Ecological Environmental Assessment And Protection Of Water Source Construction Projects In Mountainous Area

With the impact of human activities such as interbasin water transfer,ecological construction,urbanization and global climate change,land use change and ecological environment status of water sources in mountainous areas have been related to water security and sustainable development of regional social economy.Danjiangkou reservoir area and its upper soil and water protect projection I and II area are the water resource of south-to-north water transfer(middle line).In recent years,many ecological and environmental projects have been implied to protect the water resources areas,such as the construction of ec ological clean small watershed unit,actively adjustmant of land use·structure and typies.Those ecological projects have improved the ecological environmental quality of water resources area,and the ecosystem service function have achieved to securitical state and sustainable development.In this paper,we choose the Shangluo city and Minjiahe ecological clean small watershed,which is the provincial demonstration area and water resource of upper soil and water protect projection I and ? area,as the research area.Based on the data collection,field investigation,field sampling and lab analysis combining the theories of land use planning,soil science,ecology and modern information technology,the spatial and temporal variation of land use and the response of ecological construction were analyzed.The relationship between the construction of ecological clean watershed and the response of soil organic matter,total nitrogen and anti-erosion capacity of cultivated soil was studied.The effects of horizontal terraces on the variation of soil organic matter and nitrogen content and spatial distribution were illustrated.The impact of ecological construction on the value and function of ecosystem services was discussed.The ecological security status and sustainable development trend of Shangluo water source area under ecological construction were evaluated.The main research results are as follows:(1)The change characteristics of land use type and structure in Shangluo water source area were expounded.From 2005 to 2014,the land use change of Shangluo water source area mainly showed as follows:more than 250°slope cultivated land was converted into forest,shrub grassland was converted into forest land and garden land,farmland,water area and unutilized land were converted into construction land,unutilized land was converted into arable land,and slope cultivated land was transformed into horizontal terraces.From 2014 to 2020,farmland and unutilized land in Shangluo water source area would be converted into forest land,garden land,grassland land and construction land.Woodland and arable land were the main land use types.The change of land use type was slow,and the degree of land use development was general.The landscape type diversity index,gibbs-Martin diversity index and evenness index were declining,while the dominance index was rising.It indicated that the land use structure of Shangluo water area had been gradually stabilized.(2)The response relationship of soil ecological environment of water source to the construction of ecological clean small watershed was expounded.Ten years after the river basin was constructed,the contents of soil organic matter and total nitrogen in the basin increased by 8.99g/kg and 0.44g/kg respectively.The reasonable type of land use was formed from the top to the bottom of the slope:soil and water conservation ecological woodland,sparsely forested and shrub grassland,sloping land for fallowing and horizontal terraces for stone.Broad-leaved mixed forests of trees and shrubs were more conducive to the improvement of soil organic matter,nitrogen and anti-erosion ability.The contents of soil organic matter and total nitrogen were increased by 7.8 g/kg and 0.21 g/kg respectively,while the soil ecosystem function of terraces on the river basin scale was higher than that of terraces on the field scale.(3)The response mechanism of ecological construction and the ecosystem service function of Shangluo water source area was revealed.From 2005 to 2014 and 2014 to 2020,the total value of ecosystem services in Shangluo water source area increased by 4.65 × 108 yuan and 0.87 × 108 yuan,respectively.In 2014 and 2020,the ecological sensitivity index of Shangluo water source area was 1.09 and 1.47 respectively,both less than 2,indicating that the research area was overall a low ecological sensitivity area during the ecological construction.In short,the ecological construction had improved the ecological environment quality of shangluo water source area and enhanced the ecosystem service function.(4)The effects of ecological construction on the ecological security of Shangluo water source area were evaluated.From 2005 to 2008,the ecological security of Shangluo water source area was in the state of heavy police,and immediately after 2009,it crossed the level of the medium police into the state of warning in 2009 and was in the early warning state from 2009 to 2011.The period from 2011 to 2012 was a critical period for the transition of the state of ecological security.After 2012,it started to enter a safer state from the early warning state.After 2012,the composite index continued to rise.This was in line with the successful completion and acceptance of the "Danzhi ?" project and the formal start-up of "Danzhi ?"construction projects.It showed that the ecological construction had improved the level of ecological security of the ecological environment of Shangluo water source area.(5)The effects of ecological construction on sustainable development of Shangluo water source area were expounded.From 2009 to 2020,the ecological footprint of Shangluo water source area increased year by year,and the ecological carrying capacity decreased year by year.The ecological pressure index increased year by year,but the index was between 0.8 and 1.2,which was an ecological balance area.The index of ecological diversity and development capacity showed an upward trend,and the index scale was similar.During the study period,the sustainable development of Shangluo water source area was in good condition.