News

RILS study helps policymakers develop flash drought mitigation and risk management strategies

Dr Shuo WANG, Member of the Research Institute for Land and Space (RILS) and Assistant Professor of the Department of Land Surveying and Geo-Informatics at PolyU, and his research teammates find that flash droughts do not appear to be occurring more frequently in most regions of the world, just coming on faster. Approximately 33.64−46.18% of flash droughts develop within 5 days for the period 2000−2020, and there is a significant increasing trend in the proportion of flash droughts with the 5-day onset time globally. Compared with traditional, slowly developing droughts, flash droughts evolve with a relatively fast depletion of soil moisture that may cause an imbalance of ecosystems and agricultural systems.   Flash droughts are most likely to occur in humid and semi-humid regions, including Southeast China, Southeast Asia, East Asia, Amazon Basin, Eastern North America, and Southern South American. Thus, the increasing flash drought risk is overlooked, without any early warning and emergency response measures, posing serious threats to ecosystem protection and sustainable agriculture development. Atmospheric aridity creates a perfect condition for the occurrence of flash droughts, and the joint influence of soil moisture depletion and atmospheric aridity further enhances the rapid onset of flash droughts. In other words, low soil moisture combined with high vapor pressure deficit accelerates the decline in soil moisture through land–atmosphere feedbacks. Thus, Southeast China with strong land– atmosphere coupling is most vulnerable to flash droughts.   The new study contributes to a deeper understanding of the rapid onset development and driving mechanism of flash droughts. Identification of flash drought-prone regions and global hot spots can help policymakers and stakeholders develop flash drought mitigation and risk management strategies. Furthermore, comprehensive assessment of onset development timescales of flash droughts provides insights into the implementation of flash drought forecasts and early warning systems.   The study has been published in Nature Communications at https://doi.org/10.1038/s41467-022-28752-4

Research projects led by RILS members received ECF funding in 2021-22 exercise

Two research projects led by RILS members, Sr Prof. Charles WONG and Dr Shuo WANG, received over HK$2.4 million funding in total from the Environment and Conservation Fund (ECF) in the 2021-22 funding exercise. The ECF was set up by the Government in 1994 for funding educational and research projects on environmental and conservation matters. Research and Technology Demonstration Projects awarded by the ECF will contribute in a direct and practical way towards environmental improvement and conservation of the local environment, or promote and encourage adoption of green technologies in Hong Kong.   Research project Project Coordinator (PC) Amount awarded A multi-source remote sensing based technique for monitoring oil spills  Sr Prof. Charles WONG HK$1,920,520 Climate-resilient planning and design for coastal stormwater drainage systems Dr Shuo WANG HK$490,600

RILS and RISUD researchers discovered a smog-aggravating chemical in Hong Kong’s air

Ozone (O3) is an air pollutant that causes eye irritation and respiratory diseases. Despite improvement of overall air quality in Hong Kong in recent years, high concentrations of ozone remain a serious problem in the city. Ozone at ground level is produced by chemical reactions involving volatile organic compounds (VOCs) and oxides of nitrogen (NOx) in the presence of sunlight. The production of ozone is initiated and sustained by radicals – highly reactive oxidants; the conventional radicals are OH, HO2 and RO2 (collectively called ROx radicals). In a field study at a coastal site in Hong Kong, a team of researchers from the Research Institute for Land and Space (RILS) and the Research Institute for Sustainable Urban Development (RISUD) discovered unprecedented concentrations of molecular chlorine (Cl2) during the autumn when ozone pollution reaches its annual peak. Cl2 was previously known to destroy ‘good ozone’ at high altitudes over the Antarctic, thus allowing cancer-causing ultra-violet sunrays to reach the Earth’s surface. In polluted areas, however, Cl2 can be a ‘new’ radical source of ozone that harms human health and vegetation. In collaboration with international scientists, the field study team found that the high Cl2 concentrations are caused by the interaction of man-made pollutants (NOx and acidic chemicals) with natural sea-spray particles. This pollution pathway is important not only for Hong Kong but also for other coastal cities and for other pollutants like PM2.5. The team’s findings can be used to adjust or refine measures that reduce ozone pollution. The study results were published recently in Nature Communications. The first author is Dr Xiang PENG, who was a PhD student at the time of this study, and the corresponding author is Prof. Tao WANG, Member of RILS and RISUD and Chair Professor in the Department of Civil and Environmental Engineering (CEE). Other contributing authors include Ir Prof. Hai GUO (Management Committee Member of RILS), Prof. Shuncheng LEE, and additional PhD students and researchers from CEE, personnel from the Hong Kong Environmental Protection Department, and scientists from the US, France, Spain, Sweden, Germany and mainland China. The study was supported by funding from the Hong Kong Research Grants Council, the Agence Nationale de la Recherche, the Swedish Research Council, and the European Research Council.

RILS research explored the unexpected occurrences of heat waves followed by heavy rainfall

According to long-term meteorological observations provided by the Hong Kong Observatory, there is a significantly increasing trend in the number of very hot days, especially in recent years. The year 2021 was the warmest on record in Hong Kong, with 11 months that were warmer than usual. Meanwhile, the annual number of heavy rain days is also increasing, with hourly rainfall records being broken several times over the last few decades. According to the newly released Hong Kong Climate Action Plan 2050, the Government is calling for urgent action to combat extreme heat and severe rainstorms because these events have been increasing in frequency and intensity under climate change, posing serious threats to human health, socioeconomic development, urban infrastructure and ecosystems in Hong Kong. Dr Shuo WANG, Member of the Research Institute for Land and Space (RILS) and Assistant Professor, Department of Land Surveying and Geo-Informatics at PolyU, and his research teammates have looked into the issue.  Dr WANG’s research explored the unexpected occurrences of heat waves followed by heavy rainfall. Such compound extreme events could exacerbate the damage caused by the combination of different types of extreme events. The research revealed the way in which a heat wave may evolve into heavy rainfall, leading to consecutive heat waves and heavy rainfall events. These consecutive events are projected to occur more frequently under a warming climate based on gridded observations, reanalysis datasets, and model simulations. Dr WANG’s research findings revealed that out of every four heat wave events in China during the period of 1981–2005, one of the events was followed by heavy rainfall within 7 days, and Hong Kong was one of the hotspots detected across Southeast China. Furthermore, shorter and hotter heat waves were more likely to be followed by heavy rainfall. This tendency underscores the need for early warning and disaster preparedness for the occurrence of subsequent rainstorms when a short-duration but high-intensity heat wave has been observed. The research findings have significant implications for Hong Kong as the emerging climate-related disasters have been receiving increasing attention from the public.   The research results have been published in Geophysical Research Letters (https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL094831)  

RILS research team partners with government and industry testing a new land reclamation technique

Led by Ir Prof Jian-hua YIN from the Department of Civil and Environmental Engineering, a research team of the Research Institute for Land and Space (RILS) has developed an innovative technique for land reclamation using horizontal band drains to aid vacuum preloading to facilitate reuse of dredged sediment as fill material. A laboratory-scale physical model test has been successfully conducted at PolyU to demonstrate the principles and effectiveness of the technique. The model test is supported by a Research Impact Fund (HK$9,876,600) entitled “Study of Super-fast Large-area Economical Marine Reclamations for Housing and Infrastructural Developments in the Guangdong-Hong Kong-Macau Greater Bay Area” from the Research Grants Council. A prototype field trial has recently started in a testing pit (base size of 12 m x 8 m and depth of 3.5 m) in Tung Chung in collaboration with Civil Engineering and Development Department of the Government, AECOM, and Build King-Samsung C&T Joint Venture to prove the practicality and constructability of the technique in the field. The outcome of the field trial will provide a vital reference for sustainable marine reclamation in Hong Kong and will make significant academic advancement in solving soft ground problems.

Associate Director of RILS conferred as Fellow of the American Association of Geographers

Prof. Qihao WENG, Associate Director of RILS, Chair Professor and Global STEM Scholar of the Department of Land Surveying and Geo-Informatics at PolyU, has been conferred recently as Fellow of the American Association of Geographers (AAG) for his significant contributions to advancing geography.  Prof. WENG and his colleagues developed a methodology for estimating temperatures with satellite-derived measures of vegetation that is now applied widely throughout a wide range of fields.  He has also helped lead the field of remote sensing at the AAG and beyond.

Two RILS research projects received over HK$9.6 million from the Research Grant Committee

The Research Grant Committee (RGC) announced the funding results of the Collaborative Research Fund (CRF) in 2021/22 and Second Round One-off CRF COVID-19 and Novel Infectious Diseases (NID) Research Exercise earlier this year. Two research projects led by RILS management committee members, Sr Prof. Charles WONG and Ir Prof. Hai GUO, received over HK$9.6 million grant in total. Research project Project Coordinator (PC) Amount awarded RGC CRF 2021/22 Research Project Grant Study of Carbon Sequestration in Hong Kong’s Vegetation: from Present to Future Prediction under Climate Change Sr Prof. Charles WONG HK$4,949,639 Second Round One-off CRF COVID-19 and NID Research Exercise in 2021/22 Is the usual social distance sufficient to avoid airborne infection of expiratory droplets in indoor environments? Ir Prof. Hai GUO HK$4,703,090

RILS members recognised as top two percent scientists worldwide

Stanford University has recently released an update of the list that represents the top 2 percent of most-cited scientists in various disciplines. The report was prepared by a team of experts led by Prof. John IOANNIDIS, an eminent Professor at Stanford University. RILS is honoured to have 12 of our members on the list. The updated list can be downloaded from here. Congratulations to our top scientists!

RILS scholar recognised amongst the world′s most highly cited researchers

Prof. Daniel TSANG, member of RILS, Professor in the Department of Civil and Environmental Engineering at PolyU and Visiting Professor at the University of Queensland in Australia and Chulalongkorn University in Thailand, was selected as Highly Cited Researcher 2021 in two academic fields (Engineering; Environment and Ecology) by Clarivate Analytics. The list identified the most influential scholars around the world for their exceptional research performance, determined by the publication of multiple highly cited papers that ranked in the top 1% by citations in each respective field. Approximately 6,600 researchers across the globe were named Highly Cited Researchers in 2021. Congratulations to Prof. Daniel TSANG!

Associate Director of RILS elected into The Academy of Europe (Academia Europaea)

Prof. Qihao WENG, Associate Director of RILS, Chair Professor and Global STEM Scholar of the Department of Land Surveying and Geo-Informatics at PolyU, were recently elected Foreign Member of The Academy of Europe (Academia Europaea) in its 2021 class, an European institution that aims to promote European research, advise governments and international organisations in scientific matters, and further interdisciplinary and international research. Members of the Academy are nominated and elected only by their peers. Prof. WENG has made significant contributions to the advancement of knowledge in the fields of remote sensing, GIScience, urban climatology, urban ecology, sustainability science, and geospatial AI. Congratulations to Prof. WENG!