All operations must use simple gestures that need only a single touch. Gestures that need two fingers or complicated movements can be hard to operate for people with hand tremors or limited movement. Users with alternative input devices such as a mouth stick, sip-and-puff, or head mouse also benefit. Simple gestures are easier for someone with cognitive impairments to remember and use. If the site or application does use multi-touch gestures, be sure to also provide simple interfaces.
✗ Bad example: map application without zoom controls.
Google Maps mobile app only relies on pinch gesture for zooming.
✓ Good example: map application with zoom controls.
The TopoView map viewer application from the US Geological Service is a good example. It supports 2 fingered pinch and zoom gestures but also has + and - buttons to perform the same zoom actions. The + and - buttons are single pointer gestures. The application also supports touch and drag to pan around the map. To make this into a simple gesture, add up, down, left and right arrow buttons along the left hand navigation area. Now a user can pan around the map by clicking an arrow button. The screenshot below shows these added arrow buttons.
(Source: Knowbility article on pointer gestures)