Geomorphologic changes in the lower Pearl River Delta, 1850-2015, largely due to human activity

We use 165 years of navigational and bathymetric data and 60 years of sediment discharge data to document and explain geomorphic changes in the Pearl River Delta (PRD) and its estuary, which in recent years has experienced rapid urbanization and explosive economic growth. A series of British and Chinese navigation charts dating back to 1850 show that since then the PRD has gained 1160 km2 of new land, most of it reclaimed land derived from disposal of dredge spoils. Accordingly, the PRD estuary has decreased by 35% in ocean area and by 39% in water volume. Changes were most dramatic in the western part of the delta, where the Modaomen and Huangmao seas decreased in ocean area by 62% and 39%, respectively. To the east, upper Lingding Bay (LDB) decreased in ocean area by 36%; in contrast, the lower part of LDB decreased by only 3% in area, although shoaling more by than 2 m, some of which may come via influx of sediment from the South China Sea. Since 1995 the rate of land accretion in the PRD has declined to 40% of what it was over the previous 145 years, and to <30% of what it was the previous 25 years, probably in response to less fluvial input because of river damming and river sand mining, as well as increased use of dredged sediment for construction. With decreased sediment supply and accelerated sea-level rise, the Pearl River delta may well begin to experience land loss and coastal inundation in the not-too-distant future.