Study Of Historical Evolution Of Luoma Lake

As a major lake in the northern Jiangsu,Luoma Lake has been a water reservoir controlling the water level of the Great Canal since its existence.It has been through many changes.Based on the documents since 1128,this essay is devoted to an elaborate analysis of the formation and evolution in its history,utilizing statistic,and graphic digital methods.The results are as follows:(1)The migrating south of the Yellow river is the direct cause of the evolution of Luoma Lake.Since then,the evolution has been under the dual influence of the Yellow River and the Great Canal.Meanwhile,it displays distinctly a rhythmic change under human interference.In the history,Luoma Lake has been through five periods of evolution: the muti-lakes coexistence period from Nansong Dynasty to Wanli era,the deposition period from Tianqi era to early Qing Dynasty,the extension period from Kangxi to Qianlong era,the dying period from late Qing Dynasty to 1949 and the rejuvenation period from the foundation of P.R.C.till now.(2)Based on the study of the evolution of Luoma Lake,this essay conducts a further analysis of the causes of its formation and driving forces of its evolution,and draws the conclusions as follows:a.The variation of the surrounding water environment is highly related with the evolution of the Lake.While the variation process is mainly indicated by the repeated transformation of water conservancy projects on the drainage pattern.Under the strong intervention of human activity,Luoma Lake unremittingly reversed and rejuvenated from siltation under the natural conditions,and thus expanded its area.Meanwhile,Luoma Lake complemented numerous disadvantages of geographical environmental factors which appeared in the process of utilization,and formed the current stable condition.b.Deposition is the main cause of Luoma Lake's shrinking.The early period of its evolution is mainly influenced by the Yellow River,while the evolution in the period after 1949 is dominated by the Yi River.c.The reclamation of beach also has a negative impact on the evolution process,it is not the main factor that leads to its shrinking in the late period though.The shrink or expansion is subject to itself.d.There are certain effects of climate factors on the variation of Luoma lake.But the impact of its combined action with human is complicated.The impact on the shrink or expansion of the Lake cannot be generalized.Therefore the specific effects still need to be explored.(3)It is clear from its evolution that the unique social value is the underlying cause which leads to its ups and downs.While the value is derived from its special location at the junction of the three rivers: the Yellow River the Yi River and the Great Canal.At the same time,the social environmental factors are also important to the rhythmic change of the lake.