Mathematical model of wave transformation over radial sand ridge field on continental shelf of South Yellow Sea

According to a deformed mild-slope equation derived by Guang-wen Hong and an enhanced numerical method,a wave refraction-diffraction nonlinear mathematical model that takes tidal level change and the high-order bathymetry factor into account has been developed.The deformed mild-slope equation is used to eliminate the restriction of wave length on calculation steps.Using the hard disk to record data during the calculation process,the enhanced numerical method can save computer memory space to a certain extent,so that a large-scale sea area can be calculated with high-resolution grids.This model was applied to wave field integral calculation over a radial sand ridge field in the South Yellow Sea.The results demonstrate some features of the wave field:(1)the wave-height contour lines are arc-shaped near the shore;(2)waves break many times when they propagate toward the shore;(3)wave field characteristics on the northern and southern sides of Huangshayang are different;and(4)the characteristics of wave distribution match the terrain features.The application of this model in the region of the radial sand ridge field suggests that it is a feasible way to analyze wave refraction-diffraction effects under natural sea conditions.     

河型成因研究及其应用

大水淤滩刷槽、小水淤槽、河性对河型就在这对相互矛盾过程的相互交替、相互抵消、相互消长中形成。演化。前者导向好河，后者导向坏河。两者的强弱对比，就是河性河型差异的总根据。可用来水来沙关系的ｍ值来表达这种对比，ｍ〉２．５的将形成单股窄深蠕动性河型，ｍ〈２．５的则形成多宽浅游荡河型。改变来水来沙关系的ｍ值，大水淤滩刷槽、小水淤槽过程的强弱地经也就改变，河性河型逐步改变。这就是调水调沙、改造河性的真谛。将     

黄河河口生态需水分析

黄河入海水量及其流量变化过程对保障其河口三角洲生态健康具有十分重要的作用。本文分析了黄河三角洲生态系统的结构、组成及其功能,认为该生态系统关键期为5—9月。分析了黄河渔洼以下三角洲生态系统中的陆域湿地、河流湿地以及近海水域等重要生态单元生境修复与黄河径流条件的关系,重点分析了鸟类生境、河道内鱼类生境和近海水生生物繁衍生境的生态需水,提出了它们对黄河入海水量及其流量过程的要求。在统筹考虑黄河天然径流条件、自然功能用水和社会功能用水的平衡、黄河水资源配置条件等因素后,进一步提出现阶段黄河向其三角洲生态系统提供的生态用水控制指标：5—6月繁殖关键期的适宜水量约22亿m3,相应的利津断面流量应不低于150m3/s,最好能达到250m3/s;7—10月应保障洪水量级不低于3500m3/s、平水期流量不低于200～300m3/s;11月—次年4月流量应不低于75m3/s,最好能达到120m3/s。     

基于床面形态的泥沙输移模式及其在黄河下游的应用

冲积河流系统中,水流在不规则床面上产生的漩涡对泥沙悬浮效率影响很大.基于漩涡流的运动特征及床面形态控制数m,本文研究了水流阻力与床面形态运动之间的关系.同时,在Bagnold泥沙悬浮效率(η_(sl))概念的基础上,提出了床沙质输沙能力公式,对其中的η_(sl)C_*进行了深入研究,建立的η_(sl)C_*与1/m的关系,能够反映床面形态由低能态到高能态区的发展过程.研究提出的输沙公式,经黄河下游调水调沙试验等实测资料验证表明,计算结果与实测值特别是相对平衡条件下的实测值吻合较好.在输沙能力公式研究中引入反映床面形态控制参数是一种新的尝试,该方法在研究中显示出较大的发展潜力.     

黄河下游堤防存在问题研究

分析了黄河下游防洪体系中存在的问题,如临河坑塘、临河堤跟河、近堤洼地、近堤渠道、近堤水井等。指出近堤坑塘极易造成堤基渗漏和管涌,临河堤跟河极易导致顺堤行洪和滚河险情,近堤水井极易形成透水通道。根据先近后远、先深后浅、先背河后临河、先重点后一般的原则,提出解决问题的编制标准。     

黄河下游漫滩洪水含沙量和级配变化研究

通过模型试验,研究了黄河下游夹河滩到高村断面河段漫滩洪水含沙量及颗粒级配的沿程变化规律。结果表明：（1）各种流量条件下,主槽含沙量沿程增大,但差别较大。（2）漫滩挟沙水流在滩区含沙量沿程衰减,在生产堤内及滩面衰减幅度较大,在二滩衰减幅度较小;同时,漫滩挟沙水流中的泥沙颗粒在落淤过程中有明显的分选作用。（3）二滩沿程含沙量衰减率与大河洪峰流量有关,流量越小,含沙量衰减越快。     

李白、崔颢《黄鹤楼》诗案考辨

分析了李白、崔颢《黄鹤楼》诗案本末,认为肯定诗案的观点缺乏有力的依据,质疑诗案的观点值得重视。提出否定诗案的5个视点及澄清诗案的4点意义。     

Monitoring water level and volume changes of lakes and reservoirs in the Yellow River Basin using ICESat-2 laser altimetry and Google Earth Engine

Monitoring the water level and volume changes of lakes and reservoirs is essential for deepening our understanding of the temporal and spatial dynamics of water resources in the Yellow River Basin, with a view to better utilizing and managing water resources. In recent years, there have been many studies on monitoring water level and volume changes in inland waters, but they were mainly focused on radar altimetry and the full waveform LiDAR ICESat, which was retired in 2010. Few studies based on the latest photon-counting LiDAR ICESat-2 have been reported. Compared with previous sensors, ICESat-2 has great advantages in footprint size, transmitting frequency, pulse number, etc, but its performance in monitoring water level and volume changes in inland waters has not been fully explored. Here we investigated the spatial distribution of water level and volume changes of 11 lakes and 8 reservoirs in the Yellow River Basin based on ICESat-2 and Google Earth Engine, and analyzed the factors affecting the measurement uncertainties. In-situ validation of lake level in Lake Qinghai indicates that the Root Mean Square Error (RMSE) of our result is only 7 cm after the reference coordinate system conversion. We found that the water level trend of the natural lake shows significant seasonal variations, while the water level trend of the reservoir shows a sharp rise and fall. In addition, precipitation plays a decisive role in the changes in natural lake levels and indirectly affects the artificial control of reservoirs’ water discharges. The uncertainty of water volume change monitoring is mainly affected by water level measurement uncertainty for lakes, while for reservoirs, that is affected by the combination of water level and area measurement uncertainties. The stability of lake level measurement increases with the increase in photon counts. The introduction of ICESat-2 ATL13 Significant Wave Height might lead larger standard deviation in water level measurement. According to the law of propagation of uncertainty, the uncertainty of the water volume change estimation by the combination of ICESat-2 and GEE is less than 9 %.     

南水北调中线穿黄隧洞关键技术问题研究

南水北调中线穿黄隧洞施工中存在着地质条件差、工程结构复杂等问题,因此施工难度很高。结合实际施工特点和技术研究应用,介绍了地连墙技术、盾构始发加固技术、盾构施工技术、内衬混凝土施工技术、隧洞防渗等几项关键技术。     

龙口水利枢纽工程规模论证

从目前电力系统的发展来看,不论是华北电网还是晋、蒙电网都存在着调峰能力不足的问题。为更好地利用黄河托龙段的水能资源,改善下游河道的水流条件,为地方经济建设提供清洁可靠的能源,建设龙口水利枢纽工程已经提到日程上来。龙口水利枢纽工程开发任务为发电、对万家寨电站进行反调节、兼有滞洪削峰等综合利用。根据电力系统的需求、泥沙淤积情况、动能经济指标和反调节等要求,综合考虑,选定正常蓄水位898m,装机容量420MW。龙口水利枢纽工程的建设符合国家关于调整能源结构,优先开发水电和加强基础设施建设,拉动经济增长的部署。