Complex sentence: In former years the Rec was subject to periodic flooding from the River Avon, but a flood alleviation scheme in the 1960s improved the flow of the river, although the Rec remains part of the floodplain at risk of occasional flooding.
Split into simpler sentences: In former years the Rec was subject to periodic flooding from the River Avon, but a flood alleviation scheme in the 1960s improved the flow of the river. However, the Rec remains part of the floodplain at risk of occasional flooding.