Abstract
In order to help evaluate the trends in the NO3-N concentration in groundwater with a view to preventing further degradation in water quality in the future, a distributed groundwater quality model was constructed for the Nasunogahara basin. The best fit for the groundwater table elevations by the flow component of the model was achieved with average mean absolute errors (MAEs) of 0.92 m for the calibration period and 0.83 m for the validation period. Moreover, the best fit for the NO3-N concentration by the water quality component was achieved with average mean relative errors (MREs) of 29.8% for the calibration period and 30.3% for the validation period. After developing a robust model, various change scenarios were tested; specifically, the effects of effluent load control and a decrease in paddy field area on the NO3-N concentration in groundwater were predicted. The most intensively farmed area contributed about 40% of the total effluent load because of livestock farming in the basin. When the effluent load from this area was decreased by 50%, the average NO3-N concentrations at sites S1, S2 and S3 were reduced by about 15%; however, the average concentrations at S4 and S5 were reduced by only 1%. Furthermore, when the total effluent load from the concentrated livestock area was removed completely, the average groundwater NO3-N concentrations at S1, S2 and S3 were reduced by about 30% as compared with the original calculated results. In contrast, decreasing the area of the paddy fields in the basin did not greatly influence the groundwater NO3-N concentration. In the case of a 70% reduction in paddy field area, average NO3-N concentrations increased by about 7% at S1, S2 and S3.
| Original language | English |
|---|---|
| Pages (from-to) | 4752-4766 |
| Number of pages | 15 |
| Journal | Hydrological Processes |
| Volume | 22 |
| Issue number | 24 |
| DOIs | |
| Publication status | Published - Nov 30 2008 |
| Externally published | Yes |
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Keywords
- Effluent load control
- Livestock farming
- Modelling analysis
- Shallow aquifer
- Sound utilization of groundwater
ASJC Scopus subject areas
- Water Science and Technology
Cite this
Impacts of nutrient management and decrease in paddy field area on groundwater nitrate concentration : A case study at the Nasunogahara alluvial fan, Tochigi Prefecture, Japan. / Somura, Hiroaki; Goto, Akira; Matsui, Hiroyuki; Ali Musa, Elhassan.
In: Hydrological Processes, Vol. 22, No. 24, 30.11.2008, p. 4752-4766.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Impacts of nutrient management and decrease in paddy field area on groundwater nitrate concentration
T2 - A case study at the Nasunogahara alluvial fan, Tochigi Prefecture, Japan
AU - Somura, Hiroaki
AU - Goto, Akira
AU - Matsui, Hiroyuki
AU - Ali Musa, Elhassan
PY - 2008/11/30
Y1 - 2008/11/30
N2 - In order to help evaluate the trends in the NO3-N concentration in groundwater with a view to preventing further degradation in water quality in the future, a distributed groundwater quality model was constructed for the Nasunogahara basin. The best fit for the groundwater table elevations by the flow component of the model was achieved with average mean absolute errors (MAEs) of 0.92 m for the calibration period and 0.83 m for the validation period. Moreover, the best fit for the NO3-N concentration by the water quality component was achieved with average mean relative errors (MREs) of 29.8% for the calibration period and 30.3% for the validation period. After developing a robust model, various change scenarios were tested; specifically, the effects of effluent load control and a decrease in paddy field area on the NO3-N concentration in groundwater were predicted. The most intensively farmed area contributed about 40% of the total effluent load because of livestock farming in the basin. When the effluent load from this area was decreased by 50%, the average NO3-N concentrations at sites S1, S2 and S3 were reduced by about 15%; however, the average concentrations at S4 and S5 were reduced by only 1%. Furthermore, when the total effluent load from the concentrated livestock area was removed completely, the average groundwater NO3-N concentrations at S1, S2 and S3 were reduced by about 30% as compared with the original calculated results. In contrast, decreasing the area of the paddy fields in the basin did not greatly influence the groundwater NO3-N concentration. In the case of a 70% reduction in paddy field area, average NO3-N concentrations increased by about 7% at S1, S2 and S3.
AB - In order to help evaluate the trends in the NO3-N concentration in groundwater with a view to preventing further degradation in water quality in the future, a distributed groundwater quality model was constructed for the Nasunogahara basin. The best fit for the groundwater table elevations by the flow component of the model was achieved with average mean absolute errors (MAEs) of 0.92 m for the calibration period and 0.83 m for the validation period. Moreover, the best fit for the NO3-N concentration by the water quality component was achieved with average mean relative errors (MREs) of 29.8% for the calibration period and 30.3% for the validation period. After developing a robust model, various change scenarios were tested; specifically, the effects of effluent load control and a decrease in paddy field area on the NO3-N concentration in groundwater were predicted. The most intensively farmed area contributed about 40% of the total effluent load because of livestock farming in the basin. When the effluent load from this area was decreased by 50%, the average NO3-N concentrations at sites S1, S2 and S3 were reduced by about 15%; however, the average concentrations at S4 and S5 were reduced by only 1%. Furthermore, when the total effluent load from the concentrated livestock area was removed completely, the average groundwater NO3-N concentrations at S1, S2 and S3 were reduced by about 30% as compared with the original calculated results. In contrast, decreasing the area of the paddy fields in the basin did not greatly influence the groundwater NO3-N concentration. In the case of a 70% reduction in paddy field area, average NO3-N concentrations increased by about 7% at S1, S2 and S3.
KW - Effluent load control
KW - Livestock farming
KW - Modelling analysis
KW - Shallow aquifer
KW - Sound utilization of groundwater
UR - http://www.scopus.com/inward/record.url?scp=67650324120&partnerID=8YFLogxK
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U2 - 10.1002/hyp.7089
DO - 10.1002/hyp.7089
M3 - Article
VL - 22
SP - 4752
EP - 4766
JO - Hydrological Processes
JF - Hydrological Processes
SN - 0885-6087
IS - 24
ER -