scholarly journals Flood-Landscape Ecological Risk Assessment under the Background of Urbanization

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1418 ◽  
Author(s):  
Yuan ◽  
Fang ◽  
Yan ◽  
Sui ◽  
Ding ◽  
...  
Keyword(s):  
Ecological Risk ◽  
Landscape Pattern ◽  
Large Scale ◽  
Risk Index ◽  
Structural Features ◽  
Watershed Scale ◽  
Landscape Pattern Metrics ◽  
Basin Scale ◽  
Landscape Ecological ◽  
Landscape Patches

The Hydrologic Modeling System (HEC-HMS) and statistical analysis method were used to analyze the relationship between flood eigenvalues (i.e., flood volume and peak flow) and landscape pattern metrics. Then, the flood-landscape ecological risk index (ERI_FL) was proposed and constructed to quantitatively assess the flood-landscape ecological risk (FLER). The semivariogram method was used to spatialize the ERI_FL values. Lastly, this study analyzed the spatial–temporal change of FLER at watershed scale and at sub-basin scale, respectively. Two historical landscape distributions (i.e., 2003 and 2017) of Qinhuai River basin were used to perform this study. The results showed that there were certain relationships between landscape pattern and flood eigenvalues, and for different landscapes, the response metrics and degrees were different. FLER increased as urbanization increased. FLER change magnitude had a positive relationship with urban land percentage change magnitude. The distribution of FLER and the distribution of FLER change both showed spatial differences at watershed scale. The structural features of landscape pattern had significant effects on regional floods. In the urbanization process, avoiding forming large-scale landscape patches, improving landscape abundance, and increasing contact area between different types of landscape patches were helpful to reduce the negative effects caused by the increase of urban landscape area on flood.

scholarly journals Effects of Urbanization Expansion on Landscape Pattern and Region Ecological Risk in Chinese Coastal City: A Case Study of Yantai City

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Di Zhou ◽  
Ping Shi ◽  
Xiaoqing Wu ◽  
Jinwei Ma ◽  
Junbao Yu
Keyword(s):  
Land Use ◽  
Ecological Risk ◽  
Landscape Pattern ◽  
Risk Index ◽  
Ecological Risk Index ◽  
Landscape Pattern Metrics ◽  
Pattern Metrics ◽  
Intensity Index ◽  
Yantai City ◽  
Landscape Ecological

Applied with remote sensing, GIS, and mathematical statistics, the spatial-temporal evolution characteristics of urbanization expansion of Yantai city from 1974 to 2009 was studied. Based on landscape pattern metrics and ecological risk index, the landscape ecological risk from the landscape pattern dynamics was evaluated. The results showed that the area of urban land increased by 189.77 km2with average expansion area of 5.42 km2 y−1from 1974 to 2009. The urbanization intensity index during 2004–2009 was 3.92 times of that during 1974–1990. The land use types of urban land and farmland changed greatly. The changes of landscape pattern metrics for land use patterns indicated that the intensity of human activities had strengthened gradually in study period. The landscape ecological risk pattern of Yantai city shaped half-round rings along the coastline. The ecological risk index decreased with increase of the distance to the coastline. The ratio of high ecological risk to subhigh ecological risk zones in 2009 was 2.23 times of that in 1990. The significant linear relationship of urbanization intensity index and regional ecological risk indicated that the anthropological economic activities were decisive factors for sustainable development of costal ecological environment.

scholarly journals Trace element contamination in the mine-affected stream sediments of Oued Rarai in north-western Tunisia: a river basin scale assessment

2021 ◽  
Author(s):  
Jamel Ayari ◽  
Maurizio Barbieri ◽  
Yannick Agnan ◽  
Ahmed Sellami ◽  
Ahmed Braham ◽  
...  
Keyword(s):  
Trace Elements ◽  
Ecological Risk ◽  
Risk Index ◽  
Potential Ecological Risk ◽  
Stream Sediments ◽  
Anthropogenic Sources ◽  
Contamination Level ◽  
North East ◽  
Basin Scale ◽  
North Western

AbstractHigh-quality and accurate environmental investigations are essential for the evaluation of contamination and subsequent decision-making processes. A combination of environmental geochemical indices, multivariate analyses and geographic information system approach was successfully used to assess contamination status and source apportionment of trace elements (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, V and Zn) in surface stream sediments from the Oued Rarai basin in north-western Tunisia, containing various metal and metalloid ores. The contamination level reported in this study indicates a non-negligible potential ecological risk, mainly related to sediment transport along the river. Antimony (concentrations ranged from 0.02 to 297 mg kg−1 and Igeo > 5), arsenic (from 0.5 to 1490 mg kg−1 and Igeo > 5), lead (from 2.9 to 5150 mg kg−1 and Igeo > 5) mercury (from 0.05 to 54.4 mg kg−1 and Igeo > 5) and silver (from 0.05 to 9.4 mg kg−1 and Igeo > 5) showed the most crucial contamination. Besides, potential ecological risk index values were maximum for arsenic with a median of 302, indicating a very high to serious ecological risk (> 160). Results from correlation analysis and principal component analysis revealed three main geochemical associations related to lithologic, tectonic and anthropogenic sources. V, Cr and Cu mainly originated from natural bedrock and soil. Ag and Cd were more controlled by both natural and mining enrichments. Mercury and Pb were mostly influenced by the ancient ore-related activities at the Oued Rarai site and north-east–south-west trending faults. Finally, Sb, As, Ni and Zn were largely controlled by the siliciclastic continental Neogene sequences. Finally, the physical and chemical dynamics of the watershed system, lithological properties, mineralisation, tectonic settings and mobilisation of subsurface sediments largely controlled both concentrations and spatial patterns of trace elements in the study basin. These results need to be considered in the strategies of suitable environmental management at former and current mining sites in north-western Tunisia.

scholarly journals Exploring Variability in Landscape Ecological Risk and Quantifying Its Driving Factors in the Amu Darya Delta

2019 ◽  
Vol 17 (1) ◽  
pp. 79
Author(s):  
Tao Yu ◽  
Anming Bao ◽  
Wenqiang Xu ◽  
Hao Guo ◽  
Liangliang Jiang ◽  
...  
Keyword(s):  
High Risk ◽  
Crop Yield ◽  
Ecological Risk ◽  
Risk Index ◽  
Driving Factors ◽  
Road Density ◽  
Amu Darya ◽  
Risk Areas ◽  
Landscape Ecological ◽  
Gwr Model

Examining the drivers of landscape ecological risk can provide scientific information for planning and landscape optimization. The landscapes of the Amu Darya Delta (ADD) have recently undergone great changes, leading to increases in landscape ecological risks. However, the relationships between landscape ecological risk and its driving factors are poorly understood. In this study, the ADD was selected to construct landscape ecological risk index (ERI) values for 2000 and 2015. Based on a geographically weighted regression (GWR) model, the relationship between each of the normalized difference vegetation index (NDVI), land surface temperature (LST), digital elevation model (DEM), crop yield, population density (POP), and road density and the spatiotemporal variation in ERI were explored. The results showed that the ERI decreased from the periphery of the ADD to the centre and that high-risk areas were distributed in the ADD’s downstream region, with the total area of high-risk areas increasing by 86.55% from 2000 to 2015. The ERI was spatially correlated with Moran’s I in 2000 and 2015, with correlation of 0.67 and 0.72, respectively. The GWR model indicated that in most ADD areas, the NDVI had a negative impact on the ERI, whereas LST and DEM had positive impacts on the ERI. Crop yield, road density and POP were positively correlated with the ERI in the central region of the ADD, at road nodes and in densely populated urban areas, respectively. Based on the findings of this study, we suggest that the ecological constraints of the aforementioned factors should be considered in the process of delta development and protection.

scholarly journals Assessing Vegetation Dynamics and Landscape Ecological Risk on the Mainstream of Tarim River, China

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2156
Author(s):  
Hui Zhang ◽  
Lianqing Xue ◽  
Guanghui Wei ◽  
Zengchuan Dong ◽  
Xianyong Meng
Keyword(s):  
Ecological Risk ◽  
Vegetation Index ◽  
Risk Index ◽  
Critical Role ◽  
Vegetation Coverage ◽  
Risk Level ◽  
Tarim River ◽  
Tarim River Basin ◽  
The Tarim River ◽  
Landscape Ecological

The Tarim River (TR), the longest inland river at an arid area in China, plays a critical role in the sustainable development of the regional ecological environment. This study presents the spatial-temporal variations in the vegetation coverage at regional and pixel scales and its driving factors on the TR mainstream. The latest dataset of normalized difference vegetation index (NDVI) and a vegetation coverage index (fc) over the period from 2000–2015 were analyzed with the unary linear regression and the partial correlation. On the basis of land use data, we further built the landscape ecological risk index and assessed the ecological risk level of the mainstream. Our results suggest that the vegetation coverage index demonstrated fluctuations but denoted a generally upward trend in the TR mainstream, the vegetation improvement areas are far greater than the degraded areas during the study period. Apparently, the overflow days in the TR mainstream and the cumulative amount of water transport are the two main factors that dominate the vegetation coverage. The ecological risk level varies throughout the TR with a high-to-low spatial distribution from upstream to downstream, and the overall landscape ecological risk of the whole basin exhibits an upward tendency. Above all, our study provides a framework with the remote sensing data to assess vegetation coverage and landscape ecological risk which can help design and implement reliable strategies for the ecological management and vegetation restoration in the Tarim River Basin.

scholarly journals Study of marsh wetland landscape pattern evolution on the Zoigê Plateau due to natural/human dual-effects

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9904
Author(s):  
Liqin Dong ◽  
Wen Yang ◽  
Kun Zhang ◽  
Shuo Zhen ◽  
Xiping Cheng ◽  
...  
Keyword(s):  
Landscape Pattern ◽  
Human Activities ◽  
Large Scale ◽  
Initial Increase ◽  
Natural Factor ◽  
Wetland Landscape ◽  
Marsh Wetland ◽  
Zoigê Plateau ◽  
Landscape Patches ◽  
Zoige Plateau

Zoigê Plateau, China’s largest plateau marsh wetland, has experienced large-scale degradation of the marsh wetland and evolution of the wetland landscape pattern over the past 40 years due to climate warming and human activities. How exactly do the wetland landscape pattern characteristics change? How do climatic change and human activities affect the wetland evolution? These questions are yet to be systematically investigated. In order to investigate changes to the marsh wetland on the Zoigê Plateau, field investigations, spatial and statistical analysis were undertaken. Findings from our study indicate that from 1977–2016, the area of marsh wetland on the Plateau reduced by 56.54%, approximately 66,700 hm2 of marsh wetland has been lost. The centroids of both marsh and marshy meadow migrated and the landscape centroid migration behaviors were also correlated with the distribution and variation of the marsh wetland on different slopes. In addition, the number of marsh landscape patches initially increased before decreasing; the number of marshy meadow landscape patches also recorded an initial increase, followed by a decline before a final increase. As the effects of human activities weakened, the aggregation degrees of both marsh and marshy meadow increased. Overall, the fragmentation degree, diversity and fractal dimension of the marsh wetland all declined. An investigation into the driving factors affecting the Plateau area shows that the increase of annual average temperature was the natural factor while trenching and overgrazing were the main human factors resulting in wetland degradation. Results from this study provide basic data and theoretical foundation for the protection and restoration of marsh wetland in alpine regions.

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