CHAPTER 4
Purposes of Environmental Modelling
Envi,onmc.,"1 mod<llJ.J "'. be u"d for a numbo, of o;~r1appl!l1 bu' d,ff.".,
purpooe., 8<ooc", ,h.. "'pon ..mpl... wid. 'Pt'''um of p,,,co, .nd po"nt;.,l
.pplic"""'. of mod.Ulnl "choiqu,", i' may M c",iul
,;"rify the v.riou'
obj<'liv" of modcllin, "cd ..., ""d 'ke'oh in blood ou,1Ino ,h. f..,u". of c"h,
'0
'0
',1 MODELLJ;,;G AS A;'; EXTE;,;SIOS OF ISFOR.\IATlO:>
SYSTE~S
A' • bookil""nd to .o~ co,'I,,,,,,,,".,,1 p,obl.m. th. . . . I".dy "I", a
oon.iderobie body "f mf"rma""n, 10 or<ltr ,hal a pr<>bl.m lHr d.fm.d a.d .noly ..d.
•nd • wiubl. wlu,;"" oou&l>'. i' I. d.""blc ,h .. "i"iog. ,,1,,'2Il' inf",m"i". bc
ctill:«d .. far .. poo<iblc, Thi. 1cJ",,,,'ledre Ih"uld include. full ducnption "f ,h.
')'''c", i. qu,,'ion. dClOnplion' of ,h. beh.vK>n, of ."aloJ<'u, ,ymm, in the po" .
• nd of ,h. fao'oTl
,ymm,; d.lOription. of 'hc m"ho.lum i""Iv,d
In the dyn.mie. "f the ,y".m• •nd the M" inf"rmation "b"ln.blt to permi'
fOI<,.."n. of fu'uI< ch'I\i<' 10 I<1.;'2Il' .xttmal foo,on,
In m.ny e
mc,h of ,hi. informllion m.y hI" b•." ",,,,,mubled in >Om<
<><poized
nCt _ ci'her in • form ".,j.bl. by' thc hum•••y,c. '" onc di,ectly
"oc."bl. ,,, thc oompc'''. Th, inform.,ion i' likely to ,"c1ud' taW da,. - ,h•
...ults "f ao,c.1 ob ..".ti"n••nd 'u,'.-ey' m.d, of Ihis .nd ,imi;", <yll.m, in ,h.
p.., . •nd ... ""ioal ,,,,,,m.,,u of ,"rioU' "''''. ,u,h u mun•. lotll,. Ind
some of .,hkh
"bul"IQI\'. 11 "'ill .1", inclod. ,he ...uI" of ""i"i,iIi .niliy
mIl' lHr pe,f"rmed ""~' when Ihe .pecific n«eli of th. p
n' .nl'ironmen,,1
po-obl.", become ,I.. ,
Th••lmul.,ion model i"el( can M "prded u. put of 'he b"""ound data on
,h. 'l~ ..m. ,ond.n.iol .. I"in, knowltd,. of 'he "'uo'u,, Ind dynlmio. of
po-<x...... in VI orpnizcd .nd p..'i.. form. Th. ,ncl" ob1lintd by u.. of 'h.
modcl a", .100
m",h 0 pall
the dl.. ,y".m u 'h. original ob.. ",ed do.. on
which ,he model i. h•..-d. or .nj' quan"'i.. d.rived f,om lb.m by
.n.ll'i',
.rr"'in. ,n"",
as
"r
It.,I.",,1
4,1 MODElLl:>G I' E;,;V1RO;,;J,tE:>'J AL ),tA-'AGE\IE:>,. A:--D
DECISrO',.IIAKISG
Eo,·ll""m.ntal d'dsion' ue m.d. at .ari"u, 101'01. Th... begin ""i,h lh.
individu.1 ",·ho. on 'h, 'pur of the mom.nt. may d"td, ,,, thr"w hi' eigor."c but!
O\It of tho Oar "'",dO"" In"'><1 of puttm, i' in thc uh-,uv _ a dtclsion which may
..·.n ,..ull in lh' dtl,ruction of l I.rlll' Uti ef r""I1. At oth., 1...10. lb.
indu.tri.li" deotdinl '0 in".n a p"cipitalOf in hi< ,",0"·"00', the rcponal
"
"
COU""~
d,ddinll '0 '<align. road. lh, lI"",mm,nt d.cidiJll 10 pormi' nilh" by
.upo,..,.,i<; alrc .. ft, 01 ,he inler-tO"ermenlOl body cleoidJ"1 '0 imp"" limit< on
wh.l. <>tell.. .11 ore m.ld"l dod,ion. whioh ~'ill h.v, >orne ,ff••, on til.
toW""me"t.
Any dte;."", ;0"<>11'" • chol,. ""''''no .. Ie." two poa.ibl. """ .... of
..tion - ","n if one of th,m m.y be 10 ta~. no .«ion. which" il><lf. decision.
The cOfI>eqU<nc" of Nch of the p<»>ibl. cou",. of action n.ed '0 b. fo", ...n in
'hot the moll .ppr""rla'. ,hoi« l>e m.d•. If the d.<;ili<>n-mak..., obj«h.'•
ord.,
•"oI"':lIly f.Olort. of 'he "".ironm.nt _ to unpr".... th.m, to maiotoin 'hom. ot
nUllo perml' th'm 'n d..,ri"ro .. boyond ''',robl. lomit> h••""mdi"lIly n«d. ,,,
be .bI. to for''''' th. po.>ible .,..i",nmen,>I dr.e" of ,h. nn"o' «><I,... of
"non open 10 hIm, H. mo", .1<0 l>e .wm of 'oy other df.m(.c<>nomi<, 1OCi.1.
politic.al. <tc.) whIch mO" b< Itl...nt '0 hi> obI''''''''
,ff"" ...
En.irOllmenul
oft.n I... ",·.II.<Jefio.d .nd ulUall~' much more
d,fficult '0 f"rt_ th", 'h, ,ntrn.d"" .conom" o<"'''q",n"" of p,opo«<l '"u"',
of lO'iOf'. TIli' mak.. i' pattkul"ly diffi,ult lor ,h. dOCl.ioo-m.k", 'veO ""hoo
fully II...... of the poo,;bl. import."", of 'ovi,,'nrn'o,,1 o[f."". to "ke 'hom into
.«<>Un, .doq ...t<Ij", A first stOp 'ow>rd. " ..nJ 'oVlfo"""'n"l ,ff.. " .ppropnol<
",..,th' with o'h" '00"'1"'0= of 'h, d.",,;"n, "ken i. '0 doftn,. as Kcurat,ly as
I'<"'iolo, 'hoo< p,",o''''1 off,.......h"'h would O. r<prd.d ....I...nt. fbi, ;,
on "",olt.1 ,rep in the .ppb'"ioo of 'y",m, ,0.1,,;•• 'nd an import.nt
prehmina,y '0 the "'" of ..mulation mod,"rn,
A "hoi'" bet,...," ,h. ",riou, po..ibl, deci"on, molt be b''''d 00 predi"lion, of
th, la.ly «lutie of ,,·.n" lollow,oJ ..d, Gi"n 'he'" prod"'tton•. 'he d.m;"n"
maker comp".,. for a numbe' of ..,ilbl" io tho ,~",m, ,h. valu .. ",h"h ore
i'koly to ".IIl, rf h. mak" thl< 0' thlt ohoieo. Vor}' of,,". prediction of <h' "",I"
of differ.o' man,,.m.n, "ra"Ii" i. p""I,' int"i,,.. 'h' deci.ion-maker hlm"lf
make' ••u..... in ....hi,h hi' "n".1 pr...-io\I' uperi<neo In "m,i" ..'""ioo, plo)" •
rol•. often l",.l~· ,ub«,,,,don,, If • "mul.li"" moo.1 11 u"d. hov'"..r,
th, pred,"'''' p'",,""" on ""hi"h decision, at< ba..d ,on be mad•• ~pli'lt.all the
rI'IOI' ,,1""0' kn",,·ledg. of ,II< .y."m "on b< in'u't'O',"d. ,nd 'bu, ,h.
predi,tioo. be,,"no mu.:b more objecti .. ,h.n purely intuitive g"'....,
A "mullli"" mod,l u«d in 'hIS w.}' oun""u'<I • '''oden'''rion of e~i>unl
I:nowled,.. provid,ng ,ho decision-m,ker "'''h pred"t;"n, ....hkb <In holp him '0
make an ,"""i~'o' ,hOI'" be''''''''' dirr"""
and "hklt he ,-.n u" to
modify hi. owo ,"'ui".. 'houth' proce..... Wh,,, b"'kvound knowl'dg< ;,
"'''''y. bow"". "p<",n<o 'od in'ui,i"" m,~ ",,".um" b, a, d'p<ridable. ,rid a
fom\al simul,u"" mod.1 m.y provido • f.1« 'nd possibly h.""ful I..linl of
",urlly,
In 'h, "al "'·ulid. dec"ioI" , . . .I...... ~. mad. in ,h. he< of un"'''.ltIl~'
uncert.ln,y .1>0<>, 'h, fu'u" coo", of un«>rl"nUabl. ""'''. and un,,"a;n,,· ,n
on'-' kft ...... led,. of the .)'".m a. H no'" "i,,~ Thu" predio",,". are m01' u..rul to
,h. d"iiion·""k" ,i 'b.; lIk, thi, uneort.mtd"," "mun' for in,"no<, by 'h'
uk,,,, the f""" of. probabili'y d""ibUtl<>n fur .. cb .ari.ole .. ,her ,han a
lingl, "p«'ed "Iu•. Th. d"iliolt-m.k" can ,h.n ~ "gil, the p=;bl. uutcOITtr' _
.00II .nd bod - of ..ch deci.i"" h. might mako "ith ;ts pTob.bUi"· fbu" th.
"""t useful mod.l, fo' d"I"""<JTlbnl '" :Lk.l~ to ",,,orpor,,. """has",
.1.menl1••nd should pr",·Ld.....ith ..cb prediction.n n,di"uoo 01 in uneo".lnly.
'''''qi...
""'pu'
"
Simulatlon • .,e moslli~.ly 10 l>< nltful to,.nd uoed 0;, t~< d.dlion ....x.r l(h.
himself Ii.. bot" ,.. oI..d ,n th, mod.l-bu~dlnl proce ... ., I.." to the point of
iudlC.tinJ tho varl,b1e. he "',she, '" b. "I:"n ;oto •• ,,<,unt. If. furth." h. c.n '"
advance b< ,.,h., 'pe<Oifl" .INu' hi, ...10' .y".m _ not only name the ."Iabl...
bn' ind,• .,. ,Ii';, ",I..i,-o import.not _ 'h" model.an b" mort p",i..lj' .d'pt<d ,"
hi. 0,,«1•. and buill mor. «onomiruly ro< hi> pu,pos<'
A•• v.ri.nt of simul.lIon modelhllJ for deeision m.I:Lo,. on. m.~
P"""~ .pp",och, He,•. I human p"rlicipin, in""",,, ... "h the mod'l. .nd m.k"
d""i,;"." "' ....oon th, tim,
th" simul1tioo p,,,,,,ed'. lb. drem of the
seq.,.n" of deciSIon. h. ",.." on 'h" ultimo,. oule"","" m.; then h. ","died. TIi"
COIl,t;<",.. '" .... n.''''' of '''''ol.lion m<>d'ilin. by .UO\"in~ the us,,, of
leohn;q ... to i""<>due< ,he do<;,;oo-m.I<o" b.haYiouf ",t" ,he "muation p"""'''.
Th< ustr b..,,,n.. more 01"'" of ,he ,,,,,,ph of f",to,.. that "'ould bo ob.."",d
befor. ,noUr«> or. allocattd. H. pe,fo,rn, tht>t .llontron, '"d 'hen It" tho
In·built dyn'mlC< of th, und.,IY'"1 sunul.,ioo mod.1 ,orrv h,m '0 th. n." 1Imo
otep, Wh..e ........1 pl.y." ar. invol,td ..,par... ly. n,h "p"..,nting diff."nt
in'""". the adju1!rnent1 .nd ,ompromi.., "'hi<h ,..ult m.k. i' po.';ble 'o ..e
poli"o.l, IOCW. "'ooomic, ,.,hnol"l"'1. «0101""1. .nd P') dtologi<a1 conot,.in"
th.ar migl" oth"wi......pe .".nt;"" A 10<><1 ....mpl. of laming "' 'n .id to
d«i""".maki"1 i. til< "utrition,1 , ..... d...rib«l in S<<rion 9.6.
In pnn"pl•• tho "s< of ..muation m<>d<ilrnl ond pminl in ",Ivin, '"'''On""ntal problem, i' . . .pp'opri>t. to developing 'ountri" .. to tho« in .n
.d'-'fI<od ".g. of de"lop11l<nt, Th ••·,Iu••y"enu u..d in tho two """ m.y, of
'OU'
diff«, Th. d,,;';on-m.1«r rn tho d••,.lopirlj ,0U"t,,· i. likely to .mch
""'" iV" to «onomi, 1,O'O"h '"d to fO<><l ,upp!, .nd I,,, to poIlut;on .nd
,nvi'oo"..n,.1 .....n;t;... for in".ne<. How""r. th." i. "" ""'OIl o.hy 1imularion
mod,Urnl "nno' f""Ii ..,. the decision proco" the" ., much .. in • fully
induotriali..d count!)'.
.,.,,><1., •
'''P' ..
lim""",,"
4.3 IIODElU>.;G AS A RESEARCH TOOL
Genenlly 'pe.king.• mod,1 p,O"id... ,...,."h [001 'Or "pio'inl rho dedu<ti"
,,,,,oequtnc.. of any >ot 0' .."'mp"""" "p,ding the d)'n'mlC< of. ,y...m. TlIi'
..plo"tioo i' oft." the be" ~.~ of 'nting [h....ump"on. Th.i, <on""lu.non
m.y b< much ...i<, to "" .gain" .ctu.1 ob""',llon. th.n th••"umptlOn,
th.m..I"" In • compl'x 'Y'l<m it may b. [nlp"'~blt to ded"", rho con.. ~""nc<.
withoo[. ,;mul.""" mod'l.
Th, rompl.. 'Y'''m, in"olvtd in .nvir"""",",.1 p,obl.m. ofl.n «qu". on
int<rd'ociplin.!)' .pp,oa,h. II",t d"i,;oo pr""'..... ,00.. ;ng [0 rho .nli,on,",n,
rn'oI.. compl.x oon,Id.,,,[on, of m.n .nd tho >trueru« of """itty. 00 tho on<
h.nd, ."d of t~••urroundrng .. ",Id, on lh. "thor, T'adltron'lly. how."" th ..
t",o ,Id.. of tho probl.m h.v. b<tn OIudi.d as diff".nt l"'uP' of diS<.iplin
nd
.ppell ", be gov.mod by din'"nt t,-pe.o'I ...... Unl. ",• .,;on h.. bo.n ~"'o!<d
10 th. i"t"fac. bet ..·..n th'm
Imp'"",..! und.""nd,ng of p,"".... II th. Intorf"". lh. link, b",,·..n
p/'ly."'al and brologioal p,""'..... [n lh. '"";'0011l<n' on tho on. hond. ond th.
lnpoo .. "f man an~ hum~n SOl<"'I~ 1o m... p"":<"" on lh. olhcl - will «m.i"I~
imp'O"'c man, ability 10 connol 'he ,nvironnl<n" Effool1'·."udy of this intorf",
"
~'''.m
coli., of <0" .... fOT Ill< ,,,,,,,,,it_fit of i"rl<Td'""pli",,} t •• m•. A po"ly
oI>.."",m.1 .pp'oo,h 10 'he intera,lion. be''''•• n hum." wei«;, >rid tli,
ho~·.vtr _rn.y not I<.d "'Y fll. be,.u" ,h. Ob"'V;lbl. «>mbinllion.
t"vi,,,,,,,,,,",,
of bC101S lrt I limil<d .nd bi... J sample of ,Ii"", "h"1i "". "-ish.. '0 .tud~·, And
.,.nd ",,,,,,,,ioo
to •
b) <>p<r",..nt i. oft." h.r<lly pro.tIC.,I...-h... hum.on
""',,,;" III ;"Y"h.d.
Wh". <>r<rimt"" und" ,"""oll.d <ond,lIon .... Im~l. in 'h, ,..1"'Qlld .
• "",ulali"" mod,1 m,,fol ",b.",u" ,n SO for .. " ''''' be f<~lIded ...n
.deq""" repr<>rn","oo of re.lity_ It i, mwh m01< pra<ticabl•. for in","«, ,,,
study ,lit ;01<,0,1 mbili'y of m<>del 'y""'"
of the ".1 ."orld "pI..."t<d
by ,Ii... '}'Ito",.. It i, ,I", ...." '0 >ludy ,h, .. n~';"i'y of .y"tm. to •• "mol
innurnco, if tbe .,~1<m. <,n b< .. p"".n1<d b)' ".I~\-.lid",d """"I•.
'<><m' .,..
,Ii"" 'Ii"
The "",sibili'y of expori""'"""on on .n.i,onm.n,,1 probl.m. In ,h. ,..I world
.r< of"n limi"d by .,h,,,.1 <ooPl".1i"".: for in."no<. >lomi< .xplosion' <lin
h1ldly I>< lni,i."d pn"I~' •••n "p<ri""'nt. S,mulo ..d "p<n"",n" in • compo",
.r< ""'I"'t to no 'tlCh lom;""io", 'h.y." ""ri,,.d only by ,h. rompu .. ,
<opacity.nd tt"'" •• oil.bl., ThUl'''I'''rim.ntation u"n~ "mulotl"" mod.I...._ .
p,omisiuZ ....y of tad'Jln~ p,oI>I.",. >I ,h. in",f.o< I><, ... n human OOC\<t)' .nd the
.n,';,,,,,,,,,,n .. If mod.l. of tho physic.l .od biol~".1 .~ .1<m•• nd of ,he >OCIal and
""on"",le 'y".m. Or< .I,..dy "oil.hlo.•nd 'hoy h,," b.", .d"lu".ly "".d
sopo"1<ly', Ih.n urw:"u,nly i< limil.d
1M ,n1<"e'1o<I of ,h.", mod.I.,
of h.ndlmg th, p'occ .... in'oll'd may M "i.d 0'''. ond ,h.
Diff<r.n,
b<h• .,;ou, of tho mod.1 ,""'p1lod wHh th.lmo",n b.h,,;o", of "aJ.tif. 'y,.. m,. In
lhi' ""'y, by 'riol ond "''''', ...,M.. tory "p,<s<nlltion of ,h. inltlocuon, moy b.
'"oi""d.•nd onder1undina of th, p,ocess<' In,,,hod In<"a«<l. Thu•. 'im"!>'IO"
mod.l. CO" .."'
"h t""',. on ,h. on. h.nd 1o "" hypoth.... whrch h...
1>«n d•••loped by o,h
,n" ond, "" tho other. 1(' formul". hypolh .... OboUI
.)~,.m b<h"iou, ..hich ""gilt 01h.rwi.. not h". b••n ">n""i...d.
'0
""'y.
4A MODElll'G FOR AllOCATlO-': OF RESE>,RCll RESOLRCES
\l'h'" 0 11r~ ,...".;h p'oj«t in'ol'''. numb" of dl.p.,." .Iom.n".•o<h
• ""'"... .,.,d d.fmobl. ,ontribu,ion 10 an a«.pt<d <omm"" goat. it i.
of"n dim<uh for t.... t.....,h dir<cto, to jud~ Ih, app,op'''t. allo<>tio. of fund,
ond
1 .mool Ih.m. If. how...., •••imul.""" mudd uf Ill<: .yst.m UMer
study IS built. ,od in"oril<>''''' ,h. 1><" ......ina kno~ I<d&< (or info,mtd ~""ut.).
,I'i<n , objt<IM of I.... p,o!t<t e.n I>< d.fm.d ,n l<rm' of ""p,,,,,od ""o...I.d,,, of
Ih. I><h ou, of • I"". ,., of "",i.b"'.
Wi,hin th" .pp,oo<h.•"h ",..,ch .I.m.nl In Ih. PIOj<CI i, ..p,,,tod 10 "duc<
•• "ting "no<rl>in'y .bo"' ,h. P1lt of tho 'y",m to whi::h it I. odd"",.! i'l<lf;
this is. In fOCI. til< justifio>tion fn< I" ;nd'·"'n. On. m.y uk. fOf nch of Ih. Ore..
odd"...,j, whOl I. th' p"s<'" d.!". of "nw"inlY .nd to who, .x,.nl i. this
m.lkln~
1'<,,.,"••
.",,"'., ",""",", of
.<t,,,,,,,". 01"
<><.... if tho "~". ,. .1f••~ ... ~r
'.... b. . . . '01>.. 01. . .-1
10'1,,,,,,;". be,.·... ,n. <Ompo","' '''''''''''"", 'I1li. "p"...". ',""on H,oo,<ti<>l .ro~","
_h;<I, " .... '" r.I~'
",00<1 , ".''''ly
bY! • I.-li<>". ,h." .,... =
_ .. be to'"
"""
""0 ,."..,-io,".
..., ,.-I
.,1"","1 ,h.,. """,."ly.
_,.~
uneorta.nty· hk"ly 10 b< ",du,-.d .,. ,,,,ul, of th" T"'>reh propootd. On" m.y th.n
"'" Ill< mod.1
hat impro,·."",ot in ,h. pl<'dk'ion' "oold b. "'""c"'d if th.
protocI ""oro 'llCeo..foUy ''''''pl''''d. Su,h ",m '''''''''01< • form of ...",,""it'
"".lysi', .od " ....,,,h prio"'", <on ,h.n b• • Uouod in accord.nco wl1h lh"
..n,;li";I;- of p",d",tloo to Ih. ",,,,,,ltd '''0111 of Ih•• it<ln.,I,·. iin.. ufr ... "ch
.n....,.d. Such "n"""">, tom ",n .1", h"lp In i.np"",n~ lh. mod.1 it..li. b>
d""mlninl "'-h'eh por" of it .re critical .•nd ... h",. furlh" ,,'fo~ in d.",lopln~
til< modoll' hk.ly 10 b. ""-'$I i,o"rul
Moo.li;o, em .1", "'''' ....mh by Indle.,ln, ",·h"o. ",·h<n ••od h""
01>.. "..110." f01 • p.. "cul" pUrpoo< .-an b.., "" mad", A"'e,",,,,",,,.1 ob..".hoo.
fOf ;",tooc<. d<""nd' 011 'ho dl"obotloo of cloud and p,,,I,ul,,,, mmn.1 io 'h"
.. mosp/l<r" "mui,,;'m mod.Ii.n~ of "mo,ph"" con<ll"oo' can h.lp io d",,·
minlnl optimum 10<11;001 fo' ob..",.,ion•. P'Oi,arnm.. fn' .n"lron""'ol>l
"i01l," .... 11 " ,h. tim...od plleo' "
monitoriog ..I«lion of "'PO' of oll
"'hich th"y <hoold "" m.d. "an ILk i
COIV. ""fuIIUid",,,,, f,om S1mula,lon
mod"lIin..
'0 "''' ...
4S \IODltU'G IS mU(ATIO'
Stmol.,I01l mod.lllnl can .1'0 pl.y • u..ful f(~' io cou"', In lh. "nvl,onm.n,,1
scl"n".. io un"'","I" .nd ,<"hnle,1 eoll.~.., If lh. lo",",·,or ...Ish.. to ,/",... ,h.
"OO.n" how """' p.rtieu!>, cn,,, .. of .. lion ... 111 Imp,nS' Qn tho .n"i,,,,,mont .•
comP"'" '1ff,"1"lon p'"l!"mm. m.)' "'''y 'h< m"us. bot'" lh.n .ny pu.. ly·
.... ,b.1 .«wn, .....n if IU",lr""J '" i'h dl>lfOm. 'nd ITOph" Th"" ..",,<lolly tn" if
tho mod.1 p'"l!"m"" "'0 b< ..t up io su"h • .... y th>1 th. "ud.o, """ him"lf
modIfy ,h. inpu" and <ootrol' .nd ... th. ",,,,It,;n th. form oi mol'inll,"ph'of
,h. v,n.bl.. wi'h II.... Gamlog .ppruaoh.. - '("Tltllm., 1001'101 U.. of •
<ompu"" >Qmtl;mo. nul -.re .Irt.dy usod •• t<o~".ly In lh< cl>..."",m 10 h.,p
"ud,n" und."tand tho in""elloo of ,.ri.bl.. in .ov;100.... " ..1p,obl.m" ,nd th"
WlIj.. ln ..-hleh th<y can "" mfl",o",d by m,o'JO"",n'
ro' 'Il< """<...h,, ""-'r< .d'·.ncod "ud.n'. tl>< .. tu,1 bUlld'"l of mod.1> can
provid. v,luabl. ".inlol. lh. ,ompUl" m.k.. I"" d<m.T'Id, "" i" U..,.. fOf
cl,,,'y' .nd 10p,,01 thoolli'l. 'od .oy d",,,i.ocy;o thi' "p,d;, m",iI"",,y' "v.. ~d
FUTthom"'". ;0 p,"".mml"~ • model of.n .0";'on"",",.1 'l".m. th. "udont
will b< force<! 10 .. p" .. cl<1,ll ,II til< "Iatloo>bip, In th" 'Y".m. '0 m.k.
'.phdl , ..umph"n, ...h"" kn"wl«l;,,;' 'n.d"!ua.... nd '0 "'oid ,II <omf,,",n,
;·.guto..... ,
Th. «!u"tioo.1 ,..Iu. of ,Imul.. ioo mod.llin; con <'"nd "",,11 ""aid. lII"
duuoom. In ,,«nt }',"".'
public d.b... h" .ri.. o onr id"., iod""'d b~'
'ho publica""" of til< l"uJ" of •...orld mod. I,' by th. Club oi Ro"'" {M••dow',,,
11.• 19721 ""d o'h., 1'''''1''. Evon th""lIi' """" of th".. mod.l. h,,'< b<.n ...bj<et
to much <rI';"i,,". tl><y <.u1O'd ""opl. '0 think .hout th. I."~' cou'" of ch"".. in
,h. 'OI·llOfI"","' ...".n pro..o, ''''nds. Th. mod.1> d,d thl1 to .0 ..trot ..hi<h
purtly ""bal argu"",,,,, migl.. nOl h..·•• c<omp~sh.d. Th. ("Iub of R"",. "udy
jU" ",f.rred 10, how",,,, hOi .1<0 d.mo.,,,,,.d th1l, if mod.l, m u"d in publi"
e<!LlC1I;"". <om" in",""I"" "'""Id b. ,nclude<! 011 tho IITOI","OO. of mod.Uinl.od
the d~nim of un'litic~t Kctptlnce of Ih. results of utupolluon.
fl.,,,
4.6
.'IODELLI~
IS PL:BLlC"
'''FOR_'''''TlO~
A "1.,,,,1) n,w u" of >im"I"ioo moo,lling whkh "wid i-1in '" ,de< prom,n'nct
,h. fo,,,,e il iIwohd ,"'ilb eduCilion and mfommion ,xch2ngo in 'h, p"blic
arena_ Fo, inmo<t. <iti"n' ." c""'iug to npe<l .n",oom'fital imp..' "at,m,""
r<ga,dmg ","jo, "'OI~' ," ch.ns<, '0 policy I"h",. hO... ",<I. 'h, .m'~onm'olal
impact "at''''''n' bw,""" ,h, ,ubJ<" of litip"on. 'hm m.y l>e d,moul,;., in
d<mof"",t1ng ,he "han.. or modellinl ""'h' ""i,hin 'he f"""'wo,k of "1"
proc,du", (L.ou"ki. 19-4; OlOp1<f 5 of SCOPE. 1975a). and 'h, '"ul" may b'
I"hle to da'o""'" 2nd mi>r<p"..nlO'iou_
Simul.I,on moo'llio. cao .Iso pia)' • p," in IrnP"'vinl ,h. <omp."nc. of
'p<oial V""P' of de"i.ion·mak, ... A mod" <an "'""" ,h'm 'he ,,,ull$ofa<tion in
';' ... '''.n. surulaf '0 'h"'" which 'hey thtm.. I'n ha.. '0 conf"'1I1. and can 1how
to"'" of ,he "-.', m ""hkh ,he .ariou, p.", or 'h' ')"'rn ;n .. ,.. ' ond ml<rlock_
~od," c.n ,hu, 'nhan" 'h,I, app""ia1ion of th' dynamic, of <h' ') "'m. even
where <hey rna)' not ,h• .,.,h·" l>< in a I"""ion to apply. IimuLatloo-moo.Ujng
app'o><h di'ec'l)_
0", app,o.a,·h '" 'h" u" of mOO' Ii h.. b.,n <h'ouil' 'h, u" or,h. 1<,hn"", of
ga"';1liI'imul>t,on, An ... mpl, i' 'The P..,,,,,l"< G.m.· d,,·.,optd in AtlStrllia
(Ilenn.n <1 al.. 1973, T,oo"," " al .. 19741. Th, ·pl.y"· <al:" <h. 'ok of a
pasto"Ii" h,.edinl liv,stock in seml·.rid ooun",-, d'CLd,og on hI> Slocldng ra'..,
..,lil\£ .nd huy;olli,·.. ,oc~> and p;.inl Or I.,.,n! money .. a It,ul, of hi' d."sion,.
TIl< finallC;.1
ho..·....". ar< no' 'h, 001, on,,, h••1.., .... ,h. p..'u,..
d.,,';o''''nl 0' impro'i"! .. a ,,,"I, of,b. >lockin! "t" h. impo><' in "a",n, of
""'Ying rainf.ll. ,.d <h", h, can accumul.,. Hp<n.n", in pa>1o'al m,nall'm,n'
under v.ryina ,,,,,d,,,on' "'hich miil" .0,maU, "k. him maoy y.'" to '<:quilt
Th. pm< .... d«,I"I"d ,n 'l>< fo'm of. cornp"," program"" wh". ,b. play" >in
., a '"mi",1 and '",,,"",, wi'h III< ,ompu'" •• ,h. gam. p,outd" bu<" i••1so
...iI,bl, ... uhl. g'me '" ,m canl, .nd COllJl,....
G..,unS:>lmull1"," ,'.n "'tlinly l><lp <h. pi,)'" 1O und""'nd how ,.,iou,
r"lOIS may b< 'n<..,.ia"d "'ilh", a v'ry <omp~~ ')"1<m; but <hm i' '''''')'' ,h,
ri,k that <X'"~''' <on"d.n". m.y l>< placed In <h, ,,,,,," of gaming .",,,,,,,, ., in
other ,Imub,;"" app,o.a,·h.. , Apart f,om 'h. 'in1pHfi",lion, in••tUhl,. i""oou",d.
tho l><havi"", of ,h. ploy" ","y diff..- f,om <h., of ,he
po""n in. ,..Hir.
,,, ...,ion, TIi' ''''''....,. ;, diff.,.n< tnd hi' moli, "ion, ar. diff,,,.,
ill
,ff"".
':un.