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Thresholds and Contingencies: A Design Process for Regional Coastal Resilience
Published in Elizabeth Mossop, Sustainable Coastal Design and Planning, 2018
We used a case study site on a 500-hectare coastal farm in the Horowhenua (Figure 17.2). Tahamata Incorporation is a shareholder, collectively owned coastal farm with a Board of Directors governed by the 1993 Te Ture Whenua Māori Act. The land is low-lying coastal plain: part land, part water, with a high-water table, extensive wetlands, and a meandering river, which makes it particularly vulnerable to a wide range of impacts, including pollution from dairy farming and flooding caused by storm surge and groundwater inundation. As part of our speculative design approach, we proposed a series of land-based spatial strategies that could be implemented by farmers over time, together with exhibitions in a variety of venues to capture the design work in progress, raising awareness of the issues among farmers, politicians, and the local community while receiving feedback that encouraged local ownership for the project.
Design, reliability and risk
Published in Dominic Reeve, Andrew Chadwick, Christopher Fleming, Coastal Engineering, 2018
Dominic Reeve, Andrew Chadwick, Christopher Fleming
Coastal regions have always been a popular place for commerce, recreation and habitation. In many countries, land adjacent to the sea is much more valuable than inland. However, low-lying coastal plains are subject to flooding and cliffs are vulnerable to erosion. The prospect of accelerating sea level rise and storminess associated with climate change has heightened public awareness of the hazards faced by those living and working in coastal areas. Economic and social pressures have led to the construction of defences to protect against flooding and erosion. There is a high degree of uncertainty in the conditions that may be experienced by a coastal structure and strong economic pressure to restrict the cost of defences. As a result, defences are typically designed to withstand conditions of a specified severity (for example, the storm conditions encountered once every 50 years on average), judged to provide an appropriate balance between cost on one hand and the level of protection on the other.
Mega-urbanisation on the coast
Published in Mark Pelling, Sophie Blackburn, Megacities and the Coast, 2014
Sophie Blackburn, Marques César
The hazards affecting any given megacity depend upon the geographical location and physical characteristics of the city in question. Flood risk, for example, is greatest in cities that are either in close proximity to major rivers or are susceptible to storm surges — and even more so if these coincide (Prasad et al. 2009, Dasgupta et al. 2009). Elevation is another strong predicator of coastal flood risk, and coastal plains may or may not be sufficiently raised above sea level to mitigate exposure to coastal flooding as well as near-or medium-term projections for sea level rise due to climate change. Deltaic settings tend to be particularly vulnerable for this reason also, although Manila and Mumbai are examples of non-deltaic but nonetheless very low-lying exposed cities. Some additional factors that contribute to heightened exposure to current and future risks in coastal megacities are outlined in Box 1.1.
Management of urban waterways in Melbourne, Australia: 1. current status
Published in Australasian Journal of Water Resources, 2021
Barry T Hart, Matt Francey, Chris Chesterfield
The Melbourne region consists of flat basalt rock plains in the west, stretching northeast, and dissected by the Werribee, Maribyrnong, and Plenty rivers. Much of the Yarra Valley, which stretches from the Great Dividing Range to Port Phillip Bay, is underlain by Silurian sedimentary rocks with the lower stretches of the river contained to the north by the basalt plains. A broad flat coastal plain, much of it underlain with Pleistocene sand sheets, extends southeast from the foothills to the shores of Port Phillip and Western Port Bays, containing the lower reach of the Bunyip River (MMBW 1971; Presland 2008; VEAC 2011; Lancaster 2020). The main urban area lies in a low-lying basin traversed by rivers and smaller creeks, and due to the relative flatness of the area, much was flood prone and proved difficult to drain (Dingle and Rasmussen 1991).
Source-to-sink system for peat accumulation in marginal basins of the South China Sea with the Qiongdongnan Basin as an example
Published in Australian Journal of Earth Sciences, 2021
Z.-X. Li, Y. Li, D.-D. Wang, P.-L. Wang, G.-C. Zhang, H.-Y. Liu, Y. Liu, X.-J. Li, G.-Z. Song
Autochthonous and allochthonous peat, land-source dispersed organic matter deposition and three levels of convergence constituted a complex coal-series source-to-sink system. There are three main characteristics (or system components) including material homogeneity: (1) the total organic matter was homologous, namely it was suitable for development and plant growth, regardless of autochthonous accumulation; (2) allochthonous accumulation; or (3) dispersed organic matter. The alluvial plain and delta-coastal plain (Figure 15) were the ‘source subsystem’ of the source-to-sink for peat material. The subsystem consists of an alluvial sedimentary system and various subfacies, a fan/braided river delta sedimentary system and various subfacies. The microenvironment units, such as floodplain and interdistributary depression, were the first peat mire environmental units to develop and provide peat material sources. The processes of organic matter migration include insitu vertical accumulation, moved to a relatively fixed area via long-distance dispersion drift and transported with other mixed substances. The aggregation forms include in situ vertical accretion accumulation, being moved away from the plant-growing area, and being carried by flowing water to a relatively fixed area for accumulation, long-distance dispersion drift through canal flow and channel flow, and being deposited in deeper water basins with other mixed materials.
Geotechnical Reconnaissance of the 2016 ML6.6 Meinong Earthquake in Taiwan
Published in Journal of Earthquake Engineering, 2018
Chi-Chin Tsai, Shang-Yi Hsu, Kuo-Lung Wang, Hsuan-Chih Yang, Wei-Kuang Chang, Chia-Han Chen, Yu-Wei Hwang
Figure 3 shows the topographical and geological maps of the Tainan area, with information on the active faults and the locations of the epicenters in recent disastrous earthquakes. The Tainan area can be divided into two main topographical regions, namely, the coastal plain and foothills. Different features of geological structure exist in these two regions. The coastal plain region exposes Holocene sedimentary deposits as its main feature. The Holocene sedimentary deposits consist of silt, clay, and sand with a thickness ranging from 16 to 36 m [Sun et al., 1964, 1970]. The relatively fine sediment is transported from the Central Range of Taiwan after the weathering of shale, slate, and mudstone. These soils are typical sedimentary materials of the southwestern plain of Taiwan. The rock formations beneath the sedimentary deposits are dominated by alternations of sandstone, mudstone, and shale. Conversely, the foothill region exhibits a more complicated feature because of the southward propagation of the oblique convergence between the Luzon Arc (the Philippine Sea plate) and the Chinese continental margin (the Eurasian plate). Therefore, the foothill region, located in the active fold–thrust belt of the Taiwan mountain range, would result in a high seismic hazard. The recent earthquakes, such as the 2011 Jiasain earthquake, 2012 Wutai earthquake, and 2016 Meinong earthquake, all resulted from the foothill region and caused considerable damage to buildings, lifelines, bridges, and levees.