Evaluation of regional groundwater flow by dredging the
Evaluation of regional groundwater flow by dredging the Hida River, Gero district in Gifu Prefecture Shoya KITAGAWA Course of Architecture and Civil Engineering Gifu National College of Technology
Background of the study The Hida River cannot secure Design Height Water Discharge River channel dredging Drawdown of the groundwater level was forecasted
Table of contents Introduction of the study domain ・Background of the study ・Summary of the Gero district ・Area division of the Gero district Method of analysis and analysis result ・Effect assessment of the dredging Analysis example of the Koden district Analysis example of the Mori district Summary
Hida River Gero, Gifu Basin summary of the Hida River in the Gero district
Ogawa district Shogano district Mori district Yunoshima district Koden district Area of the analysis
Method of analysis Quasi-three dimensional analysis Basic equation of the groundwater flow h: groundwater level measured on x-y plane (m) z: height of the impermeable ground(m) k: coefficient of permeability(m/s) r: water supply strength from the upper part(m/s) ①considering several set of coefficient of permeability affecting the field survey ②considering an incline of the impermeable ground
Gero-ohashi bridge Koden district
Analysis condition (Koden district) ①Incline of the impermeable ground Boundary water level Range of the analysis ②The distribution situation of the coefficient of permeability Neighborhood of the Hida River:k=14. 4× 10 -5(m/s) Flat plains:k=7. 73× 10 -5(m/s)
Distribution of the groundwater level before dredging(Koden district) The point that groundwater level is high From this direction The point that groundwater level is low Range of the analysis
Infiltration from the river to the bank inland The Hida River Distribution of contour line and current speed vector (Koden district) Range of the analysis
Down stream Gero bridge Upper stream Contour line (Gero district)
About 240 m The Hida River Influence of the dredging Distribution of the groundwater level drawdown when river water level decreased 1. 5 m Range of the analysis
Contour line, in the Koden district Comparison after/before dredging Contour line of after dredging Contour line of before dredging Range of the analysis
Contour line, in the Koden district Comparison after/before dredging Contour line after and before dredging Blue:After dredging Black:Before dredging Range of the analysis
Mori district
Analysis condition (Mori district) ① Incline of the impermeable ground Boundarywater level Range of the analysis ②The distribution situation of the coefficient of permeability Mountain area:k=3. 56× 10 -4(m/s) Flat plains:k=17. 8× 10 -4(m/s)
Distribution of the groundwater level before dredging(Mori district) Groundwater level Range of the analysis
About 300 m Range of the analysis Down stream Influence of the dredging Distribution of the groundwater level drawdown when river water level decreased 1. 5 m Upper stream
Koden district Mori district Comparison of influence of dredging About 240 m About 300 m
Summary Groundwater of the Koden district ・Infiltration from the river to the bank inland is thought about near the Gero-ohashi bridge down stream. Groundwater of the Mori district ・Groundwater flow is not complicated compared with Koden district. On the influence by dredging ・The shape of groundwater flow does not change after dredging. ・Mori district is influenced considerably by dredging compared with Koden district.
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- Slides: 21