Distribution,characteristics and influencing factors of fresh groundwater resources in the Loess Plateau,China

The fresh groundwater in the Loess Plateau serves as a major source of water required for the production and livelihood of local residents and is greatly significant for regional economic and social development and ecological protection.This paper analyzes the hydrogeological conditions and groundwater characteristics in the Loess Plateau,expatiates on the types and distribution characteristics of the fresh groundwater in the plateau,and analyzes the influencing factors and mechanisms in the formation of the fresh groundwater in the plateau as a priority.Based on this,it summarizes the impacts of human activities and climatic change on the regional fresh groundwater.The groundwater in Loess Plateau features uneven temporal-spatial distribution,with the distribution space of the fresh groundwater closely relating to precipitation.The groundwater shows a distinct zoning pattern of hydrochemical types.It is fresh water in shallow parts and is salt water in deep parts overall,while the fresh water of exploration value is distributed only in a small range.The storage space and migration pathways of fresh groundwater in the loess area feature dual voids,vertical multilayers,variable structure,poor renewability,complex recharge processes,and distinct spatial differences.In general,the total dissolved solids(TDS)of the same type of groundwater tends to gradually increase from recharge areas to discharge areas.Conditions favorable for the formation of fresh groundwater in loess tablelands include the low content of soluble salts in strata,weak evaporation,and special hydrodynamic conditions.Owing to climate change and human activities,the resource quantity of regional fresh water tends to decrease overall,and the groundwater dynamic field and the recharge-discharge relationships between groundwater and surface water have changed in local areas.Human activities have a small impact on the water quality but slightly affect the water quantity of the groundwater in loess.

Applying multivariate statistics for identification of groundwater chemistry and qualities in the Sugan Lake Basin, Northern Qinghai-Tibet Plateau, China

The Sugan Lake Basin is located in the inland arid region of northwestern China,in which groundwater is of great significance to human and ecology.Therefore,it is necessary to understand the chemical characteristics and quality of groundwater in the basin.Based on samples collected from 35 groundwater wells in Sugan Lake Basin,the spatial distribution characteristics of groundwater chemistry,main hydrogeochemical processes and groundwater quality have been discussed in this paper by using the multivariate statistics and hydrochemistry analysis methods.The results showed that the groundwater is weakly alkaline,and its total dissolved solid(TDS)and total hardness(TH) are high,with the average values of 1244.03 mg/L and 492.10 mg/L,respectively.The types of groundwater are mainly HCO_3^--SO_4^(2-)-Ca^(2+)type in the runoff area and Cl^--SO_4^(2-)-Na^+type in the catchment area.Rock weathering and ion exchange are the main controlling factors of regional groundwater chemistry,followed by evaporative crystallization,and human activities have less impact on groundwater.The spatial difference of groundwater quality is obvious,the water quality of the catchment area is not suitable for drinking,and the suitability for plant growth is also poor.The groundwater in the runoff area can be used for drinking,but the hardness is slightly higher,which is more suitable for ecological purpose.

Landslide mapping and analysis along the China-Pakistan Karakoram Highway based on SBAS-InSAR detection in 2017

The Karakoram Highway(KKH),a part of the China–Pakistan Economic Corridor(CPEC),is a major highway connecting northern Pakistan to China.The inventorying and analysis of landslides along KKH are challenging because of poor accessibility,vast study area,limited availability of ground-based datasets,and the complexity of landslide processes in the region.In order to preserve life,property,and infrastructure,and to enable the uninterrupted and efficient operation of the KKH,it is essential to strengthen measures for the prevention and control of geological disasters.In the present study,SBASInSAR(Small Baseline Subsets-Interferometric Synthetic Aperture Radar)was used to process 150 scenes of Sentinel 1-A images in the year 2017 along the Karakoram Highway.A total of 762 landslides,including 57 complex landslides,126 rock falls,167 debris slides,and 412 unstable slopes,ranging in size between 0.0017 and 10.63 km2 were identified.Moreover,this study also gains an inventory of 40 active glacier movements in this region.Landslide categorization,displacements characteristics,spatial distribution,and their relationship with various contributing factors have been successfully investigated along the entire KKH using image interpretation and frequency-area statistics.The criteria adopted for landslides categorization is presented in the study.The results showed that the 2-D ground deformation derived in Hunza valley echoes well with the general regional landslides characteristics.The spatial distribution analysis revealed that there are clumped distributions of landslides in the Gaizi,Tashkurgan,and Khunjerab in China,as well as in Hunza valley,and north of Chilas city in Pakistan.Statistical results indicated that these landslides mainly occur on south-facing slopes with a slope angle of 20°–45°and elevation relief of 550–2,100 m.Landslide development is also related to low vegetation cover and weathering effects in mountain gullies.Overall,our study provides scientific data support and theoretical references for prevention,control,and mitigation of geological disasters in the Karakoram region.