The Study Of Spatial And Temporal Changes In Water Systems Of Tongxiang Based On Remote Sensing

Tongxiang is a typical water town city in the South of the Yangtze River.The development of the urbanization make huge changes in water system space of Tongxiang.With the implementation of the regional tourism development strategy,water system plays a more prominent role in the development of Tongxiang,and it is an important work to optimize the quantity,pattern and functionality of water system.In this paper,the information of the water system in 1975 and 2016 are obtained through visual interpretation of high-resolution historical remote sensing images and domestic high-resolution remote sensing data.Then,spatial superposition analysis,water system pattern analysis,landscape pattern index,and nuclear density estimation were used to analyze the temporal and spatial variation of the quantity composition and spatial distribution of rivers and ponds in Tongxiang from 1975 to 2016.Finally,preliminary analyzes the reasons for such changes,and puts forward the water system optimization of the pattern of the some Suggestions in the future.The main results are as follows:(1)Temporal and spatial variation of river system.(1)The river system area of Tongxiang shows a decreasing trend,with the total area decreasing from 37.98 square kilometers in 1975 to 33.92 square kilometers in 2016.The main reduction is in the end tributary system.(2)From the perspective of river composition,the area of first-grade river channel shows an increasing trend,which is related to the excavation and thinning of artificial river channel such as Changshan River.There has been a significant reduction in grade 2 and 3 channels,mainly in the northeast centering on Wutong Street and Zhouquan town in the east of Tongxiang.(3)From the perspective of land type transformation,the rivers in the central urban area are mainly transformed into construction land,and the land types in Zhouquan town,Dama town and other areas far from the center are mainly transformed into cultivated land.(4)The trend of river trunk is obvious,and the connectivity is on the rise.(2)Temporal and spatial variation of pond water system.(1)The total scale of the pond water system in Tongxiang city shows an expanding trend,from 3.13 square kilometers in 1975 to 15.54 square kilometers in 2016.In addition,the quantity of ponds and the average area increase to different degrees.(2)The new construction of breeding pits and landscape ponds is the main source of the increase of ponds in the study area.(3)Only 0.34 square kilometers of historical ponds were retained,of which 0.20 square kilometers were converted into breeding pits,mainly distributed in the southwest of Tongxiang.(4)The newly added ponds,mainly distributed in the western towns of Tongxiang,are the main types of breeding pits.Second,the reduction is the landscape pond,which mainly distributed in the urban center.(5)The disappearance of the ponds is mainly concentrated in the northeast and southwest corner of Tongxiang,where the water systems are relatively developed,such as Wuzhen town and Chongfu Town.The ponds mainly converted to construction land,arable land and rivers.(6)The overall distribution of the pond is an aggregation distribution.The density of pond point has increased greatly,in space appear high in the west and low in the east of characteristics.Among them,except Fengming Street,the pond of each township shows a trend of more and more aggregation.(3)Based on the current situation of the development of Tongxiang city water system,the change trend and the future development strategy,four future Tongxiang drainage development Suggestions were put forward:(1)Moderately increase water surface rate.(2)promote water and farmland co-existence.(3)Create a water system with water town characteristics.(4)Hierarchical classification to develop water system control method,not only strengthen the drainage and coast protection,and provide support for reasonable compound use.