Journal of Geographical Sciences ›› 2007, Vol. 17 ›› Issue (2): 197-211.doi: 10.1007/s11442-007-0197-4

• Climate and Environmental Change • Previous Articles     Next Articles

Impacts of the large amount of sand mining on riverbed morphology and tidal dynamics in lower reaches and delta of the Dongjiang River

JIA Liangwen1, LUO Zhangren2, YANG Qingshu2, OU Shuying2, LEI Yaping2   

  1. 1. Coastal Ocean Research Center, Sun Yat-sen University, Guangzhou 510275, China|
    2. Institute of Estuarine and Coastal Research, Sun Yat-sen University, Guangzhou 510275, China
  • Received:2006-12-25 Revised:2007-02-11 Online:2007-06-25 Published:2007-06-25
  • Supported by:

    The 973 Project, No.2002CB412407

Abstract:

The sand dredging and its impacts on riverbed evolution and tidal dynamic change in the lower reaches and delta of the Dongjiang River are examined in this paper. The large amount of sand, totally 3.32 billion m3 from 1980 to 2002, was mined from the riverbeds of the lower reaches and delta of the Dongjiang River. Increasing of the channel capacity, lowering of the average riverbed elevation, deepening of the water depth and decreasing of the longi-tudinal riverbed gradient are the main effects on the riverbed evolution brought by the large amount of sand dredging. Under the strong sand dredging and associated significant riverbed deformation, the notable changes of the tidal dynamic in the lower reaches and delta of the Dongjiang River occurred, including: (1) in the upper reaches of the Dongjiang River delta and lower reaches of the Dongjiang River, tidal level dropped apparently, tidal range widened, flood tidal duration became longer, amplitudes for major tidal components became bigger and tidal dynamics intensified; (2) tidal wave spread faster; and (3) the limits of the tidal level, tidal current and salt water moved upstream.

Key words: Dongjiang River, sand mining, tide