The Distribution and Morphometry of Lakes and Reservoirs in British Columbia: A Provincial Inventory

Article excerpt

Introduction

Lakes play an important role as a critical ecosystem component for many aquatic and terrestrial plant and animal species and are an invaluable freshwater resource for human populations. To improve the regional knowledge base of British Columbia's water resources, a comprehensive inventory and assessment of the distribution and morphometry of lakes and reservoirs has been developed using the most recently available provincial mapping and the large-scale spatial-analysis capabilities of Geographic Information Systems (GIS). The abundance of lake bodies and their extensive distribution across the physiographically diverse and largely remote landmass of British Columbia have hindered previous attempts to carry out such an analysis (Northcote and Larkin 1956; Northcote 1964; Trainor and Church 1996). Furthermore, there exists a continuum of lakes and other surface-water features, including ponds (scale continuum), wetlands (maturity continuum) and rivers (flow dynamics continuum), that makes classification difficult. Although British Columbia has fewer lakes than the other western Canadian provinces (Northcote and Larkin 1963), it probably contains the greatest diversity of lake types because of the complex tectonic and glacial history of the Canadian cordillera. The largest water bodies and major physiographic elements of the province (based on Mathews 1986) are shown in Figure 1.

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From a regional perspective, a provincial lake inventory would enhance our potential understanding of the physical, chemical and biological nature of the lakes of British Columbia. Such an inventory and classification of our physical landscape features will be necessary for the management and protection of provincial freshwater resources and aquatic ecosystems. The inventory may also be useful in characterising regional geomorphology and hydrology of the province and will serve as an example of how large digital databases and GIS capabilities may be utilised in cataloguing and interpreting landscapes in a spatial context.

Previous Work

Northcote and Larkin (1956) used lake surveys compiled by the British Columbia Game Commission (100 lakes) to investigate relations between the physical and chemical characteristics of the lakes and standing crops of organisms. Total dissolved content of lake water was concluded to be the most important factor in determining standing crops in lakes of British Columbia. Based primarily on productivity, nine limnologic regions were proposed for the province. Northcote (1964) provided additional information on these regions, briefly described several new regions and made the first attempt to enumerate the number of lakes in British Columbia for the purpose of sport-fish management. Using the limited government resource mapping available at that time, it was estimated that there were over 20,000 lakes in the province. Northcote and Larkin (1963) provide a review of early limnologic endeavours and limnologic research carried out in British Columbia.

Based on eighty years of lake surveying, the Ministry of Sustainable Resource Management (2003), Aquatic Information Branch, has compiled and curates a provincial fisheries lake survey that contains basic morphometric data (including lake volume) for approximately 3,000 lakes. Using a subset of this inventory in conjunction with the Lake Classification Project Database (collected by the Canada Department of Fisberies and Oceans--1,000 lakes in total), Trainor and Church (1996) carried out a morphometric assessment and characterisation for three provincial subregions. Principal findings of the study included the identification of a clear planimetric relation between lake perimeter and area and a regionally variable hypsometric relation between lake volume and depth versus area. All relations exhibited substantial residual scatter. Variates of ecological interest, including lake littoral area and flushing time, were also investigated. …