By Mohammed AtyCHIBAYISH MARSHES, Iraq, May 7 (Reuters) - After years of drought that left large swathes of Iraq's historic marshes cracked and empty, rising water levels are beginning to revive the wetlands, drawing buffalo herders and fishermen back to areas once abandoned.In Chibayish marshes in southern Iraq, canoes once again glide through waterways that had dried up in recent years, while water buffalo wade through restored marshland and patches of green pasture have reappeared.