Ecological Losses Research Articles

Improving marine biodiversity offsetting: A proposed methodology for better assessing losses and gains

Although the limitations of implementing the mitigation hierarchy have been widely discussed in scientific literature, these studies have drawn mainly on feedback concerning terrestrial ecosystems. In the case of development projects in marine and coastal environments, certain issues must be tackled to improve existing practice. This article focuses on the methodologies used to assess both the ecological losses resulting from a development project and the ecological gains generated by an offset measure. The originality of this article is to propose a standardized, operational approach regardless of the development project and the ecosystem impacted that (i) enhances avoidance and reduction efforts and (ii) assesses biodiversity offset needs based on data available in Environmental Impact Assessments (EIAs). The proposed hybrid method combines a multi-criteria analysis of the state of the environment, inspired by the Unified Mitigation Assessment Method (UMAM), and a more accurate assessment at indicator level inspired by Habitat Equivalency Analysis (HEA). The steps of the method, from the selection of biophysical indicators to offset sizing, are described and are then applied to two EIA case studies: one related to a port extension and the other to an offshore wind farm.

Oviposition site selection by Japanese gypsy moth (Lymatria dispar japonica) in a warm-temperate secondary forest in western Japan

The larvae of Japanese gypsy moth (JGM, Lymantria dispar japonica) are highly polyphagous and considered a serious pest that cause significant ecological and economic losses in forests. Monitoring of egg masses is important to prevent large outbreaks of JGM from occurring in their native range. To investigate oviposition site selection by JGM, we analyzed the occurrence and spatial distribution of egg masses across various evergreen tree species within a secondary forest dominated by evergreen broad-leaved trees in western Japan, following a large outbreak. Egg masses were concentrated on the abaxial surfaces of the leaves of a few evergreen tree species. There was a strong preference for Camellia japonica L., on which more than 75% of the egg masses were found. Egg masses were only found on evergreen tree species with large leaves (leaf area >10 cm2 and leaf dry mass >0.1 g). The spatial distribution of egg masses were clustered at scales around 1‒2 m. For effective monitoring of JGM egg masses in warm-temperate evergreen broad-leaved forests of Japan, the abaxial surfaces of the most abundant evergreen broadleaved trees with large leaves should be checked. If egg masses are found, it is likely that nearby trees of the same species will also have egg masses. Large trees should be checked thoroughly for occurrence of multiple egg masses.

The ecological benefit–loss evaluation in a riverine wetland for hydropower projects – A case study of Xiaolangdi reservoir in the Yellow River, China

This paper presents a comprehensive analysis on the ecological benefit and loss of Xiaolangdi reservoir from its completion in 2000 to 2012. We firstly propose a three-step framework of the ecological benefit–loss evaluation for hydropower projects, in accordance with which an index system of riverine wetland ecosystem services valuation was established originally. Then we make a quantitative valuation on the change of riverine wetland ecosystem services caused by this project. Finally, the ecological benefit and loss of the project in the riverine wetland were evaluated in two aspects of positive impacts and negative impacts. The results showed that (1) the positive impacts of Xiaolangdi reservoir mainly included 9 categories of ecosystem services: flood control, ice prevention, sedimentation reduction, energy substitution, emission reduction benefit, water supply, afforestation, shipping and entertainment; the total ecological benefit of the project in the riverine wetland was 26.2058billionyuan. (2) The negative impacts of Xiaolangdi reservoir mainly included 5 categories: loss due to land submergence, heritage submergence, water and soil erosion, reservoir sedimentation and immigration; the total ecological loss of the project in the riverine wetland was 24.2167billionyuan. (3) From 2000 to 2012, the net value of ecological benefit–loss for the project was 1.9891billionyuan.

Invasion Risk in a Warmer World: Modeling Range Expansion and Habitat Preferences of Three Nonnative Aquatic Invasive Plants

AbstractBiological invasions and climate change pose two of the most important challenges facing global biodiversity. Of particular importance are aquatic invasive plants, which have caused extensive economic and environmental impacts by drastically altering native biodiversity and ecosystem services of freshwater wetlands. Here, we used the maximum entropy model, Maxent, to model the potential range expansion of three nonnative aquatic invasive plants: alligatorweed, limnophila, and giant salvinia, throughout the continental United States under current, 2030 to 2059 (2040), and 2070 to 2099 (2080) climate scenarios. Maxent is a popular method to model predicted current and future species distributions based on biogeography and climate. Alligatorweed, limnophila, and giant salvinia are noxious invaders of freshwater habitats in the southeastern United States and cause economic and ecological loss. In addition, we analyzed each species' habitat preference based on wetland type, occurrence in man-made habitats, and distance to the nearest stream to better understand what future habitats are at risk and how these species spread. Our results show that in 2040 and 2080 climate scenarios, all three species have the potential to increase their range throughout the northeastern United States and as far as New York and Massachusetts. The spatial distribution of alligatorweed was primarily determined by precipitation of the warmest quarter (15.8%), limnophila was primarily determined by precipitation of the warmest quarter (52.2%) and mean temperature of the coldest quarter (21.8%), and giant salvinia was primarily determined by the mean temperature of the coldest quarter (24.3%). All three species were found significantly more frequently in lakes and ponds than in other freshwater habits. Giant salvinia was found significantly more often in man-made wetland habitats. In order to reduce the detrimental impacts of these species, land managers in the northeastern United States should concentrate early detection and rapid response management in lakes, ponds and man-made wetland habitats.

Climate Crisis and the Cosmic Bomb: Is the American Dream an Expression of Cultural Trauma?

Abstract By combining key principles from the theories of cultural trauma and developmental trauma and applying them to the collective unconscious from an ecopsychological perspective, America's persistent dysfunctional paralysis in the face of the mounting existential threats and ongoing ecological losses attributable to human-caused climate change can be viewed as a “developmental cultural trauma disorder” rooted in our assertion of dominion over the creative/destructive forces of nature in 1945 and the concurrent use of that awesome power to create hell on Earth. The consumption-driven American Dream itself, with the artificial suburban lifestyle at its atrophied heart, is seen in this shadow-casting light as the product of collectively repressing our natural grief over our lost connection to the natural world, the world soul, and human nature itself. By becoming self-aware of where we are collectively and individually in this suppressed grieving process, and by engaging in some form of truth and recon...

Book Review: The Blue Sapphire of the Mind: Notes for a Contemplative Ecology

The Blue Sapphire of Mind: Notes for a Contemplative Ecology. By Douglas E. Christie. New York: Oxford University Press, 2013. xv + 431 pp. $29.95 (cloth).As former country girl George Eliot once remarked, To make men moral something more is requisite than turn them out grass. In current ecological crisis of our planet, questions of epistemology have arisen in literature of nature and spirituality from economics of Malcolm Young philosophy of beauty in Kathryn Alexander. In this eloquent and very personal contribution, Douglas Christie unites his passion for ancient desert monks with his contemporary love of and grief for natural in a ecology. He argues that the contemplative tradition can be seen as deeply sympathetic a strain of thought within ecological literature and poetry that places great value on place of noticing, describing, and feeling simple pleasure of physical for its own sake. Christie goes on suggest that while practice of this awareness alone may not be enough to us redress pernicious effects of our utilitarian and acquisitive culture, recovery of such capacity will almost certainly be necessary kind of sustained imaginative, ecological, and spiritual renewal that we need (p. 325).Drawing on a range of contemplative spiritual and nature writing, Christie weaves his own experiences into literary analysis structured around monastic spiritual categories help us see, inhabit, and tend world (p. xi). The first two chapters argue for common ground between contemplative spiritual writings and observant writings about natural world. Both are seeking through practices of observation: monks withdrawing holy vacuum of desert and naturalists recording ecological hardships often ignored in modem industrial experience. Confessing his own detachment from natural as a child, he draws on literature both natural and spiritual invoke attention and recover presence of sacred: We are learning again value particular places and consider more deeply what is essential and necessary in our lives (p. 27). Juxtaposing Antony and Evagrius together with Aldo Leopold and Henry David Thoreau, he explores retrieval of conscious wholeness and ethical principles of thinking like a mountain and blue presence of God on Sinai.The following chapters continue weave ecology together with specific monastic themes: Penthos acknowledges ecological loss, moving through repentance appreciation of what is left. …

Aligning restoration science and the law to sustain ecological infrastructure for the future

Ecological restoration as grounded in modern science is based on a systems perspective – it seeks to recover ecological systems characteristic of past or least‐disturbed contemporary landscapes. This requires recovery of organisms along with the ecosystem features and dynamic processes that support them. Since self‐sustainability is the goal, it also requires a landscape and environmental context that supports recovery of the system. As restoration becomes more widely practiced, so too are many specialized forms of environmental intervention, such as those associated with reducing the impacts of development, promoting recovery of endangered species, and achieving compensatory mitigation. These may be valuable and may also be informed by ecological science but they differ substantially from ecological restoration because they are not necessarily focused on recovery of a self‐sustaining living system characteristic of past or least‐disturbed landscapes. The US legal system has failed to make this distinction. Federal statutes do not explicitly define restoration and in fact do little to constrain or even guide this process; if this is not rectified, net ecological losses will continue to occur. Scientists and policy makers can add precision to the use and practice of ecological restoration and other, more specialized forms of restoration, to ensure a future that can support ecosystems and the people that depend on them.

REFLEKSI 5 TAHUN PASKA ERUPSI GUNUNG MERAPI 2010: MENAKSIR KERUGIAN EKOLOGIS DI KAWASAN TAMAN NASIONAL GUNUNG MERAPI

Ecological loss assessment at the Mount Merapi National Park (MMNP) after Mount Merapi (MM) eruption in the year 2010 has not been done before. The present study aims to estimate the ecological loss at the MMNP after 2010 eruption based on Rapid Damage Appraisal Assessment. Three steps were executed: (1) identifying and mapping damages in the MMNP using remote sensing data, (2) collecting in-situ information through field assessment, (3) estimating ecological loss assessment using economic valuation approach. Two methods of economic valuation were used, namely the change in productivity (i.e. carbon stock loss) and replacement cost (i.e. land restoration cost). The results showed that approximately of 1,242 ha (19.37%) of MMNP area was heavily damaged, 1,208 ha (18.84%) was moderately damaged, and the rest was slightly damaged. The heavy damage and the moderate damage were occurred in the forest block of resort Pakem-Turi, Cangkringan, Srumbung, Dukun, Sawangan, Selo and Kemalang. The slight damage was occurred in the forest block of resort Musuk-Cepogo, Kemalang and Selo. The ecological loss was estimated in a total of 766 Billion Indonesian rupiah consist of 747.50 Billion Indonesian rupiah from carbon stock loss and 18.5 Billion Indonesian rupiah from land restoration cost. The total ecological loss was estimated approximately 38.3 Trillion Indonesian rupiah, which was a raw estimation and considered undervalued. © 2015 GJGP UNDIP. All rights reserved.

Ecological Losses are Harming Women: A Structural Analysis of Female HIV Prevalence and Life Expectancy in Less Developed Countries

Increased inequality in life expectancies across nations due to the advent of the HIV pandemic requires rigorous investigation of gender inequalities, as women now disproportionally represent the majority of global HIV cases. While empirical examinations of women’s status on HIV prevalence and life expectancy have amassed, one under-explored area of concern is the influence of environmental decline. We fill this gap by integrating ecofeminist perspectives to inform our analysis of the direct and indirect effects of ecological losses on female health outcomes in a structural equation model of 136 less developed nations. We find that ecological losses reduce women’s longevity via increased HIV rates, hunger, and diminished health resources. Conclusions point to the importance of ecological conditions and the efficacy of incorporating ecofeminist frameworks to explain global health and gender inequalities. Palabras clave: VIH / SIDA, la esperanza de vida, el eco feminismo, perdidas ecologicas, la desigualdad de genero Resumen: El aumento de la desigualdad en la esperanza de vida entre las paises debido a la aparicion de la pandemia del VIH requiere una investigacion rigurosa de las desigualdades de genero, ya que ahora las mujeres estan representadas de forma desproporcionada en la mayoria de los casos de epidemia mundial de VIH. Si bien existe evidencia empirica sobre la situacion de la mujer en la prevalencia del VIH y la esperanza de vida, un area menos investigada y de importancia es la influencia de la degradacion del medio ambiente. Para cubrir esta falta de investigacion, este estudio utiliza la integracion de perspectivas eco feministas para analizar los efectos directos e indirectos del deterioro ecologico sobre la salud de las mujeres con un modelo de ecuaciones estructurales que analiza datos de 136 paises menos desarrollados. Encontramos que los danos o deterioros ecologicos reducen la longevidad de las mujeres a traves de un aumento de las tasas de VIH, el hambre, y una disminucion de los recursos de salud. Nuestras conclusiones apuntan a la importancia de las condiciones ecologicas y la eficacia de la incorporacion de marcos eco-feministas para explicar las desigualdades en salud y de genero a nivel mundial.

Biodiversity offsetting and conservation: reframing nature to save it

AbstractBiodiversity offsetting involves the balancing of biodiversity loss in one place (and at one time) by an equivalent biodiversity gain elsewhere (an outcome referred to as No Net Loss). The conservation science literature has chiefly addressed the extent to which biodiversity offsets can serve as a conservation tool, focusing on the technical challenges of its implementation. However, offsetting has more profound implications than this technical approach suggests. In this paper we introduce the concept of policy frames, and use it to identify four ways in which non-human nature and its conservation are reframed by offsetting. Firstly, offsetting reframes nature in terms of isolated biodiversity units that can be simply defined, measured and exchanged across time and space to achieve equivalence between ecological losses and gains. Secondly, it reframes biodiversity as lacking locational specificity, ignoring broader dimensions of place and deepening a nature–culture and nature–society divide. Thirdly, it reframes conservation as an exchange of credits implying that the value of non-human nature can be set by price. Fourthly, it ties conservation to land development and economic growth, foreshadowing and bypassing an oppositional position. We conclude that by presenting offsetting as a technical issue, the problem of biodiversity loss due to development is depoliticized. As a result the possibility of opposing and challenging environmental destruction is foreclosed, and a dystopian future of continued biodiversity loss is presented as the only alternative.

Gender, Environment and Social Transformation: A Study of Selected Villages in Himachal Pradesh

In Himachal Pradesh, 85 per cent of the female work force is in agriculture and 60 per cent of the total work force in agriculture and allied activities is female. Women are a storehouse of traditional knowledge of agriculture (cropping patterns and rotation), conservation methods, cuisines and medicinal plants. The current development scenario is changing women’s lives for the worse. The degradation of the environment and the neglect of rural household needs have a great impact on biomass-based subsistence societies, with the women bearing the brunt of such changes. This article discusses how land acquisition for industry and hydro power, the non-profitability of and loss of interest in agriculture and its consequent decline for all the above-mentioned reasons are affecting women. The article discusses why the state needs to address the displacement of women from livelihoods and also the declining social cohesion caused by reduced agriculture and reduced community feeling and increased commercialisation and penetration of the market. The article also discusses how Jan Abhiyan Sanstha (JAS) and other civil society organisations have been mobilising communities, especially women, to prevent acquisition of rich agricultural land and loss of ecology and livelihoods.

Statistical Evaluation of Shoreline Change: A Case Study from Seabrook Island, South Carolina

Seabrook Island is a barrier island approximately 28 km south of Charleston, South Carolina (SC). As a residential and resort area, Seabrook Island is important to the economic health of the Charleston, SC, region. Portions of Seabrook Island are impacted by accelerated erosion, which has been combated with engineered stabilization methods, inlet relocation, and beach nourishment. Despite stabilization attempts, localized erosion is continuing, leading to potential economic and ecological losses. We used the Digital Shoreline Analysis System (DSAS) to determine long- and short-term erosion rates on the island, focusing on natural and anthropogenic changes to the beach. We assessed beach change by comparing historical aerial photographs and satellite imagery. The use of digital imagery allows for rapid assessment of the shoreline to highlight areas experiencing change, to monitor the impacts of structural controls, and to focus site-specific field investigations. Our results show that since 1939, Seabrook has experienced erosion up to 52.4 m/yr at the north end of the island near Captain Sams Inlet that is likely related to relocations of the inlet, accretion of up to 9.0 m/yr on Seabrook Beach because of nourishment of the beach, and relatively stable conditions near the south end of the island as a result of structural control and nourishments. This method of analysis is useful to support urban planning consistent with preservation of natural resources and thus may be suitable for application and testing elsewhere.

Linear fractional-based filter as a pre-classifier to map burned areas in Mediterranean countries

Wildfires in Southern Europe burn thousands of square kilometres every year, causing extensive economic and ecological losses. Accurate mapping of fire-burned areas is a decisive factor in guiding forest management decisions. In this work a linear fractional-based filter is considered as a pre-classifier for burned area estimation from Moderate Resolution Imaging Spectroradiometer (MODIS) accurate satellite imagery. Three vegetation indices (normalized difference vegetation index, enhanced vegetation index, and global environment monitoring index) and three spectral indices specifically designed for burned area identification (normalized burnt ratio, burned area index, and burned area adapted for MODIS) have been used as inputs for the proposed filter. The filtered images were classified and the accuracy of the burned area estimates was computed by kappa () statistic. Burned area perimeters measured on the ground by global positioning system were used as reference truth. A linear Gaussian pre-classification filter was used as reference to check the burned area estimates accuracy improvements. When using the proposed fractional-type filter, an accurate estimation () of areas burned by forest fires in the four study areas located in Central Spain was achieved. The results showed that the non-local filter, used as a pre-classifier, allowed higher accuracy than the same inputs both without filtering and with the Gaussian filter ( index increased up to 30% with statistical significance). McNemar test confirmed that such accuracy improvement had statistical significance, and a statistical separability test showed that filtering increased the inter-class distance, helping to improve the latter classification. Burned areas in Central Spain were accurately mapped when the linear fractional-based filter proposed here was used as a pre-classifier.

Statistical Evaluation of Shoreline Change: A Case Study from Seabrook Island, SC

Seabrook Island is a barrier island located approximately 28 km south of Charleston, South Carolina. As a residential and resort area, Seabrook Island is important to the economic health of the Charleston, SC, region. Portions of Seabrook Island are impacted by accelerated erosion, which has been combated with engineered stabilization methods, inlet relocation, and beach nourishment. Despite stabilization attempts, localized shoreline erosion is continuing, leading to potential economic and ecological loss. We used the Digital Shoreline Analysis System (DSAS) to determine long- and short-term erosion rates on the island, focusing on natural and anthropogenic changes to the beach. Our results assessed beach change by comparing historical aerial photographs and satellite imagery. The use of digital imagery allows for rapid assessment of the shoreline to highlight areas experiencing shoreline change, to monitor the impacts of structural controls, and to focus site-specific field investigations. Our results show that since 1939, Seabrook has experienced erosion up to 52.4 m/yr at the northern end of the island near Captain Sams Inlet that is likely related to relocations of the inlet, accretion of up to 9.0 m/yr on Seabrook Beach due to nourishment of the beach, and relatively stable conditions near the southern end of the island as a result of structural control and nourishments. This method of analysis is useful to support urban planning consistent with preservation of natural resources; and thus may be suitable for application and testing elsewhere.

Assessing Landscape Ecological Risk in a Mining City: A Case Study in Liaoyuan City, China

Landscape ecological risk assessment can effectively identify key elements for landscape sustainability, which directly improves human wellbeing. However, previous research has tended to apply risk probability, measured by overlaying landscape metrics to evaluate risk, generally lacking a quantitative assessment of loss and uncertainty of risk. This study, taking Liaoyuan City as a case area, explores landscape ecological risk assessment associated with mining cities, based on probability of risk and potential ecological loss. The assessment results show landscape ecological risk is lower in highly urbanized areas than those rural areas, suggesting that not only cities but also natural and semi-natural areas contribute to overall landscape-scale ecological risk. Our comparison of potential ecological risk in 58 watersheds in the region shows that ecological loss are moderate or high in the 10 high-risk watersheds. The 35 moderate-risk watersheds contain a large proportion of farmland, and the 13 low-risk watersheds are mainly distributed in flat terrain areas. Our uncertainty analyses result in a close range between simulated and calculated values, suggesting that our model is generally applicable. Our analysis has good potential in the fields of resource development, landscape planning and ecological restoration, and provides a quantitative method for achieving landscape sustainability in a mining city.

Gender Equality and Climate Justice: A Cross-National Analysis

The purpose of this paper is to gain empirical footing on the mechanisms that drive and mitigate global warming, which is a topic of growing significance to themes of social justice. Using components of the ecological footprint, we construct a measure of each nation’s relative contributions to carbon dioxide emissions after accounting for the amount sequestered by domestic forestlands. We refer to this measure as the “climate footprint,” and construct a structural equation model to test key theorizations in the environmental sociology literature. We add to this body of work by incorporating and empirically testing ecofeminist positions that the status of women is a cause and an effect of environmental conditions. Results suggest women and the environment are interconnected dimensions of exploitation, as ecological losses weaken women’s status in nations. We also find that nations with greater female representation in governing bodies have lower climate footprints, controlling for domestic (urbanization, production) and global (world-system integration) drivers. Conclusions point to the potential for gender equality and improving the status of women worldwide to curtail climate change. Other theoretical and empirical implications are treated, including the benefits of bringing women into theories of the environment and the utility of structural equation techniques for testing hypotheses that specify direct and indirect connections among relevant predictors and the outcome.

Altitudinal patterns illustrate the invasion mechanisms of alien plants in temperate mountain forests of northern China

Alien plant invasions usually cause economic and ecological losses. Currently, exotic plants have already appeared in the understory of mountain forests that are subjected to relatively less human disturbance and are often thought of as a safe shelter for most native plants. This study aims to explore invasions patterns and underlying mechanisms in the understory of Chinese mountain forests. Sixty-three quadrats of 20m×30m were systematically set up along the elevation gradient on Mount Tai and Mount Lao, Shandong Province, China. We examined the variation in alien and native plant richness and composition along the elevation gradient to explore the invasion mechanisms of alien species in mountain forests and analyzed the relationship between alien species richness and environment factors (human disturbance, slope, aspect and canopy density) in both mountains. In contrast to native plants, which presented two different richness patterns along the elevation gradient on Mount Tai and Mount Lao, alien species richness presented a consistent decreasing tendency with increasing elevation, suggesting that mechanisms driving native and alien species richness may be different. While native plants had many specialists at high altitudes and presented an obvious change of chorological groups along the elevation gradient, most alien species distributed in high altitude areas also occurred at lower elevations. All findings indicated that the invasion process in mountain forests is from great majority of alien species that are introduced at low altitude, successively filtered out by worsening climatic conditions and decreasing anthropogenic propagule pressures along the elevation gradient, and a subset of this community spreads upward to high altitude areas. Plots with high exotic species richness where generally subject to high levels of human disturbance. We conclude that approaches of monitoring and managing alien plant species should focus on low elevation areas of mountain forests to prevent invasions of high elevation areas.

The influence of circulation weather patterns at different spatial scales on drought variability in the Iberian Peninsula

Europe has suffered several extreme weather events which were responsible for considerable ecological and economic losses in the last few decades. In Southern Europe, droughts are one of the most frequent extreme weather events, causing severe damages and various fatalities. The main goal of this study is to determine the role of Circulation Weather Types (CWT) on spatial and temporal variability of droughts by means the new multi-scalar Standardized Precipitation Evapotranspiration Index (SPEI). This study aims also to identify the main CWTs associated with winter and summer droughts over different regions of Iberian Peninsula. During the period between 1950 and 2012, the most frequent CWTs were found to be the Anticyclonic (A), Cyclonic (C), North (N) and Northeast (NE) types. The trend analysis for winter season shows a clear increase of frequency CWTs associated to dry events (A, East and Southeast) and a decrease of frequency of C and northern types while in summer a clear decrease of NE is observed. The spatial patterns of correlation between SPEI and CWT show large patterns of negative correlations with winter frequencies of A and eastern weather types, while the reverse occurs with C and western types. This feature is highlighted on a regional approach. The NE type presents negative correlations Central, Northwestern and Southwestern regions during winter and positive correlations in Eastern region during summer. In opposition, the West type presents positive correlations in all regions (except Eastern region) during winter and does not present significant correlations during summer. In general, the predominant CWT associated to winter or summer drought conditions differs greatly between regions. The winter droughts are associated mainly with high frequency of E types and low frequency of W types for all areas, while the summer drought in eastern sectors are linked with low frequency of C type, as well as the western regions are related with the N type.

Encroachment of Canals of Dhaka City, Bangladesh: An Investigative Approach

Abstract Dhaka City has been suffering from many environmental problems including flooding, water logging and other related problems. Urbanization, which is occurring very fast and with larger magnitude in Dhaka, is the intrinsic reason behind these problems. High rate of urbanization causes extensive urban area expansion and as a result canals, wetland and other water bodies are quickly vanishing from the landscape. This study shows the present physical condition of the canals; identifies the processes of canal encroachment; represents the consequences of canal encroachment. 13 canals of 50 were surveyed; local people were surveyed to identify the impact and processes of encroachment. According to this study, canals of Dhaka city are under serious threat of extinction and require immediate recovery actions. Canals are being encroached in various styles and this study identifies five: unauthorized land filling, illegal construction over canal, expansion of slum, solid waste dumping, taking advantage of lack of awareness of local people as well as government agencies. However, this study also discusses the grave consequences of canal encroachment: increasing flood vulnerability, wane of ground water recharge area and ground water level, collapse of natural drainage system, loss of local ecology and biodiversity.

Urban residential area transitions in China: patterns, trends and determinations

Profound social and physical changes have taken place in urban China since the economic reform in 1978. This study investigates the patterns and trends of urban residential area transitions and analyses the driving factors behind them. Through a detailed field survey and historical satellite imagery analysis in Chengdu, Sichuan Province, it was found that the basic urban residential unit went through a social and physical succession: from pre-1949 residential areas and work-unit compounds to commodity housing estates, then to city complexes during the last three decades. As the various kinds of residential areas coexisted during the transition period, the overall urban form appears as a mosaic-like pattern, with reduced regularity along a rural–urban gradient. The transitions were achieved at the expense of a huge loss of natural ecology and arable land and also led to overheating in the residential market. Concern is also raised about the vulnerability of living conditions in current urban China.