Nghien cdu - Trao do'i
Quan he thuy iuc giiifa nirac duoii flat trong cac tram tich De tii voi nudic song Hong
Of Dong b^ng Dac Do
Quan hg thUy lUc Id sy tuong tdc cung ed'p qua lai giya cdc nguon nude tren mdt vd nudc dudi dd't hodc giya cac ngudn nude dudi dd't vdi nhau trong cdc dilu kien tu nhien cung nhu cd su tac dpng eua eon ngudi. Viec nghidn cUu, xde dinh quan he thuy IUC cd y nghTa to ldn ve mdt khoa hoc cung nhu giai ede bdl todn thyc te. Xdc dinh ro quan he thuy luc gdp phan xac dinh rd ngudn hinh thdnh try lupng phue vu cho vide danh gid try lupng khai thac nudc dudi da't vd ddc biet, xde dinh rd quan he thuy lUe ed ^ nghla rat to ldn ddi vdi ludn chUng l i ^ chpn ede giai phdp xdy dyng cdc cdng trinh khai thdc thd'm ven bd.
Cdc kieu quan he thuy lyc giua nirdc dirdi dat va nudc song Cdc kit qua nghien quan he thiiy lyc giua nudc dudi ddt va nudc sdng da xac djnh dupe 4 kieu quan he thuy lyc sau ddy.
Kiiu 1: Phd biln trong ddi dU am, chO ylu dpc theo cdc sdng Idn. Trong dieu kien ty nhien, phdn Idn thdi gian trong ndm, sdng hd dugc nude dudi ddt eung d p , ddng Chay ngam hudng ra phfa sdng, hd. Chl trong mua lu hodc eac thdi ky lu, nudc dudi dit mdi tam thdi dupc mrdc sdng cung c^p. SU cung cdp ndy chl xay ra d ddi ven bd Idm cho ddng chdy dudi dat cd phUdng ngUpc lai, tyc Id ty phia sdng, ho.
O PGS.TS. NGUYEN VAN OAN Vi$n Tdi nguydn mdi truang nudc
ThS. NGUYEN MINH LAN
Li6n dodn Quy ho?ch vd Didu tra tdi nguydn nudc midn Bdc Chidu rOng eCia ddi t^ Id thudn vdi
d$ ldn cCia sdng, bidn d^ dao ddng myc nudc sdng, hd, tfnh thim ciia ddt dd ehya nudc... Khi ed cdng trinh khai thde ven bd vdi mye nudc ha thd'p xudng dudi myc nudc sdng thi nude sdng ludn ludn eung cdp cho nude dUdi dd't.
Kiiu 2: Phd biln d cdc vCing thilu Im hodc cdc vCing ed cd'u true ddc biet thudn Ipi d l nude mdt quanh ndm cung d p cho nudc dudi ddt. Vdo thdi ki lu, gid tn eung d p tdng len. Khi cd cdng trinh khai thde ven bd sy eung d p edng tdng.
Kliu 3: Ddc trung cho trudng hpp sy dao ddng eua muc nudc sdng khdng Idn. Do d$ nghidng thu:^ lyc ciia nudc dudi ddt d ddi ven sdng Idn ndn khdng cd sycung d p eua sdng. Trong thdi ky IQ, qud trinh thodt cCia nudc dudi ddt khdng nhyng khdng dyng lai md cdn tdng ldn do sy gia tdng lupng cung d p . Cdc cdng trlnh khai thde ven bd da sd trUdng hpp khdng ha thd'p dupc muc nude dudi ddt sdu hon nudc mdt nen khong nhdn dupe su cung d p ty sdng, neu ha thdp xudng dudi muc nudc mdt thi lupng cung d p cQng khdng ddng k l .
Kiiu 4: Ld kilu quan he thuy lue grOa nudc mdt vd nude cd dp nSm sdu dupc ngdn d c h bdl d c Idp thdm nudc ylu. Trong da sd trudng hpp, mUc dp luc ciia ting
ehya nude eao hdn muc nudc mat ndn nudc dudi ddt eung d p cho nudc mdt bdng thim xuydn qua ldp thdm nudc ylu. Nlu mye dp luc ha thd'p hdn mUC nudc mdt thi xdy ra hidn tupng ngupe lai. Khi cd c&ig trinh khai thdc ven bd, muc nudc dudi ddt ha thifp. nudc sdng se eung d p eho cdng trinh khai thac nhd thdm xuyen qua Idp thim ylu ndn lupng b l sung khdng Idn.
Nhu vdy, viec xdy dung cdng trinh khai thac nUde tha'm ven bii cd hidu qud nhd't khi d e nguon nudc mdt CO quan he thuy lire vdi nudc dudi dd't kieu 1 va kilu 2 mo ta trdn ddy. Odi vdi kilu quan he 3 phai dip ddp d l ndng cao mifC nudc mdt, dd'i vdi kieu quan he 4 thi phai khoan them cdc lo khoan dp nudc ty trdn xudng.
D$c diem quan he thuy lyc giQa nudc dudi dat d c tram tich Oe ty vdi nudc sdng
Sdng Hdng Id con sdng I6n nhdt d mien Bae nude ta. Tnidc khi chdy vdo Odng bing Bic Bd 6 Viet Tri duoc hpp luu vdi sdng L6 va sdng Da. sdng Hdng chdy qua cac tinh VTnh Phuc, Hung Ydn, Ha Nam, Nam Dinh, Thai Binh vd TP.
Hd Ndi. Ddng thdi nude dudi d^t vOng ven sdng Hdng ed ddc ^em Id ddng thdi thuy vdn, trong d6 t6n tai 3 kilu quan hd giya nUdc sfing vd nude dudi da't, dd la cdc kilu 1, 2 vd 4 md td tren ddy.
2 6 Tai nguyen vd fvlfli traong | KM-Thang 3/2013
KiSu 1: Phd biln hdn ca, phdn bd b bd Bic sdng Hdng doan tU Viet Tri de'n Xudn Canh - Ddng Anh cOa TP. Ha Ndi va d bd nam doan ty Ba Vi din khoang hd't dja phdn khu vue ndi thdnh TP. Hd Ndi. 6 day, hau hit thdi gian trong ndm, nUdc dudi dat cung d p eho nudc sdng Hdng ndn ddng chay dudi ddt ed hudng tU Ble xudng Nam (d bd Bac) vd ty Nam Idn Bdc (d bd Nam). Chi cd thdi kJ lu (thdng 7, 8) muc nudc sdng ddng cao, nudc sdng Hdng mdi tam cung d p cho nUdc dudi ddt, khi dd ddng chdy cd hudng ngupc lai.
Tuy nhidn, sy cung d p k l trdn chi xay ra 6 ddi gan sdng. Myc nUde sdng dng cao thl ddi dnh hudng dng rdng tUc Id lan tmyln dupe cdng xa. Dilu ndy, dugc mmh hpa bdng dd thj muc nude dudi ddt ve theo tuyen d vung Vfnh Thjnh - Vfnh Tudng tinh VTnh Phue (xem hinh 1). Trong dd, cdc lo khoan quan trac dong thdi nUdc dudi dd't tang qp dupc bd tri thanh tuyen tU sdng Hong ve phfa Bac ( d t vudng gdc vdi sdng Hdng) gdm: Q10 d sat met nUdc, Q9a deh mep nudc khoang 2,5 km, Q8a each mep nude khoang 3,5 km, Q7 d c h mep nude khoang 7 km.
Phan tfch dd thj hinh 1 cho Uiay, vdo miJa khd can (thang 2, 6 va 10 tren hinh ve), muc nudc dudi dat cao hdn mye nudc sdng Hdng, eang xa sdng thi cdng cao hdn Idm cho ddng chdy dudi dat chay ve phfa sdng, tyc la cd phUdng Bdc - Nam. Chi d vdo d c thdi ki lu (thdng 7) muc nude sdng Hdng dang eao, cung d p cho nudc dudi dat lam cho ddng chay dudi dit cd phuong ngupc lai.
Kiiu 2: Phd biln han chl, chi quan sat dUde 6 khoanh Q. Long Bien - H. Gia Ldm ciia TP Hd Npi, d dd nirdc sdng ludn ludn cung d p cho nudc dudi ddt. Dilu ndy dupc minh hpa bdng tdi lieu quan trie d cac Id khoan mang ludi khu vyc vd mang Ha Ndi dugc bd tri d sdt mep
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Hinh 2. Do thi muc nudc dudi dit tdng qp d cac cdng trinh quan trac trdn tuyen vung Long Bidn - Gia Lam
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Hinh 3. D6 thi dao ddng muc nudc sdng Hong vd nudc dudi dat tdng Qp vdng Duy Tidn - Hd Nam
nude sdng Dudng va xep thdnh tuyen theo phuong Tdy Ble - Ddng Nam gdm: Q121 d sdt mep nude sdng Dudng, P13a each mep nudc sdng Dudng khodng 2,0 km, P15a
cdch mep nUdc sdng Dudng khoang 4 km, Q120a deh mep nudc sdng Dudng khoang 10 km, 0119a cdch mep nudc sdng Dudng gan 20 km. Dd thi myc T6I nguyen va M6I tnidng | W1 • Thinn 3/2013 2 7
nudc d cdc cdng trinh quan trie tren tuyen ve eho cdc thdi dilm khac nhau the hien tren hlnh 2.
Phan tfch dd thj hinh 2 eho thd'y, nudc dUdi dd't lidn tyc dupe nudc sdng Hdng vd sdng Dudng eung d p ndn ed phUdng Tdy Ble - Dong Nam d td't cd thdi gian Irong ndm (myc nudc lo khoan P15a trdn hinh ve ha thd'p Id do khai thdc nudc dudi dd't vung Sdi Odng).
Kiiu 3: Phd bid'n ci vung ven sdng Hdng doan tU khodng hit dia phdn ndi thdnh TP Hd Ndi trd xudng. Thudc kilu ndy c6 2 phy kieu.
Phu kiiu thif nhit phdn bd d phia td ngan sdng Hdng thudc dja phdn tinh Hung Yen. 6 dd, nudc sdng Hdng ludn ludn eung edp cho nudc dudi dd't tUdng ty kieu 2 md ta d vung Long Bien - Gia Ldm, song phai nhd thdm xuyen qua cdc thdnh tao thim nude yeu Idm eho phuong ddng chay dudi dat ed phuong Tdy Tay Bic din Ddng Ddng Nam.
Phi^ kiiu tha 2 phdn bd d hyu ngan sdng Hdng thudc dja phdn TP.
Hd NOi vd tinh Hd Nam. 6 dd, da sd thdi gian trong ndm, nUde dudi dd't eung d p cho sdng Hdng Idm cho ddng chdy dudi dit cd phUOng gin Tdy - Ddng. Vdo thdi ki 10 nudc sdng Hdng do ddng cao cung d p eho nudc dudi dit Idm cho ddng chdy dudi dd'i cd phUdng ngupc lai.
Tdi lidu mlnh hpa Id dd thj myc nude sdng Hdng lal tram do Hung Ydn vd cdc Id khoan quan trie tang qp dupc bd trf thdnh tuyin vudng gdc vdi sdng Hdng vung Duy Tien Hd Nam d hinh 3, Irong dd l6 khoan Q88b each mep nude sdng khodng 1 km, l5 khoan Q87b deh mdp nudc sdng khodng 2 km. Quan sdt trdn dd thj cho thdy v l mua khd, myc nude dudi dit ting qp d d 2 l6 khoan deu cao hpn mUC nudc sdng Hdng, tyc Id nUdc dudi dil phdi thoat ra sdng, phudng ddng chdy dudi dd't sd tU Tdy sang Odng, cdn ve mua lu muc nude sdng Hdng eao hdn rdt nhieu muc nude dudi ddt se
Hinh 4. Sd d6 phdn vung quan hd thOy luc gida nudc du&i dit vd sdng Hdng
cung d p cho nudc dudi dit, ddng chdy dudi dd't se cd phUdng ngupc lai. Bidn d$ dao ddng ndm cOa miri:
nUdc dudi ddt rit nhd chdng minh v l mdi quan he thi^y lyc rdt ylu, sir eung d p qua lai khdng taic tilp md phdi thdng qua thim xuygn qua cdc thdnh tao thim nudc ylu.
Phan vung quan he thuy \ac Oia ph$n phfa Bic sdng Hong doan ty Vr0t Tri din chd tdch ra sdng Dudng vd dia phdn phfa nam sdng Hdng tU Ba Vi din khodng h6 khu vyc n^i thdnh eua TP Hd N6i thude kllu quan h^ thi^iy lyc 1.
Trong dd, dja phdn ndi thdnh vd huydn Ty Lidm thudc TP. Hd N6i dang c6 d n g trinh khai thdc ven sdng ndn thudc kilu lb, dien tfch d n lai cua vung ndy thupc kilu 1a.
Dja phdn viing Long Bidn-Gia Ldm cda TP. Hd Ndi thudc kieu quan he thOy luc 2 (2a}.
Dja phdn tU khodng hit noi thdnh TP. Hd Ndi trd xudng thuoc kieu quan hd thuy lUC 4. Trong do phia ta ngan sdng Hdng thupc phu kieu 4-2, tyc Id sdng Hdng luon ludn cung d p cho nudc dudi dat nhung khdng tryc tilp md thdng qua d c thdnh tao thim nude kem.
Phan huu ngan sdng Hdng thuoc phu kilu 4-2. tyc Id ve mua kho nude dudi ddt cung d p cho song Hdng, cdn v l mua lu nudc song Hdng eung d p cho nude du^ all, song khdng true tilp md phai thdng qua d c thdnh tao thim nudc y l u .
Vi^c phdn dupc d c vising co d c kieu quan hd thCiy luc khac nhau giOa nude dudi dat vd nudc sdng Hdng nhu tren cd J nghla rat to Idn ve mdt khoa hoc cung nhi/
thyc tiln trong viec xac dinh nguon hinh thdnh trii' lupng khai thdc ni/dc dudi dd't trong dilu kidn tu nhien cung nhu khai nude dudi dit va ddc bidt, cd y nghTa to Idn de ludn chiJitig lu^ chpn cdc giai phdp xdy dung d e cdng trinh khai thdc thim ven bd.B
2 8 Tai nguygn vd ivlQl truong I KM • m n g 3/2013
