scholarly journals Analysis on vegetation cover changes and the driving factors in the mid-lower reaches of Hanjiang River Basin between 2001 and 2015

2021 ◽  
Vol 13 (1) ◽  
pp. 675-689
Author(s):  
Yunjun Zhan ◽  
Jiemeng Fan ◽  
Tingting Meng ◽  
Zhongwu Li ◽  
Yan Yan ◽  
...  
Keyword(s):  
River Basin ◽  
Human Activities ◽  
Vegetation Cover ◽  
Vegetation Change ◽  
Climatic Factors ◽  
Driving Factors ◽  
Jianghan Plain ◽  
Hanjiang River ◽  
The Impact ◽  
Positive Effect

Abstract The mid-lower reaches of the Hanjiang River Basin, located in the core of economic development in Hubei Province, is an integral part of the Yangtze River Economic Belt. In recent years, the watershed ecosystem has become more sensitive to climate changes and human activities, thus affecting the regional vegetation cover. To maintain a stable watershed ecosystem, it is critical to analyze and evaluate the vegetation change and its response to temperature, precipitation, and human activities in this region. This study, based on the trend analysis, partial correlation analysis, and residual analysis, evaluated the change characteristics of vegetation cover as well as the corresponding driving factors in the basin from 2001 to 2015. The results showed that (1) the overall spatial pattern of vegetation cover in the study area was “high in the west and north, lower on both sides of Hanjiang River, and lowest in the center and southeast,” and the pattern changed parabolically with the increasing elevation. (2) Over the 15 years, vegetation cover in the basin showed an increasing trend, and the increased and decreased areas were 90.72 and 9.23%, respectively. (3) The response of vegetation cover to climatic factors varies greatly depending on the increasing elevation. That is, the lag effect under the impact of temperature disappeared gradually, while it became more evident under the impact of precipitation. (4) On the whole, human activities had a positive effect on the regional vegetation cover. The negative effect in the areas around the Nanyang Basin and the positive effect in most parts of the Jianghan Plain were gradually decreased.

scholarly journals Quantifying the Influences of Natural Factors and Human Activities on NDVI Changes in the Hanjiang River Basin, China

2020 ◽  
Vol 12 (22) ◽  
pp. 3780
Author(s):  
Ting Chen ◽  
Jun Xia ◽  
Lei Zou ◽  
Si Hong
Keyword(s):  
River Basin ◽  
Human Activities ◽  
Urban Areas ◽  
Vegetation Index ◽  
Vegetation Coverage ◽  
Vegetation Growth ◽  
Natural Factors ◽  
Range Type ◽  
Hanjiang River ◽  
The Impact

The Hanjiang River Basin (HJRB) is an important source area for drinking water in Hubei Province, China, and the vegetation coverage there is important to the ecological system. Due to the spatial heterogeneity and synergistic effect of various factors, it is very difficult to identify the main factors affecting vegetation growth in the HJRB. With the normalized difference vegetation index (NDVI) data from 2001 to 2018 in the HJRB, the spatiotemporal patterns of NDVI and the influences of natural factors and human activities on NDVI were investigated and quantified based on the Mann-Kendall (M-K) test, partial correlation analysis, and Geographical Detector. The individual factors and their interactions and the range/type of factor attributes suitable for vegetation growth were also examined. NDVI in the HJRB increased from 2001 to 2018, and the variation rate was 0.0046 year−1. NDVI was increasing in 81.17% of the area (p < 0.05). Elevation and slope can effectively explain the vegetation distribution. The interactions of factors on NDVI were significant, and the interactions of the elevation and precipitation can maximize the impact among all factors. The range of available landforms is thought to be highly conducive to vegetation growth. The rates of the annual precipitation and annual mean temperature changed from 2001 to 2018, which were 3.665 mm/year and 0.017 °C/year, and the regions where NDVI positively correlated with them were over 85%. Contrary to the general trend, NDVI has obviously decreased in urban areas since 2010. The quantitative findings of this study can help us better understand the effects of various factors on vegetation growth and provide appropriate suggestions for vegetation protection and restoration in the HJRB.

scholarly journals Vegetation Dynamic Assessment by NDVI and Field Observations for Sustainability of China’s Wulagai River Basin

2021 ◽  
Vol 18 (5) ◽  
pp. 2528
Author(s):  
Panpan Chen ◽  
Huamin Liu ◽  
Zongming Wang ◽  
Dehua Mao ◽  
Cunzhu Liang ◽  
...  
Keyword(s):  
Species Diversity ◽  
River Basin ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Dynamic Assessment ◽  
Indicator System ◽  
Vegetation Changes ◽  
Vegetation Dynamic ◽  
Management Policies ◽  
The Impact

Accurate monitoring of grassland vegetation dynamics is essential for ecosystem restoration and the implementation of integrated management policies. A lack of information on vegetation changes in the Wulagai River Basin restricts regional development. Therefore, in this study, we integrated remote sensing, meteorological, and field plant community survey data in order to characterize vegetation and ecosystem changes from 1997 to 2018. The residual trend (RESTREND) method was utilized to detect vegetation changes caused by human factors, as well as to evaluate the impact of the management of pastures. Our results reveal that the normalized difference vegetation index (NDVI) of each examined ecosystem type showed an increasing trend, in which anthropogenic impact was the primary driving force of vegetation change. Our field survey confirmed that the meadow steppe ecosystem increased in species diversity and aboveground biomass; however, the typical steppe and riparian wet meadow ecosystems experienced species diversity and biomass degradation, therefore suggesting that an increase in NDVI may not directly reflect ecosystem improvement. Selecting an optimal indicator or indicator system is necessary in order to formulate reasonable grassland management policies for increasing the sustainability of grassland ecosystems.

scholarly journals The Long-term Projection of Surface Runoff in the Regions above Danjiangkou in Hanjiang River Basin based on Water-energy Balance

2018 ◽  
Vol 246 ◽  
pp. 01099
Author(s):  
Jun Yin ◽  
Zhe Yuan ◽  
Run Wang
Keyword(s):  
Climate Change ◽  
Energy Balance ◽  
River Basin ◽  
Surface Runoff ◽  
Hydrological Model ◽  
Climatic Factors ◽  
Climate Change Impacts ◽  
Basin Scale ◽  
Hanjiang River ◽  
Distributed Hydrological Models

The projection of surface runoff in the context of climate change is important to the rational utilization and distribution of water resources. This study did a case study in regions above Danjiangkou in Hanjiang River Basin. A basin scale hydrological model was built based on macroscale processes of surface runoff and water-energy balance. This model can describe the quantity relationship among climatic factors, underlying surface and surface runoff. Driven by hypothetical climatic scenarios and climate change dataset coming from CMIP5, the climate change impacts on surface runoff in the regions above Danjiangkou in Hanjiang River Basin can be addressed. The results showed that: (1) Compared with other distributed hydrological models, the hydrological model in this study has fewer parameters and simpler calculation methods. The model was good at simulating annual surface runoff. (2) The surface runoff was less sensitivity to climate change in the regions above Danjiangkou in Hanjiang River Basin. A 1°C increase in temperature might results in a surface runoff decrease of 2~5% and a 10% precipitation increase might result in a streamflow increase of 14~17%. (3) The temperature across the Fu River Basin were projected to increase by 1.4~2.3°C in 1961 to 1990 compared with that in 1961 to 1990. But the uncertainty existed among the projection results of precipitation. The surface runoff was excepted to decrease by 1.3~23.9% without considering the climate change projected by NorESM1-M and MIROC-ESM-CHEM, which was much different from other GCMs.

scholarly journals Vegetation Changes and Their Response to Global Change Based on NDVI in the Koshi River Basin of Central Himalayas Since 2000

2020 ◽  
Vol 12 (16) ◽  
pp. 6644
Author(s):  
Xue Wu ◽  
Xiaomin Sun ◽  
Zhaofeng Wang ◽  
Yili Zhang ◽  
Qionghuan Liu ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
River Basin ◽  
Human Activities ◽  
Vegetation Change ◽  
Precipitation Trend ◽  
Central Himalayas ◽  
Annual Minimum Temperature ◽  
Vegetation Activity ◽  
Koshi River Basin

Vegetation forms a main component of the terrestrial biosphere owing to its crucial role in land cover and climate change, which has been of wide concern for experts and scholars. In this study, we used MODIS (moderate-resolution imaging spectroradiometer) NDVI (Normalized Difference Vegetation Index) data, land cover data, meteorological data, and DEM (Digital Elevation Model) data to do vegetation change and its relationship with climate change. First, we investigated the spatio-temporal patterns and variations of vegetation activity in the Koshi River Basin (KRB) in the central Himalayas from 2000 to 2018. Then, we combined NDVI change with climate factors using the linear method to examine their relationship, after that we used the literature review method to explore the influence of human activities to vegetation change. At the regional scale, the NDVIGS (Growth season NDVI) significantly increased in the KRB in 2000–2018, with significant greening over croplands in KRB in India. Further, the croplands and forest in the KRB in Nepal were mainly influenced by human interference. For example, improvements in agricultural fertilization and irrigation facilities as well as the success of the community forestry program in the KRB in Nepal increased the NDVIGS of the local forest. Climate also had a certain impact on the increase in NDVIGS. A significant negative correlation was observed between NDVIGS trend and the annual minimum temperature trend (TMN) in the KRB in India, but an insignificant positive correlation was noted between it and the total annual precipitation trend (PRE). NDVIGS significantly decreased over a small area, mainly around Kathmandu, due to urbanization. Increases in NDVIGS in the KRB have thus been mainly affected by human activities, and climate change has helped increase it to a certain extent.

scholarly journals Attribution Analysis of Hydrological Drought Risk Under Climate Change and Human Activities: A Case Study on Kuye River Basin in China

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1958 ◽  
Author(s):  
Zhang ◽  
Wang ◽  
Zhou
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Human Activities ◽  
Large Scale ◽  
Research Area ◽  
Drought Severity ◽  
Drought Risk ◽  
Drought Duration ◽  
Recurrence Period ◽  
The Impact

This study conducted quantitative diagnosis on the impact of climate change and human activities on drought risk. Taking the Kuye river basin (KRB) in China as the research area, we used variation point diagnosis, simulation of precipitation and runoff, drought risk assessment, and attribution quantification. The results show that: (1) the annual runoff sequence of KRB changed significantly after 1979, which was consistent with the introduction of large-scale coal mining; (2) under the same drought recurrence period, the drought duration and severity in the human activity stage were significantly worse than in the natural and simulation stages, indicating that human activities changed the drought risk in this area; and (3) human activities had little impact on drought severity in the short duration and low recurrence period, but had a greater impact in the long duration and high recurrence period. These results provide scientific guidance for the management, prevention, and resistance of drought; and guarantee sustainable economic and social development in the KRB.

scholarly journals Impact of Three Gorges Reservoir Water Impoundment on Vegetation–Climate Response Relationship

2020 ◽  
Vol 12 (17) ◽  
pp. 2860
Author(s):  
Mengqi Tian ◽  
Jianzhong Zhou ◽  
Benjun Jia ◽  
Sijing Lou ◽  
Huiling Wu
Keyword(s):  
Human Activities ◽  
Three Gorges Reservoir ◽  
Climatic Factors ◽  
Residual Analysis ◽  
Sensitivity Index ◽  
Climate Response ◽  
Three Gorges ◽  
Response Relationship ◽  
The Impact ◽  
Water Impoundment

In recent years, the impact of global climate change and human activities on vegetation has become increasingly prominent. Understanding vegetation change and its response to climate variables and human activities are key tasks in predicting future environmental changes, climate changes and ecosystem evolution. This paper aims to explore the impact of Three Gorges Reservoir (TGR) water impoundment on the vegetation–climate response relationship in the Three Gorges Reservoir Region (TGRR) and its surrounding region. Firstly, based on the SPOT/VEGETATION NDVI and ERA5 reanalysis datasets, the correlation between climatic factors (temperature and precipitation) and NDVI was analyzed by using partial correlation coefficient method. Secondly, nonlinear fitting method was used to fit the mapping relationship between NDVI and climatic factors. Then, the residual analysis was conducted to evaluate the impact of TGR impoundment on vegetation–climate response relationship. Finally, sensitivity index (SI), sensitivity variation index (SVI) and difference index (DI) were defined to quantify the variation of vegetation–climate response relationship before and after water impoundment. The results show that water impoundment might have some impacts on the response of vegetation–climate, which gradually reduced with increasing distance from the channel; comparing with the residual analysis method, the SI and DI index methods are more intuitive, and combining these two methods may provide new ideas for the study of the impact of human activities on vegetation.

Quantifying the impact of human activities on water quality based on spatialization of social data: a case study of the Pingzhai Reservoir Basin

2020 ◽  
Vol 20 (2) ◽  
pp. 688-699 ◽  
Author(s):  
Yongrong Zhang ◽  
Zhongfa Zhou ◽  
Haotian Zhang ◽  
Yusheng Dan
Keyword(s):  
Water Quality ◽  
River Basin ◽  
Human Activities ◽  
Water Environment ◽  
Oxygen Demand ◽  
Pollution Source ◽  
Pollution Load ◽  
Social Data ◽  
Reservoir Basin ◽  
The Impact

Abstract In water pollution source research, it is difficult to quantify the impact of human activities on water quality. Based on pollution load theory and the concept of spatialization of social data, this study integrates land-use type, slope gradient, and spatial position, and uses the contribution of human activities to quantify the impact of farmland fertilizers, livestock and poultry wastes, and human domestic pollution on water quality in the study area. The results show that livestock manure is the largest source of total phosphorus (TP) and total nitrogen (TN) discharges in the research area, and domestic pollution is the largest source of chemical oxygen demand (COD) discharges. The total equal standard pollution load (as well as the load of each pollution source and its pollutant amount) is the highest in the Nayong River Basin and the lowest in the Baishui River Basin. The contributions of human activities to TP and TN have similar spatial distributions. The impact of human activities on COD discharge is minimal. The quantitative results of this model are basically consistent with the actual conditions in the Pingzhai Reservoir Basin, which suggests that the model reasonably reflects the impact of human activities on the water environment of the basin.

scholarly journals Copula-Based Abrupt Variations Detection in the Relationship of Seasonal Vegetation-Climate in the Jing River Basin, China

2019 ◽  
Vol 11 (13) ◽  
pp. 1628 ◽  
Author(s):  
Jing Zhao ◽  
Shengzhi Huang ◽  
Qiang Huang ◽  
Hao Wang ◽  
Guoyong Leng ◽  
...  
Keyword(s):  
River Basin ◽  
Human Activities ◽  
Urban Areas ◽  
Large Scale ◽  
Vegetation Index ◽  
Climatic Factors ◽  
Potential Evapotranspiration ◽  
Change Points ◽  
Vegetation Coverage ◽  
The Relationship

Understanding the changing relationships between vegetation coverage and precipitation/temperature (P/T) and then exploring their potential drivers are highly necessary for ecosystem management under the backdrop of a changing environment. The Jing River Basin (JRB), a typical eco-environmentally vulnerable region of the Loess Plateau, was chosen to identify abrupt variations of the relationships between seasonal Normalized Difference Vegetation Index (NDVI) and P/T through a copula-based method. By considering the climatic/large-scale atmospheric circulation patterns and human activities, the potential causes of the non-stationarity of the relationship between NDVI and P/T were revealed. Results indicated that (1) the copula-based framework introduced in this study is more reasonable and reliable than the traditional double-mass curves method in detecting change points of vegetation and climate relationships; (2) generally, no significant change points were identified during 1982–2010 at the 95% confidence level, implying the overall stationary relationship still exists, while the relationships between spring NDVI and P/T, autumn NDVI and P have slightly changed; (3) teleconnection factors (including Arctic Oscillation (AO), Pacific Decadal Oscillation (PDO), Niño 3.4, and sunspots) have a more significant influence on the relationship between seasonal NDVI and P/T than local climatic factors (including potential evapotranspiration and soil moisture); (4) negative human activities (expansion of farmland and urban areas) and positive human activities (“Grain For Green” program) were also potential factors affecting the relationship between NDVI and P/T. This study provides a new and reliable insight into detecting the non-stationarity of the relationship between NDVI and P/T, which will be beneficial for further revealing the connection between the atmosphere and ecosystems.

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