Geochemical genesis of geothermal waters from the Longling hydrothermal area, Yunnan, Southwestern China

Longling is characterized by a wide distribution of hydrothermal areas, among which the Banglazhang hydrothermal system is the most geothermally active. Banglazhang is marked by intensive hydrothermal activities including hot springs, geysers, fumaroles and hydrothermal explosions. The geothermal waters from the Longling region are mainly HCO3-Na type with low but comparable SO4 and Cl concentrations. Calculations based on a variety of chemical geothermometers and a K-Ca geobarometer indicate that the Banglazhang hydrothermal system has much higher subsurface temperature and CO2 pressure compared to the other systems such as Daheba, Dazhulin and Huangcaoba. However, geothermal water samples collected from all these alternative hydrothermal areas are either partially equilibrated with reservoir minerals or are immature. The silica-enthalpy relationships of Banglazhang geothermal waters indicate the presence of a deep geothermal fluid with an enthalpy value and silica concentration of 945 J/g（up to around 220 °C） and 339 mg/L. Our work indicates the Banglazhang area is a promising source in terms of long-term utilization of hydrothermal resources.

CO2 Pressure Shift and Broadening of Water Lines Near 790 nm

Carbon dioxide pressure-broadened ro-vibrational transitions belonging to thev^2＋3v^3 band of H2160 have been measured with a sensitive cavity ring-down spectrometer. Water vapor of relatively low pressures （〈0.5 Torr） was used to limit the self-collisions among water molecules. After the calibration using the precise atomic transitions of Rb and a thermo- stabilized Fabry-Perot interferometer, 10^-5 cm^-1 frequency accuracy has been achieved. Line parameters are derived from least-squares fitting of the spectra using the ＂soft＂ collision model. The retrieved line parameters can be applied in the study of water absorption in the CO2-rich atmospheres of planets like Venus and Mars.

Moisture Analysis of a Squall Line Case Based on Precipitable Water Vapor Data from a Ground-Based GPS Network in the Yangtze River Delta

A squall line swept eastward across the area of the Yangtze River Delta and produced gusty winds and heavy rain from the afternoon to the evening of 24 August 2002. In this papers the roles of moisture in the genesis and development of the squall line were studied. Based on the precipitable water vapor （PWV） data from a ground-based GPS network over the Yangtze River Delta in China, plus data from a Pennsylvania State University/National Atmospheric Center （PSU/NCAR） mesoscale model （MM5） simulation, initialized by three-dimensional variational （3D-VAR） assimilation of the PWV data, some interesting features are revealed. During the 12 hours prior to the squall line arriving in the Shanghai area, a significant increase in PWV indicates a favorable moist environment for a squall line to develop. The vertical profile of the moisture illustrates that it mainly increased in the middle levels of the troposphere, and not at the surface. Temporal variation in PWV is a better precursor for squall line development than other surface meteorological parameters. The characteristics of the horizontal distribution of PWV not only indicated a favorable moist environment, but also evolved a cyclonic wind field for a squall line genesis and development. The ＂＋2 mm＂ contours of the three-hourly PWV variation can be used successfully to predict the location of the squall line two hours later.

Acoustic multipath structure in direct zone of deep water and bearing estimation of tow ship noise of towed line array

In the towed line array sonar system,the tow ship noise is the main factor that affects the sonar performance.Conventional noise cancelling methods assume that the noise is towards the endfire direction of the array.An acoustic experiment employing a towed line array is conducted in the western Pacific Ocean,and a strange bearing-splitting phenomenon of the tow ship noise is observed in the array.The tow ship noise is split into multiple noise signals whose bearings are distributed between 10°and 90°deviating from the endfire direction.The multiple interferences increase the difficulty in recognizing the target for the sonar operator and noise cancellation.Therefore,making the mechanism clear and putting forward the tow ship noise splitting bearing estimation method are imperative.In this paper,the acoustic multi-path structure of the tow ship in deep water is analyzed.Then it is pointed out that the bearing-splitting phenomenon is caused by the main lobe of direct rays and bottom-reflected rays,as well as several side lobes of direct rays.Meanwhile,the indistinguishability between the elevation angle and the bearing angle due to the axial symmetry of a strict horizontal line array causes the bearing to deviate from the endfire direction.Based on the theory above,a method of estimating bearing of the tow ship noise in deep water is proposed.The theoretical analysis results accord with the experimental results,which helps to identify the target and provide correct initial bearing guidance for noise cancelation methods.

On-line Measurement of Water-Soluble Ions in Ambient Particles

Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography （RCFP-IC） was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO4^2-, NO3^-, NO2^-, Cl^- and F- is below 0.3μg m^-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring.

Determination of triazine herbicide residues in water samples by on-line sweeping concentration in micellar electrokinetic chromatography

A new method for the determination of atrazine, simazine and prometryn in water samples by on-line sweeping concentration technique in micellar electrokinetic chromatography （MEKC） was developed. Various parameters affecting sample enrichment and separation efficiency were systematically studied. Compared with the conventional MEKC method, up to 60-200-fold improvement in concentration sensitivity was achieved in terms of peak height by using this sweeping injection technique. The compound strychnine was used as the internal standard for the improvement of the experimental reproducibility. The limits of detection （S/ N = 3：1） for atrazine, simazine and prometryn were 9, 10 and 0.5 ng mL-1, respectively. This method has been successfully applied to the analysis of atrazine, simazine and prometryn in lake, steam and ground water.

DETERMINATION OF ANTIMONY IN WATER SAMPLES BY FLOW-INJECTION HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY WITH ON-LINE ION-EXCHANGE COLUMN PRECONCENTRATION

On-line ion-exchange separation and preconcentration were combined with flow-injection hydride generation atomic absorption spectrometry (HGAAS) to determine ultra-trace amounts of antimony in water samples. Antimony(Ⅲ) was preconcentrated on a micro-column packed with CPG-8Q chelating ion-exchanger using time-based sample loading and eluted by 4 mol l^(-1) HCl directly into the hydride generation AAS system. A detection limit (3σ) of 0.0015μg l^(-1) Sb(Ⅲ) was obtained on the basis of a 20 fold enrichment and with a sampling frequency of 60h^(-1). The precision was 1.0% r.s.d.(n=11) at the 0.5μg l^(-1) Sb(Ⅲ) level. Recoveries for the analysis of antimony in tap water, snow water and sea water samples were in the range 97-102%.

Adaptability and recovery capability of two maize inbred-line foundation genotypes, following treatment with progressive water-deficit stress and stress recovery

Two maize inbred lines, the foundation genotype Y478 and its derived line Z58, are widely used to breed novel maize cultivars in China, but little is known about which traits confer Z58 with superior drought tolerance and yield. In the present study, responses in growth traits, photosynthetic parameters, chlorophyll fluorescence and leaf micromorphological characteristics were evaluated in Y478 and Z58 subjected to water-deficit stress induced by PEG 6000. The derived line Z58 showed greater drought tolerance than Y478, which was associated with higher leaf relative water content (RWC), root efficiency, and strong growth recovery. Z58 showed a higher stomatal density and stomatal area under the non-stressed condition;in these traits, both genotypes showed a similar decreasing trend with increased severity of water-deficit stress. In addition, the stomatal size of Y478 declined significantly. These micromorphological differences between the two lines were consistent with changes in physiological parameters, which may contribute to the enhanced capability for growth recovery in Z58. A non-linear response of Fv/Fm to leaf RWC was observed, and Fv/Fm decreased rapidly with a further gradual decline of leaf RWC. The relationship between other chlorophyll fluorescence parameters (photochemical quenching and electron transport rate) and RWC is also discussed.

Feasibility of Transferring Drinking Water from the Senegal River in the East (Backel) to the West Center (Fatick) in Senegal

Every year, 24 billion m3 of fresh water are thrown into the sea by the Senegal River, while most of the country’s populations do not have permanent access to drinking water. Also, agricultural land, which extends as far as the eye can see, is only used during winter periods, thus slowing down the development of agriculture. It is in this context that this article studies the feasibility of transferring drinking water from the Senegal River in the east of the country to the center-west through a transfer canal to meet the drinking water needs of the populations. In addition, we intend to flood the fossil valleys from this canal and recharge the aquifers. The watershed resulting from the juxtaposition of the two watersheds which dominate central Senegal has a slightly descending profile from Bakel to Fatick. This promotes gravity flow of water over 542 km. This analysis is carried out by the Glabal Mapper software and SRTM1 images. We report that all water needs have been estimated at approximately 70 m3/s based on the ANDS census in 2023, the distribution of arable land and groundwater recharge areas in the country. The waters flowing in the canal have depths (draft) not reaching 4.6 m. These results are obtained by applying the Manning Strickler equation, on a channel with a straight cross-section in the shape of a trapezoid and lined with sand concrete. The canal thus designed will bring water to populations and arid zones in the central and central-western regions of the country where problems persist. However, it will be necessary to overcome a difference in altitude of 96 m over 30 km to raise the water from the river to the threshold of the canal in order to ensure the flow in the latter. We have retained two calculation variants (Canal + Pumping or Single Pumping) whose pumping stations will be powered by solar fields. Due to the heavy investments, the installations upstream of the canal will be modular over time. Consequently, the central canal project will be constructed in six (6) phases of ten (10) years.

Roughness evaluation in shotcrete-lined water tunnels with invert concrete based on cases from Nepal

Most of the existing roughness estimation methods for water tunnels are related to either unlined or concrete/steel-lined tunnels. With the improvement in shotcrete technology, advancement in tunneling equipment and cost and time effectiveness, future water tunnels built for hydropower projects will consist of rock support with the extensive use of shotcrete lining in combination with systematic bolting and concrete lining in the tunnel invert. However, very little research has been performed to find out tunnel surface roughness for shotcrete-lined tunnels with invert concrete, which is important in calculating overall head loss along the waterway system to achieve an optimum and economic hydropower plant design. Hence, the main aim of this article is to review prevailing methods available to calculate tunnel wall roughness, and to use existing methods of head loss calculation to back-calculate roughness of the shotcrete-lined tunnels with invert concrete by exploiting measured head loss and actual cross-sectional profiles of two headrace tunnels from Nepal. Furthermore, the article aims to establish a link between the Manning coefficient and the physical roughness of the shotcrete-lined tunnel with invert concrete and to establish a link between over-break thickness and physical roughness. Attempts are also made to find a correlation between over-break thickness and rock mass quality described by Q-system and discussions are conducted on the potential cost savings that can be made if concrete lining is replaced by shotcrete lining with invert concrete.

Research on Relationship between Recovery Ability after Drought Stress-rewatering and Water Use Efficiency of Winter Wheat Varieties

The study aims at exploring the possibility of using the recovery ability af- ter drought stress-rewatering at vegetative growth stage as the evaluating index in water use efficiency （WUE） of winter wheat varieties. ＇Jing 411 ＇, ＇Jinmai 47＇ and their 34 near isogenic lines （NILs） were used as test materials. Semi-automatic rainproof shelter and the percolating pools were used for simulating drought treat- ment. After suffering severe drought stress, winter wheat crops were rewatered at early jointing stage. The biomass accumulation after rewatering was determined as recovery ability index. In the meanwhile, plant height in the end of vegetative growth stage was measured, and WUE of varieties/lines was also determined. Thereafter, the differences in recovery ability, plant height and the population WUE, together with the correlation between recovery ability and population WUE were analyzed, respectively. The results showed that there were significant differences in recovery ability among some varieties/lines. The recovery ability was affected by both geno- type and environment, and the interaction existed in these two factors. Significant differences existed in plant height and population WUE among the 34 NILs along with their parents. There was a significantly positive correlation between recovery ability and plant height of varieties/lines. Recovery ability and plant height were very significantly and positively correlated with population yield WUE respectively. The re- sults indicated that recovery ability after drought stress-rewatering could be used as an evaluating index of population WUE under drought condition.

Hydrochemical insights on the signatures and genesis of water resources in a high-altitude city on the Qinghai-Xizang Plateau, South-west China

Water resources have crucial implications for the steady development of the urban social economy.This study investigated the hydrochemical signatures and genesis of water resources in the urban area of Lhasa City(UALC).To this end,several analyses,such as ion ratio analysis and correlation analysis,were performed by comprehensively applying mathematical statistics and integrated hydrochemical methods.The results show relatively low concentrations of major ions in the groundwater and surface water(GSW)of the UALC.The primary anions and cations are HCO3-and Ca2+,reflecting the HCOg-Ca water type.Nevertheless,groundwater exhibits higher concentrations of key chemical components compared to surface water.GsW are weakly alkaline,with pH values of 7.78 and 7.61,respectively,and they have low salinity with average concentrations of total dissolved solids being 190.74 and 112.17 mg/L,respectively.Anthropogenic inputs have minimal influence on the hydrochemical features of GSw,whereas rock weathering is the dominant controlling factor.Furthermore,cation exchange.is a significant hydrogeochemical.process influencing their hydrochemical features.According to the isotope analysis(H and 180),the primary source of recharge for GSW is atmospheric precipitation,with some input from melted ice and snow.Moreover,GSW samples from the UALC show relatively similar 2H and 18O isotopic compositions,indicating the existence of a discernible hydraulic connection linking the two water sources.The research findings can serve as a valuable scientific reference and foundation for the sustainable development,effective utilization,and proper safeguarding of regional water resources in high-altitude areas.

Fractionation mechanism of stable isotope in evaporating water body

Under Rayleigh equilibrium condition, stable isotopic ratio in residual water increases with the decrease of the residual water proportion f exponentially, and the fractionation rate of stable isotopes is inversely proportional to temperature. However, under kinetic evaporation condition, the fi＇actionation of stable isotopes is not only related to the phase temperature but also influenced by the atmospheric humidity and the mass exchange between liquid and vapor phases. The ratio 6 in residual water will not change with f after undergoing evaporation of a long time for great relative humidity. The rate that the evaporating water body reaches isotopic steady state is mainly dependent on the relative humidity in atmosphere. The analysis shows that the actual mean linear variety rates, about -30.0, of the δ^18O in residual water versus the residual water proportion at Nagqu and Amdo stations are consistent with the simulated process under temperature of 20℃ and relative humidity of 50%. The distillation line simulated under Rayleigh equilibrium condition is analogous to the global meteoric water line （MWL） as the temperature is about 20℃. Under non-equilibrium condition, the slope and constant values of distillation line are directly proportional to temperature and relative humidity. According to the basic data, the simulated distillation line is very consistent with the actual distillation line of Qinghai Lake.

Environmental Isotopic Characterization of Groundwater and Surface Water in Northeast Missan Province,South Iraq

The present work studies the environmental isotopes assess groundwater characteristics of the different parts of the main aquifer in the northeast Missan Province in south of Iraq. Water samples of groundwater and surface water were collected for two dry and wet seasons during the water year of 2011-2012. The study shows that most of the groundwater in the aquifer falls above the global meteoric water line, and all the samples fall below the Mediterranean meteoric water line, indicating that these samples are a mixture of two water types. The tritium content of these samples supports this conclusion. The overall conclusion of this study indicates that there are two sources of groundwater recharge in the studied area： the ephemeral streams （Teeb and Dewerge） and major precipitation sources. According to the tritium levels at or below one tritium unit （TU） obtained from the water, supply wells are highly confined or ＂not vulnerable＂. Overall, the 3^H results imply that recent recharge has taken place during the last four to five decades. In the recharge area, the high tritium content in the southern part of the Teeb area suggests that the recharge originates from rapid infiltration of surface runoff. Therefore, the groundwater resources in the study area should be protected from contamination, because it will influence the aquifer in a relatively short period of time if any contamination enters the recharge areas of the aquifer.

Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh

In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M2 along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square error values.

3D Finite Element Analysis of TBM Water Diversion Tunnel Segment Coupled with Seepage Field

In most studies of tunnel boring machine(TBM)tunnelling, the groundwater pressure was not considered, or was simplified and exerted on the boundary of lining structure. Meanwhile, the leakage, which mainly occurs in the segment joints, was often ignored in the relevant studies of TBM tunnelling. Additionally, the geological models in these studies were simplified to different extents, and mostly were simplified as homogenous bodies. Considering the deficiencies above, a 3D refined model of the surrounding rock of a tunnel is firstly established using NURBS-TIN-BRe P hybrid data structure in this paper. Then the seepage field of the surrounding rock considering the leakage in the segment joints is simulated. Finally, the stability of TBM water diversion tunnel is studied coupled with the seepage simulation, to analyze the stress-strain conditions, the axial force and the bending moment of tunnel segment considering the leakage in the segment joints. The results illustrate that the maximum radial displacement, the minimum principal stress, the maximum principal stress and the axial force of segment lining considering the seepage effect are all larger than those disregarding the seepage effect.

Investigation of the Leaching Behavior of Mortar Pipe Lining in Drinking Water

The leaching behavior of three types of mortars was investigated using a self-design device which could simulate the field conditions of pipe lining. The results by ICP and ESEM measurement show that the developed slag cement mortar is suitable for the lining of cast iron pipe that is used for delivering drinking water.

Critical State Sedimentation Line of Soft Marine Clays

The compression behavior responsible for unity sensitivity is very valuable in quantitative assessment of the effects of soil structure on the compression behavior of soft marine sediments. However, the quantitative assessment of such effects is not possible because of unavailability of the formula for the compression curve of marine sediments responsible for unit sensitivity. In this study, the relationship between the remolded state and the conventional critical state line is presented in the deviator stress versus mean effective stress plot. The analysis indicates that the remolded state is on the conventional critical state line obtained at a relatively small strain. Thus, a unique critical state sedimentation line for marine sediments of unit sensitivity is proposed. The comparison between the critical state sedimentation line proposed in this study and the existing normalized consolidation curves obtained from conventional oedometer tests on remolded soils or reconstituted soils explains well the

Geological conditions and key rock mechanics issues in the Western Route of South-to-North Water Transfer Project

In terms of special geological conditions of the Western Route of South-to-North Water Transfer Project, the classification method for surrounding rocks is discussed by combining with the construction method of tunnel boring machine （TBM）. The classification standard of surrounding rocks is put forward on the basis of physical simulations and engineering practices. Damage, deformation and evolution of surrounding rocks induced by TBM excavation are discussed. Meanwhile, the long-term deformation mechanisms and stability of surrounding rocks are also studied. On this basis, a three-dimensional constitutive model for interbedded sandstone slate and a fiat shell-joint element-foundation system for calculating internal forces of segment lining are established. The deformation features of surrounding rocks of deep and steep interbedded sandstone slate and their influences on internal forces of segment lining are presented. Finally, the design methods of segment lining constructed in deep and steep flysch are proposed.

Fiber optic sensing and performance evaluation of a water conveyance tunnel with composite linings under super-high internal pressures

For long-distance water conveyance shield tunnels in operation,the high internal water pressure may cause excessive deformation of composite linings,affecting their structural integrity and serviceability.However,the deformation and failure characteristics of lining structures under internal water pressure are not well investigated in the literature,particularly for three-layer composite linings.This study presents an in situ experimental investigation on the response of two types of composite linings(i.e.separated and combined lining structures)subjected to internal pressures,in which a fiber optic nerve system(FONS)equipped with distributed strain and displacement sensing nerves was employed to monitor the performance of the two composite linings during testing.The experimental results clearly show that the damage of the tunnel lining under different internal pressures was mainly located in the self-compaction concrete layer.The separated lining structure responded more aggressively to the variations in internal pressures than the combined one.Moreover,two evaluation indices,i.e.radial displacement and effective stiffness coefficient,are proposed for describing the changes in the structural bearing performance.The effective stiffness coefficients of the two types of lining structures were reduced by 39.4%and 29.5%,respectively.Considering the convenience of field monitoring,it is suggested that the average strains at different layers can be used as characteristic parameters for estimating the health conditions of lining structures in service.The analysis results provide a practical reference for the design and health evaluation of water conveyance shield tunnels with composite linings.