Complex sentence: The Central Marshes showed little recovery through 2003, but by early 2004 a patchwork of lakes had appeared in northern areas; there was flooding in southern areas which had previously been dry since the early 1990s.
Split into simpler sentences: The Central Marshes showed little recovery through 2003, but by early 2004 a patchwork of lakes had appeared in northern areas. There was flooding in southern areas which had previously been dry since the early 1990s.