N O T I C E 

THIS DOCUMENT HAS BEEN REPRODUCED FROM 

MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT 

CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED 

IN THE INTEREST OF MAKING AVAILABLE AS MUCH 

INFORMATION AS POSSIBLE 
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Ea/,-lOOQ3 

S.al-Annual Technical Report /1IA5,f--CR-17~P?" 

FEASIBILITY OF USING LANDSAT IMAGES OF VEGETATION COVER 

TO ESTIMATE EPPECTIVE HYDRAULIC PROPERTIES OF SOILS 

(E86-10003 11Sl-Ci-176266) fllSlBILl!r O~ 186-12739 

OSllfGL1IDSll' IlflGES 01 'EGI1'I1'I01 COYBR 1'0 BSil~A1'! BlFBCflV! 8rD~lOLIC fiOPERXIBS O~ 

SOILS Se.iaaaQal !echDical BepOEt, 1 leb •. - UDclas 

31 Jul •. 1985 (ftassachusetts last. of Tech.l G3/43 00003 

by V 

Peter S. Eagleson 

Edmund K. Turner Professor of Civil Engineering 

Massachusetts Institute of Technology 

Cambridge, Massachusetts 02139 

1 February, 1985 thro,~gh 31 July, 1985 

~,.,.~Ii§ .' .. , 

-""''''"~'.-.' . 
1 

TABLE Of CONTENTS 

Page 

T ABLE OF CONTENTS 1 

I NTiODUCT ION 2 

RESEARCH ACTIVITIES 3 

Visit to Goddar.d Space Flight Center 3 

Literature Review 4 

4 Vegetation Canopy and Soil Reflectance 

ieflectance from Natural Landscapes 5 

Summary of Literature ieview 10 

Formulation of Percent Canopy Cover Algorithms 10 

Empirical Approach 11 

Theoretical Approach 13 

Selection of Test Sites 14 

FUTURE RESEARCH 17 

REFEltENCES 18 
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INTRODUCTION 

Thi. r.port .u ... riz.. r •••• rch activ1ti.s conducted from February 

1. 1985 to July 31, 1985 and prell.1oary conclu.ion. r.gard1ng re •• arch 

obj.ctiv... Th. ov.,'all obj.ctivea 11 to det"rmin. the fea.1b1l1ty of 

u.ing Land.at data tt· •• U.at •• ffecUve hydraulic prop.rUe. of .01h. 

Th. general approach 11 to apply Eagl •• on'. "clll1atic-cU,IIlax" hypothesll 

(Eagl •• on, 1982) to natural wat.r-l1.1ted vegetation .y.te •• using canopy 

cover e.t1.at.d fro. Land.at data. 

Natural wat.r-l1I1it.~ .yate •• typically cons1.t Qf 1nhomogcneou~ 

vegetation canop1.. 1nter.per •• d w1th bare .011.. The ground reBolution 

as.oc1ated w1th on. pixel froll Land.at KSS (or TK) data 1. generally 

greater than the .cal. of the plant cat\opy or canopy clulters. Thul a 

.ethod for r •• olving p.rcent canopy cover at a .ubpixel level must fir.t 

be e.tabll.b.d before the Eagl •• on hypothesi. Is tel ted. 

Specific project objective. ate thuI, 

1. Evaluate the existing capability of defining vegetation canopy 

density fro. Landsat data with a relolution and accuracy sufficient for 

use in ter/ting the climatic-climax hypothesil of climate-loU-vegetation 

equl1.1briull. 

2. De.ign.the research needed to create the necessary capability If 

it il found (under Objective 1) to be deficient. 

3. Design the serie. of ftxperiments necessary to test the 

cliaatic-cli.ax hypothesis. 

One lIajor conclusion of the work to date Is that current methods 

for resolving lIixed pixels, which have been developed primarily for 

agricultural lands, have not been adequately tested on natural landscapes. 

IioiIfif=.,;....-.'-~.~...:...··~.'--;..J.:"~~:-~~·:-'~ .... ·'~"" ..... - .... _.....-________ ......... ""· ~("""'_"""""~~~_'*".y.tI1.~~ -...,. 

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Method. which r.quir. the identific.tion of tr.ining •• ~l •• c.n not b • 

••• 11y .ppli.d to n.tur.lly v.g.t.t.d .y.t ••• due to t~. inhomog.n.ity of 

the cover. 

Two for_l.Uon •• r. propo.od which .xt.nd .x18ting •• thod. of 

.n.lyzing mixed pixel. to n.tur.lly v.get.t~d l.nd.c.p... Th. fir.t •• thod 

involv •• u •• of the norm.liz.d veg.t.tion ind.x. Th ••• cond .ppro.ch 1 •• 

phy.ic.l .od.l b ••• d on r.di.tiv. tr.n.f.r principl... Both .. thod. will 

b •• nalyz.d for th.ir fe •• ibility on •• lect.d .it •• during the .econd h.lf 

of this r •••• rch proj.ct. 

IESEAICH ACTIVITIES 

The r.porting p.riod cover. the lnlti.tion of work on this topic. 

Accordingly, re.earch activiti.~ h.v. included • vi.lt to the Godd.rd Sp.c. 

Plight Cent.r, Gr.enb.lt, M.ryl.nd, compr.h.n.ive liter.tur. r.vl.w, the 

pr.lillin.ry forllul.Uon of .lgorithrl. to deterlline p.rcent canopy clov.r at 

a subplxel sc.le of resolution, and the .earch for .everal repr •• entatlve 

water.heds in which to conduct the research. Details of each of these 

activities are described below. 

V1alt to Goddard Space Plll~.t Center, Beltaville, Maryland 

lesearch commenced with a visit by the principal Investigator, 

. Profe.sor Peter S. Eagleson, and his assistant, Michael F. Jasin8kl, to the 

Earth Resources and Hydrological Science. Branches, Goddard Space Flight 

Center (GSPC) on January 31, 1985. The purpose of the visit was to 

familiarize the MIT researcher. with ongoing activities at GSPC and to 

discuss research goals with key GSPC personnal. Heetings wer.held with 

Dr. Vincent V. Salomonson, Dr. lobert Gurney, and Dr. Thomas J. Scnmugge, 

allong others. Image analy.18 of HSS data wa. demon.trated by Jalles 

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Oruby. During the .ft.rnoon, Prof.asor E.gl.son pre •• nt.d a s.minar on 

wat.r-limited equilibrium of lav.nn. v.get.tion .yetems, wo~ksupported 

und.r a prior NASA r ••• arch grant. 

Lit.r.tur. a.vi.w 

Ongoing literature revi.w h.s concentrated on ...... ing the curre,nt 

cap.bility of e.tim.ting percent canopy cover u.ing Landsat data. Curra~t 

techniques for cla •• ifying agricultural lands including those over mixedcrop typ.s have been reviewed. Th. reflect.nce proper tie. of vegatation 

canopie. and .oih in the visible and n.ar infrared range have been 

inv •• tlgat.d. This has required a review of the theoretical principle. of 

radiative transfer through leave., the atmosphere, and other media. 

V.getation Canopy and Soil aeflectanZ!. 

The reflectance of the visible and near infra-red range is well 

documented. Canopy reflectances are typically mQch less than those 

measured for individual leaves (Dickinson, 1983) due t9 the scattering 

properties of plant architecture and soil background. Colwell (1975) 

discussed the important parameters which influence canopy reflectance, 

including leaf hemispherical transmittance, leaf area and orientation, 

plant structure components, soil reflectance, solar zenith angle, look 

angle, and azimuth angle. Tucker et a1. (1917) found that the effect of 

underlying soil decreases as vegetation biomass increases. The results of 

numerous studies of plant and canopy reflectance are summarized in 

B.oaatlberg et ale (1983.), Smith (1983) and Hyers (1983). 

aadiative transfer formulas for homogeneous canopies have been 

developed in terms of the physical and optical pr~perties of the plant and 

background soil reflectance (Suits, 1972; for summary of other formulas see 
, 

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Smith, 1983). typically, homoseneoul canopies have been aodeled al a 

diffu.ins .ediu. with ablorbins and .catterins propertie.. Dick inIon 

(1983) applied tbe two-.tream approxi.ation for radiation tranlfer in the 

a~olphere (Meador et al., 1980) ~o plant canopie. e.ployinS the Leaf Area 

Index (LAI) a. a .ealure of the opti:al depth. 

The reflectivity of plant canopies i. hiShly wave1ensth dependent. 

It i. typically low in the vi.ible .pectrum «30%) and hiBb in the Dear 

infrared ranse (>50%). Kondratyev (1969) and Iqbal (1983) provide 

.u .. arie. ~f reflectances of various natural vesetation coverl. 

The Ipectral characteriaticI of bare loi11 have a110 been extenlive1y 

inveltisated, al lu •• arized by Heyer. (1983). Soil reflectance i. a function of color, mineral content, orsanic matter, particle .ize, texture, 

1I0isture content, and wave1ensth", SoU reflectance 11 generally le .. than 

30% and in(:;1'ealel linearly with wavG1ength OVer the ranse 0.4' - 1.0 II m. 

Wet 10UI exhibit lower reflectance than dry IUUS but senera11y ma.intain r. 

limi1ar linear behavior in reflectance ove~ that ranse (Tucker et a1., 

(1977). 

Reflectance from Natural Landi capel 

The reflectance from natural landscape. results from the complex 

interaction of light with the vesetation canopy and loi1 typel. The canopy 

alone ~ften consists of a mixture of varioul plant species of different 

slzel and architectures. Soil types can also vary over a short distance. 

The radiance observed by a Landsat sat~llite is a composite of those canopy 

and loil components which are subsequently scattered and attenuated by the 

atmosphere. 

The identification of landscapes which consist of several cover 

types is a common problem encountered by imase analysts. Both empirical 

5 

.r'.> __ 
c1 ••• ifl~~tion .ch •••••• ve11 •• .ore phy.lc.11y-b ••• d mod.l. h.ve be.n 

d.velop.d. althoush •• pirica1 •• thod •• r. the .o.t wid.ly u •• d .nd by far 

th. lIO.t lucc ... fu1 (E.t ••• t .1., 1983). Cl ... 1flc.tion method. h.v. 

be.n us.d in conjunction with tellpor..1 an.1y.,t. to t.k. full .dv.nt.s. of 

•••• onal v'S.t.tlon ch.ng •• (lob lnov. , 1981, ~i •• t .1., 1981; for ~u ... ry 

I.e E.t.s et .1., 1983). 

Cl ••• ificatlun of cropland ha. reli.d on varlou •• tatiltlcal 

c1u.t.rins alsorlth •• , .uch •• tho .. e u.ed in the Lar'se Area Crop InventorY 

Experiment 

(L~CIE) (Lennlnston et al., 1984, Amil Mt al., 1981). The.e method. 

gen.rally require the identification of training ... pl •• or pure pixel., 

i~ •• , th .... ociation of L.nd •• t ob.erv.t1on. with known tarset.. Each 

training •• mple conltlU of a IOU and canopy co.binat;~.on with a Ipectral 

re.pon.e r.pr ••• n~.tiv. of • larger .r.a. Thi. advantas. i. ulually not 

pre'ant when cl,"1fylng natur.l landlc.pel, lince mOlt targets pOllel' 

unique Ipectral char.cteri.tics. 

The follOWing .ectionl delcribe .everal techniques which have evolved 

for .n.lyzing non-uniformly vegetated landlcapel. 

Vegetation Indicel. Semi-.mpirical methods for reducing the amount 

of KSS data have led to the development of the vegetation index (VI). The 

ule of the VI for identifying vegetation.parameters hal received much 

. attention in the lalt few years. Perry et al. (1984) summarize the 

nu.eroul VI'I which have been proposed. A typical VI is a normalized ratio 

of the fom, 

VI • ala 'vIS 

'xa + 'vIS 

where ala and SyIS represent the surface albedo in the II and visible 

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r.nge •• recpectively. Low VI indic.te. l~w v.git.tion .mount. wh.r ••• high 

VI indic.te. eith.r high v.set.tion •• ount or high productivity (Curr.n8 

1980). S.ll.r. (1985) di.cu ••• d the function.l r.lation.hip b.twe.n 

norulizE"'d VI .nd •• v.r.l veget.tion p.r .••• t.u. including the Le.f Are. 

Ind.x (LAI). gr.enn •• I •• nd photo.ynth.tic r.t.. Tuck.r.t .1. (1983) 

corre1.t.d a nor.a1ized VI (co~4ut.d from NOAA'. AVHIR dat.) to .ctu.1 

biomel. obtained from field ,.-pling in a .emi-.rid reglon of Senegal. Welt 

Africa. However. much .c.tter of the data exilt.. Recant1y. the effect of 

.oil background on VI'I computed from hand-held or airborn. radio •• t.r data 

h •• b.en .v.luat.d (Elvidge et a1 •• 1985, Hu.t. et al •• 1985). 

While the functlon.lr.1ation,.hip b.twe.n the VI and .evera1 

v.getation para.et.rl ha. been qu.litatlv.l~'id.ntified, the quu.tlfication 

of the.e parueter. (baled on VI', computed using Land.at dota) b., 

attained only limited .ucc.... Additional relearch i. warranted in at at 

1ea.t two areal. Firlt, the functional re1ationlhip between the VI and 

percent canopy cover need. to be clearly eltablished. Secondly, the 

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u.efu1ne •• af the VI in analyzing natural landlcapel needs to be examined. 

Theoretical Hodel.. The prob1ftm of relo1ving a mixed-pixel has been 

approached by as.uming that ltl total .pectral response is a linear 

combination of the individua.1 .pectra1 respon.el of its componeuta (HcCloy, 

1980; Dozier, 1981; Ungar et al., 1981; Chhikara, 1984). HcCloy (1980) 

propo.ed that under conditionl of negligible canopy transmi8sion or 

multiple reflection, the re.pon.e proportion. of the varioul land cover. 

will c10lely approxiloate the phYlical proportions of e.ch type of cover. 

McCloy (1980) suggested that up to four sub-pixel categories be u.ed 
including thr •• l.v.l. of v.g.tation gr •• nn ••• cov.r and on •• oil 

backlround cov.r. 

Unlar .t al. (1981) r.port.d .ucc ••• ful d.lin.ation of for •• t canopy 

typ.. in Kain. u.ing a .t.ilar approach which th.y t.r-.d the "Fanning 

alloritba". Unlar.t al (1981) a •• u.ed that the total radianc. r.c.iv.d 

fro. a .~x.d pixel, ~. can b •• xpr •••• ~ 

\ ."\ + (1-") s,. (2) 

wh.r. 'A and s,. ar. the .n.rll •• r.ceiv.d in the A th band CrOll 

.ub-pixel .urfac •• l •• ent. A and B, r •• p.cUv.ly. Th. co.ff ici.nt" 11 the 

fract,ional ar.a occupi.d by cover typ~ A. Th. value" wa. d.t.nin.d by 

UGgar .t 81 (1981) by lIiniidzing the .t'ro"r b.tw.en ob •• tved aG! th.or.tical 

radianc ••• 

"Dozi.r (1981) also propo.ed a 8i_ilar _.thod using two infrared 

band. for differentlaUng radianttellperat"r. field, of sub-pixel spaUa1 

re'(/1utlon. Corrections for' atmospheric .ffecta w.re included. 

The thlloretlca1 nadir radiance ob •• rved by a ,atellite has 'been 

deriv.d by several author, (Dav. 1980, Otter_an et a1. 1979, 1980, and 

Otterman 1978, 1981) for a pure pixel in a background of different 

reflectivity. The nadir radianc. is expre.sed in terms of three 

component.. The direct b •• froll the object pixel which has been 

attenuated due to atmospheric effects, Ln~, il 

where l' • reflectivity of object pixel 

Gt • global surface irradiance on object pixel 

T • total vertical optical thickness. 

(3) 

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t' 

i' 

. The total optlc.l thicKne .. b •• u. of opUc.l thicKo ••••• due to R.ylelgh 

Icattarins by g •• IIOlecu1e., t R, end Hia .c.ttariog by .aroooll, t H. 

Au,ull1og • La.ba~t1.n lurf.ca, ~ha portion of diffu.e r.dianca fro. 

the .urroundln, vicinity which 1. Icattared to tha .atallite by tha 

at.o.~harlc coluan .bova tha objact pix_1 1. 

whar_ 

a • avarega r.:.1.ecthity of the .urrounding vicinity 

PR,PH • ph •• a function •••• ociatad with Rayleigh and aero.o1 

(Hia) .cattarlng, r.a.pactlvely 

• - ~anith raf1actlon angla. 

Fiu.lly, tha radiance Icattared fro. tha direct lolar beam back to the 

satellita is written 

~here 1I 0 • cos e CI 

eo· solal' zenith angle 

The total nadir radiance II the su. of equation. (3), (4) and (5). The 

amount of area to b~, considered in deter.inlng the average lurrounding 

(5) 

reflectlvltJ Is dilcussed by Otter.an et al. (1979). Otterman et al. (1980) 

reduced the above equaUon. to a sillpler fora in the ca •• of an opticaUt 

thl~ atmosphere. Otter.an (1981) also developed an expression for 

rsflectlon fro. sparsely vegetated solli In teras of a surface cover 

para.eter. While accounting for the shadowl~g effects of vegetation 
r 

cluap.. the for.u1atlon a •• u.e. that reflection from the top of the clumpe 

11 negligible. '1.'hu •• thil .ethod 11 not directly appU,c"l>le to the 

deter.inatlon of percent canopy cover. 

Su.a!1 of Literature aev.l..,. 

The liter.ature review ha. led ~o the following conc1u.lons regarding 

technique. available to e.ttaate canopy cover at a .ybpixe1 level of 

r .. olutiOD: 

1) Technique. for evaluatiDg aixad-pixe1. have focu.ed pr18arily on 

di.tIDgui.hing cropped land.. Ho.t technique. require the identlfic~tlon 

of trainin •• eaple., which prevent their app1icatioD to inhoao.eneou. 

canopie.. The application of the.e .ethod. to natural land.rape. ha. 

received very 1i.ited attent1~\~ and n~ed. to be developed further. 

2) Whllethe correlatioD Qf the V'I~ with .evera1 v"getattoll 

para.iter., .ucb a. bio.a'G or gr.enne •• , ha. demon.trated definite 

.ucc ... , no quantitativa informatioD has been fOUDd re1atiDg the VI to 

percent caDoPY cover. Further, the UI. of VI over natural landscapes hal 

received little, if aDY, attent.ioD. 

3) The theoretical framework for modeling the ob.erved vegetation 

cover from late11ite. exiltl, but hal been tested only to • limited 

degree. No .tud1e. review~d applied the modeling approach to semi-arid 

sYlte.l. Current av&1lable model.'need to be extended to model a mixed 

targ.t pixel. The ,ub,tantial amount of information aD plant caDopy aDd 

.oi1 reflectance. will facilitate te.ting of a theoretical model. 

Formulation of Percent Canopy CovI!r Algorithm. 

Two approache. for determining the percent canopy cover at a 

lub-pixel scale of re,olutioD have been formulated ba,ed aD the empirical 

10 
and theoretical relation.hlp. reviewed above. A f1r.t approach involve. 

developinl an a.pS~'cal or ... I-e.pirical relatlon.hlp batwaen the 

nor .. li.ad ve.etation index and the parcent canopy cover. A thaoretical 

approach Involve. adaptlnl the develop .. nt. of Otter.an (1978, 1981), 

Otter .. n et al. (1979, 1980), Davl. (1980), Unsar et al. (1981). Dozier 

(1981), and HcCloy (19~0) to a .ix*d target pixel. Both procedur.e. can be 

verified u.lnl ground truth obtained from exllting photograph •• 

"plrical Approach 

Since the canopy cover II functionally related to other plant and 

.oU par .. eter. (a.o.enberl et al., 1983), It 11 realonable to expect 800d 

corralation between the nor_llzed vesetation Ind.ex and percent canopy 

cover. The flr.t approach belnl con.ldered II 11891y to telt thll 

hypothelt. u.tnl HSS data and Bround truth obtalDI4 from exi'tins aerial 

photosraph •• 

Several variation. to the .1~le correlation Iche.e are envilioned. 

For ialtance, It II pOllible that the pre.ence of only a few pure or nearly 

pure pixel. (either completely bare lotl or completely g~een vegetation) 

.ay be luiflclent for providing bound. ~n the range of the numerical value 

of the VI which occur. w~~hln the lesment. Thele bounds would appear at 

the extre.e endl of • hiatogra. indicating the number of occurrence. verlu. 

VI a. shown in Figure 1. Once thele end pOl:l1tl are defined, the relative 

percentage of each cover type can be estimated by method. reviewed earlier. 

Th. validity of thi. approach relie. on the a.lumptlon that there 

exlstl a clear dlltlnction between loil and canopy reflectancel, and that 

the Inbomogeneltiel within the two leparate clalsel are Imaller than thOle 

between the sol1 and canopy. The allumption Is more apt to b .. vaUd if the 

11 
, ' 

"Pure" \" 

"Pure" 

Bare 

So11 

Pixels Green Vegetation 

\ 1---- -, 

t I , L... _ ___ I ...J 

r jliX~..1!.-f' 

I I t... _____ ~ 

Normalized Vegetation Ind~x 

Figure 1. Hypothetical Histogra~ of Number of Pixels versu~ Normalized Vegetation Index 

.. 
i 

~:"'~...::.' 

~i::Id~~I.i..~"',"~~"'IOOI't~r_I_'"",,' ,_,,,1.I!i!I .. IIIIMIlIll.0.llIil1JIlllIlliUll!!lblllil.·i1III11_IIII.IIIII11I111I.IIIIM.5. •• ___ [ 1I1.11..]]]U •• 1lI1P111111.l.lllllllidt •..•• n  lI.r. 

le,.ent analyzed il not "large", luch that the variability in different 

loi1 and plant typel il l.a11. 

Theoretical Approach 

Thi. procedure treatl the direct bea. fro. the target pixel al a 

linear co.bination of two or three individual .ub-pixe1 e1e.entl. Equation 

(3) can thu. be reformulated for the li.p1e two cover model al 

Lnr A • n t,. v + (1- n) ~ I (6) 

where n • the effective portion of a pixel covered with vegetation 

~ V 1m Radiance e.ittli'J4 froID veg.tation canopy In band A 

~. .. Radiance e.1tted fro. the soil in band A. 

The total nadir radS.ance will be the .UII of equliitiona (4), (5), and (6). 

The ana1y.i. will be limited to an optically thin atmosphere (clear 

sky) to reduce the influence of the scattering tar.. (Equations (4) and 

(5». Equations (4), (5), and (6) will be evaluated by allulling 

ref1ectancel for the different cover typel in each band, as well as the 

clear Iky Icattering and ablorption pargeterl T R' PR' T Itt PM al 

previously defined. Thele parameterl can be effectively estimated based on 

meteoro1agic condition. (Iqbal, 1983). An iterative scheme will be 

d6ve10ped to ms'nd.mize the difference between the computed and observed 

radiance., baled on luccelsive estimatel of n. 

Finally, lince there are four MSS bands, it il theoretically pOlsib1e 

to extend the above procedure to the cale of a pixel containing several 

cover typel. For eXPomp1e, the presence of t .. l'own herbage can significantly 

affect the overall canopy reflectance (Tucker, 1980). To account f.or this 

third cover type, the expreSSion for the direct beam from a pixel can be 

------""-

13 
IIOd if ied 8. 

wh.re, in addition to the previou.ly defined ter •• , 

'f • the effective portion of a pixel covered with brown 

vegetation 

~ b • Radian.:e e.itted fro. the brown vegetation in band A. 

The u.e of two band. will be required in this .ituation. The practical 

application of this ap~roach depend. on the abilitJ to define unique 

.pectral characteri.tic. for each of the three cover type.. Thi. condition 

i. !aportant not only for re.olving the data but al.o to .aintain linear 

independ.nce between the two direct be .. equations. 

Selection of Te.t Site •• 

Significant progres8 hal been achieved toward the .election of 

appropriate te.t lites for objectives 2 and 3 of the research (lee page 1). 

For the testing of the mixed-pixel algorithml, Objective 2, the two major . 

criteria are that 1) the region not be fully vegetated at ~ lub-pixel level 

of relolution and 2) the area must contain Landsat reconnaissance and a 

corresponding aerial photographic survey at approxtmately the same time. 

The aerial survey must be of sufficient detail that percent vegetation 

cover can be delineated. 

The criteria for lele,cUng a test site for testing Eagleson's 

hypothesi., Objective 3, are .ore .tringent. Test sites must be 

water-limi~ed, naturally vegetated, and at a near climate-climax state. 

Additionally, long term hydrologic and climatologic records must be 

available. It i. also desirable that climatologic data during the time of 

the surveys be avallablo. 

14 
I 

Th •• bov. con.tr.int. h.v. dir.ct.d the .ite-•• l.ction proce •• tow.rd 

the I .. i-.rid r.sion.' of .outhw, •• t Unit.d St.t... Nu •• roul .g.nci.1 

locat.d in tho.e r.gion. h.ve b •• n cont.ct.d including the N.tional P.rk 

S.rvice, the Pore.t S.rvic., the Soil Con.erv.tion S.rvic., the Bur •• u of 

L.nd Kan.g ••• nt, the U.S. G.ologic.l Survey, Arizon. St.t. P.rk., the 

Agricultur.l R •••• rch S.rvic. (ARS), and the Univ.rlity of Arizona. The 

inforaation provid.d by the varioul r.gion.l .nd .t.t. office. i. curr.ntly 

b.ing .xaain.d. H~.v.r, it app •• r. th.t the criteria for Objective 2 can 

b. e •• lly •• t. Por Obj.ctiv. 3, it i. lik,aly that the eventual lite be 

loc.ted in th. ARS .xp.rim.nt.l wat.rlhedl and/or the National P.rk.. The 

lit •• curr.ntly und.r con.ideration ar. the V.lnut Gulch Expert.ental 

Agricultur.l V.t.r.hed, ne.r Tomb.tone, Arizona, the Big Bend and Guadalupe 

Kountainl N.tional Perk., Texas, .nd the Carl.b.d Cavern. and Bandelier 

Nation.l Parks. New Kexico. Thea8 locatione are ne.~ O~ in the Sonoran O~ 

Chihuahuan De.ertl. 

The feasibility of obtaining concurrenl!; aerial photographic and 

Land.at d.ta has already been shown to be v~ry encouraging. The Belection 

process i8 being facilitated through the aerial photographic and Landsat 

search services conducted by the EROS Data Center, Sioux Falls, 

South Dakota. Additional source. of aerial photographic surveys which ha'lfe 

been contacted include the U.S. Department of Agriculture, Agricultural 

Stabilization and Conservation Service, Salt Lake City, and the U.S. Geological Survey, Plagltaff. As of this date, one search request has been, 

made through EROS for the Valnut Gulch Hydrologic Experimental Vatershed, 

Arbona. Hatching of the results for the aerial photographic and Landsat 

searches resulted in one period in October, 1978 in which both data were 
taken within two week.. Slnce thi. period is one in which canopy cover i. 

not lik~ly to chanle, both .urvey. can be u.e~ to te.t the .elected canopy 

cover allorith.. Sa~le photolraphl have been ordered fro. ASCS and EROS 

for the Walnut Gulch .ite. 

Additional .earche. for other areaa are currently underway. The .oat 

effective procedure i. flrlt to .eleet the leographic location, then to 

reque.t the aerlal photographic .earch. If an aerial lurvey of appropriate 

acale can be found for a period later than about 1972, it 1;J very likely 

that corre.pondl,ug .atelllte data will be avaUable tn light of the 

frequent coverage of the entire United State. by Land.at and NOAA 

latellite •• 
FUTURE RESEARCH 

Futur. r •••• rch will conc.ntr.t. on r.fining th. tw~ c.nopy cover 

forau1.tion. out1in.d above and th.n .pp1ying th •• to •• v.r.1 •• 1.cted 

ar.a~ in th. louthw •• t.rn Unit.d St.t... Once th. fin.1 site. h.v. be.n 

.el.cted. the .ntir ••• ria1 photogr.phic cov.r.ge will b. purch.sed .nd 

an.lyz.d for perc.nt c.nopy cover. The corr.sponding L.nds.t d.t. will 

th.n be analyzed in .ccord.nce with the .bove proposed technique. .t the 

GSFC. Any r.fin •• ents to the .bove procedur •• will then be •• de. 

Once •• uit.ble c.nopy cover procedure is est.b1ished. it will be 

app1i.d to the .ppropriat. te.t w.t.r.hed. Soil hydr.u1ic properties will 

be esti •• ted using E.g1e.on'. hypothe.is. Results will be verified using 

.ctu.1 streamflow d.t •• 

The fe.sibi1ity of u.ing Lands.t data to compute soil hydraulic 

propertie. will thus be established. A progt-.11 will then be designed ,to 

extend this procedure to other natural .ystellli. 
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MSS