Abstract. More population and less land is the main contradiction in the process of urbanization in China. Residential buildings developing upward and downward, such as the underground structure, not only made the impervious surface area increased, increasing more surface runoff, but also the underground impervious area increased, jointly cutting the connection between the rainfall infiltration and groundwater recharge and further reducing groundwater recharge and enhancing the heat island effect of the city. A case study of the construction of Jinan urban district puts forward the concept of underground impervious rate, evaluated effect of underground impervious rate on recharge of karst groundwater, analyzed the relationship between the actual impervious surface rate, calculating impervious surface rate and runoff. The result shows the impervious area after construction is an important factor which causes 93% of the loss of surface water recharging into karst groundwater compared with before construction. Finally, the concept of construction and development of water ecological community in Jinan was proposed according to the special geographical features and the construction of the pilot project of the sponge city in Jinan.
To study the influences of sand and gravel layer and groundwater velocity of Yufuhe River on atrazine migration, adsorption-desorption and sand column experiments were carried out. Results show that the adsorption capacity of montmorillonite, raw sand and washed sand to atrazine sequentially weakens. In different media, the time for atrazine concentrations to peak in washed sand with motomorillonite (WSM), raw sand and washed sand is 60, 135 and 105 minutes respectively, and the peak concentration accounts for 84, 90 and 95% of the initial concentrations. Under different flow rates, the peak time in washed sand at flow rates of 100, 150 and 200 mL/min is 135, 105 and 75 minutes, and the peak time in WSM is 90, 60 and 45 minutes, respectively. Results from this study indicate that increasing flow velocity and suspended colloids concentrations can promote the migration of atrazine in aquifers, while the presence of clay minerals in sand and gravel layer can reduce atrazine migration. Thus, during Yellow River water recharging, the sand and gravel layer of Yufuhe River is helpful to protect the aquifer, but the colloids-associated migration of atrazine can contaminate groundwater in underlying karst aquifer.
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