I would go with waterway=wadi because it is dry most of the time and only flowing with heavy rains. There is a note with this that states that it is also known as a wash in the deserts of America.America. At present adding intermittent=yes does not change the line on the map and it still shows as a solid line. waterway=wadi does give a pecked line indicating that it does not have flowing water all the time. I am attempting to get this changed to waterway=river-perennial / stream-perennial which has water all year round and is depicted by a solid blue line, next is waterway=river-nonperennial / stream-nonperennial which has water some of the year and is depicted with a pecked blue line, lastly is waterway=wadi which may only occasionally have water in very heavy rains and depicted with a brown pecked line. This may not happen but I am trying.

I would go with waterway=wadi because it is dry most of the time and only flowing with heavy rains. There is a note with this that states that it is also known as a wash in the deserts of America.