Journal articles on the topic 'Causeway Lake'

Kamaniskeg Lake is a long, narrow, and deep small lake located in the northern part of Ontario, Canada. The goals of this paper were to examine various options to improve the water quality in the northern part of the lake by altering the local hydraulic flow conditions. Towards this end, a preliminary screening suggested that the flow circulation could be increased around a central island (Mask Island) in the northern part of the lake by opening up an existing causeway connecting the mainland and central island. Three-dimensional (3D) hydraulic and transport models were adopted in this paper to investigate the hydraulic conditions under various wind forces and causeway structures. The modelling results show that opening the causeway in a few places is unlikely to generate a large flow circulation around the central island. Full circulation only appears to be possible if the causeway is fully removed and a strong wind blows in a favourable direction. The possible reasons for existing water quality variations at the intake of a local WTP (water treatment plant) are also explored in the paper.

A traffic causeway placed on the sediments of saline Tramping Lake failed during construction in the summer of 1982. Vertical subsidence has continued until present (1988). The failure mechanism was controlled by sedimentary structure and artesian groundwater conditions. The shear zone is in a soft, near normally consolidated lacustrine sandy silt unit 22 m thick. The lake basin contains lacustrine, deltaic, and fluvial deposits of postglacial origin. Artesian conditions in the Upper Cretaceous Judith River Formation and postglacial fluvial sand and gravel dominate the hydrogeology at the site. The failure took place along a composite slip surface when excess pore-water pressures developed during loading [Formula: see text]. The estimated effective friction angle from triaxial tests and back calculation was 27° assuming c′ = 0. However, a parametric analysis showed that at very high pore-water pressures the effective friction angle required for equilibrium is very sensitive to small variations in ru. The calculated cohesion at [Formula: see text] required for equilibrium was 3.9 kPa, whereas the remolded vane strength measured in the field was 5.0 kPa. Key words: Foundation failure, artesian, saline environment, groundwater discharge, silty clays, postglacial fluvial and lacustrine deposits.

Stratified flows and the resulting density-driven currents occur in the natural environment and commonly in saline lakes. In the Great Salt Lake, Utah, USA, the northern and southern portions of the lake are divided by an east-to-west railroad causeway that disrupts natural lake currents and significantly increases salt concentrations in the northern section. To support management efforts focused on addressing rising environmental and economic concerns associated with varied saltwater densities throughout the lake, the causeway was recently modified to include a new breach. The purpose of this new breach is to enhance salt exchange between the northern and southern sections of the lake. Since construction, it typically exhibits a strong density-driven bidirectional flow pattern, but estimating flows and salt exchange has proven to be difficult. To obtain much needed insights into the ability of this hydraulic structure to exchange water and salt between the two sections of the lake, a field campaign coupled with CFD modeling was undertaken. Results from this study indicate that the vertical velocity profile in the breach is sensitive to density differences between flow layers along with breach geometry and water surface elevations. The CFD model was able to accurately represent the bidirectional flows through the breach and provides for improved estimates of water and salt exchanges between the north and south sections of the lake.

ABSTRACT Urmia Lake is a large-scale hypersaline lake that experienced a drastic water-level fall due to natural and anthropogenic forces during the last two decades. Construction of a causeway in the central part of the lake after 1989 has divided the lake into northern and southern parts and caused an extreme change of the lake hydrochemical system. Precipitation of evaporite minerals as crust on the lake floor was caused by the combination of lake level fall and increasing water salinity. However, some parameters controlling rates of salt deposition and dissolution and temporal and spatial variation in salt thickness in Lake Urmia are poorly understood. This study reviews 90 sediment cores from various parts of the lake to put forward a better understanding of the salt depositional system and salt thickness variations in the basin for the last 40 years (1977–2017). Our results indicate that the sedimentary system of Urmia Lake changed rapidly during the last two decades from a permanent hypersaline lake with predominantly fast terrigenous–biochemical sedimentation to a seasonally changing playa sedimentary environment with predominance of evaporite minerals. These changes are responsible for rapid salt deposition that generated a salt-crust with a maximum thickness of 2.95 m overlying Holocene terrigenous sediments. The salt-crust thickness and the water depth have a positive correlation for water depth greater than 1 meter, which means that salt-crust thickness increases where water depth increases. While the thickness of shallow deposits are affected by fresh-water dissolution. In addition, the average salt precipitation rate in the northern and the southern parts of the lake is 466 and 266 times higher, respectively, than the average (0.3 mm/y) sedimentation rate before the lake shrinkage. Similar to other large hypersaline lakes such as the Great Salt Lake (USA) and the Aral Sea (Central Asia), the manmade intervention at Urmia Lake (damming of the catchment, extension of agricultural fields, and causeway construction in the middle part of the lake) threatens its further hydrologic existence.

Construction of a causeway bridge on the Lake Urmia accelerated the drying trend of the largest hyper-saline lake of the world. The objective of the research is to investigate the differences of precipitation and river discharge before and after initiation of the construction of the bridge in 2000. The study area was the watershed of the lake. The averages of the precipitation data in the two periods before and after the project have been interpolated by IDW based on GIS Geostatistical Analyst. The two interpolated precipitation layers were used to be plugged into Student T-test equation in GIS in a spatial basis. To do this, the study area was divided to 25 regions based on drainage sub-basins. Less than 30 sample areas were randomly selected as cases from each of the regions to put into the equation. The discharge data were also compared for the two periods. The results indicated that except in some limited areas, the precipitation differences in the two periods are significant. This means that there were little changes in precipitation and river discharge in the area and consequently the drying may be caused mainly by hydrodynamic changes in the lake due to construction of the causeway. However, it can be argued that the changes in the lake’s surface area are accompanied by changes in precipitation and river discharge. The t test statistic can be applied samples based on spatial analysis.

Urmia Lake in the northwestern of Iran is a hypersaline water body and has become an environmentally important issue especially due to the presence of an infrequent aquatic species, Artemia Urmiana. During the last three decades, several considerable man-made changes including river damming and construction of a causeway across the lake affected the lake salinity. This article aims to propose a new approach of salinity modeling using a reduced-order model based on MIKE21 simulation model, in conjunction with principal component analysis (PCA) technique. At first, spatial variation of salinity in the lake was simulated by MIKE21 to prepare the input information for the PCA. Then, the dominant modes of salinity were determined by PCA technique while MIKE21 simulated results were compared with the output of developed reduced order model. Findings indicated that MIKE21's results closely matched the experimental data collected by field study. Also, the first 10 PCs among 974 modes computed by the reduced order model conserved approximately over 93% of the system variance. Therefore, the reduced order model was sufficient to capture the variation of salinity in the lake using a few first PCs. In other words, it was generally found that improvements in the simulated salinity in the lake provided by reduced order model were comparable to MIKE21 simulations.

In the village of Beşköprü, about five kilometres to the south-west of the town of Adapazari in western Turkey, and just to the north of the main Istanbul–Ankara highway, there stands a large well-constructed bridge; its fabric is generally in good condition apart from the destruction of a short section of the causeway near its eastern end to permit the passage of the branch railway line to Adapazan. Although the bridge now only spans two minor side channels of the small stream called the Çark Deresi, which drains Lake Sophon (modern Sapanca), there is no doubt that the bridge was originally designed on the orders of the emperor Justinian to span the mighty Sangarius (modern Sakarya) which at present flows in a south–north direction about three kilometres to the east of the bridge. The only detailed first-hand account of the bridge is still that by Texier, whose description has to be corrected on some important points.

Frame Lake, located within the city of Yellowknife, Northwest Territories, Canada, has been identified as requiring significant remediation due to its steadily declining water quality and inability to support fish by the 1970s. Former gold mining operations and urbanization around the lake have been suspected as probable causes for the decline in water quality. While these land-use activities are well documented, little information is available regarding their impact on the lake itself. For this reason, Arcellinida, a group of shelled protozoans known to be reliable bioindicators of land-use change, were used to develop a hydroecological history of the lake. The purpose of this study was to use Arcellinida to: (1) document the contamination history of the lake, particularly related to arsenic (As) associated with aerial deposition from mine roaster stacks; (2) track the progress of water quality deterioration in Frame Lake related to mining, urbanization and other activities; and (3) identify any evidence of natural remediation within the lake. Arcellinida assemblages were assessed at 1-cm intervals through the upper 30 cm of a freeze core obtained from Frame Lake. The assemblages were statistically compared to geochemical and loss-on-ignition results from the core to document the contamination and degradation of conditions in the lake. The chronology of limnological changes recorded in the lake sediments were derived from 210Pb, 14C dating and known stratigraphic events. The progress of urbanization near the lake was tracked using aerial photography. Using Spearman correlations, the five most significant environmental variables impacting Arcellinida distribution were identified as minerogenics, organics, As, iron and mercury (p < 0.05; n = 30). Based on CONISS and ANOSIM analysis, three Arcellinida assemblages are identified. These include the Baseline Limnological Conditions Assemblage (BLCA), ranging from 17–30 cm and deposited in the early Holocene >7,000 years before present; the As Contamination Assemblage (ACA), ranging from 7–16 cm, deposited after ∼1962 when sedimentation began in the lake again following a long hiatus that spanned to the early Holocene; and the Eutrophication Assemblage (EA), ranging from 1–6 cm, comprised of sediments deposited after 1990 following the cessation of As and other metal contaminations. The EA developed in response to nutrient-rich waters entering the lake derived from the urbanization of the lake catchment and a reduction in lake circulation associated with the development at the lake outlet of a major road, later replaced by a causeway with rarely open sluiceways. The eutrophic condition currently charactering the lake—as evidenced by a population explosion of eutrophication indicator taxa Cucurbitella tricuspis—likely led to a massive increase in macrophyte growth and winter fish-kills. This ecological shift ultimately led to a system dominated by Hirudinea (leeches) and cessation of the lake as a recreational area.

The effect of retrofitting an existing pond on removal efficiency and hydraulic performance was modelled using the commercial software Mike21 and compartmental modelling. The Mike21 model had previously been calibrated on the studied pond. Installation of baffles, the addition of culverts under a causeway and removal of an existing island were all studied as possible improvement measures in the pond. The subsequent effect on hydraulic performance and removal of suspended solids was then evaluated. Copper, cadmium, BOD, nitrogen and phosphorus removal were also investigated for that specific improvement measure showing the best results. Outcomes of this study reveal that all measures increase the removal efficiency of suspended solids. The hydraulic efficiency is improved for all cases, except for the case where the island is removed. Compartmental modelling was also used to evaluate hydraulic performance and facilitated a better understanding of the way each of the different measures affected the flow pattern and performance. It was concluded that the installation of baffles is the best of the studied measures resulting in a reduction in the annual load on the receiving lake by approximately 8,000 kg of suspended solids (25% reduction of the annual load), 2 kg of copper (10% reduction of the annual load) and 600 kg of BOD (10% reduction of the annual load).

One of the unusual features of Lakes Fryxell and Hnare in Taylor Valley, southern Victoria Land, Antarctica, is their perennial ice cover. This ice cover limits gas exchange between the atmosphere and the lake water, and causesa very stable stratification of the lakes. We analyzed a series of water samples from profiles of these lakes and their tributaries for δ13C of the dissolved inorganic carbon (DIC) in order to qualify the carbon flux from the streams into the lakes, and to investigate the carbon cycling with in the lakes. Isotopic values in the uppermost waters (δ13C = +l.3‰ to 5.3‰ in Lake Hoare, +0.4‰ to +3.0‰ in Lake Fryxell) are close to the carbon-isotope values encountered in the streams feeding Lake Fryxell, but distinctively heavier than in streams feeding Lake Hoare (δ13C= — 2.3%n to 1.4%). These ratios are much heavier than ratios found in the moat that forms around the lakes injanuary February (δC = -10.1%). in the oxic photic zones of the lakes, photosynthesis clearly influences the isotopic composition, with layers of high productivity having enriched carbon-isotope signatures δ13C= +2.7‰ to +6.1‰). in both lakes, the isotopic values become lighter with depth, reaching minima of 3.2‰ and 4.0% in Lakes Fryxell and Hoare, respectively. These minima are caused by the microbial remineralization of isotopically light organic carbon. We present DIC flux calculations that help to interpret the isotopic distribution. For example, in Lake Hoare the higher utilization of CO2aq, and a substantially smaller inflow of CO2 from streams cause the heavier observed isotopic ratios. Differences in the hydrology and stream morphologies of the tributaries also greatly influence the carbon budgets of the basins.

AbstractThe Skiddaw Group in the Cross Fell inlier comprises the Catterpallot Formation of latest Tremadoc or earliest Arenig age, the Murton Formation of Arenig age, and the Kirkland Formation of early Llanvirn age. Each of these formations can be correlated with formations in the Skiddaw Group of the Lake District. The faulted contact of the Catterpallot and Kirkland formations is the probable extension of the Causey Pike Fault (CPF), which separates two distinct sequences in the Skiddaw inlier of the northern Lake District. Contrasts across the CPF in the Cross Fell inlier reflect those seen in the Skiddaw inlier. The CPF is a major basement structure, separating markedly different successions in the Ordovician strata of northern England.

We present a multiproxy study of land use by a pre-Columbian earth mounds culture in the Bolivian Amazon. The Monumental Mounds Region (MMR) is an archaeological sub-region characterized by hundreds of pre-Columbian habitation mounds associated with a complex network of canals and causeways, and situated in the forest–savanna mosaic of the Llanos de Moxos. Pollen, phytolith, and charcoal analyses were performed on a sediment core from a large lake (14 km2), Laguna San José (14°56.97′S, 64°29.70′W). We found evidence of high levels of anthropogenic burning from AD 400 to AD 1280, corroborating dated occupation layers in two nearby excavated habitation mounds. The charcoal decline pre-dates the arrival of Europeans by at least 100 yr, and challenges the notion that the mounds culture declined because of European colonization. We show that the surrounding savanna soils were sufficiently fertile to support crops, and the presence of maize throughout the record shows that the area was continuously cultivated despite land-use change at the end of the earth mounds culture. We suggest that burning was largely confined to the savannas, rather than forests, and that pre-Columbian deforestation was localized to the vicinity of individual habitation mounds, whereas the inter-mound areas remained largely forested.

AbstractRegional variation of white mica (illite) crystallinity in the Skiddaw Group is set against the structural interpretation of Hughes, Cooper & Stone (1993, this issue) in which early- or pre-Ludlow deformation and slaty cleavage development (S1) were succeeded by southward thrusting and an associated development of S1 and S1 crenulation cleavages, possibly during early Devonian times. Kubier index (KI) values are plotted in relation to geological structure for a major part of the Skiddaw Group, and cross-sections constructed. The pattern is interpreted in terms of three processes: (1) diagenetic to low anchizonal burial metamorphism under a relatively high geothermal gradient during the late-arc stage (early to mid-Silurian) which preceded the orogenic phase and formation of S1; (2) upper anchizonal to epizonal metamorphism due to tectonic thickening and slaty cleavage development during the early to pre-Ludlow orogenic phase following closure of Iapetus; (3) late-tectonic uplift of already metamorphosed rocks by southward-directed movement on the Loweswater, Gasgale Gill and Causey Pike Thrusts possibly during early Devonian time. An analogous interpretation is made for the Skiddaw area, though with the addition of major post-S1 contact metamorphism.

AbstractGreat Salt Lake of Utah is among the largest and most ecologically important water bodies in North America. Since the late 1950s, the lake has been divided into two hydrologically distinct water bodies by a rock-fill railroad causeway. Flux through the causeway is driven by two forces: differential surface elevation and differential density between the north and south arms. The south arm features episodic vertical stratification due to the influx of deep, dense brine from the north arm. The source of this brine (a breach, two culverts, or subsurface flow) has been investigated over the past 50 years. Quantification of subsurface water flux through the causeway has been problematic due to the heterogeneous and slowly compacting nature of the causeway fill over time. Between 2008 and 2015, enhanced gauging of various surface inflows and outflows and density measurements made throughout the lake permitted detailed water volume calculations of both lake arms. Results show that during high precipitation years, density-driven, north-to-south flow through the causeway predominates due to freshening of water in the south arm. At other times, south-to-north head gradient driven flow and north-to-south density-driven flow are approximately equal. The model suggests subsurface flux through the causeway is one important driver of the ecologically important deep brine layer in the south arm of the lake over the past 20 years.

The Spotted Turtle (Clemmy guttata), a small freshwater turtle species, prefer shallow wetland habitats, and are restricted to eastern North America, predominantly in southern Ontario along the southern shores of the Great Lakes. However, the Spotted Turtle has been classified as ‘vulnerable’ (a species of special concern) by COSEWIC since 1991, owing to the 35% decline of the population throughout the past century. This is primarily of concern regarding reductions of ecosystem biodiversity, and further anthropogenic pressures will drive the species towards further endangerment. High rates of road mortality are considered a key actor in facilitating a decline in the Spotted Turtle population. A study by Ashley and Robinson (1996) found that approximately 25% of annual Spotted Turtle deaths are a direct result of roadway incidents, around the Long Point Causeway, bordering Lake Erie. By utilizing data from Long Point, the extent of road mortality of the Spotted Turtle will be characterized by analyzing the proportions of deaths in high-density versus low-density roadways. There is varied response to the effectiveness of various solutions to minimize road mortality, including a vegetation management approach boarding roadways, subterranean passages, barriers along roadsides, and influencing and informing in decision-making processes. With the Sandy Pines Wildlife Center, Napanee, reductions in roadway mortality rates will decline along the 401 by increasing both public and private sector awareness regarding the issue of Spotted Turtle road mortality. Recommendations to communities and government entities will be made to facilitate the improvement of the status of Spotted Turtle.

Special Care Notice This article contains images of deceased people that might cause sadness or distress to Aboriginal and Torres Strait Islander readers. Introduction Like many cities, Perth was founded on wetlands that have been integral to its history and culture (Seddon 226–32). However, in order to promote a settlement agenda, early mapmakers sought to erase the city’s wetlands from cartographic depictions (Giblett, Cities). Since the colonial era, inner-Perth’s swamps and lakes have been drained, filled, significantly reduced in size, or otherwise reclaimed for urban expansion (Bekle). Not only have the swamps and lakes physically disappeared, the memories of their presence and influence on the city’s development over time are also largely forgotten. What was the site of Perth, specifically its wetlands, like before British settlement? In 2014, an interdisciplinary team at Edith Cowan University developed a digital visualisation process to re-imagine Perth prior to colonisation. This was based on early maps of the Swan River Colony and a range of archival information. The images depicted the city’s topography, hydrology, and vegetation and became the centerpiece of a physical exhibition entitled Re-imagining Perth’s Lost Wetlands and a virtual exhibition hosted by the Western Australian Museum. Alongside historic maps, paintings, photographs, and writings, the visual reconstruction of Perth aimed to foster appreciation of the pre-settlement environment—the homeland of the Whadjuck Nyoongar, or Bibbulmun, people (Carter and Nutter). The exhibition included the narrative of Fanny Balbuk, a Nyoongar woman who voiced her indignation over the “usurping of her beloved home ground” (Bates, The Passing 69) by flouting property lines and walking through private residences to reach places of cultural significance. Beginning with Balbuk’s story and the digital tracing of her walking route through colonial Perth, this article discusses the project in the context of contemporary pressures on the city’s extant wetlands. The re-imagining of Perth through historically, culturally, and geographically-grounded digital visualisation approaches can inspire the conservation of its wetlands heritage. Balbuk’s Walk through the City For many who grew up in Perth, Fanny Balbuk’s perambulations have achieved legendary status in the collective cultural imagination. In his memoir, David Whish-Wilson mentions Balbuk’s defiant walks and the lighting up of the city for astronaut John Glenn in 1962 as the two stories that had the most impact on his Perth childhood. From Gordon Stephenson House, Whish-Wilson visualises her journey in his mind’s eye, past Government House on St Georges Terrace (the main thoroughfare through the city centre), then north on Barrack Street towards the railway station, the site of Lake Kingsford where Balbuk once gathered bush tucker (4). He considers the footpaths “beneath the geometric frame of the modern city […] worn smooth over millennia that snake up through the sheoak and marri woodland and into the city’s heart” (Whish-Wilson 4). Balbuk’s story embodies the intertwined culture and nature of Perth—a city of wetlands. Born in 1840 on Heirisson Island, Balbuk (also known as Yooreel) (Figure 1) had ancestral bonds to the urban landscape. According to Daisy Bates, writing in the early 1900s, the Nyoongar term Matagarup, or “leg deep,” denotes the passage of shallow water near Heirisson Island where Balbuk would have forded the Swan River (“Oldest” 16). Yoonderup was recorded as the Nyoongar name for Heirisson Island (Bates, “Oldest” 16) and the birthplace of Balbuk’s mother (Bates, “Aboriginal”). In the suburb of Shenton Park near present-day Lake Jualbup, her father bequeathed to her a red ochre (or wilgi) pit that she guarded fervently throughout her life (Bates, “Aboriginal”).Figure 1. Group of Aboriginal Women at Perth, including Fanny Balbuk (far right) (c. 1900). Image Credit: State Library of Western Australia (Image Number: 44c). Balbuk’s grandparents were culturally linked to the site. At his favourite camp beside the freshwater spring near Kings Park on Mounts Bay Road, her grandfather witnessed the arrival of Lieutenant-Colonel Frederick Irwin, cousin of James Stirling (Bates, “Fanny”). In 1879, colonial entrepreneurs established the Swan Brewery at this significant locale (Welborn). Her grandmother’s gravesite later became Government House (Bates, “Fanny”) and she protested vociferously outside “the stone gates guarded by a sentry [that] enclosed her grandmother’s burial ground” (Bates, The Passing 70). Balbuk’s other grandmother was buried beneath Bishop’s Grove, the residence of the city’s first archibishop, now Terrace Hotel (Bates, “Aboriginal”). Historian Bob Reece observes that Balbuk was “the last full-descent woman of Kar’gatta (Karrakatta), the Bibbulmun name for the Mount Eliza [Kings Park] area of Perth” (134). According to accounts drawn from Bates, her home ground traversed the area between Heirisson Island and Perth’s north-western limits. In Kings Park, one of her relatives was buried near a large, hollow tree used by Nyoongar people like a cistern to capture water and which later became the site of the Queen Victoria Statue (Bates, “Aboriginal”). On the slopes of Mount Eliza, the highest point of Kings Park, at the western end of St Georges Terrace, she harvested plant foods, including zamia fruits (Macrozamia riedlei) (Bates, “Fanny”). Fanny Balbuk’s knowledge contributed to the native title claim lodged by Nyoongar people in 2006 as Bennell v. State of Western Australia—the first of its kind to acknowledge Aboriginal land rights in a capital city and part of the larger Single Nyoongar Claim (South West Aboriginal Land and Sea Council et al.). Perth’s colonial administration perceived the city’s wetlands as impediments to progress and as insalubrious environments to be eradicated through reclamation practices. For Balbuk and other Nyoongar people, however, wetlands were “nourishing terrains” (Rose) that afforded sustenance seasonally and meaning perpetually (O’Connor, Quartermaine, and Bodney). Mary Graham, a Kombu-merri elder from Queensland, articulates the connection between land and culture, “because land is sacred and must be looked after, the relation between people and land becomes the template for society and social relations. Therefore all meaning comes from land.” Traditional, embodied reliance on Perth’s wetlands is evident in Bates’ documentation. For instance, Boojoormeup was a “big swamp full of all kinds of food, now turned into Palmerston and Lake streets” (Bates, “Aboriginal”). Considering her cultural values, Balbuk’s determination to maintain pathways through the increasingly colonial Perth environment is unsurprising (Figure 2). From Heirisson Island: a straight track had led to the place where once she had gathered jilgies [crayfish] and vegetable food with the women, in the swamp where Perth railway station now stands. Through fences and over them, Balbuk took the straight track to the end. When a house was built in the way, she broke its fence-palings with her digging stick and charged up the steps and through the rooms. (Bates, The Passing 70) One obstacle was Hooper’s Fence, which Balbuk broke repeatedly on her trips to areas between Kings Park and the railway station (Bates, “Hooper’s”). Her tenacious commitment to walking ancestral routes signifies the friction between settlement infrastructure and traditional Nyoongar livelihood during an era of rapid change. Figure 2. Determination of Fanny Balbuk’s Journey between Yoonderup (Heirisson Island) and Lake Kingsford, traversing what is now the central business district of Perth on the Swan River (2014). Image background prepared by Dimitri Fotev. Track interpolation by Jeff Murray. Project Background and Approach Inspired by Fanny Balbuk’s story, Re-imagining Perth’s Lost Wetlands began as an Australian response to the Mannahatta Project. Founded in 1999, that project used spatial analysis techniques and mapping software to visualise New York’s urbanised Manhattan Island—or Mannahatta as it was called by indigenous people—in the early 1600s (Sanderson). Based on research into the island’s original biogeography and the ecological practices of Native Americans, Mannahatta enabled the public to “peel back” the city’s strata, revealing the original composition of the New York site. The layers of visuals included rich details about the island’s landforms, water systems, and vegetation. Mannahatta compelled Rod Giblett, a cultural researcher at Edith Cowan University, to develop an analogous model for visualising Perth circa 1829. The idea attracted support from the City of Perth, Landgate, and the University. Using stories, artefacts, and maps, the team—comprising a cartographer, designer, three-dimensional modelling expert, and historical researchers—set out to generate visualisations of the landscape at the time of British colonisation. Nyoongar elder Noel Nannup approved culturally sensitive material and contributed his perspective on Aboriginal content to include in the exhibition. The initiative’s context remains pressing. In many ways, Perth has become a template for development in the metropolitan area (Weller). While not unusual for a capital, the rate of transformation is perhaps unexpected in a city less than 200 years old (Forster). There also remains a persistent view of existing wetlands as obstructions to progress that, once removed, are soon forgotten (Urban Bushland Council). Digital visualisation can contribute to appreciating environments prior to colonisation but also to re-imagining possibilities for future human interactions with land, water, and space. Despite the rapid pace of change, many Perth area residents have memories of wetlands lost during their lifetimes (for example, Giblett, Forrestdale). However, as the clearing and drainage of the inner city occurred early in settlement, recollections of urban wetlands exist exclusively in historical records. In 1935, a local correspondent using the name “Sandgroper” reminisced about swamps, connecting them to Perth’s colonial heritage: But the Swamps were very real in fact, and in name in the [eighteen-] Nineties, and the Perth of my youth cannot be visualised without them. They were, of course, drying up apace, but they were swamps for all that, and they linked us directly with the earliest days of the Colony when our great-grandparents had founded this City of Perth on a sort of hog's-back, of which Hay-street was the ridge, and from which a succession of streamlets ran down its southern slope to the river, while land locked to the north of it lay a series of lakes which have long since been filled to and built over so that the only evidence that they have ever existed lies in the original street plans of Perth prepared by Roe and Hillman in the early eighteen-thirties. A salient consequence of the loss of ecological memory is the tendency to repeat the miscues of the past, especially the blatant disregard for natural and cultural heritage, as suburbanisation engulfs the area. While the swamps of inner Perth remain only in the names of streets, existing wetlands in the metropolitan area are still being threatened, as the Roe Highway (Roe 8) Campaign demonstrates. To re-imagine Perth’s lost landscape, we used several colonial survey maps to plot the location of the original lakes and swamps. At this time, a series of interconnecting waterbodies, known as the Perth Great Lakes, spread across the north of the city (Bekle and Gentilli). This phase required the earliest cartographic sources (Figure 3) because, by 1855, city maps no longer depicted wetlands. We synthesised contextual information, such as well depths, geological and botanical maps, settlers’ accounts, Nyoongar oral histories, and colonial-era artists’ impressions, to produce renderings of Perth. This diverse collection of primary and secondary materials served as the basis for creating new images of the city. Team member Jeff Murray interpolated Balbuk’s route using historical mappings and accounts, topographical data, court records, and cartographic common sense. He determined that Balbuk would have camped on the high ground of the southern part of Lake Kingsford rather than the more inundated northern part (Figure 2). Furthermore, she would have followed a reasonably direct course north of St Georges Terrace (contrary to David Whish-Wilson’s imaginings) because she was barred from Government House for protesting. This easier route would have also avoided the springs and gullies that appear on early maps of Perth. Figure 3. Townsite of Perth in Western Australia by Colonial Draftsman A. Hillman and John Septimus Roe (1838). This map of Perth depicts the wetlands that existed overlaid by the geomentric grid of the new city. Image Credit: State Library of Western Australia (Image Number: BA1961/14). Additionally, we produced an animated display based on aerial photographs to show the historical extent of change. Prompted by the build up to World War II, the earliest aerial photography of Perth dates from the late 1930s (Dixon 148–54). As “Sandgroper” noted, by this time, most of the urban wetlands had been drained or substantially modified. The animation revealed considerable alterations to the formerly swampy Swan River shoreline. Most prominent was the transformation of the Matagarup shallows across the Swan River, originally consisting of small islands. Now traversed by a causeway, this area was transformed into a single island, Heirisson—the general site of Balbuk’s birth. The animation and accompanying materials (maps, images, and writings) enabled viewers to apprehend the changes in real time and to imagine what the city was once like. Re-imagining Perth’s Urban Heart The physical environment of inner Perth includes virtually no trace of its wetland origins. Consequently, we considered whether a representation of Perth, as it existed previously, could enhance public understanding of natural heritage and thereby increase its value. For this reason, interpretive materials were exhibited centrally at Perth Town Hall. Built partly by convicts between 1867 and 1870, the venue is close to the site of the 1829 Foundation of Perth, depicted in George Pitt Morrison’s painting. Balbuk’s grandfather “camped somewhere in the city of Perth, not far from the Town Hall” (Bates, “Fanny”). The building lies one block from the site of the railway station on the site of Lake Kingsford, the subsistence grounds of Balbuk and her forebears: The old swamp which is now the Perth railway yards had been a favourite jilgi ground; a spring near the Town Hall had been a camping place of Maiago […] and others of her fathers' folk; and all around and about city and suburbs she had gathered roots and fished for crayfish in the days gone by. (Bates, “Derelicts” 55) Beginning in 1848, the draining of Lake Kingsford reached completion during the construction of the Town Hall. While the swamps of the city were not appreciated by many residents, some organisations, such as the Perth Town Trust, vigorously opposed the reclamation of the lake, alluding to its hydrological role: That, the soil being sand, it is not to be supposed that Lake Kingsford has in itself any material effect on the wells of Perth; but that, from this same reason of the sandy soil, it would be impossible to keep the lake dry without, by so doing, withdrawing the water from at least the adjacent parts of the townsite to the same depth. (Independent Journal of Politics and News 3) At the time of our exhibition, the Lake Kingsford site was again being reworked to sink the railway line and build Yagan Square, a public space named after a colonial-era Nyoongar leader. The project required specialised construction techniques due to the high water table—the remnants of the lake. People travelling to the exhibition by train in October 2014 could have seen the lake reasserting itself in partly-filled depressions, flush with winter rain (Figure 4).Figure 4. Rise of the Repressed (2014). Water Rising in the former site of Lake Kingsford/Irwin during construction, corner of Roe and Fitzgerald Streets, Northbridge, WA. Image Credit: Nandi Chinna (2014). The exhibition was situated in the Town Hall’s enclosed undercroft designed for markets and more recently for shops. While some visited after peering curiously through the glass walls of the undercroft, others hailed from local and state government organisations. Guest comments applauded the alternative view of Perth we presented. The content invited the public to re-imagine Perth as a city of wetlands that were both environmentally and culturally important. A display panel described how the city’s infrastructure presented a hindrance for Balbuk as she attempted to negotiate the once-familiar route between Yoonderup and Lake Kingsford (Figure 2). Perth’s growth “restricted Balbuk’s wanderings; towns, trains, and farms came through her ‘line of march’; old landmarks were thus swept away, and year after year saw her less confident of the locality of one-time familiar spots” (Bates, “Fanny”). Conserving Wetlands: From Re-Claiming to Re-Valuing? Imagination, for philosopher Roger Scruton, involves “thinking of, and attending to, a present object (by thinking of it, or perceiving it, in terms of something absent)” (155). According to Scruton, the feelings aroused through imagination can prompt creative, transformative experiences. While environmental conservation tends to rely on data-driven empirical approaches, it appeals to imagination less commonly. We have found, however, that attending to the present object (the city) in terms of something absent (its wetlands) through evocative visual material can complement traditional conservation agendas focused on habitats and species. The actual extent of wetlands loss in the Swan Coastal Plain—the flat and sandy region extending from Jurien Bay south to Cape Naturaliste, including Perth—is contested. However, estimates suggest that 80 per cent of wetlands have been lost, with remaining habitats threatened by climate change, suburban development, agriculture, and industry (Department of Environment and Conservation). As with the swamps and lakes of the inner city, many regional wetlands were cleared, drained, or filled before they could be properly documented. Additionally, the seasonal fluctuations of swampy places have never been easily translatable to two-dimensional records. As Giblett notes, the creation of cartographic representations and the assignment of English names were attempts to fix the dynamic boundaries of wetlands, at least in the minds of settlers and administrators (Postmodern 72–73). Moreover, European colonists found the Western Australian landscape, including its wetlands, generally discomfiting. In a letter from 1833, metaphors failed George Fletcher Moore, the effusive colonial commentator, “I cannot compare these swamps to any marshes with which you are familiar” (220). The intermediate nature of wetlands—as neither land nor lake—is perhaps one reason for their cultural marginalisation (Giblett, Postmodern 39). The conviction that unsanitary, miasmic wetlands should be converted to more useful purposes largely prevailed (Giblett, Black 105–22). Felicity Morel-EdnieBrown’s research into land ownership records in colonial Perth demonstrated that town lots on swampland were often preferred. By layering records using geographic information systems (GIS), she revealed modifications to town plans to accommodate swampland frontages. The decline of wetlands in the region appears to have been driven initially by their exploitation for water and later for fertile soil. Northern market gardens supplied the needs of the early city. It is likely that the depletion of Nyoongar bush foods predated the flourishing of these gardens (Carter and Nutter). Engaging with the history of Perth’s swamps raises questions about the appreciation of wetlands today. In an era where numerous conservation strategies and alternatives have been developed (for example, Bobbink et al. 93–220), the exploitation of wetlands in service to population growth persists. On Perth’s north side, wetlands have long been subdued by controlling their water levels and landscaping their boundaries, as the suburban examples of Lake Monger and Hyde Park (formerly Third Swamp Reserve) reveal. Largely unmodified wetlands, such as Forrestdale Lake, exist south of Perth, but they too are in danger (Giblett, Black Swan). The Beeliar Wetlands near the suburb of Bibra Lake comprise an interconnected series of lakes and swamps that are vulnerable to a highway extension project first proposed in the 1950s. Just as the Perth Town Trust debated Lake Kingsford’s draining, local councils and the public are fiercely contesting the construction of the Roe Highway, which will bisect Beeliar Wetlands, destroying Roe Swamp (Chinna). The conservation value of wetlands still struggles to compete with traffic planning underpinned by a modernist ideology that associates cars and freeways with progress (Gregory). Outside of archives, the debate about Lake Kingsford is almost entirely forgotten and its physical presence has been erased. Despite the magnitude of loss, re-imagining the city’s swamplands, in the way that we have, calls attention to past indiscretions while invigorating future possibilities. We hope that the re-imagining of Perth’s wetlands stimulates public respect for ancestral tracks and songlines like Balbuk’s. Despite the accretions of settler history and colonial discourse, songlines endure as a fundamental cultural heritage. Nyoongar elder Noel Nannup states, “as people, if we can get out there on our songlines, even though there may be farms or roads overlaying them, fences, whatever it is that might impede us from travelling directly upon them, if we can get close proximity, we can still keep our culture alive. That is why it is so important for us to have our songlines.” Just as Fanny Balbuk plied her songlines between Yoonderup and Lake Kingsford, the traditional custodians of Beeliar and other wetlands around Perth walk the landscape as an act of resistance and solidarity, keeping the stories of place alive. Acknowledgments The authors wish to acknowledge Rod Giblett (ECU), Nandi Chinna (ECU), Susanna Iuliano (ECU), Jeff Murray (Kareff Consulting), Dimitri Fotev (City of Perth), and Brendan McAtee (Landgate) for their contributions to this project. The authors also acknowledge the traditional custodians of the lands upon which this paper was researched and written. 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Karies gigi adalah penyakit jaringan gigi yang ditandai dengan kerusakan jaringan, dimulai dari permukaan gigi meluas ke arah pulpa. Karies gigi dapat terjadi pada setiap orang yang dapat timbul pada suatu permukaan gigi dan dapat meluas kebagian yang lebih dalam dari gigi. Masalah utama dalam rongga mulut anak sampai saat ini yaitu penyakit karies gigi, sehingga masalah kesehatan gigi dan mulut menjadi perhatian yang sangat penting dalam pembangunan kesehatan yang salah satunya disebabkan oleh rentannya kelompok anak usia sekolah dari gangguan kesehatan gigi. Tujuan penelitian ini untuk mengetahui gambaran status karies anak sekolah dasar di kelurahan Kinilow 1 kecamatan Tomohon Utara. Penelitian ini menggunakan metode deskriptif dengan desain potong lintang (cross-sectional) dan dilakukan di 2 SD yaitu SD GMIM Kinilow dan SD Katolik Kinilow. Jumlah sampel 73 orang yang diperoleh dengan menggunakan metode total sampling. Hasil penelitian menunjukkan indeks DMF-T rata-rata untuk 73 responden ini yaitu 3,5 yang berdasarkan kriteria WHO berada pada kategori sedang. Rata-rata indeks DMF-T pada anak laki-laki yaitu 3,4 sedangkan anak perempuan 3,6. Indeks DMF-T rata-rata anak dengan pendidikan terakhir orang tua pada tingkat SD sebesar 3, SMP sebesar 3,3, SMA sebesar 3,6, D3 sebesar 4 dan S1 sebesar 3,5, yang seluruhnya berada pada kategori status karies sedang.Kata kunci : Status karies, anak SD, indeks DMF-TABSTRACTDental cariesis a dental tissue diseasethat marked bytissue destruction, startingfromthe surface of thetoothextendsto thepulp. Dental cariescanoccuron anypersonthatmayariseonatoothsurfaceandmay extend intothe deeper partof thetooth. The mainproblemsin theoral cavity childrenuntil this timeisdentalcariesdisease, so thatoral healthissuesbe an important concernin thedevelopmentof health which one of them causedby thevulnerability children school ageofdentalhealth problems. This study aims to determine the description ofcariesstatus inprimary school children in Kinilow 1 of NorthTomohon. The research usesdescriptive method with cross-sectionaldesignandconductedfor two schools, that isSDGMIMKinilow and SDKatolikKinilow. Number ofsamples73wereobtainedby using totalsampling method. The results showedDMF-T indexaverage forthe73respondentswas3.5which based onthe WHOcriteria isfair category. The DMF-T index average of male students is 3,4and female students is 3,6. DMF-T indexaverage childrenwiththehighest educationlevelof parents in SD is 3, SMP is 3,3, SMA is 3,6, D3 is 4 and S1 is 3,5, which entirelyare in thecategory offaircariesstatus.Keywords: Caries status, elementary school children, DMF-T index