Environmental Degradation in the Context of Growing Urbanization: A Focus on the Metropolitan Cities of India

Spatial-Temporal Pattern and Influencing Factors of Ecological Efficiency in Zhejiang-Based on Super-SBM Method

The traditional meaning of ecological efficiency generally considers only the ratio of economic output to environmental input. This paper expands the meaning and the evaluation system of ecological efficiency from the perspective of improving people's livelihoods. Not only are the discharge of wastewater, waste gas, and solid waste included in the undesired output, but the output index also takes full account of the overall development of the economy, innovation, society and the environment from the perspective of high-quality development. Under the assumption of variable returns to scale, a super-efficiency slack-based measure model based on the undesirable output and Malmquist index is introduced to measure the spatial and temporal variation of ecological efficiency of Zhejiang Province in China, and the panel Tobit method is used to study the key factors affecting ecological efficiency. The results include the four following findings: (1) In the past 12 years, the ecological efficiency of Zhejiang Province has steadily increased, except in 2019 and 2020, when seven cities in Zhejiang Province experienced a decline or near stagnation due to the impact of the economic slowdown and the COVID-19 epidemic. (2) The ecological efficiency of Zhejiang demonstrates a severe regional imbalance, showing a high level in the northeast and a low level in the southwest. (3) Malmquist index analysis shows that the improvement of ecological efficiency in Zhejiang Province has shifted from mainly relying on the dual drivers of pure technical efficiency and scale efficiency in the early stage to relying on technological progress in the later stage. (4) Tobit regression analysis shows that industrialization structure, Theil index, and traffic activity have a significant positive effect on ecological efficiency.

Renewable Energy, Urbanization, and CO2 Emissions: A Global Test

A fixed effects regression and two-step system generalized method of moments (GMM) is used to analyze secondary data from the World Bank, covering 163 countries over the period from 2000 to 2016. The study tests the relationship between renewable energy, urbanization, and CO2 emissions. The empirical results show that urbanization has an inverted U-shaped relationship with CO2 emissions, while renewable energy consumption mitigates CO2 emissions. If causal, a 1% increase in renewable energy use leads to a 1.2% decrease in CO2 emissions. The results also show that the GDP per capita has an inverted U-shaped relationship with CO2 emissions, confirming the environmental Kuznets curve (EKC). We also found that innovation, proxied by residents’ patents, has a non-linear effect on CO2 emissions. As a policy implication, developing countries should increase the share of renewable energy in their total energy use, and promote innovative activities by increasing government spending on R&D.

Linking land system changes (1980-2017) with the trophic status of an urban wetland: Implications for wetland management

The knowledge on urban ecosystem dynamics is being increasingly felt due to unprecedented symptoms arising out of urbanization. This study is aimed to assess land use-land cover changes (LULCCs) around a wetland ecosystem using high spatial resolution CORONA and Google Basemap satellite imageries. The imageries were processed by digitizing land cover features at 1:3000 scale in ArcGIS 10.1. The imageries were classified into nine classes, and an estimation of accuracy was performed utilizing the Kappa coefficient and error matrices. The overall accuracy obtained was 94% for the 2017 dataset. The key findings indicated a loss of 23% in the wetland area from 1980 to 2017. While in the vicinity, a significant increase in green spaces (706.2%) and roads (89.4%) was observed. Morphometric analysis revealed that the wetland has lost a surface area of 10.2 ha from 1980 to 2017. The maximum length (L_max) of the wetland was reduced by 722 m while the maximum width (W_max) decreased by 78 m. Bathymetric analysis revealed that the wetland is shallow with a depth ranging from 10 to 174 cm. The Carlson's Trophic State Index (TSI) of wetland ranging from 74 to 87 indicates hyper-eutrophic waters. Overall, the loss of wetland area, together with the reduction in morphometric features, low depth, and higher trophic status speak of anthropogenic pressures that are compromising the ecological integrity of this wetland. Therefore, landscape planning and governance are of pivotal importance for the conservation and management of wetland ecosystems in this region.

Urban Expansion Simulation Based on Various Driving Factors Using a Logistic Regression Model: Delhi as a Case Study

During the last three decades, Delhi has witnessed extensive and rapid urban expansion in all directions, especially in the East South East zone. The total built-up area has risen dramatically, from 195.3 sq. km to 435.1 sq. km, during 1989–2020, which has led to habitat fragmentation, deforestation, and difficulties in running urban utility services effectively in the new extensions. This research aimed to simulate urban expansion in Delhi based on various driving factors using a logistic regression model. The recent urban expansion of Delhi was mapped using LANDSAT images of 1989, 2000, 2010, and 2020. The urban expansion was analyzed using concentric rings to show the urban expansion intensity in each direction. Nine driving factors were analyzed to detect the influence of each factor on the urban expansion process. The results revealed that the proximity to urban areas, proximity to main roads, and proximity to medical facilities were the most significant factors in Delhi during 1989–2020, where they had the highest regression coefficients: −0.884, −0.475, and −0.377, respectively. In addition, the predicted pattern of urban expansion was chaotic, scattered, and dense on the peripheries. This pattern of urban expansion might lead to further losses of natural resources. The relative operating characteristic method was utilized to assess the accuracy of the simulation, and the resulting value of 0.96 proved the validity of the simulation. The results of this research will aid local authorities in recognizing the patterns of future expansion, thus facilitating the implementation of effective policies to achieve sustainable urban development in Delhi.

Assessing the Viability of Vacant Farmhouse Market in China: A Case Study in Sichuan

Massive and rapid urbanization has led to population loss in rural areas, particularly in emerging and developing countries like China. As a result, houses in rural areas become vacant, and the house prices in cities, at the same time, skyrocket. While the research on the vacant farmhouses market (VFM) is a pressing issue for sustainable urbanization and has profound policy implications in China, few empirical studies have been conducted on analyzing the willingness of house owners and urban residents to participate in the VFM and any influencing factors—as there is no such operating market in China. To bridge the research gap, we first conducted a questionnaire-based survey on rural households and urban residents with a random sampling method in six cities in Sichuan Province, China. A total of 571 valid samples, including 284 rural households and 287 urban residents, were obtained. Based on these survey data, we then used logistic regression to estimate the influencing factors on the willingness of house owners and urban residents in renting in/out or selling/buying vacant farmhouses. The results showed that: (1) more than 60% of rural house owners and urban residents are willing to participate in a potential VFM; (2) the main influencing factors of house owners’ willingness to rent out or sell their houses include the sociodemographic characteristics of farmers (e.g., age, household income) and characteristics of the vacant houses (e.g., distance to the main roads, the status of vacant houses), while the major factors that affect the willingness of urban residents to rent in or purchase vacant rural houses are the sociodemographic characteristics of urban residents themselves (e.g., occupation), the status of the potential houses, and the perceived housing market; (3) most farmers want a regulated platform for the vacant farmhouses; urban residents pay more attention to the good natural environment in rural areas and the infrastructure and public service levels of vacant farmhouses in rural areas. This study thus showed the necessity, feasibility, and potential challenges and barriers involved in establishing a VFM in China.

Urban expansion and its impact on water security: The case of the Paraíba do Sul River Basin, São Paulo, Brazil

Increasing demand for water is one of the most challenging problems that human societies face today and has encouraged new studies to examine water security and water management. Seeking to discuss this important issue in the Brazilian context, we analyzed the impacts of urban expansion on water security in a basin located in the most populated region of Brazil. To quantify increased water demand, we combined urban sprawl and regional population increase projections. In this context, our study contributes to discussions on water security by addressing the importance of integration between water and urban planning. Simulations indicate good performance in reproducing actual water system conditions. The finding demonstrates that urban expansion in the region is mainly driven by road proximity. Urban occupation is projected to increase in 170% by 2050, increasing water demands for domestic use in 38%. Results indicate the feasibility of including landscape and socioeconomic constrains in order to obtain potential domestic water demand scenarios by using land use and land cover change modelling to assess urban expansion and population growth. For the study region, our findings suggest that although urban sprawl increases water demand, urban supply will not be compromised given the large volume of available water in the basin. However, the indirect consequences of urban sprawl, such as industrialization and agricultural intensification, may compromise the quality of this resource and require better water use management in the region.

Urban environment as an independent predictor of insulin resistance in a South Asian population

Background

Developing countries, such as India, are experiencing rapid urbanization, which may have a major impact on the environment: including worsening air and water quality, noise and the problems of waste disposal. We used health data from an ongoing cohort study based in southern India to examine the relationship between the urban environment and homeostasis model assessment of insulin resistance (HOMA-IR).

Methods

We utilized three metrics of urbanization: distance from urban center; population density in the India Census; and satellite-based land cover. Restricted to participants without diabetes (N = 6350); we built logistic regression models adjusted for traditional risk factors to test the association between urban environment and HOMA-IR.

Results

In adjusted models, residing within 0–20 km of the urban center was associated with an odds ratio for HOMA-IR of 1.79 (95% CI 1.39, 2.29) for females and 2.30 (95% CI 1.64, 3.22) for males compared to residing in the furthest 61–80 km distance group. Similar statistically significant results were identified using the other metrics.

Conclusions

We identified associations between urban environment and HOMA-IR in a cohort of adults. These associations were robust using various metrics of urbanization and adjustment for individual predictors. Our results are of public health concern due to the global movement of large numbers of people from rural to urban areas and the already large burden of diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12942-019-0169-9) contains supplementary material, which is available to authorized users.

An Overview of the Impacts of Land Use Land Cover Changes (1980–2014) on Urban Water Security of Kolkata

Urban Water Security is essential in urban planning to manage cities’ water infrastructures and strengthen their water stress resilience and adaptive capacities. Decision making, governance and socio-economic factors play important roles in achieving Urban Water Security. Kolkata is a growing megacity in a developing country, which is facing rising pressures on water-environmental provisions due to the rapid population growth and urbanization and resultant governance and infrastructural issues. This review focusses on Kolkata, which is facing critical water issues, as a case study. The study presents an overview of the urban water (in)security and its dimensions in Kolkata city, such as water consumption and distribution in the city along with the changing land use-land cover of the city area, based on the results obtained from the satellite data-based land use-land cover classification, available literature, and documents from public institutions.

The role of non-governmental organizations in residential solid waste management: a case study of Puducherry, a coastal city of India

Poorly planned and uncontrolled urbanization in India has caused a variety of negative, often irreversible, environmental impacts. The impacts appear to be unavoidable and not easily mitigable due to the mounting public health problems caused by non-segregation of solid wastes at source and their subsequent improper management. Recently in India, non-governmental organizations (NGOs) and other civil society organizations have increasingly started to get involved in improving waste management services. Municipal solid waste management being a governmental function, the contribution of NGOs in this field has not been well documented. This study highlights the activities and services of Shuddham, an NGO functioning in the town of Puducherry within the Union Territory of Puducherry in South India. The NGO program promoted much needed awareness and education, encouraged source separation, enhanced door-to-door collection, utilized wastes as raw materials and generated more job opportunities. Even though source separation prior to door-to-door collection is a relatively new concept, a significant percentage of residents (39%) in the study area participated fully, while a further 48% participated in the collection service. The average amount of municipal solid waste generated by residential units in the Raj Bhavan ward was 8582 kg/month of which 47% was recovered through active recycling and composting practices. The study describes the features and performance of NGO-mediated solid waste management, and evaluates the strengths and weaknesses as well as the opportunities and threats of this system to see whether this model can sustainably replace the low-performance conventional solid waste management in practice in the town of Puducherry. The experiences from this case study are expected to provide broad guidelines to better understand the role of NGOs and their contributions towards sustainable waste management practices in urban areas.