| The process of river runoff sediment is the result of the change of regional ecological environment.It not only directly causes the scour and silting evolution of river channel,but also produces unpredictable effect on the engineering,wetland,environment and biodiversity of the basin.As the first tributary of Jinsha River,Longchuan River is one of the important runoff and sediment source area.The changes about runoff and sediment have an important influence on the construction of the Southwest hydropower base in China and ecological shelters in the middle and upper Yantze River,meanwhile,affect the development of Central Yunnan Economic Zone.So the research has important theoretical and practical significance which research the response between the process of runoff and sediment and the evolution of landscape pattern in the Longchuan River basin.Based on physical geography,hydrology and landscape ecology,applying the methods of RS,data statistics and so on,combined with the hydrological and meteorological data,the variation of runoff and sediment and the dynamic change of landscape pattern were analyzed respectively.The response between the change of runoff and sediment and the dynamic change of landscape pattern were explored.So the research can provide reference for making land use plan,controlling soil erosion and improving the local ecological environment.The results of research indicated as followed:(1)The annual runoff and sediment of Longchuan River had an extremely uneven distribution in the period of 1970-2012.The annual runoff distribution is uniform after 1992,while the amount of sediment has become increasingly uneven.Moreover,both of them showed no obvious downward trend.And they experienced four phases: the first was rise from 1970 to 1974,the second was decline from 1974 to 1984,the third was rise from 1984 to 2002 and the last was decline from 2002 to 2012.(2)Landscape fragmentation of the Longchuanjiang River basin tended to deepen during 1989-2009.But landscape fragmentation has improved since 2000.And landscape types in the landscape distribution were uniform.Landscape dominance decreased significantly.And the change of landscape agglomeration was small,the distribution of landscape types is more concentrated and simple,and landscape consist of a few large patches.The patch shape of Woodland,grassland and arable land was more complex,other landscape types' patch shape was simple.Influencing from human,the patch shape of grassland and building land became more complex,especially after 2000.But the forest land,cultivated land and unused land were oppose.The landscape fragmentation of grassland,building land and water area tended to weaken,especially building land,but the others on the contrary.(3)During the 1989-2009 years,the annual land use change rate of the Longchuan River Basin was small.The construction land,water area and grassland area increased,but the woodland and unused land changed decreased.Moreover,the change of watershed area,forest land and cultivated land is not big,grassland change tends to be stable,and the unused land's transform has the biggest change.(4)The response of Runoff variation to Basin's landscape pattern dynamic was more sensitive than sediment in Longchuanjiang River during 1989-2009 years,especially the previous year.Although the change of runoff and sediment discharge is significant to the change of grassland and farmland landscape pattern,the runoff response is more prominent in the last two years.In response to changing relationship between water and sediment on the landscape fragmentation degree,agglomeration degree and other types of woodland and farmland area change is obvious. |
PDF Full Text Request