Impact of the eastern water diversion from the south to the north project on the saltwater intrusion in the Changjiang Estuary in China

The south to the north project(WDP) on the saltwater intrusion in the Changjiang Estuary is studied by the improved three-dimensional(3D) numerical model.The net unit width flux in the Changjiang Estuary as well as the sectional salt flux is calculated in the North Branch(NB),the South Branch(SB),the North Channel(NC),the South Channel(SC),the North Passage(NP) and the South Passage(SP),respectively.The net seaward water flux in the SB is reduced,and the net water flux spilling over from the NB to the SB is enhanced after the eastern WDP.Under the mean river discharge condition in the dry season,the net salt flux spilling over from the NB to the SB is increased by 2.09 t/s and 0.52 t/s during the spring and neap tides,respectively,due to the eastern WDP.The saltwater intrusion in the Changjiang Estuary is enhanced by the eastern WDP.Compared with that during the spring tide,the net water diversion ratio during the neap tide in the NC is smaller,and thus the enhancement of the saltwater intrusion by the eastern WDP is smaller in the NC,and larger in the NP and the SP.The tidally averaged surface salinity at the water intakes of the Dongfengxisha Reservoir,the Chenhang Reservoir and the Qingcaosha Reservoir rises both during the spring and neap tides.     

б-sharpen immersed boundary method(б-SIBM)—New method for solving the horizontal pressure-gradient force(PGF) problem of б-coordinate

Althoughб-coordinate is one of the most popular methods used in marine and estuarine modeling,it has long suffered from the so-called"steep boundary problem",namely,the PGF problem.In this paper,a new method called the"б-sharpen immersed boundary method"(б-SIBM)is put forward.In this method,the virtual flat bottom boundary is creatively introduced in regions with the steep boundary and is taken as the boundary of numerical domain.By this,бHбx of numerical domain changes to be a controllable value and the steep bottom problem is then transformed to the non-conforming boundary problem,which is,in turn,solved by the SIBM.The accuracy and efficiency of theб-sharpen immersed boundary method(б-SIBM)has been showed by both comparative theoretical analysis and classical numerical tests.First,it is shown that theб-SIBM is more effective than the z-level method,in thatб-SIBM needs special treatment only in the steep section,but the z-level method needs the special treatment in each grid note.Second,it is superior to theб-method in that it is not restricted by the density distribution.This paper revisits the classical seamount numerical test used in numerous studies to prove the sigma errors of the pressure gradient force(PGFE)and their long-term effects on circulation.It can be seen that,as for the maximum erroneous velocity and kinetic energy,the value ofб-SIBM is much less than that of the z-level method and the traditionalб-method.sharpen immersed boundary method(SIBM),immersed boundary method(IBM),direct forcing method,б-coordinate,     

Research on precise trigonometric leveling in place of first order leveling

IntroductionWiththe extensive applications of the total sta-tioninstrument ,the electronic distance measure-ments for trigonometric leveling (belowas trigo-nometric leveling) has been getting more andmore application in surveying and mapping withits advantages such as fleetness ,si mplicity andconvenience and economy etc . And replacingthird or fourth order level surveying with trigo-nometric leveling has beenincludedinthe criteri-on and used for production,obtaining evident e-conomic effect .…     

Comparative Study and Spatial-Temporal Distribution of Regolith and Rock Geochemical Data from Xingmeng - North China

<正>1 Introduction Geochemical mapping at national and continental scales continues to present challenges worldwide due to variations in geologic and geotectonic units.Use of the proper sampling media can provide rich information on     

Profiles and Source Apportionment of Nonmethane Volatile Organic Compounds in Winter and Summer in Xi’an,China, based on the Hybrid Environmental Receptor Model

Summer and winter campaigns for the chemical compositions and sources of nonmethane hydrocarbons(NMHCs)and oxygenated volatile organic compounds(OVOCs)were conducted in Xi’an.Data from 57 photochemical assessment monitoring stations for NMHCs and 20 OVOC species were analyzed.Significant seasonal differences were noted for total VOC(TVOC,NMHCs and OVOCs)concentrations and compositions.The campaign-average TVOC concentrations in winter(85.3±60.6 ppbv)were almost twice those in summer(47.2±31.6 ppbv).Alkanes and OVOCs were the most abundant category in winter and summer,respectively.NMHCs,but not OVOCs,had significantly higher levels on weekends than on weekdays.Total ozone formation potential was higher in summer than in winter(by 50%)because of the high concentrations of alkenes(particularly isoprene),high temperature,and high solar radiation levels in summer.The Hybrid Environmental Receptor Model(HERM)was used to conduct source apportionment for atmospheric TVOCs in winter and summer,with excellent accuracy.HERM demonstrated its suitability in a situation where only partial source profile data were available.The HERM results indicated significantly different seasonal source contributions to TVOCs in Xi’an.In particular,coal and biomass burning had contributions greater than half in winter(53.4%),whereas traffic sources were prevalent in summer(53.1%).This study’s results highlight the need for targeted and adjustable VOC control measures that account for seasonal differences in Xi’an;such measures should target not only the severe problem with VOC pollution but also the problem of consequent secondary pollution(e.g.,from ozone and secondary organic aerosols).     

Analysis of Ship Motion in An Ice Ridge Field Based on Empirical Approach

The estimation of ship speed in ice ridge fields is important for both route planning and prediction of emergency response time. An analytical method for estimating ship motion in first-year ice ridge is developed based on ice resistance models and ship motion equations, in which the effect of ship speed on ridge resistance is taken into account. Two model tests in level ice and one model test in ice ridge for an icebreaking multipurpose vessel are used to validate and benchmark the presented me...     

Preliminary study on the dissolved oxygen distributions and the influential factors in the Daliao River estuary and its adjacent areas

Dissolved oxygen (DO) concentrations were surveyed in the Daliao River Estuary in autumn to investigate the temporal and spatial trends of DO distributions, The results indicate that DO is weakly stratified in the Yingkou section of the Daliao River Estuary, and remains constant vertically in the areas near and out of the entrance. Horizontally, both instantaneous and continuous observations show that the Yingkou section of the Daliao River Estuary is affected by hypoxic conditions; while no conditions of low DO have been observed in the areas near and out of the entrance.DO-salinity correlations exhibit different controlling factors of DO distributions in different sections of the Daliao River Estuary. At the upstream part of the Yingkou section of the Daliao River (A1-A4), oxygen demanding materials and the associated biochemical processes are the main factor controlling the DO distribution, but in the lower part of the Yingkou section and the area near and out of the entrance (A5-A15), tidal advections are more influential for DO distributions.