Potential benefits of increased application of water to paddy fields in Taiwan     

Yu‐Chuan Chang  Chun‐E. Kan  Gwo‐Fong Lin  Chao‐Lin Chiu  Yuan‐Chuan Lee 《水文研究》2001,15(8):1515-1524

The potential benefits of increased application of water to paddy fields in Taiwan are investigated in this paper. A conceptual model is used to represent the hydrological system of the paddy field. A technique is presented to estimate the parameters of the model. Field experiments also are performed for parameter estimation and model verification. The simulated results are in good agreement with the observed during model verification. With parameters estimated from the field data, the model is used to simulate the effects of applying water beyond current practice. The simulation results show that the downward percolation increases when the irrigation water increases. However, the percolation reaches a capacity rate no matter how large the amount of water applied. This phenomenon results from the existence of a hard layer below the paddy field. The effects of raising the height of levees around paddy fields are also studied. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

山东省矿产资源形势与对策          下载免费PDF全文

刘玉强  王传才  吕昶  游文澄 《山东国土资源》2002,18(3):65-71

山东省属于矿产资源中等丰富的省份.但人均占有量相对较小.矿产资源勘查程度较高,在开发中还存在着一些问题亟需解决.根据本省的资源情况,要充分利用国内外资金、资源和市场,以保障全省国民经济发展的需要.  相似文献   

THE DYNAMIC MONITORING OF HORQIN SAND LAND USING REMOTE SENSING     

HUYuan－man  JIANGYan 《中国地理科学(英文版)》2002,12(3):238-243

Hurqin Sand Land is regarded as the typical region for studying the problem of desertification.The integra-tion of 3S(GIS,GPS and RS)techniques offer a most helpful method to study and monitor the dynamics of desertification.Based on the data derived from 3 periodsˊmultitemporal Landsat TM imagery of the 1990s,the regional land use and dynamo-ics of desertification in Horqin Sand Land were studied.The main results revealed that :1)as long as the general change tendency was concerned,the desertification of Horqin Sand Land would continue to spread;2)there was a gradual de-crease in the area of both moving sand dunes and semi-stabilized ones,which meant that fruitful progress had been made to control the desertification during the 1990s;3)as a result of unreasonable cultivation,the total area of stabilized sand dunes and grassland in the middle and western region decreased obviously.It suggested that the increasing damage caused by human was leading to the hazard of further desertification.So in the future,it is necessary to take more effect-tive measures to control the spread of desertification and restore the degraded ecosystems for the purpose of optimizing the global eco-environment in Horqin Sand Land.  相似文献   

Rapid neutral–neutral reactions at low temperatures: a new network and first results for TMC-1     

Ian W. M. Smith  Eric Herbst  Qiang Chang 《Monthly notices of the Royal Astronomical Society》2004,350(1):323-330

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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   

Prediction and verification of earthquakes induced by the Xiluodu hydropower station reservoir          下载免费PDF全文

Tinggai Chang  Baohua Li  Xinxiang Zeng 《地震科学（英文版）》2022,35(5):387-397

Research has been conducted on reservoir-induced earthquakes in China since the Xinfengjiang reservoir-induced earthquakes in the 1960s. Regulations now require the risk of reservoir-induced earthquakes to be evaluated in the pre-research stage of all hydropower projects. Although nearly 40 cases of reservoir-induced earthquakes have been reported in China, analyses comparing the changes in seismic activity following reservoir impoundment with predictions are rare. In this study, we compared seismic activities observed in the reservoir area before and after the impoundment of the Xiluodu hydropower station in terms of the spatial distribution, frequency, and focal depths of the earthquakes, and clarified the correlation between their frequency/timing and reservoir level after impoundment. We then concluded that the seismic events in the head region were karst-type earthquakes, while those in the second segment of the reservoir were tectonic earthquakes. The spatial distribution of the earthquake epicenters and the seismic intensities validated some of the results for the reservoir-induced seismic risk assessment for the Xiluodu hydropower station, indicating that the proposed earthquake triggers and predictive models are reasonable. This study can provide a valuable reference for investigating the mechanism (s) of reservoir-induced earthquakes, revising reservoir-induced earthquake hazard assessment codes, and predicting the hazard zones of reservoir-induced seismicity under similar conditions.  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   

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   

河套盆地临河坳陷油气成藏过程解剖及勘探潜力分析     

沈华  刘震  史原鹏  徐泽阳  李拥军  陈树光  王会来  王志成  王标  刘畅 《现代地质》2021,35(3):871-882

河套盆地属于我国中西部地区中小型陆相含油气盆地,近期于临河坳陷西南部吉兰泰构造带发现亿吨级大油田。工区地质条件复杂且勘探程度低,油藏动态演化过程研究有待深化。针对吉西凸起带和中央断垒带已发现油藏,应用地质、地震和分析化验等资料,在石油地质综合分析的基础上,采用“九史”分析方法对油藏进行动态解剖,取得了以下三点认识:(1)油气晚期成藏并表现出“三晚”,即烃源岩晚期生烃、断裂晚期活动及油气晚期充注;(2)第四纪走滑活动影响油气富集,负花状构造不发育且晚期强烈反转地区有利于成藏;(3)优选出西南部凸起带和中央断垒带两大油气有利勘探区带。  相似文献   

Pressure calibration and sound velocity measurement to 12 GPa in multi-anvil apparatus     

Song  Wei  Shan  Shuangming  Tang  Qizhe  Su  Chang  Liu  Yonggang 《中国地球化学学报》2021,40(4):525-531

We performed the pressure calibration to 12 GPa for 14/6 type (octahedron edge length/WC truncated edge length, in mm) cell assembly in DS 6 × 1400 multi-anvil apparatus by using the phase transitions in Bi (I-II 2.55 GPa, III-V 7.67 GPa) and ZnTe (LPP-HPP I 9.6 GPa, HPP I-II 12.0 GPa). As verification and application, sound velocity measurements on polycrystalline Al₂O₃ to 12 GPa at room temperature were conducted and the ultrasonic result is in good agreement with previous reports. It demonstrates the feasibility of performing sound velocity measurements close to the mantle transition zone pressure condition in our laboratory.

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