Mountain communities in Nepal are increasingly exposed to climate-induced shifts in water availability,driven by glacial retreat,altered precipitation/snowmelt regimes,and declining groundwater sources.This study pres...Mountain communities in Nepal are increasingly exposed to climate-induced shifts in water availability,driven by glacial retreat,altered precipitation/snowmelt regimes,and declining groundwater sources.This study presents an integrated framework combining hydrological source analysis with socio-demographic survey data to evaluate seasonal water contributions and communitylevel water use patterns in the Upper Marsyangdi catchment,Manang District,Nepal.Isotopic(δ^(18)O)and geochemical(silica)tracers were used in a Bayesian mixing model to quantify the seasonal contributions of glacial melt,snow,rain,and groundwater to river flow.Findings indicate that groundwater dominates pre-monsoon flow(60%-70%)while post-monsoon discharge reflects more balanced inputs from all sources.In parallel,120 household surveys were analysed using Latent Class Analysis to characterise water use across domestic,agricultural,energy,and tourism sectors.Results reveal spatial and demographic gradients in water source dependency,including gender and occupation as important predictors of water use.Respondents reported perceived increases in spring flow,alongside reductions in the availability of snow for household and tourism use and deteriorating river water quality and quantity,particularly affecting hydropower operations.Adaptation strategies include increased reliance on water storage infrastructure and source switching.The study highlights the value of applying probabilistic methods to hydrological and sociocultural data to identify vulnerable populations and inform targeted,context-sensitive adaptation strategies.The proposed framework is transferable to other high-altitude regions,offering a robust approach for assessing climate resilience through the synthesis of scientific and local knowledge systems.展开更多
Identifying plant water sources is fundamental for elucidating ecohydrological processes and improving water resource management in arid zones under climate change.Stable hydrogen and oxygen isotopes are commonly used...Identifying plant water sources is fundamental for elucidating ecohydrological processes and improving water resource management in arid zones under climate change.Stable hydrogen and oxygen isotopes are commonly used to trace plant water uptake;however,cryogenic vacuum extraction(CVE),the standard method for extracting plant xylem water,may induce deuterium depletion,thereby biasing source attribution.To systematically assess the effects of CVE-induced deuterium depletion across species,size classes,and habitats,we excavated five representative soil profiles along the mainstream of the Tarim River in northwestern China,in mid-July 2022.A total of 29 individuals,comprising both Populus euphratica and Tamarix ramosissima,were sampled.We divided P.euphratica individuals into four groups based on diameter at breast height(<50,50-100,100-250,and>250 cm),while categorized T.ramosissima individuals into four groups according to plant height(<1.0,1.0-2.0,2.0-4.0,and>4.0 m).Plant xylem water was extracted using CVE,and five deuterium depletion scenarios(-5.00‰,-7.00‰,-9.00‰,-11.00‰,and-13.00‰)were simulated.The Bayesian Mixing Model for Stable Isotope Analysis in R(MixSIAR)was applied under six input modes to quantify the proportional contributions of potential water sources and associated prediction errors.Model evaluation revealed that P.euphratica achieved the highest accuracy with a-9.00‰correction of depletion,whereas a-11.00‰ correction was optimal for T.ramosissima,reducing relative prediction errors by 68.65%and 67.73%,respectively,compared with uncorrected scenario.Small-sized P.euphratica individuals exhibited less deuterium depletion,whereas no clear size-dependent pattern was observed for T.ramosissima.Spatially,plant individuals located farther from the river exhibited reduced deuterium depletion in xylem water.Despite differences in species traits and habitat conditions,both species predominantly relied on deep soil water and groundwater,which together contributed,on average,61.45%and 59.95%for P.euphratica and T.ramosissima,respectively.These findings highlight the necessity of accounting for CVE-induced deuterium depletion when identifying plant water-use strategies and provide methodological guidance for isotope-based ecohydrological studies in arid environments.展开更多
基金funded by the Natural Environment Research Council’s Global Challenges Research Fund(NE/P016146/1)。
文摘Mountain communities in Nepal are increasingly exposed to climate-induced shifts in water availability,driven by glacial retreat,altered precipitation/snowmelt regimes,and declining groundwater sources.This study presents an integrated framework combining hydrological source analysis with socio-demographic survey data to evaluate seasonal water contributions and communitylevel water use patterns in the Upper Marsyangdi catchment,Manang District,Nepal.Isotopic(δ^(18)O)and geochemical(silica)tracers were used in a Bayesian mixing model to quantify the seasonal contributions of glacial melt,snow,rain,and groundwater to river flow.Findings indicate that groundwater dominates pre-monsoon flow(60%-70%)while post-monsoon discharge reflects more balanced inputs from all sources.In parallel,120 household surveys were analysed using Latent Class Analysis to characterise water use across domestic,agricultural,energy,and tourism sectors.Results reveal spatial and demographic gradients in water source dependency,including gender and occupation as important predictors of water use.Respondents reported perceived increases in spring flow,alongside reductions in the availability of snow for household and tourism use and deteriorating river water quality and quantity,particularly affecting hydropower operations.Adaptation strategies include increased reliance on water storage infrastructure and source switching.The study highlights the value of applying probabilistic methods to hydrological and sociocultural data to identify vulnerable populations and inform targeted,context-sensitive adaptation strategies.The proposed framework is transferable to other high-altitude regions,offering a robust approach for assessing climate resilience through the synthesis of scientific and local knowledge systems.
基金supported by the National Key R&D Program of China(2023YFC3206801)the National Natural Science Foundation of China(42171041).
文摘Identifying plant water sources is fundamental for elucidating ecohydrological processes and improving water resource management in arid zones under climate change.Stable hydrogen and oxygen isotopes are commonly used to trace plant water uptake;however,cryogenic vacuum extraction(CVE),the standard method for extracting plant xylem water,may induce deuterium depletion,thereby biasing source attribution.To systematically assess the effects of CVE-induced deuterium depletion across species,size classes,and habitats,we excavated five representative soil profiles along the mainstream of the Tarim River in northwestern China,in mid-July 2022.A total of 29 individuals,comprising both Populus euphratica and Tamarix ramosissima,were sampled.We divided P.euphratica individuals into four groups based on diameter at breast height(<50,50-100,100-250,and>250 cm),while categorized T.ramosissima individuals into four groups according to plant height(<1.0,1.0-2.0,2.0-4.0,and>4.0 m).Plant xylem water was extracted using CVE,and five deuterium depletion scenarios(-5.00‰,-7.00‰,-9.00‰,-11.00‰,and-13.00‰)were simulated.The Bayesian Mixing Model for Stable Isotope Analysis in R(MixSIAR)was applied under six input modes to quantify the proportional contributions of potential water sources and associated prediction errors.Model evaluation revealed that P.euphratica achieved the highest accuracy with a-9.00‰correction of depletion,whereas a-11.00‰ correction was optimal for T.ramosissima,reducing relative prediction errors by 68.65%and 67.73%,respectively,compared with uncorrected scenario.Small-sized P.euphratica individuals exhibited less deuterium depletion,whereas no clear size-dependent pattern was observed for T.ramosissima.Spatially,plant individuals located farther from the river exhibited reduced deuterium depletion in xylem water.Despite differences in species traits and habitat conditions,both species predominantly relied on deep soil water and groundwater,which together contributed,on average,61.45%and 59.95%for P.euphratica and T.ramosissima,respectively.These findings highlight the necessity of accounting for CVE-induced deuterium depletion when identifying plant water-use strategies and provide methodological guidance for isotope-based ecohydrological studies in arid environments.
