A PA-18 patrol pilot reported nosing over and damaging the prop after landing on a beach.

Narrative

I was on patrol [and] was the only person onboard the aircraft. I was landing on the beach. The purpose of the flight was game patrol. There were no injuries from the incident. The wind was blowing from the north at approximately 7 KTS. I was landing to the north into the wind. I touched down in sand and [the surface] then changed to small pebbles further up the beach. The touchdown was normal through the first three quarters of the landing roll. At the final part of the landing the tires sank into the sand and the aircraft rotated forward with the main landing gear remaining stationary in the sand. The propeller contacted the sand. The power was at idle throughout the entire landing roll. The aircraft propeller was bent backwards slightly from the impact. There was no damage to other property. The weather was partly cloudy and the sun was shining. Immediately after the incident I exited the aircraft. There was fuel spilling from the vent in the fuel cap on the right wing. I looped a rope around the fuselage section and pulled the tail down and stopped the flow of fuel. I had slept well the night before. I had been awake for 8 1/2 hours prior to the incident. Since my last sleep period I had been flying approximately one hour prior to the incident.