Groundwater Cycle Along Luan River

The drainage basin of Luan River is one of the most water shortage districts in China.The water-supply source is single and the reserve water is scare in the area. These problemsconfine the harmonious development of social economy. Therefore, exploring thegroundwater cycle and finding out the interaction relationship between groundwater andsurface water are important and realistic significance for regional water resource managementand reasonable exploitation.On the basis of the existed achievements of this area, this paper selected typical profilesand was guided by groundwater system theory to explore the patterns of groundwatercirculation with field investigation and lab analysis coupling the methods of environmentalisotope, hydro-geochemistry and numerical simulation. The results are as follows:(1) The river water is characterized by HCO3SO4type with low TDS, and is notsignificant zoning character.Whereas, the TDS of shallow groundwater is increasing along thebank of Luan River; and the hydro-chemical type changes from HCO3type to HCO3SO4type and finally to Cl HCO3.(2) There is a close hydraulic connection between river water and groundwater.In theintermountain basin, groundwater recharges the river; whereas in the alluvial-proluvial plain,the river recharges groundwater inversely. From the downstream of alluvial-proluvial plain toestuary, there exist different relations from the above patterns—river groundwater rechargingriver water on the left bank and oppositely on the right bank.(3) The groundwater is recharged by precipitation, and discharges through human’swithdrawals and evaporation. At some different sites, there exist different relations betweenriver water and groundwater. The groundwater cycle patterns mainly include three types.①Inthe intermountain basin, groundwater is recharged by precipitation, whereas discharged toriver. Its circulation is strong with a fast renewal rate; groundwater age is young (less40years).②In the upstream of alluvial-proluvial plain, groundwater is recharged by river waterand precipitation; the runoff rate becomes slow with the speed of0.15–0.25m/d, but therenewability is still strong.③In the downstream of alluvial-proluvial plain and marine depositional plain, the permeability became poor, and groundwater is recharged byprecipitation. The runoff rate of groundwater becomes further slow with the speed of0.05m/d,and the renewability is weak. In this area, groundwater was recharged by river on left bank,however discharged to river on the right bank.(4)The upstream of alluvial-proluvial plain is suitable as reserve water-supply source.Pumping groundwater in this zone will strengthen the recharge from river to groundwater, andat the same time, low the evaporation. Additionally, it could not induce seawater intrusion.There will benefit the sustainable development of environment and water resource.