Improving Flood Detection and Monitoring through Remote Sensing

As climate-change- and human-induced floods inflict increasing costs upon the planet, both in terms of lives and environmental damage, flood monitoring tools derived from remote sensing platforms have undergone improvements in their performance and capabilities in terms of spectral, spatial and temporal extents and resolutions. Such improvements raise new challenges connected to data analysis and interpretation, in terms of, e.g., effectively discerning the presence of floodwaters in different land-cover types and environmental conditions or refining the accuracy of detection algorithms. In this sense, high expectations are placed on new methods that integrate information obtained from multiple techniques, platforms, sensors, bands and acquisition times. Moreover, the assessment of such techniques strongly benefits from collaboration with hydrological and/or hydraulic modeling of the evolution of flood events. The aim of this Special Issue is to provide an overview of recent advancements in the state of the art of flood monitoring methods and techniques derived from remotely sensed data

Reaching the sea: Guangzhou southern expansion from rural industrialization to polarized strategical planning

At the turning point of the new century Chinese urban growth has arrived to a new challenge: the improvement of its urban space after the astonishing development of the late Eighties and Nineties. At that time many scholars, impressed by the great urban sprawl occurring in China and other Asian regions, tried to conceptualize models in order to explain that particular phenomenon of the peri-urban dispersion. The paper wants to explore, selecting the city of Guangzhou as case study, capitol of Guangdong Province, which are the most influential passages that could demonstrate how much policy has influenced the management of the urban spatial growth. Analysing a system of driving forces, derived from the market but managed by the political system, and comparing them with the mapping of the city growth in a temporal dynamic selection, it’s possible to understand that South China cities had to change their planning from agglomeration to strategical organization in order to survive. In this way Guangzhou has achieved the possibility to redefine its leading role inside the Pearl River Metropolis, improving urban space from dispersion to a multi-polar and specialized system

Investigation into land-use change in two contrasting areas in the Nile Delta, Egypt

Understanding land-use change in developing countries, particularly those situated in environmentally vulnerable and and semi-arid zones, is crucial given the considerable pressures arising due to rapid population growth, climate change and desertification. The purpose of this research was to investigate the main drivers affecting land-use change in the eastern part of the Nile Delta, Egypt in the last two decades. Two contrasting cities in the region were selected for detailed analysis. Almansourah is an ancient settlement relatively close to the Damietta branch of the Nile whereas Alzaqazig is a recent development and the surrounding area was reclaimed from the desert. The DPSIR (driving forces, pressures, state, impacts and responses) model was adopted as the conceptual framework for organising and categorising the factors affecting landuse change in these two areas. It is a linear, `formulaic' approach, based on the concept of causality chains which connect human activities with environmental information. The case study approach was used as the main methodology, although both qualitative and quantitative techniques were employed throughout. A range of sources were consulted throughout the investigation to ensure that the evidence was internally consistent: remote sensing data, questionnaire data, interviews, participant observation and census data. More than 180 farmers were interviewed in the two study areas and the majority of these (71%) farmed less than 2ha. Using remote sensing data it was found that crop patterns had changed considerably in the two areas both with regard to their geographical distribution and extent. In the Almansourah study area, the key changes during the past two decades were the increase of cotton area and the decrease in rice, maize and other crops. In contrast, the Alzagazig study area experienced an increase in cotton and rice area with minor increase in maize fields. There was also an expansion of urban and rural-urban settlements into agricultural land in both the study areas.One of the critical physical factors for land-use change was found to be the need for irrigation water. Regarding the two study areas, Almansourah currently enjoys greater availability of irrigation water because of its proximity to the Nile compared to Alzagazig which facilitated land-use change in Almansourah. On a more general level the aridity of the Nile Delta region makes water a limiting factor in agricultural production. Analysis of the driving forces showed that land-use change was highly dependent on economic factors such as transportation availability and cost as well as the contribution of women. Land-use change was significantly influenced by transportation availability in Almansourah but not in Alzaqazig possibly because of the greater need to transport agricultural produce to market. Social drivers were also found to be significant. One significant pressure was caused by population growth; in Almansourah the lack of alternative sources of land led to the expansion of urban and rural urban settlements onto fertile agricultural fields. The study confirmed that a farmer's educational level plays an important role in agricultural production. Almost 25% of farmers in Almansourah and 30% in Alzaqaziq had no formal education and this difference led to variations in land-use change between the areas. Education level was found to have a considerable influence on crop rotation and manure use in the Almansourah study area. Conversely, subsidies from private financial sources and rural women's contribution to agricultural production were among the key drivers for land-use change in the Alzaqazig study area. One of the innovative aspects of this study was the application of the DPSIR framework. Although it has been used to advantage in the developed world, it has not been applied to study land-use change in an arid, developing country. The study confirmed that the framework worked well in such a context. Notable strengths included its comprehensive nature, ability to deal with uncertainty and handle different types of data. A further advantage was that it could incorporate sub-models to investigate individual driving forces, for example, the need for irrigation water. Overall the use of DPSIR was flexible enough to highlight the major causative drivers affecting land-use and also to take account of the action of more subtle and complex factors.The University of Damascus, Syria anthe University of Plymout

Urban Expansion, Land Use Land Cover Change and Human Impacts: A Case Study of Rawalpindi

Urbanization in Pakistan has increased rapidly from 25% in 1972 to 42% in 2012. Peripheral zones are being pushed by urbanization much beyond their previous extents. Moreover, dispersed developments along the highways/motorways and unplanned expansion of existing urban centres is instigating a substantial loss of vegetation and open spaces. This research is an effort to analyse the relationship between urban expansion and land use/cover change using a combination of remote sensing, census and field data. Rawalpindi has been chosen as a study area because of its rapidly changing population density and land cover over the last few decades, and availability of satellite and census data. Landsat MSS and TM images of 1972, 1979, 1998 and 2010 which are compatible with the 1972, 1981, 1998 and 2012 Census of Pakistan dates were classified using the Maximum Likelihood classifier. The results of the assessment of classification accuracy yielded an overall accuracy of 75.16%, 72.5%, for Landsat MSS 1972, 1979 images and 84.5% and 87.1% for Landsat TM 1998 and 2010 images. Results reveal that the built up area of the study area has been increased from 7,017 hectares to 36,220 hectares during the 1972 -2012 period. This expansion has been accompanied by the loss of agricultural and forest land. There has been a decrease of approximately 10,000 hectares in cropped area and 2,000 hectares in forest land of the study area during the 1998-2012 inter-censal period. Corroboration of official census data, remote sensing results and field based qualitative data supports the view that high population growth rate, industrialization, better educational and transportation facilities and proximity of the study area to the capital (Islamabad) are the major factors of urban expansion and resulting land cover changes The present research is expected to have significant implications for other rapidly urbanizing areas of Pakistan in particular, and the Global South in general, in delivering baseline information about long term land use/cover changes

A Field Survey and Geographical Information Systems (GIS) Based Investigation of the Archaeological Landscape in the Niger River Valley, Republic of Benin

Abstract The Niger River Valley in the Republic of Benin is an archaeologically rich landscape, where hundreds of sites line the river’s tributaries. Before this doctoral research was conducted in the region, the landscape here was a terra-incognita. In order to archaeologically investigate the area, several methods were used consisting of a field walking survey, and the use of satellite remote sensing and Geographical Information Systems (GIS). An integration of these methods, which are commonly used in research out of Africa, showed the diverse nature of archaeology in this region. The field walking survey revealed the position of over 300 sites and around 50,000 material culture artefacts, comprising of mainly ceramic vessel sherds. The field survey was undertaken over 45 days and covered a total area of 25km2 within four geographical zones in the study area. A comprehensive gazetteer was produced from the data collected. Remote sensing methods that manipulate multispectral satellite imagery were used to identify sites from the air, because the archaeology of this region is not visible from standard air photographs. The mapping of sites using GIS facilitated in establishing fundamental landscape patterns, which helped substantiate theories surrounding West African urbanism and human-environment interactions. The results conveyed that settlements in this region favour areas where water is available, mainly close to perennial and ephemeral fluvial systems. Furthermore, the archaeological sites identified display strong evidence of spatial clustering, which has been shown in other West African contexts to be indicative of early urbanisation

Land Use Change from Non-urban to Urban Areas

This reprint is related to land-use change and non-urban and urban relationships at all spatiotemporal scales and also focuses on land-use planning and regulatory strategies for a sustainable future. Spatiotemporal dynamics, socioeconomic implication, water supply problems and deforestation land degradation (e.g., increase of imperviousness surfaces) produced by urban expansion and their resource requirements are of particular interest. The Guest Editors expect that this reprint will contribute to sustainable development in non-urban and urban areas

Advancing large-scale analysis of human settlements and their dynamics

Due to the importance for a range of sustainability challenges, it is important to understand the spatial dynamics of human settlements. The rapid expansion of built-up land is among the most extensive global land changes, even though built-up land occupies only a small fraction of the terrestrial biosphere. Moreover, the different ways in which human settlements are manifested are crucially important for their environmental and socioeconomic impacts. Yet, current analysis of human settlements heavily relies on land cover datasets, which typically have only one class to represent human settlements. Consequently, the analysis of human settlements does often not account for the heterogeneity within urban environment or their subtle changes. This simplistic representation severely limits our understanding of change processes in human settlements, as well as our capacity to assess socioeconomic and environmental impacts. This thesis aims to advance large-scale analysis of human settlements and their dynamics through the lens of land systems, with a specific focus on the role of land-use intensity. Chapter 2 explores the use of human settlement systems as an approach to understanding their variation in space and changes over time. Results show that settlement systems exist along a density gradient, and their change trajectories are typically gradual and incremental. In addition, results indicate that the total increase in built-up land in village landscapes outweighs that of dense urban regions. This chapter suggests that we should characterize human settlements more comprehensively to advance the analysis of human settlements, going beyond the emergence of new built-up land in a few mega-cities only. In Chapter 3, urban land-use intensity is operationalized by the horizontal and vertical spatial patterns of buildings. Particularly, I trained three random forest models to estimate building footprint, height, and volume, respectively, at a 1-km resolution for Europe, the US, and China. The models yield R2 values of 0.90, 0.81, and 0.88 for building footprint, height, and volume, respectively. The correlation between building footprint and building height at a pixel level was 0.66, illustrating the relevance of mapping these properties independently. Chapter 4 builds on the methodological approach presented in chapter 3. Specifically, it presents an improved approach to mapping 3D built-up patterns (i.e., 3D building structure), and applies this to map building footprint, height, and volume at a global scale. The methodological improvement includes an optimized model structure, additional explanatory variables, and updated input data. I find distance decay functions from the centre of the city to its outskirts for all three properties for major cities in all continents. Yet, again, the height, footprint (density), and volume differ drastically across these cities. Chapter 5 uses built-up land per person as an operationalization for urban land-use intensity, in order to investigate its temporal dynamics at a global scale. Results suggest that the decrease of urban land-use intensity relates to 38.3%, 49.6%, and 37.5% of the built-up land expansion in the three periods during 1975-2015, but with large local variations. In the Global South, densification often happens in regions where human settlements are already used intensively, suggesting potential trade-offs with other living standards. These chapters represent the recent advancements in large-scale analysis of human settlements by revealing a large variation in urban fabric. Urban densification is widely acknowledged as one of the tangible solutions to satisfy the increased land demand for human settlement while conserving other land, suggesting the relevance of these findings to inform sustainable development. Nevertheless, local settlement trajectories towards intensive forms should also be guided in a large-scale context with broad considerations, including the quality of life for inhabitants, because these trade-offs and synergies remain largely unexplored in this analysis

Elephant space use in relation to ephemeral surface water availability in the eastern Okavango Panhandle, Botswana

The movement and distribution of elephants can be influenced by environmental factors over time (Foley, 2002). Examining how features in the landscape such as vegetation productivity, water sources and anthropogenic activities drive the movement of elephants can help in understanding patterns of movement. It can also help to inform the establishment and alignment of protected areas, wildlife corridors and identification of tourism hotspots as well as policy interventions to manage Human-Elephant Conflict (HEC). The Okavango Panhandle in Botswana is a HEC hotspot and the focus of My study. A number of strategies to address HEC are underway in the area, however one longer term strategy that has been proposed in this area involves provision of artificial water sources to influence elephant movements and keep animals away from fields during the cropping season. However, an improved understanding of how elephants utilize their habitats in relation to natural ephemeral surface water and other factors that influence their movements from dryland habitats to the Okavango Delta resources is needed to inform such management decisions. My study seeks to establish the role of ephemeral surface water on elephant distribution in the eastern Okavango Panhandle, Botswana as well as assess the movement distribution of elephants in relation to the seasonality, proximity and spatial extent of water presence represented by ephemeral surface water. Time series analysis of water extent on ephemeral surface water of the eastern Okavango panhandle will be developed and overlaid with elephant movement datasets. Elephant collar data from 15 elephants (5 males and 10 females) in the eastern Okavango Panhandle, Botswana have been analysed and Home Range (HR) sizes estimated using Kernel Density Estimation (KDE). The relative importance/probability of environmental variables in determining elephants' movement based on the Utilization Distribution (UD) were computed using Generalized Linear Mixed Models (GLMMs). I utilized a remote sensing spectral index, namely the Automated Water Extraction Index (AWEI) to delineate ephemeral surface water in dryland (excluding permanent waters) of the study area. The results reveal that during the wet season, elephants were evenly spread out all over the study area until the early dry season (April-June) when the ephemeral waterholes dried up. Elephants moved southwards towards the permanent waters of the Okavango River, where there are many human settlements and farms. Male HR sizes were found to be bigger than those of female elephants. Wet season (early and late) home range sizes were also bigger when compared to dry season (early and late) HR size. Mean daily distances were computed to investigate the effect of season on elephant daily distances and the distances ranged between 5km and 6.8km in the late wet and in the early wet and late dry season respectively. The Resource Selection Function (RSF) analysis shows that water adjacent sites are preferred over distant ones and both sexes prefer areas with high NDVI, with this preference being more pronounced in males. The seasonal variation of water use is notable in that it affirms the importance of proximity to water for elephants and has implications for their management and HEC. For example, I found that ephemeral surface water has a significant role in influencing elephant spatial use in the area, particularly during the early and late wet season. As ephemeral pans dried and NDVI (vegetation greenness) decreased, elephants started to move closer to the Okavango Delta and consequently human settlements and fields. However, further investigations into the timing of movements away from ephemeral waterholes and the influence of other environmental factors on elephant movements in the area would be needed before any recommendations can be made regarding artificial water provision in this area

Late Holocene cultural dynamics and trans-Saharan connections in Southeastern Mauritani: a remote sensing approach

This doctoral thesis investigates the prehistoric and medieval archaeological record of southeastern Mauritania (c. 2,000 BC to AD 1,100). The highlands of southeastern Mauritania present an extraordinary archaeological record for documenting the emergence, consolidation, and reorganisation of cultural dynamics. A remote sensing approach represents the most viable research methodology, politically and logistically, for this study. My work integrates quantitative methods and transdisciplinary theoretical developments to characterize and assess diachronic cultural trends in terms of regional settlement dynamics, the nature of funerary landscapes, and supra-regional connectivity. The results include the identification and spatial distribution mapping of >9,000 funerary tumuli and 1,140 settlements belonging to the Tichitt Tradition, many of which were previously unpublished or undocumented. The Tichitt Tradition represents the growth and consolidation of a thriving agropastoral economy based on cattle-keeping and pearl millet (Pennisetum glaucum) cultivation throughout during the second millennium BC, structured around extensive, drystone settlements. I interpret these Late Holocene cultural dynamics through the lens of Complex Adaptive Systems, unfolding within the cultural milieu of pre-colonial African polities. The expansion of Tichitt Tradition communities was characterized a conservative but decentralized reproduction of material and ideological forms leading to high systemic coherence, conforming to Kopytoff’s Internal African Model. From the first millennium BC, Tichitt Tradition communities witnessed a drastic release and reorganisation of settlement patterns amidst severe aridification trends and the arrival of Lybico-Berber groups. This scenario led to migration outflows and the formation of interstitial communities with greater adaptive creativity, reflected in a greater diversity of settlement styles and the syncretism of pottery traditions described by Kevin MacDonald. The interplay between concepts of spatial and socio-political centrality and liminality—illustrated by the shifting trends of funerary monument clustering in relation to settlement centers—highlights issues of translocal resilience and landscape memorialisation among agropastoral communities in dryland ecosystems