Research On Groundwater Circulation And Hydrochemical Evolution In Dakebo Lake Watershed In Ordos Basin

Although Ordos basin is one of the most significant energy and chemical industry base which is particularly well-known as it's mineral resources, arid and semi-arid climate conditions and lack of surface water that cause groundwater becoming the only source of local industry, agriculture and resident drinking water.To it is very urgently needed to study the water cycle and water chemistry of groundwater formation mechanism for guiding rational exploitation of groundwater resources.The Habor Lake is one of multitude lakes in Ordos Basin which control the local groundwater circulation, and it is Ordos Relict Gull National Nature Reserve. Groundwater is important and stedy source to maintain ecosystem of lake and wetland. but due to the different purpose of study in this area, groundwater circulation and hydrogeochemical evolution are never researched in small area like the Habor Lake area.The topic of this thesis for Master Degree is selected on the basis of National Natural Science Foundation of China-The behavior of sulfur biogeochemical in hyporheic Zone of desert lake-groundwater. This paper will reveal the circulation characteristics of groundwater in habor area by analysing the chemical and isotopic distribution of precipitation, surface water and groundwater. The formation of groundwater mechanism is analyzed by methods of hydrogeochemistry. isotope and inverse modeling of hydrogeochemistry. The results show the following conclusions.1. Compare theδ18O andδD in precipitation in the Habor Lake of Ordos Basin with global lines, the gradient and intercept is small. Because the study area is located with the strong evaporation, the slope and intercept of the local meteoric line are lower than that of global meteoric water line.δ18O and 8D in precipitation is higher in summer and lower in water. The 8D andδ18O of rain concentrated in wet season, and dispersed in dry season.2. Theδ18O andδD of lakes and groundwater are used to analyze the convers relationship among the lake. groundwater and precipitation. The habor lake water come from precipitation and groundwater by mud spring, it is discharged by evaporation.3. The regional groundwater circulation model will be given by the distribution of hydrogeochemical components and the isotopes:The Habor Lake control the less than 200m depth of groundwater circulation (shallow groundwater and mid-groundwater). The groundwater is recharged by precipitation in recharge area and effected by evaporation and transpiration in runoff way. especially the groundwater is effected by the strong evaporation in the surrounding of Habor Lake. Finally, the groundwater discharge to lakes. Confered the shallow groundwater age is less than 50 years.4.The concentration of TDS,Na+,Cl-and SO42- of shallow groundwater reduce from around to central area. while the concentration of Ca2- and Mg2- are opponent. and the concentration of HCO3- and NO3- is in high level in the whole area. The distribution of cation is transformed from Ca2+,Mg2+ to K-,Na-. while HCO3 is the mian anion along the groundwater flow direction. The chemical types is well distribution from Ca·Mg-HCO3, Ca·Mg·Na-HCO3 to Na-HCO3-Cl-SO4,Na-HCO35. Through the mineral saturation index. ion combination and ratio method confer the groundwater hydrogeochemistry formation were effected by lixiviation. evaporation function, cation alternative adhesive action, mixing action and the effect of man.6. Because the precipitation infiltration into the groundwater rapidly in recharge area and the CO2 of soil dissolve into groundwater in runoff way and discharge area. theδ13C of groundwater is close to CO2 of atmospheric in recharge area and theδ13C of groundwater is close to CO2 of soil in runoff way and discharge area.7. A inverse modeling of hydrogeochemistry in Habor Lake area has been carried out with NETPATH. and the simulation results show that:The chief actions are the solution of Gypsum, illite, Albite, K-feldspar, NaCl, CO2,the cation exchange, and the precipitation of calcite. Feldspar may be dissolution or precipitation on the simulated flow path by NETPATH...