Oak Ridges Moraine Area Research Articles

Flood characteristic description using the singularity method

An advanced understanding of the flood mechanism will provide scientific evidence for decision makers for assessing water resources and development planning. Mathematical models can be used to develop new indices for flood characteristics description and forecasting. In this study, a singularity index (fractal model) was developed by using peak flow and flow discharge data with time to describe flooding events in the Oak Ridges Moraine (ORM) area, especially for characterizing flow change properties. It was found that the singularity index can be used to describe flood characteristics, which describes the changing behaviour around the peak of the flood flow. The higher the singularity index, the more quickly the flood process changes, and vice versa. It was also observed that the singularity index is higher when more watersheds have urban land cover, and it is lower when fewer watersheds have urban land cover and more have agricultural land cover.

Converging ice streams: an unreasonable hypothesis for deposition of the Oak Ridges Moraine, southern Ontario

The hypothesis that Oak Ridges Moraine (ORM) formed between converging ice streams requires critical testing. Available data (e.g., digital elevation models, maps, seismic profiles, continuous cores, and pit exposures) are inconsistent with the converging ice stream hypothesis. Combined analysis of landform and subsurface data permits testing the ORM area stratigraphic sequence and sedimentary origin. Stratigraphic data indicate that drumlinized Newmarket Till, incised by north–south-oriented (tunnel) valleys, extends beneath ORM. Thus, streamlining on Newmarket Till is older than ORM and has no direct bearing on its formation. The north–south-trending valleys truncate streamlined Newmarket Till, extend to bedrock, have inset eskers, and occur beneath ORM. Hence, these valleys are older than ORM and have a subglacial rather than a proglacial origin. Overlying the mega-scale lineations and incised channels are topographically elevated (>300 m a.s.l.), ORM glaciofluvial–glaciolacustrine sequences. Its east to west paleoflow trend indicates an east–west-oriented hydraulic gradient, orthogonal to expected gradients of proposed north-south converging ice streams. The exclusive presence of ORM meltwater sediments, with rare deformation, is incompatible with a converging ice stream, deforming-bed hypothesis. Halton sediment grades upward from stratified sand (ORM) to interbedded diamicton and glaciolacustrine sediment, rather than deformation till. Halton sediment overlies ORM and consequently the proposed Halton ice streaming is younger than the moraine. Halton Till is present in few of the predicted ice stream areas, and where Halton Till is present, it has no mega-scale lineations. In sum, the weight of evidence unequivocally argues against a converging ice-stream process model for the ORM.

The Development of Web-based Spatial Decision Support Services for Flood Forecasting

This paper examines current challenges for real time flood forecasting and develops a prototype Web-based Spatial Decision Support Services (WSDSS) for flood forecasting in the Oak Ridges Moraine (ORM) area, southern Ontario, Canada. This system integrates models, analytical tools, databases, graphical user interfaces, and spatial decision support services to help the public and decision makers to easily access flood and flood-threatened information. The development of Graphical User Interface (GUI), database, model base, spatial and graphic data display system and decision making support services are introduced.

A revised depositional setting for Halton sediments in the Oak Ridges Moraine area, Ontario

Outcrop and continuous core descriptions, high-resolution seismic profiling, and downhole geophysical data are integrated with detailed mapping to update sedimentary and stratigraphic frameworks for Halton sediment, a complex mud-rich lithofacies succession. Halton sediment has a gradational transition from underlying Oak Ridges Moraine (ORM) sediment and can abruptly overlie Newmarket Till. Halton strata thin and fine upwards from ORM sand and gravel to graded sand, silt, and clay rhythmites, with muddy diamicton and sand and gravel interbeds. These strata fill basin lows and drape ORM sediment lobes and Newmarket Till drumlins. These distinct sedimentary units are here informally referred to as Halton formation. Formal Halton Till is a proposed subunit of Halton formation, a clay-rich diamicton mapped from Niagara Peninsula to ORM and eastward. Halton Till has traditionally been inferred to represent a late, climatically induced readvance of grounded ice from Lake Ontario basin, which deposited drumlinized till. Halton sedimentary architecture and facies are interpreted as deposition in an ice-marginal or subglacial lake bounded by Niagara Escarpment, ORM, and grounding line oscillation of a semi-buoyant ice shelf or ice lid over Lake Ontario. Large volumes of transported mud are distal equivalents of ORM high-energy gravelly sand deposits to the east. Glaciolacustrine sedimentation is indicated by mud-rich texture and laminations. Clay–silt rhythmites, diamicton interbeds, and intraclasts indicate ponding, debris flow, and periodic ice loading. Halton depositional model may apply to other muddy diamictons in Great Lakes basins. Halton formation facies are not compatible with proposed grounded ice stream events in Lake Ontario basin.

Characterization of peak flow events with local singularity method

Abstract. Three methods, return period, power-law frequency plot (concentration-area) and local singularity index, are introduced in the paper for characterizing peak flow events from river flow data for the past 100 years from 1900 to 2000 recorded at 25 selected gauging stations on rivers in the Oak Ridges Moraine (ORM) area, Canada. First a traditional method, return period, was applied to the maximum annual river flow data. Whereas the Pearson III distribution generally fits the values, a power-law frequency plot (C-A) on the basis of self-similarity principle provides an effective mean for distinguishing "extremely" large flow events from the regular flow events. While the latter show a power-law distribution, about 10 large flow events manifest departure from the power-law distribution and these flow events can be classified into a separate group most of which are related to flood events. It is shown that the relation between the average water releases over a time period after flow peak and the time duration may follow a power-law distribution. The exponent of the power-law or singularity index estimated from this power-law relation may be used to characterize non-linearity of peak flow recessions. Viewing large peak flow events or floods as singular processes can anticipate the application of power-law models not only for characterizing the frequency distribution of peak flow events, for example, power-law relation between the number and size of floods, but also for describing local singularity of processes such as power-law relation between the amount of water released versus releasing time. With the introduction and validation of singularity of peak flow events, alternative power-law models can be used to depict the recession property as well as other types of non-linear properties.

A combined power-law and exponential model for streamflow recessions

Summary This paper proposes a non-linear model to describe streamflow recessions. A model of combining power-law and exponential functions is derived from a non-linear differential equation associating outflow change rate and flow itself with a time-dependent decreasing decay rate. The decay rate is approximated by the first three terms in a Taylor series expansion. The solution of the resulting differential equation includes three components of the expansion determining two exponential functions and a power-law function, respectively. It is demonstrated analytically and empirically that the introduction of a non-linear differential equation comprising a mixture of power-law and exponential forms is superior to using an ordinary differential equation with exponential solution, or a non-linear equation with power-law solution, for modeling the decay patterns of flow in river systems. Analytical properties of the mixing model are discussed and the model is subsequently validated by characterizing the relationships between decay of peak flow as a function of time after the initial occurrence of flow peak in 10 datasets of flow events chosen from five gauging stations in the Oak Ridges Moraine (ORM) area, Canada.

A 3-dimensional geological model of the Oak Ridges Moraine area, Ontario, Canada

Please click here to download the map associated with this article. The Oak Ridges Moraine area, southern Ontario, includes most of the Greater Toronto Area, which is the most populated region of Canada. The ∼ 11,000 km2 region is bounded to the south by Lake Ontario and to the north where Paleozoic bedrock abuts Precambrian Canadian Shield. The area extends 160 km eastward from the Niagara Escarpment, a prominent 100 m high regional bedrock scarp. The surficial sediment is up to 200 m thick, and reveals exposures of the oldest Quaternary sediment in southern Canada. Population growth has caused land use conflicts and increased pressure on groundwater resources. Construction of a regional 3-D geological model of the glacial stratigraphy was needed to support a better understanding of aquifer distribution, scale, and resource potential and protection. Mapping of the regional glacial geomorphology and sediment succession identified a number of distinct landforms: tunnel channels, drumlins, eskers, moraines, and till and lacustrine plains. Using sequence stratigraphic concepts, strata have been grouped into four principal units that unconformably overlie Paleozoic bedrock: Lower sediment, Newmarket Till, Oak Ridges Moraine, and Halton Till. These four Quaternary units plus bedrock have been mapped in the subsurface as a succession of interpolated surfaces using an innovative stratigraphic database-GIS approach. The model-building process involved stratigraphically coding high-quality data, then integrating an extensive and diverse array of subsurface geological and archival datasets using an expert system (geological rules). Stratigraphic data subsets were then extracted and merged with DEM-controlled surface mapping and interpolated in a GIS.

GIS modeling for predicting river runoff volume in ungauged drainages in the Greater Toronto Area, Canada

This paper introduces two parsimonious models for predicting runoff for ungauged basins from the observed river flow data in gauged basins and precipitation data from rain gauging stations in the same area. The models assume the runoff is related to the precipitation subject to variance of drainage basins. The runoff can be modeled as a function of precipitation and parameters determined by basin descriptive properties. The parameter values of the models can be calibrated statistically on the basis of observed historical runoff data and precipitation data. Further the parameters can be regressed to associate with the areas of different landcover types occupying the drainage basins. This regression model can be used for estimating parameter values for ungauged basins in the same study area which can be further used together with precipitation data to predict the runoff in the ungauged basins. An example of adopted Soil Conservation Service (SCS) method with application to the Oak Ridges Moraine area was introduced to demonstrate the implementation of the models introduced. The information used for the modeling and prediction includes: surficial geology, DEM, Landsat TM images, historical river flow data, and precipitation and temperature data from weather stations.

Application of Weights of Evidence Method for Assessment of Flowing Wells in the Greater Toronto Area, Canada

Flowing wells extracted from the Ministry of Ontario Environment and Energy (MOEE) water well data set from the Oak Ridges Moraine (ORM) area, Ontario, Canada, were treated as training point set to evaluate the potential distribution of artesian aquifers and their spatial associations with other geological and topological features in the study area. Evidential layers of geological and topographical features were constructed on the basis of the digital elevation model (DEM) and a geological map using GIS buffering functions in conjunction with weights of evidence method. It has been demonstrated that the locations of the flowing wells in the Oak Ridges Moraine area are associated spatially with the distances, (a) 500–5000 m from the oak ridges moraine deposits, (b) 500–4000 m from thick drift layer delineated on the drift thickness map created from water well data, and (c) 1500–2500 m from steep slope zones with slope above 8 degree calculated from a DEM. Applying a combination of these conditions can reduce the predicting target areas of having flowing wells by two thirds. Outcomes of this research are important both because the impact of the results on understanding of characteristics of aquifers and their relationships with other geological and topographical features and because it generates a probability map showing the potential location of artesian aquifers in the ORM area. In addition, the methodologies used in the paper will be applicable for modeling the distributions of other types of objects such as surface water bodies and low flow of streams in a watershed context in the study area.

GIS spatial modeling of river flow and precipitation in the Oak Ridges Moraine area, Ontario

The spatial pattern of storm runoff volume is of interest in many environmental concerns and storm runoff is an important component in the hydrologic cycle because of its relationship to issues such as flooding and water quality. The isolation of the groundwater component allows the net effect of meteorology to stream flow rate. Hence, the time lag for the stream in respond to the precipitation event depends mainly on the physical and hydrological characteristics of the drainage basins such as land use, topography and geometry of the drainage basins. This paper uses different types of statistical and GIS techniques in an attempt to relate the meteorological data to the hydrological data, showing the spatial pattern of different respond time for different watersheds in Oak Ridges Moraine Area in the southern part of Ontario, Canada. The results were then related to the different physical properties of the watersheds delineated by GIS software.

GIS spatial modeling of river flow and precipitation in the Oak Ridges Moraine area, Ontario

The spatial pattern of storm runoff volume is of interest in many environmental concerns and storm runoff is an important component in the hydrologic cycle because of its relationship to issues such as flooding and water quality. The isolation of the groundwater component allows the net effect of meteorology to stream flow rate. Hence, the time lag for the stream in respond to the precipitation event depends mainly on the physical and hydrological characteristics of the drainage basins such as land use, topography and geometry of the drainage basins. This paper uses different types of statistical and GIS techniques in an attempt to relate the meteorological data to the hydrological data, showing the spatial pattern of different respond time for different watersheds in Oak Ridges Moraine Area in the southern part of Ontario, Canada. The results were then related to the different physical properties of the watersheds delineated by GIS software.

Regional unconformities and the sedimentary architecture of the Oak Ridges Moraine area, southern Ontario

Seismic stratigraphy, geometry, and sediment facies within the Oak Ridges Moraine (ORM) area of Ontario record major structural elements and surfaces of the Quaternary sedimentary sequence. The derived stratigraphic architecture can be used to identify the key elements of a regional erosional surface, represented by an unconformity in the subsurface, and associated overlying channel sediments. The erosional surface – unconformity forms a distinct time datum in the Quaternary sequence, which provides an important aid to lithostratigraphic correlation. The architecture also gives improved understanding of the effects of erosion on the late-glacial landscape. The surfaces of erosional drumlins and intervening troughs, and the beds and banks of meltwater channels in the ORM area, define the regional unconformity, highlighted by seismic profiles linked to continuously cored boreholes. These features are attributed to regional-scale, subglacial meltwater flow events. The sculpted surfaces, which are analogous to water-eroded forms, the presence of boulder lags and coarse-grained deposits on the regional erosional surface, and the channels with undulating profiles provide the vital supporting evidence for a meltwater interpretation. The inter-regional extent of the unconformity is inferred from the coherence of regional paleoflows and the extent of drumlinized uplands, tunnel channels, and scoured bedrock terrain across ~75% of the landscape from the ORM area east and south to the Finger Lakes, New York. The implied magnitude of erosion suggests a pressing need for directed sedimentological study in those ocean basins that were probable depositional sites for flood deposits.

GIS-based statistical and fractal/multifractal analysis of surface stream patterns in the Oak Ridges Moraine

Conventional quantities (stream length, number of streams, bifurcation ratio, density of streams per unit drainage area, elevation difference, slope, and perimeter and area of drainage basins) were extracted for approximately 322 drainage basins from a DEM of the Oak Ridges Moraine area, southern Ontario. These values were mapped and analyzed using statistical and multifractal approaches and GIS to characterize the stream networks and drainage basin systems. Useful measures for characterizing drainage basins in the area included, slope, stream densities, ratio of perimeter and area, and ratio of stream lengths. The distinct patterns identified on the basis of these parameters and on the combined indexes generated by using multivariate statistical analysis were compared with other datasets (geology, bedrock topography, and drift thickness). The associations illustrate the relationship between stream patterns and geological and geomorphological factors. The stream networks in the area as a whole have statistical space-filling properties or are free of geological constraints; however, the variance of individual drainage basins can be characterized by a combined principal component consisting of several quantities. Geological and hydrological interpretations suggest that geological structures, bedrock topography, drift thickness, lithology and slope of drainage basins are the main geological and geomorphological factors influencing the evolution of streams in the area. The results obtained on the basis of stream and drainage basin analysis may provide information for an improved understanding of hydrological characteristics in the area. As an example, the drainage basins along the Niagara Escarpment and on the south side of the Oak Ridges Moraine show distinct patterns with relatively high stream densities and steeper slopes, which may be one of the reasons why these basins have relatively high baseflow compared to basins elsewhere. In addition, high baseflow may have partly induced a relatively high stream density.

Seismic facies and regional architecture of the Oak Ridges Moraine area, southern Ontario

Analysis of over 50 line-kilometres of land-based, shallow, seismic reflection profiles has provided a means of investigating the subsurface architecture and stratigraphic relationships of the glacial deposits in and beneath the Oak Ridges Moraine (ORM). The focus of this paper is the role of seismic reflection surveys, and the derived seismic facies and facies geometry, in the development of a well-constrained, regional, conceptual model of the subsurface stratigraphy in the area and the improved inferences these data allow regarding glacial event sequence and process interpretations. The data define four major seismic facies that characterize the complex glacial sequence of the ORM area. High-reflectivity facies (I) can be traced regionally and related to an eroded Newmarket Till surface. Medium (II) and low (III) reflectivity facies are generally associated with coarse-grained glaciofluvial deposits and laterally extensive, glaciolacustrine sequences of sand, silt, and clay, respectively. A chaotic facies (IV) is common within buried channels, and attributed to instability and (or) rapid channel-fill deposition. Seismic geometry (with borehole verification) shows that a broad surface network of channels extends below thick ORM sediments. The channel system is part of a regional unconformity formed on the Newmarket Till (facies I). The buried channels can have steep sides, and their fills frequently include tabular sheets, eskers, and (or) large cross-beds. The observations are consistent with the scenario of sheet flow and channel cutting by high-energy subglacial meltwater and filling with gravel, sand, and silt in succession (facies II and III) as the flows waned.

Seismic facies and regional architecture of the Oak Ridges Moraine area, southern Ontario

Seismic facies and regional architecture of the Oak Ridges Moraine area, southern Ontario