Small aircraft pilot reported after landing the aircraft began to veer towards the right side of the runway. After applying full rudder and brakes the pilot reported being forced to turn off the magnetos and nose the aircraft over to prevent a runway departure into a nearby ditch. A prop strike resulted.

Narrative

On the afternoon of Date 1 I was acting as a volunteer pilot. I was hauling rides in Aircraft X. I was on my seventh flight of the day and the wind had changed directions from landing uphill on Runway XX to landing downhill on Runway X. I made a normal approach to land on Runway X; touched down normal; and on roll out the airplane started to roll to the right. I applied full left rudder and the airplane kept going to the right. This particular aircraft has separate pedals for the brakes than the rudders and you can not use both at the same time. I then needed to switch from rudders to brakes at which time I applied full brake and the airplane wasn't slowing down. I pumped the brakes up to regain pressure at which time I realized I was headed for the ditch next to the runway and that it would be best for the airplane and passengers if I went on my nose versus collapsing the gear in the ditch so I gave full aft stick and shut the engine off using the mag switch and one of the prop tips struck the pavement and I came to rest on my nose. No passengers were hurt; no fuel was spilled and other than the prop tip no damage was done to the aircraft. There were government employees present at the event. We then pulled the airplane back to straight and level and pulled it to the hangar. where we found lots of brake fluid leaking from the calipers. My takeaway from this is to more thoroughly inspect my equipment as the day goes on and take in to account wind changes earlier on. We will do better going forward.