Possibilities of Using Dam Reservoir Sediments in Earthworks

A possibility of using bottom sediments from dam reservoir as a material for earthen embankments was considered in the paper. It was stated that sediments cannot be used for road or hydrotechnical embankments without improving their geotechnical parameters. Thanks to low values of the permeability coefficient, they can be used for sealing elements in embankments or for low levees. In order to verify usability of this material for mentioned levees, stability and filtration calculations were carried out using Finite Element Method （FEM） analysis. It was stated the levee built from bottom sediments is stable even at the height of 8.0 m, despite the boundary conditions on the upstream side.

Simulation of Ground Motion at Guanting Reservoir Dam Based on the Scenario Earthquake in the Yanqing-Huailai Basin

Research at home and abroad shows that the simulation of ground motion using the 3D finite-difference method might be accurate and feasible. Based on related theories and methods,and using the wave velocity and density model of the crust in the Yanqing-Huailai Basin,this paper makes a simulation of ground motion at Guanting Reservoir Dam based on the scenario earthquake in the Yanqing-Huailai Basin. Comparative analysis shows that the results of 3D finite-difference simulation accord with those of the empirical formula. The parameters such as the velocity-time series of ground motion,PGV and frequency might be referred to for the analysis of seismic protection design of the dam's structure.

Geomatics-Based Framework for Assessing Environmental Impacts of Grand Ethiopian Renaissance Dam (GERD) Reservoir

Despite the benefits of big project dams, their reservoirs may have significant environmental impacts. The main objective of this paper is to develop an integrated analysis framework of remotely-sensed data ad GIS techniques for delineating surface area of the dam reservoir, simulating their capacities and assessing associated environmental impacts with application to Grand Ethiopian Renaissance Dam (GERD). For this purpose, a methodology of four main steps was applied. The methodology involved delineating the up-to-date reservoir using remotely sensed data, simulating reservoir at full capacity, estimating current and potential reservoir capacity and finally assessing environmental impacts of the reservoir. The results revealed that the up-to-date reservoir covers a total area of 330.3 km2 with a gross storage capacity of 12 billion m3. Under full capacity scenario, the reservoir is estimated to cover a total area of 1650.9 km2, with a storage capacity of 63.4 billion m3. The GERD reservoir may lead to dramatic changes in the local environment with significant implications at both regional and global scales. In this respect, it was found that the reservoir will lead to destruction of ecosystems in a total area of 1300 km2 covered by grasslands and Savannah. Also, the GERD reservoir is expected to have significant impacts on GHGs emissions and global warming. Moreover, a massive quantity of water is expected to be lost by surface evaporation.

Impacts of Agricultural Non-point Pollution on Water-source Area in Songhua Dam

[Objective] The aim was to research impacts of agricultural non-point pol- lution on water-source region in Songhua Dam, laying foundation for control of water pollution and scientific protection of water-source region. [Method] Water in Muyang River, lengshui River and Zizania aquatica region were sampled to measure content of pollutants in water and conclude relation between water contamination and agri- cultural non-point pollution to find the major cause of pollution. [Result] Organic pollu- tant in Muyang River was higher; N and P contents in Lengshui River were higher; the measured indices in Zizania aquatica region excessively exceeded related stan- dard. [Conclusion] The chemical fertilizers and pesticides are the toxic materials lead- ing to water contamination and constitute a major cause of pollution in Songhua Dam water-source region. Agricultural non-point pollution should be controlled in a scientific way.

Seasonal and interannual variations of flow discharge from Pearl River into sea

Flow discharge from the river basin into the sea has severe impacts on the immediate vicinity of river channels, estuaries, and coastal areas. This paper analyzes the features and temporal trends of flow discharge at Pearl River＇s three main gauge stations： the Wuzhou, Shijiao, and Boluo gauge stations on the West River, North River, and East River, respectively. The results show no significant trend in annual mean discharge into the sea at the three gauge stations. Changes of monthly mean discharge at the Boluo Gauge Station are evident, and a majority of monthly discharge in the dry season displays significant increasing trends. Furthermore, changes of the extreme discharge are quite evident, with a significant decreasing trend in the annual maximum discharge and a significant increasing trend in the minimum one. The significantly decreasing ratio of the flood discharge to annual discharge at the Boluo Gauge Station indicates that the flow discharge from the East River has increased in the dry season and decreased in the flood season since the construction of dams and reservoirs. At the other two gauge stations, the Wuzhou and Shijiao gauge stations, the seasonal discharge generally does not change perceptibly. Human impacts, especially those pertaining to reservoir and dam construction, appear to be responsible for the seasonal variation of flow discharge. The results indicate that the construction and operation of dams and reservoirs in the East River have a greater influence on flow discharge, which can well explain why the seasonal variation of flow discharge from the East River is more evident.

Some Remarks about the Deployment of Floating PV Systems in Brazil

Floating photovoltaic systems installed in water bodies such as natural lakes or dams reservoirs, have attracted increased worldwide attention since 2011 and have already been deployed in several countries, including Japan, South Korea and USA. In Brazil, pilot-projects were announced in the reservoirs of hydroelectric power plants of Balbina （State of Amazonas） and Sobradinho （State of Bahia）. Several advantages, not necessarily valid in Brazil, are mentioned for deploying this kind of technology, such as an increase in energy generation, reduction of water losses through evaporation, low environmental impact, no occupation of land etc. In this article, several of these allegations are analyzed preliminarily under the Brazilian point of view, and relevant considerations are presented. It is concluded that the technical and economic advantages of floating photovoltaic systems are not yet clear in Brazil and that pilot projects, such as those under way, should be used to clarify several important aspects related to them.

Effect of a seasonal diffuse pollution migration on natural organic matter behavior in a stratified dam reservoir

This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter （NOM） in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from diffuse sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms of dissolved organic matter （DOM） including refractory dissolved organic carbon （RDOC） and labile DOC and also well explained the internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM affected organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the dam reservoir, appropriate dam water discharge gate operation provided effective measurement. Because of the gate operation let avoid the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time.

Algorithms for intelligent prediction of landslide displacements

Landslides represent major threats to life and property in many areas of the world,such as the landslides in the Three Gorges Dam area in China's Mainland.To better prepare for landslides in this area,we explored how several machine learning algorithms(long short term memory(LSTM),random forest(RF),and gated recurrent unit(GRU))might predict ground displacements under three types of landslides,each with distinct step-wise displacement characteristics.Landslide displacements are described with trend and periodic analyses and the predictions with each algorithm,validated with observations from the Three Gorges Dam reservoir over a one-year period.Results demonstrated that deep machine learning algorithms can be valuable tools for predicting landslide displacements,with the LSTM and GRU algorithms providing the most encouraging results.We recommend using these algorithms to predict landslide displacement of step-wise type landslides in the Three Gorges Dam area.Predictive models with similar reliability should gradually become a component when implementing early warning systems to reduce landslide risk.

Wetland loss in Turkey over a hundred years:implications for conservation and management

The aims of this study were to provide a complete inventory of wetlands in Turkey including their past status(1910-1930)in comparison to the present time(2014).The types of wetlands and their area sizes were determined by using cartographical maps of 1/200,000 in scale made between 1910s and 1920s vs.2006 CORINE Land Cover data,which were updated with Landsat 8 satellite images in 2014.The effect of possible climate change on wetlands sizes various local,national and regional rainfall datasets were analysed by correlation and regression analysis.A hundred years ago,the total number of natural wetlands was 1299 with a total surface area of 1,376,505 hectares.In 2014,the total number of natural wetlands had decreased to 900,with a total surface area of 1,085,936 hectares,so that 21.2%of the original wetlands were lost(291,339 hectares).The observed changes in the number of wetlands and their relative sizes cannot be attributed directly to changes in climate.Wetland drainage was largely responsible for observed wetland losses,but local changes in precipitation regimes partially contributed to this loss.Urgent conservation and restoration of wetlands are recommended to avoid further loss of wetlands in Turkey.

An experimental study on plunging depth of density currents

Mass density of the current flows is the one of the important problem in the hydraulics of the dam reservoir. Plunge point occurs when the mass density current penetrates in the stagnant fluid. Recognition the place of this point is very important because of clearing the boundary of the density current flow and ambient fluid. In this study the influences of bed slope and hydraulic parameters on plunging depth were experimentally investigated. The results show that the slope has a minor effect on the plunging depth. The height of plunging depth is increased by increasing the density of the current flow. Also increasing the densimetric Froude number caused of decreasing the plunging depth. Finally an equation was proposed to estimate the plunging depth using as function of flow characteristics.