潍坊沿海潮位分析研究

风暴潮对人类的危害,主要是产生了超过正常风暴潮高位。一般来说风暴潮的危害程度主要反映在潮位上。因此,确定符合实际的高潮位,并进行频率分析是预防风暴潮危害,实施防潮为主的重要依据。 潍坊北部沿海地区包括寿光市、昌邑市、寒亭区、海化区属渤海海域,海岸线自小清河南岸经弥河口、白浪河口、潍河口直到胶莱河入海口。

闽江下游自岩潭潮位分析

闽江下游南北港汇合处的白岩潭是洪水、潮水交替影响区,其潮位是闽江洪水北港水面线的推算起始水位,它的大小对地处北港的福州市防洪工程有着极其重要的意义,所以本文通过对感潮区内白岩潭三十六年实测潮位资料的分析统计,着重就闽江出现大洪水与白岩潭高潮位同时遭遇的可能性和潮水位变化情况,用纯概率统计法和概率结合实际统计法把大洪水和高潮位看成是两个独立的随机变量,在洪、湖产生的时间范围内,分析计算出不同频率情况下,闽江洪水的起始推算水位——白岩潭潮水位的取值问题,供讨论参考。

基于图示法的温涌流域潮洪遭遇组合分析

在河涌整治中,为解决凤凰城—翡翠绿洲片区的防洪排涝问题,现采用定性分析法对温涌流域进行潮洪遭遇分析,以确定其排涝调蓄方案。选取相邻测站水文资料,以近年来的三次极端天气资料为研究对象,分析不同暴雨情况下该流域的潮位变化情况,采用组合图示方法表达了潮洪遭遇相关性。研究表明温涌流域若以内洪为主的遭遇组合对流域防洪排涝安全更为不利,温涌流域在虽然能够抵抗外洪能力,但整体而言蓄排内洪严重不足。

潮位超定量系列选样原则及频率分析

针对年最大值序列(AMS)用于潮位频率分析存在样本数量少且大量数据信息弃用的问题,采用超定量序列(PDS)开展潮位频率分析,从成因角度分析提出了潮位独立性分组选样原则,以瓯江温州站潮位为例,基于PDS样本,采用广义Pareto分布进行高潮位水文频率分析。结果表明,该方法与基于AMS的P-Ⅲ分布频率分析结果相近,5~200年一遇高潮位设计值差值在5%以内,同时PDS保留的潮位数据信息较AMS更充沛,高潮位重现期计算结果数理统计基础更优,可为沿海地区高潮位频率分析计算及论证提供参考。

基于自动分潮优化技术的辽东地区感潮河段河口区潮汐规律模拟研究

结合自动分潮优化技术对辽宁东部某感潮河段河口区的潮汐进行模拟。模拟分析结果表明:自动分潮优化技术可实现潮位数据的自动分潮优化,相比于国内发行的潮汐表提高5%~8%;对高低潮资料采用埃尔米特插值法,既考虑插值基点的高低潮位,又考虑高低潮一阶导数为0,潮位调和分析精度得到明显改善;采用潮位校正后的河口区潮位预报精度相比于校正前得到显著提高,各潮位站小于+10^+30cm合格率平均提高18.9%和7.2%。

Tidal analysis in the venturi-shaped area between Zhenhai and Shenjiamen in the East China Sea

In order to better understand the general tidal features in the venturi-shaped area between Zhenhai and Shenjiamen in the northern coastal region of Zhejiang Province in the East China Sea, the tidal data were obtained from both the three permanent tide stations of Zhenhai, Dinghai and Shenjiamen, and four temporary tide stations of Mamu, Chuanshan, Guoju and Liuheng, along with the current speed being observed at Luotou Waterway. Results from harmonic analysis show that: (1) The area was dominated by shallow water tides with irregular semi-diurnal features, and the smallest tidal range occurred in the area near a crossing line between Zhenhai and Dinghai stations, indicating that a tidal node existed in the southern Hangzhou Bay; (2) Formulae, HS2/HM2 >0.4 and gM2-(gK1+gO1)=270° (where H and g are harmonic constants), could be used as judging criteria for high and low tidal level diurnal inequalities; (3) The duration difference between ebb and flood tides could be roughly assessed by the ratio of HM4 vs. HM2; and the larger the ratio is, the bigger the duration difference is. At the same time, the duration period could be assessed by 2gM2-gM4, the epoch difference between M2 and M4 tidal constituents. If 2gM2-gM4 <180°, then the ebb duration is longer than the flood duration; if 180°< 2gM2-gM4 <360°, the result is reversed; (4) Taking Dinghai station as a center point, the highest tidal levels and the average high tidal levels, as well as the average tidal ranges at all stations became higher and larger both southeastwards and northwestwards, while the lowest tidal levels and the average low tidal levels appeared to be lower both southeastwards and northwestwards; and (5) The tidal patterns were not all in line with the tidal current patterns. As a conclusion, the smallest tidal range occurred in the narrow part of the venturi-shaped area. Along the both sides of the area, the highest tidal level and tidal range became higher and larger, while the lowest tidal level became lower with the increase of the distance from the narrow throat area. This is somehow different from the theory that the tidal level increases gradually when it moves towards the top narrow area of a V-shaped bay or estuary.

Tidal Analysis of High and Low Water Data

The harmonic analysis method based on high and low water levels is discussed in this paper. In order to make full use of the information of high and low water observations (the time derivative of water level at the observation time is zero), the weight coefficient, w, is introduced to control the importance of the part related to this information in the error formula. The major diurnal constituents, O 1 and K 1, and semi diurnal constituents, N 2, M 2 and S 2 are selected directly from the monthly data analysis, and some other important constituents, P 1, ν 2 and K 2, are included as the inferred constituents. The obtained harmonic constants of the major constituents are very close to those obtained from the analysis of hourly data, and this shows that high and low water data can be used to extract tidal constants with high accuracy. The analysis result also shows that the inference and the weighting coefficient are important in the high and low water data analysis, and it is suggested that w ≥1 should be taken in monthly high and low water data analysis. This analysis method can be used directly to analyze altimetric data with w =0.

Tidal Response Characteristics of the Well Water Level in the Sichuan-Yunnan Region

In this paper,the long time series data of the well water-level data of 12 wells in the Sichuan and Yunnan area is analyzed by the Baytap-G tidal analysis software,and well water level tidal response characteristic parameters( amplitude ratio and phase change)are extracted. We analyzed the features of the shape and stage change,and characteristic parameters of the tidal response of well water level before and after the earthquakes,which can provide a new method and approach to analyzing the response relationships between well water level and earth tide and barometric pressure. The results show that Luguhu Well and 9 other wells are affected by earth tides,and their well water level amplitude ratios and phases are relatively stable; the Nanxi Well and Dayao Well water level changes are affected by the barometric pressure combined with tide force,and their well water level amplitude ratios and phases are more discrete. The water level amplitude ratios and phases of Jiangyou Well,Luguhu Well and Dongchuan Well are significant to large earthquakes,and the relationship between seismic energy density and water level amplitude ratios and phases of M_2 wave of the three wells are presented.

Carbon and nitrogen isotopes analysis and sources of organic matter in the upper reaches of the Chaobai River near Beijing,China

The carbon and nitrogen isotopes in the surface sediments,plants,and soil in the upper reaches of the Chaobai River have been researched.The results showed 27.75‰-21.58‰ and 1.32‰-6.74‰ for carbon and nitrogen isotopic ratios in the surface sediments,respectively.The sources of sedimentary organic matter in this area are soil organic matter,aquatic vascular plants,and riverine plankton,respectively,and a significant contributor to sediment in the Chaohe River,the Baihe River,and the Miyun Reservoir areas is soil organic matter.Furthermore,part of sedimentary organic matter in the Miyun Reservoir is attributed to the input from the Chaohe River and the Baihe River,the other is from C4 vegetation growing around individual point stations at the Miyun Reservoir.Compared with the situation in Hebei Province,the contribution of soil organic matter decreased significantly and river plankton and aquatic vascular plants increased significantly in Beijing municipal areas.This study reveals that the source of organic matter has a close relationship with the soil erosion.