The Global Positioning System (GPS) helps determine location. It was first developed in the mid-1970s by the US Air Force and later became available to the general public. GPS depends on a number of satellites circling the Earth and “beaming radio signals back to the surface”. A topographical map is designed to show the variation in elevations that can be found in specific geographic locations through the use of contour lines. The contour lines show the shape and elevation; the closer together the lines are, the steeper the increase in elevation. Topographical maps are designed to show natural (hills, valleys, rivers, etc.) and manmade features (roads, buildings, etc.). The “amount of detail shown on a map is proportionate to the scale of a map”. Water mapping is useful when planning a response to drownings in rivers or lakes. Google maps can provide a nice look over the body of water, helping to look at the basic lay of the land.