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Numerous research studies have been conducted on the modification of weather and local climate by the urban environment. In studying the urban environment effects, researchers have investigated the urban heat island (UHI), anthropogenic cloud condensation nuclei, anthropogenic heat emissions and other factors. Many of these studies used data sampling networks, while other studies relied solely on computer modeling. This research has taken an approach between the sampling network studies (which were often limited in spatial density) and the pure computer model studies (which lacked the benefits of observational data) to investigate the Tampa Bay Region UHI. The research utilized inexpensive commercially available temperature logging sensors within a 525 km² study area. One hundred temperature logging sensors, deployed within the study area, generated in excess of 250,000 time and temperature data points for analysis. The large number of temperature sensors enabled the generation of detailed spatiotemporal maps of the Tampa Bay Region UHI. Analysis of the data revealed a significant relationship between the percentage of impervious surface in the study area and the intensity of the local UHI delta temperatures. In addition, the analysis identified the existence of micro UHIs within residential areas. These micro UHIs affected readings within the residential areas. In conjunction with the investigation of the relationship between the percentage of impervious surface and the generation of a UHI, wind speed's role as a moderating factor was also investigated. It was found that increases in wind speed are correlated with a lessoning of the observed UHI. Wind speeds above approximately 2 ms-1 exhibit a significant negative relationship to the development of a UHI. The results of this study add to the field of UHI research in subtropical environments.

Changes in land use and land cover (LULC) attributed to anthropogenic activities are one of the fundamental drivers of environmental changes at the local, regional and global levels. These changes continue to threaten the capacity of the ecosystems to function and provide environmental goods and services and the ability to sustain the livelihoods of rural communities. Therefore, a critical understanding of LULC patterns and dynamics is crucial for predicting future LULC patterns and changes and formulation of appropriate policies, strategies and interventions for sustainable management of natural resources. Dedza district like any other district in Malawi has experienced rapid LULC changes over the past decades. However, knowledge about LULC changes that occur, where and when they occur and the rates at which they occur is not well documented. Equally important is the examination of the drivers and processes that cause these changes and the extent to which these LULC changes have impacted on natural resources and rural livelihoods in the studied area. As such, this remains a critical challenge that needs to be addressed in order to achieve sustainable natural resource management and community development. This study aimed to investigate the nature of LULC changes that have taken place between 1991 and 2015, drivers attributing to these changes and their impacts of these changes on the natural resources in Dedza district of Malawi. The study used a mixed-method approach consisting of remote sensing and Geographic Information System (GIS)-based analysis, model simulations, focus-group discussions, key informant interviews, and semi-structured interviews covering 586 households. An overall accuracy of the classification achieved for the classified images was 91.86%. GIS-based analysis of remotely sensed data revealed that the areas under agricultural land, forest area, wetlands, water bodies drastically decreased from 71.3% (267,977.43 ha), 24.53% (9,939.15 ha), 0.96% (3,626.73 ha), 0.37% (1,380.60 ha) in 1991 to 69.41% (260,879.31 ha), 1.66% (6,237.63 ha), 0.71% (2,680.29 ha) and 0.24% (899.55 ha) in 2015. On the contrary, barren land and built-up areas substantially increased from 24.53% (92,185.38 ha) and 0.20% (761.67 ha) in 1991 to 25.85% (97,174.62 ha), 2.13% (7,999.56 ha) in 2015 respectively. Significant differences were found among the interviewed households in perceptions regarding LULC changes taken place in the studied landscape and distance to different infrastructures such as main roads, health centres, schools, and towns (p < 0.001). The results of the household surveys indicated that the local communities were aware of the LULC dynamics and validated the observed changes. Firewood collection, charcoal production, population growth, and poverty were identified as the key drivers of observed LULC changes in the study area. Local communities perceived that LULC changes led to a decline in agricultural land (57.3%, n = 586), crop production (82.8%, n = 586) and forest cover (87.4%, n = 586) and an increase in the distance to forest resources (50.7%, n = 586). These changes exposed rural households to major shocks such as drought, floods, food shortage, loss/damage of crops and death of household members. In order to address these shocks, communities were engaged in short-term strategies such as piecework, receiving aid from government and NGOs, receiving unconditional aid from relatives, relying on their own savings and credits. The simulation results using the CA-Markov model showed that water bodies, barren land and built-up areas will increase while agricultural land, wetlands and forest land will substantially decrease by 2025 and 2035. The undesired LULC changes, patterns and impacts observed in this study, however, pose a big threat and risk to the sustainable management of natural resources and rural livelihoods survival. Hence, the need for urgent attention by the natural resource managers, planners, researchers and decision-makers. The results found in this study are deemed useful in guiding planners and decision-makers in the field of land management and policy development towards a more sustainable natural resource management strategy in Dedza district. Results found in this study could also inform decision-making in other districts of similar settings. Thus, results of the study are expected to support decision-makers and planners in the design and implementation of holistic, tenable and coherent and sustainable development policies/strategies/ guidelines for effective natural resource management. / Thesis (PhD)--University of Pretoria, 2019. / Geography, Geoinformatics and Meteorology / PhD / Unrestricted

Urbanization is one of the most significant phenomena of the anthropogenic influence on the Earth’s environment. One of the principal results of the urbanization is the creation of megacities, with their local climate and high impact on the surrounding area. The design and evolution of an urban area leads to higher absorption of solar radiation and heat storage in which is the foundation of the urban heat island phenomenon. Remote sensing data is a valuable source of information for urban climatology studies. The main objective of this thesis research is to examine the relationship between land use and land cover types and corresponding land surface temperature, as well as the urban heat island effect and changes in these factors over a 10 year period. 10 megacities around the world where included in this study namely Beijing (China), Delhi (India), Dhaka (Bangladesh), Los Angeles (USA), London (UK), Mexico City (Mexico), Moscow (Russia), New York City (USA), Sao Paulo (Brazil) and Tokyo (Japan). Landsat satellite data were used to extract land use/land cover information and their changes for the abovementioned cities. Land surface temperature was retrieved from Landsat thermal images. The relationship between land surface temperature and landuse/land-cover classes, as well as the normalized vegetation index (NDVI) was analyzed. The results indicate that land surface temperature can be related to land use/land cover classes in most cases. Vegetated and undisturbed natural areas enjoy lower surface temperature, than developed urban areas with little vegetation. However, the cities show different trends, both in terms of the size and spatial distribution of urban heat island. Also, megacities from developed countries tend to grow at a slower pace and thus face less urban heat island effects than megacities in developing countries.

The ecosystem services approach has increased throughout the years, becoming a powerful tool for environmental planning as well as guideline for resources management and decision-making. Changes in land use/cover are the main human-driven impact over natural ecosystems, which implies directly in ecosystem services provisioning capacity and the ability to sustain those benefits. Water resources are strongly related to human well-being and survival, as one of the most valuable benefits humans acquire from nature. In this regard, landscapes suffering from extreme or vast changes in land use/cover represent threats over water resources, as is the case for Brazilian Cerrado savannas. The prediction of impacts of land cover exchanges over water-related ecosystem services may become one way to avoid its loss, diminishing uncertainties in decision making of land uses. In this sense, our work aimed the measurement and recognition of thresholds that indicates changes in the availability of seven essential water-related ecosystem services, within Cerrado landscapes of São Paulo State, that are facing the conversion of native forests into eucalyptus plantations. We analyzed water resources at 11 low order catchments which comprised a gradient of forested savanna and eucalyptus plantations. Stream water quality data were obtained for 13 physical-chemical-biological parameters, previously known as indicators for seven water-related ecosystem services. Results highlight the importance of monitoring Turbidity, pH, electric conductivity as indicators of services provision. Best potential gains of the seven services occurred above 45% of natural forest coverage. Landscapes with less than 20% of forest tend to become too unsustainable / A abordagem dos serviços ecossistêmicos aumentou ao longo dos anos, tornando-se uma ferramenta poderosa para o planejamento ambiental, guiando a tomada de decisão sobre o manejo de recursos naturais. Mudanças no uso/cobertura da terra são os principais impactos sobre os ecossistemas naturais, o que implica diretamente na provisão de serviços, e na capacidade do ambiente de sustentar esses benefícios. A água fornece diversos serviços ecossistêmicos hídricos, vitais para a sobrevivência humana. Então, neste contexto, paisagens submetidas a vastas mudanças de uso e cobertura representam uma séria ameaça aos serviços hídricos, como é o caso das áreas em domínio de Cerrado brasileiro. Prever e valorar as conseqüências da conversão de áreas naturais para usos da terra sobre os serviços hídricos pode se tornar uma forma de evitar sua perda e diminuir as incertezas nos processos de tomada de decisão territorial. Com esse propósito, objetivamos mensurar e definir limiares em relação às mudanças na disponibilidade de sete serviços essenciais de água em paisagens savânicas do Estado de São Paulo que sofreram conversão de florestas nativas para reflorestamentos. Analisamos recursos hídricos de onze bacias hidrográficas de pequena ordem, que compreendem composições de sistemas florestados em contato com florestas plantadas de eucalipto. As amostras de água foram avaliadas por meio de treze parâmetros físico-químico-biológicos, presumidos como indicadores de sete serviços hídricos. Os resultados ressaltaram a importância de Turbidez, pH e condutividade elétrica como elementos indicadores da provisão dos serviços. Os melhores ganhos potenciais na provisão ocorreram a partir de 45% de cobertura florestal. Paisagens com menos do que 20% de florestas naturais tendem a tornarem-se menos sustentáveis para a provisão de todos os serviços somados

This thesis aims to establish analytical frameworks to map urban growth patterns with spaceborne remote sensing data and to evaluate environmental impacts through Landscape Metrics and Ecosystem Services. Urbanization patterns at regional scale were evaluated in China's largest urban agglomerations and at metropolitan scale in Shanghai, Stockholm and Beijing using medium resolution optical satellite data. High-resolution data was used to investigate changes in Shanghai’s urban core. The images were co-registered and mosaicked. Tasseled Cap transformations and texture features were used to increase class separabilities prior to pixel-based Random Forest and SVM classifications. Urban land cover in Shanghai and Beijing were derived through object-based SVM classification in KTH-SEG. After post-classification refinements, urbanization indices, Ecosystem Services and Landscape Metrics were used to quantify and characterize environmental impact. Urban growth was observed in all studies. China's urban agglomerations showed most prominent urbanization trends. Stockholm’s urban extent increased only little with minor environmental implications. On a regional/metropolitan scale, urban expansion progressed predominately at the expense of agriculture. Investigating urbanization patterns at higher detail revealed trends that counteracted negative urbanization effects in Shanghai's core and Beijing's urban-rural fringe. Beijing's growth resulted in Ecosystem Services losses through landscape structural changes, i.e. service area decreases, edge contamination or fragmentation. Methodological frameworks to characterize urbanization trends at different scales based on remotely sensed data were developed. For detailed urban analyses high-resolution data are recommended whereas medium-resolution data at metropolitan/regional scales is suggested. The Ecosystem Service concept was extended with Landscape Metrics to create a more differentiated picture of urbanization effects.​ / <p>QC 20160205</p>

Although mosquito monitoring systems in the form of dry-ice bated CDC light traps and sentinel chickens are used by mosquito control personnel in Polk County, Florida, the placement of these are random and do not necessarily reflect prevalent areas of vector mosquito populations. This can result in significant health, economic, and social impacts during disease outbreaks. Of these vector mosquitoes Culex nigripalpus, Culex erraticus, Coquillettidia perturbans, and Aedes vexans are present in Polk County and known to transmit multiple diseases, posing a public health concern. This study seeks to evaluate the effect of Land use Land cover (LULC) unique features and precipitation on spatial and temporal distribution of Cx. nigripalpus, Cx. erraticus, Cq. perturbans, and Ae. vexans in Polk County, Florida, during 2013 and 2014, using negative binomial regression on count data from eight environmentally unique light traps retrieved from Polk County Mosquito Control. The negative binomial regression revealed a statistical association among mosquito species for precipitation and LULC features during the two-year study period, with precipitation proving to be the most significant factor in mosquito count numbers. The findings from this study can aid in more precise targeting of mosquito species, saving time and resources on already stressed public health services.

The Green Swamp Preserve is a large geographic area that has sustained many changes since Europeans settled in Florida. There has been little published research on the impacts of anthropogenic activity on this system. This thesis research seeks to document more recent changes in the Green Swamp and to evaluate the effects of various human activities on the system. The study period is from 1985 to 2015. For this time period changes in land use and landcover were examined using neural network classifications. Changes in vegetation health were evaluated by examining Normalized Difference Vegetation Index (NDVI) and Green Vegetation Index differences. Field site visits were made to document current conditions at thirty sample locations within the study area. Changes in land use and landcover and vegetation health were evaluated in relation to anthropogenic activities such as proximity to pollution sources, conservation lands and restoration sites. Statistical analysis was conducted to determine if statistically significant clustering occurred in these changes and if present geographically weighted regressions were performed to determine if a significant spatial relationship existed between the clustering and the various human activities. WAP data showed an overall decline in wetland health at the assessment sites and showed a trend of lower wetland health at sites within 2 Km of pollution sources, specifically petroleum tank contamination sites and state roads. The statistically significant clustering identified in land use landcover changes from 1985 to 2015 were in relation to changes from field, forested and wetland landcover types to built environments. Spatial relationships were identified between the proximity of petroleum tank contamination sites, state roads and solid waste facilities and clustering of NDVI decreases from 1985 to 2015. NDVI increases in the study area from 1985 to 2015 also showed statistically significant clustering in relation to conservation lands and lands purchased by the Southwest Florida Water Management District for environmental protection. These preliminary findings suggest that human activities may have influenced changes in the health of the Green Swamp. Further, more extensive research is suggested to confirm these findings.

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