基于GIS的云南保山小流域土地利用变化研究     

李丹  岳彩荣 《云南地理环境研究》2011,23(4):68-72

随着全球变暖趋势的增强,土地利用变化是全球变化中的重要组成部分。土地利用变化研究尤其是空间变化研究就成为了研究者非常关心的问题。以云南省保山杨柳小流域土地利用变化的实例分析,详细阐述了GIS的空间分析方法及其在土地利用变化研究中的应用。利用转移矩阵研究结果显示:该小流域农地总变化量最大,其次是有林地和荒山,变化最小的是水体和未利用地,有林地和未成林造林地以交换变化为主,水体和居民地净变化为主;从新增的角度来说,农地转化为有林地最具有转换优势,其次是农地转换为荒山;从流失的去向看,牧地转换为农地最具转换优势,其次是农地转换为牧地。  相似文献   

Soil erosion control degree of the project of converting farmland to forest in mountainous areas at China��s Southwest border: A case study in Mangshi, Yunnan Province     

Zisheng Yang  Huali Han  Qiaogui Zhao 《山地科学学报》2011,8(6):845-854

There have been few in-depth quantitative studies on soil erosion control and the ecological effects of land use changes. Soil erosion is the first eco-environmental problem particularly in mountainous areas. A major problem in the conversion of farmland to forest is to control soil erosion and improve ecological environment and thus to improve land use sustainability. We report results of calculation and analysis on soil erosion from converted farmland parcels in city of Mangshi (near the SW frontier of China) and the surrounding areas before and after the nine-year (2000–2009) project of converting farmland to forest. There was increased water conservation effect, as a result of decreased soil erosion. The average erosion modulus of the farmland returning to eco-friendly uses decreased by 5,535.59 t/km²·a and the control degree of soil erosion modulus reached 71.00%. The increased soil erosion after the returning in the typical sample area “did not drop, but increased” as the terraced fields decreased but sloping farmland increased and yet woodland decreased.  相似文献   

2022年1月8日青海门源M_S6.9地震前地磁垂直强度极化异常变化特征          下载免费PDF全文

樊文杰  冯丽丽  李霞  何畅  廖晓峰  姚休义 《地震工程学报》2022,44(3):744-750

基于甘青川地区的14个地磁台站秒采样资料,对2022年1月8日青海门源M_S6.9地震前地磁垂直强度极化异常的时空变化特征进行分析研究。计算结果显示,在2021年10月底出现了地磁极化超阈值高值异常变化,异常台站主要分布在青海、甘肃和四川地区,异常出现后73天发生了门源地震,震中位于极化高值异常阈值线附近。研究还发现,此次地磁极化异常具有一定的时空变化特征,时间上,不同台站极化异常具有较好的时间同步性;空间上,极化异常高值区呈现出沿震中附近出现后不断扩展最终再向震中收缩的特点。此外,各地磁极化异常台站的归一置零极化值、异常持续时间与震中距存在较好的负相关性,异常台站距离地震震中越近,其归一置零极化值越高,异常持续时间也越长,这一特征符合地震电磁扰动信号的衰减特征。根据极化异常和地震的时空关系分析认为,此次地磁极化高值异常对应了之后在异常高值区边缘发生的门源M_S6.9地震。  相似文献   

2021年5月21日漾濞4次M_S≥5.0地震前后b值变化          下载免费PDF全文

曾宪伟  赵小艳  李蒙亚  李文君  唐浩  袁媛 《地震学报》2022,44(3):401-412

2021年5月21日21时21分至22时31分,云南大理州漾濞县接连发生4次M_S≥5.0地震,分别为M_S5.6,M_S6.4,M_S5.0和M_S5.2地震。选取2015年1月1日至2021年6月4日漾濞地震震源区及其附近区域记录的地震资料,利用极大似然法计算研究区b值,通过分析漾濞地震前后不同时段的b值空间分布特征,得到以下主要认识:① 漾濞震群发生后,震源区b值出现快速下降,可能预示着局部地壳介质强度接近临界状态;② 漾濞4次M_S≥5.0地震均沿剖面低b值异常区的边缘分布;③ 漾濞地震发生后,震源区b值明显回升,预示着地壳应力得到释放,短期强震危险性降低;④ 漾濞地震西北40 km和70 km处存在低b值异常区,未来存在发生中强地震的风险。   相似文献   

2022年1月2日宁蒗M_S5.5地震序列重定位与发震构造分析          下载免费PDF全文

王光明  吴中海  刘昌伟  张天宇  彭关灵 《地震学报》2022,44(4):581-593

2022年1月2日云南省丽江市宁蒗县发生M_S5.5地震。采用地震编目系统提供的此次地震的震相到时数据,使用双差定位方法对此次宁蒗M_S5.5地震序列进行重新定位,获得了694次地震的高精度相对位置。重定位后的地震空间分布显示:此次地震序列呈NNE至近NS向分布,与震源机制解的节面Ⅱ走向（191°）一致,主震位于地震序列南段;地震序列主体活动区长约11 km,宽约6 km,余震主要分布在4—11 km的深度范围内;地震序列在深度剖面上呈现出两组倾向不同的活动分支,其中东侧分支与震源机制解节面Ⅱ的倾角（81°）一致。此外,本次地震还可能触发了邻区的局部断裂活动。综合分析认为,2022年宁蒗M_S5.5地震的发震构造应该是NNE至近NS向兼具正断层分量的左旋走滑断层,倾向为WNW,倾角约为81°,其活动性质与震源区已知的活动断层均不一致。尽管本次宁蒗M_S5.5地震序列发生在2012年宁蒗—盐源M_S5.7地震序列的北侧,但是两次地震序列的发震断层并不相同。库仑应力反演结果显示,2012年宁蒗—盐源M_S5.7地震对本次宁蒗M_S5.5地震的发生具有促进作用。   相似文献   

Performance of the Yangbi MS 6.4 earthquake disaster in different geomorphic units in Yunnan     

Jianlin Li  Zufeng Chang  Changwei Liu 《地震研究进展（英文）》2022,2(2):100135

An M_S 6.4 earthquake occurred in Yangbi, Yunnan province, on May 21, 2021. According to related investigations, the macro-epicenter of the earthquake is 6 km northwest of Yangbi County, and the seismogenic structure is the NW-trending Weixi-Qiaohou fault. The earthquake area is located in the hinterland of the Hengduan Mountains in the northwest of Yunnan province, a region dominated by high and medium-high mountains, with deep canyons and tectonic basins in between. Various geomorphic features are derived from drastic topographic changes and huge geological differences in the earthquake area. There are a variety of buildings in the earthquake-affected zone, including civil and brick-wood structures ones with weak seismic performance, as well as brick-concrete and frame ones with better seismic performance. This paper summarizes and analyzes different characteristics of the earthquake in different geomorphic units through field investigations of different buildings and geological disasters in the affected area. The results show that under the same earthquake intensity, the damage to most buildings (located in slope areas or rooted in weak strata) is amplified by the earthquake. The earthquake has exerted an obvious propagation effect along the direction of the seismogenic structure. Moreover, local ground fissures will aggravate the damage to the buildings even without surface dislocation. Thus, we suggest that attention should be paid to the ground fissures caused by the slope effect. The fissure areas may also be the disaster spot of collapses and landslides in case of a high-magnitude earthquake.  相似文献   

浅谈地震科普讲座中教学三维目标的构建与落实          下载免费PDF全文

李霞 《地震科学进展》2022,(8):396-400

教学三维目标是教育教学过程中应达到的目标维度,包括知识与技能目标、过程与方法目标、情感态度与价值观目标。地震科普讲座作为一种教育教学,也应有相应的教学目的和需要实现的宣传效果。以教学三维目标为引领,设计地震科普讲座,发挥目标提纲挈领的作用,可以有效提升受众对地震灾害的认识、学习、理解和参与能力,从而在地震灾害来临时运用知识解决问题,实现科学避震,保护自我及他人。   相似文献   

A real-time AI-assisted seismic monitoring system based on new nodal stations with 4G telemetry and its application in the Yangbi MS 6.4 aftershock monitoring in southwest China     

Junlun Li  Huajian Yao  Baoshan Wang  Yang Yang  Xin Hu  Lishu Zhang  Beng Ye  Jun Yang  Xiaobin Li  Feng Liu  Guoyi Chen  Chang Guo  Wen Yang 《地震研究进展（英文）》2022,2(2):100033

A rapidly deployable dense seismic monitoring system which is capable of transmitting acquired data in real time and analyzing data automatically is crucial in seismic hazard mitigation after a major earthquake. However, it is rather difficult for current seismic nodal stations to transmit data in real time for an extended period of time, and it usually takes a great amount of time to process the acquired data manually. To monitor earthquakes in real time flexibly, we develop a mobile integrated seismic monitoring system consisting of newly developed nodal units with 4G telemetry and a real-time AI-assisted automatic data processing workflow. The integrated system is convenient for deployment and has been successfully applied in monitoring the aftershocks of the Yangbi M_S 6.4 earthquake occurred on May 21, 2021 in Yangbi County, Dali City, Yunnan in southwest China. The acquired seismic data are transmitted almost in real time through the 4G cellular network, and then processed automatically for event detection, positioning, magnitude calculation and source mechanism inversion. From tens of seconds to a couple of minutes at most, the final seismic attributes can be presented remotely to the end users through the integrated system. From May 27 to June 17, the real-time system has detected and located 7 905 aftershocks in the Yangbi area before the internal batteries exhausted, far more than the catalog provided by China Earthquake Networks Center using the regional permanent stations. The initial application of this integrated real-time monitoring system is promising, and we anticipate the advent of a new era for Real-time Intelligent Array Seismology (RIAS), for better monitoring and understanding the subsurface dynamic processes caused by Earth's internal forces as well as anthropogenic activities.  相似文献   

Expansion dynamics of deciduous rubber plantations in Xishuangbanna,China during 2000–2010     

Weili Kou  Jinwei Dong  Alexander J. Hernandez  Yuanwei Qin  Geli Zhang 《地理信息系统科学与遥感》2018,55(6):905-925

Monoculture rubber plantations have been replacing tropical rain forests substantially in Southern China and Southeast Asia over the past several decades, which have affected human wellbeing and ecosystem services. However, to the best of our knowledge on the extent of rubber plantation expansion and their stand ages is limited. We tracked the spatiotemporal dynamics of deciduous rubber plantations in Xishuangbanna, the second largest natural rubber production region in China, from 2000 to 2010 using time-series data from the Phased Array type L-band Synthetic Aperture Radar (PALSAR), Landsat, and Moderate Resolution Imaging Spectroradiometer (MODIS). We found that rubber plantations have been expanding across a gradient from the low-elevation plains to the high elevation mountains. The areas of deciduous rubber plantations with stand ages ≤5, 6–10, and ≥11-year old were ~1.2 × 10⁵ ha, ~0.8 × 10⁵ ha, and ~2.9 × 10⁵ ha, respectively. Older rubber plantations were mainly located in low-elevation and species-rich regions (500–900 m) and younger rubber trees were distributed in areas of relative high-elevation with fragile ecosystems. Economic and market factors have driven the expansion of rubber plantations, which is not only a threat to biodiversity and environmental sustainability, but also a trigger for climatic disasters. This study illustrates that the integration of microwave, optical, and thermal data is an effective method for mapping deciduous rubber plantations in tropical mountainous regions and determining their stand ages. Our results demonstrate the spatiotemporal pattern of rubber expansions over the first decade of this century.  相似文献   

利用遥感瞬时温度场研究云南山地气温直减率   总被引：3，自引：0，他引：3  

王艳霞  丁琨  黄晓园  龙晓敏  周汝良 《遥感学报》2014,18(4):912-922

基于MODIS影像反演地表瞬时温度场和气象站点30年平均气温实测数据,结合数字高程模型,研究了云南山地气温随海拔变化的规律。结果表明,降低或消除了坡向与坡度、纬度与经度变化的影响后,在云南全区域尺度上,海拔对气温作用而产生的气温直减率为0.53℃;在典型山地地貌类型区,山地气温直减率由高山区向低山区逐渐增大,滇西北高山区直减率为0.47℃,滇中、滇东中山区为0.51℃,滇南宽谷低山区为0.54℃,滇西北高山峡谷和滇南低山深切沟谷地带为0.54℃;由阳坡、半阴半阳坡至阴坡,山地气温直减率依次增大:阳坡直减率平均为0.52℃,半阴半阳坡平均为0.54℃,阴坡平均为0.55℃。除海拔之外,坡向、坡度等微地形因子亦是微格局气温场的主要地理响应因子。利用遥感数据反演的瞬时温度场研究山地气温直减率,是一种研究山地气温变化规律的新方法。  相似文献