Cleaning out creek channel with Bobcat 321

Major problem.....while sitting on sand and gravel in creek and dipping out channel in front of culvert;

the sand and gravel under me began to flow as water squirted out.

Then I managed to get out with little time to spare.Should I dig a hole upstream, collect the water and pump it

out as I work cleaning out the channel moving from upstream to down stream?

Cleaning out creek channel with Bobcat 321