| Multiply | By | To obtain |
|---|---|---|
| Cubic foot (ft3) | 0.02832 | cubic meter |
| Feet (ft) | 0.3048 | meters |
| Inches (in.) | 25.4 | millimeters |
| Gallon (gal.) | 3.785 | liter |
| Miles (mi) | 1.609 | kilometers |
| Temperature in degrees Celsius (°C) can be converted to degrees Fahrenheit (°F) as follows: | ||
| °F = 32 + (°C * 1.8) | ||
VERTICAL DATUM
The vertical datum currently used throughout the Great Lakes is the International Great Lakes Datum of 1985 (IGLD 1985), although references to the earlier datum of 1955 are still common. This datum is a dynamic height system for measuring elevation that varies with the local gravitational force, rather than an orthometric system, which provides an absolute distance above a fixed point (Coordinating Committee, 1995). The primary reason for adopting a dynamic height system within the Great Lakes is to provide an accurate measurement of potential hydraulic head. The reference zero for IGLD (1985) is a tide gage at Rimouski, Quebec, which is located near the outlet of the Great Lakes-St. Lawrence River system. The mean water-surface elevation at the Rimouski, Quebec, gage approximates mean sea level.
HORIZONTAL DATUM
Horizontal coordinates (northings and eastings) used in this report are based on the Michigan State Plane Coordinate System of 1983 (SPCS 83), which is a projection that is referenced to the North American Datum of 1983 (NAD 83). In particular, the southern zone (2113) of Michigan SPCS 83 is a Lambert conformal conic projection based on a southern standard parallel of 42° 06¢ N, and a northern standard parallel of 43° 40¢ N. The latitude of the grid origin is 41°30¢ N and the central meridian is 84°22¢ W. The northing value at the grid origin is 0 meters and the easting of the grid origin is 4,000,000 meters (13,123,360 International ft). Michigan SPCS 83 is based on an ellipsoid of the earth’s surface described by the Geodetic Reference System of 1980 (GRS 80). Corpscon for Windows, U.S. Army Corps of Engineers (2003), can be used to convert coordinates between Michigan SPCS 83 and NAD83 systems, when conversions between state plane and geographic (latitude and longitude) coordinates are needed.