The Chaobai River (CBR) basin in northern China is experiencing an unprecedented continuous inflow of external water via the South–North Water Diversion Project, which has channeled water from the southern part of the country to the north. Consequently, the steady rise of groundwater table in recent years is threatening soil salinity regulation. The purpose of this study was to describe the status of salinity of the surface soil in the CBR basin and to evaluate the impact of environmental factors including groundwater table on the spatial distribution of soil salinity using multivariate analysis (MVA) technique. In this study, 10 chemical variables of soil samples collected in 204 sites along CBR were analyzed, considering their interaction with three environmental factors: the density of irrigation canals, groundwater depth and topography. Statistical analysis mainly consisted of principal component analysis (PCA), redundancy analysis (RDA) and clustering analysis (CA). The results allow defining the surface soil in the CBR basin as a slightly saline and moderately alkaline media. The first two axes of multivariate model approximately explains 51% of the observed variability and allows distinguishing two main domains: the saline and the alkaline. The variability of the saline domain, defined by major cations and anions, is obviously controlled by macro environmental factors, of which the density of irrigation canals and groundwater depth contributes 71% and 28%, respectively, while that of the alkaline domain, related to pH and bicarbonate, mainly manifests as singular behaviors of soil groups like rice cultivation or sewage irrigation. The results suggests that more attention should be paid to the ongoing water table rise to help inform future land management decisions and to prevent a double threat of both groundwater and surface water on soil salinization. Meanwhile, this study shows the enormous potential of MVA technique, specifically the complementary duo of RDA and CA, for integrating both global and local information of soil salinity and environmental factors.

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Caofeidian sea area is an important ecoregion of Hebei province. It's meaningful to investigate the pollution situation of this area. Firstly, a numerical model of tidal flow and pollutant transport based on Delft3D-FLOW is established to simulate and analyze COD distribution in Caofeidian sea area. Then, the model is verified by measured data. Finally, the flow field and COD concentration in this area are analyzed, and general suggestion for control COD is presented.

It is important to analyze underground urban spaces for their capacity to meet the needs of urban development without compromising important ecological resources. Through analyzing the soil structure of Beisan County of Langfang City, the cohesive soil has low bearing capacity and easy deformation, which affects the development of underground space; the sand has wide distribution, large thickness and high bearing capacity, which is beneficial to the development of underground space. In 18-22 meters and 50-70 meters underground, there are two cohesive soils with continuous distribution, which are natural protective barriers for groundwater resources. In order to coordinate the development and utilization of underground space with the protection of groundwater resources, a safe method for utilizing space is proposed that protects groundwater resources and avoids breaking continuous aquiclude by stratifying the underground space. The underground space is developed in three sections in the study area: 0∼18 meters is the shallow underground space;22∼50 meters is the sub-deep underground space; Below 70 meters is the deep underground space.

Based on 59 groundwater samples which were collected on the south bank of Laizhou Bay, the main ionic ratios analysis and the main ionic Piper three-line diagram was done. The results show that from offshore to nearshore, groundwater hydrochemical is mainly freshwater, brackish water, salt water, and brine. And the ion type transforms from HCO3-Ca to HCO3·Cl-Ca, then converted to HCO3·Cl-Na and further transformed into Cl·HCO3-Na, then changed to Cl-Na regularity. By calculating some conventional water ion ratios which include Na/CL, K/CL, Ca/CL, SO4/CL, the hydrogeochemical effects of water-rock interactions, the source of groundwater salinity and the mechanism of groundwater salinization were investigated in this study. The anion-cation exchange reaction in the groundwater of the brackish water transition zone in the northern part of the monitoring section is more obvious than that in the southern underground freshwater. The main hydrogeochemical processes occurring in the brackish water transition zone are the dissolution of minerals (calcite, anhydrite and rock salt), precipitation of gypsum and dissipation of carbon dioxide. And the main cation exchange in this area is Ca-Na exchange.