Advanced Materials Research Vols. 518-523

Abstract: Using the satellite altimetric sea level data during 1992 to 2009 from AVISO, analyzed seasonal, annual variations of vortexes in northeast Taiwan (24°N ~ 27°N, 120°E ~ 124°E). The result shows that: (1) Cyclonic and anti-cyclonic eddies are found in research area and had significant seasonal variation; (2) Cyclonic eddies had five-years cycle in winter; (3) Cyclonic eddies and anti-cyclonic eddies often appeared in pairs and swing in the east-west direction simultaneously; (4) Changes in spatial distribution of the eddies are the result from the Kuroshio’s period oscillation and the topography at northeast of Taiwan.

Abstract: To solve water disasters of coal seam bottom in the 8th coal mine, with the analysis on the bottom aquifer characteristics, the water inrush coefficient method was applied to evaluate the dangers of the aquifer floor and to the dangers division of water inrush. In combination with the karst fracture development conditions of the aquifer, we designed the water prevention and control plan of the limestone water under the seam floor. All the schemes set the basis for the mine safety production.

Abstract: The effect of initial water content on water transport characteristics in injection irrigation is analyzed through an indoor experiment of injection irrigation in different initial water contents. The research shows the following results. The relationship between the cumulative infiltration and time accords with power function. The higher the initial water content is, the bigger the cumulative infiltration is in the same time. The wetting front is a semi-circle with its center below the water outlet, the transport velocity of which slows down with the passing of time. The transport velocity of vertical section crossing the middle of the two outlets approaches that of vertical section at the middle point of the central line of the two outlets. The higher the initial water content is, the shorter the time of the transport velocity of the two sections similar to each other is. The water wetted range is comparatively wider, and the water content is comparatively higher below the outlet, and it is reverse above the outlet. The higher the initial water content is, the wider the wetted range is and the higher the water content of the soil being the same distance from the outlet is. The above research provides a basis for supplementing the theories and technologies of injection irrigation.

Abstract: The hydrological cycling of groundwater in Ordos Cretaceous Basin show obvious stratification, the cycle can be divided into three layers by cycling depth, the shallow, the intermediate and the deep. In this paper, a classification standard formed with geochemical and isotopic information is described. The standard is based on a large number of borehole investigation and stratified sampling. In the shallow layer, the groundwater mostly is fresh water with lower amount of total dissolved solids, the dominated anion is HCO₃,tritium and ¹⁴C features show a high or rich properties; in the intermediate layer, the geochemical type of groundwater are SO₄ or SO₄-Cl, the age of groundwater calculated by ¹⁴C is less than 5000a; in the deep groundwater cycling, dominated anion show a complete evolution processes along the flow direction (HCO₃-SO₄-Cl) from recharge to discharge area, the groundwater age is commonly bigger than 5000a and even bigger than 10000a in the discharge area.

Abstract: The resolution of digital elevation model (DEM) has important effects on topographic parameters and accuracy of hydrological simulation. Taking Huangshui river basin as an example, the 11 kinds of DEM resolution data are used for studying relationships between DEM resolution and hydrological simulation by Soil and Water Assessment Tool (SWAT) based on ArcGIS9.2. The results show that watershed area, the longest channel, total channel length, river network density and slope show downward trend with DEM grid size increasing. The slope change significantly, the maximum slope and average slope drop by 107.76% and 30.56%, respectively. Keeping other parameters of SWAT unchanged, the results of hydrological simulation reveal that runoff change slightly, dropping by 2.05%, but sediment yield decrease significantly, reducing by 41.72% with DEM grid increasing from 10 m to 130m. The results provide the theoretical basis for selecting the appropriate DEM resolution data in the hydrological simulation.

Abstract: An enclosure experiment was conducted to evaluate the processes involved in algal bloom formation at different trophic levels in Chaohu Lake, which is a large hyper-eutrophic shallow lake in China. In situ investigations were conducted concurrently to quantitatively describe the effects of wind on the horizontal transference and vertical hybridization of algal blooms. The results revealed that certain nutrient trophic levels played a crucial role in the formation of algal blooms. Specifically, sediments were identified as an important source of nutrients and algal seeds that are necessary to maintain the trophic level and growth of algal blooms. In addition, the disturbance caused by wind accelerated the multiplication of algae, as well as their sedimentation and suspension at the water-sediment interface. Furthermore, when the wind speed was less than 3m•s-1, algal clusters drifted on the water surface at a speed that was exponentially related to the wind velocity with a coefficient of 0.9052. When the wind speed was greater than 3m•s-1, the algae mixed together vertically and then sank. The algal bloom distribution in the lake was dominated by leading wind directions. Moreover, the algal biomass of the surface lake water in leeward areas was 8.8 times greater than the biomass in the windward areas during the study period.

Abstract: Located in an arid and semi-arid region with low rainfall and high evaporation, the Subei Lake watershed has fragile ecological environment; the impact of groundwater level recession on vegetation ecology is the key problem for the exploitation and utilization of groundwater resource in this region. In this paper, a succession model for vegetation and burial depth of groundwater level was constructed through field survey, and was used along with numeric simulation to predict the change in burial depth of groundwater level in the study area under exploitation and to analyze and predict the vegetation succession rules and processes. It is believed from the study that, while groundwater level falls constantly, the burial depth of groundwater level will increase gradually, and succession will occur gradually from aquatic vegetation to mesophytic and xerophytic vegetations, from Carex L. and Iris ensata Thunb shoaly lands to Achnatherum splendens shoaly lands, from Salix psammophila shrubs to Artemisia desterorum Spreng shrubs, and from Populus simonii to Salix matsudana.

Abstract: This research takes the land subsidence in Xixi-Chengnan area, Jiangsu province as a case study, quantifies the relative land subsidence vulnerability in terms of vulnerability degree and determines the numerical classification of vulnerability level at the township scale based on the constructed subsidence vulnerability assessment framework, and the detail analysis of natural geographical environment and regional socio-economic conditions in the study area. The vulnerability assessment process is quantitative, objective and comprehensive, provides effective information for the systematic study of land subsidence in Xixi-Chengnan area, lays the foundation for planning of regional land subsidence disaster prevention and reduction, and is worthy of learning for the whole Su-Xi-Chang area and even other subsidence areas.

Abstract: The middle and lower reaches of the Yangtze River is an important base for producing grain, cotton and oil plants, one of the most rapidly developing areas economically in China. Along with the rapid development of the economy, its environmental quality related to water, soil and atmosphere decline rifely and obviously compared with that in twenty years ago. In the meantime, flood menace still exists, drought and waterlogging coexists, and water environment and water ecology have been deteriorating. This paper emphasized more important issues related to the regional water environment and water ecology, and put forward corresponding countermeasures based on domestic and foreign experiences, so as to drive social-economy sustainable development of the region.

Abstract: Wetland is one of the most diverse ecosystem and important habitats. However, degradation and loss of wetlands increased with anthropologic factors. Thus, the research of wetland restoration has become the emphasis and imperative issue. Water plays an important role in ecological evolution of the wetlands, and water requirement is a key step for water resource management of wetland restoration engineering. This research deals with the analysis of water requirement for wetland restoration engineering in a case study in Bohai Bay. The results show that the total water requirement in the study area are (0.18~0.28)×109m3, (0.54~0.81)×109m3, (1.21~1.41)×109m3 to reach the basic objective, moderate objective and perfect objective, respectively.