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The Accra Metropolis of Ghana has experienced rapid urban expansion over the past decades. Agricultural and forest-lands have been transformed into urban/built-up areas. This study analysed urban expansion and its relationship with the temperature of Accra from 1986 to 2022. Multi-source datasets such as remote sensing (RS) and other ancillary data were utilised. Land use land cover (LULC) maps were produced employing the random forests classifier. Land surface temperature (LST) and selected d(RS) Indices were extracted. Regression techniques assessed the interplay between LST and remote sensing indices. The LULC maps revealed increasing trends in the urban/built-up areas at the expense of the other LULC types. The analysis from the LST and the RS indices revealed a direct relationship between temperature and urban/built-up areas and an inverse relationship between temperature and vegetation. Thus, spatial urban expansion has modified the urban temperature of Accra. The integrated utilisation of RS and GIS demonstrated to be an efficient approach for analysing and monitoring urban expansion and its relationship with temperature.
Accra and Kumasi are the two major cities in Ghana. Spatial urban expansion has been experienced in transforming different non-urban Land Use Land Cover (LULC) types into urban/built-up areas with a potential direct relationship to temperature rise in the cities. Thus, this dissertation aims to establish the relationship between urban spatial expansion and temperature in Accra and Kumasi metropolis. Multi-source datasets such as remote sensing images, different GIS vector layers, reference maps and historical temperature datasets were used for this retrospective study. This research was grouped under three components: environmental science, environmental technology, as well as environmental management and planning. From the environmental science component, LULC maps were produced for different years to assess the trend of temporal change in the various LULC classes in the two metropolises. Remote sensing indices and land surface temperature were retrieved from the remote sensing images to determine their correlations. Temperature time series was analysed by calculating temperature indices and determining temporal trends to reveal changes in air temperature to detect urban warming and its impacts. From the environmental technology, the novel random forest algorithm was utilised to classify the satellite images of both cities since previous works have utilised other traditional classifiers. The satellite imageries were used for point-based estimation of temperature to determine Urban Heat Islands (UHIs) hotspots. For environmental management and planning, spatial urban expansion techniques were utilised to ascertain trends in urban/built-up areas, especially in both cities' sub-metropolitan zones. For prescient purposes, future LULC modelling was implemented to provide insights into the proportions of the various LULC changes in 2025. The analysis identified two salient findings: increased urban/built-up areas at the expense of agricultural and forestlands throughout the study period and the positive correlation between spatial urban expansion and temperature. This indicated warming up of urban temperature in both cities. The major findings in this dissertation provided evidence of how integrated datasets and research techniques can be utilised for LULC changes to determine the relationship between spatial urban expansion and temperature at local scales. Institutions such as metropolitan assemblies and policymakers may adopt the concepts demonstrated in this work to rapidly assess urban environments and investigate the relationship between spatial urban expansion and temperature.
In anthropogenically heavily impacted river catchments, such as the Lusatian river catchments Spree and Schwarze Elster in Germany, the robust assessment of potential impacts of climate change on the regional water resources is of high relevance for water resources management. Large uncertainties inherent in future scenarios may, however, reduce the willingness of regional stakeholders to develop and implement suitable adaptation strategies to climate change.
This thesis proposes the use of an integrated framework consisting of i) an ensemble based modelling approach and ii) the incorporation of measured and simulated meteorological and hydrological trends to consider uncertainties in climate change impact assessments. In addition, land use, as the most responsive catchment characteristic to buffer potential climate change impacts, is considered as one suitable trigger for climate change adaptation.
The ensemble based modelling approach consists of the meteorological output of four climate downscaling approaches (DAs): two dynamical and two statistical. These DAs drive different model configurations of the two conceptually different hydrological models WaSiM ETH and HBV light. The objective of incorporating measured meteorological trends into the analysis was twofold: trends in measured time series can i) be regarded as harbinger for future change and ii) serve as a mean to validate the results of the DAs. In order to evaluate the nature of the trends, both gradual (Mann Kendall test) and step changes (Pettitt test) are considered as well as temporal and spatial correlations in the data. The suitability of land use change as an adaptation strategy to climate change is evaluated in the form of different land use change scenarios: i) extreme scenarios where the entire catchment is parameterised as coniferous forest and uncultivated land and ii) scenarios of changes in crop cultivation and ii) a combination of a change in crop cultivation and forest conversion. As study areas serve three almost natural subcatchments of the Spree and Schwarze Elster (Germany).
The results of the ensemble based climate change impact analysis show that depending on the type (dynamical or statistical) of DA used, opposing trends in precipitation, actual evapotranspiration and discharge are simulated in the scenario period (2031 2060). While the statistical DAs simulate a decrease in future long term annual precipitation, the dynamical DAs simulate a tendency towards increasing precipitation. The trend analysis suggests that measured precipitation has not changed significantly during the period 1961 2006. Therefore, the strong decrease in precipitation simulated by the statistical DAs should be interpreted as a rather dry future scenario. The dynamical DAs, on the other hand, are too wet in the reference period and needed to be statistically bias corrected which destroys the physical consistency between the parameters. Concerning temperature, measured and simulated trends agree on a positive trend. The uncertainty related to the hydrological model within the climate change modelling chain is comparably low when long term averages are considered but increases during low flow events. The proposed framework of combining an ensemble based modelling approach with trend analysis on measurements is a promising approach to gain more confidence into the final results of climate change impact assessments and to obtain an increased process understanding of the interrelation between climate and water resources.
In terms of climate change adaptation, land use alternatives can have a considerable impact on the water balance components as the analysis of the extreme scenarios revealed. The scenarios of changes in crop cultivation in combination with forest conversion show, however, that the impact on the long term annual water balance is comparably low. An intra annual shift in the water balance components can be triggered which makes these scenarios suitable to reduce low flow risks during the summer. Overall, land use change can serve as one part of an integrated climate change adaptation strategy. Such as strategy needs, depending on the severity of the climate change impact, to include other, especially technical measures of water resources management, such as additional water storage, different strategies to manage the existing and new reservoirs. It may also consider additional water transfers from neighbouring, more water rich, river catchments. Regional adaptation planning needs also to consider problems related to water quality which are a consequence of the long term mining activities in the Lusatian river catchments. Last but not least, adaptation strategies should not only consider climate but also other aspects of global change.
In den Lausitzer Flusseinzugsgebieten bestehen aufgrund eines verhältnismäßig geringen natürlichen Wasserdargebots und durch die Auswirkungen des Braunkohlebergbaus bzw. dessen abrupten Rückgangs in den 1990er Jahren Probleme hinsichtlich der Bereitstellung von Wasser in ausreichenden Menge und Qualität für die vielfältigen Nutzungen. Vor diesem Hintergrund sind die Auswirkungen potenzieller Klima- (ansteigende Temperaturen und sinkende Niederschläge) und Landnutzungsänderungen (weiterer Rückgang des Braunkohlebergbaus sowie verstärkter Anbau agrarischer Energiepflanzen) auf die regionalen Wasserressourcen von besonderem Interesse. Es stellt sich die Frage, in welchem Ausmaß wasserwirtschaftliche Engpässe möglicherweise verschärft werden bzw. durch gezielte Anpassungsmaßnahmen ausgeglichen werden können.
Voraussetzung zur Ableitung von Anpassungsmaßnahmen sind ortsspezifische Antworten hinsichtlich der möglichen Auswirkungen von Klima- und Landnutzungsänderungen auf den natürlichen Wasserhaushalt und die Wassermengenbewirtschaftung. Diese wurden mit einem Ensemble aus den regionalen Klimamodellen STAR und WettReg, Landnutzungsszenarien in Bezug auf Braunkohlebergbau und Energiepflanzenanbau, den hydrologischen Modellen SWIM und EGMO sowie dem Langfristbewirtschaftungsmodell WBalMo untersucht.
Als Grundlage für die Analyse wurden mit dem ökohydrologischen Modellsystem SWIM für die Einzugsgebiete von Schwarzer Elster, Dahme, Spree (bis Pegel Große Tränke) und Lausitzer Neiße (bis Pegel Steinbach) je ein Modell zur Simulation des natürlichen Wasserhaushalts aufgebaut. Der klassische Ansatz zur Modellparametrisierung durch Kalibrierung anhand beobachteter Abflüsse ist aufgrund der starken anthropogenen Überprägung des Abflussgeschehens durch Braunkohlebergbau und Wasserwirtschaft erschwert. Daher erfolgte zunächst eine Kalibrierung für weniger überprägte Teileinzugsgebiete, anschließend wurden die Modellparameter durch Regionalisierung auf die Gesamtgebiete übertragen.
Bei Simulationen mit SWIM für Klimaszenarien mit ansteigender Jahresmitteltemperatur zeigen sich Zunahmen der potenziellen Verdunstung um bis zu 30 % im langjährigen Mittel. Aufgrund der in diesen Szenarien projizierten Abnahme der Niederschlagsjahressummen steigt die mittlere reale Verdunstung nur um bis zu 10 %, weiterhin ergibt sich ein Rückgang der Jahresmittel von Abfluss und Grundwasserneubildung um bis zu 60 %. Ein Rückgang des Grundwasserabsenkungstrichters und damit die Vergrößerung der abflusswirksamen Einzugsgebietsfläche mindert die Auswirkungen der klimatischen Änderungen geringfügig. Bei einem verstärkten Anbau von Winterraps ergeben sich bei gleichem Klimaszenario aufgrund verringerter realer Verdunstung höhere Abflüsse und Grundwasserneubildungsraten im Vergleich zu Winterweizen als Referenzvariante. Die Ergebnisse der natürlichen Wasserhaushaltskomponenten spiegeln hohe Bandbreiten der Klimaprojektionen wider. Unsicherheiten bestehen weiterhin in der hydrologischen Reaktion auf geänderte klimatische Bedingungen, wie Vergleiche der Ergebnisse von SWIM mit denen des hydrologischen Modells EGMO aufzeigen. Im Vergleich dazu sind die mit den Landnutzungsänderungen verbundenen Unsicherheiten eher von untergeordneter Bedeutung.
Durch den Rückgang der natürlichen Abflüsse und von Sümpfungswassereinleitungen ergeben sich in der Simulation der Wassermengenbewirtschaftung mit WBalMo Abnahmen der bewirtschafteten Abflüsse um bis zu 50 %. Das hätte zur Folge, dass die Nutzeransprüche nicht mehr ausreichend erfüllt werden können. Es zeigte sich, dass die negativen Auswirkungen der Klima- und Landnutzungsänderungen durch wasserwirtschaftliche Maßnahmen innerhalb des Untersuchungsgebiets, wie zum Beispiel eine geänderte Speicherbewirtschaftung, nicht ausreichend gemindert werden, die Überleitung von Wasser aus der Elbe jedoch eine geeignete Anpassungsoption darstellt. Die Unsicherheiten bezüglich der natürlichen Wasserhaushaltskomponenten ziehen in der Simulation der Wassermengenbewirtschaftung hohe Bandbreiten der Ergebnisse nach sich.
Der Ansatz der ensemblegestützten Analyse erlaubt es, Auswirkungen potenzieller Klima- und Landnutzungsänderungen auf die natürlichen Wasserhaushaltskomponenten und die Wassermengenbewirtschaftung abzuschätzen und damit verbundene Unsicherheiten zu berücksichtigen sowie mögliche Anpassungsoptionen zu identifizieren.
Ecological Land-Use Planning (ELUP) is the central strategy implemented in Mexico to achieve sustainable development. However, even after more than a decade of experience there are no concrete evaluations to determine how the implemented ELUP-Programmes (ELUPP) have influenced regional development and thus what the consequences on the environment are. In this investigation, some of the key stages of the Strategic Environmental Assessment (SEA) are carried out on the ELUPP Cancun-Tulum, which is considered to be one of the most important land-use programmes in Mexico. Aim of the study: To achieve the SEA key principles, i.e. to identify reasonable alternatives and to improve the ELUPP Cancun-Tulum. Special emphasis is dedicated to the selection of environmental indicators for monitoring and to the supervision of the programme implementation using a GIS-remote sensing approach. Method of investigation: The baseline environment in the Riviera Maya and the ELUPP Cancun-Tulum’s framework are first examined. Next, an identification of alternatives at regional level is effectuated using geographic information systems (GIS). A monitoring scheme is then proposed to supervise the implementation of the ELUPP Cancun-Tulum. The supervision mechanism is based on a pressure-state-response (PSR) indicator framework. Finally, six environmental indicators are examined using GIS-remote sensing techniques. The assessment encompasses the remote sensing interpretation of two Landsat Geocover Mosaics, and the determination of six landscape spatial indices to evaluate extend and pattern of fragmentation of vegetation. Results and technical applicability: A reasonable alternative site location for the development of New Tulum (which is one of the cities included in the ELUPP Cancun-Tulum) was proposed. A monitoring mechanism was suggested to supervise the ELUP implementation, including the identification of 19 environmental indicators. The GIS-remote sensing analysis demonstrated that there has been a reduction in the total area of habitat available and that fragmentation of vegetation increased in the Riviera Maya. The results reported here can be used to improve the ELUPP Cancun-Tulum. In addition, this investigation may be useful to improve other ELUP-Programmes in Mexico.
Desertification is seen as a severe threat to Mediterranean ecosystems and the desert fringes. Both land use and climate variations may lead to an advance of the desert, and human and natural factors can be connected in feedback relationships. This makes it difficult to describe cause-and-effect relationships, and to predict the impact of global warming. A key is understanding historic desertification, since the investigation of the past allows to better separate the roles of man and weather. These questions were investigated in the Decapolis region in northern Jordan, an area in the transition zone between the Arabian desert and the Mediterranean climate belt. It had been assumed that historic desertification in the Decapolis was connected with severe degradation of soils, and caused by agricultural mismanagement and deforestation. This idea served as explanation for economic decay and abandonment of cities, too. However, the greatest part of the erosion took place during the last Ice Age and the Younger Dryas. There is no indication that the inanimate landscape changed significantly since the Bronze Age. Historic field systems were partially preserved and seem reflected by distinct soil development, indicating that the impact of land use was more complex and less devastating than previously assumed. Historic human impacts on the natural environment seem limited, and certainly not connected with desertification. Romantic northern European misconceptions of how a "natural" landscape should look like may in this context have contributed to a negative assessment of traditional agriculture in the Mediterranean. Comparative analyses of soils and colluvia, air photos, historic travel reports, tree rings and climate reconstructions indicate that population growth was behind the flourishing of the Decapolis, which took place mostly under favourably stable climatic conditions. Periods of decline seem triggered by climatic anomalies. As it seems, climate change was previously understood too linearly: extreme rainfall events can be more devastating than drought, and temperature, wind and rainfall distribution over the year are important as well. Cool and dry periods at the end of the last Ice Age were connected with incision and sometimes dramatic erosion. Climatic fluctuations during history may have been connected with pests, famines, plagues, and wars which caused dramatic drops of population levels. The ecological sensitivity of the desert belt may have aggravated the impact of climate variations. Economic recovery took place only when population levels rose again. It is so far unknown how climate will develop under global warming, but an increasing number of anomalous events could have dramatic impacts. The key for dealing with global warming seems therefore adaptation to climatic irregularities.