黄河夺淮期间淮河入海河口动力、地貌与演变机制

DYNAMIC PROCESSES, GEOMORPHOLOGY OF THE HUAIHE RIVER ESTUARY AND ITS EVOLUTION MECHANISM ASSOCIATED WITH CAPIURE BY THE HUANGHE RIVER

根据历史文献资料，对黄河在淮期间淮河入海河口的动力条件、地貌特征及其演变机制进行了研究。结果表明，历史时期因大量多泥沙黄河径流汇入，淮河河口径流量、输沙量增大，但不同时期输沙量又受黄河下游反复进行的沿程淤积的影响而有变化。淮河口是中等强度的潮汐河口，其往复潮流和沿岸流系统非常有利于入海泥沙扩散。淮河口呈上窄下宽的喇叭口形，口门内、外侧分别发育有大规模拦门沙及水下三角洲，河口段河道具有典型的弯曲河型，自18世纪以后口门宽度有增大的趋势。淮河口演变的机制是潮流界不断向下游迁移、河口不断向海延伸，而且潮流界下移距离远大于同期河口外延距离，河口段长度急剧缩短。为了适应径流、潮流消能的需要，河口段河型向曲流化发展、口门展宽。古淮河人海河口和现代黄河河口具有不同的动力地貌特性和演变机制，其间不能作简单类比。

The HUanhe River discharged into the southem Yellow Sea through the Huanghe River estuary from 1128 to 1855 A. D, which resulted in flooding and waterlogging in the midddle and lower Huaihe River basin. on the othr hand, the modem channl of the lower Huanhe River is often taken as an analogy with the old Huanghe River. Therefore, in order to provide a theoretical foundation for appropriate hamssing Plans of both the Huanghe and Huaihe Rivers, it is neccessary to study the geomorphic evolution in the lower Huaihe mver basin. Howevef, except for the coasdine evolution of the old Huanghe mver delta since 1128 A. U, no ahention has been paid to the estuarine morphodynanic evolution of the Huanghe River estuary during 1128 to 1855 A. D.Based on historical liteares, this paper has discussed the dyAnc processes, geomorphology of the Huaihe River estuary during thes period of hme. Compared with the conteInporary Huanhe River,the Huaihe River estuary has a lareer runoff and silt dischnye which, was effected by the downfilling which took place in the lower Huanghe River valley for several times. The Huaihe estuary is a meso-tidal estuary with an average tide ranqe of over 3.2m. The tidal current and coastal current help silt diffuse into the Yellow Sea rapidy- The Huaihe River estuary is funnel-shaped with two crossing spits, a large bay mouth sand bar and submrged delta- The channl of the esmp has an obvious meandr form. The width of the mouth has a bend of increasing since 1700 A. n. During 1128-1855 A. D the hdal cimnt lindt ndgatd along the river continuously, and the estuary sbetohes toward the sea at the same hme. Because the tidal current lindt has a ndgrating disate much larges than the sbetohing disate of the mouth pasition, the length of the estuary channl below the tidal current limit becoms piogressively shoher. In response tO the energy dissipation and the reduchon the longitudinal gndent the estuarine channl developed a dishnchy meandring patterm- Thus, the Huanghe and the old Huaihe hivers have estuaries with different types, and there is no estuarine dynaxnorohic basis for the analogy between them.