Uttarakhand disaster is man-made it was caused by near by factories throwing waste into the lakes and rivers nearby. It was also caused by pipes being closed up by fallen trees and human-environmental interaction. These tremendous effects caused the Uttarakhand disaster and major harm to the community and people living there.
Yes, the Uttarakhand disaster was natural, because it was an act of God that humans cannot control. Humans cannot control whether an area floods. Of course, the human response could have been better, and more people could have been helped with provisions and evacuation sooner, but God caused the underlying flooding, not humans.
The Uttarakhand disaster was manmade in the fact that the deluge of rain was generally believed to be caused by global warming. The flooding was caused by lots of rain, which is a naturally-occurring thing. However, copious amounts of rain beyond what is normally expected during the monsoon season has been attributed to global warming.