| As a clean and renewable green energy source,hydropower brings good economic and social benefits,but also brings certain ecological and environmental impacts.This paper selects a typical area in the Xiaojiang River Basin for ecological investigation and research,and mainly adopts field sampling and experimental analysis to effectively identify the impact of power plant development in the basin on the biodiversity status and ecosystem integrity of the waters and its banks;and In conjunction with the actual planning work,the study was carried out to explore the types of small hydropower cleanup and reform assessment and the study of small hydropower cleanup and reform programs.The main conclusions of this paper are as follows.(1)The impact of hydropower development on terrestrial ecology in the Xiaojiang River Basin is small from a watershed perspective and only affects a local scale.The average vegetation cover within the whole basin was 0.433 in 1990,0.570 in 2002,0.552 in 2010,and 0.657 in 2019,and the overall vegetation cover within the basin has shown an increasing trend from 1990 to the present.The impact of local-scale hydro energy development on the vegetation in the watershed mainly exists during the construction period of hydroelectric power stations,the deforestation of vegetation due to the occupation of power station structures,and the inundation of vegetation due to the storage of water in large reservoirs.No rare and protected wild plants have been found in the vicinity of existing power stations in the Xiaojiang basin.The impact of hydropower development on terrestrial animals is not significant,mainly affecting the foraging of some birds.(2)Hydropower development in the Xiaojiang River Basin has some impact on aquatic ecology.Hydropower development in the basin has caused significant differences in the species and distribution of phytoplankton and benthic animals.The diatom phylum is dominant in the basin as a whole,followed by the cyanobacteria and green algae phylum,and the green algae phylum is dominant in the water-reducing reaches of most power stations.The zooplankton in the basin is dominated by rotifers and protozoa,and some river sections have a single species of zooplankton.The benthic animals in the pebble or gravel riverbed are mostly arthropods;in the fine sand or silt riverbed,the mosquito family,the mosquito family,the larvae of the mosquito family and the earthworm family are dominant;in sufficient water,slow flow,deeper water,the species and number of mollusks have increased,and the species that like to live in flowing water such as mayflies,stoneflies and stoneworms are relatively few.The impact of hydropower development on fish is mainly reflected in the fish in mountain rivers.The damming of the terrace power station blocks the migratory passage of fish in rivers,resulting in the obstruction of fish growth and reproduction.(3)In the cleanup and reform of small hydropower,in addition to conforming to policies and regulations,more attention should be paid to the protection of ecological environment,and different types of power stations should carry out different scientific cleanup and reform work.The evaluation criteria of the reserved,withdrawn and reformed power stations should be based on the "three lines and one list" and the green small hydropower evaluation criteria,combined with other conditions for a comprehensive evaluation,and the cleanup and reform of small hydropower should be carried out according to the evaluation results.In this paper,we design a cleanup and reform idea based on "three lines and one list" and green small hydropower evaluation,refine the criteria of small hydropower evaluation types,add one new category for retention,five new categories for withdrawal,and three new categories for reform.And the three different types of retention,withdrawal,rectification and reform of the corresponding cleanup and reform proposals. |
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