Feasible ways promoting nitrogen removal in riparian zone
downstream of a regulated river
Set in the downstream riparian zone of Xin’an River Dam, this paper established a two-dimensional coupling flow and solute transport and reaction model, and explored the denitriding methods and principles in the riparian zone from the perspective of hyporheic exchange, which provided a basis for the engineering techniques for river ecological restoration. Our studies have shown that under the condition of water level fluctuation, biological method such as adding denitrifying bacteria biomass could greatly increase the denitriding rate in the riparian zone; chemical methods such as adding organic carbon into the surface water or groundwater could increase the total riparian nitrogen removal and its efficiency to a certain extent; hydrogeological methods such as silt cleaning of the aquifer surface or local pumping around the contaminated area could increase the total riparian nitrogen removal to some extent, but correspondingly reduce the denitriding efficiency; physical methods such as designing the bank form into gentle slope or concave shape could slightly increase the total riparian nitrogen removal and correspondingly improve the denitriding efficiency. At the application level of river ecological restoration, integratedly adopting the above methods can make the riparian denitriding effect “fast and good”.