CUTLER, Calif. — Jayden Martinez walked across the cracked mud of the canal that flooded his family’s home last month, his Pokemon-themed Crocs crunching on pieces of concrete and rocks. Standing on the bank, the 9-year-old looked at the channel, partially clogged with trash, and recounted how the surging water broke through, turning his street into a river and leaving his family and neighbors 10 minutes to grab what they could and get out.