Ecological environment assessment based on land use simulation: A case study in the Heihe River Basin

Spatiotemporal Evolution and Spatial Analysis of Ecological Environmental Quality in the Longyangxia to Lijiaxia Basin in China Based on GEE

The upper reaches of the Yellow River are critical ecological barriers within the Yellow River Basin (YRB) that are crucial for source conservation. However, environmental challenges in this area, from Longyangxia to Lijiaxia, have emerged in recent years. To assess the ecological environment quality (EEQ) evolution from 1991 to 2021, we utilized remote sensing ecological indices (RSEIs) on the Google Earth Engine (GEE) platform. Spatial autocorrelation and heterogeneity impacting EEQ changes were examined. The results of this study show that the mean value of the RSEIs fluctuated over time (1991: 0.70, 1996: 0.77, 2001: 0.67, 2006: 0.71, 2011: 0.68, 2016: 0.65, and 2021: 0.66) showing an upward, downward, and then upward trend. The mean values of the overall RSEI are all at 0.65 and above. Most regions showed no significant EEQ change during 1991-2021 (68.59%, 59.23%, and 55.78%, respectively). Global Moran's I values (1991-2021) ranged from 0.627 to 0.412, indicating significant positive correlation between EEQ and spatial clustering, and the LISA clustering map (1991-2021) shows that the area near Longyangxia Reservoir shows a pattern of aggregation, dispersion, and then aggregation again. The factor detection results showed that heat was the most influential factor, and the interaction detection results showed that greenness and heat had a significant effect on regional ecosystem distribution. Our study integrates spatial autocorrelation and spatial heterogeneity and combines them with reality to provide an in-depth discussion and analysis of the Longyangxia to Lijiaxia Basin. These findings offer guidance for ecological governance, vegetation restoration, monitoring, and safeguarding the upper Yellow River's ecological integrity.

Eco-environmental changes due to human activities in the Erhai Lake Basin from 1990 to 2020

Human activities have increased with urbanisation in the Erhai Lake Basin, considerably impacting its eco-environmental quality (EEQ). This study aims to reveal the evolution and driving forces of the EEQ using water benefit-based ecological index (WBEI) in response to human activities and policy variations in the Erhai Lake Basin from 1990 to 2020. Results show that (1) the EEQ exhibited a pattern of initial degradation, subsequent improvement, further degradation and a rebound from 1990 to 2020, and the areas with poor and fair EEQ levels mainly concentrated around the Erhai Lake Basin with a high level of urbanisation and relatively flat terrain; (2) the EEQ levels were not optimistic in 1990, 1995 and 2015, and areas with poor and fair EEQ levels accounted for 43.41%, 47.01% and 40.05% of the total area, respectively; and (3) an overall improvement in the EEQ was observed in 1995-2000, 2000-2005, 2005-2009 and 2015-2020, and the improvement was most significant in 1995-2000, covering an area of 823.95 km2 and accounting for 31.79% of the total area. Results also confirmed that the EEQ changes in the Erhai Lake Basin were primarily influenced by human activities and policy variations. Moreover, these results can provide a scientific basis for the formulation and planning of sustainable development policy in the Erhai Lake Basin.

Space-time cube uncovers spatiotemporal patterns of basin ecological quality and their relationship with water eutrophication

Maintaining an optimal eco-environment is important for sustainable regional development. However, existing methods are inadequate for examining both spatial and temporal dimensions. Here, we propose a systematic procedure for spatiotemporal examination of the eco-environment using the space-time cube (STC) model and describe a preliminary investigation of the coupling relationships between basin ecological quality and water eutrophication in upstream of the Han River basin between 2000 and 2020. The STC model considers the temporal dimension as the third dimension in calculations. We first categorized the basin into three sub-watershed types: forest, cultivated land, and artificial surface. Subsequently, the ecological quality and driving factors were assessed and identified using the remote sensing ecological index (RSEI) and Geodetector method, respectively. The findings indicated that the forest basin and artificial surface basin had the highest and lowest ecological quality, respectively. The spatiotemporal cold spots of ecological quality during the past 20 years were mostly located in the vicinity of reservoirs, rivers, and artificial surface areas. Human activity, precipitation, and the percentage of cultivated land were other important driving factors in the artificial surface, forest, and cultivated land sub-watersheds, respectively, in addition to the dominant factors of elevation and temperature. The results also indicated that when the ecological quality degraded to a certain extent, water eutrophication was significantly coupled with the ecological quality of the catchments. The findings of this study are useful for ecological restoration and sustainable river basin development.

Contributions of climate change and urbanization to urban flood hazard changes in China's 293 major cities since 1980

The growing incidence of urban flood disasters poses a major challenge to urban sustainability in China. Previous studies have reported that climate change and urbanization exacerbate urban flood risk in some major cities of China. However, few assessments have quantified the contributions of these two factors to urban flood changes in recent decades at the nationwide scale. Here, surface runoff caused by precipitation extremes was used as the urban flood hazard to evaluate the impacts of climate change and urbanization in China's 293 major cities. This study assessed the contributions of these drivers to urban flood hazard changes and identified the hotspot cities with increased trends under both factors during the past four decades (1980-2019). The results showed that approximately 70% of the cities analyzed have seen an increase of urban flood hazard in the latest decade. Urbanization made a positive contribution to increased urban flood hazards in more than 90% of the cities. The contribution direction of climate change showed significant variations across China. Overall, the absolute contribution rate of climate change far outweighed that of urbanization. In half of the cities (mainly distributed in eastern China), both climate change and urbanization led to increased urban flood hazard over the past decade. Among them, 33 cities have suffered a consecutive increase in urban flood hazard driven by both factors.

Spatio-temporal evolutionary analysis of surface ecological quality in Pingshuo open-cast mine area, China

The open-pit mining area is highly affected by human activities, which aggravate soil erosion and disturb surface ecology, bringing many problems and challenges to its environmental management and restoration, which has received widespread attention. The establishment of an objective, timely and quantitative remote sensing monitoring, and evaluation system for the spatio-temporal evolution of the surface ecological environment in the open-pit mining area is of great significance for its environmental protection, management decisions, and sustainable social development. Based on the Google Earth Engine (GEE) platform, this paper uses Landsat images to construct and calculate the remote sensing ecological index (RSEI) of the Pingshuo open-cast mine area (POMA) from 1990 to 2020 and monitor and evaluate its surface ecological environment. Combined with the Theil-Sen median, Mann-Kendall test, and Hurst index, the spatio-temporal process was analyzed. The results showed that the ecological environmental quality of the mining area first decreased and then increased from 1990 to 2020. 1990-2000 was a period of serious ecological degradation, followed by improvement. The overall improvement area reached 87.03%, and the degradation was concentrated in the coal mining area. Between 1990 and 2020, the Hurst index of the mining area was 0.452, indicating that the region has a fragile ecological environment and has difficult maintaining its stability. The global Moran's I mean value of the RSEI of the study area is 0.92, which combined with Moran's scatter plot to indicate that there is a strong positive spatial correlation rather than a random distribution of its ecological environment. During the study period, the impact on the climate of the ecological environmental change of POMA was weak, and human factors such as coal mining, land reclamation, and social construction were the main driving forces for the change in ecological quality. The results of this study reveal the changing trend of surface ecology in the mining area over the past 30 years, which is helpful for understanding its impact mechanism on ecological quality and provides support for the management of the region.

Lake shrinkage-induced terrestrial ecological environmental quality degradation in a semiarid lake basin

Lake water environmental problems caused by lake shrinkage in semiarid zones have attracted widespread attention, but few studies have quantified the impact of lake shrinkage on the terrestrial ecological environmental quality of watersheds. In this study, remote sensing image inversion, digital elevation modeling, and statistical analysis were applied to explore the impact of Lake Daihai shrinkage on the terrestrial ecological environmental quality of its receding water areas from 1986 to 2019. The results showed that the area of Lake Daihai shrank from 170.7 km2 in 1961 to 50.67 km2 in 2019, a shrinkage of 70.32%. The average annual shrinkage was 2.07 km2 during the period of 1986-2019 (r = -0.99, p < 0.01). The main conclusions of this study are as follows: The mean remote sensing ecological index values decreased significantly from 0.628 in 1986 to 0.441 in 2019 (r = -0.78, p < 0.05), which means that the terrestrial ecological environmental quality of the water receding area degraded from a good grade to a moderate grade. The increase in water use by residents in the basin was an important reason for the shrinkage of Lake Dahai. Approximately 90% of the wetlands in the receding water areas formed after the shrinkage of Lake Daihai were converted to farmland by local residents, which significantly degraded the terrestrial ecological environmental quality of these areas from good to moderate grade over the 34-year period (r = -0.83, p < 0.05). Correlation analysis indicated that the remote sensing ecological index was positively correlated with lake area (r = 0.85, p < 0.01). The results indicate that steps should be taken to decrease the impact of human activities on the terrestrial ecological environmental quality of lake basins in semiarid zones.

Spatial-temporal evolution and driving force analysis of eco-quality in urban agglomerations in China

Urban agglomerations are important spatial carriers of regional economic development, and their ecological quality (EQ) is closely related to economic growth and human development. However, the rapid urbanization in China has generated a series of EQ problems that threaten the sustainable development of the country. Therefore, it is essential to explore changes in EQ for the development of sustainable "human-land" relations in urban agglomerations. Using GIS, GeoDetector, Stepwise multiple regression, and Sen'trend analysis, to reveal the spatial-temporal evolution of EQ in urban agglomerations along with the spatial heterogeneity of its driving forces in China. Results show that: (1) The annual change rate of EQ of urban agglomerations ranges from -0.0312 to 0.0334. Taking the Hu-line as a boundary, the EQ of urban agglomerations is spatially high in the east and low in the west. (2) The Global Moran's I index ranged from 0.740 to 0.687 during the study period, indicating a positive correlation in the EQ spatial distribution. The EQ of urban agglomerations has significant spatial agglomeration, with hot spots concentrated in the eastern region and cold spots in the northwestern region. (3) Main drivers of EQ of urban agglomerations are elevation, population density, nighttime light index, arable land area, real GDP per capita, precipitation, and built-up urban area (q > 10 %). (4) The stepwise multiple regression model spatially reveals that the nighttime light index, built-up urban area land and GDP per capita dominate the ecological quality changes of urban agglomerations, accounting for 73.68 % of the total number of urban agglomerations. This study provides an effective method for assessing spatial-temporal changes of EQ in urban agglomerations, supports scientific decision-making support for the construction of ecological civilization and the development of human-land harmony in urban agglomerations, and promotes the development and construction of "Beautiful China."

A methodological framework for assessing pastoral socio-ecological system vulnerability: A case study of Altay Prefecture in Central Asia

Vulnerability analysis is important for enhancing sustainability, especially for highly interlinked pastoral socio-ecological systems. This study presents a modified methodological framework for assessing the vulnerability of pastoral socio-ecological systems based on the interactions between social and ecological subsystems and their vulnerabilities. Altay Prefecture (Northwest China), a typical pastoral area located in Central Asia, was chosen for the case study. The ecological vulnerability index (EVI) and socio-ecological vulnerability index (SEVI) of Altay Prefecture from 2001 to 2018 were assessed and classified into five levels. The results showed that the distribution pattern of EVI was spatially heterogeneous, with EVI increasing from north to south and from west to east. The EVI was high in low-altitude deserts, decreased with altitude rising from 1300 m to 2200 m, and increased when the altitude exceeded 2200 m. The average EVI increased from 2001 to 2010 and decreased from 2010 to 2018, with the highest EVI in 2010 and the lowest in 2018. The SEVI of western counties was lower than that of eastern counties; the SEVI of all counties continuously decreased from 2001 to 2018, with a higher rate from 2010 to 2018. Social adaptive capacity, increased by the policies that aim at protecting grasslands and improving livelihoods, was the main influencing factor of the SEVI dynamic. These results will help to identify key areas with high EVI for grassland ecosystem management and strengthen the adaptive capacity for addressing vulnerability. Furthermore, the presented methodological framework can be adopted in vulnerability assessments of similar pastoral areas or natural resource-based socio-ecological systems.

Does location of the households' matters? Identifying the households' willingness to pay and preference heterogeneity in advancement of vulnerable ecosystem services: An approach of choice experiment

The present research underlines the need to expand far outside bundling or hierarchical providing strategy that often focuses on a specific habitat or ecosystem and creates a location-based strategy that considers how dependency in other parts of the region with ecosystem functions and processes leads to complements and resources' trade-offs. Thus, for assessment of spatial heterogeneity based on willingness to pay (WTP) for upgrading environmental attributes across Heihe River Basin (HRB), a choice experiment survey was carried out in the entire river basin. The HRB is one of the big inland river in the Northwestern region of China and is selected on basis of its geomorphological and geographical significance. A sum of 1679 individuals were interviewed through choice experiment technique from whole river basin consisting of five main cities and 33 adjoining rural areas. The Random Parameter logit model, Krinsky-Robb technique as well as delta method were applied for the evaluation of spatial heterogeneity and estimation of individual specific WTP, respectively. Spatial heterogeneity is verified among sampled individuals' preferences about upgradation of environmental attributes, such as, observed preferences of individuals' and their varying corresponding WTP amounts for per unit's upgradation in agriculture product quality, greenhouse gases reduction, farmland landscape, and biodiversity, which reflects heterogeneous tastes and preferences of the selected individuals. In addition, the assessed outcomes for identifying the impacts of distance decay through random parameter logit model depicted the vital role of distance influence on respondents' WTP for restoring the degraded environmental attributes, such that among 3 ad hoc distance bands, WTP of those sampled individuals who are in proximity of ≤ 10 km to HRB is more than the rest of the individuals, i.e., individuals living in the range of ≤ 20 km and > 20 km. For instance, WTP for agriculture product quality is 119.147 CNY/year in ≤ 10 km and is higher than the remainders.

Spatial and temporal variation of multiple eco-environmental indicators in Erhai Lake Basin of China under land use transitions

Environmental degradation is a global ecological concern, and land use transitions play a critical role in a region's ecological well-being and long-term sustainability. In this paper, indicators related to land use transitions, including the regional eco-environmental quality index (EV), the remote sensing ecological index (RSEI), and soil erosion, are selected to analyze the eco-environmental quality of Erhai Lake Basin from 2000 to 2020. The results showed that (1) from 2000 to 2020, forestland, grassland, and cultivated land were the major land use types in the study region, and also the land use types where land use transition was notable; (2) over the 20 years of study, the EV value of Erhai Lake Basin increased by 0.003, its average RSEI increased by 0.14, and the average soil erosion modulus there decreased by 15.48 t/(km²·a), indicating that the eco-environment of the Erhai Lake Basin was improving. Evaluation based on multiple ecological indicators was superior to assessment relying on single indicators; (3) all three ecological indicators showed that the ecological environment of the basin was improving, but with significant regional differences. Forestland had the best ecological quality, while unused land and built-up land had the worst. RSEI was more regionally adaptable than the other two indices. (4) The transition of cultivated land into other land use types was the main reason for the improved ecological quality in the basin, while tourism had accelerated land use transformation. Compared with assessment based on single ecological indicators, evaluation based on a combination of multiple ecological indicators can more accurately reflect the ecological condition of the study area and provide a basis for eco-environmental protection in Erhai Lake Basin.

Trade-offs and synergistic relationships of ecosystem services under land use change in Xinjiang from 1990 to 2020: A Bayesian network analysis

Ecosystem service value (ESV) refers to the value of benefits provided by the ecosystem to people, and can reflect the quality of regional ecological environment. There have been few studies on ESV in arid regions experiencing dramatic land use changes. Also, many past ESV studies have obtained distorted results by using a simple linear function to examine the trade-offs between driving factors. This study quantified ESV in Xinjiang from 1990 to 2020 based on value equivalent method. Differences in ESV among ecosystem services in Xinjiang under different scenarios were simulated using a Bayesian network model. The results demonstrated land use changes in Xinjiang from 1990 to 2020, with construction land expanding the most significantly (dynamic index: 224.63 %), whereas grassland area decreased (dynamic index: -1.31 %) due to transformation to unused and cultivated land. ESV in Xinjiang presented an N-shaped variation trend from 1990 to 2020 and decreased by 309.6 × 10⁸ CNY, with a variation rate of -20.35 %. The rank of the four categories of ecological services from 1990 to 2020 in terms of ESV was: regulating services > support services > cultural services > supply services. There was a gradual reduction in ESV in Xinjiang from 1990 to 2020. The rank of the different regions in terms of the reduction in ESV was: Northern Xinjiang (295.24 × 10⁸ CNY) > Southern Xinjiang (280.94 × 10⁸ CNY) > Eastern Xinjiang (109.76 × 10⁸ CNY). Land use change was a direct driver of changes in ESV, whereas natural and social factors, such as precipitation, temperature, population, and policy factors, were indirect drivers. This study can act as a reference for sustainable management of ecosystem services in arid regions.

The local coupling and telecoupling of urbanization and ecological environment quality based on multisource remote sensing data

Coordinating the relationship between urbanization and ecological environment quality (EEQ) is crucial to achieving sustainable development. With the development of globalization, the pattern of remote interaction between urbanization and EEQ has gradually increased. However, the current study on the coupling of urbanization and EEQ lacks a remote perspective, and the remote sensing ecological index (RSEI) model has not yet considered the environmental pollution caused by population agglomeration. For these reasons, this study proposes the remote sensing ecological environment index (RSEEI) model and measures the local coupling and telecoupling coordination degree (LTCCD) of urbanization and EEQ in China from 2000 to 2020. According to the results, the rate of change of EEQ in China was -0.00011a^-1. RSEEI widens the gap between the east and west of EEQ, differentiated by the Heihe-Tengchong Line. China's urbanization is growing at a 0.0008a^-1 rate, with a spatially driven radiation potential with Beijing, Shanghai, Hong Kong, and Macao as the core. LTCCD follows an increasing trend from inland to coastal and west to east. Over 70% of provinces experienced a shift in adjacent LTCCD levels, and 14 provinces moved from disorder to coordination after 2010. The telecoupling strengthens the correlation between urbanization and EEQ among regions compared with traditional coupling. In addition, the eastern coastal areas, the northern and central-south inland areas, and the northwest face different coordination problems.

Circuit theory-based ecological security pattern could promote ecological protection in the Heihe River Basin of China

Building ecological security patterns is essential to maintain regional ecological security and achieve sustainable development in the inland river basins with ecologically vulnerable environment. Numerous methods have been developed to build the ecological security pattern. However, to our knowledge, rare studies have quantified to what extent the derived pattern can improve ecological protection in the future. Taking Heihe River Basin (HRB), the second largest inland river basin in China, as the study area, we applied the circuit theory to build the ecological security pattern of HRB, and simulated how our built pattern contributed to ecological protection using the CLUMondo model. The results showed that the ecological security pattern of HRB contained 17 ecological sources, 35 key ecological corridors, and some ecological strategic points. The ecological sources were distributed in areas with better ecological conditions such as the Qilian Mountain Nature Reserve and Heihe National Wetland Park. The ecological corridors showed a pattern of "two horizontal and three vertical belts." Pinch points were mostly close to ecological sources or distributed on the corridors that played a key role in landscape connectivity, while barriers were mainly distributed on the corridors with large ecological resistance in the middle and lower reaches. The optimal ecological security pattern presented a "one screen, one belt, four districts and multiple centers" shape in HRB and could more effectively promote ecological protection compared to current development and protection scenarios. Our study provides a reliable decision-making guide for ecological protection and restoration of HRB, and can be extended to build ecological security patterns for broad-scale arid areas.

Quantifying the spatial preferences heterogeneity to upgrade the endemic ecological attributes for a cleaner environment: Evaluating the feasibility of benefit transfer among sub-basins of an inland river

The role of wetlands in the conservation of global biodiversity is very significant due to the provision of various benefits to households. The assessment of these benefits and general public perception in terms of their willingness to pay for restoring the degraded ecosystem services is also heterogeneous because of their spatial preferences. This research employed a choice experiment technique to evaluate willingness to pay of the households to improve the current degraded ecosystem services and assessed benefit transfer among upper, middle and lower sub-basins of Heihe River. The outcomes of the study were estimated through two models, i.e. the conditional logit and random parameter logit models. The heterogeneous willingness to pay amounts for ecosystem services confirm the variations in taste and preferences of the respondents across all sub-basins. Considering spatial heterogeneity of the preferences, the random parameter logit model resulted in smaller transfer errors than the conditional logit model. The values of transfer errors estimated by the random parameter logit model from the lower to the upper sub-basin, from the upper to the middle sub-basin and from the middle to the lower sub-basin were 17.76%, 80.65% and 33.92%, respectively, and the reason for these smaller values is the consideration of taste and preferences of the respondents. On the other hand, the estimated values of transfer errors for the same settings in the conditional logit model were 21.93%, 109.31% and 43.08%, respectively. The transfer error values thus validate the transfer of benefits across all the sub-basins of the river. Therefore, the current findings are helpful in proper management of ecosystem services and permit for benefit transfer from one sub-basin to another sub-basin of Heihe River.

A novel multi-model fusion framework diagnoses the complex variation characteristics of ecological indicators and quantitatively reveals their driving mechanism

Systematic analysis of the change law and driving mechanism of ecological indicators (GPP, ET, WUE), as well as the study of maximum threshold of water resources benefit changing with ecological benefit, are important prerequisites for realizing the scientific allocation and efficient utilization of water resources in desert riparian forests. However, previous studies have defects in the detailed description of the change characteristics of ecological indicators. How to accurately diagnose the characteristics of a site, mutation year, pattern (linear, exponential, logarithmic, etc.), duration of change, future change trends of ecological indicators in a desert riparian environment, as well as quantitatively revealing their driving mechanisms, are major scientific problems that need to be solved urgently. In this regard, an ensemble function coupling a logistic function and an asymmetric Gaussian function was creatively adopted, a novel framework was created to integrate the time-series trajectory fitting method and the sensitivity analysis method, and the arid and ecologically fragile Tarim River Basin was taken as a typical area. The results showed that with enhanced water resource management in the Tarim River Basin, GPP, ET, and WUE all showed patterns of increasing change and could be expected to continue to rise or to remain at a high-level stable state. The longest continuous period of GPP change was 15 years, showing that ecological restoration is a long-term process. The years of GPP mutation were consistent with the implementation periods of major measures in the Tarim River Basin (1990, 2001, and 2011), indicating the reliability of this framework. More importantly, when GPP increased to 216.44 gCm^-2, the maximum WUE threshold of 0.93 gCm^-2mm^-1 occurred. This threshold can be used as a reference criterion for efficient utilization of ecological water in the basin. Among the ecological indicators studied, GPP was the most sensitive to environmental change, but GPP, with 80.60% of pixel area, showed a weak memory effect（α < 0.4). Besides, GPP was the most sensitive to the leaf area index (LAI) and had the strongest correlation with it (p < 0.001). Therefore, LAI can be used as the main control factor for judging plant growth. This research can provide important scientific guidance and reference for the analysis of ecological indicator changes and the sustainable utilization of water resources in arid areas.

Neighboring Effects on Ecological Functions: A New Approach and Application in Urbanizing China

Rapid urbanization has widely induced fragmented landscapes and further negatively affected ecological functions. The edge effect is an approach commonly used to investigate these negative impacts. However, edge effect research tends to focus on the impacts that a certain landscape receives from its adjacent lands rather than to assess all the influences of the landscape edges in a region, even though the latter is critical for regional ecological planning. To fill in this gap, the concept of neighboring effect is raised and analyzed in this paper with a case study of Xintai City in Northern China. Results show that the neighboring effects are generally negative for ecological functions, especially in regions that experience rapid urbanization or heavy human activities. The U-shaped relationship between the neighboring effect of a patch and its distance to the nearest township center indicates that the border region of urban and built-up areas suffers the most negative influences due to the intense interactions between different land uses. The heterogeneous effects of influencing factors in urban and rural areas were revealed by the regression results. Socioeconomic development has more important influence on neighboring effects on ecological functions in rural areas than in urban areas, and local cadres’ support of environmental protection matters only in rural areas for a less ecological functional loss. This study quantitatively examined the negative ecological effects of landscape fragmentation during rapid urbanization and calls for more attention to ecological planning at the local scale.

Monitoring and Evaluation of Eco-Environment Quality Based on Remote Sensing-Based Ecological Index (RSEI) in Taihu Lake Basin, China

Rapid and effective access to the spatiotemporal patterns and evolutionary trends of the regional eco-environment is key to regional environment protection and planning. Based on the Google Earth Engine platform, we use 165 Landsat images from the summer and autumn seasons (May–November) of 2000, 2010, and 2018 as data sources to calculate the RSEI, which represents the quality of the eco-environment, and then analyze the factors influencing the spatial heterogeneity of the eco-environment and the relationship between eco-environment and land-use changes based on RSEI. The results showed the following: (1) From 2000 to 2018, the overall ecological environment quality of the Taihu Lake Basin showed a stage of rapid decline (2000–2010) and a stage of slow decline (2010–2018). (2) The factors were ranked in order of their explanatory power for the spatial heterogeneity of the RSEI: land-use (0.594) > population density (0.418) > slope (0.309) > elevation (0.308) > GDP (0.304) > temperature (0.233) > precipitation (0.208). An interactive effect was found for each factor of the RSEI, which is mainly represented by a mutual enhancement. (3) From 2000 to 2010, the rapid urban expansion was the main reason for the deterioration of ecological quality. From 2010 to 2018, urban expansion slowed down, and the trend of ecological quality deterioration was effectively curbed. Therefore, promoting the intensive use of land and reducing construction land expansion are key to ensuring sustainable regional socio-economic development.

Ecological Impacts of Land Use Change in the Arid Tarim River Basin of China

Land use/cover change has become an indispensable part of global eco-environmental change research. The Tarim River Basin is the largest inland river basin in China. It is also one of the most ecologically fragile areas in the country, with greening and desertification processes coexisting. This paper analyzes the evolution of land-use/cover change in the Tarim River Basin over the past 30 years based on remote sensing data. The research also explores the contribution of conversion between different land types to the ecological environment by selecting methods, such as transfer matrix and ecological contribution rate. Results indicate that grassland and barren land are the main land types in the region, accounting for 72.46% and 18.87% of the basin area, respectively. From 1990 to 2019, cropland area increased from 33,585.89 km2 to 52,436.40 km2, an increase of 56.13%, while barren land areas decreased from 781,380.57 km2 to 760,783.29 km2. Most of the land-use conversion was grassland to other land types and other land types to barren land. Since 1990, the conversion of barren land to grassland and cropland in the basin has led to ecological improvement, whereas the conversion of grassland to cropland has caused deterioration, but with a generally improving trend. It is anticipated that, over the next decade, changes in land types will involve increases in grassland and woodland area, decreases in barren land and cropland, and an overall improvement in the ecological environment in the watershed. Since agriculture and animal husbandry are the main industries in the Tarim River Basin and the land-use structure is dominated by cropland and grassland, several key measures should be implemented. These include improving land use, rationalizing the use of water and soil resources, slowing down the expansion of cropland, and alleviating the contradiction between humans and land, with the ultimate aim of achieving sustainable development of the social economy and ecological environment.

Information entropy and elasticity analysis of the land use structure change influencing eco-environmental quality in Qinghai-Tibet Plateau from 1990 to 2015

Regional land use change affects eco-environmental quality by altering ecosystem structure and function. The primitive ecosystem and environment of the Qinghai-Tibet Plateau (QTP) occupies a special position in the world, but it is very fragile. Although land use activities on the plateau have increased gradually in past decades, its effects on eco-environmental quality and the underlying mechanisms of regional heterogeneity remain unclear. In this study, an eco-environmental quality assessment index system was established to characterize the QTP, and the information entropy and elasticity methods were introduced to quantify the impact of land use dynamic trajectory on the eco-environmental quality. It provides a statistical measurement of system structure and more information than the traditional methods to reveal the land use change. The area change in land use on QTP was small from 1990 to 2015. The unused land and forest decreased, but those of grassland, water body, built-up land, and cultivated land increased. The overall eco-environmental quality on the QTP was low, and increased at a rate of 9.39% over the past 25 years, presenting a distribution of decreasing from southeast to northwest. The improvement in eco-environmental quality attributed to land use change was mainly due to the conversion of unused land into grassland, and ecological conservation projects also improved the local ecological environment. Conversely, the expansion of built-up land and land degradation contributed to decline in local eco-environmental quality in the Hengduan Mountains, northeastern plateau, and Qaidam Basin. The results indicated that under the influence of climate change, the changes in land use and eco-environmental quality were inconsistent in part regions, mainly including the central and southern Tibet and the border zone. Regions in which eco-environmental quality has been degraded by unreasonable land use are urgent to optimize land use management.

Construction of a theoretical model for fan nozzles with precise atomization angles for plant protection

The fan nozzle is widely used in the process of pest control in agriculture and forestry. The spray angle of the nozzle is an important characterization parameter in the atomization of liquids. The spray angle of the nozzle is an important characterizing parameter in the liquid atomization process. It affects the flow field at the exit of the nozzle, thereby affecting the size and velocity of the droplets, and further affecting the deposition effect of the droplets on the crop. Therefore, its research is of great significance for improving the deposition of liquid on plants and controlling pests and related diseases. Based on the classical theory of predecessors and considering the parameters of the flat fan nozzle, we further optimized the theory at the structural level by means of a simulation test and built a spray angle theoretical model taking into account the parameters of the inner chamber of the nozzle. We arrived at the following conclusions: (1) the average error of the spray angle measured by the simulation test and the actual test spray angle was 2.95%, the maximum spray angle deviation value was 2.81°, and the result proves that the simulation test parameter setting is accurate; and (2) the average error between the actual measured value and the theoretical model calculation value was 3.56%, the maximum spray angle deviation was 4°, through the actual test comparison, and the spray angle error of the theoretical model was within the allowable error range of industry production. It was proved that the model could effectively reflect the changing law of spray angle of the flat fan nozzle.

Vulnerability assessment and management planning for the ecological environment in urban wetlands

As a special ecosystem in cities, urban wetland parks have important environmental regulation and social service functions. This paper proposes a new methodology of urban wetland planning and management based on the vulnerability of the ecological environment. The Jixi National Wetland Park (JNWP) was taken as the research area to analyze the ecological, geological and environmental factors that affect urban wetlands. A remote sensing image, digital elevation model, and environmental quality interpolation processing were used to generate the factor layer, and a comprehensive evaluation index system was established. The fuzzy Delphi analytic hierarchy process (FDAHP) method was used to calculate the comprehensive weight of each evaluation factor. A model to evaluate the ecological environment vulnerability of the JNWP was established. Then, an improved k-means clustering algorithm was used to classify the ecological environment of the study area. The ecological environment vulnerability of the wetland was evaluated. The results showed that the vulnerability of the ecological environment in the study area could be divided into five levels, including very low, low, medium, high and very high vulnerability areas. According to the vulnerability level and the results of k-means++ cluster analysis, the JNWP is divided into five areas. The wetland buffer zone is the main factor that determines the distribution of ecological environment vulnerability in urban wetlands. However, cultivated land development and ecological environmental restoration are the main factors that determine the evolution of ecological environment vulnerability in urban wetlands. The FDAHP and geographic information systems (GIS), combined with cluster analysis, are effective methods to evaluate the vulnerability of the ecological environment of urban wetlands, which provides a scientific and accurate methodology for the management and sustainable development of urban wetlands.

Scenario-Based Analysis of Land Use Competition and Sustainable Land Development in Zhangye of the Heihe River Basin, China

Rapid economic growth has a significant impact on land use change, which would threaten the natural ecology. Zhangye city of the Heihe River Basin, China is an ecologically vulnerable region where land use changes significantly due to socioeconomic development and population increases. The study employed a computable general equilibrium of land use change (CGELUC) model to simulate land use change and then used a dynamic land system (DLS) model to spatialize land use change during 2015-2030 under three development scenarios in Zhangye city. The three development scenarios are the baseline scenario (BAU), the resource consumption scenario (RCS) and the green development scenario (GDS). We found that economic growth would lead to land demand increases in high value-added industries and decreases in low value-added industries. The cultivated land would decrease while the built-up area would increase. By 2030, the cultivated land will decrease by 8.16%, 10.89% and 4.16%, respectively, under BAU, RCS and GDS, while the built-up area will increase by 8.61%, 10.39% and 4.75%, respectively. The expansion of built-up area under RCS presents spatial characteristics of centralized distribution, while spatial characteristics of uniform discrete distributions are presented under GDS. The expansion of ecological land under GDS would be considerable, especially in the north of Sunan County and Gaotai County, and around the natural reserve of Ganzhou County. This paper provides a scientific reference for coordinating economic development and ecological protection in the rapidly developing urbanized areas in western China.

Simulation and optimization of land use pattern to embed ecological suitability in an oasis region: A case study of Ganzhou district, Gansu province, China

High-intensity land use has led to water resource imbalance and land degradation in oasis regions, which pose a great threat to ecological security. Optimization of land use patterns is crucial to ensuring the rational distribution of water and land resources and improving the stability of oasis ecosystems. The purpose of this study is to spatially allocate land use activities to more suitable regions. In this study, we first evaluated the land ecological suitability (LES) in Ganzhou District, a typical oasis region. Then, the LES evaluation results were embedded in an integrated CA-Markov model based on multiple criteria evaluation (MCE) and multi-objective land allocation (MOLA) to simulate and optimize land use patterns for the year 2025 under two scenarios, i.e., Business as Usual (BAU) and Land Ecological Optimization (LEO). The results revealed that the optimized land use pattern generated by LES was more reasonable. The growth rate of construction land was restricted, and a slightly increased area of construction land mainly occupied unused land. Farmland area had a decreasing trend, and was mainly converted to grassland. Moreover, the woodland and water areas had increasing trends. This study can serve as a scientific reference for planners and policy makers in formulating land use planning and land use resource management strategies in oasis regions.

Evaluation of Ecological Environment Effect of Villages Land Use and Cover Change: A Case Study of Some Villages in Yudian Town, Guangshui City, Hubei Province

Rapid economic development has a significant negative impact on the rural ecological environment. Evaluating the ecological environmental effect of land use and its change trend at the village scale has important practical significance for maintaining ecological functions and ensuring ecological safety. Taking a typical village in Yudian Town as an example, we applied a land-use ecological environment effect evaluation and the CA-Markov change trend prediction model and constructed an index of ecological environmental effect status. Based on the land use, resource environment, and social economic data from 2014 and 2019, we evaluated the ecological environmental effects of land use in each village, simulated the land-use change in each village in two different scenarios, i.e., the developmental orientation (DO) and ecological orientation (EO), in 2030, and analyzed the corresponding change trend of the land-use effect. The ecological environmental effect of land use showed obvious characteristic differentiation in villages with different development levels. For example, villages with poor natural geographic background conditions and slower economic development had a good level of ecological environmental effect, whereas villages with better resource and environmental endowments but faster economic development had lower levels of ecological environmental effect. Village land-use management methods have had a certain effect on improving ecological security, but the effect has been slow. In conclusion, the research results portray the relationship between rural land use and ecological environmental effects in low hilly areas in northern Hubei at a small scale and have reference value for land resource allocation and spatial pattern optimization in similar regions.

Hybrid model for ecological vulnerability assessment in Benin

Identifying ecologically fragile areas by assessing ecosystem vulnerability is an essential task in environmental conservation and management. Benin is considered a vulnerable area, and its coastal zone, which is subject to erosion and flooding effects, is particularly vulnerable. This study assessed terrestrial ecosystems in Benin by establishing a hybrid ecological vulnerability index (EVI) for 2016 that combined a composite model based on principal component analysis (PCA) with an additive model based on exposure, sensitivity and adaptation. Using inverse distance weighted (IDW) interpolation, point data were spatially distributed by their geographic significance. The results revealed that the composite system identified more stable and vulnerable areas than the additive system; the two systems identified 48,600 km² and 36,450 km² of stable areas, respectively, for a difference of 12,150 km², and 3,729 km² and 3,007 km² of vulnerable areas, for a difference of 722 km². Using Moran's I and automatic linear modeling, we improved the accuracy of the established systems. In the composite system, increases of 11,669 km² in the potentially vulnerable area and 1,083 km² in the highly vulnerable area were noted in addition to a decrease of 4331 km² in the potential area; while in the additive system, an increase of 3,970 km² in the highly vulnerable area was observed. Finally, southern Benin was identified as vulnerable in the composite system, and both northern and southern Benin were identified as vulnerable in the additive system. However, regardless of the system, Littoral Province in southern Benin, was consistently identified as vulnerable, while Donga Province was stable.

Assessment of Land Ecological Security and Analysis of Influencing Factors in Chaohu Lake Basin, China from 1998–2018

The land ecosystem provides essential natural resources for the survival and development of human beings. Therefore, land ecological security (LES) acts as a vital part of the sustainable development of human society and economy. This study included a dynamic analysis of land use change in Chaohu Lake Basin (CLB) in China from 1998 to 2018, evaluating the spatiotemporal patterns of LES at both the administrative district scale and grid scale (200 m × 200 m). Then, geographic detector was applied to analyze the influence of the assessment index on LES. The results show that in the 2008–2018 period, land use changed more significantly compared to the 1998–2008 period. The continuous extension of urban land led to a decrease in the areas of other land use types. In the CLB (administrative district scale), the LES levels varied throughout the study period. In Changfeng, Feixi, and the other three regions, the LES has been significantly improved. However, the LES in six other regions showed different degrees of decline, particularly in Hexian and Urban Hefei. Simultaneously, the LES showed a gradual improvement at a 200 m × 200 m grid scale level. The influence of anthropogenic factors on the LES was stronger than natural factors. Findings from this study provide reliable guidance for improving the ecosystem environment in ecologically fragile areas.

Impacts of Climate Change and Human Activity on the Runoff Changes in the Guishui River Basin

Guishui River Basin in northwestern Beijing has ecological significance and will be one of the venues of the upcoming Beijing Winter Olympic Games in 2022. However, accelerating climate change and human disturbance in recent decades has posed an increasing challenge to the sustainable use of water in the basin. This study simulated the runoff of the Guishui River Basin using the Soil and Water Assessment Tool (SWAT) model to reveal the spatio-temporal variations of runoff in the basin and the impacts of climate change and human activities on the runoff changes. The results showed that annual runoff from 2004 to 2018 was relatively small, with an uneven intra-annual runoff distribution. The seasonal trends in runoff showed a decreasing trend in spring and winter while an increasing trend in summer and autumn. There was a first increasing and then decreasing trend of average annual runoff depth from northwest to southeast in the study area. In addition, the contributions of climate change and human activities to changes in runoff of the Guishui River Basin were 60% and 40%, respectively, but with opposite effects. The results can contribute to the rational utilization of water resources in the Guishui River Basin.

The valuation of China's environmental degradation from 2004 to 2017

This paper aims to evaluate the cost of environmental degradation by adopting the conventional environmental economic methodology in China from 2004 to 2017 and summarize the change in both the causes and costs of China's environmental degradation. Results from this study revealed the following: i. The environmental degradation cost in China increased from 511 billion yuan to 1,892 billion yuan from 2004 to 2017, and its share in the GDP decreased from 3.05% to 2.23%; ii. The environmental degradation cost growth rate was lower than the GDP growth rate. The environmental degradation cost growth rate decreased sharply, by dropping from 10% in 2014 to 2% in 2017. The environmental benefits of industrial transformation have emerged; iii. The provinces of Shandong, Hebei, Jiangsu, Henan, and Guangdong had the highest environmental degradation costs. The annual average growth rate of the environmental degradation costs in Jiangsu, Guangdong, and Zhejiang were lower than their growth rate of the GDP respectively; iv. Consideration of environmental degradation cost in decision-making could contribute to the high-quality development of China.

Impacts of Land Use and Land Cover on Water Quality at Multiple Buffer-Zone Scales in a Lakeside City

Understanding the effect of land use/land cover (LULC) on water quality is essential for environmental improvement, especially in urban areas. This study examined the relationship between LULC at buffer-zone scales and water quality in a lakeside city near Poyang Lake, which is the largest freshwater lake in China. Representative indicators were selected by factor analysis to characterize the water quality in the study area, and then the association between LULC and water quality over space and time was quantified by redundancy analysis. The results indicated that the influence of LULC on water quality is scale-dependent. In general, the LULC could explain from 56.9% to 31.6% of the variation in water quality at six buffer zones (from 500 m to 1800 m). Forest land had a positive effect on water quality among most buffer zones, while construction land and bare land affected the representative water quality indicators negatively within the 1200 m and 1500 m buffer zones, respectively. There was also a seasonal variation in the relationship between LULC and water quality. The closest connection between them appeared at the 1000 m buffer zone in the dry season, whereas there was no significant difference among the buffer zones in the wet season. The results suggest the importance of considering buffer-zone scales in assessing the impacts of LULC on water quality in urban lakeshore areas.