Forest Coverage Rate Research Articles

Evaluation of land ecosystem health in Shaanxi Province, Northwest China based on PSR Model.

Based on the pressure-state-response (PSR) model and entropy method, we analyzed the health status of land ecosystem and the temporal and spatial variations from 2009 to 2017 in ten cities and one district in Shaanxi Province. The driving factors affecting the health of the land ecosystem was examined. Results showed that during 2009-2017, the overall health of the land ecosystem in Shaanxi Province was improved, which was lower during 2009-2014 and being obviously improved after 2014. The health level of land ecosystems in Xi'an, Baoji, Weinan and Hanzhong was high and with substantial variation, while that in Yan'an, Yulin, and Ankang was low and stable, decreasing in order of South Shaanxi, Guanzhong region and North Shaanxi. Overall, the pressure, state and response indices of the land ecosystem in Shaanxi Province increased during 2014-2017 with a gentle growth, which were basically flat after 2014. Those results indicated that the land ecosystem in Shaanxi Province was at a stable and healthy state. Population growth, urbanization level, fertilizer load per unit of arable land, forest coverage rate, industrial wastewater discharge compliance rate and comprehensive utilization rate of industrial solid waste were the main driving factors for the health of land ecosystems in Shaanxi. Controlling the use of fertilizers and pesticides, optimizing the structure of land use and improving land use efficiency are necessary strategies to promote the construction of ecological civilization and implement the red line of ecological protection for Shaanxi Province.

Assessment on Agricultural Drought Vulnerability and Spatial Heterogeneity Study in China.

Reducing drought vulnerability is a basis to achieve sustainable development in agriculture. The study focuses on agricultural drought vulnerability in China by selecting 12 indicators from two aspects: drought sensitivity and resilience to drought. In this study, the degree of agricultural drought vulnerability in China has been evaluated by entropy weight method and weighted comprehensive scoring method. The influencing factors have also been analyzed by a contribution model. The results show that: (1) From 1978 to 2018, agricultural drought vulnerability showed a decreasing trend in China with more less vulnerable to mildly vulnerable cities, and less highly vulnerable cities. At the same time, there is a trend where highly vulnerable cities have been converted to mildly vulnerable cities, whereas mildly vulnerable cities have been converted to less vulnerable cities. (2) This paper analyzes the influencing factors of agricultural drought vulnerability by dividing China into six geographic regions. It reveals that the contribution rate of resilience index is over 50% in the central, southern, and eastern parts of China, where agricultural drought vulnerability is relatively low. However, the contribution rate of sensitivity is 75% in the Southwest and Northwest region, where the agricultural drought vulnerability is relatively high. Among influencing factors, the multiple-crop index, the proportion of the rural population and the forest coverage rate have higher contribution rate. This study carries reference significance for understanding the vulnerability of agricultural drought in China and it provides measures for drought prevention and mitigation.

Multi-criteria analysis for mapping of environmentally sensitive areas in a karst ecosystem

Karst ecosystems are one of the ecologically sensitive areas most affected by the dramatic harmful effects of the desertification process due to their structural, geomorphologic, and ecologic characteristics. The objective of this study was to assess and mapping ecologically sensitive areas (ESAs) for monitoring desertification and improving degraded forest areas in karst ecosystems. Sensitive ecological areas were evaluated using the Mediterranean Desertification and Land Use Methodology (MEDALUS) by considering soil quality, vegetation quality, climate quality, and management quality. Three new parameters (exposed rocky surface index, soil organic carbon index, and depression area index) were added specifically to karst ecosystem were evaluated using the Analytic Hierarchic Process (AHP) to determine ecological sensitivity. The study area is Sarimsak Karstic Mountain located in Andirin, Kahramanmaras. Soil organic carbon exposed rocky surface and depression area indices were evaluated over 110 soil samples. Values of each indices were determined according to the AHP methodology. The new SQImodified map, which was generated using new indices unique to karstic ecosystems provided a more precise spatial distribution. The results indicated that 44.49% of the study area is Critical, 51.94% is Fragile, and 3.58% is Potential in terms of desertification levels. In areas identified as Critical; agricultural fields, rangelands, and rocky surfaces cover 71.54%. Urban areas were evaluated as 100% Fragile class. Forested areas were evaluated in the Fragile and Potential class. The forest cover class affects Fragile and Potential status very closely. With the increase in forest cover rate, it has reduced fragility. The most critical ESAi classification area (C3) was detected in rangelands. Specific indices should be created to provide a realistic perspective in the combat to desertification in karst ecosystems.

Key Points of Policing Work at Underground Station of High Speed Railway in Hainan International Tourism Island

The forest coverage rate of Hainan Island is more than 60%, and the forest is an important ecological support for Hainan to build an international tourism island. Aircraft and high-speed railway are the main means of carrying tourists. The high-speed railway station of Meilan Airport is located underground, so the security work is very difficult. This paper analyzes the main risks of Meilan underground station, and puts forward the Policing Work mode suitable for Meilan underground station, which combines the Policing Work with the public security work The construction of international tourism island is combined organically, and the main points of Policing Work are summarized and perfected, which provides a reference for the public security organs to perform the security of export-oriented underground stations.

Ecological Construction Mode of Soil and Water Conservation in the Three Gorges Reservoir Area

The Three Gorges Reservoir Area is an important ecological barrier and an important area of water conservation in China. Due to natural and man-made factors, the regional urbanization process is accompanied by soil erosion. In recent years, by actively implementing measures such as tree planting and afforestation, water and soil conservation projects, the forest coverage rate in the Chongqing Three Gorges Reservoir area has increased significantly, and soil erosion has been initially controlled. But the task of environmental protection in the Three Gorges Reservoir area is still arduous. This research analyzed the causes of soil erosion caused by the urban process, by collected and combed the data of soil erosion in the Three Gorges Reservoir area of Chongqing over the years. The causes of soil erosion in the Three Gorges Reservoir area caused by the urbanization process were deeply analyzed, we proposed to improve legislation and supervision; strengthen publicity and education of soil and water conservation; adopt new technology and technology and other governance countermeasures. The Three Gorges Reservoir is an important ecological barrier in the upper reaches of the Yangtze River. The control of soil erosion in the area has important ecological and social benefits for protecting the ecological environment of the Yangtze River Basin in China.

ВЛИЯНИЕ УРОВНЯ ЗАЛЕСЁННОСТИ НА ИЗМЕНЕНИЕ ЧИСЛЕННОСТИ ЛОСЯ В НЕКОТОРЫХ РАЙОНАХ КУЗБАССА

Forests are a unique environmental phenomenon, since their space serves as the fundamental basis for the life of an innumerable number of biological species. Significant integral limited territories of forests are important ecosystems of our planet and have a significant impact on climate and biological processes. Mixed or single-breed, mountain or plain, dense or well-groomed, the forest as a self-regulating system with its life cycle is directly related to the natural balance. Currently, fragmentation, degradation and loss of natural habitats of animals are recognized as serious threats to the conservation of wildlife around the world. First of all, these changes are anthropogenic in nature and directly affect forests as a sphere of existence of the animal world. This issue is updated in the works of modern domestic and foreign scientists. Fragmentation, deterioration, and destruction of natural animal habitats are major threats to global wildlife conservation. The article introduces some results of monitoring the existing data on the layout chart, exportation, and protection of hunting grounds on the territory of the Kemerovo region (Kuzbass). The data were provided by the Kemerovo Regional Department of Wildlife Protection. The article focuses on the population of large game species, e.g. elks. The research covered two municipalities, namely Krapivinsky and Topkinsky municipal districts. The study proved that monitoring data analysis can provide reliable initial assessment of the changes that happen to the hunting grounds and the local biodiversity as a result of natural and man-induced processes. A comparative analysis of game population in several economic zones of the Kemerovo region revealed a strong connection between the uneven growth and / or decrease in the animal population on the hunting grounds and the level of forest coverage. Based on the study of monitoring data, analysis of comparative material on the number of hunting species in different economic zones of the Kemerovo region revealed the existence of natural connections between uneven growth and/or reducing the number of animals on the hunting grounds, and’s forest coverage rate. The study confirms and complements the research of Russian and foreign researchers on the complex influence of anthropogenic and biological factors on changes in the parameters of the population of hunting species (elk). The obtained results contribute to modern research on the mechanisms of population regulation. To improve the efficiency of hunting resources use, it is necessary to conduct on-farm management with the introduction of new methods of land quality assessment based on forest management materials in geoinformation systems. These points fit into the prospects of our further research.

北京市4种城市功能区森林植被涵养水源功能评价及价值估算

本研究对北京市首都功能核心区、城市功能拓展区、城市发展新区和生态涵养发展区进行林分涵养水源功能评价及价值估算，旨在探究提升城市功能区森林水源涵养功能较优林分配置模式。结果表明：（1）北京市森林植被面积2009年为4.00×10⁵ hm²，2014年为4.59×10⁵ hm²，北京市NDVI平均值2009年为0.331，2014年为0.708，北京市森林植被面积总体呈增加趋势。北京市2014年林地绿化调节水量较2009年降低了近1/3，2014年水源涵养功能价值量较2009年分别减少了22.08%和8.24%。（2）生态涵养发展区水源涵养功能年平均能力最强（2.88×10⁸ m³/a），城市发展新区水源涵养功能年平均能力次之（1.72×10⁸ m³/a），而首都功能核心区水源涵养功能年平均能力相对最弱，仅1.05×10⁶ m³/a。在针叶林、阔叶林和混交林三种林分类型中，2014年混交林水源涵养功能价值量较2009年增加5.13%，而阔叶林和针叶林分别减少34.93%和55.55%。（3）培育纯林，提高森林覆盖率，对于调节水土资源和保护生态环境具有非常重要的生态意义，而从森林水源涵养功能实物量和价值量考虑，认为混交林比纯林具有更强的水源涵养功能和较优的经济价值。在城市特定的条件下，建立生态与景观相协调的人工植物群落使城市土地资源的利用达到生态、社会、经济三大效益的最佳结合，是提高城市绿地质量的关键所在。;In this study, an optimal forest configuration for water conservation function was explored, which this optimal forest configuration could guarantee the forest vegetation can be give full play to water and soil conservation function. The remote sensing image data in 2009 to 2014 of Beijing and the data of Beijing forest resources inventory of 2009 and 2014 were used to carry out the evaluation and value estimation of water conservation function of typical forest (coniferous, broad-leaved and mixed forests) with GIS software in this paper, where in capital function core area, urban function development area, new urban development area and ecological conservation development area in Beijing. The evaluated and estimated results show: (1) the forest vegetation area in Beijing was 4.00×10⁵ hm² in 2009 and 4.59×10⁵ hm² in 2014. The average Normalized Difference Vegetation Index (NDVI) in Beijing was 0.331 in 2009 and 0.708 in 2014. The forest vegetation area in Beijing presented an overall increasing trend. The regulated water volume of forest land greening in Beijing in 2014 was nearly 1/3 lower than that in 2009, and the value of water conservation function in 2014 was 22.08% and 8.24% lower than that in 2009, respectively. (2) The annual average capacity of water conservation in the ecological conservation development area is the strongest (2.88×10⁸ m³/a), followed by the annual average capacity of water conservation in the new urban development area (1.72×10⁸ m³/a), while the annual average capacity of water conservation in the capital core area is the weakest (1.05×10⁶ m³/a). Among the coniferous, broad-leaved and mixed forests, the value of water conservation function of mixed forest is increasing, and its value of this forest type increased by 5.13% in 2014 compared with that in 2009, while the value of water conservation function of broad-leaved forest and coniferous forest decreased by 34.93% and 55.55%, respectively. (3) Cultivating pure forest to increase the forest cover rate has a very important ecological significance for regulating soil and water resources and protecting ecological environment, but considering the amount and value of forest water conservation function, this study concluded that the mixed forest had stronger water conservation function and better economic value than pure forest. Under the specific conditions of the city, the artificial plant community coordinated with ecology and landscape can make the utilization of urban land resources to reach the ecological society. The best combination of the three economic benefits is the key to improve the quality of urban green space.

Poverty and Physical Geographic Factors: An Empirical Analysis of Sichuan Province Using the GWR Model

Given the complexity of the poverty problem, efforts and policies aiming at reducing poverty should be tailored to local conditions, including cultural, economic, social, and geographic aspects. Taking the Sichuan Province of China as the study area, this paper explores the impact of physical geographic factors on poverty using the Ordinary Least Squares (OLS) Regression and the Geographically Weighted Regression (GWR) models at the county level. In total, 28 factors classified in seven groups were considered as variables, including terrain (relief degree of the land surface, altitude, and slope); vegetation (forest coverage rate); water (drainage network density); climate (temperature, annual average rainfall); and natural disaster (landslide, debris flow, and torrential flood). The 28 variables were then tested using correlations and regressions. A total of six physical variables remained significant for the OLS and GWR models. The results showed that the local GWR model was superior to the OLS regression model and, hence, more suitable for explaining the associations between the poverty rate and physical geographic features in Sichuan.

Can China’s policy of carbon emission trading promote carbon emission reduction?

Empirical evidence shows that the market-oriented trading mechanism is an important means for the Chinese government to control environmental pollution. It also has a significant effect on enterprises’ carbon technology level and low-carbon energy investment. Based on a quasi-natural experiment of China’s carbon emission trading pilots, this study adopts a difference-in-difference model to explore the effect of carbon emission trading policies on carbon emission reduction. It also examines the mediating effects of total energy consumption, technical research level, and the energy consumption structure. The results show that a carbon emission trading policy, economic development, technical research level, and opening to the outside world can significantly reduce carbon dioxide emission intensity and promote carbon emission reduction. By contrast, the industrial structure and environmental protection planning hinder the carbon emission reduction process, while the forest coverage rate has no significant effect on carbon emission reduction. Additionally, when implementing carbon emission trading policy, local governments have remained focused on reducing total energy consumption and optimizing the energy structure, but they have not actively conducted technical research.

Changes in nutrient balance, environmental effects, and green development after returning farmland to forests: A case study in Ningxia, China

Returning sloping farmland (>25°) to forest/grassland (RFTF) is an effective ecological measure for soil and water conservation. However, changes in nutrient cycles and green development are still unclear. Ningxia, in Northwestern China, began to implement RFTF in 2000. Here, we used the NUFER model to calculate the input and loss of nitrogen and phosphorus, utilization efficiency, production and consumption at food-chain scale in Ningxia for the period 1985–2015. Five aspects comprised the evaluation of green development: society, economy, resources, environment, and productivity. Results showed that forest coverage rate increased from 7.74% to 33.2%, while cropping area decreased by 6.6%. NH3 loss increased from 53,000 to 83,000 tons (56%), N2O increased from 1200 to 2300 tons (92%) and leaching loss from 18,000 to 62,000 tons (240%). Phosphorus leaching loss increased from 13,000 to 35,000 tons (130%). The environmental cost of food nitrogen per unit of production decreased from 8 to 6.7 kg/kg (19.4%). Nitrogen and phosphorus use efficiencies decreased by 4.8% and 58% in crops-animal systems, respectively, but increased by 652% and 430% in animal husbandry systems. The proportion of animal protein production increased from 18.3% to 39.0% (113%). The major source of organic waste was livestock and poultry manure and urine (70%). Indicators for achieving green development level increased from 14 to 18 (14.7%). Improving the level of scientific and technological management of aquaculture system, increasing the proportion of organic matter returned to farmlands, and paying attention to the combination of planting and breeding will effectively promote future cycling efficiency of nitrogen and phosphorus in the food chain, and the sustainability of agriculture towards green development.

Determinants of Temporary Trade Barriers in Global Forest Products Industry

Imposing temporary trade barriers (TTBs) as remedy actions against imports has become popular among global countries in recent decades. Many countries have employed these trade barriers to protect domestic firms from possible injury by unfair international trade. This study evaluated the main factors that influenced the implementation of TTBs in the forest products industry from 1995 to 2015 for two scenarios: a global and developing countries scenario; and a paper and non-paper products scenario. A two-step sample selection model was employed to assess the determinants of the decision to impose TTBs and the frequency to implement TTBs for the scenario of global and developing countries. From the perspective of forest products, determinants of applying TTBs on paper and non-paper products were examined with the probit regression. For the scenario of global and developing countries, the import, employment in agriculture, forest coverage rate, inflation, and GDP per capita were significant determinants. For the scenario of paper and non-paper products, variables of the forest area, imports, exports, GDP per capita, tariff rate, expenditure on education, and employment in agriculture were significant. The results show that a country with a large per capita GDP is more likely to file more TTBs against others. One implication is that countries should be cautious to impose TTBs, as it may cause the attention to shift from the inefficiencies of domestic forest firms to the unfair trade actions of exporters.

Environmental Protection and Sustainable Development in Ecological Functional Zones

In order to explore the impact of ecological environmental protection measures on ecological functional zones and promote the sustainable development of ecology, the ecological functional zone of a hilly region in south China is taken as the research object in this study. Combined with the data of ecological environment and land use type in the past ten years, the ecological function index (water conservation index), ecological structure status (forest coverage, grassland coverage, and ratio of wetland in waters), and ecological stress situation (ratio of cultivated land to construction land) are analyzed to reflect the ecological status of ecological functional zones. The results show that in the past ten years, the water conservation index and forest coverage rate in the studied area have been improved significantly, and the ecological condition has become better, which indicates that ecological protection measures such as returning farmland to forest and closing mountains for forest cultivation can improve the ecological environment of ecological functional zones and contribute to the sustainable development of ecology.

CHINA FOREST COVER EXTRACTION BASED ON GOOGLE EARTH ENGINE

Abstract. Forest cover rate is the principal indice to reflect the forest acount of a nation and region. In view of the difficulty of accurately calculating large-scale forest area by traditional statistical survey methods, it is proposed to extract China forest area based on Google Earth Engine platform. Trained by the enough samples selected through the Google Earth software, there are nine different random forest classifiers applicable to their corresponding zones. Using Landsat 8 surface reflectance data of 2018 year and the modified forest partition map, China forest cover is generated on the Google Earth Engine platform. The accuracy of China's forest coverage achieves 89.08%, while the accuracy of Global Forest Change datasets of Maryland university and Japan’s ALOS Forest/Non-Forest forest product reach 87.78% and 84.57%. Besides, the precision of tropical/subtropical forest, temperate coniferous forest as well as nonforest region are 83.25%, 87.94% and 97.83%, higher than those of other’s accuracy. Our results show that by means of the random forest algorithm and enough samples, tropical and subtropical broadleaf forest, temperate coniferous forest and nonforest partition can be extracted more accurately. Through the computation of forest cover, our result shows that China has a area of 220.42 million hectare in 2018.

Land-Use Variations in Regions with Rapid Economic Development - A Case Study in the Pearl River Delta

This study evaluates land use/cover changes (LUCC), urban expansion and landscape pattern in the Pearl River Delta (PRD) from 1995 to 2015. Specifically, analysis of spatial-temporal process and transfer directions of LUCC. From the perspective of landscape pattern analysis, select twelve types of landscape indexes, and comprehensively explore the impact of LUCC on landscape pattern. The results show that forestland has the largest area in all landscape types, occupying more than 50%. The forest coverage rate of the PRD is relatively high; meanwhile, forestland presents a spatially distributed form of aggregation. Urban-land expansion is primarily driven by population growth and economic development. The LUCC is imbalanced and shows a one-way transition; the proportion of built-up land increased from 7.91% in 1995 to 14.34% in 2015 (expansion has nearly doubled in size). The prominent built-up land expansions found in Foshan, Guangzhou, Shenzhen and Dongguan; mainly though the occupation of large amounts of forest and cropland. The landscape tends to be more fragmented and diversified. Human activities, as the main driving force, need to avoid the acceleration of the urbanization process to occupy a large amount of ecological land in future development and maintain the existing forest coverage.

Ecological pattern of urban forest landscape of Ji'nan City, China

The ecological pattern research on urban forest landscape is the foundation and premise of urban forest system planning and urban ecological construction, as well as an important way of optimizing urban spatial structure, giving full play to urban forest ecological function and creating ecological and livable environment. Ecological pattern of urban forest landscape in built-up area of Ji'nan city was quantitatively analyzed and the corresponding optimization countermeasures were put forward through quantitative analysis and gradient analysis of the overall landscape ecological pattern by RS and GIS technology with 10 landscape indices at patch level and landscape level. The results showed that urban forest coverage rate in built-up areas was 15.8%. At the landscape level, the overall landscape ecological pattern of urban forest showed following patterns: relatively complete types of urban forest landscape patches, greater degree of landscape fragmentation, different area of various types of urban forest, large major patches, and highly connected same patch types. At the level of patch type, the ecological public welfare forest was dominated by large patches. The shape of scenic recreational forest was regular and dominated by large and medium patches. The shape of road forest and subsidiary forest was complex and dominated by small patches. The production and management forest was lacking. At the level of patch type, landscape recreational forest was the dominant type, ecological public welfare forest patch area was the largest, road forest and ancillary forest fragmentation was large. At the level of landscape, urban central forest landscape fragmentation was large, human interference was serious, and landscape shape was complex. Based on the analysis of the ecological pattern of urban forest landscape, we proposed the construction scheme of Ji'nan urban forest ecological network, which was "one ring, two networks, three four axes, and multi-point chessboard". Such scheme would help strengthen the connectivity of various types of urban forests and exert overall ecological benefits of large-scale ecosystems.

EXTRACTION METHODS AND EXPERIMENT ON ESSENTIAL FOREST VARIABLES FOR GEOSPATIALLY-ENABLED SDGs MONITORING

Abstract. Since the United Nations passed the 17 Sustainable Development Goals (SDGs) and 169 sub-goals in 2015, many researchers have tried their best to put them into practise. However, mass data and different understanding of SDGs indicators make this work much more difficult. In this article we reference the concept of essential variables which may have some contribution to established a standard system for SDGs monitoring. Here we take SDG15 as an example. Firstly, we deeply analyse the main contents of SDG15 and select some geospatial-related indicators involved with forest land. From those forest-related and geospatial-enabled indicators we concise 5 essential forest variables (EFV4SDG15) which could be classified into 3 different types: land cover distribution and transformation, aggregative pattern and intensity and spatial-temporal evolution process. Secondly, formalized expression of EFV4SDG15 and extraction of them from multiple data source are necessary, including data processing and mathematical expression of the variables. Finally, we take global region as research target to carry out preliminary experiments. In this part, we only select 2 EFV4SDG15s: the forest coverage rate and forest land transfer matrix to show detailed operation process and then present the results in forms of figure and table. The paper has preliminary attempts to the application of essential variables in SDGs monitoring and provides an example for other fields.

Simulation of the Impact of Urban Forest Scale on PM2.5 and PM10 based on System Dynamics

In the context of ecological civil construction in China, afforestation is highly valued. Planting trees can improve air quality in China’s large cities. However, there is a lack of scientific analysis quantifying the impact urban forest scale has on the air quality, and what scale is advisable. The problem still exists of subjective decision-making in afforestation. Similar studies have rarely analyzed the long-term effect research of urban forests on air improvement. Using as an example, the city of Wuhan, this paper identifies the regularity between particulate matter concentration and adsorption of sample leaves, and establishes a system dynamics model of "economy, energy and atmospheric environment.” By combining this regularity with the model, the long-term impact of forest scale on particulate matter and atmospheric environment was simulated. The results show that if the forest coverage rate reaches at least 30%, the annual average concentrations of inhalable particulate matter (PM10) and fine particulate matter (PM2.5) can both reach the Grade I limit of national Ambient Air Quality Standard by 2050. The current forest cover is 22.9% of the administrative area. Increasing the forest cover by 600 km2 would increase this percentage to 30% of the total area. In the long run (by the year 2050), however, we showed that this increase would only reduce the annual concentration of PM2.5 and PM10 by 1–2%. Therefore, about 90% of the concentration reduction would still rely on the traditional emission reduction measures. More other ecological functions of forests should be considered in afforestation plan.

GIS-Based Urban Afforestation Spatial Patterns and a Strategy for PM2.5 Removal

Within the scope of ecological development planning in China, afforestation is highly valued. However, the scientific planning of afforestation still has inadequacies. There are few studies on the spatial distribution of urban forests targeted at air quality improvement. Here, we implemented a virtual experiment to evaluate whether different tree planting distribution plans with the same afforestation scale would have a significant effect on fine particulate matter (PM2.5) removal. As a case study of Wuhan, this paper identified the statistical regularity between PM2.5 concentration and adsorption of representative trees through field sampling and measurement, simulated the influence of different afforestation plans on PM2.5 concentration based on Geographic Information System (GIS), judged the significance of the difference of the plans, and proposed a greening distribution strategy. The results show that different forest layouts had no significant impact on PM2.5 in the administrative region, and the concentration reduction rate was only 1%–2%. Targeted planting of trees in heavily polluted areas in the city center would have achieved better air quality improvement, with a reduction rate of 3%–5%. In Wuhan construction areas, trees should be planted to increase the forest coverage rate to 30%. The edge of the urban metropolitan development zone needs to be strengthened with trees to form a forest belt 10 km–20 km wide, with a forest coverage rate of at least 60%. In general, the capability of trees to reduce PM2.5 concentration is weak. The fundamental way to improve air quality is to reduce emissions; planting trees is only an auxiliary measure. More ecological forest functions should be considered in city-wide afforestation distribution.

Spatiotemporal variation analysis of regional flood disaster resilience capability using an improved projection pursuit model based on the wind-driven optimization algorithm

Abstract Due to the weak methods available for evaluation of the resilience of regional flood disaster systems and the lack of research on the driving mechanism of resilience, by exploring the principles of regional flood disaster resilience and constructing a suitable evaluation index system, the wind driven optimization (WDO) algorithm was introduced, and an improved projection pursuit (PP) evaluation model of flood disaster resilience was proposed. Twelve farms under the Heilongjiang Agricultural Reclamation Hongxinglong Administration Bureau were included in the research area. A total of 43 primary indicators were selected from four criteria to describe the natural environment, culture, society, economic development and flood control technologies. The R clustering factor analysis method was used to determine 15 optimal indexes. The improved PP model based on the WDO algorithm (WDO-PP) was used to evaluate the flood disaster resilience of 12 farms. The results showed that the number of farms with a level IV rating on flood resilience decreased from 25% to 8.3% from 2002 to 2009. In 2009–2016, with the exception of the Bawuer and Shuguang farms, the flood disaster resilience index decreased, and that of the remaining farms increased. In 2002–2016, the Wujiuqi, Shuangyashan, Shuguang and Hongqiling farms in the central region of the Hongxinglong Administration Bureau were less resilient to disasters, and the farms that responded better to flood disasters were mainly located in the eastern or western Hongxinglong Administration Bureau near a river. Further analysis shows that the forest coverage rate, paddy field coverage ratio, shelter forest area ratio, proportion of primary industry, agricultural water use efficiency, and irrigation and drainage capacity were the key drivers of the flood disaster resilience in the Hongxinglong Management Bureau. Based on the Rastrigin and Schaffer functions, the results show that the success rate of the WDO algorithm is 100% over 10 iterations of the optimization calculation of the test function, while the success rate of the other two algorithms is relatively inadequate; however, in terms of value and standard deviation, both are better than adaptive particle swarm optimization (APSO) and adaptive genetic algorithm (AGA) algorithms. Moreover, in the convergence curve, the WDO algorithm converges fast, the number of iterations can achieve the optimal effect on average 3–5 times, and the AGA and APSO algorithms need more than 40 iterations to achieve the best-seeking effect. Taking the index of agricultural water use efficiency in Bawuer farm as an example, the index weight is greater than 60% and the utilization rate of agricultural water is more than 98%, which is closer to reality. Therefore, the evaluation results of the flood disaster resilience evaluation model proposed in this study are more accurate: WDO-PP>(adaptive genetic algorithm) AGA-PP>(adaptive particle swarm optimization algorithm)APSO-PP. In conclusion, the WDO-PP model has certain reference value for flood disaster recovery, monitoring and early warning.

Nonstationary Analysis for Bivariate Distribution of Flood Variables in the Ganjiang River Using Time-Varying Copula

Nonstationarity of univariate flood series has been widely studied, while nonstationarity of some multivariate flood series, such as discharge, water stage, and suspended sediment concentrations, has been studied rarely. This paper presents a procedure for using the time-varying copula model to describe the nonstationary dependence structures of two correlated flood variables from the same flood event. In this study, we focus on multivariate flood event consisting of peak discharge (Q), peak water stage (Z) and suspended sediment load (S) during the period of 1964–2013 observed at the Waizhou station in the Ganjiang River, China. The time-varying copula model is employed to analyze bivariate distributions of two flood pairs of (Z-Q) and (Z-S). The main channel elevation (MCE) and the forest coverage rate (FCR) of the basin are introduced as the candidate explanatory variables for modelling the nonstationarities of both marginal distributions and dependence structure of copula. It is found that the marginal distributions for both Z and S are nonstationary, whereas the marginal distribution for Q is stationary. In particular, the mean of Z is related to MCE, and the mean and variance of S are related to FCR. Then, time-varying Frank copula with MCE as the covariate has the best performance in fitting the dependence structures of both Z-Q and Z-S. It is indicated that the dependence relationships are strengthen over time associated with the riverbed down-cutting. Finally, the joint and conditional probabilities of both Z-Q and Z-S obtained from the best fitted bivariate copula indicate that there are obvious nonstationarity of their bivariate distributions. This work is helpful to understand how human activities affect the bivariate flood distribution, and therefore provides supporting information for hydraulic structure designs under the changing environments.