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Huang Y.,National University of Singapore | Huang Y.,Shenzhen Water Resources Planning and Design Institute | Zhu W.,Shenzhen Water Resources Planning and Design Institute | Le M.,Shenzhen Water Resources Planning and Design Institute | Lu X.,National University of Singapore
Quaternary International | Year: 2012

Heavy metal contamination has great ecological risk for river ecosystems due to its environmental toxicity, abundance and persistence. The examination and study of sediment quality can reveal the pollutant variations, degradations, cycles and chronic effects of water pollution. In this study, surface (0-60 mm) river sediment samples were collected and heavy metals (Cr, Cd, Hg, As, Zn, Cu and Pb) were analyzed in order to understand the spatial and temporal variation of heavy metals and its potential ecological risk in the Shenzhen River during 1991-2006. Cr showed a significant increasing trend (. P < 0.05), while both As and Cd increased but not with statistical significance (. P = 0.10) over time. A slightly increasing trend was found for Hg and Zn, but Pb and Cu showed no trend over time. Risk index (RI) ranged from 194.8 to 1417.6 in sediment, indicating considerable ecological risk or very high ecological risk for the aquatic environment. Among the 7 heavy metals, Cd and Hg were the major contributing (83%) elements for RI. Concentrations of heavy metals in sediment also have significant variations on spatial scale, high in industrialized and urbanized areas (Buji catchment, Futian catchment and Paihong catchment). RI ranged from 540.2 to 2876.8 for the 18 plots, and Cd was the major contributing heavy element (55.1-99.1%). The sediments of Shenzhen River all showed considerable ecological risk or very high ecological risk in 2004. © 2011 Elsevier Ltd and INQUA.

Huang Y.,National University of Singapore | Huang Y.,Shenzhen Water Resources Planning and Design Institute | Lu X.,National University of Singapore | Chen K.,Shenzhen Water Resources Planning and Design Institute
Environmental Monitoring and Assessment | Year: 2013

We presented measurements of wet deposition of NH 4 + -N and NO 3 - -N from 1986 to 2006 in Shenzhen City, China. Over the past 20 years, NO 3 - -N concentration had significantly increased, but a reverse trend was found for NH 4 + -N. The main form of total inorganic nitrogen (TIN) was NH 4 + -N and the average NH 4 + -N/NO 3 - -N ratio was 1.57 in this area. The contribution of NO 3 - -N to TIN increased from 28-42% in the period of 1986-2000 to 50-63% during 2001-2006. The increased deposition flux of NO 3 - -N resulted in the increasing trend of TIN, although NH 4 + -N showed a decreasing trend over time. Average deposition flux of TIN during 1986-2006 was 13.24 kg/ha/year, with a minimum value of 6.03kg/ha/year in 1988 and a maximum value of 20.52 kg/ha/year in 1997. Wet deposition fluxes of N appeared to vary with season, 81% occurred in the warm season (from April to September). The wet deposition of TIN to the Shenzhen Reservoir reached 8,902 kg in 2006, which contributed 9.95% of the total nonpoint pollution to the reservoir and will be increased in the future. © 2012 Springer Science+Business Media B.V.

Tang Y.,Sun Yat Sen University | Xi S.,Sun Yat Sen University | Xi S.,Shenzhen Water Resources Planning and Design Institute | Chen X.,Sun Yat Sen University | Lian Y.,University of Illinois at Urbana - Champaign
Advances in Meteorology | Year: 2016

Coastal flood regimes have been irreversibly altered by both climate change and human activities. This paper aims to quantify the impacts of multiple factors on delta flood. The Pearl River Delta (PRD), with dense river network and population, is one of the most developed coastal areas in China. The recorded extreme water level (m.s.l.) in flood season has been heavily interfered with by varied income flood flow, sea-level rise, and dredged riverbeds. A methodology, composed of a numerical model and the index R, has been developed to quantify the impacts of these driving factors in the the PRD. Results show that the flood level varied 4.29%-53.49% from the change of fluvial discharge, 3.35%-38.73% from riverbed dredging, and 0.12%-16.81% from sea-level rise. The variation of flood flow apparently takes the most effect and sea-level rise the least. In particular, dense river network intensifies the impact of income flood change and sea-level rise. Findings from this study help understand the causes of the the PRD flood regimes and provide theoretical support for flood protection in the delta region. Copyright © 2016 Yihan Tang et al.

Zhimin Y.,Shenzhen Water Engineering Construction Management Center | Shenwei S.,Hohai University | Yang P.,Shenzhen Water Resources Planning and Design Institute | Zhijian J.,Shenzhen Water Resources Planning and Design Institute
Proceedings - 2015 6th International Conference on Intelligent Systems Design and Engineering Applications, ISDEA 2015 | Year: 2015

Based on limit equilibrium finite difference method, the stability of deep foundation pit of the guanlan storage pool was analyzed. Simulation analysis and research in the process of design and calculation are carried out and the safety factors are also calculated in different situations to anchor inclination, rock shoulder width and embedded depth. The results of numerical simulation show that the design of deep foundation pit with the end-suspended supporting system is reasonable. The increase in anchor inclination will lead to the first increase of safety factor then decrease, so the anchor inclination of about 20° is reasonable. The increase in rock shoulder width or embedded depth can control effectively stability and deformation of deep foundation pit. The safety factor of foundation pit would be increasing with the two factors increasing firstly. However, when the value exceeded a certain value, their influences on stability of foundation pit will tend to be insignificant. © 2015 IEEE.

Yang P.,Shenzhen Water Resources Planning and Design Institute | Zhilei H.,Hohai University | Zhende Z.,Hohai University | Zhijian J.,Shenzhen Water Resources Planning and Design Institute | Memetyusup S.,Hohai University
Proceedings - 7th International Conference on Intelligent Computation Technology and Automation, ICICTA 2014 | Year: 2015

The stress unloading of surrounding rock in the excavation of tunnel may cause instability and failure of rock mass. There is a kind of unloading confining pressure experiments designed by using an MTS815.04 electro hydraulic servo-controlled testing machine. That is experiment of increasing axial pressure while decreasing confining pressure. Then the deformation properties of marble under unloading condition are analyzed. The results show that when axial pressure increases while confining pressure decreases, the peak of axial strain decreases compared with loading experiment, and the deviatoric stress tends to be stable in the late unloading stage of high initial confining pressure while the fracture toughness reinforces. It also shows that the failure modes of samples exhibits a relatively strong brittleness in the low confining pressure but changes toward to toughness with increase of confining pressure. The failure characteristics changes from tensile to tension-shear and the destruction of samples in unloading experiment should be more strongly than that in loading experiment. With the initial confining pressure increasing in unloading experiment, the deformation parameters of marble is no longer constants and both of them take place the effect of damage degradation in a certain degree. The elastic modulus increases gradually but has an decrease of 50%-100% compared with triaxial experiment, on the contrary, the Poisson ratio decreases gradually but has an increase of 30%-80% compared with triaxial experiment. The unloading conditions of increasing axial pressure while decreasing confining pressure have a great effect on sample deformation and there is a quadratic nonlinear relationship between elastic modulus of surrounding rock and initial confining pressure. © 2014 IEEE.

Chen J.,Hohai University | Gao B.,Hohai University | Li T.,Shenzhen Water Resources Planning and Design Institute | He W.,Hohai University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2013

It is the first time to detect the leakage channel of the dam by slug test; for that the slug test is used to get the permeability coefficient of a point. Based on the Ling ao Reservoir project, the leakage channel of the dam is detected at the zone pile No. 0+250-295 after a series of slug tests. Using the method of temperature tracer method and detecting of electrical conductivity, it is found that the result is basically the same with the result gotten by slug test. After grouting to the zone of pile No. 0+275-295, there is an obvious effect through the reservoir water level and the flow rate of dam weir. So it demonstrates the correctness of the measuring result of slug test. There is great practical significance and broad application prospects for the application of slug test to detect the leakage passages and overhaul reinforcement of earth-rock dam and riverbank.

Liu D.,Tianjin University | Xuan P.,Tianjin University | Li S.,Purdue University | Huang P.,Shenzhen Water Resources Planning and Design Institute
Journal of Computing in Civil Engineering | Year: 2015

Schedules are fundamental parameters for decision making in the design phase of tunnel construction projects. Schedule estimates of tunnel construction projects are subject to major uncertainties caused by uncertain geologic conditions and risks. This research presents an adaptive cyclic operation network simulation (CYCLONE) simulation technique to predict the schedule of tunnel boring machine (TBM) tunneling and quantifies the impacts of geologic risks along a tunnel in the design phase. A geologic prediction model is integrated with expert judgments to evaluate the probabilistic geologic risks along the tunnel alignment. An adaptive CYCLONE simulation technique is developed to flexibly adjust the durations, arrangements, and modes of construction operations in response to the occurrences of geologic risks and changes of geologic conditions. The applicability of the proposed method was demonstrated by an illustrative case study - Jinping (JP) hydraulic tunnel project in southwest China. The simulation results indicate that this project has a high risk of delays caused by geologic hazards. The analysis of the simulation results reveals that the schedules of tunneling and the uncertainty in the schedules will be underestimated if geologic risks are not considered well in the simulation. The incorporation of geologic risks and the adaptability of the simulation model would lead to a more accurate and robust simulation. © 2014 American Society of Civil Engineers.

Both fresh and saline groundwater may be of some value to coastal communities. A comprehensive simulation-optimization model was developed to identify optimal solutions for managing both types of groundwater in coastal areas. The model may be used for conventional management problems of fresh groundwater development and of seawater intrusion control. In addition, the model can be used for problems of concurrent development of fresh and saline/brackish groundwater for beneficial uses. A set of hypothetical examples is given to demonstrate the applicability of the proposed model. In the protection of an over-exploiting freshwater pumping well, the saltwater pumping scheme was less efficient than the freshwater injection scheme. Although the former scheme may be more advantageous in some limited cases, the latter should be considered first as it retains more freshwater in the aquifer. The example of the concurrent development of fresh and brackish groundwater exhibited two different sets of optimal solutions: one with a large amount of freshwater and a small amount of brackish water with high salinity, and the other with a small amount of freshwater and a large amount of brackish water with low salinity. © 2015, Springer-Verlag Berlin Heidelberg.

Jiao J.J.,University of Hong Kong | Shi L.,University of Hong Kong | Shi L.,Shenzhen Water Resources Planning and Design Institute | Kuang X.,University of Hong Kong | And 3 more authors.
Hydrogeology Journal | Year: 2015

Offshore hydrogeology has been much less studied compared to onshore hydrogeology. The marine Quaternary system in Hong Kong (China) consists of interlayers of aquitards and aquifers and was part of the Pearl River Delta when the sea level was low before the Holocene. Core samples from six offshore boreholes were collected to measure the chloride concentration in the system by adding deionized water. A method was proposed to convert the sediment chloride into that of the original pore water. A one-dimensional sedimentation-transport model was developed to simulate the historical conservative transport of the reconstructed pore-water chloride. The model integrates present knowledge of stratigraphy and the historical evolution of the geological system. The chloride concentration profiles show that the chloride decreases from an average of 13,800 mg/L in the first marine unit to an average of 5,620 mg/L in the first aquifer. At the bottom of one borehole, the concentration is only 1,420 mg/L. The numerical model shows that the vertical chloride distribution is due to diffusion-controlled downward migration of seawater. The second marine unit obstructs the downward migration, indicating its low permeability and good aquitard integrity. The relatively fresh or brackish water in deep aquifers protected by the aquitard has the potential to be used as drinking water following some treatment, or at least as raw water with much cheaper desalinization compared with using seawater. The methodology and findings in this study are instructional for other coastal areas with similar geology and history in the South China Sea. © 2014, Springer-Verlag Berlin Heidelberg.

Shi L.,University of Hong Kong | Shi L.,Shenzhen Water Resources Planning and Design Institute | Jiao J.J.,University of Hong Kong
Environmental Earth Sciences | Year: 2014

Seawater intrusion has been an important topic in hydrogeology in China in recent decades. The rapid growth of the population and economy in the coastal regions has been consuming a tremendous amount of groundwater resources and has increased the extent of seawater intrusion. The spatial discrepancy of water resource distribution has caused the studies of seawater intrusion into China to mainly be concentrated on the area around the Bohai Sea in the northern part of China. The total area of seawater-intruded land due to excessive groundwater utilization in the area was estimated to be approximately 2,457 km2 in 2003. Great efforts have been made to mitigate the extent of seawater intrusion and to secure more freshwater resources, including building monitoring networks, subsurface barrier and groundwater reservoirs, and artificial infiltration facilities. Management projects over the years were evaluated to satisfy the objectives and to provide valuable experiences for future research and planning. It is expected that the coastal groundwater conditions of the northern region will improve through the development of a national water resource plan, such as the ongoing south-to-north water diversion project. © 2014, Springer-Verlag Berlin Heidelberg.

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