NGHIEN c d u ANH HUdNG COA B I ^ N D 6 | K H I HAU O^N LUONG NIUA LUU VUC SONG SEDONE
vinvilay SAYAPHONE Bp Nong, Lam vd Ngu nghidp Ldo PGS.TS.NGUYEN HOANG SON, PGS.TS. L 4 VAN CHlN
Trudng Bgi hgc Thuy Ifri
Tom t i t : Trong nhiing nam gdn ddy, diin biin ciia khi hgu theo chiiu huang ci/c doan, ldm cho thien tai lu lut vd hgn hdn tdng cd tdn suit ldn cudng d0, Tuy nhiin, tren luu virc Sedone, Ldochra cd nghien cm ndo chi tiit vi Biin ddi khi hgu, DH lieu tii md hinh khi hdu todn cdu (GCMs) thuang cd do phdn gidi khong gian thdp (1,0 dd, 0,5 do, 0,25 do) vd thudrng rnanggid tri trung binh dgc trung cho cd viing rgng lon, vdi chgc nghin kirf, Trong khi do, cdc yiu td khi hdu thudng biin ddi mgnh theo khong gian vd thoi gian, dgc biet Id mua vd nhiet dg. NghiSn ciiu ndy sii dmg phuang phdp chi tiit hda thing ke di chi tiit hda cdc thdng sd khi hdu theo md hinh hdi quy da bien tuyen tinh. Kit qua tinh todn cho thdy.theo cdc kich bdn BDKH RCP 4,5 vd RCP 8,5lu(mg mua co xu thi gidm nhieu vdo cudi miia khd vd ddu miia mua gdy bdt lgi cho cdc nhu cdu diing nuac cua cdc ngdnh kinh tl Nghieu ciru ndy cung cdp sd li$u khi tugng cho viec tinh todn vd du bdo nhu cdu dilng nuac tren luu vuc sdng Sedone, Ldo ldm ca sd cho viec de xudt cdc dinh huang quy hoach vdphdt trien kinh te xa hgi choviing nghien ciru.
Tit khdaiLuu vuc sdng Sedone, bien ddi khi hgu, nhu cdu nu&c. SDSM
Abstract; In recent years,the climate changes in the extreme direction. Namely, precipitation has increased roughly in the rainy season and decreased in the dry season together with average temperature has increased. The climate change addes to more foods and droughts intense. However, in the Sedone Basin, Laos isn 't any detailed study on climate change. Climate change data from Global Climate Modeling (GCMs) are low spatial resolution (1.0 degrees, 0.5 degrees, 0.25 degrees), and the value is usually the average value for large area of several tens of thousands of square kilometers.
Whereas, the climatic factors often change significantly over time and space, especially in rainfalland temperature. This study used the statistical detailing method ofthe SDSM software to detail the statistics follow linear multivariate regression model The results showed that rainfall trends to decrease significantly at the end of dry season and early rait^ season and increases at the end of rainy season.
The change of rainfall under RCP 4.5 and RCP 8.5 scenarios trends to disadvantage for water demand of economic sectors and electricity generation, in late dry season and early rainy season, the rainfall trends to decrease sharply This study supply the meteorologicaldata to calculate and forecast water demand in the Sedone River basin, Lao PDR, which has regional planning and socio-economic development orientations for the investigated basin.
Key words: Sedone river basin, climate change, water demand SDSM
I. G i d l THIEU CHUNG mua tir thang 6 d^n thang 10, miia kho t i thang Luu vuc song Sedone gom 3 tinh la Salavan, 11 den thang 5 nim sau. T6ng luong mua tnmg Sekong va Champasak vcri t6ng dien tich tif binhnSm ciia luu vvc khoang 1700mm, trong nhien la 7.1S5km , trong do khoang 123.500 ha domCia mua chi^m 90% lugmg mua cS nam.
la dit nong nghiep, dan s6 345.896 nguoi. Nhi$t do trung binh nSm cOia luu vuc khoang Luu vyc song Sedon thupc viing khi hau 27°C va thay d6i khong nhieu giiia c4c thang nhi$t doi n6ng Im, v6i hai mua ro rjt la miia trong nSm. Do am cua luu vuc tuong doi thip 34 TAPCH(TAlNGUYENNl/ecs64-2017
• KHOA HQC CONG NGHE • vdi gia trj trung binh nam khodng 68%, thdi
gian ed df dm eao la nhihig thang mua mua va thdp vao thdi ky miia khd.
Hinh 1: Bdn dd luu vuc sdng Sedone
Sy bidn dOng vd mua lii didn bidn phdc t?p trong nhihig nam gdn day. Thang 3/2010 Bp Tai Nguydn va Mdi trudng ciia Lao da chinh thiic cdng bdChidn luac BDKH Qudc gia cua Lao.
Chidn lupc dd md td Ldo ciing Id mft qudc gia bi anh hudng nhidu bdi BDKH vd cdnh bao rdng, ddn cudi thd ky 21, nhiet dp trung binh cd thd tang thdm tu 2,5 - 4,2 dp C, kdm theo nhihig thay ddi ldn vd lupng mua ed nguy co gay ndn tinh trang lii lut va ban hdn vdi sdc tdn pha ldn.
6 cde khu vyc khac nhau cd the xudt hifn lupng mua ngdy di thudng khac nhau.
Cac ho?it dpng phdt tridn kinh te xa hpi tren pham vi toan cdu da va dang gdy sue ep ldn hf thdng khi hdu trdi ddt. Cdc ehdt thdi nhu CO2, CH4, N2O, HFCs, PFCs, SFe... dupe sdn sinh tir ho?t ddng cdng nghifp, ndng nghifp, giao thdng van tai vd nhiJng ngudn khdc rdi tich liiy lai, gay nen hidu ung nha kinh hay lam khi hau trai dat ndng len. Bien ddi khi hau dien ra tren pham vi toan cdu da vd dang la mdi quan tdm eua nhieu qude gia, nhidu nha khoa hpe trdn the gidi va
gdy tdc ddng ldn den tai nguyen nude.
Theo bao cao AR5, nhiet dp trungbinh toan cdu cd xu thd tdng ldn ro rft kd timhGng naml950, nhidu ky lyc thdi tiet vakhi hdu cye doan da dupe xac lap trong vaithap ky qua. Khi quyen va dai duong am len, lupng tuyet vd bdng giam, muc nude bientdng, ndng dp cac khi nha kinh tdng (IPCC, 2013). Luong mua cd xu thd tang d da phan cde khu vuc tren quy md todn cdu trong thdi ky 1901-2010. Trong dd, xu the tdng rd rang nhdt d cdc vung vT dp trung binh va cao; ngupc lai, nhieu khu vyc nhidt ddi cd xu thd gidm. Xu thd tang/gidm cua lupng mua phan anh ro ranghon trong giai doan 1951-2010 so vdi giai doan 1901-1950. Trong dd, xu the tdng rd rdng nhdt d khu vue Chdu My, Tdy Au, Uc;
xu thd gidm rd rang nhat d khu vyc Chau Phi va Trung Qudc.
Hifn nay dii lifu tir mo hinh khi hdu toan cau (GCMs) dang dupe dng dung rdng rdi trong cdc nghidn cdu vd BDKH. Tuy nhien, dii lifu nay thudng cd dp phdn gidi khdng gian thdp (1,0 dp, 0,5 dp, 0,25 dO)- D I cd the iing dungtrong thiiy van, tdi nguydn nude dde bift la eae luu vyc nhd thudng yeu cdu dii lifu cd dp phan giai khdng gian cao (mdt vdi kilomet) hodc dd lieu tai cac tram do. Vifc chi tidt hda cac kich ban BDKH cd thd sd dyng hai phuong phap Id phuong phdp chi tidt hda thdng kd vd ehi ti^t hda ddng lyc.
Uu, nhugc didm cda hai phuong phdp nay dd dupe Xu (1999), Wilby (2004), Fowler va nnk (2007) trinh bdy trong cde nghidn cuu trudc ddy.
Phuong phdp chi tiet hda thong kd thudng dupe sd dung dd chi tiet hda cde thdng sd khi h^u tai cdc trgm khi tupng. Trong dd, phuong phdp md hinh hdi quy tuyen tinh va phuong phap tgo cdc bien thdi tidt ngau nhidn thudng dupe sd dyng nhieu. Cae phuang phdp ndy don gidn, tinh todn nhanh vd mang lgi hifu qud cao (Wilks, 1992, 1999; Kim va nnk, 2007).
Cd rdt nhidu phuong phap vd phdn mdm cd thdchi tidt hda cae kich bdn BDKH nhu ASD (Automated Statistical Dovi'scaling), SDSM (Statistical Downscalmg Model), LARS-WG TAP CHf T A I NGUVeN Nl/OC 5(5 4-2017 35
(Stochastic Weather Gemerator). Trong dd, chi tidt boa thdng kd theo md hinh hdi quy da bidn tuyen tinh dupe sir dung rpng rai.
2. PHU'ONG PHAP NGHIEN ClTU Bai bao nghidn cuu su dung phuang phap chi tiet hda thdng kdtheo md hinh hdi quy da bien tuyen tinh, ung dung cho cac tram do mua tren khu vyc Lao.
Dii lieu mua su dung trong nghien cuu la gid tri lupng mua trung binh ngay cua edetram do mua. Trong dd,cae tram do mua cd sd lifu tu 25 nam (1990 - 2014).Cac ydu td phuc vu du bdo tren quy md ldn eua md hinh kbi hdu toan cau (CanESM2) - dupe tinh toan bdi CCCma (trung tdm md hinh va md phdng khi hdu Canada).Md hinh CanESM2 md phdng bien ddi khi hau dya trdn edc yeu td ddu vdo ciia bdo cdo danh gia lan thir 5 cua IPCC (AR5). Cdc ydu td dupe tinh toan dya tren kich ban phat thdi trung binh RCP 4.5 vd kich ban phat thai cao RCP 8.5, dii lifu phuc vy dy bdo dupe phdn tich dupe tdi midn phi tu trung tdm du bdo mdi trudng qudc gia cua Canada (website: http://wv^w.eccsn.ec.gc.ca/) vdi dii lieu tinh toan cho d ludi ed dp phdn giai 2.8125° tir nam 1961 - 2005, dupe coi la chuoi du lifu ca ban, dai didn eho khi hdu hien tai trong vide nghidn cuu vd bidn ddi khi hdu.
Phuang trinh hdi quy da bien chi tidt hoa lupng muaco dang nbu sau:
Y = aiXi-t- a2X2 + a3X3 + a4X4 + asXsH- a6X6 + avXv+e
Trong dd: cdc hf sd a; la cdc he so bidu thi dnh hudng cua gid tri Xj.
BB thyc hidn chi tidt hda cdc kich bdn BDKH theo phuang phap nay cac bidn X, dupe lya ehpn tu cac bien ddu ra cua md hinh khi hdu toan cdu (GCMs). Hf sd aidupc xac dinhtir cae phdn tich hdi quy vdi luang mua ngay thye do Y vd cae bien Xi.Phuong trinh hdi quy se dupe thidt lapcho mdi tram muadd tinh toan lupng mua ngay trong tuang lai.
Cdc budc chi tidt hda eae kjch ban BDKH nhu sau
1. Tai cde dil lifu cua md hinh khi h^u toan cdu (GCMs) cho khu vyc nghien cuu;
2. Lya chpn kich bdn BDKH phu hpp vdi vung nghien cuu;
3. Chpn cac tram mua cd sd lifu thyc do trong giai doan tu nam 1961-2005 phu hpp vdi kich ban nen;
4. Su dung tuong quan da bien, phan tich tuang quan givta cdc bidn cua md hinh khi hdu toan cdu (GCMs) va sd lifu mua thuc do tu dd lua ehpn cde bidn cd dnh budng ldn den lupng mua thuc do tai cdc tram co s6 lifu do mua;
5. Chpn cde bidn phu hap, xay dyng phuang trinh tuang quan da bidn dd tinh todn lupng mua ngay tir du: lieu eua md hinh khi hdu toan cau (GCMs);
6. Su dung phuang trinh tuang quan da bien dd tinh toan lupng mua ngdy cho ddn ndm 2099.
Sau khi tinh toan lupng mua tir md hinh khi hdu todn cdu (GCMs) cdn xem xet lupng mua tinh toan ed phu hop hay khdng (xem xet lupng mua nam, lupng mua thdng, miia mua, sd ngay mua trong ndm). Ndu kdt qud tinh toan ehua phii hpp vdi mua thyc do thi cdn hidu ehinh ve luang mua, sd ngay mua. Tir kdt qud tinh toan lupng mua ngdy nay, nghidn cuu phdn tich tinh todn luong mua ngay Idn nhdt trong ndm trong giai doan tir 2015-2099.
3. KET QUA NGHIEN CU*U
3.1. Lijra chpn cac bien dau vao cua mo hinh SDSM
Su dyng tuong quan da bidn, phdn tich tuong quan giira cdc bidn ciia md hinh khi hau toan cau (GCMs) vd sd lifu mua thye do tir do lua ehpn edc bidn ed anh hudng ldn ddn lupng mua thye do tai cae tram cd sd lifu do mua.
Nghien edu dd tinh tuang quan cua cdc yeu to khi tupng vdi lupng mua ngay eua cdc trgm mua nhuvan tdc gid tai muc 500 hPa, van toe gio tgi myc 850 hPa, van tdc gid tgi bd mat, do din tucmg ddi lai myc 500 hPa, dp dm tucmg ddi tai myc 850 hPa, dp dm tuong ddi bd m3t, dp am tuyf t ddi tai bd mat.
36 TAP CHf TAl NGUYgN Nl/OC S6 4-2017
• KHOA HQC CONG NGHE •
^ i ^ , (.*• . (^ . (?'- . i?"- ,),*• . u * . )?'• , { ? . 6 * ^ ( ^ ^ i ^ J^
Hinh 2: He so tuang quan giica luang mua cdc trgm luu vt^c sdng Sedone v&i edc yiu td du bdo
cita NCEP
3.2. Hifu chinh md hinh SDSM Nghidn cdu su dung d& lieu cua cdc tram Lao Ngam, Saravane, Pakse, Kongsedone, Nikom 34tu nam 1990 den 2005 tuong ung vdi dii lifu nen cua md hinh khi hdu tu ndm 1961 den 2005 de hifu chinh cde thong sd cua md hinh tinh todn. Kdt qud tinh toan cho thdy dii lifu mua cua cdc thdng tinh toan td phii hpp vdi dii lieu thyc do (Hinh 4). Md hinh su dung bp thdng sd ndy dd tinh toan cho cdc nam tir 2006- 2100.
Saravan
Khongxedon '^ ' ^
Lao ngam ^^^^^J*
<, Selabam * f Sekong Batlang
^ Paksong
K^l qua tinh toan va thu« do tir m6 hinh flting ke
Hinh 4: Kit qud tinh todn vd th^cc do tu md hinh thdng ke
3.3. K^t qud phan tich chi tiet hoa mua td*
md hinh SDSM
Kdt qua phdn tieh sy thay ddi lupng mua dudi tdc dpng cua BDKH theo bao cao ddnh gia ldn thd 5 ciia IPCC (AR5) cho thdy lupng mua ndm tai tram Saravane ed xu the gidm tii 7-11%.
Lupng mua vao eudi mua khd vao thang 4, thdng 5 gidm mgnh, trong khi dd lupng mua vdo cudi mua mua cd xu thd tdng len. Didu ndy gdy bdt loi cho phdt tridn kinh te xd hpi ndi chung va san xudt ndng nghifp ndi ridng khi cudi mua khd thi lupng mua lai gidm. Vd cudi mua mua lupng mua lai tang va ed kha nang lii xuat hien nhieu hon vao cudi miia.
CJ giai dogn 2017-2035 lupng mua mua khd gidm td 16-27% theo kich bdn RCP 4.5 vd giam tir 16-25% theo kjch ban RCP 8.5. Lupng mua mua mua cQng giam tir 6-9%, tuy nhien nhiing thang ddu mua mua lupng mua gidm mgnh, den cudi miia mua lupng mua lgi cd xu hudng tang len.
ThHv d^l lirg-fig mva gial iTof
AAUM
Hinh 3: Cdc trgm khi tufmg cita luu vifc sdng Sedone
Hinh 5: Thay ddi lugng mua giai dogn 2017-2035 trgm Saravane
TAPCH(TAlNGUYeNNl/(3CS(34-2017 37
Ddn giai doan 2046-2065 lupng mua mua khd giam tu 18-25% theokich bdn RCP 4.5 va gidm tirl5-21% theo kich bdn RCP 8.5 va mua mua luong mua cung ed xu the gidm. Giai doan 2080-2099 luong mua mua khd ed xu the gidm manh tu 16-25% theo kich bdn RCP 4.5 va kich ban RCP 8.5. Lupng mua co xu the giam nhidu vao cudi miia khd thdng 3-4 va dau mua mua vd tdng nhe vdo mua mua dac bidt tir thang 6-8.
Vide thay ddi lupng mua theo cdc kich ban BDKH RCP 4.5 va RCP 8.5 cd xu thd bdt loi cho cae nhu can dung nude vd phat difn khi cudi mua khd va ddu mua mua lupng mua Iai ed xu thd gidm manh.
Kdt qud phan tich BDKH tai tram Pakse cho thdy lupng mua nam cd xu the gidm tii 3- 5%.Giai doan 2017-2035 lupng mua miia khd giam 12% theo kjch bdn RCP 4.5 vd gidm 6%
theo kjch bdn RCP 8.5. Ddn giai doan 2046- 2065 lupng mua mua khd gidm tu 10-13% va den giai doan 2080-2099 lugng mua giam tir 9- 1 l%.Luang mua cd xu the giam nhieu vao eudi mua khd thang 4-5 va ddu mda mua va tang nhe vao cudi miia mua ddc bift tir thdng 9-10.
I Ttiay d&l l\nfna mira giai do^n 2017-2035 tr^m Pakse
theo kich ban RCP 4.5 vd tir 15-40% Iheokich ban RCP 8.5 ddn giai doan 2017-2035. Lupng muavS mua mua cd xu hudng tang td 3-5%.
Den giai doan 2046-2065 lupng mua giam tii 30-36% vao miia khd va tdng tir 3-5% vdo mua mua. Den giai doan 2080-2099 lupng mua vao miia khd giam 25-30% vao mua khd vd mfia mua tang tu 3-4%. Tuy nhidn, thay ddi lupng mua theo cac kich bdn BDKH RCP 4.5 vd RCP 8.5 cd xu thd bdt lai cho cdc nhu cdu dimg nude cua cdc nganh kinh td vd phdt difn khi cudi mua khd vd dau mua mua lupng mua lai c6 xu the giam manh.
Tliay d i l lirgng mira glal da^n 3017-2035 tram Li
u \ il I
Hinh 7: Thay ddi lugng mua giai dogn 2017- 2035 trgm Lao Ngam
J
Hinh 6: Thay ddi lugng mua giai dogn 2017- 2035 trgm Pakse
Hinh 8: Thay dot lugng mua giai dogn 2017- 2035 trgm Kongsedone Tai tram LaoNgam lugng mua nSmtheo Idch
ban RCP 4.5 co xu huong giam nhe tii 0-1%. Theo
kich ban phat thai cao RCP8.5 luong mua n t a Tai tram Kongsedone giai doan 2017 din 2035 tram Lao Ngam tang tir 0-1%. Tuy nhien, lugng lugng mua nam giam 0.6% 6 kich ban RCP 4.5 mua vao miia kho co xu huong giam tii 25-28% v4 giam 0.2% theo kich ban phat thai cao 38 TAPCH(TAlNGUYeNNUOCS64-2(
> K H O A H Q C C O N G N G H ? •
RCP8.5. Giai doan 2046-2065 lugng mua nam giam 1,8% theo kich ban RCP 4.5 va tSng 1%
theo kich ban RCP 8.5. Giai do?n 2080-2099 lugng mua nam tSng 0.4% theo kich b ^ RCP 4.5 va tang 1.5% theo kich ban RCP 8.5. Lugng mua miia kho giam manh tir 12-30%. Lugng mua miia mua tang tir 10-30% dac biet a cac thang cuoi mua mua.
Lugng mua nam tai tram Nikom 34 d8n nam 2035 theo kjch ban RCP 4.5 giam 12% va giam 13.5% theo kich ban RCP 8.5. DSn giai doan 2046-2065 giam 11,3% theo kich ban RCP 4.5 va 14,2% theo kich ban RCP 8.5. DSn giai doan 2080-2099 giam 11,5% theo kich bta RCP 4.5 va 12,3% theo kich ban RCP 8.5.
Giai doan 2017-2035 luong mua miia kh6 giam 3% theo kich ban RCP 4.5 con lugng mua miia mua Cling giam tCi 13-15%. Giai doan 2046-2065 va 2080-2099 CO lugng mua miia kho tang tir 1 - 3 % theo ca hai kich ban con lugng mua ve miia mua giam til 13-16%. Tuy nhien, lugng mua ve ddu miia mua giam ro ret va tang nhe vao cuoi miia mua
- ^ i
Hmh 9: Thay ddi lugng mua giai dogn 2017-2035 trgm Nikom 34
4. REIT L U ^ N
Nghien cuu da phan tich lya chpn dii lifu todn edu d^ tinh todn lupng mua ngay theo cde kich ban bidn ddi khi hau. Nghien cuu cung da phdn tich sy thay ddi vd lupng mua phan bd mua tren luu vyc sdng Sedone ttong cac giai dogn 2017- 2035,2046-2065 va giai doan 2080-2099.
Kdt qua tinh todn cho thdy, tgi cac trgm Lao Ngam, Saravane, Pakse, Kongsedone, Nikom 34
(hinh 3) lupng mua mua khd giam. Hau hdt cac tram cd luong mua miia mua giam, tuy nhidn cd trgm nhu tram Lao Ngam cd lupng mua tang vd miia mua.
Tgi cdc tram do mua da nghien cdu cho thdy khdng cd sy thay ddi vd thdi gian bdt ddu mua mua vd mua khd. Tuy nhidn lupng mua cd xu the giam nhidu vdo cudi mua khd thang 3-4 va ddu miia mua va tang nhe vdomua mua dde bift tir thang 6-8. Vide thay ddi lupng mua theo cac kich ban BDKH RCP 4.5 va RCP 8.5 cd xu thd bdt lpi cho cac nhu cdu dimg nude cua cac ng^nh kinh te va phdt didn khi eudi mua khd vd ddu miia mua lupng mua lai cd xu thd gidm manh.
Do hidn nay cd nhidu md hinh tinh toan nghien cdu vd BDKH, mdi md Wnh Igi cho cdc kdt qua khdc nhau vd BDKH trong tuong lai. De ed cdi nhin tdng quat han vd bien ddi lupng mua trdn khu vyc cdn nghidn ciru thdm cac md hinh BDKH todn cdu khae tren thd gidi.
TAI LIEU THAM KHAO 1. Bp Tai nguydn va mdi trudng, 20l6,Kich bdn biin ddi khi hdu nu&c biin ddng cho Vi$l Nam, Tr.96.
2. Wilks, D.S, 1992, Adapting stochastic weather generation algorithms for climate change studies. Climate Change 22, 67-84.
3. R.L.Wilby, C.W.Dawson, E.M.Barrow, 2001, SDSM- a decision support tool for the assessment of regional climate change impact.
Environmental Modelling & Software.
4. PauUn Coulibaly and Yonas B.Dibike, Downscaling precipitation and temporal neural networks, 2005, American meteorological society.
5. Trdn Thanh Xuan, Tran Thuc, Hodng Minh Tuydn, 2011, Tdc ddng eiia biin ddi khi hdu den tdi nguyen nu&c Viet Nam, Nhd xudt bdn khoa hpc-kythu^t, Tr.l 18-121...
Ngu&i phdn bi$n: PGS.TS Ngo Le Long Nhgn bdi: 28/8/2017
Phdn bi?n xong: 8/9/2017
TAP C H I T A I NGUVeN NLTOC S64-2017 39