There is difficulty for distinguishing of river and shadow in Synthetic Aperture Radar (SAR) images. A method of river segmentation in SAR images based on wavelet energy and gradient is proposed in this paper. It main...There is difficulty for distinguishing of river and shadow in Synthetic Aperture Radar (SAR) images. A method of river segmentation in SAR images based on wavelet energy and gradient is proposed in this paper. It mainly includes two algorithms: coarse segmentation and refined segmen- tation. Firstly, The river regions are coarsely segmented by the wavelet energy feature,and then refined segmented accurately by the gradient threshold which is got adaptively. The experimental results show the validity of the method, which provides a good foundation for targets detection above the river.展开更多
No earthquake of magnitude six or greater has been recorded historically in the southern segment of the Red River Fault(RRF).This absence constitutes a significant seismic gap, suggesting a risk of future strong earth...No earthquake of magnitude six or greater has been recorded historically in the southern segment of the Red River Fault(RRF).This absence constitutes a significant seismic gap, suggesting a risk of future strong earthquakes. The China Earthquake Science Experimental Site intends to conduct drilling exploration in this area, which necessitates improved knowledge of the fault zone's geometric distribution characteristics and deep structure. We obtained and analyzed audio and broadband magnetotelluric(MT) data collected at one of the alternative drilling stations(in the Dazhai Village of Honghe County). We have used these data to obtain a highresolution 3-D electrical model of this study area's subsurface to a depth of 5 km. We report that the electrical structure from the surface to 0.5 km is relatively complex, characterized by alternating high and low resistivity;below 0.5 km, the electrical structure becomes more simplified. The RRF extends northwest-southeast orientation along the high and low resistivity boundary, dipping northeastward. The electrical structure of the Red River Valley, which the fault zone traverses, reveals low resistivity characteristics with a lateral width of up to2 km. This study offers critical electromagnetic constraints that enhance our understanding of the tectonic characteristics of the RRF. The findings will inform and aid in the design of drilling plans for the southern segment of the RRF region.展开更多
The upper reaches of the Yellow River in Sichuan Province are critical area for water conservation and ecological protection in China. However, they are experiencing a range of ecological and environmental challenges,...The upper reaches of the Yellow River in Sichuan Province are critical area for water conservation and ecological protection in China. However, they are experiencing a range of ecological and environmental challenges, including grassland desertification, wetland degradation, and soil erosion, all of which pose significant threats to the environmental sustainability and overall development of the Yellow River Basin. Urbanization can lead to irreversible damage to ecosystems. Therefore, understanding the relationship between urbanization and ecosystems is crucial for fostering sustainable development in the region. With land use and meteorological data in the upper reaches of the Yellow River in Sichuan Province in 2000-2020, and using InVEST model and standardized processing methods, we analyzed the spatiotemporal evolution characteristics of urbanization and four ecosystem services: water conservation, carbon storage, habitat quality, and soil retention. Additionally, we employed the GeoDa bivariate spatial autocorrelation analysis model to reveal the spatial correlations and interactions between urbanization and ecosystems. The results reveal a significant spatial mismatch between urbanization and ecosystem services in the upper Yellow River region of Sichuan Province. While the composite urbanization index decreased from 0.0075 to 0.0042 and remained concentrated in county centers, all ecosystem services showed improvement: water conservation increased from 17.38×10^(9) mm to 23.37×10^(9) mm, carbon storage rose from 936.60 Tg to 938.42 Tg, habitat quality improved from 0.875 to 0.879, and soil retention enhanced from 13.56×10^(8) t to 17.59×10^(8) t. However, these ecological gains were mainly driven by restoration in non-urban southern areas, creating a clear spatial disconnection from urban centers and leading to persistently weak and declining coordination between systems. This spatial decoupling underscores the inadequacy of the current urbanization model in promoting regional ecological synergy. We therefore recommend implementing differentiated zoning strategies: promoting compact development coupled with ecological restoration in county centers, strictly protecting core water conservation and carbon sequestration areas in the southern key ecological zones, and enhancing soilwater conservation and ecological restoration in the vulnerable northern belt, so as to establish an ecological security framework compatible with sustainable urbanization.展开更多
In this paper, the reservoir temperatures of 14 hot spring samples collected from the northern segment of theRed River Fault are calculated by using the mixing-model of SiO2-geothermometer. Based on the features ofres...In this paper, the reservoir temperatures of 14 hot spring samples collected from the northern segment of theRed River Fault are calculated by using the mixing-model of SiO2-geothermometer. Based on the features ofreservoir temperatures and densities of hot springs, the northern segment of the Red River Fault is furtherdivided into 4 sub-segments. The influence of weakening effect of water on seismic activities is discussed fromthe view point of fault-weakening effect of water. It is suggested that the difference in seismic activity between various sub-segments is principally caused by the difference in intensity of the fault-weakening effect ofwater of these sub-segments. The Eryuan sub-segment where the reservoir temperatures are high and the hotsprings are dense corresponds to a slipped region, however, the Jianchuan and Midu sub-segments where thereservoir temperatures are lower and the hot springs are fewer as well as the Dan sub-segment where the hotspring are very few all correspond to locked regions. It is suggested that Dan sub-segment is the riskiest region for strong earthquake preparation, while the possibility for strong earthquake preparation is very little inthe Eryuan sub-segment.展开更多
基金Support by the National Natural Science Foundation of China (NSFC) (No.60472072)the Specialized Research Foundation for the Doctoral Program of Higher Education (No.20040699034)+1 种基金the Aeronautical Science Foundation of China (No.05I53076)the Yellow River Conser-vancy Commission (YRCC) Research on ecological im-provement of the Yellow River (No.2004SZ01-04)
文摘There is difficulty for distinguishing of river and shadow in Synthetic Aperture Radar (SAR) images. A method of river segmentation in SAR images based on wavelet energy and gradient is proposed in this paper. It mainly includes two algorithms: coarse segmentation and refined segmen- tation. Firstly, The river regions are coarsely segmented by the wavelet energy feature,and then refined segmented accurately by the gradient threshold which is got adaptively. The experimental results show the validity of the method, which provides a good foundation for targets detection above the river.
基金supported by research grants from the National Institute of Natural Hazards, MEMC (ZDJ2020-13)the Innovation Team Project from National Institute of Natural Hazards, MEMC (2023-JBKY-59)the National Natural Science Foundation of China (42174093)。
文摘No earthquake of magnitude six or greater has been recorded historically in the southern segment of the Red River Fault(RRF).This absence constitutes a significant seismic gap, suggesting a risk of future strong earthquakes. The China Earthquake Science Experimental Site intends to conduct drilling exploration in this area, which necessitates improved knowledge of the fault zone's geometric distribution characteristics and deep structure. We obtained and analyzed audio and broadband magnetotelluric(MT) data collected at one of the alternative drilling stations(in the Dazhai Village of Honghe County). We have used these data to obtain a highresolution 3-D electrical model of this study area's subsurface to a depth of 5 km. We report that the electrical structure from the surface to 0.5 km is relatively complex, characterized by alternating high and low resistivity;below 0.5 km, the electrical structure becomes more simplified. The RRF extends northwest-southeast orientation along the high and low resistivity boundary, dipping northeastward. The electrical structure of the Red River Valley, which the fault zone traverses, reveals low resistivity characteristics with a lateral width of up to2 km. This study offers critical electromagnetic constraints that enhance our understanding of the tectonic characteristics of the RRF. The findings will inform and aid in the design of drilling plans for the southern segment of the RRF region.
基金supported by the funding provided by the State Key Laboratory of Hydraulics and Mountain River Engineering (SKHL2210)National Natural Science Foundation of China (42171304)the Sichuan Science and Technology Program (2023YFS0380,2023YFS0377,2023NSFSC1989)。
文摘The upper reaches of the Yellow River in Sichuan Province are critical area for water conservation and ecological protection in China. However, they are experiencing a range of ecological and environmental challenges, including grassland desertification, wetland degradation, and soil erosion, all of which pose significant threats to the environmental sustainability and overall development of the Yellow River Basin. Urbanization can lead to irreversible damage to ecosystems. Therefore, understanding the relationship between urbanization and ecosystems is crucial for fostering sustainable development in the region. With land use and meteorological data in the upper reaches of the Yellow River in Sichuan Province in 2000-2020, and using InVEST model and standardized processing methods, we analyzed the spatiotemporal evolution characteristics of urbanization and four ecosystem services: water conservation, carbon storage, habitat quality, and soil retention. Additionally, we employed the GeoDa bivariate spatial autocorrelation analysis model to reveal the spatial correlations and interactions between urbanization and ecosystems. The results reveal a significant spatial mismatch between urbanization and ecosystem services in the upper Yellow River region of Sichuan Province. While the composite urbanization index decreased from 0.0075 to 0.0042 and remained concentrated in county centers, all ecosystem services showed improvement: water conservation increased from 17.38×10^(9) mm to 23.37×10^(9) mm, carbon storage rose from 936.60 Tg to 938.42 Tg, habitat quality improved from 0.875 to 0.879, and soil retention enhanced from 13.56×10^(8) t to 17.59×10^(8) t. However, these ecological gains were mainly driven by restoration in non-urban southern areas, creating a clear spatial disconnection from urban centers and leading to persistently weak and declining coordination between systems. This spatial decoupling underscores the inadequacy of the current urbanization model in promoting regional ecological synergy. We therefore recommend implementing differentiated zoning strategies: promoting compact development coupled with ecological restoration in county centers, strictly protecting core water conservation and carbon sequestration areas in the southern key ecological zones, and enhancing soilwater conservation and ecological restoration in the vulnerable northern belt, so as to establish an ecological security framework compatible with sustainable urbanization.
文摘In this paper, the reservoir temperatures of 14 hot spring samples collected from the northern segment of theRed River Fault are calculated by using the mixing-model of SiO2-geothermometer. Based on the features ofreservoir temperatures and densities of hot springs, the northern segment of the Red River Fault is furtherdivided into 4 sub-segments. The influence of weakening effect of water on seismic activities is discussed fromthe view point of fault-weakening effect of water. It is suggested that the difference in seismic activity between various sub-segments is principally caused by the difference in intensity of the fault-weakening effect ofwater of these sub-segments. The Eryuan sub-segment where the reservoir temperatures are high and the hotsprings are dense corresponds to a slipped region, however, the Jianchuan and Midu sub-segments where thereservoir temperatures are lower and the hot springs are fewer as well as the Dan sub-segment where the hotspring are very few all correspond to locked regions. It is suggested that Dan sub-segment is the riskiest region for strong earthquake preparation, while the possibility for strong earthquake preparation is very little inthe Eryuan sub-segment.
