Building national eco-cultural protection areas and the Xiangxi practice in Hunan Province     

Liu  Chunla  Wu  Liping  Xu  Mei  Zeng  Fanchao  Jiao  Lipeng 《地理学报(英文版)》2020,30(12):2076-2092

Journal of Geographical Sciences - Since 2007, the Chinese government has initiated the building of national eco-cultural protection areas (NECPAs), thereby embarking on a significant...  相似文献   

A note on the lake level variations of Nam Co,south-central Tibetan Plateau from 2005 to 2019     

ShiQiao Zhou 《寒旱区科学》2020,12(6):430-435

Tibetan lake levels are sensitive to global change, and their variations have a large impact on the environment, local agriculture and animal husbandry practices. While many remote sensing data of Tibetan lake level changes have been reported, few are from in-situ measurements. This note presents the first in-situ lake level time series of the central Tibetan Plateau. Since 2005, daily lake level observations have been performed at Lake Nam Co, one of the largest on the Tibetan Plateau. The interannual lake level variations show an overall increasing trend from 2006 to 2014, a rapid decrease from 2014 to 2017, and a surge from 2017 to 2018. The annual average lake level of the hydrological year (May-April) rose 66 cm from 2006 to 2014, dropped 59 cm from 2014 to 2017, and increased 20 cm from 2017 to 2018, resulting in a net rise of 27 cm or an average rate of about 2 cm per year. Compared to the annual average lake level based on the calendar year, it is better to use the annual average lake level based on the hydrological year to determine the interannual lake level changes. As the lake level was stable in May, it is appropriate to compare May lake levels when examining interannual lake level changes with fewer data. Overall, remote sensing results agree well with the in-situ lake level observations; however, some significant deviations exist. In the comparable 2006-2009 period, the calendar-year average lake level observed in-situ rose by 10-11 cm per year, which is lower than the ICESat result of 18 cm per year.  相似文献   

喜马拉雅中部甘达基河流域尼泊尔国鸟(棕尾虹雉)生境分布变化     

Raju RAI  Basanta PAUDEL  谷昌军  Narendra Raj KHANAL 《资源与生态学报(英文版)》2020,11(2):223-231

甘达基河流域(Gandaki River Basin,GRB)是喜马拉雅中部地区的一部分,该地区栖息着许多珍稀的野生动物。由于气候和人类活动的影响,许多珍稀保护物种的生境处于危险之中。本研究基于最大熵(MaxEnt)模型,运用生物气候、土地覆被和DEM数据,分析各环境要素对棕尾虹雉(Lophophorusimpejanus)的生境适宜性的影响,评估棕尾虹雉现在状况和未来栖息地分布的变化。研究表明,目前棕尾虹雉的高度适宜栖息地面积约为749 km^2,主要分布在流域北部、东部和西部,尤其是郎塘国家公园、马纳斯卢峰自然保护区和安纳布尔纳峰自然保护区等保护区内。到2050年,棕尾虹雉的高度适宜栖息地面积将减少至561 km^2,主要在流域北部和西北部(即Chhyo,Tatopani,Humde和Chame地区)。未来环境变化的模拟表明,由于适宜栖息地面积的减少,棕尾虹雉面临的生存风险将增加。  相似文献   

近期长江大通至南京河段潮动力变化趋势与机制     

袁小婷  程和琴  郑树伟  石盛玉  马玉改 《海洋通报》2019,38(5):553-561

近期长江感潮河段径、潮动力已然发生变化,但其变化机制与趋势有待进一步探讨。通过对长江大通至南京河段的野外调查,并分析了近40年来大通、芜湖和南京站水文资料,探讨了近期该河段的潮动力变化机制与趋势。结果表明:近年来长江大通至南京段潮动力有增强趋势。具体表现为相近径流量条件,潮差平均增大约10 cm,主要分潮振幅增加10%～30%,潮汐形态系数有减小趋势。引起上述变化的原因可能有:(1)近期感潮河段整体冲刷变深导致潮波上溯阻力减小;(2)口外潮汐动力增强以及海平面上升等使潮汐上溯能力增强。此外,长江流域修建了大量水库群,导致该河段径流量变化由自然因素主导变成自然与人为调控共同作用为主,从而影响了潮动力的相对强弱。  相似文献   

我国海洋保护地现状、问题及发展对策          下载免费PDF全文

赵林林  程梦旎  应佩璇  曲方圆  张朝晖 《海洋开发与管理》2019,36(5):3-7

随着我国海洋经济的不断发展,沿海地区的海洋环境和生态系统面临的压力不断加剧。海洋保护地作为海洋生态环境管理的有效手段,近30年来被广泛应用于海洋生物多样性和生态系统保护,取得了显著的成就和效果。文章通过对我国海洋保护地的建设情况进行系统研究,阐述了海洋保护地的发展现状和管理体制,重点剖析了海洋保护地管理和建设过程中面临的缺乏顶层设计、管理能力和管护条件弱、管理人才和资金少、空间发展不平衡等问题,在建设以国家公园为主体的自然保护地体系的新形势下,为我国海洋保护地的发展提出了健全海洋保护地管理制度体系、构建海洋保护地网络体系、加强海洋保护地管理能力建设和加强海洋保护地宣传教育等对策建议。  相似文献   

青海湖流域植被盖度时空变化研究     

高黎明  张乐乐 《地球信息科学学报》2019,21(9):1318-1329

高寒区植被变化一直是气候和生态学领域关注的热点问题。本研究基于MODIS NDVI数据计算的植被覆盖度数据和高分辨率气象数据,分析了青海湖流域2001-2017年植被覆盖度分布格局及动态变化,探讨了其对气候变化、人类活动和冻土退化的响应。结果表明：① 近十几年青海湖流域植被覆盖度整体表现为增加趋势,不同植被类型增幅存在差异性,草地增幅最大,达到6.1%/10a,其它植被类型增幅在2%~3%/10a之间;② 流域局部地区仍存在植被退化现象,研究期植被退化面积表现为先增加后减小的变化趋势。2006-2011年重度退化区集中在青海湖东岸,2011-2017年重度退化区集中在流域的西北部,这些区域是青海湖流域荒漠分布区,植被覆盖度较低,是今后生态恢复需重点关注的区域;③ 气候变化是流域植被覆盖度变化的主导因素,气候变化对青海湖流域主要植被类型覆盖度变化的贡献率为84.21%,对草原、草甸和灌丛植被覆盖度变化的贡献率分别为81.84%、87.47%和75.96%;④ 人类活动对流域主要植被类型覆盖度变化的贡献率为15.79%,对草原、草甸和灌丛植被覆盖度变化的贡献率分别为18.16%、12.53%和24.04%,环青海湖地区人类活动对植被恢复有促进效应,在青海湖流域北部部分地区人类活动的破坏力度仍大于建设力度;⑤ 冻土退化对青海湖流域草甸和灌丛植被覆盖度变化影响很小,主要影响草原植被覆盖度变化,冻土退化造成草原植被覆盖度增长速率减小了1.2%/10a。  相似文献   

Microseism Variations in Response to Antarctic Seasonal Changes in Sea Ice Extent     

XU Xiaoqing  LIN Jianmin  FANG Sunke 《中国地震研究》2020,34(2):264-284

The temporal and spatial distributions of Antarctic sea ice play important roles in both the generation mechanisms and the signal characteristics of microseisms. This link paves the way for seismological investigations of Antarctic sea ice. Here we present an overview of the current state of seismological research about microseisms on Antarctic sea ice. We first briefly review satellite remote-sensing observations of Antarctic sea ice over the past 50 years. We then systematically expound upon the generation mechanisms and source distribution of microseisms in relation to seismic noise investigations of sea ice, and the characteristics of Antarctic microseisms and relationship with sea ice variations are further analyzed. We also analyze the continuous data recorded at seismic station BEAR in West Antarctica from 2011 to 2018 and compare the microseism observations with the corresponding satellite remote-sensing observations of Antarctic sea ice. Our results show that:(1) the microseisms from the coastal regions of West Antarctica exhibit clear seasonal variations, SFM with maximum intensities every April-May and minimum intensities around every October-November; while DFM intensities peak every February-March, and reach the minimum around every October. Comparatively, the strong seasonal periodicity of Antarctic sea ice in better agreement with the observed DFM; and (2) microseism decay is not synchronous with sea ice expansion since the microseism intensity is also linked to the source location, source intensity (e.g., ocean storms, ocean wave field), and other factors. Finally, we discuss the effect of Southern Annular Mode on Antarctic sea ice and microseisms, as well as the current limitations and potential of employing seismological investigations to elucidate Antarctic sea ice variations and climate change.  相似文献   

Perceptual models of uncertainty for socio-hydrological systems: a flood risk change example     

Ida K. Westerberg  Keith J. Beven  Gemma Coxon  Tobias Krueger 《水文科学杂志》2020,65(Z2):1705-1713

ABSTRACT

Characterizing, understanding and better estimating uncertainties are key concerns for drawing robust conclusions when analyzing changing socio-hydrological systems. Here we suggest developing a perceptual model of uncertainty that is complementary to the perceptual model of the socio-hydrological system and we provide an example application to flood risk change analysis. Such a perceptual model aims to make all relevant uncertainty sources – and different perceptions thereof – explicit in a structured way. It is a first step to assessing uncertainty in system outcomes that can help to prioritize research efforts and to structure dialogue and communication about uncertainty in interdisciplinary work.  相似文献   

高分三号SAR影像双阈值变化检测   总被引：1，自引：1，他引：0  

崔斌  张永红  闫利  魏钜杰 《遥感学报》2020,24(1):1-10

双阈值合成孔径雷达SAR(Synthetic Aperture Radar)变化检测算法具有在发现变化区域的同时还能确定地表发生后向散射变化类型的优点。针对广义高斯双阈值最小误差法D-GKIT(Dual Generalized Kittler and Illingworth Thresholding)在进行阈值选取时直方图中不同类别像素灰度级重叠严重时,分割结果容易在尖峰单侧选取出双阈值而导致无法正确分割差异图的问题,本文提出一种结合归一化最大类间方差和广义高斯最小误差法GKIT(Generalized Kittler and Illingworth Thresholding)的双阈值SAR变化检测方法。首先,提出以归一化最大类间方差值作为灰度级重叠程度的判别参数,确定阈值的选取顺序及两个候选区间;然后,利用GKIT在候选区间内进行分割,获取单侧阈值及非变化类拟合函数;最后,提出利用非变化类拟合函数更新后的直方图作为另一侧阈值选取基础进行分割,得到对应分割阈值。以宁波地区高分三号(GF-3)SAR卫星影像作为试验研究数据,结果表明:本文方法能较好地解决灰度级重叠时D-GKIT无法进行正确分割的问题,具有良好的变化检测效果和更强的鲁棒性且达到了利用研究区数据验证利用GF-3号SAR卫星影像进行变化检测研究可行性的目的。  相似文献   

2013年芦山地震震源区地壳介质地震波速变化的特征分析          下载免费PDF全文

王俊  郑定昌  张金川  詹小艳  钱婷 《地球物理学报》2020,63(2):517-531

为探究芦山M7.0级地震后5年多来，震源区龙门山断裂带西南段介质波速的变化规律，本文基于2012年4月至2018年4月共6年的连续波形数据，运用移动窗互谱与频域偏振等分析方法，结合背景噪声源的特性，对不同深度范围内的相对波速变化以及震后的恢复过程与机制进行了研究.获得的主要认识包括：（1）年尺度而言，震源区周期为1~20 s的背景噪声场相对稳定，但成分复杂、2~10 s频带内至少存在2个能量相对稳定的噪声源；不同周期噪声的能量，在月变与季节性上的变化特征差异明显.（2）获得了长时间尺度、不同频带内介质相对波速的背景变化水平，1~2 s、2~4 s的波动幅度（约为±0.04%）与季节性变化规律强于4~10 s、10~20 s的，结合与降雨量相关的地下水位模型能很好地解释其变化规律.（3）震源区的同震波速降低现象清晰，降幅约为0.08%~0.1%；空间上，波速下降最为显著的区域主要集中在龙门山断裂带两侧约70 km范围内，其中四川盆地一侧平均约为0.1%，略高于青藏高原（0.08%）一侧；在断裂带内的降速不显著.对不同子频带进行测量的结果显示，震后除10~20 s外，其余3个子频带的相对波速在震后较短时间内（约20天左右）均出现较大幅度的波速降低现象，其中4~10 s的平均降速最大（约为0.08%），分析认为主震及大量余震的松弛效应是引起介质波速下降的主要原因.（4）震后大约1年左右，波速变化基本恢复到震前水平，且至2018年4月前未观察到大幅的波速变化现象，总体上各频带内的结果均沿零线小幅波动.  相似文献