the use of geographical information systems for cumulative environmental effects assessment

Cornput.. Envimn. and Ukmn Systwns. Vol. 17. pp. 393-407,1993 Prmted in the USA All rights resewed.

019s971593 8.00 + .@I Copyright 0 1993 Pergamon Press Ltd.

THE USE OF GEOGRAPHICAL INFORMATION SYSTEMS FOR CUMULATIVE ENVIRONMENTAL EFFECTS

ASSESSMENT

Sharon Parker

Environment and Planning Division, Auckland Regional Council

Chris Cocklin

Department of Geography, University of Auckland

ABST W ACT. In rty-opititm of the nt~l to th~lt~p trpprtmche~ to t~nvimnnu~tr ttd imptrct tmtmnletlt thtrt art- both profictive tintI which ttlkc ti witlt~r view of c~n~~irtifinic~,rttil clitin~r id its ctiuscs. tlrcri, iitls hf*c*tl iricretisiq irr trrt*st iti thcl mnct~pt of cuniirlcitir~e rnvirti~inu~nttil chtut~t~ tiritl its tis.st~ssnic’~it. W? tiirtlirrc~ tI tfrfinitimr t~rrtl cotrceptutil fromcwork for t/w trtdy.si.s of cun~rc~titivr r~ivirtirrnit,Iltn~ chtr~i~~~. T/W corrtrihrction of geo~rtrphictd inftrrmrriorr .sy.sttw~.s (GIS) to tlw cts.w.wnrrnt of cundt~tive rffecrs is ctm.sitkrd The potmtitrl is ttm ihstrtr ted by rcf~wwce to tm ~xtmpk of I/W rrsc of GIS in rc*.spcw of cunrultrtivt- effeca t~.s.w.s.smmt for N snudl arm of New Zrtdtr~rtl. The tmwtht prohltwu of using GIS in

this context tm itkn tifid turd di.scu.s.sctl.

INTRODUCTION

The application of geographical information systems (GIS) to cnvironmcntal managcmcnt and planning is increasing quite rapidly. This is II logical and appropriate dcvclopmcnt. given that monitoring and analysis in respect of cnvironmcntal change. rcsourcc distribution and con- sumption. and patterns of human activity, as it affects the cnvironmcnt, rcquirc explicit consid- cration of the spatial dimension.

The identification, monitoring and asscssmcnt of cumulative cnvironmcntal change (CEC) prcscnt specific opportunities for the application of GIS to cnvironmcntal managcmcnt. CEC. in its most gcncral terms. rcfcrs to the cffccts of multiple inputs to, or withdrawals from, natural systems. Explicit in the study of cumulative change is a recognition that the cxistcnt state of the cnvironmcnt is not simply the product of individual impacts occurring indcpcndcntly of each other. Environmental change is in fact the conscqucncc of many interacting factors, the combincd cffccts of which arc not always well understood.

Rcqucstc for reprints .should lx scnl IO Chris Conklin. DqxarUncnt of Gmgnphy. University of Aucklnnd. Privae Bag 92019. Auckland. NW Z&and.

393

394 S. Parker and C. Cock/in

It follows that cumulative effects assessment (CEA) is concemcd with identifying and evalu- ating the impacts of multiple inputs (or withdrawals) upon the environment. CEA assumes a broader frame of reference than traditional environmental impact assessment (EIA). For exam-

ple, the former is distinguished by a concern for the combined effects of several developments (perhaps unrelated), unlike conventions EIA, in which projects arc assessed individually and independently of other developments. in this respect, CEA describes more accurately how environmental change is brought about in many circumstances.

The main objective of this paper is to illustrate by example how GIS cilll contribute to CEA. This is achieved by describing our recent experience with the use of a GIS to document aspects of CEC in a small area of New Zealand. In this paper. WC consider also some of the attendant problems that arise from using spatial information technology in this context. To establish a conceptual framework for the paper, the following section presents, at greater length. a charac- terisation of CEC and its assessment.

CUMULATIVE ENVIRONMENTAL CHANGE AND CUMULATIVE EFFECTS ASSESSMENT

Over the last decade. attention has been given to dcvcloping useful definitions of CEC (SW.

for example, CEARC & U.S. NRC, 1986; Cobourn, I9S9; Cockfin, Parker. clr Hay, 1992;

Pctcrson et al.. 19X7; Sonntag ct al., 1987). It is not our intention to rcvicw thcsc contribu- tions at Icngth here, hut rather to prcscnt an ahhrcviatcd and focused intcrprctation of CEC and its analysis.

Figure I is prcscntcd tcl help clarify our meaning and intc~r~t~lti(~n of CEC. As WC suggest in the figure, it is useful to rccognisc three diI3l~nsi~~ns: sources of change, pathways of accumulation, and impact accumulation.

r -_-

Sources of Chsngo -Ii------ Pathway, ol Accrrmut~l~on -‘-‘-‘-jf-imGzGzzz- 1

Environmental Foodbacks

Exisbnt Stato of Thresholds 01

Socio-economic Feedbacks

1 )I Evaluation 1 Physic~WEiolo~icai Scicncos

I ProJCZ _ __ _ _.__L._ L Rexw@ 1 .s b&NYIgt?mx7t (Insfifulion?l and Poltcy Science )

FIGURE 1. The Concept of Cumulative Environmental Change.

G/S and Cumulative Environmental Effects Assessment 395

Sources of Change

In the simplest classification. sources of change can be defined as either single or multiple. A single activity. such as an industrial facility. will inevitably have several effects upon the environment. some of which may be interrelated. We can refer to the cumulative changes brought about by this single activity. From a somewhat different perspective. several operating units of a single type of activity, such as pastoral farming. can have individually minor, but col- lectively significant environmental effects. This has been referred to elsewhere as “space crowding” (CEARC. 1988, p. 3).

More typically, cumulative change is associated with multiple sources of activity. Therein, the concern is focused on the combined impacts of two or more sources of disturbance (e.g.. of a power station and an industrial facility).

Pathways of Accumulation

CEC can bc distinguished also with rcfcrcncc to the ways in which inputs to the cnvironmcnt combine to bring about disturbance. Two main pathways arc rccogniscd; additive/crowding

and intcractivc/compounding (e.g.. synergistic). An additive/crowding pathway is characteriscd by the fact that inputs or withdrawals comhinc in a linear fashion, with each unit of activity creating much the same lcvcl of disturbance. A cumulative cffcct results from the accumulation in spatial and temporal terms (crowding). Intcractivclcompounding rcfcrs to more complex pathways of change. such as synergistic cffccts or when pollutants accumulate through the food chain (hioaccumulation).

Impact Accumulation

In this rcspcct, a distinction can bc drawn bctwccn an “accumulation of impacts” and an “accumulative impact.” The former dcscribcs a situation in which thcrc is a divcrsc range of impacts, perhaps unrclatcd. which contribute to an overall degradation of the cnvironmcnt (c.g., within a region. industry giving rise to air pollution, intcnsivc farming leading to pollution of waterways. and the accumulation of waste products from various human activities).

An accumulative impact results when two or more, perhaps unrclatcd, activities contribute to a single form of cnvironmcntal disturbance. The burning of fossil fuels rclcascs carbon dioxide, and agricultural activities give rise to outputs of mcthanc. both contributing to climate change.

Thcsc dimensions of cumulative change and the distinctions that have been drawn give rise to a simple classification that WC have utiliscd to assist in structuring CEAs. Four types of inquiry could contribute to a systematic CEA:

I. the assessment of the cffccts of a single activity upon a single cnvironmcntal attribute. 2. an assessment of the effects of a single activity upon multiple cnvironmcntal attributes, 3. an assessment of the effects of multiple activities upon a single environmental attribute. 4. the asscssmcnt of the effects of multiple activities upon multiple cnvironmcntal attributes.

Within each of thcsc catcgorics. pathways of chungc may bc additive or compound. WC pro- vidc, subscqucntly, cxamplcs of three of thcsc types of analysis.

In outlining our framework for CEA, one further issue is of fundamental importance. EIA has traditionally been project-oricntcd. Upon submission of a proposal for dcvclopmcnt. the conscqucnt impacts upon the cnvironmcnt arc anticipated and cvaluatcd. This approach to impact asscssmcnt is reactive in the scnsc that it seeks to control impacts (see Figure I) and offers limited scope for identifying and considering cumulalivc impacts.

396 S. Parker and C. Cocktin

By contrast, we propose an approach to environmental management and impact assessment that is more proactive and which is designed explicitly to rccognise cumulative effects. According to this approach, the state of the environment and changes to it are examined from a regional perspective. Cumulative effects upon the environment need to be documented, and

any future proposals for development must be evaluated from a regional perspective. A more proactive and broad-based approach to EIA had been advocated by some since soon after the introduction of the U.S. National Environmental Policy Act in 1970 (see, for example,

Anderson, 1973; O’Riordan. 1976). Since then, others have recognised the advantages of regional approaches (e.g., Cooper & Zedler, 1980). but to date, the institutional arrangements

for EIA in most countries have continued to focus on project-level assessments. Our disposi- tion towards regional-level CEA establishes a well defined opportunity for GIS to assist with

environmental evaluation and management.

GEOGRAPHIC INFORMATION SYSTEMS AND CUMULATIVE EFFECTS ASSESSMENT

To be effective. CEA will need to draw upon a diverse range of analytical proccdurcs and methods. These will range from those based in the traditional biophysical scicnccs through to those of the institutional and social scicnccs.

Within a regionally-hascd assessment of CEC. GIS has an important role to play, given the facilities for handling large quantities of spatially rcfcrcnccd data. In particular, GIS offers the capability to identify, with accuracy, spatial overlaps and proximities, to portray and assess the spatial dispersion of cffccts and, within scenario analysis. as a basis for rcprcscnting the spatial distribution of anticipated changes. Thcrc exist also the opportunities to display changes in the sta~c of the cnvironmcnt through time.

The potential for GIS to contrihutc to CBA has hccn idcntilicd by others as well. Johnston, Dctcnhcck. Bondc. and Nicmi (198X. p. 1609). for cxamplc, noted: “Geographic Information Systems provide a practical means of conducting Cl (cumulative impact) asscssmcnts bccausc of their ability to compile, process and cvaluatc data collcctcd over a long time period and for a Iargc geographic arca.” In rcvicwing some spccilic applications (eg.. cumulative impacts on grizzly bear communities), P. Lane and Associates (19X8) noted the particular advantages of GIS in terms of rcprcscnting the spatial dimensions of change and the case of communicating findings. More generally, Moffatt (1990) asscsscd the potential of GIS to contribute to cnviron- mental managcmcnt. concluding that it could assist in formulating cnvironmcntal managcmcnt stratcgics, contribute to the avoidance of resource-use prohlcms. and help to identify arcas of special importance (e.g., areas with high capability for food production). GIS, he argues. should be able to cnhancc our understanding of, and thcrcforc improve our managcmcnt of,

environmental problems. The database-handling capabilities and the special advantages in terms of representing and

analysing the spatial characteristics of cnvironmcntal change clearly earmark GIS as a tool with a particular contribution to make in terms of CEA. cspccially when the analysis is rcgion- ally based. Some spccitic functions in this context are:

1. prcscntation and updating of surveys of both the natural and human environments (i.e. state of the environment reporting). thus providing a context for considering proposed or likely dcvclopmcnts. from a regional perspcctivc;

2. analysis of the spatial relationships between natural and human aspects of the environment

(c.g., proximity, crowding); 3. analysis and prcscntation of spatial changes over time (e.g.. population distribution/density

changes, land-use changes. loss of native forest);

GIS and Cumulative Environmental Effects Assessment 397

4. the presentation and analysis of scenarios for the future - “what if’ analyses (e.g.. If

urban areas expanded in area by 10 percent. how much farmland would be lost? In what areas and of what quality? Where should this be discouraged?).

The applied analysis on which we report subsequently in this paper is characteristic primari- ly of the second type of application listed above. In Figure 2. we provide a representation of the general procedure that might be adopted in the context of such an analysis. Following from our general classification of CEA presented earlier, the diagram identifies the pairing of activities and valued environmental components (i.e., impact categories), in this case focusing on multiple activities and multiple impacts. The example refers specifically to the possible effects of various human activities upon components of the biological environment. In the simplest analysis, the GIS might be used simply to identify spatial overlaps and proximities. More sophisti-

cated analyses could draw upon causal models in an attempt to predict with greater refinement the specific changes in the environmental attributes relative to types and levels of human activity. The examples on which WC report identify simply spatial proximities, as opposed to pro- ceeding with the task of causal modclling.

DATA SOURCES FOR AN APPLIED CUMULATIVE EFFECTS ASSESSMENT

To illustrate the potential contribution diffcrcnt mcthodologics could make to the asscssmcnt of cumulative cnvironmcntal cffccts. a study arca with the following characteristics was chosen:

l boundaries of the arca wcrc dcfincd on a basis that is meaningful in cnvironmcntal Icrms

(i.c.. using ecological crilcria);

l an arca that exhibits important social and economic values; l an arca of sufficient size to bc consistent with an approach to CEA that cmphasiscs a

regional perspective; l an arca that exhibits important cnvironmcntal values.

VALUED ENVIRONMENTAL

COMPONENTS

ANALYSIS: -overlays REPRESENTATION:

PROCESS/ -buffcrs -maps CAUSAL - -zoom - -graphics MODELS -nearest -re 01%

neighbour g -fa les

HUMAN ACTIVITIES

FIGURE 2. Geographical Information Systems and Cumulative Environmental Change.


Study Area

The area chosen for the applied study is known as the Meremcre Ecological District, and is of about 1,000 km? in extent. Ecological districts are subareas of New Zealand which have been dclined according to physical and ecological criteria. New Zealand has been divided into 268 ecological districts. One of the dominant physical features of the Meremere Ecological District. an interior basin. is the Waikato River, which effectively bisects the region. To the northwest. the alluvial flats are bordered by hill country. In the east and southwest, the flats

incorporate extensive wetland arcas (approximately 19,500 hectares [ha], or 18% of the total area), including the internationally significant Whangamarino Swamp that lies to the northeast. Approximately a dozen shallow lakes arc scattcrcd through the region, but are concentrated in the south.

Large deposits of high quality coal undcrlic surface fluvial scdimcnts. and the region has a history of coal mining and associated thermal clcctricity generation. The fertile soils have been used for intensive and extcnsivc sheep and dairy farming, for which vast areas of the original bush cover have been clcarcd. A major state highway and the North Island main trunk railway

run north-south through the region.

Data Sources

The asscssmcnt of CEC imposts quite significant demands in terms of data sets. In particular, the comprchcnsivc, regionally-hascd approach to CEA that WC advocate rcquircs a wide variety of data relating to both the natural nncl human cnvironmcnts. This variety is illustrated in Tahlc I, which indicates major data sets that may hc rcquircd to implcmcnt a GIS in support of a CEA. One of the major advantages of GIS is that it is ahlc to integrate spatially rcfcrcnccd data sets from a variety of sources. scales, and times. Ilowcvcr, thcrc arc the attendant prohlcms of reconciling the scale, accuracy, and dates of capture, since thcsc ultimately have ;I dctcrmining cffcct on the accuracy of the analysis.

The spatial detail in the data must hc appropriate to the scale of the analysis. A mcasurcmcnt taken only at one place (or cvcn two) will not yield information on geographic patterns.

Convcrscly. seldom is high spatial intensity of data a problem, given the high volume storage capabilities of modern computer equipment and the ability to aggrcgatc dctailcd information

into more gcncral unils. Morcovcr. data should hc availahlc for the whole of the study arca, which in the cast of a

regional approach, may prccludc information collcc~I as part of individual. small-scale projects. Howcvcr. the sum of data from a scrics of projects may prove valuable for CEA. albeit time-consuming to collect. It is seldom appropriate. howcvcr, to directly compare mcasurc- mcnts of the same paramctcr by diffcrcnt groups using diffcrcnt tcchniqucs and assumptions. In the context of the reported study, this posed particular prohlcms in terms of information on water quality, for cxamplc.

The desirability of measuring change through time means that time scrics data sets arc of great value for CEA. The significance of the temporal clcmcnt in CEC is that individually insignificant actions, over time. may have a cumulatively significant cffcct on the cnvironmcnt. Time scrics data can rcvcal major trends and changes (over and ahovc natural variability). and this may allow action to bc tnkcn to uvcrt further change hcforc irrcvcrsiblc damage occurs. in the applied study, WC found data sets providing the historical pcrspcctivc difficult

to ohtain. Data for the cast study wcrc availahlc in digital form. manuscript form, and as aerial pho-

tographs. The two major sources in digital form wcrc the New Zealand Land Rcsourcc

G/S and Cumulafive Environmental Effects Assessment 399

TABLE 1. Data Layers for a Regional Cumulative Effects Assessment

Natural environment Valued ecosystem components

Atmospheric - air quality Aquatic -water quality Fauna1 - species distribution and abundance Floral - species distribution and abundance Terrestrial Ecosystems

Physical environmental characteristics Topographic contours

Geology Soils Hydrology Vegetation Climate

Rainfall (annual, seasonal) Temperature (annual, seasonal) Wind speed and direction

Human environment Social/political characteristics

Cultural/historic sites Land ownership Maori tribal boundaries Administrative boundaries Census boundaries and associated census data

Human activities Built-up areas Agriculture Transportation Industrial activity (including power generation) Mining activities Land use

Inventory (NZLRI). and sclcctcd Census data from the New Zealand Dcpartmcnt of’ Statistics. The NZLRI was the primary sourcc of information on the physical geography of the region. It came in the form of land inventory unit boundaries and associated lcgcnd information. For each of the NZLRI land units, the latter included rock type, soil unit. slope, erosion. vegetation, and agricultural land-use capability asscssmcnt. The units wcrc “clipped” out of a national

database to conform with the boundary of the study arca and supplied in digital form compati- blc with the GIS WC wcrc using (ARC/INFO; Environmental Systems Rcscarch Institute [ESRI], Rcdalnds, CA).

Data from the New Zculand Dcpartmcnt of Statistics wcrc supplied as mcshblnck boundaries (the smallcst unit of data aggrcgution) and identification numbcrs. along with demographic, cmploymcnt. and income statistics. Some adjustments wcrc ncccssary to convcrt the Dada to a

form compatible with ARC/INFO.

The primary manuscript data source was the NZMS 260 map scrics, issued by the New Zealand Dcpartmcnt of’ Survey and Land Information (DOSLI). The NZMS 260 is a topographic map scrics. puhlishcd at a scale of 150.000. It includes transport networks. built- up arcas. larger industries. hydrologic fcaturcs. and forcsl cover. In addition to the NZMS 260 scrics. scientific studies and various reports wcrc used as nccdcd to provide supplc- mcntary information.


CUMULATIVE EFFECTS ASSESSMENT: MEREMERE ECOLOGICAL DISTRICT

We present below, three examples of the use of GIS in rcspcct of documenting characteris-

tics of cumulative environmental effects within the study area. These selected examples arc a

subset of a more wide-ranging analysis, the primary objective of which was to dcmonstratc

that GIS can make an important contribution towards environmental planning and managc-

ment at a regional scale. The examples, of necessity. are rclativcly simple, but scrvc to illus-

trate the powerful data-handling attributes, the capability to overlay information layers. to

define buffer zones, and calculate the arcas of irregular geometric shapes. Moreover, the

examples provide first-order insights into some of the characteristics of CEC within the

Mcrcmerc district. WC rcfcr here to only three of the four types of cumulative asscssmcnt

that we have dclincd above. since this subset provides a sufficiently rcprcsentative cxamplc

of our USC of the GIS. Rcadcrs should not find it difficult to extrapolate to the fourth type of

analysis. or indeed to quite diffcrcnt cxamplcs and contexts.

Single Activity - Single Attribute

The first cxamplc illustrates the cumulative impact of a single activity in terms of a single

cnvironmcntal attribute or valued cnvironmcntal component (VEC). Hcrc, the concern is with

the impact of agriculture upon wetlands. Marc specifically. the oh.jcctivc was to identify the

arca of wetland that has hccn displaced by high producing pasture. The analysis relics almost

cxclusivcly on the NZLRI data set. From this, arcas of land in paslurc can bc idcnlilicd. WC

adop~cd Ogle and Chcync’s (IYXI) list of land-USC capahilitics that they assume IO corrcla~c

with the prcscncc of wetlands as a basis li)r dclining their historic covcragc. A combination ol

Iand-use capability and primary vcgctution then provided an cstimatc of the arca previously in

wetlands and now occupied by high producing pasture. The rcsuhs arc prcscntcd as Figure 3.

The actual arca of wetland displaced, cstimatcd via the GIS. amounts to 6,605 ha. or about

25% of the original covcrugc.

This provides a vivid cxamplc of an impact that is spatially accumulative, or what, under

one typology of cumulative cffccts. is rcl’crrcd to as space crowding (CEARC, I9XX). The

impact of individual economic units (farms) may hc relatively minor, but wetland displacc-

mcnt throughout the region by pastoral activities assumes some signilicancc - the tymnny

of small decisions in Odum’s (1982) terms. The impact is accumulative in a temporal sense

as well, although the time dimension is rcprcscntcd hcrc in its crudest form (“then” and

“now”).

Scvcral types of follow-up analysis might bc rclcvant. Through the USC of air photos and

other information, it may bc possible to clarify the pattern of change through time. Also. the

VEC (wetland area) is a rclativcly coarse criterion for evaluation, and it may bc informative to

rcfinc the asscssmcnt by cstimuting impact in terms of suhcritcria (c.g.. flora and fauna). It

might also bc important to obtain a more prccisc charactcrisation of the activity (i.c.. what

types of land-use have displaced wetlands). Beyond thcsc. a subscyucnt step in our CEA would

bc to identify other activities that have afrcctcd the status of this VEC.

Multiple Activities - Single Attribute

This cxcrcisc is a logical cxtcnsion to the first. In this cast. the analysis is cxtcndcd to

include the cffccts of all land uses on wetlands (Figure 4). Other land uses that now occupy

arcas that wcrc previously wetlands arc exotic forest, low-producing grassland. and rcgcncrat-

ing native forest (manuka [Lep~~>.~p~‘~n~~rn sco\~rriunt] and kanuka [Kunzea ericoides]).


0

KIlomstrcJ

@j Extent of wetlands, 1977 (19,567 Ha)

S Extent of past wetlands lost to high producing pasture (6,685 Ha)

FIGURE 3. The Loss of Wetland Areas to High-Producing Pasture.

Relative to agriculture, thcsc uses have displaced ;1 small arca of former wetland (comhincd arca of 1, I73 ha). Thus, white thcrc has been a cumulative cffcct in tams of activities affecting this VEC, pastoral agriculture has had the dominant impact.

Multiple Activities - Mu/tip/e Attributes

To many. this is the archctypal cumulative cffccts asscssmcnt since it offers the summary or holistic view. to which the previous cxcrciscs might contribute. This part of the applied CEA helps to identify a potential for impact by scvcral activities upon two vlrlucd components of the natural environment. In this third cxrtmplc, WC move to the northern rcachcs of the Wh~n~m~in(~ Swamp, the rcm~inin~ major wetland within the region. The activities consid-

crcd hcrc arc transportation. thermal clcctricity gcncration, rccrcation, and coal mining. In the carlicr cxamplcs. the VEC was dcfincd as wetland. This is now disaggrcgntcd into two more specific evaluation criteria: North Island fcrnbird (Bowdleria pncruro vealeoe) habitat and

remnant kahikatca (Ducr~curpus ~uc~~i~~i~~s) forest. In Figure 5. the spatial coincidcncc of human activities and certain natural values is identi-

ficd. Around the human activities, a buffer zone has hccn drawn at various distances. Although WC have chosen the distances to the pcrimctcr of the buffer arbitrarily, it would bc dcsirahlc to identify a more rational basis for demarcating the possible outward distribution of effects.

402 S. Parker and C. Cocklin

Remaining Wetlands (19,567 Ha)

High Producing Pasture (6,665 Ha)

Exotic Forest (839 Ha)

Lowproducing or Native Grassland (26

Manukn, Kanuka (73 Ha)

---____-__

FIGURE 4. The Loss of Wetland Areas to Other Land Uses.

This provides ;m cxamplc of possihlc h;rhitat kqpcnt;~tion, sincc some arcas of fcmhircl habitat

arc complctcly surrounded by transport rou~cs. Within our hull’crs. 4% ha ol’ the habitat arc includ-

cd. As well, mining, rccrcation ;lnd transportation XC all in proximity to the small arcas of remaining

kahikatcu forest (8.5 ha in huffcrs). Asscssmcnts ;LS to whcthcr or not the bird habitat or remnant for-

cst arc rrctually impaclcd by thcsc dvitics must rely on ;I closer examination of the circumstances.

fl Kalrikdlen stands

Key fernbird habitat

jljll Area sublecl lo most recrcalio2al use

- Ouffer around human act

Transporlalion roules

.ivilies

FIGURE 5. Proximity of Human Activities to Native Vegetation and Bird Habitats.


The example illustrates two additional analytical capabilities of the GIS that are useful in the

context of CEA. The first is the capability to adjust the scale of analysis, in this case allowing us

to focus on a specific subarea of the region. The second is the capability to define buffer zones.

ISSUES AND PROBLEMS

This section describes the particular problems and issues which wcrc encountered in

attempting to USC GIS in the context of CEA. with the above-mentioned data sources. The dis-

cussion is presented in two sections: data problems and methodological problems.

Data Problems

Information Coordination Environmental information has been collcctcd by a variety of agencies and individuals in the

course of their work. In New Zealand. howcvcr, thcrc is no one place or agency whcrc rcport-

ing of such information is coordinated. It would bc dcsirablc for such a scrvicc to exist, so that

maximum bcncfit could bc gained from rclatcd information collcctcd by diffcrcnt groups. For

cxamplc, a stream biologist may collect water quality data in order to charactcrisc the aquatic

habitat of the study spccics. A scientific institution may huvc a monitoring site in the same

arca. Each group may have information valuable to the other. and to cxtcrnal groups with an

intcrcst in water quality in the arca, yet they often do not maintain links nor coordinate their

activities for mutual bcnclit.

The groups may feel that hccausc they have diffcrcnt ohjcctivcs and arc operating 011 diffcr-

cnt schcduics, they cannot rest their work on the same data sets. Altcrnativcly, the information

may bc considcrcd scnsitivc by an owner (c.g., a private company) who is not prcparcd to

rclcasc it for public scrutiny.

The cxistcncc of a scrvicc for information coordination would. perhaps. cncouragc coopcru-

tion bctwccn information gathcrcrs and users. This would rcducc costs and unncccssary pmlif-

cration of’ data, as well as clarifying the many gaps in information that currently exist. Thcrc is

some feeling in New Zealand that regional govcrnmcnt is in the idcul position to do this. Under

recently enacted Icgislation - the Rcsourcc Managcmcnt Act of 1991 (New Zealand

Govcrnmcnt. I99 I ) - regional govcmmcnt in New Zcalund has. in fact, been given the man-

date to monitor and report on the cnvironmcnt. Regional information invcntorics could then

link into a national system. providing that common standards and data collection proccdurcs

arc obscrvcd.

Data Collection and Recording Standards Following from the above. thcrc is a clear need to climinatc unncccssary rcpctition in cnvi-

ronmcntal data collection and to dcvclop appropriate data collection and recording standards - in rcspcct of both methodology and reporting crrur. Our cast study cncountercd inconsistcn-

ties in water paramctcr reporting, such as variance rccordcd as “lowest value” and “highest

value” in some casts and mean and standard deviation in others. or differing sample sizes. rcn-

dcring meaningful comparison of the diffcrcnt data sets impossible.

Some sources, on the other hand, provided supporting material describing the methodology

and philosophy of data colicction, so that the dcgrcc of uncertainty in the data was clear, and

the dcgrcc of comparability of data sets could bc asccrtaincd. Thcsc sources wcrc typically

those rccordcd nationwide and carried out by cc~ally coordinated agcncics. The most notable

data in this category arc the NZLRI (Dcpartmcnt of Scientific and Industrial Rcscarch). Census

information (Dcpartmcnt of Statistics) and NZMS maps (Dcpartmcnt of Survey and Land

Information).


Although data reported at the national level have major advantages, the degree of detail in some cases may not be adequate for the user’s application. For example. the average size of NZLRI land units in the study area is approximately 2 km*. The level of detail attainable is thus limited, but the data were acceptable for analysis on a regional scale. and of considcrablc value given their scope and ease of incorporation into the GIS.

Currency of Information The degree to which information available to the study was of consistent and recent origin

was extremely variable. Data were used which had been collected in the early 1970s. and others as recent as 1990. as Table 2 shows.

Since the case study was for illustrative purposes. the currency of the data on which it rcst- ed was not considered vital. In practice, such variability and age of data would bc a real concern. Unfortunately. recent data arc not always readily availahlc - a consequcncc, in many cases, of changing research priorities, and falling lcvcls of funding for research and informu- tion gathering.

One may expect govcrnmcnt agcncics to phtcc high priority on gathering and regularly updating environmental information. This is ohscrvcd to perhaps the most satisfactory dcgrcc in New Zealand by the Dcpartmcnt of Statistics, in rcspcct of information pertaining to the social and economic cnvironmcnt. One could argue that it is the role of such an agency to keep vital national statistics on the state of the cnvironmcnt as well, which is poorly understood. yet

knowlcdgc of which is csscntial for dcvcloping and implcmcnting policy for sustainahlc cnvi-

ronnicntal managcmcnt.

Format of Original Data Section 3 indicated that data used for the cast study W;IS in three principal forms: digital,

manuscript. and acriul photograph. The grcatcst cxc of data integration WIIIC from data sup-

plied in digital form compatihlc with the GIS softwurc being used for the project (ARC/INFO).

The only information Irvailablc in this format was the NZLRI.

Dcpartmcnt of Statistics information from the 19x6 Census of populution was obtained in

digital form from CD ROM tahlcs in ;L package called SUI’ERMAP (New Zealand Dcpartmcnt of Statistics, Wellington. NZ). Mcshhlock houndarics digitiscd by the Dcpnrtmcnt of Survey

and Land Information wcrc supplied with mcshblock numhcrs. The CD ROM data wcrc

uttachcd to the mcshhlocks using the common item of meshblock numhcr.

Manuscript informtltion was digitiscd hy hand as nccdcd - a lahour-intensive hut ncccssxy

task. Prohlcms wcrc cncountcrcd with source maps not having a scale, nor reporting which

projection the map was based on, nor being available on stable h~sc material. The errors in

digitising resulting from this wcrc compcnsatcd for by rubbcrshccting whcrc possible, and

attempting to fit lincwork from less accurate bases onto bases known to bc of higher accuracy.

In the area of cnvironmcntal asscssmcnt. high accuracy is gcncrally not so important as in

other disciplines. such as land valuation. This is cspccially true given the knowlcdgc that lines

TABLE 2. Recency of Selected Data Used in Meremere Study

--_-_- ---.

NZLRI Waler quality NZMS 260 maps Wildlife habitat Census data Air quality

early-mid 1970s 1973-l 966 (discontinuous) early 1980s 1983 1966 1990 ~~ ___-

GIS and Cumulative Environmental Effects Assessment 405

drawn on the basis of ecological values arc, at best, approximations or abstractions of the indis-

tinct boundaries that exist in reality. The potential for satellite imagery to contribute materially to CEA on a regional level is very

high. for several reasons:

1. It is available in digital form, for direct input to a GIS. 2. It is current (typical orbiting frequencies of a few weeks). 3. It is collected repeatedly over time, in a routine fashion, providing the temporal

dimension, which is important in monitoring environmental change. 4. The degree of resolution (SPOT monochromatic pixels at 10 m x 10 m, and multispectral

at 20 m x 20 m) is high enough for regional environmental patterns to show well. 5. Coverage is comprehensive and uniform over the entire area of interest.

The problems with using satcllitc imagery arc that all images require preprocessing to render them useful in land-rcsourcc studies. and that the advantages it has over aerial photography arc significant only at mapping scales of 1:50,000 or smaller. Aerial photographs can be digitiscd, but problems of strong bidirectional rcflcctance and lens fall-off rcndcr automated classification of the imagery difficult (Trotter. 1991). Marc commonly, aerial photographs arc manually intcrprctcd bcforc being digitiscd manually.

Whatcvcr information is input to the GIS. a careful record must be kept of the .scalc of the original maps, and the lcvcl of accumcy of the d&t. This is bccau~. in digital form, geographical information is “scalclcss.” although it is only as rcliahic as the original material from which it was taken.

cost The current “user pays” philosophy of the New Zealand govcrnmcnt has pcrmcatcd all facets

of goods and scrvicc dclivcry, and information supply has certainly not been immune. All intcrcsts, bc they public or private, arc now rcquircd to pay for information supplied. In some instances, the cost of rctricving the data is charged. while in others, churgcs rctlcct the true cost

of collecting the information. The justifiability of full-cost charging, particularly in the cast of govcrnmcnt dcpartmcnts. is

qucstioncd hcrc. Considcrablc variability in charging prncticcs has also been noted. While it is acccptcd that data collection costs must bc met somehow. and that those who bcncfit from this should pay most, thcrc is, noncthclcss. a moral obligation on the part of information suppliers to cnsurc that those who rcquirc information have access to it at rcasonublc and cquitablc cost.

Methodological Problems

Causal Links GIS cannot by itself account for proccsscs of environmental change. It can intcgratc infor-

mation from a variety of sources, analyst spatial rclntionships (e.g., rccognizc that a and b UC spatially coincident, dctcrminc how much of z occurs within 20 m of y). and identify arcas whcrc dcfincd phcnomcna arc coincident (e.g.. all arcas with cxtrcmc soil erosion problems

that arc under pasture). Howcvcr. GIS cannot rcvcal why or how such phcnomcna come about. For cxamplc. why do high lcvcls of lead occur in soils near highways? How wide dots a buffer around wildlife habitat need to bc to protect the arca from noise cffccts? Such questions can bc answcrcd only by rcfcrcncc to scientific study. to cxpcrt judgcmcnt, and by the complcmcntary USC of other asscssmcnt methods (such as matrices. models. statistical analysts).

The spatial analysts WC pcrformcd assumed additive proccsscs of accumulation. Although not impossible to incorporate into GIS, more complex proccsscs of accumulation would involve additional assumptions and methods.

406 S. Parker and C. Cocklin

Data tntegratjo~ One of the advantages of GIS is seen to bc its ability to integrate data from many diffcrcnt

sources, scales, and times. However. this very capability is also a potential problem, since the

question arises as to how meaningful the results of this integration are. Is it appropriate to com-

bine 1983 info~ation with 1990 info~a~ion and draw conclusions as to spatial relationships

that may not have occurred at the same place and time? There is a need to formally incorporate

error estimates into spatial analyses done within GIS.

SUMMARY AND CONCLUSIONS

To achieve grcatcr effectiveness and better outcomes. environmental assessment and man-

agement must move forward from its traditional narrow focus. The notion of cumulative cnvi-

ronmcntal effects assessment cstablishcs a possible framework for a more proactive, intcgratcd.

and br~~ad-based approach to cnvir(~nmcntal planning. This will rcquirc some quite fund~m~n- tai changes to the institutional settings in which cnvironmcntal managcmcnt takes place. Thcrc

is also a requircmcnt to bring new pcrspcctivcs and methods of analysis to cnvironmcntal

asscssmcnt and managcmcnt. In the context of regionally-hascd CEA, thcrc is obvious potcn-

lial for GIS to contribute signiftcantly.

Hcrc, the data handling and some analytical ~a~~~biliti~s of GIS systems of rcfcvancc to CEA

have hccn dcmonstratcd. The cxcrcisc has sorvcd to help confirm the mlc that spatial informa-

tion technology can play in rcspcct of regional cnvironmcntal analysis.

The applicakn of GIS to the analysis of cumulative cffccts will not hc without its diffkul-

tics, and those that have hccn noted hcrc arc not atypical of GIS ~lr~pli~;itions. In the WC of

GIS for CEA, these problems arc incvitahly acccrttuatcd, since data arc gathcrod from

divcrsc sources. for a large geographic arca, and (ideally) over cxtcndcd time periods. The

integration of such data into a meaningful analysis is a difficult task, although cased hy an

understanding of the natural proccsscs occurring. and the use of cxpcrt judgment and com-

pl~in~nt~ry methods.

In spite of the diflicultics, the potential for GIS in this context is considerable. Thcrc will bc

a need lo USC methods which can complcmcnt CIS for the anrrlysis of CEC - methods such as

process mod&. network analysis, matrices. and the use ofcxpcrt judgment. In the meantime, it

will take the conceptual and institutional shifts towards CEA on a widcsprcad basis to more

distinctly establish the dtmand for this technology in the context of regional cnviron~ncntal

munagcmcnt and analysis.

REFERENCES


P. Lane & Associates (1988). Reference guiuk 10 cumulofirr eficrs assessment in cnnutiu (Vol. I). L~npubkshed rep7

submitted to Canadian Environmental Assessment Research Ccuncil. Moffatt. 1. (1990). llx potentialities and problems associated with applying infotmation technology to environmental

management. loumd of Envimnmenfol Munqemenf, 20.209-220. New Z.ealand Government (1991). The Resource Manugemenf Act. Wellington. NZ: Author. Odum. W. (1982). Environmental degdation and the tyranny of small decisions. Biasaence. 32.72X-729. Ogle, C.. & Cbeyne. J. (1981). The wi&fIije and wildlife values uf rhe Whangamur~no wetlands. Wellington. NZ:

Department of Internal Affairs. O’Riordan, T. (1976). Environmenk.dism. London: Pion. Peterson, E. B.. Ghan. Y.. Peterson, N. M.. Constable, G. A., Caton. R. B.. Davis. C. S.. Wallace. R.. & Yarmnton.

G. A. (1987). Cumulutive eflecrs assessment in Canadu: An agenda fur action and research. Hull. Quebec: Canadian Envimnmentd Assessment Research Council.

Sonntag. N. C.. Eve&t. R. R.. Rattie. L. P., Colnett. D.. Wolf. C. f?. Truett. 1. C.. Dorcey. A.. & Helling. C. S. (1987). Cumulative effecrs assessment: A context for further research and developmrnr. IIull. Quebec: Canndian Environmental As.wsFment Research Council.

Trotter, C. M. (199 I ). Remotely-wwd dam a an information source TM geographical information systems in nnturnl resource management: A review. Internurionul Journul of Grogrclphicul Inf~onndon Swems. 5. 225-239.

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