chapter 3.3 --- Digital Orthophoto data --- p.38 / Chapter 3.4 --- In-situ data --- p.39 / Chapter 3.5 --- Summary --- p.40 / Chapter CHAPTER 4 --- METHODOLOGY --- p.43 / Chapter 4.1 --- Framework --- p.43 / Chapter 4.2 --- Per-pixel modeling of ISE --- p.45 / Chapter 4.3 --- Investigation of the seasonal effects --- p.46 / Chapter 4.4 --- Feature extraction --- p.47 / Chapter 4.4.1 --- Conventional approach --- p.48 / Chapter 4.4.2 --- Novel approach based on shape-adaptive neighborhood --- p.48 / Chapter 4.4.2.1 --- The concept of shape-adaptive neighborhood --- p.49 / Chapter 4.4.2.2 --- The determination of a shape-adaptive neighborhood --- p.51 / Chapter 4.4.2.3 --- Extracting spatial features --- p.54 / Chapter 4.5 --- Fusing the optical and SAR data --- p.58 / Chapter 4.5.1 --- Multi-source image co-registration --- p.60 / Chapter 4.5.2 --- Compare the single use of optical and SAR image --- p.61 / Chapter 4.5.3 --- Compare different levels of fusion --- p.62 / Chapter 4.5.4 --- Fusion with supervised classifiers --- p.65 / Chapter 4.5.4.1 --- Artificial neural network --- p.66 / Chapter 4.5.4.2 --- Support vector machine --- p.68 / Chapter 4.5.4.3 --- Random Forest --- p.71 / Chapter 4.6 --- Results validation and accuracy assessment --- p.75 / Chapter 4.6.1 --- Training and testing data sampling --- p.75 / Chapter 4.6.2 --- Accuracy assessment --- p.76 / Chapter 4.7 --- Summary --- p.77 / Chapter CHAPTER 5 --- RESULTS AND DISCUSSION (I) - ASSESSMENT OF SAN FEATURES --- p.79 / Chapter 5.1. --- Analysis of threshold to determine the SAN --- p.79 / Chapter 5.2. --- Feature extraction from SAN --- p.80 / Chapter 5.3. --- Assessment of the SAN features with classification --- p.82 / Chapter 5.3.1 --- Training samples and classification --- p.82 / Chapter 5.3.2 --- Testing samples and accuracy --- p.84 / Chapter 5.3.3 --- Assess the effectiveness of the SAN based features --- p.85 / Chapter 5.4 --- Summary --- p.87 / Chapter CHAPTER 6 --- RESULTS AND DISCUSSION (II) - SEASONAL EFFECTS OF ISE --- p.89 / Chapter 6.1 --- Seasonal effects of ISE --- p.89 / Chapter 6.2 --- Analyzing the seasonal changes of typical targets --- p.92 / Chapter 6.3 --- Comparing the seasonal sensitivity of methods --- p.96 / Chapter 6.4 --- Summary --- p.97 / Chapter CHAPTER 7 --- RESULTS AND DISCUSSION (III) - URBAN LAND COVER DIVERSITY --- p.101 / Chapter 7.1 --- Introduction --- p.101 / Chapter 7.2 --- Urban LC classification Using RF --- p.102 / Chapter 7.2.1 --- Optimization of RF --- p.102 / Chapter 7.2.2 --- Land covers classification with optimized RF --- p.104 / Chapter 7.2.3 --- Compare RF with other decision tree-based methods --- p.107 / Chapter 7.3 --- Summary --- p.108 / Chapter CHAPTER 8 --- RESULTS AND DISCUSSION (IV) - FUSING OPTICAL&SAR DATA --- p.111 / Chapter 8.1 --- Introduction --- p.111 / Chapter 8.2 --- Comparison of ISE with single optical and SAR data --- p.111 / Chapter 8.2.1 --- ISE with ETM+ data --- p.112 / Chapter 8.2.1.1 --- Mapping the IS --- p.112 / Chapter 8.2.1.2 --- Effects of the parameter configurations of the methods --- p.114 / Chapter 8.2.2 --- ISE with ASAR data --- p.115 / Chapter 8.2.2.1 --- Mapping the IS --- p.115 / Chapter 8.2.2.2 --- Effects of the parameter configurations of the methods --- p.117 / Chapter 8.2.3 --- Comparisons over the data and methods --- p.119 / Chapter 8.2.4 --- Discussion and implications --- p.121 / Chapter 8.3 --- Comparison of different levels of fusion method --- p.122 / Chapter 8.3.1 --- Fusion strategies at different levels --- p.122 / Chapter 8.3.2 --- Results of feature extractions --- p.124 / Chapter 8.3.3 --- Fusion results on different levels --- p.126 / Chapter 8.3.4 --- Comparisons --- p.128 / Chapter 8.3.5 --- Discussion and implications --- p.129 / Chapter 8.4 --- Synergizing optical and SAR data with RF --- p.130 / Chapter 8.4.1 --- Feature extraction from ASAR data --- p.130 / Chapter 8.4.2 --- Determine the optimal number of features in each decision tree --- p.132 / Chapter 8.4.3 --- Determine the optimal numbers of decision trees in the RF --- p.134 / Chapter 8.4.4 --- ISE with optimized RF --- p.135 / Chapter 8.4.5 --- Discussion and implications --- p.140 / Chapter 8.5 --- A comprehensive study: ISE using SPOT-5 and TerraSAR-X data --- p.142 / Chapter 8.5.1 --- Data set and experiment design --- p.142 / Chapter 8.5.2 --- Feature extraction of SPOT-5 data --- p.145 / Chapter 8.5.3 --- Feature extraction of TerraSAR-X data --- p.148 / Chapter 8.5.4 --- LULC classification with optimized models --- p.149 / Chapter 8.5.5 --- ISE with optimized models --- p.152 / Chapter 8.5.6 --- Discussion and implications --- p.155 / Chapter 8.6 --- Summary --- p.156 / Chapter CHAPTER 9 --- CONCLUSIONS --- p.159 / Chapter 9.1 --- Findings and conclusions --- p.159 / Chapter 9.1.1 --- Seasonal effects of ISE in HSR --- p.159 / Chapter 9.1.2 --- Feature extraction methods --- p.160 / Chapter 9.1.3 --- Comparison between optical and SAR data --- p.161 / Chapter 9.1.4 --- Fusion level and fusion methods --- p.162 / Chapter 9.2 --- Recommendations for future research --- p.163 / Chapter 9.2.1 --- Feature extraction --- p.163 / Chapter 9.2.2 --- Study areas selection and design --- p.163 / Chapter 9.2.3 --- Validation with in-situ data --- p.164 / Chapter 9.2.4 --- Fusion level and strategy --- p.164 / Chapter 9.2.5 --- Fusion methods --- p.165 / References --- p.169 / Chapter Appendix I --- Codes for Determining Shape-adaptive Neighborhood --- p.186 / Chapter Appendix II --- Publication list related to this thesis research --- p.188

Les multifractals universels (UM) sont un outil puissant et abondement utilisé d'analyse et de simulation de champs géophysiques, comme la pluie, extrêmement variables sur une large gamme d'échelle. Ils sont basés sur le concept de cascade multiplicative qui repose sur la notion physique d'invariance d'échelle pour explorer le phénomène fondamental qu'est l'intermittence. Dans ce cadre, toute la variabilité du champ est caractérisée à l'aide de simplement trois paramètres qui ont en plus une interprétation physique. Dans cette thèse on utilise ce cadre théorique pour quantifier l'impact de la variabilité à petite échelle de la pluie en hydrologie urbaine. La première étape consiste à analyser la variabilité spatio-temporelle de données radar de précipitation à l'aide d'un modèle multifractal anisotrope simple. Divers évènements pluvieux sont analysés. Un comportement scalant a été observé sur deux gammes d'échelles séparées par une rupture à 16 km qui est discutée. Ces données sont globalement en accord avec un modèle spatio-temporel simple reposant un exposant d'anisotropie entre l'espace et de temps. Les résultats suggèrent une possible universalité des paramètres UM pour les précipitations. Cette thèse aborde également un autre aspect de l'intermittence, particulièrement important pour les longues séries temporelles pluviométriques, que sont les nombreuses mesures nulles de la pluie (c'est-à-dire un pixel où aucune pluie n'est relevée), i.e. les longues périodes sèches. L'ancienne question de la source de cette intermittence, et notamment la nécessité d'un modèle dédié, est revisitée. D'abord les effets d'un seuil sur un champ multifractal sont analysés et ensuite un « toy model » qui introduit des zéros au sein du processus de cascade et conditionnellement aux valeurs du champ est développé. Cela permet d'expliquer la plupart des comportements observés, e.g. les différences entre les statistiques évènementielles et globales. L'impact de la variabilité de la pluie est analysé à travers l'étude de la sensibilité de modèles d'hydrologie/hydraulique urbaine à la donnée de pluie. Deux bassins versants essentiellement urbains (un de 3 400 ha en Seine-Saint-Denis à proximité de Paris, et un de 900 ha à Londres) modélisés avec des modèles opérationnels semi-distribués sont pris comme cas d'études. Par ailleurs le modèle distribué Multi-Hydro (en développement au LEESU) est testé sur une portion de 145 ha du cas d'étude parisien. L'impact de la variabilité à petites échelles non mesurée des précipitations (i.e. se produisant à des échelles plus petites que 1 km en espace et 5 min en temps qui sont disponibles avec les données radar à bande C) est d'abord évalué. Ceci est réalisé par la génération d'un ensemble de pluie réaliste désagrégée en continuant stochastiquement le processus sous-jacent de cascade au-delà de l'échelle d'observation, puis la simulation de l'ensemble correspondant d'hydrographes. Il apparaît que la variabilité à petites échelles de la pluie engendre une variabilité hydrologique qui ne doit pas être négligée. De plus le modèle Multi-Hydro génère une variabilité plus importante et pas seulement au niveau du pic de débit, i.e. même pour les pluies modérées. Ces résultats mettent en lumière la nécessité d'installer des radars en bande X (dont la résolution est hectométrique) en milieu urbain. Dans un deuxième temps les outils multifractals sont employés sur les pluies et les débits simulés qui présentent aussi un comportement scalant. Il apparaît que le réseau d'assainissement transmet simplement la variabilité des précipitations sans l'atténuer, au moins en termes de statistiques multifractals / The Universal Multifractals (UM) are a powerful tool which has been extensively used to analyze and simulate geophysical fields, such as rainfall, that are extremely variable over wide range of scales. It is based on the concept of cascade phenomenology that relies on the physical notion of scale invariance to explore the fundamental phenomenon of intermittency. In this framework the whole variability of a field is characterized with the help of only three parameters that are furthermore physically meaningful. In this PhD thesis we use this theoretical framework to quantify the impacts of small scale rainfall variability in urban hydrology. The first step consists in analysing radar rainfall space-time variability with the help of a simple anisotropic multifractal model. A variety of rainfall events are analyzed. It appears that a scaling behaviour was observed on two distinct ranges of scales separated by a break at roughly 16 km that is discussed. These data sets are in overall agreement with a simple space-time scaling model relying on single anisotropy exponent between space and time. The results hint at a possible universality of the UM parameters for rainfall. This thesis also explores another facet of intermittency, which is particularly important for long time series of precipitation, that of numerous zero rainfall measurements (a pixel or a time step with no recorded rainfall), i. e. long “dry” periods. We revisit the long lasting discussion on the source of this intermittency, e.g. whether it requires a specific modelling. First the effects of a threshold on a universal multifractal field are investigated and second a toy model that introduces some zeros within the cascade process conditioned by the field value is developed. This enables to explain most of the observed behaviour, e.g. the difference between event statistics and overall statistics. The impact of rainfall variability is investigated through the analysis of the sensitivity to the rainfall input of urban hydrologic-hydraulic models. Two predominantly urban catchments (a 3 400 ha one in Seine-Saint-Denis near Paris, and a 900 ha one in London) modelled with the help of operational semi-distributed models are used as case studies. The fully distributed model Multi-Hydro (under development at LEESU) is also tested on a 147 ha portion of the Paris case study. First the impact of unmeasured small scale rainfall variability (i.e. occurring at scales smaller than 1 km in space and 5 min in time which are available with C-band radar data) is evaluated. This is achieved by generating an ensemble of realistic downscaled rainfall fields by continuing the stochastic cascade process below the observation scale and then simulating the corresponding ensemble of hydrographs. It appears that the small scale rainfall variability generates significant hydrological variability that should not be neglected. Furthermore the Multi-Hydro model generates a larger variability not only during the peak flow, but during the whole event, i.e. for moderate rain rates. These findings highlight the need to implement X-band radars (whose resolution is hectometric) in urban areas. In a second part multifractal tools are used on both rainfall and simulated discharges that also exhibit a scaling behaviour. It appears that the rainfall drainage system basically transmits the rainfall variability without damping it, at least in terms of multifractal statistics

A urbanização acelerada e mal planejada pode ocasionar diversas alterações e consequências para o ambiente, como a sistemática impermeabilização do solo, que pode ocasionar aumento do escoamento superficial da água e redução do tempo de escoamento, gerando problemas como enchentes, alagamentos, aumento do risco de desastres naturais, entre outros. A criação de mais áreas verdes pode ser considerada uma alternativa adequada para reduzir esses fenômenos, frente à rápida e crescente expansão urbana. Como os benefícios hidrológicos das árvores em ambiente urbano ainda são pouco explorados por pesquisadores, sobretudo no Brasil, existe a necessidade de se determinar o quanto a cobertura arbórea é capaz de influenciar na redução das consequências de eventos extremos para os ambientes urbanos. O i-Tree Hydro é um programa pioneiro em relacionar explicitamente os efeitos das árvores nas águas pluviais em área urbana, fornecendo diretrizes para o planejamento do espaço em áreas sensíveis à fenômenos ambientais. Portanto, este trabalho pretende aplicou o programa em uma bacia hidrográfica da cidade de São Paulo, com o objetivo de melhor compreender como a disposição das árvores podem influenciar em uma área densamente urbanizada. Foi possível concluir utilizando o programa i-Tree Hydro que se aumentamos a cobertura arbórea e diminuímos a impermeabilização da bacia a uma queda de 12% na vazão média anual. Enquanto, fazendo o processo oposto e aumentando a impermeabilização e diminuindo a cobertura arbórea o volume médio anual da bacia aumenta cerca de 6%. Também foi possível concluir neste trabalho que apenas aumentando a cobertura arbórea da bacia de estudo sem alterar a impermeabilização é possível uma redução de 4% na vazão média anual da bacia e que a remoção de toda cobertura arbórea da mesma provoca um aumento de cerca de 21% , aumentando a média anual em aproximadamente 700 m³. / Accelerated and poorly planned urbanization can cause a number of changes and consequences for the environment, such as systematic soil sealing, which can lead to increased water runoff and reduced run-off time, generating problems such as flooding, flooding, natural disasters, among others. The creation of more green areas can be considered an adequate alternative to reduce these phenomena, in front of the rapid and increasing urban expansion. As the hydrological benefits of trees in urban environments are still little explored by researchers, especially in Brazil, there is a need to determine how much tree cover is capable of influencing the reduction of the consequences of extreme events for urban environments. The i-Tree Hydro is a pioneering program to explicitly relate the effects of trees to rainwater in urban areas, providing guidelines for space planning in areas sensitive to environmental phenomena. Therefore, this work intends to apply the program in a river basin of the city of São Paulo, in order to better understand how the use of permeable pavements and the quantity and arrangement of trees can influence in a densely urbanized area. It was possible to conclude by using the i-Tree Hydro program that we increased the tree cover and decreased the waterproofing of the basin to a fall of 12% in the average annual flow. Meanwhile, by doing the opposite process and increasing waterproofing and decreasing tree cover the average annual volume of the basin increases by about 6%. It was also possible to conclude in this work that only increasing the tree cover of the study basin without altering the waterproofing is possible a reduction of 4% in the average annual flow of the basin and that the removal of all the tree cover of the same causes an increase of about 21 %, increasing the annual average by approximately 700 m³.

A urbanização acelerada e mal planejada pode ocasionar diversas alterações e consequências para o ambiente, como a sistemática impermeabilização do solo, que pode ocasionar aumento do escoamento superficial da água e redução do tempo de escoamento, gerando problemas como enchentes, alagamentos, aumento do risco de desastres naturais, entre outros. A criação de mais áreas verdes pode ser considerada uma alternativa adequada para reduzir esses fenômenos, frente à rápida e crescente expansão urbana. Como os benefícios hidrológicos das árvores em ambiente urbano ainda são pouco explorados por pesquisadores, sobretudo no Brasil, existe a necessidade de se determinar o quanto a cobertura arbórea é capaz de influenciar na redução das consequências de eventos extremos para os ambientes urbanos. O i-Tree Hydro é um programa pioneiro em relacionar explicitamente os efeitos das árvores nas águas pluviais em área urbana, fornecendo diretrizes para o planejamento do espaço em áreas sensíveis à fenômenos ambientais. Portanto, este trabalho pretende aplicou o programa em uma bacia hidrográfica da cidade de São Paulo, com o objetivo de melhor compreender como a disposição das árvores podem influenciar em uma área densamente urbanizada. Foi possível concluir utilizando o programa i-Tree Hydro que se aumentamos a cobertura arbórea e diminuímos a impermeabilização da bacia a uma queda de 12% na vazão média anual. Enquanto, fazendo o processo oposto e aumentando a impermeabilização e diminuindo a cobertura arbórea o volume médio anual da bacia aumenta cerca de 6%. Também foi possível concluir neste trabalho que apenas aumentando a cobertura arbórea da bacia de estudo sem alterar a impermeabilização é possível uma redução de 4% na vazão média anual da bacia e que a remoção de toda cobertura arbórea da mesma provoca um aumento de cerca de 21% , aumentando a média anual em aproximadamente 700 m³. / Accelerated and poorly planned urbanization can cause a number of changes and consequences for the environment, such as systematic soil sealing, which can lead to increased water runoff and reduced run-off time, generating problems such as flooding, flooding, natural disasters, among others. The creation of more green areas can be considered an adequate alternative to reduce these phenomena, in front of the rapid and increasing urban expansion. As the hydrological benefits of trees in urban environments are still little explored by researchers, especially in Brazil, there is a need to determine how much tree cover is capable of influencing the reduction of the consequences of extreme events for urban environments. The i-Tree Hydro is a pioneering program to explicitly relate the effects of trees to rainwater in urban areas, providing guidelines for space planning in areas sensitive to environmental phenomena. Therefore, this work intends to apply the program in a river basin of the city of São Paulo, in order to better understand how the use of permeable pavements and the quantity and arrangement of trees can influence in a densely urbanized area. It was possible to conclude by using the i-Tree Hydro program that we increased the tree cover and decreased the waterproofing of the basin to a fall of 12% in the average annual flow. Meanwhile, by doing the opposite process and increasing waterproofing and decreasing tree cover the average annual volume of the basin increases by about 6%. It was also possible to conclude in this work that only increasing the tree cover of the study basin without altering the waterproofing is possible a reduction of 4% in the average annual flow of the basin and that the removal of all the tree cover of the same causes an increase of about 21 %, increasing the annual average by approximately 700 m³.

Les travaux décrits dans le présent rapport concernent l’étude d’un ouvrage de traitement en ligne des eaux pluviales issues d’un bassin versant fortement urbanisé. L’ouvrage Charles Keller, d’une capacité de 7000 m3, est conçu pour traiter les eaux pluviales issues du bassin versant de Boudonville, situé dans la Communauté Urbaine du Grand Nancy. L’ouvrage est installé à l’exutoire de bassin versant en aval d’autres ouvrages de stockage temporaires. Les eaux traitées par l’ouvrage Charles Keller sont ensuite renvoyées vers la Meurthe et les boues produites sont traitées au niveau de la station d’épuration du Grand Nancy à Maxéville. La stratégie adoptée dans ce travail a permis de d’aborder l’ouvrage sous plusieurs angles : 1) d’abord l’étude de l’ouvrage seul en se focalisant sur l’ensemble de ses composantes unitaires (dessableurs, chambre d’injection des réactifs, réacteurs et décanteurs) ; 2) la partie physico-chimique (non opérationnelle jusqu’à présent) a fait l’objet de plusieurs compagnes d’analyse à travers les essais en Jar test effectués au laboratoire sur des eaux issues du bassin versant de Boudonville dont les caractéristiques couvrent toute la gamme que l’ouvrage Charles Keller peut traiter ; 3) ensuite l’ouvrage a été resitué dans l’ensemble du système de gestion des eaux pluviales (bassin versant - ouvrage Charles Keller - station d’épuration) et son fonctionnement simulé. Plusieurs configurations ont été testées pour reproduire les conditions réelles de fonctionnement de l’ouvrage. Les résultats obtenus ont montré d’abord la complexité de faire fonctionner dans la pratique un tel ouvrage, notamment avec sa partie coagulation/floculation mais a fait également ressortir des défauts de conception. / An online urban storm-water treatment system has been studied in this work. This system is able to treat the runoff from a highly impervious watershed (Boudonville) in Greater Nancy (North-East of France). It has a capacity of 7000 cubic meters. Some storage tanks are existing in the watershed. The treated water is discharged into the Meurthe River, while the sludge is treated in the Greater Nancy wastewater treatment plant in Maxéville.The strategy adopted in this work allowed for the consideration of the treat ment system from several angles:• first of all, the system is analyzed through its elementary components (sand removal unit, reagents injection and reactors for flocculation-coagulation and clarifiers): this has been done by observing the variations in water quality at the different treatment levels with online instrumentation. This has been completed with an offline characterization.• the flocculation-coagulation section, which was not yet operational during our work, was studied in the laboratory by jar tests. The water to be treated was sampled from the Boudonville watershed to be close to the conditions that should be observed in the Charles Keller treatment system.• finally the stormwater treatment was simulated as part of a full storm-water management system (watershed-Charles Keller treatment system-wastewater treatment plant).• The results that were obtained showed in the one hand the complexity of using such a treatment system in real-life conditions, especially with a coagulation / flocculation part to it, which has some conceptual issues.

La gestion des eaux pluviales urbaines connait une évolution majeure depuis les années 1960 : d'une stratégie basée sur l'évacuation rapide et totale des eaux pluviales de la ville, on passe progressivement à une stratégie de contrôle à la source (CS). Ces 10 dernières années ont vu une généralisation du CS, ainsi qu'en témoigne l'augmentation du nombre de réglementations de rejet. Ces dernières imposent, dans les nouvelles parcelles urbanisées, la réalisation d'ouvrages ayant pour fonction de réguler et/ou de retenir les eaux pluviales : les techniques alternatives (TA). Une systématisation de ces réglementations ne va pas manquer de générer dans l'avenir de nombreux bassins versants urbains fortement équipés en TA, et dont le comportement hydrologique sera déterminé par les réglementations appliquées. Il apparaît que le choix d'une réglementation par une collectivité est un choix complexe et, d'une collectivité à l'autre, des logiques différentes sont appliquées, dont la cohérence globale peut être discutée. Cette thèse questionne et analyse les politiques de CS, et en particulier les réglementations de rejet, dans une perspective de compréhension de leurs effets hydrologiques dans le long terme. Elle comprend deux analyses complémentaires : nous étudions d'abord l'évolution des politiques de CS dans six collectivités en France, afin de déterminer les logiques appliquées dans le choix des réglementations. Nous présentons ensuite une analyse hydrologique des conséquences de ces réglementations sur le comportement de bassins versant urbains "modèles". Cette analyse, centrée sur la modélisation hydrologique des bassins, permet de questionner les politiques de CS actuelles, mais aussi de discuter des outils que l'hydrologie urbaine peut fournir pour permettre la mise en place de politiques de CS cohérentes, en phase avec le fonctionnement hydrologique des bassins versants / Urban stormwater management is facing a major evolution since 1960: from a strategy based on the complete and fast conveyance of stormwater outside of the urban area, to a strategy based on source control (SC). Recently, SC is becoming a common practice, in connection with the increasing diffusion of flow regulations. These regulations prescribe, for all new urban development, to build facilities (Best Management Practices, BMP) to reduce the flow-rate or the volume of stormwater entering the sewer system. A wide application of flow regulations will determine the future hydrological behaviour of many urban catchments. The choice of a regulation is a complex task for local authorities, involving several logics, whose global coherence can be discussed. This thesis analyses SC policies and regulations and discusses them in terms of their long-term hydrological effects. Two complementary approaches are developed. The first is based on the analysis of the evolution of SC policies in six French authorities, and it aims to define and discuss the logics applied. The second consists in the hydrological modelling of the consequences of SC regulations on the behaviour of two experimental catchments. This hydrological analysis allows (i) to evaluate the pertinence of actual SC policies and (ii) to discuss which tools urban hydrology can provide to support the development of coherent SC policies, according to the hydrological functioning of urban catchments

The aim of this dissertation was to develop a multi-criteria decision support system (MCDSS) to allow a specified manager to select with confidence one or many of these BMPs for a particular site. The principal design approach was a review of South African and international literature pertaining to stormwater management techniques, in particular BMPs. This information was formulated into a primary matrix using a rank-and-weighting method. The scores were then checked against the literature to ensure that they were reasonable, culminating in the initial MCDSS. The MCDSS was then provided with seven scenarios, described in the literature, and the output reviewed. Although, the MCDSS would select appropriately when given few criteria for selection when these were increased, inappropriate outcomes resulted. Consequently, weighting factors were assigned to each criterion. The MCDSS was further tested using all the selection criteria and the output deemed satisfactory. The MCDSS was then tested in a case study of the Town Bush stream catchment at eleven sites along the river network and the results were adequate. Taking into consideration the economic aspects of BMP implementation a need also arose for the sites to be allocated to certain authorities depending upon ownership or responsibility. The sites were prioritised depending on potential threat to property and lastly by the hydrological nature of the stream at each site. A stormwater plan for the study area was also proposed. Although the MCDSS was functioning adequately it was not without its limitations. Limitations included the use of drainage areas as a surrogate measure for peak discharge thus, not allowing the user to design a series of BMPs or treatment chain. A second limitation was that initially the BMPs were designed as offline systems where stormwater is managed before entering the channel but in this study they were used as inline systems. Hence the ultimate selection was biased towards those BMPs able to deal with large drainage areas. Recommendations for further improvement include the development of a surrogate measure for drainage area thus allowing the user to design a treatment chain of BMPs; testing the MCDSS in more diverse circumstances; developing a more comprehensive set of selection criteria; and developing a clearer priority-setting model as the one used was rather simplistic. In conclusion the MCDSS provides the user with a useful tool where the selection and implementation of BMPs no longer has to take place in an ad hoc manner. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001

Nature provides essential services to humans, including climate regulation, water provisioning and regulation. These so-called ecosystem services have economical, societal and environmental value. This research aims at improving the knowledge on the linkages between selected hydrological ecosystem services and current and proposed land uses within the water-limited Mpushini/Mkhondeni Catchments in South Africa. The research contributes to the recognition of feedback and linkages within the complex ecological-human system, so that informed land use decisions can be made. The research aim is achieved by first reviewing the literature on hydrological ecosystem services, land use in an ecosystem services context and the links between the two. The study area is then sub-delineated into land use determined hydrological response units for baseline natural land cover, as well as for current and proposed land use scenarios. Using an appropriate model, selected hydrological processes are simulated in order to isolate the effects of individual land uses on hydrological responses, both on a local and a more catchment-wide scale. Various land uses were found to affect hydrological responses, such as runoff and its components of stormflows and baseflows, as well as transpiration and sediment yields, differently. These responses were found to be suitable indicators of selected ecosystem services such as water provisioning or flow regulation. Irrigation and high biomass crops, such as sugarcane and wattle plantations were found to reduce downstream water provisioning services. Degraded lands were found to reduce physical water quality through increased sediment yield, to reduce water provisioning during low flow periods, while the degraded lands increased stormflows, thereby reducing regulation of high flows. Urban land uses were found to significantly increase runoff, with increased impervious areas causing a shift from evaporation and transpiration towards runoff. Stormflows increased, with high flow regulation being reduced. Baseflows increased as well, as a result of a spill-over of runoff from impervious to pervious urban areas, which led to increased low flow regulation. In addition, in this study area urban return flows are generated from externally sourced water, further increasing streamflows and especially low flows. While urban areas showed an increase in downstream water quantity provision, the water quality was reduced. The combined effects of the current land use mosaic on the annual streamflows partially cancel each other out, while the proposed urbanisation dominated hydrological responses. Influences of various land uses on hydrological ecosystem services were thereby shown, which contributes to a better understanding of the linkages between the two. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

The thesis covers the investigation of the storm water runoff and artificial recharge components of the Atlantis Water Resource Management Scheme in the Southwestern Cape. The objective of the study was to obtain an in-depth knowledge of the process of artificial recharge of urban storm water runoff, in order to identify the most efficient recharge management strategy for the Atlantis aquifer. To achieve the objective it was necessary to first study the existing knowledge on urban storm water hydrology and artificial recharge by spreading, and to create a conceptual model of what might be expected. The study area was then investigated to examine how closely the actual situation was reflected by the conceptual model, enabling recommendations to be made for the sound management of the system. The stormwater runoff component was found to differ from most urban hydrological studies as a result of its large baseflow component. The sandy nature of the catchment, small percentage area of effective impervious surface, and high groundwater table resulted in the baseflow constituting more than 40% of the total storm water runoff and accounting for over 60% of the pollution load. The "first flush" effect established as a major source of pollution in other studies, was found to be of minor significance in this study area. The overall stormwater quality (excluding the noxious industrial baseflow) was found acceptable for artificial recharge within the study area, although the baseflow from the industrial sub-catchments showed the potential for being a major source of pollution in the future. The treated wastewater used for artificial recharge prior to 1987 was found to be unacceptable for recharge purposes. The treated industrial effluent should under no circumstances be recharged up-gradient of the Witzand well field. The treated domestic effluent although of a poorer quality than the resident Witzand well field groundwater could be recharged in order to boost recharge volumes and form a buffer against further intrusion by the poor quality groundwater from the Brakkefontein area. This would however only be acceptable if strict water quality control is maintained and recharge does not take place west of the present basin. The recharge basin was found to be well situated with respect to influencing the Witzand wellfield and maintaining a groundwater buffer against poor quality groundwater flow from the northeast towards the central area of the wellfield. Unfortunately the surrounding low-lying topography and sandy retaining walls have resulted in return flow and raised groundwater-levels. The raised groundwater mound does not comply with the conceptual model and together with the sandy nature of the unsaturated zone resulted in less effective purification during infiltration. The practice of letting large portions of the basin floor dry-out during summer was shown to be beneficial and the periodic cleaning of the deeper portions of the basin essential. The artificially recharged water was found to have influenced the upper portion of the aquifer well beyond the West Coast Road. The study of groundwater quality being a good method for tracing artificially recharged water. The groundwater quality has improved as a result of artificial recharge since the removal of treated wastewater from the recharge basin. The groundwater was (ii) found to be very responsive to the slightest changes in recharge basin water quality or/and quantity. Management of the recharge basin therefore had to be very much of a compromise between qualitative and quantitative approaches. The present approach of recharging all the stormwater runoff throughout the year providing the most efficient compromise under the present conditions. The study revealed that the most efficient recharge management strategy would be the recharge of treated domestic sewage effluent in the present recharge basin and all residential storm water runoff plus industrial "storm flow" stormwater runoff in a new recharge basin located northwest of the present basin. Strict water quality control must be maintained on the water discharged into the basins and an annual wet/dry cycle implemented within the basins to boost infiltration. The entire system should continue being monitored to safe guard the groundwater resource from pollution and over exploitation.

Les ouvrages d’infiltration sont utilisés aujourd’hui comme alternative au réseau d’assainissement pluvial. Ils réduisent les risques d’inondation, contribuent au piégeage de polluants permettant ainsi de limiter la détérioration des milieux aquatiques superficiels et sont reconnus pour recharger la nappe. Cependant leur fonctionnement est affecté à long terme par le colmatage réduisant leur performance hydraulique. Par ailleurs, lorsque ces systèmes sont munis de surverses, le colmatage limite les capacités d’interception des flux d’eau et des polluants. Le colmatage constitue donc un facteur clé dans le fonctionnement de ces systèmes tant sur un plan hydraulique qu’environnemental. Cette thèse a pour but de mesurer et de comprendre l’évolution spatio-temporelle du colmatage à une échelle mégascopique (l’échelle d’un ouvrage extensif type) et diachronique (sur le moyen terme). Pour cela une approche expérimentale a été menée au sein de l’Observatoire de Terrain en Hydrologie Urbaine (OTHU) selon trois niveaux d’investigation sur un même ouvrage en conditions réelles de fonctionnement. Un premier niveau (échelle globale) a consisté à mesurer l’évolution temporelle du système pris dans son ensemble grâce au calage de la résistance hydraulique au sens du modèle de Bouwer. Cette étape a nécessité de mesurer et d’exploiter des données en continu de flux d’eau, de sédiments, de matière organique apportés au système, les facteurs environnementaux comme la température d’air et d’eau, l’ensoleillement, le rythme, la nature des événements pluvieux, la saisonnalité, etc., sur un historique de 8 ans. Cette étape nous a mis en évidence la dynamique d’évolution du colmatage et le rôle bénéfique du développement de la végétation sur le maintien de la capacité d’infiltration globale d’un ouvrage de ce type. Un deuxième niveau (échelle semi globale) nous permettant de distinguer l’évolution temporelle du colmatage du fond et des parois, a montré leur dynamique respective (rapide pour le fond, très lente voire inexistante pour les parois). Un troisième niveau (échelle locale) a tenté d’explorer la répartition spatiale et temporelle du colmatage sur le fond des ouvrages sur des échelles de temps plus courtes. L’approche expérimentale a consisté à caractériser la couche colmatante en terme physico chimique et dans une moindre mesure biologique (conductivité hydraulique à saturation, granulométrie, porosité, masse volumique apparente, masse volumique des particules solides, matière organique, biomasse). Elle a analysé également le rôle de la végétation spontanée sur la capacité d’infiltration vis-à-vis des caractéristiques de l’horizon de surface et la structure aérienne et racinaire des espèces présentes. Enfin des analyses statistiques de l’évolution du colmatage à chaque échelle a mis en évidence la part potentiellement importante du colmatage biologique sur ces systèmes alors que, pour la gestion des eaux pluviales ce facteur est généralement négligé. / Infiltration systems are widely used in urban stormwater management. Infiltration systems can significantly reduce stormwater discharges to sewer systems and may therefore contribute to the mitigation of flooding problems. In addition infiltrations systems also help to reduce stormwater pollution, contribute to groundwater recharge and to water course protection. However, the hydraulic performance of infiltration systems decreases with time due to clogging effects. A clogged layer limits the transfer of water and pollutants in infiltrations systems. The clogging has a significant impact on the long-term performance of a system. The aim of this PhD study is to better understand spatio-temporal evolution of clogging on large infiltration systems involving different scales: (i) global scale, (ii) semi - global (the whole bottom and the sides), (iii) local scale (different part of the bottom). An experimental approach has been carried out in the OTHU project (Field Observatory on Urban Hydrology, www.othu.org). An infiltration basin studied with three investigations scales under real operation conditions. In a global scale, the temporal clogging evolution of the system was evaluated in terms of hydraulic resistance. This clogging indicator was calibrated from Bouwer’s model. Water inflow, TSS, COD, climatic factors (air temperature and solar energy), stormwater events and season variations were measured. The results describe the clogging evolution over 8 years. It indicates that vegetation may have a beneficial effect on infiltration capacity. In a semi global scale study, clogging evolution at the bottom and the sides, of the infiltration basin was evaluated. It proved that the clogging mainly occurs at the bottom, that is, the bottom was clogged fast and the clogging at the sides was slow. Local scale study, spatial distribution and temporal evolution of clogging at the bottom with in situ measurements during 2 years were investigated. The study characterised the clogged layer, with bio physic-chemical parameters (i.e., were investigated hydraulic conductivity, porosity, grain size, dry bulk density, organic matter and biomass content). This analyze compared also the role of different types of spontaneous vegetation. The result showed the high spatio-temporal heterogeneity on the infiltration surface. Statistical analysis of clogging evolution in each scale showed the significant impacts of biological activity in the stormwater infiltration basins, which was often neglected