As the cold winter floods usually drive the fish into slack water, either the deeps or slower current near banks, on the inside of bends and similar places these are the sort of places I would target. As finding the fish is half the battle local knowledge obviously pays off.
I prefer to fish my local smaller rivers as they will react quicker to rising conditions after a cold snap. During this period I would expect to catch chub, dace and a bit later roach and perch and the faster the flow the quicker the fish come back on the feed.
PS Regarding earlier comments on dace I can guarantee they will be in the same places March/April 'til at least November on my local rivers/streams - from then they can often take a bit of finding.
