| Title: | Nitrogen retention effects under reservoir regulation at multiple time scales in a subtropical river basin |
| Authors: | Liu, M., X. Chen, Y. Chen, L. Gao and H. Deng |
| Year: | 2019 |
| Journal: | Water |
| Volume (Issue): | 11(8) |
| Pages: | |
| Article ID: | 1685 |
| DOI: | 10.3390/w11081685 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | nitrogen cycling/loss and transport |
| Secondary Application Category: | hydrologic assessment |
| Watershed Description: | 1,023 km^2 Shanmei Reservoir drainage area, located in southeast China. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Reservoirs are an important nitrogen sink as a result of their retention effect, but their
retention performance may vary with hydrologic conditions with time-varying characteristics,
which also change them from being a sink to source over time. This study uses a coupled modelling
system (Soil and Water Assessment Tool (SWAT) and a two-dimensional hydrodynamic and water
quality model (CE-QUAL-W2) to analyze the nitrogen retention effect and influential factors at
annual, monthly, and daily scales in Shanmei Reservoir in southeast China. The results showed that
there was a positive retention effect of total nitrogen (TN), nitrate-nitrogen (NO3-N) and ammonia
nitrogen (NH4-N) in most years, with average retention rates up to 12.7%, 7.83% and 26.17%,
respectively. The reservoir serves mainly as a nitrogen sink at an annual scale. The monthly
retention performances of TN and NO3-N were observed during the wet season (April–October)
with higher water temperature and lower velocity, while a release effect occurred during the dry
season (November–March). For NH4-N, which is prone to nitrification, the retention effect lasted
longer, from May to December. The daily nitrogen retention process changed more dramatically,
with the retention rate varying from -292.49 to 58.17%. During the period of dispatch, the regulated
discharge was the primary factor of daily retention performance, while the hydraulic residence time,
velocity and water level were all significantly correlated with nitrogen retention during the period
without dispatch. |
| Language: | English |
| Keywords: | nitrogen retention; release effect; reservoir regulation; multiple time scales; hydrodynamic
factors |