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36(2), 160 168 Tap chi CAC KHOA HOC V£ TRAI B A T "^NGHIEN CUtr DANH GIA HAN KHI TUONG TINH QUANG TRI DOAN DOAN TUAN, NGUYEN VAN HOANG, NGUYEN VAN LOl Email Doandoantuan@gmaiI com ''''Trung tdm PIM Vien[.]
36(2), 160-168 Tap chi CAC KHOA HOC V£ TRAI B A T "^NGHIEN CUtr DANH GIA HAN KHI TUONG TINH Q U A N G TRI DOAN DOAN TUAN, NGUYEN VAN HOANG, NGUYEN VAN LOl Email: Doandoantuan@gmaiI.com 'Trung tdm PIM-Vien Khoa hoc Thuy lai Viit Nam ^Vien Dia chdt, Viin Hdn Idm Khoa hoc vd Cong nghe Viet Nam ^Trung tdm Tu vdn Chuyin giao Cong nghe Thuy l(fi Bo NN&PTNT Ngaynhanbai: 10-9-2013 Md dau Qudng Tri vdi dieu kien dia hinh ddc, cac sdng ngdn, khdng cd kha ndng trd nudc; ddi cdn cat ven bidn cao, vd dugc coi la vung cd hdu kha khde nghidt, nhiet ldn nhdt ed len den tren 40°C kem theo gid Tay Nam khd ndng tir thang din thdng thudng gdy ndn han hdn, Cdc dgt han hdn trAm trgng thudng xuyen dien nhu dgt ban nam 1992-1993, muc nudc cdc hd chiia ldn ddu d dudi myc nudc chet, man xam nhap sau vao cac cua sdng tdi 10km, dgt han ban thidu nudc nam 1997-1998, thang ddu nam 1998 lugng mua binh qudn chi dat 30-70% ciing ky, tdng sd 85 hd vira va todn bd hd nhd deu khd can [5] Cd loai han ban dugc phdn chia: (i) Han tugng; (ii) Han ndng nghiep; (iii) Han thiiy van va (iv) H^in kinh td - xd hgi, Trong dd ban tugng phan anh mdt each khdch quan nhdt nguyen nhdn ve dieu kidn hau thdi tidt vd Id loai ban ma khdng cd kha ndng ngdn ngua dugc Trong khudn khd bdi viet se trinh bay ket qud nghidn ciiu vd thyc trang ban tugng khu vyc tinh Quang Tri va sir dung sd lieu quan trdc tugng tai tram Ddng Hd [6] nham xac dinh quy ludt ban hdn ddi vdi tinh Quang Tri gdp phan cho cdng tac chudn bi irng phd vdi ban hdn, phat trien KT-XH cd tinh ddn nil ro h^n hdn, phat trien ngudn nudc cd tinh ddn dac trung ban khu vuc Sdc diem khf hlu-khi tirong tinh Quang Tri Quang Tri cd chd dd hau nhiet ddi gid miia vdi nhiing net dj thudng phan anh anh hudng manh 160 cua dia hinh Trudng San ddi vdi hoan luu quydn: Di thudng: cd mua mua lu xuat hi^n Thu Ddng, chdnh Idch nhidt dd giQa thdng ndng nhit vd lanh nhdt kha cao, tdi 9-10°C [3] Tai ddy cd nhidu hien tugng thdi tiet dac biet, mang tinh chdt thien tai nhu bao, mua ldn gay lu lut, gid Tdy khd ndng,, vd dugc xem Id viing cd hdu khd khac nghidt Chd dd biVc xa, nang v^ mSy: biic xa tdng cdng ciia Qudng Tri dao ddng khoang 100-130 Kcal/cm^/nam Sd gid ndng khd cao, trung binh 56 gid/ngay, cd sy phan hda theo thai gian vd khdng gian rd ret: mien Ddng cd tdng sd gid ndng len tdi" 1.910 gid, mien Tdy chi dat 1.840 gid Cac thdng cd sd gid nang cao Id thdng 5, 6, 7, 8, dat trdn 200 gid, Phdn ldn thdi gian nam cd lugng mdy khoang 70 - 80% bdu trdi trd len, lugng may mua ddng thudng nhieu hon miia ha, Trong nhiing thdng mua ddng lugng may trung binh thdng d^t 80% bau trdi, Trong miia ddng mdi thang cd 15 20 nhidu mdy d vung ddng bang ven bidn,17 22 d vimg ddi niii Miia he trung binh mSi thdng cd 10- 15 nhidu mdy [4] Che dd gid; hang nam cd hai mua gid chinh Id gid miia ddng vd gid miia Ci viing ddng bdng ven bidn vd hdi ddo, ve miia ddng hudng gid thjnh hanh chu ydu Id Tdy - Bdc Xen kd giua hai dgt gid miia Ddng Bdc Id nhihig gid Ddng hode Ddng - Nam Vd miia ha, hudng gid thinh hanh Id hudng tdy - nam Ngodi ra, cdn cd hudng gid khde thdi xen ke theo hudng ddng hode ddng - nam Tdc dg gid trung binh ndm 2,4 - 2,6 m/s Ch4 di^ nhiet: chd dp nhidt ndm bien ddi khd phiic t^p, chia 1dm bai miia rd ret, mua he cd nen nhiet kha cao, mua ddng ndn nhiet thdp, bidn dO dao dgng nhidt ngdy Idn Dac biet nhiet dg cd su phan hda rdt ldn theo cao dja hinh, cdng ldn cao tdng nhiet vd nhiet dd trung binh ndm cang thdp Nhidt dg trung binh cdc thdng miia ddng xu6ng dudi 19°C chi phdn bd d khu vyc vung niii phia Tay nhu d Khe Sanh Nhidt trung binh nam cd xu hudng tang ddn tit Bac vao Nam vd gidm ddn tu ddng sang tay Nhidt cao nhdt cd the ldn ddn 42,1°C (Ddng Ha), nhiet khdng thap nhat vao khoang 7,7''C (Khe Sanh) Bidn nhidt ngdy dem trung binh nam tai tinh Quang Tri dao ddng kha ldn, khoang tii 4,5°C d Cdn Cd vd den 7,2°C d Khe Sanh Od am khdng khi: Quang Tri cd dp am tucmg ddi cao dat gia tri trung bmh 83-88% Thdng cd dm thdp nhdt dat trdn 70%, dg dm tdi thdp tuydt ddi cd thd xudng ddn 19-28% theo timg noi Sy chenh lech gi&a vung thdp va viing cao cung khdng qud 10% Chi cd thang tai Khe Sanh (thdng 11 va 12) dm ldn tdi tren 90% Mdt dac didm ddng luu y ve tinh chat cyc doan cua dp am the hidn d chd nhiing giai doan am udt keo ddi cung cd thd xudt hidn nhiing ngdy khd ndng dg dm tdi thap tuy^t ddi cd thd xudng den mirc thap ky luc nhu d Tuydn Hod vd Khe Sanh thai ky am udt cua thdng 2, Mua: Quang Tri cd lugng mua binh quan khd cao, d viing nui, trung du vd ddng bdng ven bidn Id 2.200 - 2.600 mm Tai cac thung lung, niii thdp va vung cat ven bien vd hdi dao, tdng iuong mua dat dudi 2.200 mm Miia mua nhidu bdt ddu tir thdng den thdng 12 d cac viing niii, trung du, vimg ddng bdng ven biln va bdi dao Lugng mua tap trung chii ydu vdo cdc thang 9, 10 vd 11, chiem tdi 55 56% lugng mua nam, 70 - 80% lugng mua miia Miia khd Id thai ky boat ddng ciia gid miia Tay Nam la cdc thang lien tuc cd lugng mua dudi 100 mm Tdng lugng mua tir thang din thdng chi d^t - 8% lugng mua nam Trung binh hang nam Qudng Tri cd khodng 143 - 161 ngdy mua [1], Lugng mua ngdy cyc dgi thudng khodng 400 mm/ngdy, tham cbi cd noi nhu d Cdn Cd vdo ngdy 22/9/1979 quan trdc dugc lugng mua ngdy tdi 727,5mm/ngay, gdn bdng 1/3 tdng lugng mua ndm Phdn phdi mua ndm theo thang tai cdc tram mua tinh Qudng Tri cho thdy phdn hda dang khde bidt: dang dinh (mdt ndm cd cue d^i vd cue tieu) vd dang dinh (mdt nam cd cue dai vd cue tidu) Dang dinh d | c trung cho cac khu vuc thudc sudn Ddng Trudng Son, dang dinh ddc trung cho cac khu vyc thugc sudn Tdy Trudng Son ma nguydn nhan la tdc ddng cua dia hinh vd hodn luu quyen Vd cac chi tieu phan loai ban ban Sy keo dai ban hdn theo thdi gian dugc xdc dinb theo lugng mua theo Brunov, Henry, Cole, Bates, va Vien Khi tugng Thiiy van [2] nhu sau: - Tudn ban: lugng mua tuan khdng qua Smm Theo thdng Id, tudn la 10 ngdy 20 ddu ciia thdng va 10 hoac 11 ngdy cudi thdng, cd la hode ddi vdi thang Han hdn mgt tuan nao dd sd 36 tuan ciia ca nam la lugng mua tudn khdng qud Tieu chudn ban cua lugng mua tudn 5mm - Dgt ban: it nhdt 20 ngdy lien tyc lugng mua khdng qua 10mm, dd mua nhidu nhat khdng qud mm; - Thang ban- Lugng mua thang khdng qud 30mm (vao cac thdng miia khd) va khdng qud 50mm (cdc thang miia mua), - Han miia: lugng mua cua mgt so thdng lidn tuc dugc diing dd xdc dinh ban cd xdy vdo thdi ky hay khdng Ndu tdng lugng mua thdng miia khd hoac miia it mua nhd ban 60mm ho$c tdng lugng mua thdng miia mua lien tuc nhd hon 100mm thi cd ban xay vao thdi ky dd, tiic la ddi vdi Quang Tri: (1) Neu tdng lugng mua ba thang I -3 hoac 2-4 hoac 3-5 hoac 4-6 hode 5-7 nhd ban 60mm thi cd ban xay miia dd; (2) Neu tdng lugng mua hai thang 8-9 hode 9-10, 10-11 hoac 11-12 nhd ban 100mm thi cd ban xdy miia dd Cdc chi tieu khd dm xdc dinh han tuong cd the la: chi sd dm Lang (1913); chi sd dm Koppen (1918); chi sd dm De Martonne (1926); chi sd dm Reidel (1920), chi sd dm Angstrem (1936); chi sd dm Selianinov (1948); chi sd khd ban; chi sd khd han tich luy; chi sd mCia tdng quat, Han cd thd dugc phan theo cdc chi sd lugng mua tich luy nhu sau [2]: - Han xdy tren 21 ngdy lugng mua khdng vugt qua 30% lugng mua ciing thdi ky - Nam han cd lugng mua khdng qua 75% lugng mua tnmg binh nam; thdng ban cd lugng mua khdng qud 50% lugng mua trung binh thdng - Chi sd khd han cdc thang vd nam [2]: E Kl — — dd Et: Lugng bdc hai Piche 1,0 < K A 8 10 23 181 4.3 Thdng hgn Dd tien hanh phdo tich thdng ke cdc thang h^n thdi ky 1985-2012 theo sd lidu mua tai fram Ddng Hd, Lugng mua trung bmh thdng thdi ky ndy thd hi^n tren hinh va neu tinh theo lugng mua trung binh thdng thi mua mua t^i ddy la cac thdng 8-12 vd cdc thdng mda khd Id 1-7 TliftllrtlS 1400 i • Min 1 Tir sd lieu bdng 4, cd thd thdy ddi vdi Qudng Tri hdu nhu h^n miia chi xay miia khd (chi ridng nam 2006 Id ban todn nam) vdi tan sudt 17,9% (100 nam xay khodng 18 ldn) tai Quang Trj far nam 1985 den ndm 2012 • Max \ j SCO 4.4 Hgn miia Bang Cac mCia han co han xay miia T S-IOII KTB - Tdn suat ban thdng h^n cdc thdng ca nam Id 12,2% H^n han miia kho Han h^n mCia mira ll (trortg cac lhang) (Irong cdc t h ^ g ) Ji 1 *" ; -1 ™^n VDI IX X tl XI XD 2002 Hinh L u o n g m u a thang TB, Max va Min 2006 th&i Icy 1985-2012 T6ng c^ng D I nghien cuu su bien ddi ciia h^n hdn ta thudng tip trung vdo hai d^c trung co ban dd Id tdn suat han thang vd sd thdng ban ndm {bang 3) Nhu vay tdn suat ban thang nhu sau: 4.5 Hgn tinh theo chi so lu^g ehi so kho hgn mua tich ISy vd De so sanh da tinh toan h^in hdn theo cdc sd Bdng Cac thang han tho-i ky 1985 - 2012 Thdng mCia Thing mtia ThSng mCia ThSng mCia kha hgn mi/a hgn kh6 hgn mira hgn (mira (mua (mira (mua