Numerical modelling to evaluate the nitrogen removal rate in hyporheic zone and its implications for stream management

Liu, Suning1,2; Chui, Ting Fong May1

2019-07-25

10.1002/hyp.13548

HYDROLOGICAL PROCESSES   影响因子和分区

0885-6087

1099-1085

The hyporheic zone (HZ) plays a vital role in the stream ecosystem. Reactions in the HZ such as denitrification and nitrification have been examined in previous studies. However, no numerical model has yet been developed that can accurately simulate nitrogen concentration changes in the HZ, because the zones for the two reactions can change throughout the reactions. This study proposes a method of evaluating the nitrogen removal rate in the HZ through numerical modelling. First, a basic two-dimensional numerical model coupling flow conditions with biochemical reactions is proposed to consider both nitrification and denitrification. The zones for different reactions are determined under the assumption that related environmental variables (i.e., the dissolved oxygen) will not change throughout the reactions. Next, to examine changes in environmental variables throughout the reactions, an improved model is proposed, and a method is developed for delineating the boundary between nitrification and denitrification zones and identifying a transition zone where either reaction might take place. However, more information about biochemical reactions in the HZ is required to use the improved model. To overcome this shortcoming, a new model that couples the basic model and genetic programming (GP) is proposed to optimize the simulation results of the basic model and allow for real-time forecasting. The results show that the basic model obtains acceptable simulation results for nitrate concentration distribution in the HZ. The improved model performs better than the basic model, but the model coupling the basic model with GP performs best. In addition, the function of the HZ in nitrogen removal is examined through a case study of four scenarios, leading to the conclusion that the HZ has a higher nitrogen removal rate when water quality is neither too poor nor too good. Overall, this study enhances our understanding of the HZ and can benefit the restoration and management of HZs and streams in the face of the continual degradation caused by human activity.

denitrification genetic programming hyporheic restoration hyporheic zone nitrification stream management

SCI ; EI

英语

其他

Research Grants Council of the Hong Kong Special Administrative Region, China[HKU17203815]

Water Resources

Water Resources

WOS:000479331200001

WILEY

20193107257160

Denitrification ; Dissolved oxygen ; Ecosystems ; Genetic algorithms ; Genetic programming ; Nitrification ; Nitrogen removal ; Numerical methods ; Restoration ; Stream flow ; Water quality

Waterways:407.2 ; Water Analysis:445.2 ; Ecology and Ecosystems:454.3 ; Computer Programming:723.1 ; Chemical Reactions:802.2 ; Mathematics:921 ; Numerical Methods:921.6

ENVIRONMENT/ECOLOGY

Web of Science

1.Univ Hong Kong, Dept Civil Engn, Room 6-18A,Haking Wong Bldg, Hong Kong, Peoples R China
2.Southern Univ Sci & Technol, Sch Environm Sci & Engn, State Environm Protect Key Lab Integrated Surface, Shenzhen, Guangdong, Peoples R China

Liu, Suning,Chui, Ting Fong May. Numerical modelling to evaluate the nitrogen removal rate in hyporheic zone and its implications for stream management[J]. HYDROLOGICAL PROCESSES,2019,33(24):3084-3097.

Liu, Suning,&Chui, Ting Fong May.(2019).Numerical modelling to evaluate the nitrogen removal rate in hyporheic zone and its implications for stream management.HYDROLOGICAL PROCESSES,33(24),3084-3097.

Liu, Suning,et al."Numerical modelling to evaluate the nitrogen removal rate in hyporheic zone and its implications for stream management".HYDROLOGICAL PROCESSES 33.24(2019):3084-3097.