Quanyi Qiu

A neighbor decay cellular automata approach for simulating urban expansion based on particle swarm intelligence

Simulation and quantitative analysis of urban land use change are effective ways to investigate urban form evolution. Cellular Automata (CA) has been used as a convenient and useful tool for simulating urban land use change. However, the key issue for CA models is the definition of the transition rules, and a number of statistical or artificial intelligence methods may be used to obtain the optimal rules. Neighborhood configuration is a basic component of transition rules, and is characterized by a distance decay effect. However, many CA models do not consider the neighbor decay effect in cellular space. This paper presents a neighbor decay cellular automata model based on particle swarm optimization (PSO-NDCA). We used particle swarm optimization (PSO) to find transition rules and considered the decay effect of the cellular neighborhood. A negative power exponential function was used to compute the decay coefficient of the cellular neighborhood in the model. By calculating the cumulative differences between simulation results and the sample data, the PSO automatically searched for the optimal combination of parameters of the transition rules. Using Xiamen City as a case study, we simulated urban land use changes for the periods 1992–1997 and 2002–2007. Results showed that the PSO-NDCA model had a higher prediction accuracy for built-up land, and a higher overall accuracy and Kappa coefficient than the urban CA model based on particle swarm optimization. The study demonstrates that there exist optimal neighborhood decay coefficients in accordance with the regional characteristics of an area. Urban CA modelling should take into account the role of neighborhood decay.

Spatiotemporal changes of the urban heat island of a coastal city in the context of urbanisation

This study quantitatively analysed the spatiotemporal changes of the urban heat island (UHI) of Xiamen City in the context of urbanisation, using Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) thermal images acquired on similar dates in the winter of 1987, 1992, 1997, 2002 and 2007. UHI intensity and extent were used to quantify the changes, together with landscape metrics PLAND, PD, CA, NP, P-UHI, NP-UHI, PD-UHI, etc. The results show that the winter UHI of Xiamen has become more and more striking in the past 20 years in almost all the indices used. The UHI intensity increased to over 10°C, and UHI extent and thermal patch number also increased remarkably. At the same time, UHI was more dominated and fragmented by high-grade thermal patches. In winter these UHI formed several hot spots and areas of significance, distributed along the coastline. This pattern was related to industrial zones and large infrastructure constructed in coastal areas during the rapid course of urbanisation, since both large impervious ground surfaces, large-sized and endothermic factory building roofs were the sources of these hot spots. A similar seasonal analysis was also carried out, which proved that autumn UHI was most intense in Xiamen and the change in season does not change the number of UHI areas of significance.

A Comparative Analysis on Assessment of Land Carrying Capacity with Ecological Footprint Analysis and Index System Method.

Land carrying capacity (LCC) explains whether the local land resources are effectively used to support economic activities and/or human population. LCC can be evaluated commonly with two approaches, namely ecological footprint analysis (EFA) and the index system method (ISM). EFA is helpful to investigate the effects of different land categories whereas ISM can be used to evaluate the contributions of social, environmental, and economic factors. Here we compared the two LCC-evaluation approaches with data collected from Xiamen City, a typical region where rapid economic growth and urbanization are found in China. The results show that LCC assessments with EFA and ISM not only complement each other but also are mutually supportive. Both assessments suggest that decreases in arable land and increasingly high energy consumption have major negative effects on LCC and threaten sustainable development for Xiamen City. It is important for the local policy makers, planners and designers to reduce ecological deficits by controlling fossil energy consumption, protecting arable land and forest land from converting into other land types, and slowing down the speed of urbanization, and to promote sustainability by controlling rural-to-urban immigration, increasing hazard-free treatment rate of household garbage, and raising energy consumption per unit industrial added value. Although EFA seems more appropriate for estimating LCC for a resource-output or self-sufficient region and ISM is more suitable for a resource-input region, both approaches should be employed when perform LCC assessment in any places around the world.

Landscape pattern optimization for Xianghe Segment of China’s Grand Canal

ABSTRACT Optimization of landscape patterns in urbanizing areas is important for landscape planning, thus improving regional ecological security and human sense of beauty to environment. In this study, we integrated a variety of methods to optimize landscape patterns in Xianghe Segment of China’s Grand Canal (XSCGC) based on the principles of landsenses ecology. The plan scheme consisted of a spatial configuration of key ecological elements, called one point, one axis, two cores, multicorridors, and multidemonstrations. The ecological corridor system was arranged in the plan area to reverse ecological barrier effects induced by urban infrastructure and to improve connections between landscape units. The plan area was divided into 11 ecological function zones for management, protection, and development purposes. Seven ecological control indices were proposed corresponding to an ecological core and ecological developing areas to ensure ecological security. This landscape pattern optimization scheme will help achieve harmonious development of the socio-economic and eco-environment for the plan area in the future.

Risk assessment for effective prevention and management of forest fires in Lijiang City

Forest fires threaten natural resources and human lives in many areas of the world. A rational assessment of forest fire risk is critical to reduce fire damage that threatens the sustainability of forest resources and their services. This is particularly true in Lijiang City, an important world heritage site. We assessed the grades of forest fire risk in Lijiang City based on the concept of a fire life cycle, using the probability of ignition in the pre-forest fire period, the capacity for detection and emergency rescue in the mid-forest fire period, and forest fire damage in the post-forest fire period. We used the analytical hierarchy process to analyse data on the ecology, economy, cultural resources, humanities and topography of Lijiang City, and geographic information systems (GIS) as a platform to integrate multi-source data. The results strongly agree with the records of reported forest fires between 2000 and 2011. This assessment method could be used in cities with large areas forestland that contains important resources and settlements, but without sufficient fire-fighting capacity to prevent and fight forest fires.

Ecological risk assessment based on road network development analysis of Xiamen city, China

ABSTRACT Urban road network development (RND) plays an important role in social and economic evolution. However, the unlimited expansion of roads leads to great changes in urban landscape patterns, which further affect ecosystems. To better characterize the urban ecological risk (UER) of RND, in this study, RND was considered the stressor and habitat provision the assessment endpoint in a UER assessment. According to the theory of landscape ecology, habitat quality disturbance intensity (HQDI) is used to quantify the negative effect of RND on an urban ecosystem. In particular, we aimed to explore the exposure-response function between road density and HQDI under RND stress. A case study was carried out in Xiamen City to examine this association. In terms of spatial distribution, this study showed that developed areas had the highest HQDI values, whereas low HQDI values were mostly associated with suburban areas. In addition, the probability distribution of HQDIs was uneven and the urban ecosystem showed unequal sensitivities to different types of roads. Based on a multilevel characterization of UER, results of this provide a framework to predict UER under RND stress and may enhance the ability of risk managers to develop scientifically based control measures.

Ecological risk assessment based on freshwater consumption dynamic analysis of Xiamen City, China

ABSTRACT Freshwater is the lifeline of a city. Shortages in urban water supply and ecological losses occur when freshwater supply capacity and demand are imbalanced. Therefore, systematic research on the risk of freshwater consumption in urban areas is urgently demanded. A scientific understanding of the risk of urban water consumption will contribute to the efficient use of freshwater resources and ensure the stability and sustainable development of cities. Taking Xiamen City as the study area, we evaluated the ecological risk of freshwater consumption scenarios in the years 2020 and 2030 using a multilevel characterization method for urban ecological risk, stepwise regression analysis, and a gray prediction model. The results of our evaluation show that freshwater consumption in Xiamen is highly correlated with the total population, the crop acreage, the proportion of secondary industry, and the treatment rate of domestic sewage. In the 2020 and 2030 scenarios, freshwater consumption in Xiamen City is predicted to increase. Meanwhile, with the construction of water conservancy facilities, the supply capacity of freshwater in Xiamen City will be greatly improved. Therefore, the ecological impacts of freshwater consumption in the 2020 and 2030 scenarios were at the middle and low levels. In this study, the validity of the multilevel characterization method described herein for urban ecological risk has been confirmed. However, calculation of scenario probability is a difficult problem in the framework of this method, and future research should address this issue.

Assessment of Regional Ecosystem Health—A Case Study of the Golden Triangle of Southern Fujian Province, China

Intensifying urbanization and rapid population growth in Fujian Province, China, has caused pollution of air and water resources; this has adversely impacted ecosystems and human health. China has recently begun pursuing a massive infrastructure and economic development strategy called the Belt and Road Initiative, which could potentially cause further environmental damage. Evaluations of ecosystem health are therefore a first step towards identifying the potential impacts from the development and planning sustainable development strategies in the Golden Triangle of Southern Fujian. To this end, our study analyzed landscape patterns and evaluated ecosystem health in this region. We used an index system method to develop a pressure–state–response (PSR) model for assessing the region’s ecosystem health. We found that: (1) the landscape type with the greatest area in the study region is cultivated land and there were no areas that were undisturbed by human activity; (2) the overall ecological health of the region is good, but there is distinct variation across the region. This study incorporates the landscape pattern into an evaluation of ecosystem health. Using counties as evaluation units, we provide a general evaluation index for this scale. The methods reported here can be used in complex ecological environments to inform sustainable management decisions.

Sustainability efficiency of Chinese cities involving coal-fired power plants with data envelopment analysis

ABSTRACT Coal currently accounts for nearly 70% of the energy consumption in China, and is expected to remain a vital energy source in the near future. Planning and construction of national large-scale coal-fired power plants (CFPPs) is an important aspect of China’s 12th coal industry five-year plan and the development strategy for future energy. CFPPs have large electricity generation potential and are important for maintaining energy security and structure. However, the construction and development of CFPPs leads to local ecological and environmental problems. The sustainable development of CFPPs is becoming increasingly important. The assessment of CFPP sustainable development would highlight the main problems in CFPP planning, construction, operation, and management, avoiding the adverse effects on local society, economy, ecosystems, and environment. This study demonstrated a sustainable development assessment framework for CFPPs and their regions, which concerned natural resources and environmental pollutants as the inputs and human well-being as the socio-economic output. Sustainable development would mandate lower inputs and higher well-being outputs. Using data envelopment analysis, the sustainable development efficiency of cities in CFPP regions was assessed. The results showed increases in urban sustainability efficiency for cities involving CFPPs from 1990 to 2010. Heavy water pollution and excess energy consumption were the main problems identified for urban and CFPP sustainable development. The findings of this study can be used as a reference for urban and CFPP sustainable development and provide guidance for future CFPP construction and development.

Analysis of urban heat island seasonal dynamics using landscape metrics

This study quantitatively analyzed the seasonal dynamics of urban heat island (UHI) in Xiamen City, using Landsat TM/ETM+ thermal images acquired on 5 different dates in the year 2002. Landscape metrics were utilized to quantify the changes, including PLAND, PD, CA, NP, P-UHI, NP-UHI, TA-UHI, PD-UHI etc. Results showed that, August UHI was spatially intensive in not only total area, but also the extent of dominant thermal patch classes. Spring UHI was more intensive than autumn in their counterpart months, yet more fragmented than summer UHI. Autumn UHI was the weakest in all the indices. The higher grade UHI patches, in other words, the hot spots and UHI Areas of Significance lay along the coast in spring and autumn months, while extended into inland of the urban area in summer. This was decided by the bay-typed land use pattern of Xiamen.