Stable Isotope Hydrology Process Research In Puzhehei Peak Forest-lake Basin

Due to the dual role of human interference and natural environment,vegetation was destroyed in different degree of peak forest basin area,through the protection of human and natural restoration,vegetation appears successional stages.During this study,this paper through the comprehensive research method of stable isotope and hydrochemical tracer,according to sources in the vertical and horizontal structure of water layer behavior and precipitation distribution of synchronous observation,reveal the function and effect of vegetation water conservation on runoff;According to the water stable isotope of aquifer and chemical abundance information,revealling the water source,storage and transformation the process of water,and to provide the scientific basis for the vegetatio n landscape pattern adaptation.Based on the different water stable isotope characteristics of peaks Puzhehei lake basin area were analyzed,we obtained the following conclusions:?1?Characteristics of hydrogen and oxygen stable isotopes in precipitationThe ?D,?¹⁸O in precipitation of peak forest basin has obvious seasonal changes with negative ?value in rainy season and positive ?value in dry season.Both temperature and precipitation effect of peak forest-lake basin were weak.?2?Characteristics of hydrogen and oxygen stable isotopes in soil of different forest standWith the increase in soil depth,the variation of ?D in subsurface soil water shown decreased in all the four different types of forest stand.The ?D in deeper soil water less than the value in subsurface soil water in both secondary forest and pine forest stand,but the change trend was quite the contrary in shrub forest stand and bare land.These results indicate that different land use pattern have different infiltration mechanism of precipitation.?3?Characteristics of hydrogen and oxygen stable isotopes in surface waterHydrogen and oxygen stable isotopes in surface water has obvious the spatial and temporal variation characteristics with negative value of ?D and ?¹⁸O,but positive value of ?D and ?¹⁸O in dry season.The value of ?D and ?¹⁸O at downstream was higher than the value upstream,and fluctuates around-6.57‰(average value of ?D and ?¹⁸O in precipitation).?4?Characteristics of hydrogen and oxygen stable isotopes composition i n plant xylem wate rThe value of ?D and ?¹⁸O of xylem water varied widely in different plant.The value of ?¹⁸O in xylem water from more to less in proper order are: secondary forest,artificial forest,shrub.Hydrogen and oxygen stable isotopes of xylem w ater in dry season from more to less in proper order are:secondary forest,shrub,artificial forest,and the value of isotopes high than the value in rainy season,because of the precipitation had little difference.?5?Characteristics of hydrogen and oxyge n of the water source of plantsSecondary forest: During rainy season,water source of Pistacia weinmannifoliawas derived meanly from surface soil water,Quercus franchetii was derived meanly from surface soil water and precipitation.The water utilizatio n of young Pistacia weinmannifolia was meanly derived from subsurface soil water,adult Pistacia weinmannifolia main use of groundwater.The water utilization of young and adult Quercus franchetii were derived from subsurface soil water.During dry season,bulk of the vegetation in secondary forest mainly utilize middle and deeplayer soil water,and the utilization rate of subsurface cavern water and subsurface soil water increased.The water utilization of young and adult Pistacia weinmannifolia were derived from deep layer middle layer soil water and groundwater respectively.The water utilization of young and adult Quercus franchetiiwere derived from deeper soil water and ground water.Shrub: During rainy season,Pistacia weinmannifolia tend to use the surface soil water and surface water,Cinnamonum camphor mainly by atmospheric precipitation and surface soil water,Bauhinia brachycarpa and Pterolobium punctatum Kurzmainly by the middle and deep soil water and groundwater.During the dry season,the main use of deep soil water and groundwater.Artificial forest: During rainy season,Pinus yunnanensis vartenuifoliwas influenced by the atmospheric precipitation,which mainly used the shallow soil water and the surface karst water.The dry season,the adult of Pinus yunnanensis vartenuifoli mainly use groundwater and surface karst spring,the young Pinus yunnanensis vartenuifoli mainly use surface soil water and epikarst water.?6?Mechanis m of water source depletion in the water source of the lake basin in PuzheheiThere is a synergistic action between the process of vegetation restoration and regulation function of water-bearing stratum in watershed.It is therefore proposed that rehabilitating and restoratiing the secondary forest in the upstream area,restoratiing shrub in the middle and lower reaches of basin and enhancing the regulation function of watershed.