Research On The Dynamic Change And Development Of Land Cover And Water Retention Of Liandu,Lishui

This paper takes Zhejiang city of Lishui province Liandu area as the study area.Based on 1994,2001,2008 and 2015 land cover types,by using the InVEST model to evaluate the quantitative and spatial dynamic of water conservation functions of the research area.Based on the difference of water conservation function,the important levels were classified,and the influence factor of water conservation function of stepwise regression analysis.At the same time according to the changes of land cover types of history,using the CA-Markov model to predicted the future land cover of study aera.And then by using InVEST model to simulate the water retention of study area in the future.The main results are as follows:(1)The land cover of study area changed a lot in 21 years.the Coniferous and broadleaved mixed forest area increased 14203.26hm~2,broad-leaved forest and bamboo forest area were increased by 10564.74hm~2 and 8539.03hm~2;and also the town area increased by 6111.72hm~2;the bare land and coniferous forest area were reduced by 19155.60hm~2 and 20803.77hm~2.(2)The water conservation depth of study area in1994,2001,2008 and 2015 were 95.18 mm,113.63 mm,82.36 mm,140.42mm;the total water retention were 1.43×108m3,1.70×108m3,1.23×108m3,2.10×108m3.In the southern area of the study area,the water conservation function is the best,followed by the northern region,the central region water conservation function is the worst.The water conservation function of mixed coniferous broad leaved forest,broad leaved forest and coniferous forest in the study area was the best,bare land,farmland and urban was the weakest.(3)The water conservation function of study area from 1994 to 2015 period increased by 47.53%,Different trends of water conservation function in different stages,during the period from 1994 to 2001,the water retention increased by 19.39%,during the period from 2001 to 2008,the water retention increased by 27.52%,from 2008 to 2015 increased by 70.50%.During the period from 1994 to 2001,the water conservation function of the northern region grew rapidly,during the period from 2001 to 2008;the overall study area was downward trend,the central declined rapidly;during the period from 2008 to 2015 around the water conservation function of growth is rapid,and Lixingshezuxiang increased fastest.(4)The study area of 1994,2001,2008 and 2015,the water conservation important zone were 4.31×104hm~2?5.75×104hm~2?3.32×104hm~2 and 9.13×104hm~2,The proportion of study area respectively 28.74%,38.35%,22.14% and 60.94%,the study area in 21 years increased by 111.83% important water conservation area.During the period from 1994 to 2015,the main characteristics of the major changes in the study area were that the low grade water conservation function area was transformed into a high grade water conservation function area,which was transformed into an important area of water conservation.(5)The main factors that affect the water conservation function of the study area can be divided into two types: climatic factors and underlying surface features.Precipitation is the main factor influencing factors,and the partial correlation function of water conservation reached 0.678,showed a significant positive correlation;surface soil saturated hydraulic conductivity and the urban area ratio as the main factors,and the water conservation function of partial correlation respectively reached 0.745 and-0.446.(6)According to the study area from 2022 to 2036 land cover types and water conservation function simulation and prediction results show that the study area of broadleaved forest area increased 3869.7hm~2,coniferous forest area decreased by 1782.9hm~2,the urban area increased by 2159.01hm~2.During the period from 2022 to 2036,the water conservation depth increased by 28.51 mm,and the total amount of water conservation increased by 0.43×104m3.Through the study of land cover change analysis evaluation type and function of water conservation,water resources protection as the study area to better play the function of water conservation,to provide theoretical reference and basis for the government and relevant decision-making departments to formulate development planning of water conservation function protection.