Future impacts of freshwater resource management: sensitivity of coastal deltas

We present an assessment of contemporary and future effective sea-level rise (ESLR) using a sample of 40 deltas distributed worldwide. For any delta, ESLR is a net rate defined by eustatic sea-level rise, natural gross rates of fluvial sediment deposition and subsidence, and accelerated subsidence due to groundwater and hydrocarbon extraction. Present-day ESLR, estimated from geospatial data and a simple model of deltaic dynamics, ranges from 0.5 to 12.5 mm year -1 . Reduced accretion of fluvial sediment from upstream siltation of reservoirs and freshwater consumptive irrigation losses are primary determinants of ESLR in nearly 70% of the deltas, while for only 12% eustatic sea-level rise predominates. Future scenarios indicate a much larger impact on deltas than previously estimated. Serious challenges to human occupancy of deltas worldwide are conveyed by upland watershed factors, which have been studied less comprehensively than the climate change and sea-level rise question.

[1]  C. Vörösmarty,et al.  Anthropogenic sediment retention: major global impact from registered river impoundments , 2003 .

[2]  S. Lawrence Dingman,et al.  Effective sea-level rise and deltas: Causes of change and human dimension implications , 2006 .

[3]  D. Reed.  Sea-level rise and coastal marsh sustainability: geological and ecological factors in the Mississippi delta plain , 2002 .

[4]  L. H. Ochoa,et al.  Population and health data for Latin America. , 1993 .

[5]  M. Collins,et al.  The influence of fluvial sediment supply on coastal erosion in West and Central Africa , 1986 .

[6]  M. Collins,et al.  Fluviatile sediment fluxes to the Mediterranean Sea: a quantitative approach and the influence of dams , 2002, Geological Society, London, Special Publications.

[7]  D. Stanley,et al.  Nile Delta in its Destruction Phase , 1998 .

[8]  L. Miller,et al.  Mass and volume contributions to twentieth-century global sea level rise , 2004, Nature.

[9]  J. Syvitski,et al.  Impact of Humans on the Flux of Terrestrial Sediment to the Global Coastal Ocean , 2005, Science.

[10]  A. Sánchez-Arcilla,et al.  The Ebro Delta: Morphodynamics and Vulnerability , 1998 .

[11]  D. Walling,et al.  Recent trends in the suspended sediment loads of the world's rivers , 2003 .

[12]  John McManus,et al.  Deltaic responses to changes in river regimes , 2002 .

[13]  James N. Galloway,et al.  Pre-industrial and contemporary fluxes of nitrogen through rivers: a global assessment based on typology , 2004 .

[14]  Milliman Jd,et al.  Environmental and economic implications of rising sea level and subsiding deltas: the Nile and Bengal examples. , 1989 .