DSpace at VNU: On the sedimentation and erosion on Huong river segment crossing over Hue city

VNU JO U R N A L OF SC IEN C E. N at , Sci , & Tech., T XIX, N01, 2003

ON T H K S E D IM E N T A T IO N A N D E R O S IO N O N H U O N G R IV E R
S E G M E N T C R O S S IN G O V E R H U E C IT Y
N g u y ê n T h a n h Son, T ran N goe A nh
D e p a r tm e n t o f H y d r o M e te o r o lo g y a n d O c e a n o lo g v
C o ile g e o f S c ie n c e , V N U
A b s t r a c t : H ue City is a vvorld c u ltu r a l tre a su re and one o f V ie tn a m 's w ell*

known tourism centers. The unstable water flow has caused erosion and
sedimentation belong to both Huong river banks, specially on the river segment
Crossing over H ue City vvhich are problem s m ust to be c o n tro lle d fo r re tu rn in g
wonderful spectacle of Hue, a small pretty city in the middle of Vietnam
Country.
The study is carried out with many difficulties in collection of hydrological data,
it seem s that up to novv. there were almost no survey vvorks on sedimentation
and erosion of tho Huong river. Thereíore ihe study results is setting up the
base of continuous studies on the progress of the river. Base on the surveyed
d a ta a n d c a lc u la tio n . the so ftw a re to tre a t and c o n tro l a ll collected data of

elevation m easurement and topographical map producũon of riverbed have been
built up. the present of sedimentation and erosion occurređ in tho Huong river
segm ent Crossing over Hue c ity and its consequences has been described
preliminarily, then withdrawn some suggestions on the main solutions for
minimizing sedimentation and erosion.

K ey w ords: S e d im e n ta tio n , e ro s io n , r iv e r b e d .

1. In tr o d u c tio n
T h e s e d im e n t a t io n and erosioiì p ro cesses h a v e long b e e n o f in t e r e s t in th(‘
field o f m o r p h o l o g y t o i n v e s t i g a t e t h e c h a n g e s of r i v e r b o d a n d b a n k e r o s i o n w i t h th o

flow

reg im e.

S t u d ie s

of

th o sc

processes

have

c o n tr ib u te d

g r ea tly

to

our

u n d e r s ta n d in g o f th e r e la t io n s h ip b e tw e e n rivor r ev olu tion p r o c c s s and w a te r flow
a s w ell a s so c io -e c o n o m ic a c t iv it ie s on th e rivcr b a sin . In r e c e n t y e a r s , m any
r e s e a r c h e s on tho m o d e llin g of s e d im e n t tra n sp o rtn tio n in th e river h a s becn

composed, and most of them focuscd on the problems in the larger river systems
su ch a s Red river or M e k o n g riv er but th er e w as verv f’(ầw o n e s ĩo c u s e d on th e rivers
in th e M id d le of V ie tn a m .
A lth o u g h m o d e llin g is now b eco m in g th e very c h e a p a n d effe ctiv e m ethod to

s tu d v an d Torecast th e hyd ro log ical p r o c esses but w e a lso n e e đ to in v e s tig a te tho
actual

situation

as

vvell a s

to

m easure

real

data

using

for calib ratio n

and

v e r iííc a tio n of th e m o d e ls , and top ograp hical da ta are n e e d c d to in p u t o f th e m odels
d u r in g r u n n in g 011.


On the s e d i n ie n ta t i o n a n d erosion on ĩ lu o n g ri v e r .

83

H u e c ity is a w orld c u ltu ra l tro asu re and one o f V ie tn a m 's w e ll k n ow tourism
c e n tre s . F o r a lo n g p e r io d , a n u n p la n n e d đ e v o lo p m e n t u n s u it a b lc la n d a n d w a tc r
US(* o f th e c a tc h m e n t a re a a n d n in n n g e m e n t o f s o c io -e c o n o m ic a c t iv it ie s h a s causecỉ
p o llu t io n

a n d đ e t r im e n t a l im p a c ts <)f’ th o c n v ir o n m e n t in

v vh ich ( le t e r io r a t io n o f

H u o n g r iv o r b c c a m e s e rio u s m a t t o r o f la n d s c a p c o f Hucĩ r i ty . T h e u n s ta b le w a te r
flo w h a s b e c n c a u s in g c ro s io n a n d s e c lim e n ta tio n b e lo n g l) o t li r iv e r b a n k s , s p e c ia llv
on th e s e g m e n t C ro s s in g o v e r H u e c it y vvhich a r c p ro b le m s m u s t to be c o n tr o lle d fo r

r e tu r n in g vvonderful s p e c t r c le o f Hue.
T h e o b je c tiv e s o f erosion a n d s c d im e n ta tio n s u r v e y on H u o n g river s e g m e n t

Crossing over Hue city are to prepare a report in which, it is needed to review and
collect d o c u m e n ts r e la te d to v a r ia b ilitv o f flow a s vvell a s e r o sio n a n d s e d im e n ta t io n
a s p e c ts on th e H u o n g river. T h en in order to get th e p ic tu re o f th e a c tu a l riverbed

conditions in th e se gm en t Crossing over Hue city, a n d access th e real State ()f
riverbank w e n è e d to build up a topographic niap o f tho s e g m e n t from V an N ie n to
Bao V inh. B a s e on t h e s e r e s u lts a n d d is c u s sio n s w e propose a p p lic a tio n te c h n iq u e s
for m in in iiz in g d e tr im o n ta l im p a c ts o f w ater flow to social e c o n o m ic a s p e c t s o f Huo
citv.

2. M a te r ia ls a n d m e t h o d s
In s tru m e n ta tio n :

A s o u n d e r F U R N O 4 3 0 0 w a s used to aid th e m e a s u r e m e n t o f w a t e r depth
from l.õ m to 3 5 0 m . T h e g e o g r a p h ic a l co-ordinate w a s c o n d u c te d a n d recorded u sin g
the GPS e q u ip m e n t G A R M IN II w ith the random error is a r o u n d 4 0 cm h o riz o n ta lly .
T he sca n n e r H P 3 2 0 0 w ith th e r e so lu tio n o f 3 0 0 dpi w a s u s e d to tr a n s fe r th e paper
graphs in to d ig ita l o n e .
P r e lim in a r y fi e ld su rv eỵs:

This is the initial survey to select the general line for im plem entation. The
mair. fe a tu r e s to be d ec id e d are:
•

Selection

•

I d e n tiíic a t io n 3 lin e s (left, right and m iđ d lc o f cross- sec tio n ) up a n d dovvn

o f m a in

obịectives a lo n g th e r i v e r f o r o b s e r v a tio n lin e s .

of the river segraent for measuring topography for longitudinal section.
•

S e le c tio n o f 100

positions fo r measuring river h o r iz o n t a l s e c tio n .

M ea su rin g m e th o d :
T he to p o g r a p h y o f th e riverbed w as p r e se n te d th r o u g h ơut th e e le v a t io n of

m a n / p o in ts vvithin t h e stu d iẹ d a r ea . T he e le v a t io n o f th e riverbed a t e a c h point
w as d e fin ed a s th e

difference betvveen th e w a te r le v e l

and

th e

vvater depth

s iin tlta n e o u s ly . U s i n g the F U R N O 4 30 0 s o u n d e r t.0 o b s e r v e th e w a te r d e p th in


84

N g u y e n T h a n h So n, T r o n Ngoe A n h

c o m b in a tio n vvith th e w a te r le v el and m e a s u r e m e n t o f p o sitio n o f th a t point
(recorded by th e G P S e q u ip m e n t).
D a ta tr e a t m e n t m e th o d :
T h e o u tp u t o f th e F Ư R N O 4 3 0 0 is th e p a p e r g r a p h p r e s e n tin g th e c h a n g in g o f
th e w a te r d e p th w it h th e d is ta n c e fro m th e s u rv e y m a r k e r ( F ig 1.1 is a n e x a m p le ).
P ir s t ly ,

th e s e

g ra p h s

w e re

scanned

in t o

th e

im a g e s

th e n

w e re

a u to m a t ic a lly

d ig itis e d a n d tre a te d b y C o m p u te r r u n n in g in P a s c a l la n g u a g e (A p p . 1) to g e t th e
a c tu a l w a te r d e p th a t each p o in t in th e lo n g it u d in a l a n d c ro s s s e c tio n a l. T h e n i t

w a s used to produce top og ra p h ical m ap o f H uong riv er bed by u s in g a m ap soítvvare.
T h e c o n to u r lin e o f to p o g r a p h ic a l m a p w e re d r a w n a t c o n to u r in t e r v a l o f 0 .5 m
le v e l on th e base m a p w it h

1 :5 0 0 0 sca le a n d a re o b ta in e d b y in t e r p o la t io n fro m

n e a re s t d e s ig n c o n to u r a n d t h e re fe re n c e c o n to u r lin e . A f t e r jo in in g a n d s m o o th in g
c o n to u r lin e s w r it e it s v a lu e s o n th e r n a p a c c o rd in g to th e d e te r n in a te d r e g u la tio n .

3. R esults and discussion
T o p o g r a p h y o f h o r i z o n t a l c r o s s - s e c tio n
T o s tu d y th e to p o g r a p h y o f H u o n g r iv e r c ro s s -s e c tio n fr o m V a n N ie n to B ao

V in h , b a se d on th e v a r i a b i l i t y o f H u o n g r iv e r bed to p o g r a p h y th e f u ll s e g m e n t w a s
d iv id e d in t o 5 s u b -s e g m e n ts w it h d iffe re n c e s in b e tl to p o g r a p h y a n d in A u e n c e to
s t a b ilit y o f flo w r a te as:
1 * F ro m V a n N ie n to 1 k m u p v v a rd X u o c D u b r id g e
2 - F r o m 1 k m u p w a r d X u o c D u b r id g e to T h ie n M u p a g o d a
3 - F ro m T h ie n M u p a g o d a to p r e - s ite o f C on H e n a re a
4 - S u b s e g m e n t p a s s in g C o n H e n a re a
5 - A f t e r C o n H e n to B a o V in h
- T h e c ro s s -s e c tio n o f th e f ir s t s u b *s e g m e n t is p a r a b o lic fo rm v v ith th e m a in
h y d r o d y n a m ic c h a n n e l is lo c a te d a t r ig h t o f th e c u r r e n t ( F ig . 1). I t is to be seem ed
t h a t e ro s io n a n d s e d im e n ta tio n

h a v e iV t o c c u rre d

a lo n g b o th

b o rd e rs as a t th o

r iv e r b e d in th e sub* s e g m e n t.
- The

second

c ro s s -s e c tio n o f th e s u b -s e g m e n t is t r i a n g u la r fo rm vvith its to p a t

th e b o tto m , w h ic h is n e a r th e le f t b o rd e r. T h e m a in h y d r o d y n a m ic flo w w a s d e c lin e d
to le ft s id e a n d a n e d d y c u r r e n t vvas fo rm e d a ls o a lo n g th e le f t s id e (F ig . 2). H e a v y
e ro s io n h a s o c c u rre đ o n th e le f t b o rd e r e s p e c ia lly in f lo o d in g a n d r a in y season. A n
a n n u a l a v e ra g e o f 5 -1 0 m o f th e b a n k vvas e ro d e d . In c o m p a r is o n w it h th e c u r r e n t o f
10 y e a rs ago, th e r iv e r s u b -s e g m e n t h a s tr a n s fe r r e d to th e l e f t sicỉe a d is ta n c e a b o u t

70* 8 0 m . A e ro d e u s u a lly vvas fo rm e d a lo n g le f t s id e a t w a t e r d e p th fro m

llm

to

19m . T h e e ro d e d s o il w a s b r o u g h t to th e o p p o s ite s id e a n d a v e r v la rg e vvater
d e p o s ite d s o il w a s ío rm e d a lo n g th e r ig h t s id e o f s u b -s e g m e n t. T h is s it u a t io n m a ke s


85

On the s e d i m e n t a t io n a n d erosion otì Huong river.

th e s u b - s e g m e n t g r a d u a lly suffered from h e a v y c u r v a tu r e an d th e river will
un dergo g r ea t c h a n g e o f current direction.
T h e d o w n s tre a m o f th e r iv e r m a y be becom e a " s ta g n a n t w a te r a re a " vvhich
w i l l cause a d e t r im e n t a l im p a c t on e n v iro n m e n t a n d la n d s c a p e o f H u e C ity.
- T h e t h i r d s u b -s e g m e n t is o b se rve d in to 15 c ro s s -s e c tio n s (F ig . 3). T h e flo w is
s te a d y . A v v a te r d e p th (Vorn 5 m to 1.0m is ĩo u n d a cro ss th e s e c tio n o f r iv e r . N o bed
e ro s io n a n d

s e d im e n ta tio n

a re

fo u n d

th e re .

B u t th e

G ia

V ie n

fix e d

dune

has

e m e r g e i a t r i g h t b o r d e r, n e a r B a ch H o b rid g e a n d b y vvh ich th e flo w r a te is a r re s te d
a n d a c c u m u la te d s e đ im e n ta tio n at th e r iv e r bed is fo u n d . T h e s u b -s e g m e n t ru n s
a cro ss H ue C i t y \v ith b o th s id e s w e re b u i lt u p w it h s to n e th u s no b o r d e r e ro s io n w as
fo u n d . 3 u t r u n o f f d is c h a rg e d fro m s m a lle r in flo v v a t th e le f t s id e o f th e r iv e r in to
t h is s e ^ m e n t, w h ic h h a s b r o u g h t also s e d im e n ta tio n m a te r ia ls . I t ca n be seem ed
c le a r ly : h a t t h e m o s t c ro s s -s e c tio n a re r a th e r f la t w it h a v e ra g e vva te r d e p th o f 4- 5
m a n d s e d im e n ta tio n vvas d is tr ib u te d on a ll a re a o f th e r iv e r b o tto m . B u t a t th e
c ro s s -s e c tio n b e fo re a n d a f t e r B a ch H o, T r a n g T ie n , P h u X u a n b rid g e , th e r e a re a
bed slope fro m le f t to r ig h t s id e vvith d e p th w a te r o f 7 -8 m . I n g e n e ra l, r iv e r b o tto n i
e ro s io n does n o t h a p p e n a n d s e d im c n t a v a ila b ilit y on t h is s e c tio n is v e ry h ig h a n d
th e m a in h v d r o d y n a m ic ílovv o c c u rre d u n c le a rly .
•

AỈ1 c ro s s -s e c tio n s o f th e f o u r th s ư b -se g m e n t is r a t h e r f la t (F ig . 4) w it h d e p th

w a te r o:‘ 3 -4 m . T h is is a n a re a h a v in g h e a v y s e d im e n ta tio n c a u se d b y th e b r a n c h in g
flo w off a n d s m a ll flo w r a te . I n a d d itio n , in d r y seaso n, th e s e g m e n t is tid e d up,

salt waier also created favourable condition for sedimentation on the river bottom.
- C ro s s -s e c tio n s o f th e la s t s u b -s e g m e n t ha s th e a v e ra g e (lo p th o f 3 -7 m a n d its
b o tto m slope r u n s lo f t to r i g h t b o rd e r vvith th e w a te r d e p th v a r ie s fro m 3 to 6- 7m .
T h is s e ^ m e n t h a s th e cro ss- s e c tio n w a s v e ry n a r r o w t h u s th e flo w r a te in c re a s e d
a n d b e ò s c o u r in g w a s o c c u rre d . A t dovvn s tre a m o f th e b e n d , th e r e is a b o u t 6 0 0 m o f
le n g th

)f th e r i g h t s id e vvas s tr o n g ly e ro d e d c a u s in g b y h y d r o d y n a m ic c h a n n e l

p a s s in g b e n d a re a . I t c a n be seen on cross- s e c tio n s in F ig . 5, F ig . 6.

T c o o g r a p h y o f l o n g i t u d i n a l s e c tio n
w * h a v e in v e s tig a t e d 3 lo n g itu d in a l s e c tio n s o f th e r iv e r s e g m e n t. T h e f i r s t is
fro m

B ỉo

V in h

to

Van

N ie n

(1 6 .2 7 .7 1 I N

and

1 0 7 .3 4 .6 6 9 E

to

1 6 .2 5 .7 3 N

and

1 0 7 .3 3 3 2 8 8 E ) a lo n g le f t s id e t h a t is f a r fro m th e b o r d e r a b o u t 2 0 -3 0 m . T h e second

s ec tio n vvas đ e c e r m in e d in th e m iddlè of the cu rren t a n d begin from V an Nien
(1 6 .2 5 .7 J 0 N a n d 1 0 7 .3 3 .2 6 4 E ) to B ao V in h (1 6 .2 9 .7 6 0 N a n d 1 0 7 .3 4 .6 4 0 E . T h e t h ir d
s e c tio n va s d e íin e d a lo n g th e r ig h t s id e fa r fro m th e s h o re a b o u t 2 0 -3 0 m fro rn Bao
V in h ( li. 2 9 . 7 4 0 N a n d 1 0 7 .3 4 .6 7 5 E ) to V a n N ie n (1 6 .2 5 .7 6 1 N a n d 1 0 7 .3 3 .6 2 0 E ). H he
r e s u lts ro m t h e w a tẽ r c ie p th rn e a s u re đ lin e on th e lo n g it u d in a l s e c tio n h a v e s h o w n
t h a t d if e r e n t s e d im e n ta tio n a n d ero si on level w ere o c c ư rre d in th e dr y er

segm en t.


86

N g u y en T h a n h S o n , Tran Ngoe A nh

500

200

300

400

500

Fig. 1. Typical cross-section of th e íìrst sub- Fig. 2. T ypical cross-section of the second
segm ent

su b s e g m e n t

400

500

Fig.3. Typical cross-section of the third sub-

Fig.4 T ypical cross-section of the íourth

segm ent

su b s e g m e n t

500

500

Fig.5 Typical cross-section of the last sub-

Fig.6 Typical cross-section of th e la s t sul)

segm ent

segm ent

On th e b a s e o f 3 lo n g itu d in a l se c tio n s and froiiì d ep th m e a s u r in g d a ta , som e
r e m a r k s of to p o g ra p h ic a l c h a n g e s could be p r e se n te d a s follows:
• S c c tio n from V an N ic n to Xuoc Du B ridge. T h e bed to p o g ra p h y d o e s not
c h a n g e a c c id e n ta lly on th e 3 v e r tic a l c r o ss-se c tio n s. T h e d ep th o f riv er v a r ie s from 3
to 6m vvith th e d e e p e s t r u n n e l in th e m iddle. It vvas found a t th e b otto m s o m e sh ort
s a n d w a ve.
• S e c tio n from X uoc Du bridge to T h ie n Mu pagod a. It is th e m o s t typical

eroded section of th e se gm ent. For exam ple a t lcft side t h e r e is an unstnblo


0 /1

//ỉ
a n d crosion 0/1 H u on g river.

87

lo n g itu d in a l s ec tio n , tho vvater from 5 to 8m and a t Xuoc Du brid g e up to 17m. It is s h o w ed th a t s c o u rin g p r o c ess is
h a p p e n in g and w ill be c o n tin u e a t ser io u s lcvel. Tho bed top ograp hy is rough a lo n g

tho r i g h t side a n d the middle of vertical cross-sections. So, th e left side of th e river
s e c tio n m u s t be paid m a n y a t t c n tio n of in v e s tig a tio n in d e ta il to find out th e b e s t
s o lu tio n s .
- S e c tio n from T h ie n Mu pagoda to Con H en. T h e longitucỉinal s e c tio n varies
v vith th e d e p tlì fro m

4 to

I m . H o w e v e r, th e r e a re a n im m e rg e d d u n e a t b o tto m

before B ach Ho brid ge and a big d u ne im m e r s in g betvveen P h u X u a n a n d T r a n g
T ien B r id g e and do not find o u t th e m ain h y d ro d y n a m ic c h a n n e l of th e cu rren t.
- S e c tio n p á s s in g C o n H e n a r c a . 3 lo n g it u d in a l s e c tio n s o f C on H e n a re a a re

s im ila r . T h e shallcnv w a te r depth o f 2-3m is m uch low er th a n th a t of up an d dovvn
river s e c tio n . ỉt is proved th a t th e section h a v in g th e ĩa v o u r a b le c o n d it io n s for
s e d im e n ta t io n . It can be found th a t íầctors c a u s in g s e d in ie n ta t io n w e re a c te d in th e
s a m e ty p e and spreadecỉ over th e river bed sectio n .
- S e c tio n a fte r Con Hen to B ao Vinh. T op og ra p h y o f longitudinal s e c tio n v a r ie s
w ith w a te r depth

ÍVoni 5 to l l m

and th e bottorn slo p e to tho dovvn s tr e a m .

H yd ro d y n a m ic c h a n n e l is in th e m id d le of th e cu rren t. T h e vert ical c r o s s -s e c tio n of
r ig h t s id e is u n s ta b le d u e to l i t t l e e ro s io n h a s o c c u rre d a lo n g t he side.

B o t to m to p o g r a p h y

A ccordin g to H u o n g R iver bottom top ograp h ical m ap w ith sca le 1:5000 th e r e
a re a b o u t 70% o f th e r iv e r bed a re a fro m V a n N ie n to B ao - V in h a t a n e le v a t io n o f

3-5m vvater depth. T h e m a x im u m depth is 19.8m a t th e cro ss-se c tio n M C 19 (near

Xuoc Du bridge). Gencrally in the studicd river area, the deposition of sediment was
d o m in a n t. It could be d iv id e d into 4 a r e a s for th is river s e g m e n t.
T h e first is from V an N ie n to lk m up w ard Xuoc Du bridge. T ho bottom
top ograp hical m ap s h o w e d th a t tho riverbed is s te a d y . T h e w a tc r lin e o f m a x im u m
depth is d is tr ib u te d n e a r the m id d le of th e current. Tho gcological fo u n d a tio n o f
th is sectio n is q u ite d u rab le. T h ereío re, th ere are h ig h s t a b ili t y o f flow rate.
T he second is from lk m u p w a rd Xuoc Du bridge to T h ie n Mu pagod a. It is th e
d e e p e st a rea and its b o ttom top ograp hy g r ea tlv sp e c ia lly in th e c u r v a tu r e s ec tio n
n ear Xuoc Du bridge. (before Xuoc Du bridge 1.5 kin an d b c h in d 1 km). T h e bottom
topography of th e a r ea v a r ie s from 2.9 to 19m. T h e r c fo r è t the h y d r o d y n a m ic
c h a n n cl g o es to th e le ft s id e and c a u s e h e a v y ero sion a t th e s id e vvith d is t a n c e o f
more than 2km . Eroded soil w a s brough t to th e o p p o site s id e and a v e r y la r g e
a lluvial ground w a s form ed a lo n g th e right s id e w hich h a s c a u s e d th e c h a n g e o f

direction current of this river segment. A erođed gully was formed along the left
side at w a te r depth from 11 to 19m. It can be seen t h a t the c u rr e n t of th is se g m e n t
h a s tr a n s íẹ r r e d to th e h»ft s id o a b o u t 7 0 -8 0 m w h e n c o n ip a r in g w ith to p o g r a p h ic a l


N g u y en T h a n h So n, T r a n Ngoe A n h

88

m a p e s ta b lis h e d in 1986. T h e s e c tio n a lo n g T h ie n M u pagocỉa a re a is in í lu e ic e d b y
m o u n ta in s s v s te m a t le f t s id e o f th e r iv e r , so t h a t th e h y d r o d y n a m ic c h a n n e l h a s
g o n e to le f t s id e a n d th e r e a re a ls o a r u n n e l a t r iv e r b o tto m w it h d e p th u p to 8 .Ồm.
F ro m t h e r e to th e dovvn s tre a m o f t h is s e c tio n th e r iv e r flo w is m o re a r d m o re
s te a d y .
T h e t h ir d is fro m T h ie n M u p a g o d a to Con H e n a re a . T h e b o t t o m to p * g r a p h y
o f th e s e c tio n is q u ite f la t . M o s t b o tto m to p o g r a p h y h a s e le v a tio n d iffe r e n c e ) f 2 -4 m .

W it h th e le n g th o f 5 0 0 m b e fo re G ia V ie n d u n e , th e d iffe re n c e o f b o t t o m to p > g ra p h y
is fr o m 2 -3 m , w h ic h is e a sy to c re a te A o a tin g d u n e in d r y sea so n . A t le f t s de n e a r
B a c h H o b r id g e h a s a r u n n e l v v ith d e p th o f õ to 7m . H o vve ve r, a s m a ll s a n d dane h a s
b e e n e s ta b lis h e d a n d is r u n n in g g r a d u a lly to th e N o r t h . S e d im e n ta tio n alsc fo rm e d
in a re a s u r r o u n d in g P h u X u a n b rid g e . 11 c re a te d im m e rg e d d u n e a t th e b o tto m
v v ith s iz e as la rg e as G ia v ie n d u n e . In g e n e ra l, t h is a re a n e e d s s c ra p e fo r : r e a tin g
th e h y d r o d y n a m ic c o r r id o r w h ic h is n e c e s s a ry f o r p r o te c tio n o f s e d im e n ta ù o n a n d
m a in t a in in g s t a b ilit y o f th e f lo w ra te , fo r p u s h in g u p e ro d e d m a t e r ia l at b o tto m
r iv e r to th e d o w n s tre a m a n d m a in t a in in g th e n a v ig a t io n c h a n n e l f o r sh ip s a n d
o th e r s o c io -e c o n o m ic a l a c t iv it ie s on th e r iv e r in d r y season.
T h e a re a fro m

C o n H e n to B ao V in h ha s a to p o g r a p h ic a l d iffe r e n c e o f th e

b o tto rn w h ic h f lu c t u a t e betvveen 4 .5 a n d 8 m o f vva te r d e p th . B e c a u s e oí n a r r o w
h o r iz o n t a l c ro s s -s e c tio n in t h is c u r v a t u r e s e c tio n th e fio w ra te is in c re a s e d a n d th e
r iv e r b o tto m w a s e ro d e d . 'T h e h v d r o d y n a m ic c h a n n e l in th e m id d le o f th e c u r r e n t
a n d flo w r a te is q u ite s te a d y .

S o m e m a ỉn

s o lu ti o n s to m i n i m i z e s e d im e n ta t io n

a n d e r o s io n

o f th e r iu e r

segm ent
H u o n g r iv e r h a s r e la te d w it h H u e o ld c it y d u r in g it s d e v o lo p in e n t p e rio d . T h e
p r o te c tio n o f H u o n g r iv e r is a ls o th e p r o te c tio n o f H u e c it y , so t h a t i t is e s s e n tia l to

d e v e lo p

e ffe c tiv e

p ra c tic e s

in

o rd e r

to

p re v e n t

and

o v e rc o m e

e n v iro n m e n ta l

c o n se q u e n ce s. In te g r a te d p ra c tic e s o f a l l a s p e c ts su c h as Science a n d te c h n o lo g y

management options, environmental e d u c a tio n are necessary Ểor solving this
p ro b le m . In t h is r e p o r t, som e m a in s o lu tio n s vvere p ro p o s e d to s o lv e s e d im e n ta tio n
a n d e ro s io n in th e s t u d y in g r iv e r s e g m e n t, su ch as:
-

R e b u ild in g th e flow d ir e c tio n o f c u r v a tu r e s e c tio n a t X u o c D u b rid g e for

r o h a b ilit a t in g s te a d y

State o f th e c u r r e n t h y b u ild in g s to n e s p u r s y s te m s a t th e le f t

s id e o f th e r iv e r a t th e s ite o f 2 -3 k m b e íb re X u o c D u b r id g e . I t is n«ecessary to b u ild
s to n e s p u r s y s te m s w it h th e s p u r le n g th o f 30- 4 0 m a n d s e p a r a tin g each o th e r a b o u t
5 0 -7 0 rn . T h e s p u r m u s t be h ig h e n o u g h to p r e v e n t w a te r le a v in g 0 'f H u o n g r iv e r in
th e flo o d in g seaso n. T h e s to n e s p u r s y s te m s m a in ta in th e s te a d y flc-w fo r p r e v e n tin g
a c o m p le te c h a n g e o f c u r r e n t d ir e c tio n vvhich m a y ca u se H u o n g r i v e r d ow n s tre a m
b e c o m in g "a s ta g n a n t w a te r a re a ".


89

On the s e d i m e n t a t i o n a n d erosion on Hĩiong river.

- S t r e n g c h e n in g scrape off tho rivcr bed in th e arca from Gia V ien to Con Hen
fo r c r e a tin g a g r e a t h y d r o d y n a m ic c o r r iđ o r a n d m a in t a in in g a h ig h flo w

ra te fo r

s c o u rin g s te p b y s te p s e d im e n ta tio n a t th e r iv e r b e d a re a . G e n e ra l s c ra p e n e e d s to
be done in s h o r t tim e a n d s u p p le m e n ta r v s c ra p e is n e c e s s a ry fo r

S 0 Ỉ1 1 0

y e a rs .

- C a r e ĩ u l n ia n a g e m e n t o f e n g in e e rin g w o rk s o f s a lt y p r e v e n tio n fr o m

tid e

p r o p a g a tin g t o C o n H e n a re a w h ic h c a u s e d h e a v y s e d im e n ta tio n a t r iv e r b o tto m o f
th o se ctio n .
- C o n s o lid a tin g

íb re s t

eco syste m

in

u p s tr e a m

a re a

fo r

r e g u la t in g

w a te r

a v a ila b ilit y o f th e c a tc h m e n t a n d flo w r a te in th e flo o d in g seaso n, in c r e a s in g w a te r
H o ld in g c a p a c ity in th e s o il a n d c o n tro l s u rfa c e e ro s io n o f th e slo p e a re a .

References
1.

F in c l R e p o r t o f P r o ịe c t K C -1 2 , M in i s t r y o f W a te r R e s o u rc e .

2.

N g u ỵ e n T r o n g H ie u , D a ta s e ts a n d c l im a to lo g i c a l a t l a s o f V ie tn a m ,

P ro je c t

42 A 0 1 .0 1 . H y d ro -M e te o rơ lo g ic a l S e rv ic e o f V ie tn a m
TAP CHỈ KHOA H Ọ C ĐHQ GHN. KHTN & CN, T XIX, No1 ,2 0 0 3 _________

VỂ BỔI, XÓI ĐOẠN SÒNG HƯƠNG CHẢY QUA THÀNH PHỐ H ư Ế
VÀ CÁC GIẢI PH Á P GIẢM THIÊU
N g u y ễn T hanh Sơn, T rần N gọc A nh

Khoa Khí tượng Thủy văn & Hải dương học
Đại học Khoa học Tự nhiên, ĐHQG Hà Nội
Huè là m ộ t th à n h phô'du lịch và là di sả n v ăn hoá t h ế giới đã được U N E S C O
công nhện. S ô n g H ư ơ n g là m ộ t c ả n h q u a n q u a n tr ọ n g củ a H u ế , h iệ n n a y đ a n g b ị s u y
th o á i trể m t r ọ n g do t ì n h t r ạ n g b ổ i xói lò n g sông. N g h iê n cứu b ồ i, xó i và tìm ra các
g iả i p h á ĩ g iả m th iể u là m ộ t n h iệ m v ụ c ấ p b á ch n h ằ m bảo vệ th à n h phô và các c ả n h
q u a n m ô tr ư ờ n g của nó.

Dựi t r ê n các k ế t quả k h ả o sá t lòng sông H ương b ằ n g m áy đo sâ u hồi âm
F Ư R N O 1300, đ o ạ n c h ả y q u a th à n h H u ế từ V ạ n N iê n đ ế n B ao V in h , các tá c g iả đã
th ự c h iệ i được m ô t sô" n ộ i d u n g sau:
- X iy d ự n g p h ầ n m ềm xử lý tín h to á n sô liệ u k h ả o s á t, lậ p b ìn h đồ đ o ạ n sô n g
tỷ lệ 1: 5 )0 0 p h ụ c v ụ c ô n g tá c q u y h o ạ ch th u ỷ lợ i, g ia o th ô n g và các lĩ n h vự c k in h tê
quốc dâr k h á c .
- Mô tả c á c đ o ạ n sô n g có h iệ n tư ợ n g b ồ i, x ó i đ ặ c b iệ t n g u y h iể m và đề x u â 't m ộ t
sô g iả i p iá p n h ằ m h ạ n ch ế c h ú n g .