Understanding nitrogen transport in the unsaturated zone with fluctuations in groundwater depth
Jianmin Bian,
Qian Wang,
Siyu Nie,
Hanli Wan,
Juanjuan Wu
Affiliations
Jianmin Bian
Key Laboratory of Groundwater Resources and Environment (Ministry of Education), Jilin University, Changchun, Jilin 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun, Jilin 130021, China; and College of New Energy and Environment, Jilin University, Changchun, Jilin 130021, China
Qian Wang
Key Laboratory of Groundwater Resources and Environment (Ministry of Education), Jilin University, Changchun, Jilin 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun, Jilin 130021, China; and College of New Energy and Environment, Jilin University, Changchun, Jilin 130021, China
Siyu Nie
College of Water Conservancy & Environment Engineering, Changchun Institute of Technology, Changchun, Jilin 130012, China
Hanli Wan
Key Laboratory of Groundwater Resources and Environment (Ministry of Education), Jilin University, Changchun, Jilin 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun, Jilin 130021, China; and College of New Energy and Environment, Jilin University, Changchun, Jilin 130021, China
Juanjuan Wu
Key Laboratory of Groundwater Resources and Environment (Ministry of Education), Jilin University, Changchun, Jilin 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun, Jilin 130021, China; and College of New Energy and Environment, Jilin University, Changchun, Jilin 130021, China
Fluctuations in groundwater depth play an important role and are often overlooked when considering the transport of nitrogen in the unsaturated zone. To evaluate directly the variation of nitrogen transport due to fluctuations in groundwater depth, the prediction model of groundwater depth and nitrogen transport were combined and applied by least squares support vector machine and Hydrus-1D in the western irrigation area of Jilin in China. The calibration and testing results showed the prediction models were reliable. Considering different groundwater depth, the concentration of nitrogen was affected significantly with a groundwater depth of 3.42–1.71 m, while it was not affected with groundwater depth of 5.48–6.47 m. The total leaching loss of nitrogen gradually increased with the continuous decrease of groundwater depth. Furthermore, the limited groundwater depth of 1.7 m was found to reduce the risk of nitrogen pollution. This paper systematically analyzes the relationship between groundwater depth and nitrogen transport to form appropriate agriculture strategies. HIGHLIGHTS The total leaching loss of nitrogen increases with the decrease of groundwater depth.; The limited groundwater depth is proposed for determining appropriate agriculture strategies.;
