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Against the background of regional development, this article analyses the rise and fall of 'thin identities', which tend to be utilitarian and deployed to promote regional development. We focus on two constructed regional identities in the Greater Pearl River Delta (GPRD) in China: Pearl River Delta (PRD) and Guangdong‐Hong Kong‐Macau Greater Bay Area (GBA). We analyse the adoption of these identities through news items published in newspapers in both China's Mainland and Hong Kong. The results show that both economic and political events influence the adoption of thin identities, first PRD and then GBA. In the content analysis of news items, we investigate the pathways to their adoption and possible evolution towards thickness (broader social and cultural embeddedness) by distinguishing economic, political, social, and cultural topics. The wish of policymakers to adopt new thin identities, however, does affect the credibility of existing thick ones, a point deserving of serious consideration. [ABSTRACT FROM AUTHOR]

The impact of climate change on nearshore coastal water quality and its interaction with pollution prevention efforts (e.g., the development of green and gray water infrastructure) still lack systematic investigation. This study performed a holistic analysis of the impact of climate change on the salinity and concentrations of total nitrogen (TN), total phosphorus (TP) and chlorophyll a (Chl.a) in Shenzhen Bay between Shenzhen and Hong Kong, the two most developed megacities in South China, based on three-dimensional hydrodynamic and water quality modeling. The major study findings were as follows. First, Chl.a was the most sensitive parameter, and its bay-wide average concentration in 2100 was predicted to be approximately 13% and 46% higher than those in 2015 under mild and rapid climate change scenarios, respectively. Second, sea level rise was found to be a major driver of all four water quality parameters, while temperature and radiation mainly influenced Chl.a and precipitation mainly influenced nutrients. Third, water quality responses to climate change were highly heterogeneous over the bay. Even under a mild climate change scenario, the highest location-specific changes (2100 vs. 2015) in salinity and TN, TP and Chl.a concentrations were projected to be approximately 21%, 19%, 25%, and 65%, respectively. Fourth, changes in seasonal variation due to climate change may lead to an enhanced ecological risk of algal blooms. Finally, the effect of reducing TN and TP concentrations by proposed water infrastructure development was found to be significantly weakened (nearly 40% and 20% for TN and TP, respectively, under a mild climate change scenario), while the negative effect (i.e., increase in the Chl.a concentration) was notably accelerated. Regional cooperation is critical for protecting the water quality of the bay, particularly under climate change. The insights obtained in this study are applicable to other coastal water zones around the world with similar socioeconomic backgrounds and climatic conditions. • Chlorophyll a in the bay is more susceptible to climate change than nutrients. • Sea level rise is the major driver of the climate-induced changes in water quality. • Climatic drivers have complex interactions in influencing water quality in the bay. • Climate change may lead to an enhanced ecological risk of algal blooms in the bay. • Pollution control efforts for the bay will be notably undermined by climate change. [ABSTRACT FROM AUTHOR]

The recent Sponge City Development (SCD) policy enacted in China has attracted tremendous investment, although its role in tackling water pollution remains vague. This study investigated the impact of SCD in Shenzhen, a national pilot city for SCD, on water quality in the transjurisdictional bay between Shenzhen and Hong Kong. A system modeling approach that coupled watershed nutrient load calculations with three-dimension bay water quality simulations was adopted. The main study findings include the following. While the planned SCD approach may result in much higher load reductions in total phosphorus and biochemical oxygen demand (BOD) and a comparable reduction in total nitrogen compared with those obtained by upgrading wastewater treatment plants, the contribution from green infrastructure (23.2%, 21.1% and 17.4% for total nitrogen, total phosphorus and BOD, respectively), which is a definitive component of SCD, is much smaller than that of pipeline construction (i.e., a gray infrastructure component of SCD). The overall cost-effectiveness ranking is green infrastructure > pipeline > upgrading wastewater treatment plants. On average, SCD in Shenzhen could reduce the total nitrogen and total phosphorus concentrations in the bay by 2.4% and 20.2%, respectively, but increase the chlorophyll a concentration by 5.5% due to improved light conditions. This study represents one of the few attempts to quantitatively assess the water quality impact of the SCD policy at a regional scale. The study findings suggest that SCD emphasizing green infrastructure should be preferably adopted by small-to medium-sized cities, and SCD for an individual city may only have a local impact on water quality and needs to be harmonized with other policies within the regional context. • A transboundary pollution issue between mainland China and Hong Kong was revisited. • SCD in Shenzhen can achieve more load reductions in TN and BOD than upgrading WWTPs. • Pipeline is more important than green infrastructure (GI) in Shenzhen's SCD. • The cost-effectiveness ranking with regard to load reduction is GI > pipeline > WWTPs. • SCD needs to be jointly applied with other policies to exhibit a regional impact. [ABSTRACT FROM AUTHOR]