Title: Urban flood prediction under heavy precipitation
Journal: Journal of Hydrology
Abstract: Increasing city resilience to floods under climate change has become one of the major challenges for decision makers, urban planners, and engineering practitioners around the world. Accurate prediction of urban floods under heavy precipitation is critically important to address such a challenge as it can help understand the vulnerability of a city to future climate change and simulate the effectiveness of various sustainable engineering techniques in reducing urban flooding risks in real urban settings. Here, we propose a new model for urban flood prediction under heavy precipitation. The model divides an irregular urban area into many grid cells with no limitation on the spatial resolution as long as the DEM data of the same resolution are available. It is capable of reflecting the frequent inflow or outflow interactions among grid cells and capturing the rapid generation of surface runoff in urban areas during heavy rainfall. The model also accounts for typical characteristics of urban areas, such as large-scale impermeable surfaces and urban drainage systems, in order to simulate urban floods more realistically. In addition, the model uses both surface elevation and instantaneous surface water depth of all grid cells to dynamically determine the directions of horizontal inflow and outflow during each time step of model simulation. This enables the model to capture the reverse-flow phenomenon which is commonly seen in flat urban areas during heavy storms. By applying the proposed model for reproducing the 2016 flood in Lafayette Parish, Louisiana, we demonstrate its effectiveness in predicting real-world flood events.
Title: Projected changes in temperature, precipitation, and their extremes over China through the RegCM
Journal: Climate Dynamics
Abstract: As the second biggest economy in the world, China has been experiencing significant impacts of global climate change. Developing future projections of regional climate over China is an indispensable step for designing appropriate mitigation and adaptation strategies against future climate change. To this end, this study focuses on exploring how the regional climate over China, including the mean and extreme climate, will be affected in the context of global warming throughout this century. The RegCM model is used to develop high-resolution climate scenarios for the whole country of China driven by boundary conditions of the Geophysical Fluid Dynamics Laboratory (GFDL) model under the Representative Concentration Pathways (RCPs). RegCM performance on simulating the present climate over China is evaluated and the results indicate that it is capable of reproducing the spatial distributions of temperature and precipitation. Future projections from RegCM suggest that an increase of 2 °C in daily mean temperature is expected in China by the end of the twenty-first century under RCP4.5 while an increase of 4 °C would be seen under RCP8.5. The Tibetan Plateau is likely to expect the most substantial temperature increase as well as the most significant decrease in extreme cold climate in China. In comparison, the annual total precipitation over China is projected to increase by 58 mm/year at the end of the twenty-first century under RCP4.5 and by 71 mm/year under RCP8.5. The projected changes in precipitation show apparent spatial variability due to the influences of local topography and land cover/use.
The following paper about a new model for urban flood prediction under heavy precipitation has recently been accepted for publication by Journal of Hydrology:
Wang, X., G. Kingsland, D. Poudel, and A. Fenech. Urban Flood Prediction Under Heavy Precipitation. Journal of Hydrology, accepted on July 24, 2019.
More details will come soon once the paper is published.
The following paper about regional climatic changes over China with RegCM has recently been accepted for publication by Climate Dynamics:
Lu, C., G. Huang, and X. Wang. Projected Changes in Temperature, Precipitation, and Their Extremes over China Through the RegCM. Climate Dynamics, accepted in July 2019.
More details will come soon once the paper is published.
Title: CO2 emissions patterns of 26 cities in the Yangtze River Delta in 2015: Evidence and implications
Journal: Environmental Pollution
Abstract: As a country with the highest CO2 emissions and at the turning point of socio-economic transition, China’s effort to reduce CO2 emissions will be crucial for climate change mitigation. Yet, due to geospatial variations of CO2 emissions in different cities, it is important to develop city-specific policies and tools to help control and reduce CO2 emissions. The key question is how to identify and quantify these variations so as to provide reference for the formulation of the corresponding mitigation policies. This paper attempts to answer this question through a case study of 26 cities in the Yangtze River Delta. The CO2 emissions pattern of each city is measured by two statistics: Gini coefficient to describe its quantitative pattern and Global Moran’s I index to capture its spatial pattern. It is found that Gini coefficients in all these cities are all greater than 0.94, implying a highly polarized pattern in terms of quantity; and the maximum value for Global Moran’s I index is 0.071 with a standard deviation of 0.021, indicating a weak spatial clustering trend but strong difference among these cities. So, it would be more efficient for these cities at current stage to reduce CO2 emissions by focusing on the large emission sources at certain small localities, particularly the very built-up areas rather than covering all the emission sources on every plot of the urban prefectures. And by a combination of these two metrics, the 26 cities are regrouped into nine types with most of them are subject to type HL and ML. These reclassification results then can serve as reference for customizing mitigation policies accordingly and positioning these policies in a more accurate way in each city.