长江口邻域叶绿素a和初级生产力的分布

海水中的叶绿素a浓度是浮游植物现存量的重要指标,其分布反映出了水体中浮游植物的丰度及其变化规律.初级生产力反映了水域初级生产者通过光合作用生产有机碳的能力,是海洋生物链的第一个环节,是海洋生态系统研究的重要内容,也是海域生物资源评估的重要依据.河口及其邻近海域是人类活动较为频繁的海域,也是生物海洋学研究过程的重要区域.长江口是陆源物质输入东海的主要场所,径流把大量的悬浮泥沙和丰富的溶解营养盐带入海洋,造成了长江口邻近海域独特的生态环境特征,成为了诸多研究的焦点.     

黑河干流洪水预报模型研究

黑河干流上游区水文站点稀少,区间部分支流洪水过程无法控制,中游区河流沿程大量引水灌溉、取水口甚多用水量无法获得,使得以水量平衡原理为基础的洪水演算方法难以应用。针对上述情况,笔者应用系统水文模型理论并对其进行了改进。通过引入系统存贮变量,建立了一个新的黑河干流洪水预报模型-河道洪水演算模型。经1996年,1998年两次特大洪水试报检验,结果表明该模型的预报精度较高,对黑河干流防洪减灾、水利工程科学管理以及水资源优化配置具有重要的作用。     

塔克拉玛干沙漠和田河西侧胡杨沙堆的形态特征及空间分布格局

胡杨沙堆是风沙流遇到胡杨干扰,沙物质堆积而形成的一种风积地貌类型。在风沙地貌领域,对胡杨沙堆的研究几乎空白。和田河西侧、麻扎塔格山以南的塔克拉玛干沙漠中分布有大量胡杨沙堆。基于野外RTK测量数据,利用GIS和统计手段,对胡杨沙堆进行信息提取与统计,定量分析了和田河西侧10个样方内胡杨沙堆的形态参数及沙堆空间分布格局。结果表明:1)沙堆形态不规则,形态参数空间差异显著,南北向形态参数均值变化较东西向稳定; 2)样方内沙堆形态参数间有良好的相关性,大部分沙堆处于发育阶段; 3)沙堆分布较稀疏,自西向东沙堆分布密度逐渐增大,从南到北为减小-增大-减小的变化趋势,总体上南部密度大于北部,东部密度大于西部; 4)10个样方沙堆与特定距离的随机分布差异性较小,整体上为离散分布,但东部较西部、北部较南部有小部分区域聚集分布。     

Water discharge variability of Changjiang （Yangtze） and Huanghe （Yellow） Rivers and its response to climatic changes

Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Lijin station in the Huanghe （Yellow） River and at the Datong station in the Changjiang （Yangtze） River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis （EMD- MESA） method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.     

MORPHOLOGICAL DEVELOPMENT OF ANATURE-LIKE BANK PROTECTION

1 INTRODUCTIONFor the pmpose of river restoration of the river Isar in the city area of Munich several inveshgationswere cAned out at the InshtUte for Hydrosciences, German Armed Forces University Munich. The calculation ofwater level for the differnt planned variants were realized by a 2d mathematical model. Although thesesimulahons were a very helpfol basis for fuIther planing, a physical model was constrUcted in order toinvestigate detalled problems.The main interest was focussed …     

黄河三角洲YDZ1孔沉积环境分析

对黄河三角洲五号桩附近YDZ1孔沉积物进行粒度分析,结果表明沉积物粒度参数在垂向分布序列上表现出一定的规律性.运用粒级-标准偏差法得到YDZ1孔沉积物的环境敏感粒度粒级范围为2.75～3.75φ.根据粒度参数变化的规律性和环境敏感粒度组分平均粒径的垂向分布特征,结合沉积物样品分样描述和ASM14C测年数据,分析了末次盛冰期以来黄河三角洲地区沉积环境的变化过程.     

长江流域大洪水有序网络结构及其预测研究

根据1827年以来的统计资料进行分析,长江流域大洪水展示出极为显著的有序性.运用翁文波信息预测理论,构建长江大洪水二维平面和三维立体信息有序网络结构并进行综合分析和预测,结果表明：2014、2020、2030、2036、2051与2058年前后的汛期,长江流域将有可能发生大洪水.     

Variations of Terrestrial Water Storage in the Yangtze River Basin under Climate Change Scenarios

In this study, the water balance-based Precipitation-Evapotranspiration-Runoff (PER) method combined with the land surface model Variable Infiltration Capacity (VIC) was used to estimate the spatiotemporal variations of terrestrial water storage (TWS) for two periods, 1982–2005 (baseline) and 2071–2100, under future climate scenarios A2 and B2 in the Yangtze River basin. The results show that the estimated TWS during the baseline period and under the two future climate scenarios have similar seasonal amplitudes of 60–70 mm. The higher values of TWS appear in June during the baseline period and under the B2 scenario, whereas the TWS under A2 shows two peaks in response to the related precipitation pattern. It also shows that the TWS is recharged from February to June during the baseline period, but it is replenished from March to June under the A2 and B2 scenarios. An analysis of the standard derivation of seasonal and interannual TWS time series under the three scenarios demonstrates that the seasonal TWS of the southeastern part of the Yangtze River basin varies remarkably and that the southeastern and central parts of the basin have higher variations in interannual TWS. With respect to the first mode of the Empirical Orthogonal Function (EOF), the inverse-phase change in seasonal TWS mainly appears across the Guizhou-Sichuan-Shaanxi belt, and the entire basin generally represents a synchronous change in interannual TWS. As a whole, the TWS under A2 presents a larger seasonal variation whereas that under B2 displays a greater interannual variation. These results imply that climate change could trigger severe disasters in the southeastern and central parts of the basin.     

1990年以来黄河第一湾齐哈玛河段砾质网状河的演变特征

黄河第一湾的网状河型因其砾石质的河床质而与砂床质网状河明显不同,但是其具体的冲淤特性、河道与河间地的稳定性等是否与砂质网状河具有相似之处,尚待揭示。以齐哈玛乡主河道长约为12 km的砾石质网状河段为研究对象,利用1990年、2001年、2013年和2016年共4期Landsat遥感影像数据和2011年与2013年两期Google Earth高分辨率图像数据,结合野外采样观测分析其1990-2016年间的平面形态变化与沉积特征。结果表明：砾石质网状河整体具有很高的稳定性,众多分支河道与河间地无明显冲淤现象。网状带面积仅增加2.43%,陆地与水体面积比例接近1∶1;网状带部分小型河间湿地及河间岛屿呈现碎片化现象,导致河间湿地个数逐渐增加,最大增加率为62.16%。河道主流线长期左右迁移交替变化,且变化率相对稳定,受主流线迁移的影响,主河道内部河间岛屿形态变化较大,其河岸变化率为5 m/a。网状河众多支河道非常稳定,平均河宽变化率仅为1 m/a左右。河岸沉积物以细砂或粉砂为主,黏土含量较高,粒度分布曲线呈现多峰,这与砂质网状河流河岸以泥质沉积物为主略有不同,但河岸及河间湿地茂密的植被保护了众多分支河道免受侵蚀、维持了河道的稳定性,这也是砾石质网状河流体系具有高稳定性的重要原因。     

盐城滨海港区防波堤建设对水下地形的影响研究

利用双频测深仪和声学多普勒流速仪对滨海港区附近海域进行了区域测深和定点全潮水文观测,通过与以往调查研究资料的对比,分析了防波堤建成前后海底冲淤变化特征。研究结果表明:近20年以来水下岸坡为侵蚀最剧烈的区域,海底平原则处于相对稳定状态;受自然侵蚀的影响,水下岸坡继续向岸内移,目前最强侵蚀区已内移至–8~–12 m水深的水下岸坡;近年来自然侵蚀明显减弱,年均侵蚀速率约为前10年的1/4;受防波堤挡流效应的影响,口门南侧已由往复流转变为旋转流;目前已出现三大淤积区域,其中以口门处淤积最严重,最大淤积厚达3.5 m,已造成口门处水深不足–10 m;防波堤对周边海域直接影响范围约13.4 km~2,最远可达废黄河口。分析认为,防波堤建设是引起港区海底冲淤格局发生变化的主因。该研究为防波堤的后续维护及滨海港区30万t级航道工程论证提供了基础资料。