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Effects of the Japanese Nitrate Directive Plan (NDP) to curb groundwater nitrate-nitrogen content in the Miyakonojo River basin

Yu, Zhi Qiang ; Nakagawa, Kei LU orcid ; Berndtsson, Ronny LU orcid ; Hiraoka, Toru and Suzuki, Yoshihiro (2022) In Journal of Hydrology 615.
Abstract

There are urgent needs to evaluate different management techniques to improve groundwater quality. To maintain a good quality of groundwater in the Miyakonojo River Basin (MRB), Japan, the Nitrate Directive Plan (NDP) was implemented in 2004. To assess the efficiency of this plan, we performed multivariate times-series analyses on 26 years (1996–2021) of groundwater nitrate-nitrogen (NO3−-N) data from up to 584 groundwater wells. Results showed that wells with an increasing NO3−-N trend (p ≤ 0.05) increased from 5.8% in 1996 to 13.8% in 2009 and thereafter leveled off with time. The number of groundwater wells with a decreasing NO3−-N trend (p ≤ 0.05) increased from 18.7%... (More)

There are urgent needs to evaluate different management techniques to improve groundwater quality. To maintain a good quality of groundwater in the Miyakonojo River Basin (MRB), Japan, the Nitrate Directive Plan (NDP) was implemented in 2004. To assess the efficiency of this plan, we performed multivariate times-series analyses on 26 years (1996–2021) of groundwater nitrate-nitrogen (NO3−-N) data from up to 584 groundwater wells. Results showed that wells with an increasing NO3−-N trend (p ≤ 0.05) increased from 5.8% in 1996 to 13.8% in 2009 and thereafter leveled off with time. The number of groundwater wells with a decreasing NO3−-N trend (p ≤ 0.05) increased from 18.7% in 1996 to 52.5% in 2021. These groundwater wells are primarily distributed in urban and agricultural production areas near rivers. However, the annual change rate of NO3−-N content displayed both increasing and decreasing NO3−-N trend (p ≤ 0.05) over time. But most importantly, the number of groundwater wells exceeding the environmental maximum permissive value reduced by > 60% from 2004 to 2021. Thus, there is statistical evidence that NDP has improved the groundwater quality regarding NO3−-N at the regional basin scale and that nitrogen levels are gradually being reduced.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Groundwater quality, Nitrate-nitrogen, Soil management, Trend analysis
in
Journal of Hydrology
volume
615
article number
128563
publisher
Elsevier
external identifiers
  • scopus:85141407719
ISSN
0022-1694
DOI
10.1016/j.jhydrol.2022.128563
language
English
LU publication?
yes
id
1a3fca5e-c367-41e2-96ff-ed3164eed7e3
date added to LUP
2022-12-05 12:43:12
date last changed
2023-10-09 11:07:30
@article{1a3fca5e-c367-41e2-96ff-ed3164eed7e3,
  abstract     = {{<p>There are urgent needs to evaluate different management techniques to improve groundwater quality. To maintain a good quality of groundwater in the Miyakonojo River Basin (MRB), Japan, the Nitrate Directive Plan (NDP) was implemented in 2004. To assess the efficiency of this plan, we performed multivariate times-series analyses on 26 years (1996–2021) of groundwater nitrate-nitrogen (NO<sub>3</sub><sup>−</sup>-N) data from up to 584 groundwater wells. Results showed that wells with an increasing NO<sub>3</sub><sup>−</sup>-N trend (p ≤ 0.05) increased from 5.8% in 1996 to 13.8% in 2009 and thereafter leveled off with time. The number of groundwater wells with a decreasing NO<sub>3</sub><sup>−</sup>-N trend (p ≤ 0.05) increased from 18.7% in 1996 to 52.5% in 2021. These groundwater wells are primarily distributed in urban and agricultural production areas near rivers. However, the annual change rate of NO<sub>3</sub><sup>−</sup>-N content displayed both increasing and decreasing NO<sub>3</sub><sup>−</sup>-N trend (p ≤ 0.05) over time. But most importantly, the number of groundwater wells exceeding the environmental maximum permissive value reduced by &gt; 60% from 2004 to 2021. Thus, there is statistical evidence that NDP has improved the groundwater quality regarding NO<sub>3</sub><sup>−</sup>-N at the regional basin scale and that nitrogen levels are gradually being reduced.</p>}},
  author       = {{Yu, Zhi Qiang and Nakagawa, Kei and Berndtsson, Ronny and Hiraoka, Toru and Suzuki, Yoshihiro}},
  issn         = {{0022-1694}},
  keywords     = {{Groundwater quality; Nitrate-nitrogen; Soil management; Trend analysis}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Hydrology}},
  title        = {{Effects of the Japanese Nitrate Directive Plan (NDP) to curb groundwater nitrate-nitrogen content in the Miyakonojo River basin}},
  url          = {{http://dx.doi.org/10.1016/j.jhydrol.2022.128563}},
  doi          = {{10.1016/j.jhydrol.2022.128563}},
  volume       = {{615}},
  year         = {{2022}},
}