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Modelling Hydrological Consequences of Climate Change—Progress and Challenges

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Advances in Atmospheric Sciences 2005年第6期22卷 789-797页

作者： chong-yu xu Elin WIDEN Sven HALLDIN Department of Geosciences University of Oslo P. O. Box 1047 Blindern N-0316 Oslo Norway Department of Earth Sciences Uppsala University Villavagen 16 S-75236 Uppsala Sweden Nanjing Institute of Geography and Limnology Chinese Academy of Sciences

The simulation of hydrological consequences of climate change has received increasing attention from the hydrology and land-surface modelling communities. There have been many studies of climate-change effects on hydrology and water resources which usually consist of three steps：（1） use of general circulation models （GCMs） to provide future global climate scenarios under the effect of increasing greenhouse gases, （2） use of downscaling techniques （both nested regional climate models, RCMs, and statistical methods） for ＂downscaling＂ the GCM output to the scales compatible with hydrological models, and （3） use of hydrologic models to simulate the effects of climate change on hydrological regimes at various scales. Great progress has been achieved in all three steps during the past few years, however, large uncertainties still exist in every stage of such study. This paper first reviews the present achievements in this field and then discusses the challenges for future studies of the hydrological impacts of climate change.

关键词： climate change water-resources assessment water balance regional scale hydrological models review

A Framework on Fast Mapping of Urban Flood Based on a Multi-Objective Random Forest Model

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International Journal of Disaster Risk Science 2023年第2期14卷 253-268页

作者： Yaoxing Liao Zhaoli Wang Chengguang Lai chong-yu xu State Key Laboratory of Subtropical Building Science School of Civil Engineering and TransportationSouth China University of TechnologyGuangzhou510641China Pazhou Lab Guangzhou510335China Department of Geosciences University of Oslo0316OsloNorway

Fast and accurate prediction of urban flood is of considerable practical importance to mitigate the effects of frequent flood disasters in *** improve urban flood prediction efficiency and accuracy,we proposed a framework for fast mapping of urban flood:a coupled model based on physical mechanisms was first constructed,a rainfall-inundation database was generated,and a hybrid flood mapping model was finally proposed using the multi-objective random forest(MORF)*** results show that the coupled model had good reliability in modelling urban flood,and 48 rainfall-inundation scenarios were then *** proposed hybrid MORF model in the framework also demonstrated good performance in predicting inundated depth under the observed and scenario rainfall *** spatial inundated depths predicted by the MORF model were close to those of the coupled model,with differences typically less than 0.1 m and an average correlation coefficient reaching *** MORF model,however,achieved a computational speed of 200 times faster than the coupled *** overall prediction performance of the MORF model was also better than that of the k-nearest neighbor *** research provides a novel approach to rapid urban flood mapping and flood early warning.

关键词： Coupled model Designed rainfall events Multi-objective random forest(MORF)method Rainfall-inundation database Urban flood prediction

Downscaling GCMs Using the Smooth Support Vector Machine Method to Predict Daily Precipitation in the Hanjiang Basin

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Advances in Atmospheric Sciences 2010年第2期27卷 274-284页

作者：陈华郭靖熊伟郭生练 chong-yu xu State Key Laboratory o/Water Resources and Hydropower Engineering Science Wuhan University Wuhan 430072 Department of Geosciences University of Oslo PO Box 1047 Blindern NO-0316 Oslo Nomvay Radar and Avionics Institute of Aviation Industry Corporation of China Wuxi 214063

General circulation models （GCMs） are often used in assessing the impact of climate change at global and continental scales. However, the climatic factors simulated by GCMs are inconsistent at comparatively smaller scales, such as individual river basins. In this study, a statistical downscaling approach based on the Smooth Support Vector Machine （SSVM） method was constructed to predict daily precipitation of the changed climate in the Hanjiang Basin. NCEP/NCAR reanalysis data were used to establish the statistical relationship between the larger scale climate predictors and observed precipitation. The relationship obtained was used to project future precipitation from two GCMs （CGCM2 and HadCM3） for the A2 emission scenario. The results obtained using SSVM were compared with those from an artificial neural network （ANN）. The comparisons showed that SSVM is suitable for conducting climate impact studies as a statistical downscaling tool in this region. The temporal trends projected by SSVM based on the A2 emission scenario for CGCM2 and HadCM3 were for rainfall to decrease during the period 2011–2040 in the upper basin and to increase after 2071 in the whole of Hanjiang Basin.

关键词： SSVM GCM statistical downscaling precipitation Hanjiang Basin

Analysis and prediction of reference evapotranspiration with climate change in Xiangjiang River Basin, China

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Water Science and Engineering 2015年第4期8卷 273-281页

作者： Xin-e Tao Hua Chen chong-yu xu yu-kun Hou Meng-xuan Jie State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Department of Geosciences University of Oslo

Reference evapotranspiration （ETo） is often used to estimate actual evapotranspiration in water balance studies. In this study, the present and future spatial distributions and temporal trends of ETo in the Xiangjiang River Basin （XJRB） in China were analyzed. ETo during the period from 1961 to 2010 was calculated with historical meteorological data using the FAO Penman-Monteith （FAO P-M） method, while ETo during the period from 2011 to 2100 was downscaled from the Coupled Model Intercomparison Project Phase 5 （CMIP5） outputs under two emission scenarios, representative concentration pathway 4.5 and representative concentration pathway 8.5 （RCP45 and RCP85）, using the statistical downscaling model （SDSM）. The spatial distribution and temporal trend of ETo were interpreted with the inverse distance weighted （IDW） method and Mann-Kendall test method, respectively. Results show that：（1） the mean annual ETo of the XJRB is 1 006.3 mm during the period from 1961 to 2010, and the lowest and highest values are found in the northeast and northwest parts due to the high latitude and spatial distribution of climatic factors, respectively; （2） the SDSM performs well in simulating the present ETo and can be used to predict the future ETo in the XJRB; and （3） CMIP5 predicts upward trends in annual ETo under the RCP45 and RCP85 scenarios during the period from 2011 to 2100. Compared with the reference period （1961-1990）, ETo increases by 9.8%, 12.6%, and 15.6% under the RCP45 scenario and 10.2%, 19.1%, and 27.3% under the RCP85 scenario during the periods from 2011 to 2040, from 2041 to 2070, and from 2071 to 2100, respectively. The predicted increasing ETo under the RCP85 scenario is greater than that under the RCP45 scenario during the period from 2011 to 2100.

关键词： Reference evapotranspiration (ET0) Spatial-temporal variation Climate change Statistical downscaling Xiangjiang River Basin

Flood variability in the upper Yangtze River over the last millennium——Insights from a comparison of climate-hydrological model simulated and reconstruction

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Science China Earth Sciences 2023年第3期66卷 547-567页

作者： Ran HUO Hua CHEN Lu LI chong-yu xu Jingjing LI Si HONG Chesheng ZHAN Jun XIA State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Hubei Provincial Key Lab of Water System Science for Sponge City Construction Wuhan UniversityWuhan 430072China NORCE Norwegian Research Centre Bjerknes Centre for Climate ResearchJahnebakken 55007 BergenNorway Department of Geosciences University of OsloP.O Box 1047 Blindern0316 OsloNorway Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Key Laboratory of Water Cycle and Related and Surface Processes Chinese Academy of SciencesBeijing 100101China

Understanding hydrological responses to rising levels of greenhouse gases are essential for climate and impact *** is,however,often limited by a lack of long record of observational data to provide a basis for understanding the longterm behavior of the climate *** reconstructed data and(global climate and hydrological)model simulations will help us to better understand the variability of climate and hydrology over timescales ranging from decades to *** this study,we proposed an integrated approach to study flood variability in the upper reach of the Yangtze River over the last millennium to the end of the 21st *** accomplish this,we first drove hydrological models using the precipitation and temperature from four Global Climate Models(GCM),BCC-CSM1.1,MIROC,MRI-CGCM3,and CCSM4,to simulate daily discharge for the upper reach of the Yangtze River during the period of the last millennium(850–1849),historical period(1850–2005),and a future period(2006–2099).Then,we evaluated whether the modeled precipitation,temperature,and extreme discharge had statistical properties similar to those shown in the documented dry-wet periods,temperature anomalies,and paleoflood ***,we explored the extreme discharge variability using model *** results indicate that:(1)The MIROC-ESM model,differing from the other three GCM models,revealed positive temperature changes from the warm period(Medieval Climate Anomaly;MCA)to the cold period(Little Ice Age;LIA),while the temperature variability of the other models was similar to the records.(2)The BCC-CSM1.1 model performed better than the others regarding correlations between modeled precipitation and documented dry-wet periods.(3)Over most of the subbasins in the upper Yangtze River,the magnitude of extreme discharge in the BCC-CSM1.1 model results showed that there was a decrease from the MCA to the LIA period and an increase in the historical period relative to the cold period,whil

关键词： Climate change Flood variability Paleoflood records Climate-hydrological model Upper Yangtze River

Spatial Interpolation of Daily Precipitation in China:1951-2005

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Advances in Atmospheric Sciences 2010年第6期27卷 1221-1232页

作者： Deliang CHEN Tinghai OU Lebing GONG chongyu xu 李维京 Chang—Hoi HO 钱维宏 Department of Earth Sciences University of Gothenburg Gothenburg Sweden School of Geography Beijing Normal University Beijing 100875 Department of Earth Sciences Uppsala University Sweden Department of Geosciences University of Oslo Norway Laboratory for Climate Studies/National Climate Center China Meteorological Administration Beijing 100029 School of Earth and Environmental Sciences Seoul National University Korea School of Physics Peking University Beijing 100871

Climate research relies heavily on good quality instrumental data; for modeling efforts gridded data are needed. So far, relatively little effort has been made to create gridded climate data for China. This is especially true for high-resolution daily data. This work, focuses on identifying an accurate method to produce gridded daily precipitation in China based on the observed data at 753 stations for the period 1951-2005. Five interpolation methods, including ordinary nearest neighbor, local polynomial, radial basis function, inverse distance weighting, and ordinary kriging, have been used and compared. Cross-validation shows that the ordinary kriging based on seasonal semi-variograms gives the best performance, closely followed by the inverse distance weighting with a power of 2. Finally the ordinary kriging is chosen to interpolate the station data to a 18 km× 18 km grid system covering the whole country. Precipitation for each 0.5°×0.5° latitude-longitude block is then obtained by averaging the values at the grid nodes within the block. Owing to the higher station density in the eastern part of the country, the interpolation errors are much smaller than those in the west （west of 100°E）. Excluding 145 stations in the western region, the daily, monthly, and annual relative mean absolute errors of the interpolation for the remaining 608 stations are 74%, 29%, and 16%, respectively. The interpolated daily precipitation has been made available on the internet for the scientific community.

关键词： daily precipitation spatial interpolation ordinary kriging gridded data China

Optimization of Key Parameters in 622-Mb/s Amplitude Shift Keying Labeled 40-Gb/s Return to Zero Differential Phase Shift Keying Optical Switching Network

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Semiconductor Photonics and Technology 2008年第1期14卷 17-21页

作者： ZHAO Jun-yan XIN Xiang-jun yu chong-xiu xu Da-xiong Key Laboratory of Optical Communication and Lightwave Technologies Beijing University of Posts and Telecommunications Beijing 100876 CHN

Optimized are the label extinction ratio and dispersion compensation of an optical label switching transmission system,which employs 40-Gb/s return to zero differential phase shift keying(RZ-DPSK)payload labeled with 622-Mb/s amplitude shift keying(ASK)control *** our scheme,the receiver sensitivities of payload and label achieves-27.8dBm and-33.5dBm,*** transmitted over 40km,60km and 80km single mode fiber(SMF)(with dispersion compensation)respectively,the payload can be recovered with no power penalty,while the label can be recovered with less than 2dB penalty.

关键词： optical label switching RZ-DPSK/ASK extinction ratio(ER) dispersion compensation orthogonal modulation

Recent Advances in Fibrous Materials for Hydroelectricity Generation

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Nano-Micro Letters 2025年第2期17卷 109-133页

作者： Can Ge Duo xu Xiao Feng Xing Yang Zheheng Song yuhang Song Jingyu Chen Yingcun Liu chong Gao Yong Du Zhe Sun Weilin xu Jian Fang College of Textile and Clothing Engineering Soochow UniversitySuzhou 215123People’s Republic of China National Engineering Laboratory for Modern Silk Soochow UniversitySuzhou 215123People’s Republic of China State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200People’s Republic of China Institute of Functional Nano&Soft Materials(FUNSOM) Soochow UniversitySuzhou 215123People’s Republic of China Department of Electrical and Computer Engineering University of MassachusettsAmherstMA 01003USA Department of Materials Imperial College LondonSouth Kensington CampusLondon SW72AZUK College of Textile Science and Engineering Zhejiang Sci-Tech UniversityHangzhou 310018People’s Republic of China School of Materials Science and Engineering Shanghai Institute of Technology100 Haiquan RoadShanghai 201418People’s Republic of China

Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable *** generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy *** materials with unique flexibility,processability,multifunctionality,and practicability have been widely applied for fibrous materials-based hydroelectricity generation(FHG).In this review,the power generation mechanisms,design principles,and electricity enhancement factors of FHG are first ***,the fabrication strategies and characteristics of varied constructions including 1D fiber,1D yarn,2D fabric,2D membrane,3D fibrous framework,and 3D fibrous gel are ***,the advanced functions of FHG during water harvesting,proton dissociation,ion separation,and charge accumulation processes are analyzed in ***,the potential applications including power supply,energy storage,electrical sensor,and information expression are also ***,some existing challenges are considered and prospects for future development are sincerely proposed.

关键词： Hydroelectricity Fibrous material Streaming potential Ion diffusion

Mechanism Study on the Effect of Retarder on Polyurethane Setting Time Based on Molecular Simulation

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 224-231页

作者： WU yuxuan xu Wenyuan yu Tianlai JI Yongcheng School of Civil Engineering Northeast Forestry UniversityHarbin 150040China

This study identified castor oil and phosphate ester as effective retarders through setting time,tensile,and flexural tests,and determined their optimal *** mechanism by which phosphate ester affects the setting time of polyurethane was further investigated using molecular dynamics *** transform infrared spectroscopy was also employed to systematically study the physical and chemical interactions between phosphate esters and polyurethane *** results demonstrate that a 1%concentration of phosphate ester provides the most effective retarding effect with minimal impact on the strength of *** phosphate ester is added to the B component of the two-component polyurethane system,its interaction energy with component A decreases,as do the diffusion coefficient and aggregation degree of component B on the surface of component *** reduction in interaction slows the setting ***,the addition of phosphate ester to polyurethane leads to the disappearance or weakening of functional groups,indicating competitive interactions within the phosphate ester components that inhibit the reaction rate.

关键词： polyurethane retarder setting time molecular dynamics diffusion coefficient