The Yellow River Delta is an alluvial plain formed by sediment deposited in the Bohai Sag, or marine trough, by the Yellow River Estuary. The Yellow River Delta is rich in oil and gas, water and land resources, offering great economic benefits for Dongying's development. Due to its fortuitous location, it has formed a unique ecosystem. The Shandong Yellow River Delta National Nature Reserve was established here, and relying on its rich wetland resources, the city's tourism industry has flourished.