KHOA HQC
^/PHAN T I C H B I E N DONG LONG DAN SONG CHU QUA TAI LIEU DO DAC VA ANH VlfiN THAM
Nguyin Thi T h u H u y i n , PGS.TS Nguyen T h a n h Himg, Vu Dinh Cirffng Phong Thi nghiem Trong diem quoc gia ve Dong luc hoc song bien Pham Quang Son Vien Han lam Khoa hoc Cong nghe Viet Nam
Tom tat: Trong nhiing ndm gdn ddy. virng hg luu song Chu phdi ddi mat vai tinh trang ldng ddn bi biin dong mgnh. Ben egnh su biin dong long ddn theo quy lugt tucmg tde thuy thgch dong lire tu nhien cm ddng song, long ddn song Chu con bi bien dong do tde dgng cua con nguai tren dong chinh nhu xdy dung ho chira thuang nguon dieu tiet dong chdy, khai thdc cdt long song.
Bdi bdo gidi thieu mot s6 kit qud nghien cuu qud trinh bien dong ldng ddn song Chu dogn tir hg luu hd Cua Dgt din ngd ba Gidng thong qua so lieu do dgc thuc te vd dnh vien thdm.
Tie khoa: song Ciiu, diin biin long dan, sat Id b& song, tac dong ho ch^;
Summary; In recent years, Chu river, downstream of Cua Dat reservoir (Thanh Hoa province), has faced with river bed change severely. Beside of the river change due to hydrodynamics and sediment transport naturally, the river morphology has been changed due to impact of human activities on the main river, as building reservoir, and sand mining. This paper presents some initial results in analysing the river morphology from downstream of Cua Dat reservoir to the Giang bifurcation based on measurements data of topographic, geological data and remote sensing.
Keyword: Chu river, river evolution, river bank erosion, impact of reservoir.
I. D ^ T VAN DE tang da g6c nam sau; khu vyc tir CUa Dat L l T6ng quan v i khu vifc nghien cihi ^ ! " ^ ^ ' Thugng n i n dia chat long song chu , , yeu la bim set, cuoi soi lan cat mau; va khu Song Chu la phu luu Ion nhat cua he thong ^^^ ^^ g a i Thuang d t o nhap luu v6i song song m. Song Chu da, 325km, phan chiy vao ^^ j ^ ; „ g j ^a Giang n i n dia chdt long s6ng Viet Nam dai 160km, qua cac huyen Que ^y^^ . „ ^ ^^^j ^-^ j . , ^^.. ^ . ^4, ^^^ 1,^
t ' ' ? ^ . . ^ ? ' . . ' ^ ' • ^ " ™ 8 ^ " ™ ' ™ ' va bun set pha [4]. Trong nhiSu nam gin Auan (Thanh Hoa) v^ nhap lim vol sons Ma >~ 1 1 . ' L - L-* A . - J * *- i.- *- j . . . , . „ . , ' , . ... • ' , . . „ , ^ day, khi h?iu bien doi dan den ehe dp dong tai nga ba Giang. Vol dieu ki6n dia chat p h t o 1.- - •.•' ..*• •- >•» . • ' . . • i.»
. u - ^ • lu - . , , • " • " " " " t " " " ' chay cung bien doi, vi?c dieu ti6t c i a cac ho thanh cac kbu wrc ro ret: khu vuc tit thuong u- .u * T I . XT r . . T^ . /1.1 5 - r... \.- : „ . ' " , ' " v ' l B chua thucmg nguon Hua Na, Ciia Dat (ho nguon song Chu den cua Dat phan bd nham r.- n . i.k.A- - 1. • i. - ^nAo^ J- 1 - , , , . _ . , , , . J , . Cua Dat bat dau van hanh nam 2009) da lam thach trong cac doain nay chu yeu la tr&n tich . 1 . 1 . . u-» j ' L* *- j . •..
, . , - . , . . " " " " ' " - " anh huong nhieu den ehe do done chay song luc nguyen macma xen ke da voi; khu vuc tit r.t. T I , - • ... i- • ' . . : . . . r.- n . j» n-- TV . , .1 , .•,,"* Chu. Them vao do la cac host d6ng xay Cua D^t den Bai Thugmg co nhieu bai boi, j .: . . 1 . - i . •- . i . . . .
khai thac ngudn n u a c , khai thac cat a cac bai N ^ ^ X ^ i f - S T ' " ^ ' " ' " " ' " ^ ^^^-^^ f ^ f l ^ b i l n dm d6ng chiy Ngay thong qua phan bi«a: 24/9/2014 "l ""=" "^^ ^^f ' " . ' " 8 t"™ <=« dan den long Ngay duy?t dSng: 24/4/2015 dan ha du bi bien doi cing ngay nhieu.
8 TAP CHl KHOA HpC VA CONG NGHE THUY Lpi S(3 26 - 2015
KHOA HOC ^ E S H J B I I ^ B
Mgt trong nhung bieu hien cu the ciia s\r bien doi binh thai doan song Chu la hien tugng xoi lo bo song 6 ha luu ho Ciia Dat, nhieu vi tri dgc tuyen song Chu bi sat 16 nghiem trgng.
Nguyen nhan so bg xae dinh la do mgt lugng Ion bun dugc giii lgi tai cac h6 chiia gay ra mdt
can bang bun cat a ha du, ciing voi cac tac dgng cua con ngucri din dong chay va long dan. De tim giai phap 6n dinh cho he thong de dieu ciing nhu cac cong trinh tren song nghien cuu nay phan tich bien dgng long dSn song Chu qua cac giai dogn tit so lieu do dgc.
Hinh 1: Sgt Id mdi de td song Chu tai xd Thieu Vu nam 2012
Hinh 2. Vi tri mat cdt do dia hinh, ho khoan dia chdt vd trgm khdo sdt do thdy vdn tren
dogn song nghien cuu IL PHU'ONG PHAP NGHIEN CUtJ
Phan tich hien trgng va xae djnh bien dgng long dan song Chu tU s6 liSu thuc do la mgt van de phiic tap vi doi hoi nhieu s6 li^u trong qua khii, da dang ve loai so lieu nhu so lifu ve thuy van, so lieu ve dia hinh long dan, hinh thai mat bang va s6 lieu dia chat. Do do can co each tiep egn va phuang phap nghiSn ciiu khac nhau. Trong nghien cuu nay da ket hgp cac phuong phap:
- Phuong phap tong hgp, thong ke s6 lieu dia hinh, thiiy van, dia chat thu thgp dugc.
- Phuong phap phan tich tai li?u lich sir: cac tai li?u ve dja hinh, dia chat, thuy van dugc so sinh, phan tich danh gia bi§n d6ng qua cac th6i ky khac nhau.
- Phuong phap vien tham va GIS: pbSn tich anh vien tham chyp khu vyc nghien ciiu qua cic thai diem lich su de danh gia biln dgng
long dan tren mat bang.
III. KET QUA VA THAO L U ^ 3.1 Bien dgng long dan gSy s^t \6f bo* song va cdng trinh de dieu
Ket qua dieu tra thu thgp so lieu cho thdy tren tuyen song Chu trong nhiing nam gan day co mgt so trgng diem xoi lo long song gay sat 16 bo song anh hu6ng nghiem trgng d6n an toan de dieu, lam hu hai (gay sgt chan ke hoac sat trugt mai de) cac cong trinh ke bao ve eac vj tri sat 16 chu yeu nam ve phia bo de ta song Chu (Bang 1).
Tu bang so lieu co the nhan thay, cac vi tri sgt 16 hau bet la tai cac vi tri s6ng cong, dong chay CO luu toe lan ap sat bo vao miia lii, cac vi tri sat 16 da dugc ke bao ve va on djnh trong . giai dogn 2006 - 2012. Tuy nhien, den nam 2013 rat nhieu diem sgt 16 da xuat hien tgi cac diem xung yeu nay.
TAP CH( KHOA HOC VA C O N G N G H £ T H O Y LOI S 6 26 - 2015
KHOAHOC " ^ E g B Z B S M
Bang 1: Vi tri cac dilm s?t l* nghilm frjng d9c tnyin sSng Chu TT
1 2 3 4 5 6 7
Bia danh Do?n ke xa Tho Minh
Dogn ke Mau Xanh De, ke Van LO -Bat Cang, xa Thp NguySn D6, ke Cang Ha, xa Tho Truong - xa Thieu Ngoc Doan de, ke Thieu Vu Doan de, ke Thieu Tien Doan d6, ke thuoe xa Thi?u Tam
Vi tri theo Km dS K3,120-K3,320 taChu K13+101- K13+300taChu K24,142-K25,226 huu Chu K18,926-K20,2 taChu K24 - K25 ta Chu K27,5 - K28,5 taChu K38,0-K38,3 huu Chu
TG xay ra svco 2003-2005, 2013 2003-2005, 2013 1996, 2003- 2005,2013 2003-2005, 2013 2013 2013 2003-2005, 2013
MuT d$ thift hai Bi sat 16 cue bo timg mang, vach diing Bi silt hSng chan, mdi k^
bi 16c la
Sat tru<;rt mai dS phia song, bai phia thuong luu ke Sat la
Sat la Sat lot
Sat ba sat chan de Nguon: Chi cue Be dieu vd PCLB Thanh Hoa, 2013
3.2 Bien d^ng long dan sdng Chu qua tai li^u dia hinh
Tai lieu dja hinh long song Chu thu thap dupc cho nghien cuu g6m tai lifu mat cit ngang song dupc do dae trong cac nam 1999, 2008, 2011- 2014. Qua phan tich s6 lieu nhi8u nam cho thiy:
- Duimg ljch sau co sir bi6n dii dang kS, nhiing nam gan day cao dp day song co xu thS ha thjp ddn (Hinh 3), dae bi$t la doan each djip Cua Dat khoang 10km long song bj hg thap xu6ng gjn 6 m {nam 2008 so voi nam 1999). Trong giai doan 2011-2014, cao dp day song doan tir sau dap Bai Thupng djn nga ba Giang co sir bijn dpng Ian, tai khu v\rc each dap Bai Thuang 15km vi ha luu day song bi xoi sau xu6ng khoang 7m so vai nam 1999, khu w e gin nga ba Giang xoi sau khoang gin 5m.
Hinh 3. Dien bien cao do lach sdu doc song Chu tir sau ho Cita Bgt den ngd ba Giang - Mgt cgt nggng; Chieu r0ng mgt cit ngang tgi cac vi tri so sanh bien d6i khong nhiSu, chenh lech trung binh la 89 m, lan nhit la 159m (tgi mat cit SCHU47). Doi voi cao trinh day song tai cac vi tri qua cac nam co su biln d6i co nam long s6ng duoc boi len, co nam bi xoi di.
Mire dp ha thip mat cit tren tuySn song Chu tir mat cit SCH30 dto mat cit SCH52 Ion nhit la
TAP CHl KHOA HOC VA CONG NGHE T H C I Y LOI S 6 26 - 2015
KHOA HOC 5.42 m tai mgt cit SCH32 va it nhit la 0.16 tai
mat cit SCH41. Mot s6 mgt cit nhu SCHU36, SCH37, SCH41 va s6ng Chu SCH52 co sir biSn ddi manh: mat cit SCH36 long song ha thip lien tilc tir cao dp 2.89 m xu6ng 1.98 m, trung bmh han 0.45 m/nam; mat cit SCHU37 dap dpng Ion nhit la 2.1m, tir cao dp 4.01 m
xudng 1.90 m; mat cit SCHU52 toan bp lpng song hi ha thap, nhieu nhat la 7.6m, tit cao dp 1.08 m xuong -6.58 m. Vcri su ha thap long song nhu tren co the la mot trong nhiing nguyen nhan din din sat lof bo song xay ra a nhiSu vi tri dpe song Chu (Bang 2 va Hinh 4).
Bang 2. Bien doi cao d§ day va chieu rong long chinh trgn m^t cit ngang song Chu Vitri
Ten mat cat
SC30 SC32 SC33 SC34 SC35 SC36 SC37 SC38 SC41 SC42 SC45 SC46 SC47 SC48 SC49 SC50 SC51 SC52
KCtii Cua B^t (m)
29359 34310 35866 37983 40264 42180 44230 45852 51188 53440 58924 60608 62319 63894 64908 66753 69330 72977
Cao do day thap nhat (m)
N a m 200S
3.24 -5.50 1.09 1.66 0.94 2.09 0.61 -0.69 0.39 -1.34 -1.65 -3.90 -1.81 -3.89 -5.44 -1.60 -5.19 -3.74
Nam 2011
4.22 -0.08
1.6 2.56 -0.33 2.66 0.93 0.61 0.52 -0.61 -0.96 -1.92 -2.13 -5.01 -5.68 -4.93 -4.83 -4.1
N a m 2012
4.4 -0.09 1.48 2.33 -0.51 2.97 2.04 1.23 0.39 0.58 -1.22 -1.19 -2.71 -4.85 -3.86 -4.3 -5.42 -3.39
N a m 2013
3.4 -3.14 4.73 3.36 -1.02
1.63 0.9 0.6 0.55 0.69 -1.04 -2.76 -3.48 -3.82 -5.3 -4.77 -6.52 -6.58
C h S n h lech
Idu nhat 1.17 5.42 3.64 1.7 1.96 1.34 1.43 1.92 0.16 2.03 0.69 2.71 1.67 1.19 1.82 3.33 1.69 3.19
Chieu rdng long chinh (m)
N a m 2008
379 358 333 652 355 399 275 352 387 323 310 226 276 241 187 235 247 423
N a m 2011
351 356 346 542 394 409 376 397 322 410 195 224 219 184 237 226 300 393
N a m 2012
380 353 263 653 510 399 410 304 325 327 311 226 307 266 236 235 318 403
N a m 2013
349 334 346 657 354 351 410 315 431 279 311 229 378 218 214 348 296 502
Chenh lenh
lorn nhat 31 24 83 115 155 58 135 92 109 131 116 5
159 82 50 122 71 110
TAP C H l KHOA HOC VA CONG NGHE T H O Y LOI S f l 26 - 2015 11
KHOA HOC
DItN BrtN MiT CAT NGAKG SANC c m ' IAI ^1 T M SI4T CAT
Hinh 4. Dien bien mdt sd mgt cit ngang trin song Chu 3.3 Phan tich bieu d$ng long dau sdng Chu
qua tM lifu anh vien thdm
Nghien ciiu da phan tich dien bidn vi tri duang b6 dogn sdng Chu tii sau ho Cira Dat tdi nga ba Giang qua cac thdi diem (date) anh ve tinh
Bang 3. Bien doi chieu r$ng Idng chinh sdng Chu tren anh vien thdm Landsat (MSS, TM, ETM, OLI) va ban do dia hinh UTM cac nam tit 1965 ddn 2013 (Hinh 5). Cac anh sft dung c6 dd phan giai khdng gian tir 15m ddn 30m, dupe xir ly tren he thdng phin mdm PCI-Geomatica 9.1 [3].
Vi tri theo mat cat
MC29 MC30 MC31 MC32 MC33 MC34 MC35 MC36 MC37 MC38 MC39 MC40 MC41 MC42 MC43 MC44
Be rdng Idng chinh (m) Nam 196S
135 224.5 264.4 130 154.4
180 250 170 41 140 69.5 126.8
100 119.4 109.4 110
Nam 1975 176.7 111.2 213.5 157.3 206 250 200 130 172 175.3 147.8 184 135 156.4
119 120
Nam 1990 137.9 190.5 233.9 96 120 130 300 170 170 125.3
126 193 108.2
114 146.3
130
Nam 2001 140 165.3 157.1 141 130 160 190 270 87.1 117.8 153.7 200 92.8 180 143.9 130.3
Nam 2013 158.7 224.4 168.6 203
150 390 200 270 260 234 207.5
240 170 228.5 169.5 230.5
Ghi chii
12 TAP CHl KHOA HOC VA CONG NGHE THUY LOI S 6 26 - 2015
I KHOAHOC ^ E M B M
Vi tri theo mat c9t
MC45 MC46 MC47 MC48 MC49 MC50 MC51 MC52
Be rong long chinh (m) Nam 1965
100.7 120 142.5 159.5 126.1 194 109.6
420
NSm 1975 165.4
162 123.8
170 163 198.3 169.2 580
Nam 1990 146.3 161.2 161 151.4 173.2 192.6 126 320
Nam 2001 151.2 154.1 185.1 180 155.7 157.2 125.9 330
Ndm 2013 203 219.6
205 152.3 162.7 272.4 252.5 480
Ghi chu
Qua phan tich mat bang mgt so nam cy the 1965, 1975, 1990, 2001 va 2013 tai mgt s6 vi tri nghien cirn cho thay be r^ng long chinh co su bien doi lan co dogn song dugc m6 rgng ra CO dogn song bj thu hep di, chenh lech 16n nhat
la 260 m va be nhat la 28,6 m va trung binh la 116.7 m . Mgt so bai dugc hinh thanh hoac mat di nhu tgi m^t cat SCH35 (nam 1990), SCH36 (nam 1965), SCH37 (nam 2013).
Hinh 5. Bien dong long ddn song Chu tir mat cdt SCH35 den SCH37 qua dnh vien thdm Qua phan tich cho thay, trong 48 nam qua
(1965-2013) long din song Chu bi^n dgng manh theo chieu ngang trong khong gian nam giua hai tuyin de ta-de hihi. Mgt so vi tri co su biln dgng 16ng din mgnh nhu: dogn nga ba song Am - song Chu, dogn Xuan Hoa - Tgo Lap, dogn Xuan Yen - TT. Thg Xuan, dogn
Thieu Phuc. Dae biet tren doan song nay co nhilu dinh cong, co ban kinh cong (R) thay doi rdt Ion tij 350m din 1.800m; nhu cac dinh cong: Xudn Thien Thg Dien (R=1.670m):
dinh cong Tao Lap - Xuan Hoa (R=1.270m):
dinh cong Xuan Tan - Xuan Thanh (R=750m):
dinh eong Thieu Vu - Thieu Toan (R=780m),
TAP CHf KHOA HOC VA C O N G N G H E T H O Y LOI S6 26 - 2015 13
I KHOAHOC ^ E C B S ^
dinh cong Thieu Chau Thieu Nguyen cung trung vai nhiing noi long din biSn dang (R^950m), dinh cong Thieu Hgp - Thieu Tan va phat triln manh cua cac dinh cong tren (R=830m)... Nhung dilm ba song bi sgt 16 dong song Chu.
mgnh dugc ghi nhgn trong nhiing nam vira qua
Hinh 6. Bien dgng long ddn sdng Chu qua tu lieu dnh vien thdm (giai dogn 1965-2013) 3.4 Cdc yeu to chinh anh hv6ng den qua mua can tu thang XI-VI rmm sau. Ba thang co trinh bien dpng long dan song Chu
+ Anh hudng cuayeu td thiiy van, thiy luc, bun cdt:
- Yeu to thuy van, thiiy luc:
Mua lii tren song Chu keo dai tir thang VII-X, chiem 63%-73% tong lugng dong chay ciia nam.
dong chay lan nhat la cac thang VII-IX chiem 52-60% lugng dong chay ca nam. Thang co lugng dong chay Ion nhit la thang IX, chiem tir 20-24% t6ng lugng dong chay ca nam.
Phan ph6i dong chay trung binh thang trong nam cua mgt s6 tram song Chu nhu sau:
14 TAP CHl KHOA HOC VA C O N G NGHfi T H O Y L d l S6 26 - 2015
I KHOAHOC ^ A I J M J M ! ! ^
Bang 4. Dong chay trung binh cac thang tai mot so tram tren s6ng (m^/s) Tram
Cua Dat Mudng Hinh Xuan Khanh
1 55.1 41.8 32.5
II 44.5 33.6 19.1
111 40.4 28.8 13.6
IV 43 29.5 17
V 76.3 40.2 51.8
VI 124 80.9 124
VII 156 114 156
VIII 233 189 296
IX 292 237 471
X 262 162 286
XI 126 89.5 155
XII 72.6 57.1 60.3
TB 128 92.1 140 Su phan bo dong chay nam tren luu virc phu
thugc vao phan bo mua va cac nhan t6 mat dem, dia ehat, tho nhuong eua luu vuc. Vimg thugng nguon song Chu lugng dong chay tuong d6i nho, sau khi qua bien giai Viet Lao, lugng dong chay tang dang ke. Tit Muang Hinh den Bai Thugng do dia hinh thuan lgi.
luu lugng dong chay tang, tgi Cua Dat Mo=20.51/s.km^.
Dong chay kiet chilm 26% ting lugng dong chay nam, keo dai 8 thang tij thang XI-VI. Ty le phan phoi tnmg binh lugng dong chay cac thang mua can so voi dong chay nam tai mgt so trgm thiiy van tren song Chu nhu bang 5:
Bang 5. Ty If dong chay kiet tai mot so tram Iiru virc song Chu (%) Tram
Muang Hinh Cita Dat Xuan Khanh
XU 5 5 4
I 4 4 2
II 3 3 1
III 2.6 2.7 1
rv
3 3 1
V 4 4 3
VI 8 7 8 Lugng dong chay miia kiet tai Xuan Khanh tu dap dang Bai Thugng.
giam thdp nhat la do dong chay tren song Chu ^ong chay m lan nhdt song Chu thuong xudt da bi chuyen vao he thong thiiy nong song Chu ^^^^ ^^^ ^hang DC, t k sudt 41.5%
Bang 6. Tan suat xuat hien dong chay lii tai tram Cua Dgt Tram
Cua Dat V 2.4
VI 0
VII 4.9
VIII 19.5
IX 41.5
X 24.4
XI 7 Tren song Chu tai Xuan Khanh euong suat
muc nuoc lu binh quan khoang 15-20 cm/h, cao nhdt dgt 80-100 cm/h.
Kit qua khao sat do dae thuy van tren tuyin song Chu, tgi hai trgm TVSC2 thugng luu nga
ba song Chu-song Am va TVSC3 thugng luu nga ba song Chu-song Ma trong miia kiet (tu ngay 10-15/5/2014 - vi tri cac tram nhu Hinh 2) cho thdy luu toe dong chay tren tuyen song Chu khong Ion, trung binh dat 0,5m/s, luu toe
TAP CH( KHOA HQC VA C O N G N G H E T H O Y LOI S 6 26 - 2015 15
I KHOAHOC ^ . J . l . < l e l . < r e < ! l : ^
ddng chay 1cm nhit tai tram TVSC2 chi dat thuy tridu nen luu tde ddng chay ldn han c 0,65 m/s, tai tram TVSC3 do anh huong cua 1,45 m/s [3].
Bang 7. Cac dae trung thiiy van, thuy luc t?i tram TVSC2 va TVSC3 Tram do
TVSC2 TVSC3'''
Vmax ( m / s )
0.65 1.45
V T B ( m / s )
0.5 0.5
Q m a x ( m V s )
105 360
Qmin(m''/S)
76 -304 Ghi chii: Trgm TVSC3 la trgm dnh hudng cua thuy trieu
Tir nhiing thong ke tr6n cho thay, dong chay tren song Chu bien doi manh theo thoi gian va khSng gian: miia kiet keo dai tam thang va lugng dong chay chi chilm khoang 26% lugng dong chay nam lam bun cat long song va b6 song bi b6 roi, trong khi do lugng dong chay lu lan tSp trung trong thai gian ngan v6i euong suat lu len nhanh, luu toe dong chay lu Ion da lam sat 16 bo va gay dien biln b6i xoi long din nghiem trgng. Day ciing ehinh la mgt trong nhung nguyen nhan quan trgng nhdt anh hu6ng den qua trinh sgt 16 ba va biln dgng long dan song Chu.
- Yeu to bim cat:
Theo tai li?u nghien cuu truac day [2], ham lugng phu sa Ion nhdt vao miia lu dat 2,83 kg/m^ tai Xuan Khanh tren song Chu ngay 10/8/1976. Ham lugng bim cat trung binh tai Xuan Khanh la 192 g/m^ trung binh tgi song Am dgt 181g/m^ Song Chu chuyin vl hg du la 0,848 tri?u tdn phu sa. Tai Xuan Khanh he s6 xam th\rc dgt 114 tdn/km^.
Theo tai li^u khao sat do dgc mai tai hai trgm TVSC2 va TVSC3 tit 10-15/5/2014, ham lugng phil sa lan nhdt dgt 22,8g/m^ nh6 nhdt chi dgt 7,2g/m^ tai trgm TVSC2 va Ian nhdt dgt 149,3g/m^ nho nhdt dat 3,6 g/m^ tai tram TVSC3.
Nhu vSy, lugng biui cat song Chu chuyen ve ha du khong doi dao, thugc vao muc trung binh va dang co xu th§ giam ro rSt do cac ho ehiia thugng nguon da giir lai phdn lan lugng biin cat trong long ho. Sir thieu hut bim cat nay la nguydn nhan rSt quan trgng gay sat 16 bo va bien dgng long dan song Chu.
+ Anh hudng cuayeu td dia chdt:
Ket qua khoan khao sat dia chSt long song tii hg luu dap Bai Thugng dSn hgp luu song MS (Bang 8) g6m 13 h6 khoan tir HK-C4 din HK-C17 (Hinh 2) cho thdy vat lieu cac lop la bun set pha mau xam den; 16p 2 la cat hat to CO soi san mau xam vang, xam nau, bSo hoa nu6c chat vira; lop 3 la ddt cuoi soi lin cat mau xam vang, bao hoa nu6c eh^t vita-chat;
lop 4 la set pha mau xam nau trgng thai chay;
lap 5 la bim set pha lin trdm tich thuc vat mau xam den [3],
Theo cac kit qua phan tich cac lop dia chdt nhan thdy lop ddt 2, 3 co euong do chiu tai cao, it biln dgng, biln dgng tir trung bmh din Ion. Tuy nhien ciing la 16p dat roi do dinh kit nho de bi xoi m6n du6i tac dung eua d6ng nu6c. Trong khi do lop ddt 1, 4 va 5 co cuang do chiu tai thap va bi6n dang rdt manh, du6i tac dung cua dong chay de bi x6i mon bi xoi mon du6i tae dung ciia dong nu6c.
TAP CHf KHOA HQC VA CONG NGHE T H O Y lQ\ S 6 26 - 2015
KHUAHUC ^ . I . U M J M i l : ^
Bang 8. Bang tong hop cac chi tieu of ^ cua cac ldp biin cat long song Chu TT
1
2 3 4 5 6 7 8 9 10 11 12
13
Chi tieu d$c tnmg Thanh ph4n hat Cudi s6i> 2.0 mm Soi san: >2.0 mm Dam san: >2.0mm Cat : 0.05-2.0mm Bui : 0.005-0.05mm Set : <0.005mm Do am tu nhien Do am^oi h ^ chay Chi sd deo Dung trgng tu nhien Dmigjron^khd Khdi luong rieng Do lo rdng^
He sdron£t\r nhien Dg bao hoa L\rc dinh kit Gdc ma sdt trong Gdc nghieng ciia cat khi khd Gdc nghieng cua cat khi uat Cudng dg chiu tai qui udc
Ky hieu
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W
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Wn Tw Vc A n Eo G C
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Oc Uw
Ro Donvi
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%
% %
g/cm^
g/cm' g/cm^
%
%
kG/cm^
dd Dd kG/cm'
Lap 1
38.7 30.3 31.0 69.4 56.3 13.5 1.54 0.909 2.65 65.7 1.915J 96.0 0.015 2°21'
0.2 Lap 2
16.7 83.8 0.2 0.2 18.9
2.66
26"
21"
2 Lap 3
78.3 21.7
6.9
2.66
>3 Ldp 4
36.0 43.5 20.5 31.7 29.9 9.5 ^ 1.91 1.450 2.69 46.1 0.855 99.8 0.029 2°45'
0.3 Ldp 5
29.9 38.3 31.8 70.6 66.0 13.5 1.53 0.895 2.57 65.1 1.866 97.1 0.027 2°4*'
13 Nhu vgy, dia chat s6ng Chu dogn tir sau dap
Bai Thugng toi hgp luu vai song Ma thugc loai nin dia chdt ylu, do ket cau chii yeu tU cac logi vgt li?u b6 roi co d6 lien ket kem, do do long song de bj xoi 16 mgnh khi toe do
dong chay tang cao trong mua lu, vugt nguong khang xoi cho phep doi voi nhijng vat lieu bo roi. Theo ket qua nghien ciiu cua Vanoni (1975) da cong bo van toe dong chay co the kh6i dgng biin cat day nhu sau:
Bang 9. Van toe khoi d$ng cua cac loai hat bun cat theo Vanoni (1975) Loai hat bun cat
Cat rit thd Cat thd Cat trung binh Cat min Cat rit min Biin thd Bim trung binh Biin rat min
Kich cd* hat cat (mm) 2.0-1.0 1.0-0.5 0.5-0.25 0.25-0.125 0.125-0.062 0.062-0.031 0.031-0.016 0.016-0.008
Van toe khdi ddng (cm/s) 50 30 20 18 20 25 50 70
TAP CHl KHOA HOC VA CONG NGHE THCJY L f l l Sl5 26 - 2015
KHOA HQC
Til each xae dinh so bg tde do dong chay gidi han gay xdi bd, long dan nhu tren cd the thay tde dp gidi han ciia ddng nuoc khdng gay xdi Id ldng din sdng Chu khdng vugt qua ngudng cho phep (0.7 - 0.8ni/s). Trong thuc td, vao miia lu tde do ddng chay sdng Chu rat Ion, thudng vugt qua tde dp gidi han cho pliep nay gay ra xdi 16 manh va bidn dgng long dan. Ket qua la sat 16 bd xay ra 6 nhidu vi tri nhu da trinh bay d bang 1 va mdt sd hinh anh.
Ngoai ra, cac tuydn de ngan lii dgc sdng Chu dugc xay dap chu yeu tit cac loai vjt lieu tai cho, cd kdt cau bd rdi, dg lien kdt kem; thudng cd dg km bao hoa khi bi ngam nudc lau ngay nen rit dl hi ttugt 16, dd 16... cOng gdp phan lam giam dang kd muc dg an toan trong miia mua lu keo dai.
+ Anh hudng aia cdc hogt dong kinh te xg hgi:
Cimg vdi su phat tridn kmh td xa hdi tren luu v\rc, con ngudi ngay cang tac ddng nhieu han ddn ddng chay tu nhidn cua sdng phuc vu cac hoat ddng kinh td xa hdi. Mgt Uong nhimg tac dpng cua con ngudi cd anh hudng ldn nhat den doan sdng nghien cim la boat ddng xay dung cdng ninh thuy lgi (hd chiia, dap dang) va hoat dgng khai thac cat ldng sdng (dae biet la bom
hut true tiep cat dudi ldng sdng).
Tren ddng chinh sdng Chu thugng luu cd hai hd chira Ion dang hojt ddng la hd Ciia Djt (W = 1,364 ty- m'), hd Hiia Na (W = 533 tridu m'), Irung luu cd dap dang Bai Thugng (d|ip cao 23,5m). Cac cdng trinh nay cd mat tich cyc la cSt giam lii cho ha du trong miia lu, nang cao diu nudc ISy nuac tuoi cho ndng nghiep. Hien chua cd nghien ciiu cbi tidt danh gia anh hudng tieu cue cua cac cdng trinh nay ddn ddng chay sdng Chu, tuy nhien theo cac nghien ciiu til tnrdc den nay vd tac dgng cua hd chira da chi ra ^inh hudng tieu cue cua cdng trinh hd chira la se lam bien ddi chd dg thuy van thuy luc cua ddng chay tu nhien [7], [1], ngan ddng bim cat tit thugng ngudn, do dd se gay bidn ddi ldng dan ha du. Cd the ndi, bidn ddng long din doan sdng nghien cim cd tac dgng dang kd cua cac hd chiia thugng ngudn.
Trdn tuydn sdng Chu boat ddng khai thac cat trong nhOng nSm gin day da va dang bimg phat rit m^inh, gdm cd boat dpng khai thac cat dugc d p phep va khai thac cat trai phdp. Til 2008 ddn 2013 tinh Thanh Hda da d p phdp khoan tham dd va khai thac cat vdi tdng khdi lupng khai thac cat khoang 3,5 ttidu met khdi (Bang 10) tren tuyen sdng Chu.
Bang 10. Cac diem cap phep khoan tham dd va khai thac cat tren tuyen sdng Chu TT
1 2 3 4 5
So Quyet dinh Sd3715/QD-UBND Nam 2008 Sd 3716/QD-UBND Nam 2008 Sd3718/QD-UBND Nam 2008 Sd 3674/QD-UBND Nam 2011 Sd 3339/QD-UBND Nam 2012
Vi tri, dien tich, tru" lu'g'ng Ithai thac
Thi trin V ^ Ha (xa Thigu Hung) va xa Thidu Nguyen, huydn Thieu Hda; trir lugng: 885.159 m'
Xa Thieu Tan, huyen Thieu Hda;
Trir lugng: 933.168 m''
Xa Thieu Nguyen, huyen Thidu Hda;
Trir lugng: 817.068 m'
Xa Thidu Khanh, huyen Thieu Hda, tmh Thanh Hda;
DT; 4j5ha; trii lugng: 219.746 m'
Xa Xuan Hda, xa Xuan Tin va xa Thg Lap, huydn Thg Xuan, tinh Thanh Hda; DT: 7.0 ha; trii lugng: 127.203 m'
18 TAP CH( K H O A H O C V A C O N G N G H £ T H O Y LOI S 6 26 - 2015
KHOA HOC
TT 6 7 8
Sd Quylt dinh Sd 3340/QD-UBND Nam 2012 Sd 2909/QD-UBND Nam 2013 Sd 2910/QD-UBND Nam 2013
Vi tri, difu tich, trilr lugng khai thac
Xa Thg Thanh, huydn Thucmg Xuan, tinh Thanh Hda;
DT: 9,0 ha; tru: lupng: 51.395 m'
Tai md cat sd 1 la long sdng Chu d o ^ thugc xa Xuan Lai, huyen Thp Xuan, tinh Thanh Hda; tru' lugng; 177.000 m' Tai md cat sd 10 long sdng Chu d o ^ thugc xa Thg Trudng, huyen Thg Xuan, tmh Thanh Hda; trir lugng: 216.000 m' Ngudn tdi lieu: Sd Tdi ngiryen va Mdi trudng Thanh Hda, 2014
cae hogt dgng khai thae cat trai phep dien ra thuang xuyen, khoi lugng khai thae rat I6n va rat kho thong ke e\i the. Tuy nhien vai nhimg con so nhu tren da cho thay miic do anh huang cua hoat dOng khai thac cat den bien dgng long dan dogn song nghien eiiu la rat I6n.
IV. KET LUAN
(Jua viec phan tich bien dgr^ long dan song Chu dua vao tm H$u do dgc Hch sir gom tai li6u dia hinh, thuy van, dia chdt, anh vien tham va tai lieu khai thac eong trinh tren tuyen song, ngliien cuu da rut ra dugc m6t so ket lugn sau:
So bg xae djnh dugc cac ylu to chinh anh hu6ng dSn qua trinh bien dgng long dan la: cac yeu to thuy van (m\rc nuoc, luu lugng va bun cat) la yeu to tac dgng vao qua trinh thay doi t\r nhien cua long dan. Chi do dong chay da thay dii co ban va bdt lgi, trong khi do dia chat long song ha luu ylu de hi tac dgng ciia dong ehay, dgc bi6t la dong chay xilt vao mua lii gay xoi lien tuc. Hi$n tugng xoi sau xay ra chi trong vong mdy nam gdn day. Mat khac anh huang hogt dgng cua cac h6 chiia tr^n thugng ngu6n trong viec giir dong ehay, bao g6m ca lugng phu sa da lam mat can bang bim cat vimg ha du h6. Cac hoat dgng xay d\mg ho chira dieu tilt, dap ngan dong, hoat dgng khai thac cat da lam mdt can bdng biln cat nghiem trgng, din din chi dg thiiy dgng luc, bim cat, dia Wnh long dan bi tac dgng rit nhilu.
Nhu vgy, nhung phan tieh tr6n cho thdy long dlin song Chu biln doi theo thai gian vai xu
the xoi sau la chu yeu, day la mgt trong nhihig nguyen nhan gay ra sgt 16 ba song va gay nguy hiem, mat on dinh den cong trinh de dieu.
Trong tuang lai, neu eac tac dgng nay den ehe do dong ehay, biin cat khong dugc can tlu?p va dieu chinh kip thoi thi long dan song Chu khu vyc hg luu dap Cua Dat se con bien dgng mgnh, v6i nhieu diem sat 16 co cuang do mgnh hem xay ra tren dien rgng ban.
cac nhan dinh ve biSn dgng long dan song Chu ciing nhu ve nguyen nhan gay bien d6ng long din trong nghien eijru nay m6i can cU trSn phan tich s6 lieu do dgc Ueh sir thu thap dugc vl dia hinh, dia ehdt va thuy van va anh vien tham. Mat khac so li?u ve do dae ciing con ban chi, tren song Chu kh6ng co trgm thuy van quan trdc bim cat nao. Can co nhiing nghien cuu sau han vai chuoi so lieu day dii han va eac tinh toan dinh lugng de lam sang to nguyen nhan va quy luat bien dgng long din Cling nhu du bao xoi 16 phuc vu phat trien kinh te xa hgi.
LM cam on
Cac tac gia cua bai bao nay xin dugc cam on PGS.TS. Le Mgnh Himg da cho nhung y kiln dong gop quy bau trong qua trinh nghien cuu va chinh sua hoan thiSn bai bao. Nghien cuu nay nhan dugc kinh phi tir nguin ngan sach nha nuoc trong viec trien khai de tai nghien cuu thugc chuong trinh nghien cihi khoa hgc edp nha nu6c KC08/11-15.
TAP CHf KHOA HOC VA C O N G N G H $ T H O Y L O I S(5 26 - 2015
I KHOAHOC ^ E S 3 ! B ! 1 M
TAI LIEU THAM KHAO
[1]. Nguyen Tuin Anh va nnk, Nghien cuu du bdo xoi Id hg du song lo-Gdm khi cdng trinh thuy dien tuyen quang dua vdo van hdnh phdt dien vd chong lit, B& tai ddc lap d p nha nuac. Ha Ngi 2007;
[2]. Hd Viet Cuong, Le Manh Hiing va nnk, Khdo sdt, nghien ciru vd ldp dtf dn ddu tu xdy dung cdng trinh xit ly sgt la bd bien Sdm San, thj xd Sdm San, tinh Thanh Hoa, Ha Ndi 2011;
[3]. Nguyen Thanh Himg va nnk, Nghien ctcu ddnh gid tac dgng ciia cdc ho chUa thugng ngudn den bien dgng long ddn hg du, cifa sdng ven bien he thong song Md vd de xudt gidi phdp hgn ehe Idc dgng bdt lgi nhdm phdt trien ben vimg, De tai cap nha nudc KC08- 32/11-15, Phdng Thi nghidm ttgng diem Qudc gia ve dgng luc hgc sdng bidn. Ha Ndi 2014-2015;
[4]. Kixelep P.G (chu bidn), Sd tgy tinh todn thuy luc. NXB "Mir". Matxeva, 1984 (Luu Cdng Dao, Nguyen Tai dich tir tieng Nga);
[5]. Nguydn Quang Trung va nnk, Nghien citu di xudt gidi phdp gidm thiiu dnh huang cia dong chdy kiet phuc va sdn xuat nong nghiep, thdy sdn viing ha du song Cd vd sdng MS, Ha Ngi 2013.
[6]. Sd Ndng nghiep & PTNT Thanh Hda, Bdo edo ddnh gid chdt lugmg de diiu truac W nam 2014 - tinh Thanh Hda, Thanh Hda 2014.
[7]. Vti Tat Uyen, Nghien ciru du bdo biin ddi long ddn sdng Dd, song Hdng khi thiiy dien Hoa Binh vgn hdnh, Vien Khoa hgc Thuy Lgi, Dd tai KHCN 06.05 (1978-1985).
[8]. Vidn Quy hoach Thuy lgi, Quy hogch phdng chdng la he thdng sdng Mg, Ha Ndi 2010.
[9]. Vanoni, V.A, (1975). Sedimentation Engineering. ASCE Task Commitee for the preparation of the Mannual on Sedimentation of the Sedimentation Commitee of the Hydraulic Division (reprinted 1977).
TAP CHl KHOA HOC VA CONG NGHE T H C Y LOI S(5 26 - 2015
