Thuc tieh - Kinh nghiem
^Giai phap cap nudfc cho vung cufa song Ban Thach
O TS. TONG NGOC THANH, ThS. N G U Y I N CHI NGHIA Tivng tam Quy hoach vi Dieu tra tai nguyen nude Quoc gia
T
rong nhiing nam gan day, tfnh Phii Yin eo nhieu chfnh sach thu htit dau tuva hien dang eo nhieu cae dUan Idn trien khai xay dt/ng tren dja ban tfnh. Van decap nifde cho cae duan nay dang rai cap thiii vi can phai dau tunghien cthi sdm. Becd casd xac dinh ngudn cap nudc Idn cho cac nhu cau nude khu vUt nay, td ket qua tdng hap cae nghien etiu, dieu tra eaban TNN, dae trung ngudn nude va hien trang sd dung nudc luu viJt song (LVS) Ban Thach, cac nhom tac gia cung dexuai cae giai phap khai thae cap nudc cho eae mue dfch phat trien KT-XH tren dja ban vung cus song Ban Thach, tfnh Phti Yen.Dac diem dja hinh, dja mao Sdng Ban Thach edn daac gpi la sdng Banh Lai d thUdng luu va sdng Da Ndng d phia gan bien, LVS Bin Thach bao trum hau hit dja phan hai huyen Tay Hoa va Ddng Hoa vdi dien tfeh LVS la 592 km2. Trong nhCmg nam gan day, cung vdi chinh sich uu lien phat triln kinh te miln Trung cung nhu chfnh sach thu hut dau tucda tlnh Phd Yen nen cd nhieu dp an mdi dupc nudc ngoai dau tu xay dyng.
Cac dp an dupc dau tU deu can den nude, do dd, van de ci'p nudc cho cac du an dupc dat ra va tinh eung nhu cac don vj dau tU quan tam nghien eCru,
LUU vuc sdng Ban Thach cd long dien tfch tp nhien gan 600 km- nam tach biet vdi eae khu vpe khac eda tinh Phu Yen bdi sdng Oa Rang d phia Bae va cac day nui cao d phfa Nam, Dia hinh lull vpe cd dp eao thay ddi manh
vdi dp cao giam dan IQ phfa Tay ra phfa Odng. Die diem Idp phd LVS bao gdm ea hai dang la die trung ddng bang va ddi ndi. Phfa Odng luu vUc giap Bien Ddng, phfa Tay la nui vd vung trung tam la vung trung. Tham thpc vat trong luu vpe vdi vung trung t i m ehu ye'u l i trdng Ida nude, vung ddi nui phfa Nam ehd ye'u l i rUng thua tai sinh va cay bui ven bien.
Vung dien tfch phfa Ddng, phan giap bien phit trien nudi trdng thuy hai san.
Ddng ehay LVS Ban Thach chia lam hai mua rd ret. Mua can keo dai IQ thing 1 de'n he't thing 8. V i o thing 5, 6 ddng chay cd ting cudng nhd mUa lieu man, nhOng vin mang tfnh chat ddng chay mua can. Thing 7, 8 ddng chay tren sdng khu vac giam cham va xui't hien mpt cue tiiu phy trong nim, cd nim ddng chay nhd nhi't xui't hien vao thdi ky
nay. Vao mua khd, sdng Mdi vd sdng Nude Trong thude sdng nhanh cda sdng Ban Thach khdng bo sung hoae b l sung rat ft nude cho sdng Ban Thach vi hiin tai tren cac sdng nhanh niy cd dap ngin nude d l tfeh nude phue vy cho ludi va sinh hoat tren hai sdng nay. Do viy, lupng nudc eung cap ehinh eho ha du sdng Ban Thach va eda thupng ngudn eda sdng va cd ten gpi l i sdng Banh Lai. Luu lupng trung binh nudc sdng Ban Thach khoang 31,4 m%, tdng lapng ddng ehay nam 990 trieu m-*, mddun ddng chay trung binh 53 l/s km^. dp sau ddng chay trung binh 1670 mm.
Tren cd sd tai lieu do dac thing 5 nam 2014, da tinh dupe lull lupng ddng mdi tradng so bp l i 133.066 mVngay.
Qua cac k i t qua dieu tra khao sal tai nguyen NDO cda Lien doan QH&DT TNN miln 3 4 Tdi nguyen yg Mdi trudng | Ky 1 - Thang g/201ft
Tnjng eho thay, NDD trong LVS Bin Thach tdn lai chu yeu trong eae tram tfch de iQ ludi holocen phin bd d tren m i l v i pleistocen phan bd d dudi siu. Op sau phan bd trung binh cda ndc tang pleis- tocen d phfa huyen Ddng Hoa la . 50- 60 m. Hai tang chQa nudc ' niy bj phin cat manh bdi he
thdng sdng sudi v i dirt giy.
Ngudn cap nudc chfnh cho lang chQa nUde din td nude mua.
Nhin djnh rang nUdc trong tang holocen dupc bd cap IP mua, tudi do tham qua Idp tram tfeh be mat phfa tren xudng. Nude trong lang Pleistocen dddc bd cap chd yeu IQ nude ngam vao cae ddi dap vd eda ddt gay trong eae da granit phin bd phfa Nam. Nudc trong tang holocen d phfa dudi cau Bin Thach cd do tdng khoang hoi dao ddng tU 4-6g/l. Nudc trong tram tfeh Pleistocen nhin , Chung la nude nhat.
Giai phip quy hoach cap nudc Theo quy hoach ci'p nude eda tlnh Phd Yin tai Quyet djnh sd 251/QO-UBND phe duyet quy hoaeh tdng t h i sQ dyng TNN tlnh Phd Yen de'n nim 2015 v i d u bao din nim 2020 dupc chia thinh 4 vung quy hoaeh tdng the sQ dyng TNN: Vung thuan Ipi, vung tuong ddi thuan Ipi, vung khd khin v i vung rd't khd khin. Trong dd. vung cda sdng Bin Thach dupe xep vio vung vdng 11. vdng tuong ddi thuin lpi eho quy hoach khai thic, sQ dyng eae ngudn nude. Vung niy gdm 31 x i . thj trin thude dja hinh ddng blng. cdn cit ven biln ed ngudn nude mit, nude mua phong phd v i nudc ngam d mQc chQa nude trung binh. Nudc ngam d vung niy van trong cic tang ChQa nudc Holocen, Pleistocen gdm trim tfch sdng, biln-gid, vdi b l diy tang ehCra nude nhd, dien
phin bd ban che hon, cac Id khoan cap nudc ed the khoan siu 50 - 70 m, luu lupng khai thic khoang 100 - 250 m-'/ng, cung cap cho cae nhu eau d quy md vQa va nhd, neu vdi quy md cap nudc Idn cho cdng nghiep hoic tadi thi cd t h i sQ dyng nude mat bang he thdng dap dang, hd chda nhung phai chu y xQ ly chi't lupng nadc, nha't la eho san xua't cdng nghiep. De cap nude eho cac cym dan eu vdi quy md nhd trong vimg nay vdn sQ dyng eae Id khoan ndng dudng kfnh nhd, hoac gieng dao dudng kfnh ldn tren eae khu cdn cat ven biln hoic ddng bdng tinh Phu Yen.
Theo t i i lieu nghien ciru cho thi'y, nudc mat LVS Ban Thach vio mda khd khdng dd cung ci'p eho nhu eau hien tai (neu tfnh ea phan nude ci'p theo quy hoaeh sQdyng nudc IQnim 2015). Cdn NDD trong tram ti'ch pleistocen vung thim dd tfnh tQ dudng qude Id 1 ra blln ehi dd eung cap tdi da la 30.000 mVng. Vay, gia thie't phai cap nude Idn vao mua khd thi lupng nude ldi da dip Qng la 50.000 m^/ng.dem (25,000-30.000 m^/ng.dem tQ nudc ngam v i con sd tuong tp vdi nudc mit).
De ci'p nudc Idn trong khu vpe nay can phai ket hpp cic ngudn nude khac nhau, trong dd nudc m i l v i nude ngam ddng vai trd chd dao. Cic tieu chf d l lua chpn phuong an ci'p nUdc cda tinh bao gdm:
Thd nhat giam tdi da cac tie ddng den eac edng trinh hien cd trong khu vpe, cie anh hudng den mdi trudng va dieu kien KT-XH eda huyen Odng Hoa ndi rieng va cda LVS Bin Thach ndi chung.
Cic phuong an thim dd dua ra phai cd khdi lupng cdng tic thim
dd hc^ ly va kinh te phu hpp de xic djnh, Ipa chon phue vy xay dung dupc cic cdng trinh cap nude bao dam khai thae va sQ dyng lau dii.
Thd hai, uu lien cac cdng trinh thudc quy hoach nam trong huyen Odng Hoa, gan khu vpe cQa sdng de chd dpng trong khai thic v i giam chi phi van ehuyen nude, tang mQc dp an toan cap nude.
Thd ba, phd hpp vdi eac quy djnh cda phip luat Viet Nam ve quan ly TNN.
ThU tu, tren co sd kit qua thu thip t i l lieu, dilu tra khao sat va chinh ly sd lieu dieu tra TNN cho Ihay, ngudn nudc cung nghien cQu rat ban che. TrQ lupng khai thic nudc mit d thdi dilm mua khd cd the khai thic td'i da tQ 40.000-50.000 m^/ng.dem va NDD la 30.000 mVng, Theo nhdm nghien cQu. phuong an hieu qua de thpc hien ede bude liep theo hudng tdi mue lieu khai thde cap nude ldn eho vung nghien cQu Id kel hpp khai thae NDD va nude tham lpc phia tren dip ngdn mdn dupc xiy dung theo Quy hoaeh cda tinh Phu Yen den nim 2015 va dp bao den ndm 2020. LUpng nude tdi da ed the khai thae ket hpp ea NDD va nude thi'm Ipc dao dpng trong khoang tQ 60.000 m^/ng dem den 100.000 m7ng dem tuy thudc vao mua. Di phuong i n cap nude Idn cd the thuc hien dupe ddi hdi phai cd sp vio cudc eda UBND tlnh Phu Yen, eae sd, ban, nginh, ehinh quyen dja phuong huyen Ddng Hoa cung cae chd dau tu vd don vj tu cd ning lpc dieu tra xac djnh npi dung can lam vd tien hanh dilu tra. thim dd ti my ngudn nudc phye vu yeu eau ci'p nude ldn."
Tgi nguyen vd Moi trudng | Ky 1 - Thing 9/201ft 3 5