The change of global environment and the rapid development of economy have led to the increase of natural disasters, which have become one of the most serious environmental problems in modern human society. Facing the grim situation of natural disaster risk prevention and control, human society should be built strongly enough to deal with natural disaster risks. On the basis of "building a resilient society to reduce natural disaster risks", this paper focuses on analyzing the exact meaning of resilience, and interprets the connotation, composition and structure of natural disaster-resilient society through integrated hazard defense, damage recovery and emergency governance. The index system and quantitative characterization method of the natural disaster-resilient society was established to evaluate the situation of a natural disaster resilient-society in the case area. According to the differences between urban and rural areas, we designed pathways to build a natural disaster-resilient society. Then a theory paradigm of the natural disaster-resilient society, including concept-structure-index-approach, is systematically constructed. It is an inevitable option for human to build a natural disaster-resilient society, which is highly consistent with the sustainable socio-economic development. The research aims at promoting a comprehensive response to natural disaster risks, exploring ways to build a "stronger, safer and more sustainable" natural disaster-resilient society, supporting the transformation of national disaster prevention and reduction strategies, and implementing the "Nine Key Areas and Weak Links Projects".

Understanding the influencing factors and controls of rainstorm-induced floods, which have caused tremendous losses of human lives and national economy, is a pressing need for flood risk management in China. Based on the meteorological disaster census data of counties in China, hourly precipitation data at 2420 stations, statistical yearbook, terrain data and other data, the authors (1) investigated the spatiotemporal pattern of flood impacts in China over the period from 1984 to 2007 using trend analysis techniques and (2) explored the driving factors of the spatiotemporal pattern by adopting the geospatial statistical analysis tool (Geodetector). This study considered the spatiotemporal patterns and their interplays among county-level flood impacts (i.e., flood-induced mortality rate, proportion of population affected, and economic loss in percentage), disaster-formative environmental factors (i.e., population density, urban population percentages, average elevation, river density, average slope, and average distance to the seashore), and extreme precipitation characteristics (i.e., annual average volume and duration of extreme rainfall). The results show that: (1) there were no consistent temporal trends of extreme rainfall characteristics over the study period across China. (2) The frequencies of flood disasters in the Yangtze and Pearl rivers and southeast coastal areas increased significantly, but the casualties over these regions decreased. (3) Flood-induced casualties, proportion of population affected and economic loss in percentage increased in Northwest China; and meteorological factors, disaster-formative environment factors such as geographical conditions and social economy, and geographical conditions contribute mostly to the proportion of population affected, flood-induced death and economic loss in percentage. These results indicate that more attention should be paid to improving the flood control capacity of small or medium-sized cities in the inland river basins, especially in Northwest China, and we should recognize the important roles that disaster-formative environment plays in triggering flood losses.

The accumulation processes of loess in Shandong Province record atmospheric circulation changes in eastern China, which is significant in revealing the varied characteristics of East Asian monsoons and palaeoenvironmental change. In this study, the parameterized end-member modelling analysis of grain-size distributions is used to discuss the sedimentary characteristics, transport dynamics and environmental significance for a loess section in Zhangqiu, Shandong Province. The results indicated that: (1) The optically stimulated luminescence (OSL) ages of the Zhangqiu section ranged from 0.26 to 42.24 ka, suggesting that sediments have mostly deposited since the late Pleistocene. (2) The grain size components of the sediments in this section were divided into five end members: EM1 represents the mixed clay component of pedogenesis and transported sediment, EM2 represents the fine silt component transported by the high-altitude westerly wind over long distance, EM3 represents material that settles as floating dust, EM4 is the main material source of the profile, which represents the silt component transported by low-altitude suspension under local wind systems, and EM5 represents short-distance suspended materials under dust storm conditions. Change in the EM5 component is a good indicator of winter monsoon intensity change, and has recorded all climate fluctuation events since the late Pleistocene. (3) According to the climatic proxies such as the grain-size end-member content, low frequency magnetic susceptibility (χ_lf) and chromaticity (a^*), combined with the results of OSL, this effectively indicated the stage change and differences of the sedimentary environment in the Zhangqiu section since the late Pleistocene and reflected the regional response to global climate change.

Traditional methods for estimating evapotranspiration are mostly based on local scales. For data-scarce basins where ecological hydrology has undergone dramatic changes, a land surface process model that fully considers the spatial variability of the underlying surface of the watershed provides a new method of performing continuous actual evapotranspiration simulations over a long time series and at a large scale. Taking the Ebinur Lake basin as the research area, the variable infiltration capacity (VIC-3L) model was used to simulate the hydrological processes from 1960 to 2017 and explore the spatial and temporal variations in actual evapotranspiration in the study area. Additionally, the wavelet analysis method was used to analyze the multiscale characteristics of the five meteorological elements and the simulated values of actual evapotranspiration in the study area. The following results were obtained: (1) The runoff Nash-Sutcliffe efficiency (NSE) coefficients of the VIC at the Wenquan and Bole stations were 0.09 and 0.23, respectively, and the simulation results were satisfactory. Specifically, the simulated value and theoretical calculated value of the actual evapotranspiration of the VIC had an R² value of 0.80, an RMSE of 31.76 mm a^-1, an NSE of 0.32, and a relatively good simulation effect. (2) Regarding the time scale, the interannual actual evapotranspiration has presented an upward trend over the past 58 years, with the annual average actual evapotranspiration increasing at a rate of 1.03 mm a^-1. Furthermore, both monthly and daily evapotranspiration showed a single peak trend. Regarding the interdecadal changes, the actual evapotranspiration from May to July showed a downward trend in the 1990s and in the early 21st century, and an upward trend in the 1970s, while no significant change in tother months. (3) In terms of spatial distribution, the actual evapotranspiration generally showed strong evapotranspiration in high altitude areas and their surroundings. From spring to summer, the area with strong evapotranspiration shifted from the northwest to southeast. The spatial distribution of annual actual evapotranspiration is consistent with that in spring and summer. (4) A wavelet analysis identified 1 to 4 significant periods in the time-frequency domain for the actual evapotranspiration and meteorological elements in the study basin. Over a certain period, the average wind speed, average temperature, and sunshine hours changed ahead of the actual evapotranspiration while the annual precipitation and relative temperature lagged behind the actual evapotranspiration changes. Affected by precipitation, the actual evapotranspiration had a "strong-weak" transition in 1965 and 2003 with a period of 1 a; and affected by relative humidity, the actual evapotranspiration had a "strong-weak" transition in 1965 and 2008 with a period of 2-4.5 a.

Stable isotope in tree rings are effective proxies for the study of climate change and environmental evolution. Coupling analysis of stable isotope records of tree rings can reveal the spatiotemporal variation characteristics and interactions of carbon, water and nitrogen in forest ecosystems, and reflect the physiological effects of environmental changes on plant-specific compounds. The stable nitrogen isotope ratio (δ¹⁵N) in tree rings is closely related to the environmental conditions of tree growth, and the change of ratio can indicate the dynamic characteristics of nitrogen cycle in forest ecosystem on a long-term scale, and make up for the lack of monitoring data. Herein, we reviewed the theory of the stable nitrogen isotope fractionation and measuring method, and found out the issues that need to be paid attention to in sample pretreatment and measurement. Furthermore, we synthetically stated and evaluated the reports of climate and environment evolution based on δ¹⁵N of tree-rings, and the effects of human activities on nitrogen cycle in forest ecosystem. We suggested the great potential of tree-ring δ¹⁵N in combination of the multiple isotope proxies and its development directions in the future, which should promote further studies on the spatiotemporal characteristics of nitrogen cycle in forest ecosystems.

The Toudaoguai-Tongguan section is the main source area of sediments in the Yellow River and has the largest vegetation restoration rate in China. Subsequently, the rapid restoration of vegetation has had significant effects on the runoff and sediment transport processes. In this paper, the vegetation restoration characteristics, and the influencing factors and their effects on runoff and sediment processes in different landform units in the Toudaoguai-Tongguan section were analyzed based on the MOD13Q1 Normalized Difference Vegetation Index (NDVI) data using the statistical and trend analysis techniques. And then, the future vegetation development trend in this area was predicted. The results suggest that the vegetation exhibits a significant increasing trend (p < 0.05) in 82.87% of the study area, and the semi-humid loess hilly and gully zones have the largest vegetation restoration rate. Slope gradient and precipitation have different effects on the vegetation restoration in different landform units. With the increase of precipitation, the correlation between NDVI and annual precipitation in the Toudaoguai-Tongguan section is lessened. In the context of vegetation restoration, precipitation is still the major factor influencing the main river runoffs in the middle reaches of the Yellow River, whereas the sediment load is affected by both precipitation and NDVI, and the sediment concentration exhibits a relatively strong negative correlation with NDVI. With the increase of vegetation coverage, the amount of soil erosion in the watershed decreases, and the river sediment load exhibits a decreasing trend. The contribution rate of the amount of soil erosion to the sediment load varies between 39%-88%. Based on the vegetation restoration potential and vegetation restoration rate, it was predicted that the mean values of NDVI in the Toudaoguai-Tongguan section in 2020, 2030, 2040, and 2050 would be 0.68, 0.75, 0.79, and 0.80, respectively.

The eastern segment of the China-Mongolia-Russia economic corridor is situated in the overlap region of the southeast margin of Eurasia permafrost region and the southern border of the tree line, where fragile frozen ground and ecosystems have been maintained. In this study, we analyzed the spatiotemporal distribution and annual change of frozen ground, leaf area index (LAI), and the vegetation green-up data in the eastern China-Mongolia-Russia economic corridor from 2000 to 2015 based on the MERRA-Land data product, GLOBMAP LAI, and MODIS EVI dataset. The main controlling environmental factors of the green-up date and the status of vegetation growth in the different periods over a year were calculated by grey correlation analysis, and then the response of vegetation growth in typical areas to the freezing-thawing changes of the frozen ground was analyzed. Some conclusions can be drawn as follows. (1) In the past 16 years, permafrost and seasonal frost in the eastern China-Mongolia-Russia economic corridor was persistently and significantly degraded, which was mainly reflected by the early thawing and delayed freezing of the frozen ground in time, and manifested as the disappearance of permafrost and the uplift of the lower limit of seasonal frost in the southern isolated permafrost, and the thickening of the active layer in the southern continuous permafrost in space. (2) In about 48% of forest areas, the onset day of frozen ground melting is the main factor affecting the start of vegetation greening season. The growth situation of vegetation in forest areas is altered by the soil water from thawing frozen ground and the hydrothermal mechanisms of peatland. (3) With the transition from forest and peatland to meadow or farmland, the frozen ground degrades and in turn further facilitates the fade of peatland. Exploring the synergetic relationship between the degradation of frozen ground and the ecological environment is helpful to identify the vulnerable regions of degrading frozen ground and the sensitive regions of the ecological environment under the influence of climate warming and human activities.

Unmanned Aerial Vehicle (UAV) has been developed to obtain high-precision, high-resolution and three-dimensional (3D) dynamic of glacier surface, which is helpful for revealing the movement and melting of glaciers, so it has become an important technology for glaciology researches. Because the high-resolution image data can be used to effectively identify the detailed features on the surface of the debris-covered glaciers, this study employed the pyramid image set combined with the least square matching (LSM) method to track the feature points of 3D displacement field. We acquired digital orthophoto map (DOM) and digital surface model (DSM) by UAV mapping at the lower part of Gongba Glacier, Mt. Gongga, on June 9 and October 17, 2018. Feature points were extracted and tracked to obtain a 3D glacier surface displacement field, which suggests that the mean surface displacement velocity was 7.51 cm/d and the ablation was over 11 cm/d at the glacier tongue. This study provides effective reference for monitoring glaciers and glacial related hazards in steep terrain regions and unreachable mountainous areas.

It is predicted that many regions will witness higher frequencies of drought events under global climate change, which could pose a threat to crop yield and water security. Therefore, the development of efficient and reliable methods for agricultural drought prediction is crucial. This study used the Standardized Precipitation Index (SPI) based on monthly precipitation at a 6-month time scale as an indicator of meteorological drought. The Joint Standardized Soil Moisture Index (JSSI) was used to assess the comprehensive situation of agricultural drought and was derived by combining the Standardized Soil Moisture Index (SSI) over 1-, 3-, 6-, 9-, and 12-month time scales based on monthly root zone soil moisture. Using the antecedent SPI and the persistent JSSI as predictors, the Meta-Gaussian (MG) model was applied to predict agricultural drought in China from June to August in 1961-2015. The Brier Skill Score (BSS) and Nash-Sutcliffe Efficiency Coefficient (NSE) were adopted for the evaluation of the prediction performance of the MG model. The results showed that the JSSI was capable of capturing both emerging and prolonged agricultural droughts in a timely manner, which is significant for agricultural drought monitoring. The spatial distribution of predictions of severe agricultural droughts with the 1- to 3-month lead by the JSSI for June to August in 2010 and 2014 resembled the corresponding observations for most parts of China. Moreover, the areas with a predicted higher probability of JSSI falling below -0.5 corresponded well with areas that experienced agricultural drought according to observed data (JSSI ＜ -0.5). The BSS and NSE results confirmed that the MG model was able to provide reliable predictions of agricultural drought for June to August in most parts of China. The prediction of JSSI from June to August by the MG model with the 1-month lead showed that the proportions of the total area with BSS ≥ 0.5 were 0.714, 0.642, and 0.640, respectively, whereas the proportions of the total area with NSE ≥ 0.5 were 0.903, 0.829, and 0.837, respectively. However, the MG model performed poorly in desert areas, including southern Xinjiang, western Qinghai and western Inner Mongolia, which may have been due to the extremely arid conditions of these regions with soil water mostly related to condensation water rather than rainfall. The results of this study can provide scientific basis for agricultural drought monitoring, early warning, and decision-making in China.

Climate change since the last deglaciation period is an important topic of Quaternary paleoclimate research. Eolian Holocene paleosols (S₀) and last glacial loess (L₁) on the western Loess Plateau margin have high sedimentation rates and provide valuable materials for the study of East Asian monsoon climate change since the last glacial deglaciation. Here we report high-resolution environmental magnetic records spanning the last 16 ka for the whole S₀ and the uppermost L₁ from the Hepingzhen section in the western Chinese Loess Plateau. Environmental magnetic results suggest that the magnetic properties of the Hepingzhen loess section are dominated by fine-grained magnetite, including superparamagnetic (SP), single-domain (SD), and fine pseudo single-domain (PSD) magnetite particles. The magnetic susceptibility and frequency dependent magnetic susceptibility records show identical variability during the last 16 ka. This consistent variability suggests that they are both influenced by content of pedogenic fine-grained (SP, SD, and fine PSD) magnetite particles, which is similar to the loess accumulations on the eastern Chinese Loess Plateau. Therefore, the magnetic susceptibility and frequency dependent magnetic susceptibility records of the Hepingzhen loess section can be also used to infer the soil pedogenic intensity and summer monsoon precipitation that dominates regional pedogenesis, as the case for the eastern Chinese Loess Plateau. The summer monsoon rainfall variation inferred from the Hepingzhen loess magnetic susceptibility and frequency dependent magnetic susceptibility records is consistent with that inferred from South China stalagmite oxygen isotope data during the last 16 ka. Both the western Chinese Loess Plateau and South China precipitation is suggested to be substantially lower during the last glacial period than in the Holocene. Precipitation was high during the BØlling-AllerØd Warming (BA, 15-13 ka BP), and low during the Younger Dryas (YD, ~12 ka BP). The highest precipitation occurred in the early Holocene (~11 ka BP), with a long-term decreasing trend from early to late Holocene. Combining a detailed land-sea comparison, we suggest that the variation of East Asian monsoon precipitation between 16 ka and 11 ka was affected by combined solar radiation and regional temperature of the northern hemisphere, while the long-term summer monsoon precipitation during the last 11 ka was dominated by a decreasing trend in solar radiation.

Asian summer monsoon (ASM), one of the key elements of the global climate system, strongly affects food production and security of most people over Asia. However, the characteristics and the forcing drivers of the ASM system at decadal to centennial time scales remain unclear. To address these issues, we report four 1500-a long climate model simulations based on the Community Earth System Model (CESM), including full-forced run (ALLR), control run (CTRL), natural run (NAT), and anthropogenic run (ANTH). After evaluating the performances of the CESM in simulating ASM precipitation, a 10-100 bandpass filter is applied to obtain the decadal-centennial signals in ASM precipitation. The main conclusions are as follows: (1) the variation of ASM intensity shows significant decadal to centennial periodicities in the ALLR, such as ~15, ~25, ~40 and ~70 years. (2) The major spatial-temporal distributions of ASM precipitation in the ALLR show an external forced mode and a climate internal variability mode. (3) The leading forced mode of ASM precipitation is mainly affected by natural forcing over the past 1500 years and characterizes a meridional spatial 'triple' mode. In the NAT (solar irradiation and volcanic eruptions), the substantial warming (cooling) over the western tropical Pacific enhances (or reduces) the SST gradient change in the tropical Pacific and modifies the ASM rainfall distribution. Our findings contribute to a better understanding of the ASM in the past and provide implications for future projections of the ASM under global warming.

Exploring the influence mechanism of expansion for urban areas on thermal environment is significant for improving urban ecological environment. In this study, nighttime light (NTL) can be regarded as an evidence of urban development. Based on Landsat remote sensing data, DMSP/OLS nighttime light data and NPP/VIIRS nighttime light data of Xiamen, Zhangzhou and Quanzhou in southern Fujian during 1996-2017, this study applied the overall coupling model and coordination model to discuss the spatio-temporal coupling and coordination relationship between urban development and land surface temperature (LST) distribution. Additionally, the spatial response law was analyzed by standard deviation ellipse, bivariate spatial autocorrelation and landscape index. The results show that during 1996-2017, the spatial distribution patterns of LST and NTL show that urban development is closely related with factors such as geographical location and terrain. In the western inland areas with high elevations, forests are obviously concentrated with relatively low LST, while in the eastern plain areas, more urban areas are distributed with relatively high LST. In the three cities, the overall coupling situation of NTL and LST is constantly strengthening, and the proportion of coordination for NTL and LST is gradually increasing. In the early stage of urban development, the influence of NTL on LST is hysteretic. In the late stage, the influence of NTL on LST is in advance. There is a positive correlation between NTL and LST, and a spatial spillover effect is obvious. The correlation coefficient and bivariate spatial autocorrelation Moran's I value gradually increase, indicating that NTL has an increasing influence on the change of LST. The HH (High-High)-type and LL (Low-Low)-type agglomeration areas continue to expand. Influenced by the trend of integrated development of the three study cities, HH-type agglomeration area is gradually concentrated in regions connecting the cities, such as Xiamen, Jinjiang, Shishi and central urban area of Zhangzhou. The influence of urban development on LST is related to the development condition of itself. Compared with Zhangzhou and Quanzhou, NTL has a more significant influence on the LST in Xiamen. The study results provide a scientific guidance for the optimization of thermal environment in the three cities of southern Fujian.

Evapotranspiration is a key variable and key process in global water cycle, and it is crucial for understanding how anthropogenic and climate changes have impacts on terrestrial water cycle. In the last decade, global vegetation changes are dramatic, reflected by land use and land cover changes and increase in leaf area index. It remains unclear how these changes influence terrestrial evapotranspiration processes. This study uses a coupled evapotranspiration and gross primary product model (PML-V2) that is run at 500 m and 8-day resolutions across the globe to investigate the impacts of vegetation changes on spatial pattern and dynamics of evapotranspiration in the period of 2003-2017. We found that evapotranspiration across the globe has increased noticeably because of vegetation changes, which is characterized by clear regional and non-regional patterns. Transpiration has strongly increased in the central and northern parts of North America, Europe, eastern China, southern Africa, and eastern and northern Australia. Under different land cover types, shrubs and cropland have been influenced strongly, and their impact is stronger in the post-2012 period than that in the pre-2012 period. The recent total increase from these two land cover types amounts to about 0.41 ×10³ km³ a^-1, which is about 8 times of natural annual runoff from the Yellow River Basin. The results from this study can help improve the understanding of how vegetation changes caused by recent land use and land cover changes influence terrestrial water cycle and the potential local and regional climate change.

Digital terrain analysis (DTA) is one of the most important contents of research on geographical information science (GIS). However, when a digital elevation model (DEM) is used, many problems arise in DTA geomorphological studies. For instance, current DTA research focused on morphology, phenomenon and modern surface rather than the mechanism, process and underlying terrain. Thus, current DTA research needs to be transformed from the study of landform morphology to the study of landform process and mechanism. On this basis, this study summarised the current research status of geomorphology-oriented DTA and systematically reviewed and analysed the research on geomorphology, terrain modelling, terrain derivative calculation and other terrain analysis methods. The investigated studies showed that with the help of DEM data, DTA research has the advantage of carrying out geomorphology studies from the perspective of surface morphology. However, DTA research has inherent defects in data expression and analysis patterns. Thus, breakthroughs must be achieved in basic theories and key technologies to transform DTA research from phenomenon to mechanism, from morphology to process and from terrain to landform. At present, the development of research on earth science has reached a critical stage wherein DTA research should focus on the discussion of geomorphology. This study proposes several prospects of geomorphology-oriented DTA from the aspects of value-added DEM, terrain derivatives and their spatial relations and macro-terrain analysis. The study of DTA by using DEM is at a critical period along with the issue on whether the current GIS technology can truly support the development of geography. The research idea of geomorphology-oriented DTA is expected to be an important area of exploration and practice in GIS.

The lake environment in the Zoige Basin of the Tibetan Plateau persisted for a long time in the Quaternary. It represents a great turning point of environmental change over the eastern Tibetan Plateau when the basin was dissected, the lake disappeared and the Yellow River course formed. The ages of these important events are very complicated and therefore still controversial, which requires further research and discussion. This paper provides an overall review and perspective of these issues. An in-depth study of the accumulation of the palaeoflood deposits, chronology and hydrology will facilitate the establishment of a continuous sequence of palaeoflood events of the Yellow River on the Zoige Basin. The direct evidence of the extinction of the palaeo-lake and the appearance of the course of the Yellow River drainage basin will be obtained by identification of the stratigraphic unconformity between the earliest palaeoflood deposit and the palaeo-lake deposit. The age of these remarkable events can be achieved by using AMS- ¹⁴C and OSL dating methods. In combination with the analysis of environmental change, especially the evolution of geomorphology and hydro-climatology, this paper reveals the mechanisms of the dissection and the formation of the Yellow River course, and the disappearance of the palaeo-lake. Our latest investigation indicates that extraordinary palaeoflood events occurred during OSL age 13590±1200 a to 12980±1090 a along the Maqu reach of the Yellow River in the downstream of the Zoige Basin. The floodwater came from the melting of mountain glaciers surrounding the basin during the Bolling-Allerod warm phase of the last deglacition. This means that the palaeo-lake had disappeared and the course of the Yellow River had formed through the Zoige Basin. These results are of great significance in understanding the formation of the Yellow River course, and enriching the theory of environmental evolution over the Tibetan Plateau.