8/7/2019 nh gi gi tr mi trng

1/5

Mt s phng php thng c s dng trong kinh t mi trng nh gi gi tr mi trng

nh gi cc gi tr mi trng, cc nh kinh t s dng phng php s cp vth cp. Phng php s cp cn phi c s thu thp v x l s liu da trn cc m

hnh. Phng php ny bao gm: Phng php chi ph y t, phng php nh gihng th, phng php nh gi ngu nhin, phng php chi ph du lch, Phngphp th cp da vo kt qu nghin cu t phng php s cp, xc nh hoc hiuchnh hoc thay i cc thng s t kt qu nghin cu. Phng php ny c Phngphp chuyn giao gi tr

1. Phng php nh gi s cpC s nh gi chnh l gi tr sn lng chi tr (WTP- Willing to pay) ca c nhn

cho nhng thit hi mi trng, ngn chn thit hi mi trng hoc nhng li ch mi

trng nhn cC nhiu phng php khc nhau c th c s dng trong nh gi kinh t cc tcng mi trng. Cc phng php c th c phn nhm thnh hai phm tr khi qutnh sau: (theo Turner, Pearce, and Bateman, 1994)

* Cc phng php khng dng ng cuPhng php ny khng th cung cp nhng thng tin nh gi v cc o lng

phc li thc. Tuy nhin, phng php ny l cng c hu ch thm nh chi ph, lich ca cc da n, chnh sch.

- Phng php thay i nng sut(Changes in Productivity): c s dng khi c

nhng thay i sn lng do tc ng ca mi trng xc nh gi tr kinh t ca sthay i (v d: gim sn lng ma v hay nng sut nh bt c) Nu tc ng mitrng c nh hng bt li ti sn lng, gi tr sn lng gim l chi ph i vi x hi.Ngc li, nu tc ng mi trng c nh hng tch cc ti sn lng (v d, hn chxi mn t hay ci thin cht lng nc) th gi tr sn lng tng l li ch cho x hi.Phng php ny c tin hnh nh sau: thit lp mi tng quan gia cc tc ng mitrng v mc thay i v sn lng. Mi tng quan ny ny c gi l hm phn ngtheo liu lng (dose-response function). Hm phn ng theo liu lng thit lp mi

quan h gia thay i v cht lng mi trng v nh hng ca n ti sn lng. Vd, hm phn ng theo liu lng c th cho thy vi 1% lp t trn cng b mt i, snlng s gim 5%/ha; hay hm phn ng theo liu lng c th thit lp mi tng quangia nhim nc vi sn lng c, gia mc lng ng trm tch trong h cha ncvi sn lng in. Khi mc thay i v sn lng c xc nh, s dng gi thtrng c s hiu chnh (gi bng/gi m - shadow price) (gi c s iu chnh vi

8/7/2019 nh gi gi tr mi trng

2/5

thu, tr cp,nu c) c s dng c tnh gi tr kinh t ca s thay i v snlng .

Phng php thay i nng sut c th p dng trong trng hp tng quan giacc tc ng mi trng v nng sut c th xc nh c. Phng php ny c u iml c th xc nh c trc tip gi tr kinh t ca s thay i, da trn gi v cc mc

sn lng c th quan st c trn th trng.Mt kh khn ln nht ca phng php ny l vic xc nh mi tng quan ny.

L do ch: Nng sut khng ch ph thuc vo cht lng mi trng hay khi lngti nguyn, m cn ph thuc vo nhiu bin s khc. V d, lng ma, k thut canhtc, phn bn, ging, Do , c th s khng d dng khi thit lp mi quan h giami trng v nng sut trong mi tnh hung.

Tuy nhin, nu xc nh c hm phn ng theo liu lng (v d, xc nh hmny bng cch k tha kt qu t cc nghin cu c trc) th phng php thay i nngsut c th cho ta cc kt qu nh gi kinh t hp l vi chi ph v thi gian ti thiu.

- Phng php chi ph thay th (Substitue Cost Method): khi con ngi chu tcng bt li trc tip t vic cht lng mi trng b suy gim, con ngi s dng mts bin php nhm loi b nhng tc ng bt li .

V d, trong trng hp nhim ting n, dn c hai bn ng cao tc c th lpknh cch m lm gim ting n. T , ngi ta tm ra mt phng php nh gikinh t i vi tc ng mi trng pht sinh do nhim ting n. Phng php ny cth thc hin n gin bng cch nh gi xem cn phi bao nhiu chi ph duy tr syn tnh. Phng php ny c thc hin nh sau: Ban u, c tnh s lng cc yu t

u vo cn thit c s dng b p nh hng ca cc tc ng mi trng. Sau, xc nh gi th trng c hiu chnh ca cc yu t u vo (tc l gi saukhi loi tr cc khon tr cp v thu, nu c). Tip theo, xc nh t l thay th kthut gia cht lng mi trng vi hng ho thay th. V cui cng l c tnh gi trca hng ho mi trng

Phng php ny c th p dng trong mt mt s tnh hung nh: tc ng ca nhim khng kh c nh hng ti c s h tng nh cu ng v nh ca. Trong trnghp nhim mi trng khng kh nghim trng, nh ca v cu ng cn phi cbo tr v sa cha thng xuyn hn. Chi ph cho vic bo tr v sa cha l mt phntrong nh gi kinh t i vi nhim khng kh.

- Phng php chi ph phng nga (Preventive Cost Method): trong nhiu trnghp, ngi ta phi b nhiu tin trnh cc thit hi c th nhn thy c. V d, ungnc ng chai, mua bnh lc nc trnh mc bnh kit l; ngi nng dn vng tthp chu ph tn trnh xi mn lm thit hi ma mng. Khi con ngi sn lng trtin nhm chng li nhng nh hng c th xy ra khi mi trng suy thoi, nhng chiph ny c th c s dng lm c s tnh ton cc ph tn do nh hng mi trng gy

8/7/2019 nh gi gi tr mi trng

3/5

ra. Cc chi ph phng nga thng l ch s chi ph nh hn chi ph thc (nu xy ra), vcc chi phng nga bao gi cng b hn ch bi mc thu nhp

- Phng php chi ph y t (Cost of illness) Trong nhiu trng hp, thay i vcht lng mi trng c nh hng ti sc kho ca con ngi, nh hng ny c thdn ti nhng hu qu lm pht sinh chi ph. Cc chi ph m c nhn b nh hng phi

chu nh chi ph y t, chi ph chm sc sc kho, chi ph do ngh vic, nng sut lao nggim trong nhng ngy m. Khi cc c nhn phi tr tin vin ph, tin thuc v cckhon chi ph khc cha bnh, cc khon chi ph ny c th c s dng lm c sc tnh nh hng bt li v tnh trng sc kho do s suy gim cht lng mi trnggy ra.

Cng ging nh i vi phng php thay i nng sut, phng php ny i hivic xc lp mi tng quan gia tc ng mi trng v thay i tnh trng sc khe.Mi tng quan ny cng c gi l hm phn ng theo liu lng. Tuy nhin, trongtrng hp ny, hm thit lp mi quan h gia cht lng mi trng v mc phtsinh bnh tt. V d, s lng mc bnh hen suyn do cht lng khng kh xu gy ra,hay s lng mc bnh ng rut do khng c s dng nc sch. Tip theo l ctnh chi ph pht sinh do sc kho b nh hng xu bi nhng thay i trong mi trng.

* Nhm cc phng php dng ng cu- Phng php o lng mc tho dng (Hedonic Pricing Method): Phng php

ny cho bit, gi ca mt s mt hng (v d, ti sn, nh ca bay bt ng sn khc) cth b nh hng bi cht lng mi trng. Mt khu t bi rc s c gi thp hn khut khng c bi rc gn . Tng t, gi nh c th b nh hng bt li bi nhim

khng kh. Trong trng hp ny, s khc nhau gia gi cc ngi nh b nhim v nginh khng b nhim khng kh c th c ly lm c s nh gi kinh t i vi tcng ca nhim khng kh.

- Phng php chi ph du lch (Travel Cost Method):Phng php ny c s dng thng xuyn nht khi tin hnh nh gi kinh t

cc a im thng c du khch ti thm (cng vin, khu bo tn thin nhin, bibin,). Trong nhng trng hp nh vy, gi v vo ca ti thm khu cng vin,khu bo tn hay bi bin khng th l c s ng nh gi vic du khch c sn lngchi tr n thm cng vin, khu bo tn hay bi bin hay khng v gi v ny thngrt r. Tuy nhin, c th p dng tng s chi ph m ngi du lch sn sng tr cho cchuyn du lch c ti cng vin, khu bo tn hay bi bin lm c s cho vic nhgi. Phng php ny i hi phi c iu tra quy m rng v c nhng phn tch thngk phc tp

- Phng php nh gi ngu nhin (Contingent Value Method). Phng php nycng c thc hin bng cch iu tra, lp phiu cu hi xem xt thi ca ngidn phn ng ra sao khi cht lng mi trng thay i v thm d xem h sn sng tr

8/7/2019 nh gi gi tr mi trng

4/5

bao nhiu trnh vic cht lng mi trng b suy gim. Phng php ny cng ihi phi tin hnh cc cuc iu tra, kho st v nhng phn tch thng k phc tp.

Trong cc phng php lit k trn, s phc tp ca cc phng php tng dn.Cc phng php khng s dng ng cu p dng n gin hn, cc phng php sdng ng cu phc tp hn. Chn hn, Phng php thay i nng sutp dng kh

d dng v c s dng nh gi kinh t i vi nhng nh hng lm gim nngsut do tc ng mi trng bt li (v d, nhim nc, khng kh hay xi mn t)Ngoi ra, c cc phng php khc nh Phng php chi ph y t, Phng php chi phthay th,cng l nhng phng php thng c p dng, v khng kh lm v mtk thut. Phng php khc kh hn, kh phc tp, l phng php nh gi ngu nhin,ch nn p dng khi c nng lc chuyn mn.

Ngoi cc phng php c lit k trn cn mt s cc phng php khc cngc s dng nh gi kinh t cc tc ng mi trng nh Phng php vn nhnlc, Phng php chi ph c hi, Phng php tnh thit hi v thu nhp, M hnh lachn,

2. Phng php nh gi th cpPhng php chuyn giao gi tr/li ch (Benefit/Value Transfer Method): Chuyn

gi tr c nh gi t mt nghin cu thc hin mt ni no (study site) nmt a im khc (policy site). Do cn c kt qu thng tin nh gi v do thi gian v shn ch v ngun lc khng th thc hin c vic nh gi. C ba cch thc hinvic chuyn giao gi tr

- Chuyn giao gi tr WTP trung bnh (ly kt qu c nh gi t im nghin

cu)- Chuyn giao cc gi tr WTP hiu chnh ( iu chnh kt qu nh gi t im

nghin cu do s khc nhau v thu nhp, gio dc,)- Chuyn giao hm s (ly hm s c lng c t im nghin cu hoc hm

s chung thu c t kt qu c lng cc hm s ca cc im nghin cu khc nhau)C nhiu cch khc nhau phn loi cc phng php, ngoi cch phn loi trn,

y l cch phn loi khcNhm phng php da trn hnh vi c thc: phng php da trc tip vo hnh

vi thc t ca ngi tiu dng hoc ngi sn xut (phng php chi ph y t, phngphp thay i sn lng, phng php chi ph du lch) v Nhm phng php da vohnh vi gi nh: phng php da vo hnh vi c gi nh v thng tin thu c quaiu tra (v khng th quan st c thc t) (phng php nh gi ngu nhin, m hnhla chn) V d, cn b k hoch ti mt a phng no phi quyt nh xem c nnu hay u t bao nhiu vo h thng ng cung cp nc. lm c vic ny, hphi s dng bng hi/phiu iu tra thu thp thng tin lin quan n s thch ca

8/7/2019 nh gi gi tr mi trng

5/5

ngi dn v nc sch. S dng cc phng php thc hin cch tip ny kh hnnhiu so vi phng php p dng cch tip cn da trn cc la chn c thc.

Tt c cc gi tr phi s dng ch c th c nh gi khng qua phiu iu tranhm thu thp thp thng tin t c nhn. Do , vic nh gi tc ng i vi cc gi trphi dng ca mi trng l vic lm rt kh.