Spatial information for Integrated Coastal Zone Management ... · of a spatial data intensive ‘Coastal Action Plan’ approach be considered in the future, to allow already established

SPATIAL INFORMATION FOR INTEGRATEDCOASTAL ZONE MANAGEMENT (ICZM)AN EXAMPLE FROM THE ARTIFICIAL ENTRANCE CHANNEL OF THEGIPPSLAND LAKES, AUSTRALIAPeter Wheeler, Monash University

Peter Wheeler is a Ph.D. student at the Centre for Geographic Information Systems, in theSchool of Geography and Environmental Science, Monash University. His current researchproject is related to GIS diffusion and deployment for Integrated Coastal Zone Managementin Victoria, Australia.

Since 1889, an artificial entrance channel, cut through the swash aligned Holocene sandy outer barriersystem known as the Ninety Mile Beach, has provided shipping access between the Gippsland Lakes andBass Strait. From digital spatial data analysis using GIS-built versions of the hydrographic chart archive(spanning the years 1889-2005) accumulated by port authorities, both visual and net volumetric analysesof time-series Entrance Channel morphological changes have been made. Since the mid-1970s, channelsedimentation has imposed rising demands upon maintenance dredging regimes, which is a tendency thatparallels the decline in streamflow discharge from the Gippsland Lakes catchment, and correlates withthe introduction of specific sediment management regimes. Clear public policy implications emerge. Theyrefer to the continued need for provision of a navigable shipping channel that will also be of sufficientdepth to allow the escape to Bass Strait of any future catchment floodwaters. It is argued that adoptionof a spatial data intensive ‘Coastal Action Plan’ approach be considered in the future, to allow alreadyestablished Victorian State Integrated Coastal Zone Management (ICZM) policy to be brought into practice.

INTRODUCTIONMany ports and harbour developments world-wide refer to the relatively sheltered waters oftidal inlets, coastal lagoons and estuaries. Here, entrance and inner channel dimensions andconditions respond dynamically to physiographic processes (refer Bruun et al. 1978; Bruun andGerritsen 1960; Bird 1967) dominated by river discharge, tides (as manifest in the relative signi-ficance of ebb and flood tide volumes), winds, the nature and source of sediment, vulnerabilityto inundation (catchment flooding, storm surge overwash) and any engineered changes whichmay influence the balances between estuarine forces. In these terms, some coastal inlets will makebetter port locations than others. If regional economic growth calls for the provision of port fa-cilities, less than ideal coastal areas may have to be developed. In such areas, armouring, channeldredging and harbourside building must be engineered in ways that allow sustainability of portmaintenance. As a general rule, the need for maintenance works will be greater the more thenatural processes that characterised pre-development landscapes are interfered with.

One such harbour area that has been developed through long-term coastal modification issituated at Lakes Entrance, Victoria, Australia (refer Figure 1). Here, an artificial entrancechannel for the coastal lagoon system known as the Gippsland Lakes was first opened in June1889, so that coastal shipping could enter the Lakes system from Bass Strait. At first, navigationchannels were relatively easily maintained, as any flood-tide delta deposition was eventuallyswept away by seasonally occurring heavy catchment floodwater discharges, which considerably

ARTICLES

APPLIED GIS, VOLUME 2, NUMBER 1, 2006 MONASH UNIVERSITY EPRESS 05.1

augmented ebb-tidal flows. However, in the 116 elapsed years since 1889, Gippsland Lakescatchment water resource allocation has considerably changed (Wheeler 2005a). Alteration ofGippsland Lakes influent streamflow yields has taken place due to the effects of natural and/oranthropogenically induced climatic variability, urban, industrial and agricultural water use, andlarge-scale inter-regional water transfer schemes. Therefore, it is not surprising that seasonalebb-flow dominance at the Gippsland Lakes artificial entrance area has been progressively reducedin duration, and that the to-be expected flood-tide delta expansion and consolidation has takenplace. This changing dynamic balance has also placed increasing demands upon dredging regimes,which have been initiated primarily in attempts to maintain channel navigability.

Figure 1 Aerial oblique image of the Gippsland Lakes artificial entrance, and the township of Lakes Entrance.Author

Analogue-to-digital conversion of the hydrographic record for the artificial entrance area(from the period December 1889-January 2005) in a GIS (ESRI ArcGIS 9) has allowed the netlong-term changes in channel morphology to be three-dimensionally visualised and tabulatedvolumetrically (Wheeler 2005a; Wheeler and Peterson 2005a). Exploration of the likely causesof these visualised and tabulated time-series changes demands that the derived data be correlatedwith long-term catchment and coastal zone management information flowpaths, some of whichare held in archives by sectorally-administered catchment and coastal management agencies. Thistype of inter-sectoral data sharing and integration meets an essential requirement for the successful

SPATIAL INFORMATION FOR ICZM ARTICLES05.2

monitoring and resolution of coastal zone problems via integrated coastal zone management(ICZM) policy and practice.

INTEGRATED COASTAL ZONE MANAGEMENT (ICZM)The international importance and changing nature of coastal management, and the necessity ofincreasing sustainability in coastal development, was discussed at the United Nations Conferenceon Environment and Development (UNCED) held in Rio de Janeiro in 1992 (a meeting morecommonly referred to as the ‘Earth Summit’). Chapter 17 of Agenda 21 (United Nations Confer-ence on Environment and Development 1992) considered that the use of Integrated CoastalManagement (or sometimes called Integrated Coastal Zone Management (ICZM)) should becentral to the pursuit of global coastal area sustainability. Such an ‘integrated’ managementscenario attempts to consider concurrently the integrity of ecosystems, economic efficiency andsocial equity, including the rights of future generations (Young 1992) – a compromise which isessentially difficult to establish, especially in coastal areas. This difficulty is due to the operationof complex ecosystem webs which link the land, the sea, and the atmosphere; the expandingglobal human use of natural resources; and rapidly increasing human pressure on coastal areasaround the world (Vallega 1999).

The Intergovernmental Panel on Climate Change (1994, 25) consider ICZM as being:

The most appropriate process to address current and long-term coastal manage-

ment issues, including habitat loss, degradation of water quality, changes in

hydrological cycles, depletion of coastal resources, and adaptation to sea level

rise and other implications of climate change.

The United Nations Environmental Program (1995, 16) describes ICZM as:

An adaptive process of resource management for environmentally sustainable

development in coastal areas. It is not a substitute for sectoral planning, but

focuses upon the linkages between sectoral activities to achieve more compre-

hensive goals.

Since Australian adoption of Agenda 21, Federal and state policies (e.g. the 1995 Common-wealth Coastal Policy), and the 1995 Victorian Coastal Management Act) have promoted adoptionof an integrated approach to coastal zone management. The different types of stakeholder integ-ration (e.g. inter-governmental, inter-sectoral, science-managerial, private-public sector) requiredin an effective ICZM programme demand assembly and maintenance of large datasets of a diversenature in support of decision-making processes. As Cicin-Sain and Knecht (1998) relate, ICZMmust be based on sound scientific information from a range of disciplines before decisions willstand up to legal and political challenges. Such challenges are sure to be raised by interests whoseactivities may be affected by the ICZM process. It is recognised that different types of informationare required at different stages (e.g. during pre-implementation, implementation and operatingstages) (Douven et al. 2003) of the ICZM process. Clearly, the efficiency of any ongoing ICZMsystem will depend upon the provision of relevant and current information.

Much of the data and information used in decision support for ICZM is of a spatial nature.The use of Geographic Information Systems (GIS) as an ICZM ‘tool’ provides the capacity to

SPATIAL INFORMATION FOR ICZM ARTICLES 05.3

develop, process and display large amounts of data in ‘user-defined’ composition. The importanceof GIS for:

• Initial identification of coastal zone problems;• The enhancement of stakeholder understanding of coastal issues, and;• The provision of information for ICZM decision-making processes

has been exemplified in research by, amongst others, Hennecke et al. (2004), and Douven et al.(2003). GIS can also be used for the on-going monitoring and evaluation of coastal zone envir-onmental conditions, thus providing an ‘indicator’ mechanism by which assessment of progress,and measurement of governance performance, in integrated coastal zone management initiativescan be made (Ehler 2003; Olsen 2003). In addition, GIS deployment provides the potential foracquisition of common ‘mental maps’ (Gould and White 1974), and consensus building amongstvarious ICZM stakeholder groups (Poitras et al. 2003). After implementation of spatial datahandling such that scenario modelling at stakeholder meetings can be supported, comprehensivestakeholder ownership of coastal management problems can be advanced, and coastal zoneconflict resolution facilitated.

THE GIPPSLAND LAKES ARTIFICIAL ENTRANCE CHANNELThe 390 square kilometre coastal lagoon system known as the Gippsland Lakes is located between200 and 265 kilometers east of Melbourne, in the East Gippsland region (refer Figure 2). Threemain interconnected ‘lakes’ (Lakes Wellington, Victoria, and King), with many smaller arms andchannels, receive drainage from a 20,000 square kilometre catchment via the Thomson, Latrobe,Macalister, Avon, Mitchell, Nicholson and Tambo Rivers. The lakes are connected to Bass Straitvia an artificially engineered outlet (opened in June 1889), whose construction stimulated thedevelopment of the Lakes Entrance township. This artificial outlet is known as the EntranceChannel; it is bounded seaward by its outlet to Bass Strait, and landward by its confluence withthe Reeves and Hopetoun Channels, and the Cunninghame Arm (formerly known as ReevesRiver) (refer Figure 3).


Figure 2 The Gippsland Lakes Catchment, Victoria, AustraliaAuthor (Satellite photo source: Vicmap 2000, Landsat 7)


Figure 3 The Entrance Channel: locationAuthor


Prior to the extension of the Victorian railway network into East Gippsland, the GippslandLakes and inflowing streams served and freight and supply ‘conduits’ (Bird and Lennon 1989).In pre and immediate post-European settlement times (from 1838 onwards), a seasonal naturalentrance to the Gippsland Lakes existed near Red Bluff at the eastern extremity of the coastallagoon system (refer Figure 4). Ships would sail through this intermittent entrance from BassStrait when conditions permitted (Bird and Lennon 1989; Love 2004), and then along a channelknown as Reeves River (now known as Cunninghame Arm) into Lake King, and thence to theriver ports of Sale and Bairnsdale. During dry seasons, the natural entrance would sometimes beclosed off by sand for long periods to be later reopened by floodwaters during wet seasons. Thenature of the natural Gippsland Lakes entrance as encountered by some of the earliest Europeansin the area has been documented. For instance:

During the rainy season, and when the snow melts on the mountains, the lake

increases three to four feet in depth… At this season… the fresh water will have

sufficient force to clear away the sand on the bar, and… vessels may then pass

over it’. H.B. Morris, 1843 (Bird and Lennon (1989).

‘…the water rises to a great height in the lakes and the country for a distance

of one hundred miles back is flooded…the rush of waters very quickly cleared

a channel through which even large vessels could sail in’. W.T. Dawson, 1855

(Bird and Lennon (1989).

During heavy land-floods the stream runs continuously seawards [through the

natural entrance] for weeks; this fact was communicated to me both by Captain

Limesechow and Captain McAlpine who appear to have had greater experience

of the navigation through the entrance than any other persons. The former

mentioned an instance which occurred about six years since, when his schooner

was anchored about half a mile to seaward of the entrance; he stated that on

this occasion his vessel lay for eight days and nights with her head to the outgo-

ing current, and that the water running past, being quite fresh, was taken up

daily for ship’s use (Sir J.N.O. Coode 1879, 4).

Figure 4 The natural Gippsland Lakes entrance: 1879.A painting by Flora MinterCourtesy State Library of Victoria


Due to the requirement for a permanent navigable shipping link to facilitate the trade andsupply of goods between Melbourne and East Gippsland townships, works commenced on thedevelopment of an artificial entrance in 1869. The Royal Commission on Victorian Outer Ports(1927), published on 16 March 1927, notes that Mr. W.W. Wardell, the then Inspector Generalof Public Works, outlined and located the works forming the existing artificial entrance during1869, and his immediate successor, Mr. W.H. Steel, presided over works which commenced in1870 to excavate a 400 feet (121.9 m) wide cutting through the outer Holocene sandy barriersystem (now known as the Ninety Mile Beach). Works proceeded until 1874, and were tempor-arily halted after a heavy gale filled excavations with sand.

Bird and Lennon (1989) relate that in March 1878, Sir John Coode, a distinguished Englishcivil engineer, visited the Gippsland Lakes artificial entrance site after the Victorian State Gov-ernment reimbursed him a consultancy fee of £500. His task was to report and make recommend-ations on the project. This, he completed by December 1879. Coode related in this report thathe believed the entrance works were well sited, but that some changes should be made to theexisting training wall plans. He recommended that the ‘piers’ be extended some distance fromthe beach face – in the case of the western pier, 650 feet (198.1 m), and in the case of the easternpier, some 500 feet (152.4 m). He also noted that the training walls must be made to curveslightly to the south-west, making an angle of about 85º to the coastline, in order to ‘…turn theebbing currents more directly on to the waves which impinge on the foreshore’ (Coode 1879,6), and that the training walls should converge from 475 feet (144.8 m) wide at the lakes end to250 feet (76.2 m) wide in Bass Strait to concentrate ‘…the ebbing currents to a sufficient extentto produce the requisite velocity for keeping open the entrance’ (Coode 1879, 7).

Coode also considered it ‘…absolutely essential, for the maintenance of a sufficient depth inthe proposed entrance, that all connection between The Narrows, the North Arm, and ReevesRiver should be permanently and effectively cut off, except during periods of excessive flood’(Coode 1879, 7). He proposed that two barrier banks, constructed from rubble, should be em-placed across Reeves River (900 feet (274.3 m) in length), and between Bullock Island and themainland (320 feet (97.5 m) in length – across the North Arm). Initially, Coode recommendedthat these rubble walls should be low enough so that ‘extreme floods’ would overtop them andescape along Reeves River, and ‘might open out a small waterway near the site of the presententrance [near Red Bluff]’, but if this did not produce sufficient outflow to keep the entranceclear of sand, ‘…they should be raised so as to divert the flood discharge on all occasions throughthe new channel’ (Coode 1879, 7).

Coode further advised that:

…when the works have been completed to the full extent… a navigable depth

of about 12 feet [3.6 m] in the centre of the channel at low water will be

maintained on almost all occasions. Some little loss of depth will doubtless arise

from the disturbance of the sand bottom during periods of gales, but not to a

sufficient extent to impede the navigation in a material degree: and any slight

temporary accumulation of this character would be readily scoured away and

the full depth recovered upon the resumption of the normal condition of the

sea. By prolonging the piers, the permanent navigable depth in the entrance

channel would, as a matter of course, be increased, and the disturbing action


of gales on the sand bottom diminished, hence it is that I have indicated… [that]

two extensions to the arms, each of 175 feet [53.3 m] in length, which might

be undertaken hereafter when the trade on the lakes shall have grown to such

an extent, as no doubt it will eventually do, as to justify a further outlay (Coode

1879, 7-8).

Coode clearly believed that any departure from his planned scheme would prevent the entranceworks from achieving the desired effects: ‘… I am of the opinion that works of a lighter or lessextensive character would… fail to accomplish the object in view’ (Coode 1879, 9).

Bird and Lennon (1989) relate that in early June 1889, excavation works at the artificial en-trance were nearing completion. A wall comprising 12,000 sandbags had been emplaced at theseaward end of the works between the training walls, in an attempt to stop any inrush of seawaterand to ensure the entrance would eventually be opened by floodwaters, carrying excess sandsout to sea. The entrance training walls were composed of timber piles (which are still visibletoday – refer Figure 5), embedded to a depth sufficient to secure stability to withstand the anti-cipated scouring effects of the outflowing currents, and were strengthened at intervals by bulk-heads filled with rubble, so providing extra weight and stability. Works to emplace the rubblewall across Reeves River, planned by Sir John Coode, had also begun. However by Friday 14June 1889, a storm from Bass Strait forced open the sandbag wall. After a brief inrush of seawater,the high lake levels present at the time produced a strong outflow of water between the trainingwalls. Thus, the Entrance Channel was finally open (refer Figure 6), after a construction periodof nineteen years (1870-1889). The costs to construct the artificial entrance, and maintain it andother interior lakes waterways between the years 1870-1925, as estimated by the findings of the1927 Royal Commission, had totalled approximately £500,000 (Royal Commission on VictorianOuter Ports 1927, 4).

Figure 5 Original timber training walls adjacent to the eastern Gippsland Lakes artificial entrance pier head.Author


Figure 6 Sketch of the Gippsland Lakes artificial entrance, immediately after its opening to Bass Strait in1889.Courtesy State Library of Victoria

Despite Sir John Coode’s international reputation for port engineering (refer Bird and Lennon1989; Gourlay 1996), the plans that he was commissioned to prepare were not followed in theirentirety. The rubble walls across Reeves River and the North Arm, as proposed in the Coodescheme, were never constructed, and the 1927 Royal Commission report notes that other mater-ial departures from the Coode scheme included a widening of the dimensions between the entrancetraining walls at the seaward end (from 250 feet (76.2 m) to 275 feet (83.8 m)), and a considerableshortening of the training walls (by a combination of both unscheduled design and natural causes).By 1927, a crescent shaped sandbar (or ebb-tide delta) situated in Bass Strait offshore from theouter training wall ends had become established, with depths across it shoaling to 7 feet (2.1 m)where once there had been 35 feet (10.6 m) of water (Royal Commission on Victorian OuterPorts 1927, 13). This ebb-tidal delta persists to the present day (refer Figure 7), and has beenformed as sand, directed out to sea through the Entrance Channel in an ebb-tidal ‘jet’, falls fromsuspension. The natural longshore drifting processes along the Ninety Mile Beach, whose directionis largely dependent upon the prevailing swell wave conditions in Bass Strait, also provide asupply of sediment to the ebb-tide delta. If such sediment is not removed via longshore or offshoredrifting processes, formation of a ‘bar’ across a coastal lagoon or tidal inlet entrance will occur(McManus 2002).

The 1927 Royal Commission also suggested that rubble training walls be built at certainlocations in the Reeves Channel to promote increased ebb-flow velocities (refer Wheeler, 2005b);‘…the increased velocity of the scour through the Entrance which should result might have aconsiderable effect in cutting a channel through the bar’ (Royal Commission on Victorian OuterPorts 1927, 22). This suggestion, although departing from the original ‘Coode scheme’ (rubblewalls emplaced across the North Arm and Reeves River) was designed to produce the same effect;


that of increased ebb-tidal velocities in the Reeves and Entrance Channels. Some of the suggestedrubble training walls and groynes were finally constructed in the 1950s and 1960s. However,their long-term effects have proved to be negligible as Wheeler (2005b) suggests; their emplacementmay have caused a reduction in net ebb-tidal velocities and sediment entrainment capacity in theReeves and Entrance Channels, and across the ebb-tide delta in Bass Strait.

Figure 7 The ebb-tide delta (locally known as the ‘entrance sandbar’) in Bass Strait, immediately offshore the Entrance Channel,January 2005.Author

METHODOLOGY

HYDROGRAPHIC CHARTS

Since December 1889, hydrographic survey of the Gippsland Lakes artificial entrance area (ex-pressly of both the Entrance and Reeves Channels) has been carried out at regular intervals.Hydrographic survey is a mapping process, which is primarily concerned with fixing the positionof the coastline and of water depths, expressly for navigational rather than environmental mon-itoring or management purposes. However, for the study of long-term morphological change inestuaries or tidal inlets, these charts provide a valuable data source. This research study utilisesanalogue (paper) hydrographic survey charts of the Entrance Channel, representing the timeperiod 1889-2005, as a key primary dataset (refer Table 1).


Table 1 Entrance Channel hydrographic chart details, 1889-2005Author

Historically, three hydrographic survey methods have been used to obtain hydrographic datafrom the study area. Lead-line depth gauging techniques, in conjunction with the use of channelcross-lines between fixed points, or the use of sextants to determine horizontal (X, Y) positioning(Longden 2004) used for making earlier charts were superceded by deployment of electronicdepth sounding equipment (single frequency 200kHz) used in conjunction with the ‘Trisponder’electronic distance measuring system (Smith 2005). Since 1990, Global Positioning Systems (GPS)receivers have subsequently been interlinked with echo sounding equipment to compile hydro-graphic data used in chart complilation. Thus, the accuracy of hydrographic data collectionmethods has varied since 1889. A comprehensive survey of the relative accuracy of each methodof hydrographic data gathering has been provided by van der Wal and Pye (2003). Hydrographiccharts created after 1968 have been subject to standards, set by the International HydrographicOrganisation (IHO), which are designed to reduce error in hydrographical data. Advances insatellite positioning and sonar systems led to a review of these standards in 1998 (refer Mills1998). Survey data obtained since this time must be evaluated against these new IHO standards(refer International Hydrographic Organisation 1998).

The depth values taken during hydrographic surveys and denoted on hydrographic chartsmust be corrected to represent the same water level (known as a vertical datum). This aspect isessential due to the influence of vertical water level fluctuations on hydrographic vessels duringsoundings data acquisition. Until 1975, study area hydrographic charts employed the British


Admiralty datum known as ‘Low Water Ordinary Spring Tides’ (LWOST) (Admiralty 1975).After 1975, most hydrographic charts utilised for this study employed the locally derived datum‘0.537/0.543 meters below Australian Height Datum (AHD)’. Investigation into the correlationbetween this figure (-0.537m/-0.543m AHD) and LWOST by Port of Melbourne Corporationstaff has revealed that both datums are sufficiently similar (+/- 50mm) so as to allow all hydro-graphic charts used in this study to be directly comparable in time series without any adaptationof recorded depth values (Longden 2004; Smedts 2004).

DIGITAL DATABASE CONSTRUCTION

All suitable hydrographic charts were digitised using a professional quality high-resolutionscanner at 400 dpi, to output data in CAL, JPEG or TIFF image formats. Subsequent digitisationwas carried out using the GIS software ESRI ArcGIS 9 (e.g. see Wheeler 2005b). A conciseproject process flow diagram is provided at Figure 8. The horizontal datum chosen for use inthis study was the Geocentric Datum of Australia 1994/Map Grid of Australia Zone 55 (GDA94MGA Zone 55). The accuracy concerns with the use of Grid DEMs referred to by Chang (2004,147) and Burrough and McDonnell (2000, 230-2) led to the use of only TIN DEMs throughoutthis research project.

Figure 8 Project Process Flow Diagram.Author


DATA ANALYSIS

After conversion of DEMs to ‘layer files’ (thus reflecting a common depth value colour ramp),direct visual comparison of images is facilitated. Resultant time-series two and three-dimensionalDEM visualisations can be displayed in different ways so ‘mental maps’ of bathymetric evolutioncan be standardised among relevant coastal zone stakeholder groups.

In time-series, these visualisations, promote the diffusion of knowledge about:

• Entrance Channel bathymetric evolution;• The influence of physiographic processes on Entrance Channel morphology;• The influence of extreme environmental forcings events (e.g. floods) on bathymetric evolution,

and;• The effectiveness of Entrance Channel dredging regimes

It is the ‘Cut and Fill’ function of GIS software (in this case, located in ESRI 3D Analyst)that enables convergence of all data processing for derivation of model-dependent net time-seriesvolumetric change: in the case of the present study, the Entrance Channel bathymetric change.Using this tool, the morphological change represented in a pair of TIN DEMs can be comparedso that volumetric (m³) differences can be calculated. Construction of an Entrance Channel Cutand Fill ‘analysis mask’ (refer Figure 9) allowed uniform sections of the Entrance Channel toundergo Cut and Fill analysis. Thus, time-series Entrance Channel DEMs could be readily com-pared to one another, revealing the amount of net sediment gain or loss between successive hy-drographic surveys.

It should be noted that all area and volumetric figures derived from Cut and Fill analysis ofstudy area DEMs are model dependent: the snap-shots represented in the time-series facilitatedetection of net change between arbitrarily set times. The proximity of hydrographic data surveytimings to dredging operation timings can never be quantified, and this is a variable factor thatshould be considered when interpreting data on net volumetric change. The seasonal timings ofhydrographic surveys must also be considered, because the operation of dynamic environmentalforcings/regimes (and their effects upon channel bathymetry and sediment volumes) will differbetween surveys. Thus, the linear volumetric gain/loss trend between DEM ‘snap-shots’ refersto net change only.

RESULTS

TIME-SERIES VISUALISATION OF ENTRANCE CHANNEL BATHYMETRIC EVOLUTION

Just six months after its opening to Bass Strait (in December 1889), the first hydrographic surveyof the Entrance Channel was undertaken. Visualisations of the Entrance Channel for this initialsurvey (refer Figure 10) show the effects of ebb-flow scouring upon channel bathymetry, withsmall ‘scour-holes’ being prominent along the entire channel floor. From its confluence with theHopetoun Channel, the Entrance Channel is deepest along the concave eastern training wall; asMorisawa (1985, 91-2) relates, the centreline of natural channel flow will move towards theouter (concave) bank, as a result of minimum variance or least work principle. At the entrance‘throat’ between the eastern and western pier heads in Bass Strait, a deep scour hole has formed.Visualisations for 1892 (refer Figure 11) clearly show that overall Entrance Channel depths had


increased since the initial survey, and that channel depths generated by ebb-flow scouring havevisibly exceeded the recommended depths envisaged by Sir John Coode in 1879 (a 12 feet (3.6m)) deep fairway and side depths of 9 feet (2.7 m)). The 1927 Royal Commission findings notethis occurrence:

A few years after the opening of the channel, when the piers extended seaward

nearly in accordance with the designed lengths of the Coode Scheme, unforeseen

and startling results were experienced…. Instead of a concave channel providing

a 12-feet [3.6 m] deep fairway and side depths of 9 feet [2.7 m], … a depth of

25 feet [7.6 m] developed at the inner or lakes end of the channel, and at the

outer or sea end the scour cut down to a depth of 85 feet [25.9 m] (Royal

Commission on Victorian Outer Ports 1927, 9).

Figure 9 Entrance Channel ‘Cut and Fill’ analysis mask: location.Author


Figure 10 2D and 3D digital images of the Entrance Channel for 1889. Depth legend in metres.Author


Figure 11 2D and 3D digital images of the Entrance Channel for 1892. Depth legend in metres.Author

From the visualisations shown it is seen that Entrance Channel depths have been maintainedover the period 1892-1941 (refer Figure 12). A deep ebb-flow scour hole has intermittently de-veloped at the Entrance/Hopetoun Channel confluence (visible 1892, 1941). An overall shallowingof Entrance Channel depths can be noted in the visualisation for 1964, with this trend continuing


to 1989 (refer Figure 13). Sediment loss in the Entrance Channel is visible over the period 1991-1992 (refer Figure 14), followed by a period of overall net accumulation to January 1998 (referFigure 15). To this date, the Entrance Channel was visibly shallower than at any stage in itshistory of 109 years. A large sand spit in the Entrance Channel (adjacent to the western entrancepier head) had developed, clearly constricting the Entrance Channel at this point; indeed, it isvisible above the high water mark (refer Figure 16).

Figure 12 2D and 3D digital images of the Entrance Channel for 1914, 1926 and 1941. Depth legend in metres.Author


Figure 13 2D and 3D images of the Entrance Channel for 1964, 1987 and 1989. Depth legend in metres.Author


Figure 14 2D and 3D images of the Entrance Channel for 1991 and 1992. Depth legend in metres.Author


Figure 15 2D and 3D images of the Entrance Channel for 1993, 1994 and pre-floods 1998. Depth legend in metres.Author


Figure 16 Extensive sand spit development in the Entrance Channel adjacent to the western entrance training wall pier head,January 1998.Author

During and after a major catchment flood event (22-24 June 1998) (refer Tan et al. 2002;Wheeler 2005c; Wheeler and Peterson 2005b), floodwaters were held back before escapingthrough the artificial entrance to Bass Strait (refer Figure 17) partly by accumulation of flood-tide delta sands in the Reeves and Entrance Channels. Analysis of environmental conditionsprevailing at the time of the June 1998 floods reveals that floodwater levels were sustained notonly by channel constriction, but by a convergence of what Tan et al. (2002) labels as environ-mental ‘forcings’ (dominated by streamflows, but modified by tides, winds and atmosphericpressure gradients).

The visualisation for the channel (1 July 1998) shows that extensive post-flood sediment losshas taken place. Visual comparison of pre/post-1998 flood oblique images allows the extent ofbathymetric change to be comprehended (refer Figure 18). Post-flood (May 1999-January 2005)visualisations (refer Figure 19) show that sediment accumulation continued within the channelbetween July 1998 and July 2000, followed by sediment loss between 2000-2003. Sediment ac-cumulation is then apparent in the visualisations for the interval 2003-2005. This sediment accu-mulation trend over the period January 1998-January 2005 occurred despite the progressive in-stallation and operation since January 1999 of a Sand Transfer System by Gippsland Ports (referFigure 20), and dredging from time to time by the side-cast dredger April Hamer at the confluencebetween the Cunninghame Arm and the Entrance Channel (refer Figure 21).


Figure 17 Floodwaters from the June 1998 Gippsland Lakes flooding event escaping via theEntrance Channel to Bass Strait, late June 1998.Courtesy East Gippsland News, Bairnsdale, Victoria

Figure 18 Comparative 2D and 3D images of the Entrance Channel, taken from pre/post-1998 flood DEMs. Depth legend in metres.Author


Figure 19 2D and 3D images of the Entrance Channel for 1999, 2000 and 2005. Depth legend in metres.Author


Figure 20 The Lakes Entrance Sand Transfer System (STS).Courtesy Gippsland Ports (2005a)

Figure 21 The Gippsland Ports side-cast dredger April Hamer pictured during dredging operations at theconfluence of the Cunninghame Arm and the Entrance Channel, January 2006.Author


Comparisons between oblique visualisations of entrance throat bathymetry for 1914 and1999 (refer Figure 22) shows net change, from a maximum depth of 21.5 metres (70.5 feet) inSeptember 1914, to a maximum depth of 7 metres (23 feet) in May 1999.

Figure 22 Comparative 3D images of the Entrance Channel throat bathymetry for1914 and 1999. Depth legend in metres.Author


TIME-SERIES ENTRANCE CHANNEL BATHYMETRY VOLUMETRIC CHANGE

Cut and Fill volumetric analysis quantifies the findings from visual analysis of the displays astwo and three-dimensional TIN DEMs. Derived estimated volumetric change figures providedat Table 2 and Figure 23 show that extremely rapid net estimated sediment loss took place inthe Entrance Channel between December 1889 and June 1892, whilst between 1892 and 1941each period surveyed (1892-1914; 1914-1926; 1926-1941) showed slow net estimated sedimentaccretion. By 1941, sediment accumulation in the channel had not yet refilled it to its December1889 levels. Clearly, the forces (e.g. see Bird 2000: 236-7) determining the dimensions of theEntrance Channel remained in relative balance over this period.

In the 23 elapsed years between 1941 and 1964, a period of increased net estimated sedimentaccumulation took place in the Entrance Channel. During this interval, sediment accretion finallyreplaced the sediment lost through ebb-flow scouring over the period 1889-1892. During thenext 23-year interval between surveys (1964-1987), a net estimated sediment accretion trendtook place. This trend has continued between March 1987 and January 2005, excepting isolatedcases of net estimated sediment removal (May 1989 – December 1992, June 1993 – July 1994,pre/post-floods 1998, and July 2000 – September 2003), and despite the removal from the Reevesand Entrance Channels of a recorded sediment total of approximately 1,000,000 m³ in sandtransfer/sand bypass operations (refer Table 3). An example of a derived Cut and Fill model ofthe Entrance Channel (extracted from within the analysis-masked area), which shows the locationsof volumetric change between survey intervals, is provided at Figure 24.

Table 2 Estimated net Entrance Channel volumetric change figures, 1889-2005.Author


Figure 23 Graph of estimated net Entrance Channel volumetric change figures, 1889-2005.Author

Table 3 Sediment Transfer System (STS) Operational Figures, January 1999 – January 2005.Courtesy Slurry Systems (Marine) Pty. Ltd.


Figure 24 Location of Entrance Channel estimated net sediment gain/loss, derived through Cut and Fill modelling (in this example, forthe time-series interval 2000-2005).Author

DISCUSSIONCombination of Entrance Channel bathymetric change data (both visual and quantitative)presented in this paper with similar data for the upstream Reeves Channel, researched byWheeler (2005b) and Wheeler and Peterson (2005a) shows that sediment accumulation in boththe Reeves and Entrance Channels has been inexorable over the period 1975-2005 (refer Table4). Such morphometric change refers to a reduction of catchment streamflows due to inter-re-gional water diversion schemes, in particular, via the Thomson Dam scheme (capacity 1.068GL), which supplies water for domestic and industrial use in metropolitan Melbourne. By inter-cepting and diverting the naturally occurring seasonally higher (May – December) upper-Thomson River discharges (refer Figure 25), the Thomson Dam (commissioned in 1983) hascontributed to a loss of streamflow augmentation of ebb-flows at the Gippsland Lakes artificialentrance area. Other major contributors to a loss of streamflow augmentation of ebb-flows include


Table 4 Entrance and Reeves Channels – estimated net sediment volumetric gain/loss, 1889-2005.Source: Wheeler and Peterson (2005a)

Figure 25 Pre/post Thomson Dam changes in Thomson River streamflows (upstream of Cowwarr Weir, North/Central Gippsland).Source: Thomson Macalister Environmental Flows Task Force (2004)


catchment water diversion from the Tanjil River via the Blue Rock Dam (capacity 208,000 ML),from the Thomson River (downstream of Thomson Dam) via Cowwarr Weir, and from theMacalister River via Lake Glenmaggie (capacity 190,410 ML). Primarily, the waters impoundedby Lake Glenmaggie and Cowwarr Weir are used for irrigation purposes within the MacalisterIrrigation District, situated to the northwest of the Victorian regional township of Sale (referFigure 26).

Figure 26 Aerial oblique photograph of Lake Glenmaggie and northerly parts of the Macalister Irrigation District, July 2005.Author

Added to the effects of water transferral schemes, it has been documented by Wheeler (2005a)that over the past 30 years, Gippsland Lakes catchment rainfall and streamflows (from all majorinfluent streams) have experienced falling yield trends. These falling yields may have also beenfurther reduced by aerosol cloud pollution from up-wind urban and industrial sources (e.g. fromMelbourne and Adelaide), which can alter rain-producing processes (Rosenfeld 2000). Fallingrainfall trends have been noted in such situations in other parts of the world (e.g. see Givati andRosenfeld, 2004). Thus, total inflow forcings (combined streamflows and rainfall) at the studyarea have been progressively reduced since 1889. In addition, research by Wheeler (2005a), andFryer (1971), shows that seasonally, evaporation of water from the Gippsland Lakes may exceedthe amount supplied by total inflows (combined streamflows and rainfall) for long periods, attimes removing all fluvial influent augmentation of ebb-tidal currents. During such periods, thescope for inner-channel sediment accretion is greatly enhanced (refer Figure 27).


Figure 27The estimated relationship between total inflows and evaporation (1997-1998) at the Gippsland Lakes artificial entrance area shows thatevaporation exceeded total inflows between November 1997 and May 1998. Reduced total inflow augmentation of ebb-tidal currents wouldhave been the result, with associated decreased amounts of sediment scouring and removal at the artificial entrance area.Source: Wheeler (2005a). Streamflow data: Tan and Grayson (2002); Evaporation data: Bureau of Meteorology (2004).

That any reduction in ebb-tide velocity will affect sedimentation patterns in the vicinity ofcoastal lagoon or tidal inlet entrances has been noted by many authors, including Bird (1967;Bird 1984), Ippen (1966), Bruun et al. (1978), Bruun and Gerritsen (1960) and Davies (1980).Bird (2000, 237-8) relates that the configuration of a lagoon entrance is the outcome of a contestbetween the currents that flow in and out and the effects of longshore drift of sand, which tendto seal them off. Bruun et al. (1978) relate that any tidal inlet on a shore subject to littoral driftis perpetually in a state of dynamic equilibrium because the relative significance of tidal flow,waves and littoral drift volume (and in some cases, as with the Ninety Mile Beach, drift direction)are changeable. In this context, the authors note that the main causes of tidal inlet shoaling(seaward or landward of the inlet opening, or both) include:

• Prolongation of the inlet channel or channels;• Overwhelming deposits of littoral-drift material, particularly during [and after] severe storms

(refer Figure 28);• Splitting up the main inlet channel into two or more channels, or formation of one or more

channels from natural or artificial causes;• Change in bay area from which water flows into the inlet (e.g. by the construction of dams).


Figure 28An oblique aerial photograph (taken in January 2006 at an altitude of 3000ft AMSL, one day after a severe southwesterly gale episode of three days duration)showing sediment enriched flood-tide flows entering the Gippsland Lakes via the artificial entrance. These sediments were ‘stirred’ into suspension in thecoastal water column along the Ninety Mile Beach via the operation of southwesterly swell waves and longshore drift.Author, January 2006

Another potential contributor to channel infilling is sediment management regime changes.At Lakes Entrance, this occurred after the deployment of the side-cast dredger April Hamer,which has been almost permanently operational in the artificial entrance area since 1977 (referFigure 29). The dredging methods of the April Hamer are considered by Bird (2000, 238) toenhance flood-tidal delta nourishment within the inner channels. In sediment transport terms,the side-cast dredging operation promotes continued suspension of sediment throughout thewater column. In these terms, sand dredging simulates the surf-zone suspension that takes placewhen high-energy waves break. In both cases, the scope for flood tide sand entrainment to augmentthe volume of the flood-tide delta is enhanced. A 1973 report of feasibility for side-cast dredgingat Lakes Entrance by the US Army Corps of Engineers stated that:

It is emphasised that the effectiveness of the sidecasting technique diminishes

as the project dimensions increase because of loss of current velocities through

the [tidal] prism. Ultimately a point is reached where it is no longer economical

to utilise the sidecasting technique alone (Baggerman Associates Pty Ltd 1973).


Figure 29 The April Hamer in side-cast dredging operations at the ebb-tide delta area, September 2004.Author

The rise and fall of the tide at the entrance mouth, and the associated exchange of watermasses through the entrance result in the temporary storage of a progressively larger volume ofseawater within the inner channels during the flood tide, and the drainage of this water seawardduring the ebb tide; the total sea water volume involved in this oscillation is known as the tidalprism (Ippen, 1966). O’Brien (1931) appears to have been one of the first to investigate the rela-tionship between the dimensions of an entrance and the tidal prism along sandy coasts. Ippen(1966) further relates that of significance in relation to the retreating (ebb-tide) tidal prism is thecontinual inflow of fresh water from upland sources, which mixes with seawater stored in theinner channels at high tide, and thus augments ebb-tidal discharges seaward through the entrance(refer Figure 30). Progressive loss of tidal prism augmentation through reduction of catchmentfresh water inflows can be expected to reduce the scouring effect of the ebb tide in the Entranceand Reeves Channels. Maintenance dredging of the kind currently practiced at Lakes Entrance(refer Figure 31) can also alter the tidal prism volume; as O’Brien (1931) suggests, if depositionof dredged materials between low and high water levels is not compensated for by increasedchannel depth, reduction in the tidal prism and a deterioration of entrance dimensions is to beexpected.

Gippsland Lakes fresh water inflow reduction trends (via the inter-regional and catchmentwater diversion schemes) imply that a proportion of the bathymetric changes described in thispaper relate directly to upland catchment management. The Gippsland Lakes catchment is subject


to management by many agencies, including Melbourne Water, the East and West GippslandCatchment Management Authorities (CMAs), Southern Rural Water, The Gippsland CoastalBoard, Gippsland Ports, the Victorian Department of Sustainability and Environment, and LocalGovernment Agencies (LGAs). The entire Gippsland Lakes catchment is positioned under thejurisdiction of the Gippsland Coastal Board.

Structural arrangements for coastal planning and management in Victoria are provided forby the Victorian Coastal Management Act (1995). Its stated objectives are:

• To plan for and manage the use of Victoria’s coastal resources on a sustainable basis for re-creation, conservation, tourism, commerce, and similar uses in appropriate areas;

• To protect and maintain areas of environmental significance on the coast, including its eco-logical, geomorphological, geological, cultural and landscape features;

• To facilitate the development of a range of facilities for improved recreation and tourism;• To maintain and improve coastal water quality, and;• To improve public awareness and understanding of the coast and to involve the public in

coastal planning and management.

Figure 30Aerial photograph (taken 26 April 2002 from an altitude of 9000 ft AMSL) showing ebb-tide augmentation by Gippsland Lakes catchment fresh waterstreamflows (ebb-tidal flow through the artificial entrance can be discerned by the discoloured (brown) water). Note direction of longshore drift along theNinety Mile Beach is easily discernable, and in this case is to the east. Southwesterly swell wave trains can also be noted in the photograph.Photo: courtesy B. Smedts, Gippsland Ports


Figure 31The April Hamer during side-cast dredging operations in the Reeves Channel (between Rigby and Bullock Islands), January 2005. Side-cast dredge spoil istemporarily re-distributed in the channel system some 25-30 metres from the dredge point under this method of dredging. It is possible that this spoil isquickly redistributed back to the dredged areas via the action of tidal currents.Author

These objectives are consistent with the concepts of ICZM (refer Cicin-Sain and Knecht,1998, and Vallega, 1999) and ecologically sustainable development (ESD) (Commonwealth,1992). To implement these main objectives, the Act establishes two levels of agencies: the Vic-torian Coastal Council (VCC), responsible for preparation of a major strategic planning document(the Victorian Coastal Strategy, or VCS), and three separate Regional Coastal Boards, responsiblefor implementing the VCS on a regional basis, and preparing Coastal Action Plans (CAPs) afterconsultation with local stakeholder groups (refer Figure 32). Wescott (2004) relates that CAPsare statutory planning documents under the Act, and are intended to integrate the statewideperspective of the VCS and the locally based and derived management plans and planning schemes.Under the Act, CAPs can be based on large geographic areas (such as the entire Gippsland Lakescatchment), incorporating many management plans.

According to the VCC (2006), CAPs are designed to identify strategic directions and objectivesfor use and development in a region. They provide for detailed planning of the region or part ofthe region to facilitate recreational use and tourism, and to provide for protection and enhance-ment of significant features of the region's coast, including the marine environment.


Figure 32Conceptual map of current Victorian Coastal Management Structure. In the Gippsland Lakes catchment, the Gippsland Coastal Boardis responsible for implementing the VCS and for preparation of CAPs.Author

Since its inception under the Act, the Gippsland Coastal Board has been active in the catchmentpromoting sustainability; for instance, through its membership of the Thomson Macalister En-vironmental Flows Task Force. In February 2004, this Task Force produced a strategy for iden-tification and deployment of environmental flow options for the Thomson and Macalister Rivers.However, in the final conclusions and recommendations section, no mention has been made ofthe links between sedimentation at the Gippsland Lakes artificial entrance area, and streamflowdischarge reductions from the Thomson/Macalister River systems to the Gippsland Lakes. Thus,the opportunity for accepting responsibility for the impact of upstream water diversion uponcoastal dynamics at the artificial entrance has been ignored to the present.

It is argued that sharing the derived digital spatial information assembled for the researchproject reported here offers a basis for establishing on-call decision support for bringing catchmentICZM strategies to practice, so that sustainable long-term solutions to the problems imposedupon the Gippsland Ports Authority by channel sedimentation may be found through stakeholderconsensus building. The Gippsland Coastal Board, in working towards assembly of a compre-hensive and integrated Coastal Action Plan, including inputs from all Gippsland Lakes catchmentstakeholder groups at State, regional and local levels, is in a position to provide both ‘horizontal’and ‘vertical’ integration of data and information flows in decision support. Through utilisationof an integrated ‘Coastal Action Plan’ approach, it is suggested that a revenue stream to support


a sustainable long-term sediment management strategy at the artificial entrance may be found.For instance, if it were accepted by catchment stakeholders that progressive streamflow diversionshave contributed to (and will continue to contribute to) sediment management difficulties at theartificial entrance area, development of a compensation system for the loss of ‘ecological services’which were provided by natural streamflows at the artificial entrance area may provide a realisticrevenue stream in support of a sustainable sediment management strategy. The need for a sus-tainable sediment management regime not only refers to the efficient removal of sediment fromchannels to ensure safe navigation, but also refers to the need to alleviate the flood risk to theLakes Entrance township that current levels of channel constriction in the Entrance and ReevesChannel have imposed (e.g. refer Wheeler 2005c; Wheeler and Peterson 2005b; Grayson et al.2004; McMaster 1998).

It is probably impossible for Gippsland Lakes catchment authorities to reinstate naturalstreamflow regimes in the future, so as to re-establish ebb-tidal sediment scouring at the artificialentrance area. A combination of factors apply: the need for water storage to cater for futureVictorian and Gippsland climate change scenarios (refer Whetton et al. 2000; Department ofSustainability and Environment 2005), industry commitments (e.g. water provision for catchmentirrigation schemes and Latrobe Valley power station requirements), and provision of metropol-itan Melbourne’s current and projected future water needs (refer Water Resources StrategyCommittee 2002). On 5 January 2006, the Victorian Minister for Water, Mr. John Thwaites,announced in a media release (Victorian Government 2006) that under the West Gippsland RiverHealth Strategy, increased water releases from the Thomson Dam into the lower Thomson Riverwould be initiated for the next five years (2006-2011), and would be sourced from a 10,000ML‘environmental entitlement’, allocated by the State Government from ‘water savings’ (via waterrestrictions) in Melbourne over the years 2004-2005. Although Mr. Thwaites claimed that this‘extra release of water to the Thomson River is replicating the natural season river flow’, it isapparent after reference to Figure 25 that the new flow regime will not be sufficient to indeedimitate natural seasonal high flow periods along the entire stream channel (from the headwatersto the Gippsland Lakes), and as such will probably have little influence in the promotion of in-creased sediment scouring at the Gippsland Lakes artificial entrance area. This argument is sup-ported after reference to the West Gippsland Catchment Management Authority website, whereit is stated that during water release periods:

Rises in river height of up to 0.7 metres can be expected in the upper reaches

of the Thomson River [below the Thomson Dam]. Natural system losses, such

as evaporation and groundwater interaction, mean that changes in river height

through the lower reaches, below Cowwarr Weir, will be reduced. Due to the

complex interaction of water with the environment these changes are difficult

to predict.

It remains clear that deliberations over any future sediment management scenarios for the artificialentrance area will, by necessity, centre upon the use of coastal engineering options. On 10November 2005, the Victorian State ALP Government announced an $AU31.5 million packageto ‘install a sand management system to keep the Lakes Entrance port open’ (Victorian Govern-ment 2005). However, it remains to be seen whether the proposed sand management program


trials (refer Kowarsky and Associates 2005; Gippsland Ports 2006) will be either effective orsustainable (environmentally and/or economically) in the long-term.

It is interesting to note that the 1927 Royal Commission Report suggested that ‘a return tothe Coode conception’ (Royal Commission on Victorian Outer Ports 1927, 9) may be requiredat the artificial entrance because ‘…the shortened piers [entrance training walls, in relation tothe Coode scheme dimensions] have proved ineffective, and the only remedy seems to lie in ex-tension of the piers seaward’ (11). Both the Engineer for Ports and Harbours of the day, Mr. C.Kermode, the Assistant Engineer for Ports and Harbours and Marine Surveyor, Mr. T.H. Smith(22), and the proposed harbour works drawings from the Royal Commission Report (Appendix5) suggest that the entrance training walls be extended into Bass Strait in conformity with theCoode scheme. In the ‘Suggested Future Works’ section of this report (23), Mr. T.H. Smith’ssuggestions are noted. It is stated that:

Harbour works, even when designed on correct lines, are expensive undertak-

ings, and the greatest care and investigation would be necessary to arrive at

correct marine interpretations, and so avoid again sinking large sums in hopeless

and wasteful experimental works.

From existing marine conditions it would seem natural to assume to get better

permanent working depths on the bar the piers would require lengthening by

about 500 to 600 feet at least… On this basis, the cost of extending the… [en-

trance training walls, (in 1927), would total some] £204,000’.

These recommendations have not been followed to the present, and have (to date) not beenofficially considered as part of any future proposed sediment management strategy by GippslandPorts (refer Kowarsky and Associates 2005; Gippsland Ports 2006). Given the current hydro-dynamic conditions present at the artificial entrance area, aspects of the original Coode scheme,including extended entrance ‘piers’, and the narrowing of entrance dimensions between the outerpier heads to produce a ‘funnelling’ of ebb-flows, may be considered even more necessary afterprogressive reduction of ebb-tide velocities since 1927. It is worth relating Coode’s own viewpoint,considered earlier in this paper:

… I am of the opinion that works of a lighter or less extensive character would

… fail to accomplish the object in view (Coode 1879, 9).

And also the viewpoint of the Commissioners of the 1927 Royal Commission Report:

…after all that has been spent on them, the works at the Gippsland Lakes en-

trance are practically useless for serving the purpose for which they were de-

signed (Royal Commission on Victorian Outer Ports 1927, 23).

Should future management officially consider extending the existing entrance training wallsfurther into Bass Strait, any such deliberations must also consider the installation of a sedimentbypass system, designed with sufficient capacity to imitate natural longshore drift processes alongthe Ninety Mile Beach. However, it should be noted that especially during and after storm eventsalong the Ninety Mile Beach, the amount of natural longshore sediment transport (refer Figure


28) may be far in excess of the maximum capacity of any installed sediment transfer system tohandle. Various assessments to date of gross and net littoral transport volumes along the NinetyMile Beach are provided at Table 5. It is essential that enough sediment be moved down-driftthrough any proposed bypass system, in order to nourish beaches and to remove the possibilityof any serious beach erosion occurring.

Table 5 Gross/net littoral drift estimates – Ninety Mile BeachSources: Buckley (1990); Port Authority Gippsland (1994); Foster (1995); Coastal Engineering Solutions (2003).

In both environmental and managerial/political terms, much could be learnt by reference tothe Tweed Heads (New South Wales, Australia) case study, where the coastal management re-sponse to the interruption of littoral drift of sand by training walls at the mouth of the TweedRiver has resulted in a joint agreement between the N.S.W. and Queensland State Governmentsfor installation of a sand bypassing system. This system pumps sand accumulated on the N.S.W.side of the training walls northwards into the Queensland littoral zone (e.g. refer Dyson et al.2001; Dyson et al. 2002; Boswood, et al. 2001; Lawson et al. 2001). Reference to other sandbypassing projects world-wide (e.g. refer Boswood and Murray 2001) may also provide valuablelessons to guide future sand bypassing project development and installation at Lakes Entrance.

CONCLUSIONSBoth visual and volumetric analyses of DEMs for the Entrance Channel for the period December1889 – January 2005 shows that:

• An initial phase of rapid sediment loss took place between 1889 - 1892;• Sediment then accumulated slowly until 1941, signifying that a dynamic balance was main-

tained within the Entrance Channel between ebb and flood tidal flows;• Within the period 1941 - 1964, Entrance Channel sediment accretion increased. This trend

has continued over the period 1964 - January 2005, despite recorded sediment loss over somehydrographic survey intervals.

• A progressive reduction in tidal prism volume (including progressive reduction of tidal prismaugmentation by upland streamflows) has occurred over the period December 1889 – January2005.


The magnitude of the overall time-series flood-tide delta accumulation trend can be obtainedwhen Entrance Channel sediment volumetric gain/loss data is combined with similar data forthe Reeves Channel. This trend can be correlated with an increase in catchment water diversionand catchment climatic variation/change, and has occurred despite the introduction of variouspublicly funded sand management regimes at the artificial entrance area in the post-1977 period.Removal of sediment by current and proposed future management strategies refers to the needto provide a navigable channel system for shipping, and to allow for floodwater escape to BassStrait throughout any future Gippsland Lakes catchment flooding events.

Reference to the case study examined in this paper shows that a ‘gap’ between ICZM policyand practice can be considered as currently occurring within the Gippsland Lakes catchment. Itis through the deployment of digital spatial data handling that such ‘gaps’ can be initially identi-fied, and steps taken by catchment stakeholders to formally address coastal zone problems. Inthis case, adoption of a ‘Coastal Action Plan’ approach, designed to address the channel sediment-ation problem at the Gippsland Lakes artificial entrance through implementation of ICZM initi-atives, is one method by which a sustainable long-term solution to the problem may be found.This approach would require much input from relevant stakeholder agencies at State, regionaland local levels for the development and implementation of integrated management strategies.Underpinning such an approach, time-series digital spatial data would be collected and madeaccessible for ICZM decision-support and monitoring at all relevant levels. A three-dimensionalintegrated catchment and coastal zone scenario modelling approach, as exemplified in this researchpaper, holds much potential for rapid promotion of coastal zone stakeholder understanding andconsensus building. Further application of this rapid and defensible decision support method isclearly called for in future management of the Gippsland Lakes artificial entrance area.

ACKNOWLEDGEMENTSThe assistance of the following organisations and individuals is gratefully acknowledged:Gippsland Ports and the Port of Melbourne Corporation, for primary hydrographic data provision,in particular Port of Melbourne Corporation staff member Mr Greg Longden, and GippslandPorts staff members Mr Bertrand Smedts, Mr. Peter Hinksman, Mr. Geoff Kohlman, Ms GailBolding, and Mr Alan Smith; academic staff at the Centre for GIS, School of Geography andEnvironmental Science, Monash University, Melbourne; Mr Lex Nankervis, Slurry SystemsMarine; Mr Ray Wheeler for assistance in aerial photography acquisition, and the anonymousacademic referees of this paper.

REFERENCESAdmiralty. 1975. Admiralty Tidal Handbook 2: Datums for Hydrographic Surveys (and other related

subjects). Taunton: Hydrographic Department.Baggerman and Associates Pty. Ltd. ‘Report of feasibility study sidecasting dredge for State of Victoria’

Report prepared by the Marine Design Division, US Army Engineer District Philadelphia. July 1973.In Review of dredging for Victorian local ports: Final report, produced by Baggerman AssociatesPty. Ltd. in association with Evers Consulting for the Department of Natural Resources andEnvironment, Coastal and Ports Policy Branch, September 1998.

Bird, E.C.F. 1967. ‘Coastal lagoons in southeastern Australia’. In Landform studies from Australia and NewGuinea, edited by Jennings, J.N.; Mabbutt, J.A. Canberra: ANU.


Bird, E.C.F. 1984. Coasts: An introduction to coastal geomorphology. 3rd edn. Canberra: ANU.Bird, E.C.F. 2000. Coastal geomorphology: An introduction. New York: Wiley.Bird, E.C.F.; Lennon, J. 1989. Making an entrance: The story of the artificial entrance to the Gippsland

Lakes. Bairnsdale, Victoria: James Yeates Printing.Boswood, P.K.; Murray, R.J. 2001. World-wide sand bypassing systems: data report. Conservation technical

report No. 15 (R20). Queensland: Queensland Government Environmental Protection Agency.Boswood, P.; Victory, S.; Lawson, S. 2001. ‘Placement strategy and monitoring of the Tweed River entrance

sand bypassing project nourishment works’. A paper presented at the 15th Australasian Coastal AndOcean Engineering Conference (8th Australasian Port and Harbour Conference). 25–28 September;Gold Coast, Queensland.

Bruun, P.; Gerritsen, F. 1960. Stability of coastal inlets. Amsterdam: North Holland Publishing Co.Bruun, P.; Mehta, A.J.; Johnsson, I.G.; 1978. Stability of tidal inlets: Theory and engineering. Developments

in Geotechnical Engineering 23. Amsterdam: Elsevier Scientific Publishing Company.Buckley, R. 1990. ‘Assessment of Coastal Regime: Lakes Entrance Bar’. Report No. 90-0225. Melbourne:

Marine Laboratory Port of Melbourne Authority.Bureau of Meteorology. 2004. ‘Victorian climate data’. [Internet]. Australian Government. Accessed 18

November 2005. Available from www.bom.gov.au.Burrough, P.; McDonnell, R. 2000. Principles of geographic information systems. New York: Oxford

University Press.Chang, K. 2004. Introduction to geographic information systems. New York: McGraw-Hill.Cicin-Sain, B.; Knecht, R. 1998. Integrated coastal and ocean management. Concepts and Practices.

Washington: Island Press.Coastal Engineering Solutions. 2003. ‘Lakes Entrance bar and channel dynamics: Sand management report

final study’. A report prepared for Gippsland Ports, December 2003.Coode, J.N.O. 1879. ‘Gippsland Lakes Entrance’. A consultancy report written for Victorian Ports and

Harbours, December 1879.Commonwealth of Australia. 1992. National Strategy for Ecologically Sustainable Development. Canberra:

Australian Government Publishing Service.Commonwealth of Australia. 1995. Commonwealth Coastal Policy. Canberra: Australian Government

Publishing Service.Davies, J.L. 1980. Geographical Variation in Coastal Development. 2nd edn. New York: Longman.Department of Sustainability and Environment. 2005. ‘Climate change in East Gippsland’. [Internet]. Victorian

Government. Accessed September 2005. Available from:http://www.greenhouse.vic.gov.au/impacts/media/East_Gippsland.pdf.

Douven, W; Buurman, J; Kiswara, W. 2003. ‘Spatial information for coastal zone management: The exampleof the Banten Bay seagrass ecosystem, Indonesia’. Ocean and Coastal Management. 46: 615–634.

Dyson, A.; Victory, S.; Connor, T. 2001. ‘Sand bypassing the Tweed River entrance: An overview’. Paperpresented at the The 15th Australasian Coastal and Ocean Engineering Conference (8th AustralasianPort and Harbour Conference). 25–28 September: Gold Coast, Queensland.

Dyson, A.; Lawson, S.; Victory, S.; Boswood, P.; Mahon, B.; Trucchi, L.; Cummings, P. 2002. ‘Tweed Riverentrance sand bypassing project post commissioning coastal behaviour’. Paper presented at the 28thInternational Conference on Coastal Engineering - Solving Coastal Conundrums. 7–12 July: Cardiff,UK.

Ehler, C.N. 2003. ‘Indicators to measure governance performance in integrated coastal management’. Oceanand Coastal Management. 46: 335–345.

Foster, D.N. 1995. ‘Options for the improvement to Lakes Entrance, Victoria’. Report to the Port AuthorityGippsland Region no. 895, August: Gippsland.

Fryer, J.J. 1971. Gippsland Lakes entrance investigation, Vol. 1. Victoria: Public Works Department, Portsand Harbours Division.


http://www.bom.gov.au/

http://www.greenhouse.vic.gov.au/impacts/media/East_Gippsland.pdf

Gippsland Ports. 2005a. ‘Diagram of sand transfer system, Lakes Entrance’. Paper prepared by GippslandPorts.

Gippsland Ports. 2005b. ‘Update on sand management program for Lakes Entrance’. [Internet]. GippslandPorts. Available from:http://www.gippslandports.vic.gov.au/GK%20051216%20Update%20on%20Sand%20Management%20Program.pdf.

Gippsland Ports. 2006. ‘Lakes Entrance sand management program 2006-2010: draft implementation plan– subject to agency endorsement’. [Internet]. A report prepared by CorpSupport Pty Ltd. Accessed30 March 2006. Available from:http://www.gippslandports.vic.gov.au/LESMP%20Implementation%20Plan_30%20March%2006.pdf.

Givati, A; Rosenfeld, D. 2004. ‘Quantifying precipitation suppression due to air pollution’. Journal of AppliedMeteorology. 43: 1038–1056.

Gould, P.; White, R. 1974. Mental maps. London: Penguin.Gourlay, M.R. 1996. ‘History of coastal engineering in Australia’. In History and heritage of coastal

engineering, edited by Kraus, N.C. New York: American Society of Civil Engineers: 1–80.Grayson, R.; Candy, R.; Tan, K.S.; McMaster, M.; Chiew, F.; Provis, D.; Zhou, S. 2004. ‘Gippsland Lakes

flood level monitoring project’. Report 01/04. Melbourne: Centre for Environmental AppliedHydrology (University of Melbourne).

Hennecke, W; Greve, C; Cowell, P; Thom, B.G. 2004. ‘GIS-based coastal behavior modelling and simulationof potential land and property loss: Implications of sea-level rise at Collaroy/Narrabeen beach,Sydney (Australia)’. Coastal Management 32 (4): 449–470. DOI: 10.1080/08920750490487485.

International Hydrographic Organisation. 1998. IHO standards for hydrographic surveys. IHO SpecialPublication No. 44. 4th edn.

Intergovernmental Panel on Climate Change. 1994. ‘Preparing to meet the coastal challenges of the 21st

century’. Report of the World Coast Conference. November. The Hague, Netherlands. Ministry ofTransport, Public Works and Water Management.

Ippen, A.T., editor. 1966. Estuary and coastline hydrodynamics. New York: McGraw-Hill.Kowarsky and Associates. 2005. ‘Draft long term management plan for dredging 2005-2015’. A report

prepared for Gippsland Ports. March.Lawson, S.; McMahon, J.; Boswood, P. 2001. ‘Environmental management of the construction and operation

of a sand bypassing system at the Tweed River Entrance’. Paper presented at The 15th AustralasianCoastal and Ocean Engineering Conference; The 8th Australasian Port and Harbour Conference.25–28 September. Gold Coast, Queensland, Australia.

Longden, G. 2004. Personal communication. Senior surveyor, Port of Melbourne Corporation. 25 May.Love, D. 2004. Shipwrecks on the East Gippsland Coast. Melbourne: D. Love and Heritage Victoria.McManus, J. 2002. ‘Deltaic responses to changes in river regimes’. Marine Chemistry. 79: 155–170.McMaster, M. 1998. Modelling the hydrodynamics of Lakes Entrance. Unpublished 4th year environmental

engineering research Project. The University of Melbourne.Mills, G. 1998. ‘International hydrographic survey standards’. International Hydrographic Review. 75 (2):

79–85.Morisawa, M. 1985. Rivers: form and process. New York: Longman.Nankervis, L. 2005. ‘Lakes Entrance dredging and sand bypassing records’. A report prepared by Slurry

Systems Pty Ltd (Marine). Lakes Entrance, Gippsland.O’Brien, M.P. 1931. ‘Estuary tidal prism related to entrance areas’. Civil Engineering. 1 (8): 738–739.Olsen, S.B. 2003. ‘Frameworks and indicators for assessing progress in integrated coastal management

initiatives’. Ocean and Coastal Management. 46: 347–361.Poitras, J; Bowen, R; Wiggin, J. 2003. ‘Challenges to the use of consensus building in integrated coastal

management’. Coastal and Ocean Management. 46: 391–405.


http://www.gippslandports.vic.gov.au/GK 051216 Update on Sand Management Program.pdf

http://www.gippslandports.vic.gov.au/GK 051216 Update on Sand Management Program.pdf

http://www.gippslandports.vic.gov.au/LESMP Implementation Plan_30 March 06.pdf

Port Authority Gippsland. 1994. ‘Information Note 94/01’. Port Authority Gippsland Information Note.Gippsland, Victoria.

Rosenfeld, D. 2000. ‘Suppression of rain and snow by urban and industrial air pollution’. Science. 287: 1793.Royal Commission on Victorian Outer Ports. 1927. ‘The Gippsland Lakes Entrance and Gippsland’s

development generally’. Fifth progress report, 16 March 1927. Melbourne: Government Printer.Smedts, B. 2004. Personal communcation. Ports engineer, Gippsland Ports, Bairnsdale. 21 May.Smith, A. 2005. Personal communication. Ports manager, South Gippsland, Gippsland Ports. 16 February.Southern Rural Water. 2005. ‘Capacity information for Blue Rock Dam and Lake Glenmaggie’. [Internet].

Southern Rural Water. Available from: www.srw.com.au.State Library of Victoria. 2005 . Various images of the Gippsland Lakes natural and artificial entrances.

Available from: www.slv.vic.gov.au.Tan, K.S.; Grayson, R.B. 2002. ‘Environmental database for the Gippsland Lakes flood modelling project’.

Draft report prepared for CEAH, Department of of Civil & Environmental. Engineering, TheUniversity of Melbourne. Melbourne.

Tan, K.S.; Grayson, R.; Chiew, F.; McMahon, T.; A. Western. 2002. ‘Exploring cross-correlations ofenvironmental forcings in a coastal lagoon’. Paper submitted to 27th Hydrology and Water ResourcesSymposium. 20–23 May. Melbourne, Australia.

Thomson Macalister Environmental Flows Task Force. 2004. ‘Environmental flow options for the Thomsonand Macalister rivers: final report – conclusions and recommendations’. Thomson MacalisterEnvironmental Flows Task Force. Traralgon.

United Nations Conference on Environment and Development. 1992. Agenda 21 and the UNCED Proceedings.New York: Oceana Publications.

United Nations Environmental Program. 1995. Guidelines for integrated management of coastal and marineareas. UNEP Regional Seas Reports and Studies. Split, Croatia: United Nations EnvironmentalProgram.

Vallega, A. 1999. Fundamentals of integrated coastal management. London: Kluwer Academic Publishers.van der Wal, D; Pye, K. 2003. ‘The use of historical bathymetric charts in a GIS to assess morphological

change in estuaries’. The Hydrographic Journal. 110: 3–9.Victorian Coastal Council. ‘The Victorian Coastal Strategy and Coastal Action Plans’. Available from:

http://www.vcc.vic.gov.au/strategy/index.htm.Victorian Coastal Management Act. 1995. Victorian Government, Melbourne.Victorian Government. 2005. ‘Provincial statement to boost jobs and growth: funding to keep Lakes Entrance

Port open’. Media release.Victorian Government. 2006. ‘Thomson River flowing strongly’. Media release. 5 January.Water Resources Strategy Committee for the Melbourne Area. 2002. ‘Final report – summary: 21st century

Melbourne: A watersmart city’.Wescott, G. 2004. ‘The theory and practice of coastal area planning: linking strategic planning to local

communities’. Coastal Management. 32: 95–100.West Gippsland Catchment Management Authority. 2006. ‘Environmental water reserve – Thomson River’.

Available from: http://www.wgcma.vic.gov.au/default.asp?action=page&catID=18&pageID=264.Wheeler, P.J. (2005a) Morphometric Change in the Entrance and Reeves Channels of the Gippsland Lakes

(1889-2005): Implications for Integrated Coastal Zone Management. Unpublished Honours thesis,School of Geography and Environmental Science, Monash University.

Wheeler, P.J. 2005b. ‘Bathymetric evolution at a coastal inlet after channel edge groyne emplacement: a casestudy from the Gippsland Lakes, Victoria, Australia’. Applied GIS. 1 (3): 28.1–28.34. DOI10.2104/ag050028.

Wheeler, P.J. 2005c. ‘Analysis of pre/post flood event bathymetric change using a GIS: A case study fromthe Gippsland Lakes, Victoria, Australia’. Applied GIS. 1 (3). 24.1-24.29. DOI 10.2104/ag050024.


http://www.srw.com.au/

http://www.slv.vic.gov.au/

http://www.vcc.vic.gov.au/strategy/index.htm

http://www.wgcma.vic.gov.au/default.asp?action=page&catID=18&pageID=264

Wheeler, P.J.; Peterson, J.A. 2005a ‘Volumetric change in a flood-tide delta: application of the ‘Cut and Fill’process flow diagram for decision support in port management at Lakes Entrance, Victoria, Australia’.Refereed paper, Proceedings of SSC2005 Spatial Intelligence, Innovation and Praxis: The NationalBiennial Conference of the Spatial Sciences Institute. 12–16 September. Melbourne Exhibition andConference Centre. 552-561.

Wheeler, P.J.; Peterson, J.A. 2005b. ‘Environmental and institutional pre-cursors to natural disasters: a casestudy of the June 1998 Lakes Entrance floods’. Paper presented at the International SymposiumDisaster Reduction on Coasts: Scientific-Sustainable-Holistic-Accessible. 14–16 November. MonashUniversity. Melbourne, Australia.

Whetton, P.H.; Hennessy, K.J.; McGregor, J.L.; Katzfey, J.J.; Page, C.M.; Nguyen, K. 2000. ‘Fine resolutionassessment of enhanced greenhouse climate change in Victoria: Annual report 1995–96’. CSIROatmospheric research consultancy report for Victorian Department of Natural Resources andEnvironment. Melbourne.

Young, M.D. 1992. Sustainable development and resource use: Equity, environmental integrity and economicefficiency. Man and biosphere series, volume 9. Paris: UNESCO and Parthenon Publishing Group.

Cite this article as: Wheeler, Peter: ‘Spatial information for Integrated Coastal Zone Management (ICZM):An example from the artificial Entrance Channel of the Gippsland Lakes, Australia’. Applied GIS 2 (1). pp.5.1–5.45. DOI: 10.2104/ag060005.


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Spatial information for Integrated Coastal Zone Management ... · of a spatial data intensive ‘Coastal Action Plan’ approach be considered in the future, to allow already established