20世纪80年代以来珠江三角洲网河区河性演变

Evolution of river characteristics in river network of Pearl River Delta since 1980s

针对20世纪80年代以来珠江三角洲网河受大规模采沙影响,其河道特性发生的显著变化,基于实测资料,从网河区河道的河床演变、水沙条件、同流量水位变化、西江和北江分流分沙变化、河槽容积及河道行洪能力等方面分析了珠三角网河区河性的演变情况。结果表明:20世纪80年代以来,网河区河床下切严重,来流量变化不大,来沙量大幅下降,同流量下水位下降明显,思贤滘对西江、北江的分水分沙有所调整,河槽容积增大,河道的行洪能力提高。随着规模取沙的减少,2005年后网河区河道进入新的平衡演变阶段。

Since 1980s, river characteristics in the river network of the Pearl River Delta in Guangdong Province, China, have significantly changed due to large-scale sand mining. Based on measured data, the recent evolution of river characteristics is analyzed from several aspects, such as riverbed evolution, flow and sediment conditions, variations of water level at equal water discharge, variations of flow and sediment diversion in the Xijiang and Beijiang rivers, the volume of river channel, and flood carrying capacity. The results show that since 1980s the riverbed of the river network has downcut severely, and the volume of coming water has slightly changed, while the volume of coming sediment has dramatically declined. Besides, the water level at equal water discharge has significantly dropped, and the flow and sediment diversion in the Xijiang and Beijiang rivers have been adjusted by river sand mining. Moreover, the flood carrying capacity has improved because the volume of river channel has increased. With the decrease of large-scale sand dredging operations, river evolution in the river network turned into a new equilibrium stage after 2005.