20cm is like 8 inches of water. I'd wonder about water getting into the axle/brake caliper and/or onto the hot engine. But if it's not that deep, I don't see a problem. I mean, people ride in Oregon after it rains, so...
As a fellow Oregonian, I ride year round, and yes, some of that entails rain. A few 'detail' pointers I might add to what's already on offer are:
1) Cover the clutch lever with only 1-2 fingers.
2) Do most of your braking early... be as slow as you can be without losing stability, or to counter act effects of current (m/c gain stability with speed - that's why they are ungainly at parking lot speeds). If you must brake further only
use your rear
brake. Why? It is several cm/in. higher than the bottom 'puck' of the front calipers, therefore won't be inviting aquatic goo into the brake system. Once up to higher ground, and several wheel rotations, apply rear brake ever so gently just to 'scrape' shite off.
3) A page from MX, after braking, well prior to entering the water, move bum as far backward as one can (stand on pegs if you're so inclined) - leaving front wheel lighter, but more importantly shifting weight over the drive wheel, so in the event of a potential stall you can apply more throttle to move the bike literally to higher ground [(a la
4) If at all possible give the bike a good rinsing with clean water prior to parking; note esp. f/r suspension, and f/r brake rotors/calipers, and even chain/rear sprocket. And if you've spent the budget of a small African country on custom wheels I'd strongly advise a quick douche w/clean water.