2.3 Water Budget Data In Ontario

Transcription

1 2.3 Water Budget Data In Ontario Water budget data available for Ontario includes meteorologic data, hydrometric data and groundwater data. Geological and physiographical data provide information to describe the structure of the watershed Meteorological Data In order to calculate moisture flux and account for the transfer of moisture through the system, the following meteorological data are required: temperature (mean, daily minimum and maximum, or even hourly depending on the study requirements); wind speed and direction; radiation; vapour-pressure; heat exchange rate; precipitation, including rainfall and snowfall (annual, monthly, weekly, daily or hourly intervals); and evaporation. Meteorological data from over one thousand stations in Ontario can be obtained from the Climatology Division, Atmospheric Environment Service, Environment Canada. In the past few years, extensive analyses have been undertaken to update various data sets, which are useful in regional water budget analysis (CCL, 1999). The data are available in digital and hard copy formats and include: mean annual precipitation map, Ontario; mean monthly precipitation map, Ontario; mean annual and monthly snowfall; mean annual runoff map for Ontario; mean annual and monthly evaporation/evapotranspiration; locations of meteorological stations; locations of hydrometric stations; 1:2 year seven day low flow (7 Q 2 ) isolines and grid files; 1:20 year peak flow isolines and grid files; Water Budget Analysis on a Watershed Basis 2-28

2 1:100 year peak flow isolines and grid files; and the base flow index (BFI) isolines and grid files. The design rainfall intensity-duration-frequency isoline and grid files for 1:2, 1:5, 1:10, 1:20, 1:50 and 1:100 year return periods and 5 minute, 10 minute, 30 minute, 1 hour, 3 hour, 6 hour, 12-hour and 24-hour durations are also available Hydrometric and Physical Data Available hydrometric data includes the following list of information: Hydrological Data: - stream flow; - water level; - historical groundwater table; - soil water moisture content; - sediment concentration; and - snow surveys. Watershed physical parameters include the following: - watershed area; - land use information - channel and valley slope; - vegetation cover (type of covers and their distributions); - soil types and distributions; - soil particle size distribution; - soil porosity ratio; - soil moisture field capacity; - soil moisture wilting point; - soil infiltration rate; and - soil hydraulic conductivity. The hydrological data is available at Inland Waters Directorate, Water Resources Branch, Water Survey of Canada. A CD-ROM which contains the hydrometric data for all stations across Canada is released annually, which summarizes all gauged streamflow and sediment concentration measurements in Ontario. Water Budget Analysis on a Watershed Basis 2-29

3 The physical parameters are typically derived from available topographic mapping, previous reports, and field surveys of the watershed. The accurate determination of watershed boundaries is an important component of water budget analysis. It should also be noted that surface and groundwater boundaries may not coincide. Topographic mapping at a scale appropriate to the problem at hand should be utilized. The Ministry of Natural Resources can also provide watershed boundaries and locations of agricultural tile drains (Kenney, MNR Geomatic Services, 1995) based on GIS analysis. Digital elevation model data (DEM) is also available from the Ministry of Natural Resources (MNR, 1994, 1996) Groundwater Data Groundwater data is essential to water budget analysis; various available data are discussed in the following sections: Geology Basic information describing Ontario s geology can be found in several studies (e.g. Howard et al, 1993) and from geological maps of Ontario (Chapman and Putnam, 1966; MNR, Ontario Geological Referencing Grid, 1985; Barnett et al, 1991; Gupta, 1991; Sharpe and Finley, 1997; Sharpe et al, 1997). Availability of the most current geological information is generally contained in borehole data and can be ascertained by contacting: ORC (Ontario Realty Corporation); OGS (Ontario Geological Survey); GSC (Geological Survey of Canada); CA's (Conservation Authorities); MOE (Ministry of Environment); GAC (Geological Association of Canada); and (OPC) Ontario Power Corporation. There are several known groundwater resource regions in Ontario (see Figures 2.8a and 2.8b). Studies in some areas have also identified groundwater probability in Ontario (MOE, 1981). Water Budget Analysis on a Watershed Basis 2-30

4 Groundwater Compilations General information on water level data can be found in the Ontario Ministry of the Environment Water Well Records database and provincial groundwater monitoring networks. Other information on hydraulic head and groundwater flow paths have been identified by MOE (Smart, 1994; Hunter, 1996; Sibul et al, 1977; Boyce et al, 1997). Several area-wide water resources assessment studies carried out in Ontario collected site-specific data using well and borehole installations, including piezometric nests. Typical is the work of Russell et al, 1997, who used piezometric nest data in a kettle lake area to determine vertical hydraulic gradient and recharge associated with these lakes. Researchers at the University of Toronto (Elyes and Howard, 1988; Gerber and Howard, 1992, 1997) and the Waterloo Centre for Groundwater Research have also described techniques for collection of data. These include sampling techniques for analyzing the movements of groundwater contaminants. Monitoring guidelines and protocols for well construction, and data collection, are also available which describe procedures to obtain consistent data sets (MOE, 1995). Table 2.7 Internet Sources of Data MOE: GAC: OGS: /MNDM/MINES/OGS/ MMDOGSE.htm Oak Ridges Moraine: /page1/envir/orm/orm.htm Selected data sets can also be obtained through the Internet (e.g. see Table 2.7) Groundwater Mapping The Ministry of the Environment has mapped groundwater availability on a regional scale by addressing: probability water quantity available; depth at which water is commonly found; water quality at sampled locations; scaling and mapping; and supplies in shallow overburden. Water Budget Analysis on a Watershed Basis 2-31

5 These data collections and analysis approaches have been viewed from a watershed management perspective (Sibul et al, 1977; Howard, 1981; MOE, 1981, 1988; Hill, 1982; Sanderson, 1991; Holysh, 1998; Beatty, 1998). The following general information has been developed to characterize the overall groundwater resources in Ontario: water resources reports (e.g. Sibul, 1980); water resources bulletins (e.g. MOE Publication No. 2-30, 1979); groundwater probability map series (e.g. MOE Publication 1969, 1970, 1971, 1974, 1979, 1981, 1984, 1986); and major aquifers in Ontario map series (e.g. MOE Publication 1970, 1971, (No. 1), 1978 (No. 1-6)). The Ministry of Environment previously developed (data up to 1984) an inventory of observation wells in Ontario. The information provided is summarized as follows: Type I wells that show natural background fluctuations in water levels, classified as index wells ; Type II wells essential for assessing and preventing water shortage problems caused by excessive withdrawals; and Type III wells which are related to groundwater resources inventory and special interest studies, such as water-level interference complaint problems. Multi-purpose wells also provide several functions that may include those within the Type I, II or III categories. The availability of observation well information for specific watersheds can be determined by examining observation well map sheets that show the areas of interest (MOE, 1980). The locations are provided on the national topographic series map, scale 1:250,000. Water Budget Analysis on a Watershed Basis 2-32

6 Although no longer published, older traditional well data has been provided in MOE s Publication Data for Observation Wells in Ontario. This information should be field checked for errors since existing data has proven to be difficult to use for subwatershed studies. A recent investigation (CCIW, Pigott 1998) has summarized water well construction records in Ontario using GIS techniques: 85,000 records covering 27,600 km 2 ; period 1908 to 1992 (most records during ); temporal and depth resolution is limited; and adequate spatial information for regional studies. Water Budget Analysis on a Watershed Basis 2-33