Complex sentence: Due to deforestation and increased agricultural use upstream, the river eroded much of the northern bank and widened the gap between Analostan Island and the shore and simultaneously large deposits of silt built up around Analostan Island.
Split into simpler sentences: Due to deforestation and increased agricultural use upstream, the river eroded much of the northern bank and widened the gap between Analostan Island and the shore. Simultaneously, large deposits of silt built up around Analostan Island.