Assess the impacts of river sand extraction
to bank erosion at Co Chien River, Vinh
Long ProvinceNgo Thanh Hau1), Huynh Trung Tin1), Trinh Cong Luan2), Bui Trong Vinh1)
1) Faculty of Geology & Petroleum Engineering – HCMUT, Vietnam2) Mientay Construction University, Vinh Long Province, Vietnam
E-mail: [email protected]
December 2013
Introduction
Methods
Discussion
Conclusion
Study areaEast sea
(Vietnam sea)
Introduction
Tien river
Hau river
85km
Method
Analysis the composition of bank material
Assessment the wave impacts
River sand activity
Figure: Taking cored soil sample
Loam and sandy of alluvial Quaternary (aQ23)
Results show that, these soft soils can easily be destroyed by any
external forces
Figure: Wind wave and wave by boat (Bui Trong Vinh, 2009)
Wave by boat
Wave impact
Bed-river sand mining provides volume of construction materials that without affect to agricultural land
Advantage:
Help to dredge to navigations
Train river
Disadvantage:
Main cause to bank erosion seriously
Affect the natural habitat and environment
River sand activity
Sand mining Sensitive area
Coordinate East NorthUTM – WGS 84 (48P)
601928 1136304602865 1136125604123 1135090604723 1134480
Coordinate East NorthUTM – WGS 84 (48P)
607805 1134885608676 1134704609565 1134923610309 1134565
Method
Using the numerical modeling MIKE 21C (DHI) to evaluate
the river bank erosion impacts from excavation of sand
The results obtained from testing were extracted by cross-
section form
Field surveyMeasure
The cumulative width (m)
Left bank Right bankCross – section VI - VI
Condition 1
•Number of facilities: 1 vessel/mine
•Capacity per vessel: 0.7m3
•Velocity: 0.14m3/min
•Operated time: 10 h/day
=> Total removed sand: 153,300 m3/yr
Modelling
SECTION IV - IVRight bankLeft bank
Left bank Right bankSECTION V - V
Initial modeling
Modeling condition 1
Elev
atio
n (m
)
The cumulative width (m)
Condition 2
•Number of facility: 3 vessels/mine
•Capacity per vessel: 0.7m3
•Velocity: 0.14m3/min
•Operated time: 10 h/day
=> Total removed sand: 459,900m3/yr
Modelling
Condition 1
Condition 2
Cumulative width (m)
Elev
atio
n (m
)
By field survey results, a number of facilities were used for sand
extraction was twice to three times as many as its affordable
which operated continuously from 12 to 14 hour per day. That
had led to increasing of quantity of extraction, changing the flow
direction and creating the local bed scours which cause of
imbalance in sand replenishment rate and serious erosion.
Discussion
River sand mining activities caused bed river change and flow change.
The overmining activities of river sand mining can directly impacted to flow direction, disturbed the bottom sediment, and damaged the balance of sediment transport of the river.
Conclusion
• Bui Trong Vinh, Ichiro Deguchi, Keiji Nakatsuji, (2008).“Beach Erosion Caused by Development in Littoral Region – Effect of Sand Extraction around River Mouth”. Proceedings of the 8th General Seminar on Environmental Science & Technology Issues, Japan, Osaka, Nov. 2008, pp. 114-119.
• Ha Xuan Chuan (2009), “Assessing the effect of dredging activities”, Journal of Science & Technology Maritime, August 2009, p14-17.
• Trinh Cong Luan (2012).“Assess the impacts of river sand extraction on bank erosion and propose the prevention methods in Tien river – Co Chien river, Vinh Long province”, Master Thesis, Ho Chi Minh City University of Technology.
• Wiebe P. de Boer et. Al. (2011). “Impact of mega-scale sand extraction on tidal dynamics in semi-enclosed basin. An idealized model study with application to the Southern North Sea”, Journal of Coastal Engineer 58, 678-689.
• Dries Van den Eyde, Alain Norro (2009). “Modeling the effect of sand extraction on the Kwintebank”, European Marine sand and gravel group, May, 2009.
Reference
THANK YOU FOR YOUR ATTENTION !
Top Related