River Modifications in the PRD
Urban growth is accompanied with substantial environmental change for the protection of property and to ensure economic productivity. The history of the Pearl River Delta is a story of human adaptation and modifications to a complex estuarine landscape, constantly redefining the relationship between human settlement and the water’s edge. In the past 50 years, unprecedented large-scale engineering efforts have altered the hydrology of the PRD to accommodate the rapid urbanization and industrialization of the region. These engineering projects are generally for flood control, the creation of land, transportation infrastructure, and resource extraction. The systematic changes to the river system in the PRD have caused significant environmental problems within the region, which reveal the inter-related nature of these engineering activities. For example, rapid urbanization has spurred extensive sand extraction in the rivers of the PRD to provide for construction material and fill for land reclamation. This lowering of the riverbeds weakens the river banks due to increased erosion, and increases the threat for saltwater intrusion. Other modifications such as the restructuring of rivers, land reclamation, and other large-scale construction also alter the behavior of the river systems in the PRD.
2030: Why Does 30cm Matter?
All flood control systems are engineered to particular “design years”, which indicates flood frequency in years. For example, the levee system near the mouth of the Jiaomen Channel in Nansha, is currently designed to withstand a storm that happens every 35 years, or 2.55 meters above sea level. With a uniform 30cm rise in sea level due to climate change, a storm that occurs once every one-hundred years will reach the same flood-stage once every 28 years, nearly four-times as often. This reduction in infrastructure “design years” means more-frequent flooding, and threatens the safety and productivity of the Pearl River Delta.