Abstract: The increased demands on water resources in northern China have had a significant impact on groundwater systems in the last three to four decades, including reductions in groundwater recharge capacity and overall water quality. These changes limit the potential for groundwater uses in this area. This paper discusses the issues surrounding groundwater system use in the eight basins of northern China as water resources have been developed. The results demonstrate that the recharge zone has shifted from the piedmont to the agricultural area, and that the total recharge rate in the basins tended to decrease. This decrease in arid inland basins was mainly caused by both the excessive use of water in the watershed area and irrigated channel anti-seepage. In semi-arid basins, the decrease observed in the groundwater recharge rate is related to an overall reduction in precipitation and increasing river impoundment. In addition, intensive exploitation of groundwater resources has resulted in disturbances to the groundwater flow regime in arid and semi-arid inland basins. Arid inland basins demonstrated fast falling groundwater levels in the piedmont plains resulting in declines of spring flow rates and movement of spring sites to lower locations. In the semi-arid basins, i.e. the North China Plain and the Song-nen Plain, groundwater depression cones developed and intersected regional groundwater flow. The semi-arid basins of the North China Plain and the Song-nen Plain have experienced significant hydrochemical evolution of groundwater characterized by changing water type including increase of TDS and pollutants.
Abstract: This paper targets its research at the exploitation–reinjection well of geothermal fluid of one geothermal heating project in Tianjin, China, examines such factors as ground temperature, CO2 partial pressure and stratum lithology, and simulates the changes in the main component contents of geothermal fluids mixed at different proportions in the exploitation and reinjection well. The research findings show that the mixed fluids are increasingly similar in nature to the reinjected water as the reinjection process goes on. It’s suggested that the manual method should be used to ensure the reinjected water has the similar mineralization as the exploited ground water in the process of reinjection and some acceptable adjustments should be made according to the specific component and water temperature. The study on water-rock balance calculation shows that PHREEQC can simulate the complicated chemical reactions related to water when the transfer of solute happens, so the necessary technological supports are given for the reasonable development and protection of geothermal resources.
Abstract: With the completion of South-North Water Transfer Project in China, plenty of high quality water will be transported to Beijing. To restore the groundwater level in Beijing, part of transferred water is planned to be used for artificial recharge. Clogging is an unavoidable challenge in the artificial recharge process. Therefore, a test is designed to analyse clogging duration and scope of influence and to test the reinjection properties of different recharge media. The test employs the self-designed sand column system with variable spacing and section monitoring, composed of four parts: Sand column, water-supply system, pressure-test system and flow-test system, to simulate the clogging of artificial recharge of sand and gravel pits. The hydraulic conductivity levels of all sand column sections are obtained to analyse the clogging of the injection of different concentrations in media of different particle sizes. In this experiment, two kinds of media are used–round gravel from sand and gravel pit in Xihuang village and the sand from sand and gravel pit by the Yongding River. The concentrations of recharge fluid are respectively 0.5 g/L and 1 g/L. The results show that clogging usually lasts for 20 hrs., and the hydraulic conductivity drops to the original 10%. Clogging usually occurs at 0–12 cm section of the sand column. The scope of influence is 0–60 cm. In column 3 and 4, whose average particle sizes are larger, section 20–50 cm also suffers from clogging, apart from section 0–12 cm. The effective recharge times are respectively 33 hrs. in column 1, 14 hrs. in column 2, 12 hrs. in column 3 and 12 hrs. in column 4. The larger the average particle size is, the quicker the clogging occurs. In media of larger particles, the change in suspension concentration does not have significant influence on the development of clogging. In conclusion, it is suggested that during artificial recharge, the conditions of reinjection medium should be fully considered and effective method of recharge be employed in order to improve effective recharge time.
Abstract: In order to assess the geological environment impact of a city landfill by the Yangtze River, soils from different depths in the dumpsite were sampled and analyzed. It was found that pollutants content at the site was distinctly higher than that in nearby environments. The content of heavy metals, such as Cd, Hg, As, Pb and Cu, reduces as depth increases; the content of elements F, Cl and N is the contrary. Pollutants migration driven by underground water flow was analyzed, considering the hydro-geological conditions of the site. It is believed that, due to leaching after rainfall infiltration, pollutants in the garbage layer migrates deeper, the cohesive soil in the underlying surface prevents them from spreading to the deeper aquifer; additionally, the high pressure tolerance of the deep groundwater is a key factor in preventing pollutants from entering the aquifer. Furthermore, human control has reduced the annual fluctuation range of water level in nearby rivers, weakening the hydrodynamic relations with phreatic water, and thus reducing the spreading of pollutants to nearby surface waters.
Abstract: After a comprehensive analysis for the influential factors like anti-erodibility chemical constitutes, mineral components and micro-structure characteristics of the Pisha-sandstone, and by combining AHP and grey correlation analysis, the anti-erodibility quantitative comparison for 5 types of Pisha-sandstones in Ordos is made on the basis of the grey multi-layer comprehensive assessment mode. The result shows that, from the anti-erodibility point of view, the order of those types is: Pink sandstone, celadon sandstone, purple sandstone, grey sandstone and commixed sandstone. For the evaluation process adopts a simple method, a direct, reasonable and practical result is given, which is also identical to the result of the field survey on soil and rock erosion problems. Consequently, the research on the Pisha-sandstone’s anti-erodibility issue is turned from the qualitative description process to the quantitative evaluation stage.
Abstract: The pattern of groundwater usage and industrial development in the Sanjiang Plain remains a concern of Chinese government. In accordance with the Water Conservancy Planning of the Sanjiang Plain, this paper presents a Sanjiang Plain resources allocation model which is established to be used in controlling water, land, ecology and economy in consideration of 50%-level and 75%-level years, planting structure adjustment, industry development by 2020, and different transit water exploitation schemes. Lingo10 global optimization has been adopted in solving the model. The results show that by 2020 the output of three industries will increase to a certain degree, the grain yields will satisfy state demand, and regional service value will decrease dramatically. Such results provide theoretical basis and practical significance for instructing the development and exploitation of the Sanjiang Plain.
Abstract: Research on the carrying capacity and security of water resources is vital for its contribution to implementing sustainable development goals. The limitation of water resources is one of the most important factors that influence the sustainable utilization of resources. Studying the carrying capacity of water resources will not only facilitate monitoring and forecast of national resources and environmental carrying capacity, but also be valuable for building ecological civilization. According to the principles of evaluation system, the carrying capacity of water resources on Shandong peninsula is explored. A comprehensive evaluation model of the carrying capacity of water resources is constructed based on the carrying capacity of water resources index and the composite of water resources index. The results show that the capacity of water resources on Shandong peninsula is generally consistent with overexploitation, and that the development and utilization of water resources has reached a considerable scale under existing economic and technological conditions. The carrying capacity of water resources in this region is relatively small, and the contradiction between supply and demand of water resources is alarming. Relative countermeasures are put forward, to improve the water resources carrying capacity and to provide a basis for future sustainable development and utilization of water resources in this region.
Abstract: Beishan region in Gansu was the preselected area for China’s high-level radioactive waste (HLW) repository. In selecting and evaluating a new dump site, the tritium study is of great significance. The Xinchang-Xiangyangshan preselected area in the Beishan area was taken as an example. This paper selects typical unit and tries to use the distribution characteristics of tritium in the soil to study the atmospheric precipitation infiltration recharge in this area. The results show: In this region, the spatial variability of the tritium content in surface soil is large; it is feasible to use bound tritium tracer method to study the theory of atmospheric precipitation infiltration recharge; the atmospheric precipitation infiltration has close relationship with the soil particle composition, salt content, mineral composition, water content and organic matter content. These results can provide important basis for developing the atmospheric precipitation infiltration recharge, groundwater numerical simulation, nuclide migration study and so on.
Abstract: Understanding the degree of sea/saltwater intrusion in coastal regions is of great significance to treating the intrusion and improving the environment. Based on the character analysis of the sea/saltwater intrusion, five factors were selected in the fuzzy-synthetical evaluation approach to form the index system, so as to evaluate the degree of sea/saltwater intrusion in southern Laizhou Bay. The results show that the sea/saltwater intrusion is stronger in the middle and northern areas and weaker on the sides and in southern area; currently, the intrusion is relatively serious, and the intrusion area has covered about 68.2% of the areas under study, among which the heavily intruded area is over 50%. Based on the factors analysis of the occurrence and development of sea/saltwater intrusion, the thesis proposes treatment measures.
Abstract: Marine sedimentary strata are widely distributed in the coastal zone of the study area, and are rich in brine resources. The exploitation of underground water resources often first caused the intrusion of salt water in the marine strata. Based on the analysis of sea-salt water intrusion feature, the sea-salt water intrusion is divided into four stages: The occurrence and development stage (1976–1985), the rapid development stage (1986–1990), the slow development stage (1990–2000) and the stable development stage (2000–2015). Based on the comparative analysis of the relationship between seawater intrusion and influencing factors, this paper presents that the groundwater exploitation and the brine resources mining are the main control factors of sea-salt water intrusion. On this basis, we have established a numerical model of the sea-salt water intrusion. Using this model, we predicted the development trend of the sea-salt water intrusion. The results show that if the current development of groundwater and brine is maintained, the sea-salt water intrusion will gradually withdraw; once development of brine stops, sea-salt water will invade again. This provides the scientific basis for the rational exploitation of groundwater and the prevention of sea-salt water intrusion.