The topography of Dehradun is defined by its basin-like structure. The Doon Valley is elevated, with the city sitting at an average altitude of 640 meters (2,100 feet) above sea level. It is completely landlocked and bounded by distinct geological features: the steep, rugged slopes of the Lesser Himalayas to the north and the heavily forested Shivalik Hills to the south.
The valley floor is relatively flat but gently sloping, drained by several perennial and seasonal streams, most notably the Asan and Song rivers, which ultimately feed into the Yamuna and Ganges systems. The terrain becomes rapidly steeper on the city's northern edges as one travels toward the hill station of Mussoorie.