The phenomenon of food waste has aroused great concern from the international community, and some foreign countries have regulated it by law in a comprehensive way. In China, food waste mainly occurs in the public catering industry. In the whole society, we must form a legal atmosphere of being glorious to save and shameful to waste. The occasions of food waste mainly include wedding party, "event banquet", business dinner and dinner with friends. The causes of food waste include constraints of science and technology, subjective factors of actors and inherent defects of traditional ownership system. Although there are laws concerning food waste in China, the current provisions are relatively principled and scattered, lacking systematicness and maneuverability. To regulate food waste behavior by law is the need of ensuring food security, fulfilling international obligations, saving resources, protecting ecological environment, upgrading and integrating legal norms. The food waste behavior of public legal subjects and individuals in food production, processing and consumption should be comprehensively regulated by a special law, which should be formulated by the NPC Standing Committee under the guidance of the notion of social attribute of resources and the idea of green development, through direct prohibition, tax adjustment, consumption guidance and other ways. The legal regulation should focus on food and food waste behavior.
The interaction between human beings and wild animals has a profound and complex history. Wildlife tourism has gradually been seen as a compatible medium for people to interact with nature and wild animals. Along with the increasing demand in China, the supply of wildlife-themed tourist attractions, to some extent, has disordered competition, resulting in a waste of resources. Therefore, it is necessary to sort and analyze the resource base of semi-consumptive wildlife tourist attractions in China. Selecting 574 semi-consumptive wildlife tourism attractions in China from 1906 to 2019 as objects of study, this paper analyzed the spatial and temporal distribution, evolution characteristics as well as the related influencing factors of semi-consumptive wildlife tourist attractions in China, using models such as inter-annual variability index, nearest neighbor index, geographic concentration index, the Gini coefficient and the nuclear density analysis. The results show that: (1) In terms of time, the opening time of semi-consumptive wildlife tourist attractions in China is scattered, and can be roughly divided into four stages, namely the exploration stage (1906-1948), rapid development stage (1949-1959), slow development stage (1960-1992) and high-speed development stage (1993-2019). (2) In terms of space, the attractions present a cohesive distribution, and are geographically concentrated. The development between regions is highly unbalanced. Three high-density areas have formed with Beijing, Jiangsu-Zhejiang-Shanghai and Guangzhou as cores. Overall, there are more attractions in the eastern and southern coastal areas and less in the western part of China, with a transition in central China. Over time, the cohesion form continues and geographic concentration index gradually decreases approaching the assumed average level. However, the growth between regions is increasingly unbalanced. (3) The distribution of wildlife tourist attractions is influenced by development of history and national policies concerning the protection of wildlife animals, and has a certain positive correlation with the local factors such as population, the degree of economic development and the scale of tourism development. The attractions tend to be located in areas with great regional advantages, high population density, developed economy and leading tourism development. The research conclusion provides an overall cognition of spatial and temporal distribution of semi-consumptive wildlife attractions in China and will be the scientific basis and reference for investors and relevant managers to promote the further development and planning of wildlife tourism in the future.
Rural tourism has important practical significance for optimizing the rural industrial structure, and recovering the rural economy, especially for the implementation of the rural revitalization strategy. Thus, rural tourism is not only the focus of local government and tourism enterprises, but also a hot topic in domestic and international tourism research. At the same time, with the development and popularization of the Internet, travel websites, social software and other online platforms have become important tools to obtain travel information, make travel decisions, and share travel experiences. Tourism big data provides data sources and methodological support for rural tourism research. Based on data of tourism network, this paper puts forward a method for identifying rural tourism hotspots. Taking Jiangsu province as an example, this paper uses the methods of trend surface, nuclear density estimation and hot spot analysis to explore the cold and hot patterns of rural tourism, and reveals the influencing factors of the evolution with the help of geographic detectors. The results show that: (1) The annual and seasonal changes of rural tourism heat are obvious. The annual change presents s an "S" shaped evolution track, seasonal variation is characterized by "three peaks and four valleys", but the degree of seasonal influence on different types of rural tourist attractions is slightly different. (2) The spatial structure of rural tourism in Jiangsu province experienced the evolution of "mononuclear-dual-nuclear-trinuclear" in 2009-2017, but its heterogeneity is still significant, basically maintaining the overall characteristics of "high in the south and east regions, while low in the north and west regions". The hot spots are concentrated in southern Jiangsu and gradually evolve into cold spots in the north. The evolution of spatial structure shows a trend of "expanding from the west to the north". (3) There are obvious strength differences and time variations among the influencing factors. Transportation convenience and reception capacity have always been the main influencing factors. The economic development has a significant positive impact on the early development of rural tourism, and the influence of tourism resource tends to decline. The positive influence of ecological environment and government orientation on rural tourism is increasing. Hotspot identification based on network data provides a new perspective for quantitative research of rural tourism. In terms of practicability, it is helpful to clarify the evolution characteristics of the cold and hot patterns of rural tourism so as to provide important guiding significance for rural tourism resource development and regional cooperation.
It is of great practical significance to explore the regional difference characteristics and driving mechanism of the utilization efficiency of construction land under environmental constraints. The purpose is to guide the efficient utilization of urban construction land, alleviate the contradiction between social and economic development and ecological environment in the process of rapid urbanization, as well as achieve regional coordinated development. Taking environmental pollution as an unexpected output into the evaluation system, we systematically studied the spatiotemporal differentiation characteristics, dynamic trend evolution and driving factors of urban construction land use efficiency in Fujian province from 2006 to 2016. Models adopted in this analysis include the non-expected output SE-SBM model, coefficient of variation, and GML index and gray relational model. The results showed that: (1) During 2006-2016, the utilization efficiency of urban construction land in Fujian fluctuated in a sinusoidal pattern. The input-output efficiency had always been put at the effective frontier from 2012 to 2016. It is easy to find the differences of efficiency values between regions. It can also be found that there exists a non-positive correlation between efficiency and economic development level. (2) The spatial pattern suggests that the efficiency of the eastern coastal region is higher than that of the western inland areas, which forms an obvious cluster effect. Although Zhangzhou city is located in the southeastern coastal area, its efficiency value in 2016 was still in an invalid state without a fundamental change, which further illustrates that the radiation driving role of high-efficiency cities is weak. (3) The TFP of Fujian shows a sinusoidal growth trend, and the overall development trend is good. The agglomeration scale effect caused by technological progress is the main reason for the variance in the growth rate of regional TFP. Technological factor is the key to narrow the gap in the growth rate of regional TFP. (4) Urbanization level, ecological input, government regulation, cultivated land resource endowment, R&D investment in science and technology, as well as the advanced industrial structure are the main driving factors affecting the spatiotemporal differentiation and evolution of urban construction land-use efficiency in Fujian province.
Urban vulnerability is an effective measure to evaluate urban development resilience. At present, most studies on urban vulnerability focus on the special city and use the statistical method in China, and there is no urban vulnerability assessment method that is applicable to all the regional urban agglomerations. Taking the Central Yunnan Urban Agglomeration as an example, this paper develops an assessment system of urban vulnerability from three aspects of environmental system, economic system and social system. Entropy method and back propagation neural network model are used to evaluate the urban vulnerability of the study area from 2007 to 2016. The evaluation shows that the vulnerability of this urban agglomeration has a declining trend on the whole, but there is a big difference between the urban groups, which shows an unbalanced development. The evaluation results have reference significance for the planning and resilience development of the Central Yunnan Urban Agglomeration, and provide a scientific evaluation method for the study on the comprehensive development vulnerability of urban agglomeration.
Based on national second-hand housing price monitoring data from CityRE database, spatiotemporal change characteristics of 126 resource-based cities' housing prices in China during 2011 to 2018 are analyzed in detail using descriptive statistics and GIS spatial analysis method, and its influencing factors are further revealed by Spatial Durbin Model. The results show that: (1) The average housing prices of resource-based cities in 2011 and 2018 are 4105 and 5675 yuan per square metre respectively, and average housing prices of regenerative cities, mature cities, growing cities and declining cities decrease in turn. (2) Average housing prices of resource-based cities in China fluctuated upward from 2011 to 2018 with a growth rate of 38.2%, which is lower than that of the national average housing prices. In addition, the growth rate of housing price varies across different types of resource-based cities, while mature and regenerative cities have relatively large values. (3) There are significant spatial agglomeration characteristics of housing prices and the price change in resource-based cities. Hot spots of housing prices are mainly concentrated in the eastern and central regions, while cold spots of housing prices are mainly distributed in the northeastern and western regions. (4) Spatial Durbin Model suggests that per capita GDP, per capita investment in housing development, diversity index, specialization index and industrial wastewater discharge intensity are the main factors affecting housing prices' spatial differentiation of resource-based cities in China.
Under the background of the agricultural supply-side structural reform and rural revitalization, it is critical to raise farmers' income, realize sustainable agricultural development and guarantee food security by developing multiple agriculture functions in various regions and coordinating the development of regions with different agricultural functional characteristics. The spatio-temporal differentiation of agricultural multifunctions results from the comprehensive effects of the agricultural resource endowments and the socio-economic development level and stages. This paper constructs an evaluation index system of agricultural multifunctions. Taking Shandong province as an example, this paper analyzes the spatio-temporal evolution characteristics and driving mechanisms of agricultural multifunctions at county level from 2004 to 2017 by using spatial mismatch, regression analysis and so on. The results are shown as follows: The spatio-temporal evolution characteristics of agricultural functions in the province were significantly different during 2004-2017. Among them, the agricultural products supplying function showed a growth trend of increasing first and decreasing afterwards, and its high-value areas were mainly distributed in the "half-ring" area surrounding the south-central mountainous area of Shandong province; the economic development function showed a growth trend of decreasing first and increasing afterwards, and its high-value areas were transformed from traditional agricultural areas with high proportion of agriculture to modern agricultural areas with high agricultural output value and distinctive agricultural areas which have high-value agricultural products or prosperous correlative industries such as agricultural tourism; the social security function showed a downward trend, and its high-value areas were concentrated in the grain producing areas with large farmland area per labor and the mountainous-hilly areas with distinctive agriculture; the ecological service function showed a downward trend of decreasing first and increasing afterwards, and its high-value areas were mainly distributed in mountainous-hilly areas with good ecological basement. The impact of factors on different elements of the same function differed in direction and extent, which resulted in changes of agricultural functional structure. Finally, based on the functional perspective, this paper proposes the development paths and zoning optimization strategies for agriculture in Shandong province.
Regional poverty has become the core problem of urban-rural development and income distribution imbalance in China. Taking the Western Anhui area of Dabie Mountains as a case study, based on the spatial heterogeneity pattern and dependence pattern of poverty on the township scale, selecting 20 factors from three dimensions of geographical environment, economic environment and social environment, this paper explores the influence of various factors on poverty spatial differentiation through analysis of correlation, multivariate linear regression, spatial regression and geographical weighted regression. The results show that: First, the basic pattern of spatial differentiation of poverty in Western Anhui shows that the poverty rate in the southwest and south parts of the study area is high, while that in the central and northeast regions is relatively low. The spatial dependence of poverty in Western Anhui is strong. Secondly, the results of Pearson correlation analysis show that the geographical environment, economic environment and social environment are the important factors that affect the spatial differentiation of poverty. Spatial regression and GWR regression analyses show that the average slope, the gross national product per capita of above-scale industries, the proportion of income derived from the secondary and tertiary industries to the net income, the number of beds in medical and health institutions are the core factors leading to the spatial differentiation of poverty, and their influence has strong spatial heterogeneity. Finally, geographical mechanism, economic mechanism and social mechanism are the three mechanisms of poverty spatial differentiation. The geographical environment plays a fundamental role in the formation of spatial differentiation of poverty, whose impact is profound and extensive. The economic environment and social environment, controlled by the geographical environment, affect each other. These two factors are not only an important manifestation of poverty, but also related with poverty. The results of this study can be used for reference to the geographical aim of poverty intervention.
Mixed land use advocates that the land has multiple uses and functions, which is an important way to improve the vitality of economic development and the intensive use of land. At present, mixed land use is mainly applied in urban land use evolution and planning practice. With the intensification of urban-rural interaction, the urban-rural boundary tends to be blurred, and the internal structure and function of rural residential land in urban suburbs are gradually diversified, showing significant mixed utilization characteristics. Based on this, this paper attempts to apply mixed land use to the evolution and planning of rural residential land use. On the basis of reviewing the theory of mixed land use and its application, according to the logic of "connotation characteristics-quantitative evaluation-driving mechanism-practice approach", the systematic analysis of the mixed use of rural residential land in urban suburbs was carried out, and the optimization of rural residential areas was proposed. Finally, we take Yaocun village, which is located in the suburbs of Tianjin, as an example to demonstrate the research framework proposed in this paper. The ideas and plans for the mixed land use theoretically enrich the methods and framework for the transformation of rural residential land use, and provide scientific support for the preparation of village planning and the implementation of the strategy for rural revitalization in practice.
Based on the survey data of 499 farmers in Sanming, Fujian, the method of propensity score matching was used to measure the income effects of cash compensation and post compensation for farmers. The results show that both cash compensation and post compensation have positive effects on farmers' income. The effect of cash compensation on farmers' income is insignificant, while post compensation has 55.4% and 57% net effect on farmers' total income and per capita income, respectively. Further research found that the two compensation methods had different income effects for poor and non-poor farmers. Cash compensation is not conducive to poor farmers' income, while post compensation has significant positive effects across farmers with different income. In addition, considering the basic mission of ecological forest, it is found that the net effects of cash compensation and post compensation on ecological protection are different. Therefore, scientific planning on compensation methods and compensation standards is a fundamental way to achieve the double effects of ecological protection and farmers' income increase.
Under the background of incomplete factor market and farmers' differentiation, this paper explores the internal behavior logic between different types of farmers, technical constraints of cultivated land protection and technical choices, in order to provide reference for the sustainable development of cultivated land quality in China. In this paper, probit and logit methods are used to analyze different types of farmers' willingness to choose technology, behavior logic and differences in technology selection under different constraints. The results show that: pure farmers, class I and class II households have unity in farmland protection intention, but with the increase of non-agricultural income, farmers' farmland protection intention gradually decreases. In the aspect of behavioral logic, there are significant differences in the choice of different types of farmers' cultivated land protection technology. There are asymmetry and deviation between different types of farmers' endowment characteristics and different cultivated land protection technology, which are mainly constrained by different technical attributes and risk preferences. Therefore, in the implementation and application of farmland protection technology, more consideration should be given to different farmers' endowment advantages and risk preference.
Natural resources play a vital role in the economic development of a country. Natural resources accounting has become an important natural resources management tool in recent years, and it is an important part of the natural resource governance system. Natural resources accounting is an effective way to improve the governance capacity of natural resources. SEEA 2012 and SNA 2008 play a crucial role in the theoretical research and accounting practice of natural resources. They are the important theoretical framework of natural resources accounting at home and abroad. In the new era of rapid development of informatization technology, China's balance sheet and resources accounting idea of natural resource asset management promote the construction of China's natural resource governance system and improve China's natural resource governance capacity. At present, in the theory of natural resources accounting, there is still a lack of unified understanding of the accounting framework and method, and in practice, there is also a lack of an effective accounting system. Therefore, it is necessary to systematically analyze the theoretical results of current natural resources accounting and establish the natural resources accounting system in China to guide the practice of natural resources accounting. Based on WSR methodology, this paper studies the theory and literature of natural resources accounting, and considers the establishment of China's natural resources accounting system. The main conclusions of this study are as follows: The natural resources accounting system should systematically analyze the "WSR" of natural resources accounting; based on the "WSR" analysis, the natural resources accounting consists of the national economic accounting of natural resources, the government asset management accounting of natural resources and the enterprise operation asset accounting of natural resources. The national economic accounting of natural resources is helpful for making macro-economic plan and economic decision-making, government asset management accounting of natural resources is helpful for government asset management, and enterprise asset accounting of natural resources is helpful for enterprise natural resource asset management and market element allocation. Based on WSR method, the natural resources accounting system can make wiser choices for accounting purpose, accounting framework, way of realization and accounting method. After a systematic analysis, the construction of accounting theoretical structure of natural resources accounting is helpful to improve the theory and practice, and to solve the divergence in the field of natural resources accounting research.
From the micro perspective, the driving factors of ecological land loss in urban riverside area are analyzed, especially based on the quantitative analysis of the factors with crucial influences such as policy and planning, which has important reference significance for the formulation of ecological land protection policies. In this paper, the Bayesian network model is used to integrate the neighborhood factors, natural factors, policy and planning factors that lead to ecological land loss. And the relationship between ecological land change and its driving factors is clearly illustrated by a good graphical description method. The research results show that from 2005 to 2018, about 11.0% of the ecological land in Nanjing riverside area is lost, and the stable proportion of ecological land is 89.0%. The sensitivity of ecological land protection intensity to ecological land loss is as high as 9.37%, the sensitivity of construction potential factor is 2.53%, and the sensitivity of development difficulty is only 0.21%. The effect of shoreline planning is better than that of land use planning, which indicates that the protection policy based on the function goal of ecological land should be made to ensure the long-term existence of ecological space.
Plantations in China are facing a series of issues, such as structure degradation and function reduction. Thus, it is urgently requested to implement effective measures on plantations through reasonable forest management strategies. The Moshao forest farm of Huitong ecological station, which is a typical forest ecosystem in Red Soil Hilly Region of South China, is the study area to examine the dynamics of forest area and aboveground biomass (AGB) in the next century. The landscape disturbance model named LANDIS-II was employed in this study to simulate the effects of harvesting intensities and artificial regeneration on artificial coniferous forest, artificial broad-leaved forest, and natural broad-leaved forest by six scenarios. The scenarios included low, middle, high harvest intensity and each scenario had an artificial regeneration option after harvesting. The results showed that as the harvesting intensity went heavier, the area of artificial coniferous forest decreased. Conversely, natural forest area increased. And the forest AGB decreased sharply when the harvesting intensity was high. Plantations could take advantages of artificial regeneration to remain the area and facilitate the AGB accumulation. The scheme of harvesting with 20% of plantations every 10 years and followed by artificial regeneration would basically retained the area and AGB at the initial level in the next century. Therefore, this scheme was more applicable to the long term development of the forest in the study area and helpful to achieve the forest sustainable management of Chinese fir and masson pine plantations.
Based on field monitoring and 3S technology, Qixia city in the low hilly area of Eastern Shandong province was taken as the research area. Pearson correlation, unconstrained PCA and corresponding canonical analysis (CCA) were used to study the coupling between landscape pattern and non-point source pollution at different watershed scales. The results show that: (1) The spatial variation of landscape pattern is obvious; the patches of agricultural land and construction land are relatively fragmented at the characteristic scale; and the patches of other types of land are highly aggregated. (2) The river surface source pollutants in the study area are mainly TN-based, and the main river outlet is the more polluted area. (3) The influence of landscape pattern on water quality during the wet period is greater than that of the normal water period, and TN and EC are most sensitive to the change of land use type area ratio and landscape pattern index. At different scales, water quality affected by landscape pattern and land use type is different. (4) In normal period at riverside scale, landscape that has the greatest impact on TN is the patch density, and EC is most affected by landscape edge density. At small basin scale TN is greatly affected by landscape spread, and COD is closely related to landscape diversity. The diversity of landscape on the scale of the riverbank during the wet period has the greatest influence on TN, the EC is greatly affected by the polymerization of the plaques, and the biggest factors affecting TN on the small basin scale are consistent with the flat water period, and EC is closely related to landscape spread. (5) At small basin landscape, TN is mainly affected by the density of forest land patch, TP and cultivated land dispersion are closely related to the parallel index, the abundance of water TN is significantly influenced by the forest land dispersion and juxtaposition index, TP is sensitive to the change of the average dimensionality of forest land, and EC is most influenced by grassland aggregation. Basically, the study clarified the spatial distribution characteristics of landscape pattern and non-point source pollution in the study area, and discussed the correlation between them at different scales, which provided a scientific basis for sustainable utilization of water and land resources in Qixia city.
With the effective control of point source pollution, non-point source and sewer overflow pollution becomes the main type of water pollution. Based on materials of land use, urban drainage network and so on, the basin-bay integrated water environmental model was established, and the spatio-temporal characteristics of non-point source and sewer overflow pollution in Shenzhen Bay Basin as well as its impacts on water environment were analyzed. Results showed that (1) The non-point source and sewer overflow pollution loading per unit area of COD, NH3-N and TP in rainy season was 17.21 t/km2and 10.21 t/km2, 0.17 t/km2and 0.69 t/km2, 0.04 t/km2 and 0.07 t/km2, respectively; (2) The non-point source and sewer overflow pollution was concentrated in May and August with more heavy rainfall observed in Shenzhen River Basin, Dasha River Basin and Xinzhou River Basin with larger area, steeper surface slope and more sewerage cutting projects; (3) The COD, NH3-N and TP concentrations of non-point source and sewer overflow pollution could approach 3.7, 18.2 and 8.5 times the values of water quality standards, respectively; (4) The areas where the COD, NH3-N and TP concentrations in rainy season were higher than those in dry season exceeded 40%, 60% and 65% of the total area of Shenzhen Bay, respectively.
The daily cooling rate of station was calculated based on daily minimum temperature data of 54 meteorological stations in the middle and lower reaches of the Yangtze River from 1958 to 2015. A quantitative analysis of the evolutionary characteristics and spatial changes of cold wave occurrence and development was conducted in the region. The results showed that in the past 58 years, the frequency of cold wave presented an insignificant decrease trend with an average of 1.2 times/station (P>0.05). During cold wave processing, the spatial distribution of average difference of the minimum temperature was higher in the south and lower in the north; and the extreme of average difference of the minimum temperature gradually decreased from the regional center to the surroundings. The first cold wave occurred on August 1 (Jiujiang), and the last on May 4 (Shouxian and Lu'an). The spatial distribution of the time difference was significant. The frequent cold waves occurred in winter, followed by spring and autumn.
Using the daily precipitation data of the long-term series of meteorological stations on the Qinghai-Tibet Plateau, the percentile threshold method is used to determine the extreme precipitation threshold, calculate the extreme precipitation index and analyze its spatial and temporal distribution characteristics, in order to provide reference for regional climate change prediction and disaster prevention and mitigation countermeasures. The results show that: (1) From 1961 to 2017, the annual precipitation of Qinghai-Tibet Plateau showed an upward trend, with a rate of 8.06 mm/10 a, and the average annual precipitation reached 472.36 mm. The minimum precipitation tendency rate of 78 stations is -25.46 mm/10 a, and the maximum value is 43.02 mm/10 a. The precipitation of 15.38% of the stations is decreasing, which is mainly distributed in the east and south of the plateau, and the precipitation of the remaining 84.62% of the stations is increasing. (2) The average threshold value of extreme precipitation in the Qinghai-Tibet Plateau is 23.11 mm, with error values ranging from 7.84 mm to 51.90 mm. The high value centers are located in Gongshan and Muli of Hengduan Mountains, while the low value centers are located in the northern flank of Qaidam Basin and Kunlun Mountains. (3) The extreme precipitation, the number of days of extreme precipitation and the contribution rate of extreme precipitation at all the stations in the Qinghai-Tibet Plateau show an obvious upward trend. Although the intensity of extreme precipitation is also rising, the trend is not obvious, which shows that the increase of extreme precipitation in the plateau is not caused by the intensity of extreme precipitation, but by the increase of the frequency of extreme precipitation. Although the extreme precipitation and days of extreme precipitation in the Qaidam Basin do not show a high value level, the contribution rate of extreme precipitation is larger, which suggests that although there is less precipitation, extreme precipitation events frequently occur in this area.
Drought and flood are the main agrometeorological disasters in the Democratic People's Republic of Korea (DPRK), which have great influences on the growth of the crops and directly affect grain yield. The level of agricultural production is low because of insufficient investment and poor irrigation installation. Drought and flood are prone to a reduction in grain yield in DPRK. The food security issue in DPRK is not only related to this country's domestic stability but also related to the geo-security in Northeast Asia. Therefore, understanding the spatial and temporal patterns of drought and flood is very important for preventing disasters in this country. In this study, the Tropical Rainfall Measuring Mission (TRMM) 3B43 time series dataset was used to reveal the spatial and temporal patterns of drought and flood in DPRK from 1998 to 2018. The drought and flood levels were developed by a Z-index. In addition, the trend of Z-index is tested by the Mann-Kendall (M-K) method. The result shows that the precipitation in the study area has an obvious seasonal pattern, with more than 57.29% of the rainfall concentrated in summer, and only 6.90% in winter. The precipitation in spring is slightly higher than that in autumn. Both interannual and seasonal precipitation show increasing trends during the study period. The spatial pattern of precipitation increases from the northeast to the southeast along the coastline. Generally, the regional comprehensive drought and flood levels in DPRK are normal at the national scale. Moderate drought and flood levels occur most frequently, followed by severe drought and flood, and the frequency of extreme drought and flood eventd is the lowest. The floods frequently occur in autumn, and droughts frequently occur in summer and winter. The frequency of drought and flood events appear in the north of DPRK, particularly in Hamgyeong Mountains and the Gaema Plateau. Flood intensity shows an increasing trend in spring, summer, and autumn, while drought and flood level tended to be normal in winter. The central and northern regions passed the significance of 95%. It is expected that the trend of drought and flood in DPRK will be consistent in future. The results of the study provide a unique insight for understanding the agricultural production in DPRK.
The study of various proxies of stalagmites is conducive to understand the characteristics and mechanisms of monsoon climate events comprehensively. Here, we present a high-resolution and multi-proxy stalagmite record from Yongxing Cave, Central China, spanning the interval between 65 and 35 ka B.P. based on high precision U/Th dating method and multi-proxy analyses. A total of 371 subsamples were drilled for oxygen and carbon isotopic measurements along the growth axis at a spacing of 0.5-mm-diameter carbide dental burrs. The analyses were conducted using a Finnigan MAT 253 mass spectrometer linked to a Kiel Carbonate Device at the School of Geography, Nanjing Normal University. The precision is 0.06‰ for δ18O and 0.05‰ for δ13C at the 1σ level. For the gray-level measurements, the polished surface of the studied section was scanned at a resolution of 1200 dpi using an EPSON Perfection 4990 Photo Scanner. The gray level was then obtained from the image using the Environment for Visualizing Images (ENVI 4.8) software while traversing down the growth axis. The values range between 0 and 442, with a spatial resolution of 20 μm. The experimental results show that during the period of 65-40 ka B.P., the stalagmite records of gray-level, δ13C and δ18O all presented millennial to sub-millennial changes, but the amplitude of δ13C is much smaller than that of δ18O. This indicates that the local climate indicators of δ13C, gray-level and lithology also respond to the Heinrich (H) events and Dansgaard-Oeschger (DO) events, but their sensitivities to events are different. During the H4 episode (about 40-38 ka B.P.), δ13C and the gray-level of the stalagmite showed anomalous changes. The significantly positive shift of δ13C reached an amplitude of 4.5‰ during H4, which was 2-3 times than other H events, while the gray-level presented the same characteristics to that of the DO cycles. We imply that the state of soil erosion may play an important role in such correspondence during H4. When the monsoon weakened to a certain threshold, the soil cover above the permeable cave was greatly deteriorated, thus weakening and/or preventing the infiltration ability of the soil-karst system and increasing the impurity contents in the stalagmite.
Mountain rivers are generally featured by deep-cut river valley and steep side slopes, which is prone to landslide-dammed lake and outburst floods. Taking 2018.10.10 Baige landslide-dammed lake in Jinsha river as an example, wind reworked the outburst flood sediments and developed a plenty of sand dunes at the bank of Jinsha river. This studies about aeolian dunes in the Yarlung Zangbo River, to some extent, could provide some implication for the sedimentary distinction of aeolian sand and original flood deposit, and has some significance for engineering control of aeolian dune in this region. In this paper, a slope climbing dune in the floodplain of the middle and lower reaches of Yarlung Zangbo River, we analyzed the grain size characteristics and and spatial differentiation of surface sediments on four overlapping crescent-shaped dunes of a climbing dune, named Fozhang dune in the lower Yarlung Zangbo. The results of particle size analysis show that frequency distribution curves of the surface sediment of Fozhang dune, dominated by poorly sorted medium sand, is extremely positive biased and narrowly peaked. In the case of four individual superimposed crescent-shaped dune, the coarsest and best sorted particle fraction emerges at the top of the slope. On the whole, the surface sediment of Fozhang dune has become finer and better sorted towards the crest, which results from the combined sorting of wind and gravity. The grain size characteristics of Fozhang dune is comparable to other aeolian dunes of similar genesis. However, Sahu criterion indicates that the Fozhang dune is fluvial-originated. Maybe Sahu criterion cannot identify aeolian sand of very proximal material source from river floodplain. The comparison of grain size characteristics of sand samples with those of floodplain suggests that Fozhang dune is mainly provided with sand source by materials carried by rivers.