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Evapotrantaspiration is a crucial part of the hydrological cycle but few ground observatories for the Tibetan Plateau exist. In this study, we present lysimeter measurements from the growing season during seven years at a remote field location on the Tibetan Plateau. The measurements show rates between 2.5 and 3 mm·d−1 during the warmer months from June to August, dropping to 2 to 2.5 mm·d−1 in September. This results in a total volume of evapotranspiration of approximately 300 mm·yr−1 for the months from June to September. The inter-daily variability is however large, and comparison to meteorological variables suggest that this is largely driven by radiation and humidity. Data for a single season from a nearby flux tower allows us to compare the two common measurement methods for evapotranspiration in the field, showing an overall good agreement between the approaches. We also tested commonly applied models used to estimate evapotranspiration rates, namely the FAO-Penman-Monteith (PM) and the Priestly-Taylor (PT) model, which both make use of radiation data as well as the simpler Hargreaves-Samani (HS) and Rohwer (R) models which only need air temperature and wind speed as input. The most data intensive model (PM) has the lowest root mean square error (RMSE) (1.36 mm·d−1) and the mean bias error (MBE) (−0.05 mm·d−1) and reproduces the daily variability generally well. The much simpler HS model performs slightly worse (1.38 and 0.35 mm-d−1), but fails to reproduce the variability, due to its lack of information of local radiation and humidity data. Our results are in line with large scale estimates of evapotranspiration for the cold and arid region, provide a first long time series of in-situ measurements from a high elevation site and suggest that both the PM and HS models are appropriate when no direct measurements are available.
Li-Hui Wang; Xiao-Bo He; Jakob F. Steiner; Dong-Wei Zhang; Jin-Kui Wu; Shao-Yong Wang; Yong-Jian Ding. Models and measurements of seven years of evapotranspiration on a high elevation site on the Central Tibetan Plateau. Journal of Mountain Science 2020, 17, 3039 -3053.
AMA StyleLi-Hui Wang, Xiao-Bo He, Jakob F. Steiner, Dong-Wei Zhang, Jin-Kui Wu, Shao-Yong Wang, Yong-Jian Ding. Models and measurements of seven years of evapotranspiration on a high elevation site on the Central Tibetan Plateau. Journal of Mountain Science. 2020; 17 (12):3039-3053.
Chicago/Turabian StyleLi-Hui Wang; Xiao-Bo He; Jakob F. Steiner; Dong-Wei Zhang; Jin-Kui Wu; Shao-Yong Wang; Yong-Jian Ding. 2020. "Models and measurements of seven years of evapotranspiration on a high elevation site on the Central Tibetan Plateau." Journal of Mountain Science 17, no. 12: 3039-3053.
Glacier retreat caused by global warming alters the hydrological regime and poses far-reaching challenges to water resources and nature conservation of the headwater of Yangtze River, and its vast downstream regions with dense population. However, there is still lack of a robust modeling framework of the “climate-glacier-streamflow” in this water tower region, to project the future changes of glacier mass balance, glacier geometry, and the consequent impacts on runoff. Moreover, it is imperative to use the state-of-the-art sixth phase Coupled Model Intercomparison Project (CMIP6) to assess glacio-hydrology variations in future. In this study, we coupled a glacio-hydrological model (FLEXG) with a glacier retreat method (Δh-parameterization) to simulate glacio-hydrological processes in the Dongkemadi Glacier (over 5155 m.a.s.l), which has the longest continuous glacio-hydrology observation on the headwater of Yangtze River. The FLEXG-Δh model was forced with in-situ observed meteorological data, radar ice thickness, remote sensing topography and land cover data, and validated by measured runoff. The results showed that the model was capable to simulate hydrological processes in this glacierized basin, with Kling-Gupta efficiency (IKGE) of daily runoff simulation 0.88 in calibration and 0.70 in validation. Then, forcing by the bias-corrected meteorological forcing from the eight latest CMIP6 Earth system models under two climate scenarios (RCP2.6 and RCP8.5), we assessed the impact of future climate change on glacier response and its hydrological effects. The results showed that, to the end of simulation in 2100, the volume of the Dongkemadi Glacier would continuously retreat. For the RCP2.6 and RCP8.5 scenarios, the glacier volume will decrease by 8.7×108 m3 (74%) and 10.8×108 m3 (92%) respectively in 2100. The glacier runoff will increase and reach to peak water around 2060 to 2085, after this tipping point water resources will likely decrease.
Hongkai Gao; Zijing Feng; Tong Zhang; Yuzhe Wang; Xiaobo He; Hong Li; Xicai Pan; Ze Ren; Xi Chen; Wenxin Zhang; Zheng Duan. Assessing glacier retreat and its impact on water resources in a headwater of Yangtze River based on CMIP6 projections. Science of The Total Environment 2020, 765, 142774 .
AMA StyleHongkai Gao, Zijing Feng, Tong Zhang, Yuzhe Wang, Xiaobo He, Hong Li, Xicai Pan, Ze Ren, Xi Chen, Wenxin Zhang, Zheng Duan. Assessing glacier retreat and its impact on water resources in a headwater of Yangtze River based on CMIP6 projections. Science of The Total Environment. 2020; 765 ():142774.
Chicago/Turabian StyleHongkai Gao; Zijing Feng; Tong Zhang; Yuzhe Wang; Xiaobo He; Hong Li; Xicai Pan; Ze Ren; Xi Chen; Wenxin Zhang; Zheng Duan. 2020. "Assessing glacier retreat and its impact on water resources in a headwater of Yangtze River based on CMIP6 projections." Science of The Total Environment 765, no. : 142774.
In order to detect the source and controlling factors of hydrochemical ions in glacier meltwater-recharged rivers, the chemical characteristics of the river water, precipitation, and meltwater of the Dongkemadi River Basin, China, in 2014 (from May to October) were systematically analyzed, and combined with the hydrological and meteorological data. The results show that the hydrochemical pattern of the typical river was HCO3−-Ca2+. The most cations were Ca2+ and Mg2+, and the predominant anions were HCO3− and SO42−, in the river. The concentration of major ions and total dissolved solids (TDS) in the river water were much larger than that in the precipitation and meltwater. The TDS concentration was ordered: River water > precipitation > meltwater. The water-rock interaction and the dilution effect of the precipitation and meltwater on the runoff ions resulted in a negative correlation between the ion concentration of the river water and the river flow. The chemical ions of the river runoff mainly originated from rock weathering and the erosion (abrasion) caused by glacier movement. In addition, the contributions of different sources to the dissolved components of the Dongkemadi River were ordered: Carbonate (75.8%) > silicate (15.5%) > hydatogenic rock (5.7%) > atmospheric precipitation (3%), calculated by a forward geochemical model. And the hydrochemical weathering rates of carbonate and silicate minerals were 12.30 t·km−2·a−1 and 1.98 t·km−2·a−1, respectively. The CO2 fluxes, consumed by the chemical weathering of carbonate and silicate, were 3.28 × 105 mol·km−2·a−1 and 0.91 × 105 mol·km−2·a−1, respectively.
Tianding Han; Yuping Li; Jia Qin; Xiangying Li; Qin Yang; Xiaobo He. Hydrochemical Changes and Influencing Factors in the Dongkemadi Region, Tanggula Range, China. Water 2018, 10, 1856 .
AMA StyleTianding Han, Yuping Li, Jia Qin, Xiangying Li, Qin Yang, Xiaobo He. Hydrochemical Changes and Influencing Factors in the Dongkemadi Region, Tanggula Range, China. Water. 2018; 10 (12):1856.
Chicago/Turabian StyleTianding Han; Yuping Li; Jia Qin; Xiangying Li; Qin Yang; Xiaobo He. 2018. "Hydrochemical Changes and Influencing Factors in the Dongkemadi Region, Tanggula Range, China." Water 10, no. 12: 1856.
To obtain long term accurate high resolution precipitation for the Heihe River Basin (HRB), Weather Research and Forecasting (WRF) model simulations were performed using two different initial boundary conditions, with nine microphysical processes for different analysis parameterization schemes. High spatial-temporal precipitation was simulated from 2000 to 2013 and a suitable set of initial, boundary, and micro parameters for the HRB was evaluated from the Heihe Watershed Allied Telemetry Experimental Research project and Chinese Meteorological Administration data at hourly, daily, monthly, and annual time scales using various statistical indicators. It was found that annual precipitation has gradually increased over the HRB since 2000. Precipitation mostly occurs in summer and is higher in monsoon-influenced areas. High elevations experience winter snowfall. Precipitation is higher in the eastern upstream area than in the western upstream, area; however, the converse occurs in winter. Precipitation gradually increases with elevation from 1000 m to 4000 m, and the maximum precipitation occurs at the height of 3500–4000 m, then the precipitation slowly decreases with elevation from 4000 m to the top over the Qilian Mountains. Precipitation is scare and has a high temporal variation in the downstream area. Results are systematically validated using the in situ observations in this region and it was found that precipitation simulated by the WRF model using suitable physical configuration agrees well with the observation over the HRB at hourly, daily, monthly and yearly scales, as well as at spatial pattern. We also conclude that the dynamic downscaling using the WRF model is capable of producing high-resolution and reliable precipitation over complex mountainous areas and extremely arid environments. The downscaled data can meet the requirement of river basin scale hydrological modeling and water balance analysis.
Xiaoduo Pan; Xin Li; Guodong Cheng; Hongyi Li; Xiaobo He. Development and Evaluation of a River-Basin-Scale High Spatio-Temporal Precipitation Data Set Using the WRF Model: A Case Study of the Heihe River Basin. Remote Sensing 2015, 7, 9230 -9252.
AMA StyleXiaoduo Pan, Xin Li, Guodong Cheng, Hongyi Li, Xiaobo He. Development and Evaluation of a River-Basin-Scale High Spatio-Temporal Precipitation Data Set Using the WRF Model: A Case Study of the Heihe River Basin. Remote Sensing. 2015; 7 (7):9230-9252.
Chicago/Turabian StyleXiaoduo Pan; Xin Li; Guodong Cheng; Hongyi Li; Xiaobo He. 2015. "Development and Evaluation of a River-Basin-Scale High Spatio-Temporal Precipitation Data Set Using the WRF Model: A Case Study of the Heihe River Basin." Remote Sensing 7, no. 7: 9230-9252.
As a result of global warming, the depth of the permafrost active layer on the Qinghai–Tibet Plateau (QTP) has been increasing progressively during the past few decades. The Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, established the Binggou and Tanggula research stations on the QTP to monitor the impacts of snow pack and tundra soil on the permafrost active layer. In order to reproduce active layer dynamics in the present climate, the CoupModel, which calculates vertical heat and water processes in a soil–snow–atmosphere system, was successfully adjusted and applied for the two research stations. Subsequently, the calibrated model was used to provide an evaluation of the potential response of the active layer to different scenarios of climate warming and precipitation increase at Binggou station. The results reveal: ① the soil freezes deeper for snow depths less than 20 cm in the present climate, compared to the situation without snow cover. Increased albedo, due to shallow snow cover, reduces the absorption of solar irradiation and decreases soil temperature. However, this positive effect is lost with increasing precipitation and snow depth in winter. The decrease of simulated cumulative ground heat flux in winter along with thicker snow depth indicates that the thicker snow pack gradually insulates the subsoil against energy losses to the atmosphere in winter, which induces a reduction of active layer frozen depth. ② The model predicted an increase of maximum active layer thawing depth from today 150 cm to about 350 cm as a result of a 4 °C warming and a talik formation at the top of the permafrost as a result of a 6 °C warming. The other investigation concerns the influence of organic soil layer depth on the active layer at Tanggula station. The model results reveal that the maximum thawing depth of the active layer in summer gradually decreases along with the increase of the soil organic layer depth. The maximum thawing depth is close to 300 cm when ignoring the organic layer, while it is about 150 cm with a realistic organic layer of 40 cm depth. The results reveal that the organic layer provides a protection against active layer deepening in summer. Therefore, both the roles of snow and organic soil are of importance for the behavior of permafrost under climate warming conditions.
Jian Zhou; Wolfgang Kinzelbach; Guodong Cheng; Wei Zhang; Xiaobo He; Bosheng Ye. Monitoring and modeling the influence of snow pack and organic soil on a permafrost active layer, Qinghai–Tibetan Plateau of China. Cold Regions Science and Technology 2013, 90-91, 38 -52.
AMA StyleJian Zhou, Wolfgang Kinzelbach, Guodong Cheng, Wei Zhang, Xiaobo He, Bosheng Ye. Monitoring and modeling the influence of snow pack and organic soil on a permafrost active layer, Qinghai–Tibetan Plateau of China. Cold Regions Science and Technology. 2013; 90-91 ():38-52.
Chicago/Turabian StyleJian Zhou; Wolfgang Kinzelbach; Guodong Cheng; Wei Zhang; Xiaobo He; Bosheng Ye. 2013. "Monitoring and modeling the influence of snow pack and organic soil on a permafrost active layer, Qinghai–Tibetan Plateau of China." Cold Regions Science and Technology 90-91, no. : 38-52.