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Aerosol optical properties and its direct radiative forcing over Tibetan Plateau from 2006 to 2017

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Particuology 2023年第3期74卷 64-73页

作者： Hongru Bi Siyu Chen Dan Zhao Fuquan Lu Yu Chen Yawen Guan Key Laboratory for Semi-arid Climate Change of the Ministry of Education Lanzhou UniversityLanzhou730000China Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Northwest Institute of Eco-Environment and ResourcesLanzhou730000China

Studies on optical properties of aerosols can reduce the uncertainty for modelling direct radiative forcing(DRF)and improve the accuracy for discussing aerosols effects on the Tibetan Plateau(TP)*** study investigated the spatiotemporal variation of aerosol optical and microphysical properties over TP based on OMI and MERRA2,and assessed the influence of aerosol optical properties on DRF at NamCo station(30°46.44′N,90°59.31′E,4730 m)in the central TP from 2006 to 2017 based on a long measurement of AERONET and the modelling of SBDART *** results show that aerosol optical depth(AOD)exhibits obvious seasonal variation over TP,with higher AOD500nm(>0.75)during spring and summer,and lower value(<0.25)in autumn and *** aerosol concentrations show a fluctuated rising from 1980 to 2000,significant increasing from 2000 to 2010 and slight declining trend after *** on sensitivity experiments,it is found that AOD and single scattering albedo(SSA)have more important impact on the DRF compared withαvalues and *** AOD440nm increases by 60%,DRF at the TOA and ATM is increased by 57.2%and 60.2%,*** SSA440nm increases by 20%,DRF at the TOA and ATM decreases by 121%and 96.7%,respectively.

关键词： Direct radiative forcing Aerosol optical depth Single scattering albedo Santa Barbara DISORT Atmospheric Radiative Transfer Model Tibetan plateau

Patterns,magnitude,and controlling factors of hydraulic redistribution of soil water by Tamarix ramosissima roots

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Journal of arid land 2013年第3期5卷 396-407页

作者： TengFei YU Qi FENG JianHua SI HaiYang XI Wei LI Research School of arid Environment and Climate Change Lanzhou University Cold and arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Gansu Hydrology and water resources Engineering Research Center

Tamarix spp. （Saltcedar） is a facultative phreatophyte that can tolerate drought when groundwater is not accessed. In addition to deep water uptake, hydraulic redistribution （HR） is another factor contributing to the drought tolerance of Tarnarix spp. In this study, data on soil volumetric moisture content （0）, lateral root sap flow, and relevant climate variables were used to investigate the patterns, magnitude, and controlling factors of HR of soil water by roots of Tamarix ramosissima Ledeb. in an extremely arid land in Northwest China. Results showed evident diurnal fluctuations in 0 at the depths of 30 and 50 cm, indicating ＂hydraulic lift＂（HL）. 0 increased remarkably at 10 and 140 cm but decreased at 30 and 50 cm and slightly changed at 80 cm after rainfall, suggesting a possible ＂hydraulic descent＂（HD）. However, no direct evidence was observed in the negative flow of lateral roots, supporting HR （including HL and HD） of T. ramosissima. The HR pathway unlikely occurred via lateral roots; instead, HR possibly occurred through adventitious roots with a diameter of 2-5 mm and a length of 60-100 cm. HR at depths of 20-60 cm ranged from 0.01-1.77 mm/d with an average of 0.43 mm/d, which accounted for an average of 22% of the estimated seasonal total water depletion at 0-160 cm during the growing season. The climate factors, particularly vapor pressure deficit and soil water potential gradient, accounted for at least 33% and 45% of HR variations with depths and years, respectively. In summary, T. ramosissima can be added to the wide list of existing species involved in HR. High levels of HR may represent a considerable fraction of daily soil water depletion and substantially improve plant water status. HR could vary tremendously in terms of years and depths, and this variation could be attributed to climate factors and soil water potential gradient.

关键词： drought tolerance phreatophyte hydraulic redistribution root sap flow Tamarix ramosissima

Effects of aeolian processes on nutrient loss from surface soils and their significance for sandy desertification in Mu Us Desert, China: a wind tunnel approach

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Journal of arid land 2015年第4期7卷 421-428页

作者： LANG Lili WANG Xunming WANG Guangtao HUA Ting WANG Hongtao Key Laboratory of water Cycle & Related land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

Mu Us Desert, a region with high aeolian activity, is at extremely high risk of sandy desertification. Using surface soil samples collected from Mu Us Desert of northern China, we evaluated the effects of aeolian processes on nutrient loss from surface soils by employing wind tunnel experiments. The experiments were conducted using free-stream wind velocities of 14, 16, 18 and 22 m/s. Our results showed that the fine particles （〈50 pm in diameter; 12.28% of all transported materials） carrying large nutrient Ioadings were exported outside the study area by ae- olian processes. After the erodible fine particles were transported away from the soil surfaces at low wind velocity （i.e. 14 m/s）, the following relatively high wind velocity （i.e. 22 m/s） did not have any significant effect on nutrient export, because the coefficients of variation for soil organic matter, total phosphorus, total nitrogen and available potassium were usually 〈5%. Our experimental results confirmed that aeolian processes result in a large amount of nutrient export, and consequently increase the risk of sandy desertification in arid and semi-arid ecosystems.

关键词： sandy desertification aeolian activity soil nutrients Mu Us Desert

Variations of precipitation characteristics during the period 1960–2014 in the Source Region of the Yellow River,China

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Journal of arid land 2018年第3期10卷 388-401页

作者： Mudassar IQBAL WEN Jun WANG Shaoping TIAN Hui Muhammad ADNAN Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou 730000 China University of Chinese Academy of Sciences Beijing 100049 China College of Atmospheric Sciences Chengdu University of Information Technology Plateau Atmosphere and Environment Key Laboratory of Sichuan Province Chengdu 610225 China division of Hydrology water-land resources in Cold and arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou 730000 China State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou 730000 China

Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a consequence of enhanced global hydrological cycle. The source region of the Yellow River（SRYR）, locating within the Qinghai-Tibet Plateau, is sensitive to the global climate change due to its complex orography and fragile ecosystem. To understand the precipitation characteristics and its impacts on the environment in the region, we studied the characteristics of rainy days and precipitation amount of different precipitation classes, such as light（0–5 and 5–10 mm）, moderate（10–15, 15–20 and 20–25 mm） and heavy（≥25 mm） rains by analyzing the precipitation data of typical meteorological stations in the SRYR during the period 1961–2014, as well as the trends of persistent rainfall events and drought events. Results showed that annual average precipitation in this area had a non-significant（P〉0.05） increasing trend, and 82.5% of the precipitation occurred from May to September. Rainy days of the 0–5 mm precipitation class significantly decreased, whereas the rainy days of 5–10, 10–15, and 20–25 mm precipitation classes increased and that of ≥25 mm precipitation class decreased insignificantly. The persistent rainfall events of 1-or 2-day and more than 2-day showed an increasing trend, with the 1-or 2-day events being more frequent. Meanwhile, the number of short drought periods（≤10 days） increased while long drought periods（〉10 days） decreased. Since the 0–5 mm precipitation class had a huge impact on the grasslands productivity; the 5–10, 10–15, and 20–25 mm precipitation classes had positive effects on vegetation which rely on the deep soil water through moving nutrients and water into the root zone of these vegetation or through the plant-microbe interactions; the ≥25 mm precipitation class contributed to the floods; and more persistent rainfall events and

关键词： precipitation characteristics climate change ecosystem water resources vegetation source region of theYellow River

Bursting oscillations in a hydro-turbine governing system with two time scales

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Chinese Physics B 2017年第12期26卷 609-616页

作者：韩青爽陈帝伊张浩 Institute of water resources and Hydropower Research Northwest A & F University Yangling 712100 China Key Laboratory of Agricultural Soil and water Engineering in arid and Semiarid Areas Ministry of Education Northwest A & F University Yangling 712100 China

A fast-slow coupled model of the hydro-turbine governing system （HTGS） is established by introducing frequency disturbance in this paper. Based on the proposed model, the performances of two time scales for bursting oscillations in the HTGS are investigated and the effect of periodic excitation of frequency disturbance is analyzed by using the bifurcation diagrams, time waveforms and phase portraits. We find that stability and operational characteristics of the HTGS change with the value of system parameter kd. Furthermore, the comparative analyses for the effect of the bursting oscillations on the system with different amplitudes of the periodic excitation a are carried out. Meanwhile, we obtain that the relative deviation of the mechanical torque mt rises with the increase of a. These methods and results of the study, combined with the performance of two time scales and the fast-slow coupled engineering model, provide some theoretical bases for investigating interesting physical phenomena of the engineering system.

关键词： bursting oscillations physical phenomena hydro-turbine governing system two time scales

Non-negligible factors in low-pressure sprinkler irrigation:droplet impact angle and shear stress

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Journal of arid land 2022年第11期14卷 1293-1316页

作者： HUI Xin ZHENG Yudong MUHAMMAD Rizwan Shoukat TAN Haibin YAN Haijun College of water resources and Civil Engineering China Agricultural UniversityBeijing 100083China Engineering Research Center of Agricultural water-Saving and water resources Ministry of EducationBeijing 100083China Semi-arid Agriculture Engineering&Technology Research Center of China Shijiazhuang 050051China

Droplet shear stress is considered as an important indicator that reflects soil erosion in sprinkler irrigation more accurately than kinetic energy,and the effect of droplet impact angle on the shear stress cannot be *** this study,radial distribution of droplet impact angles,velocities,and shear stresses were investigated using a two-dimensional video disdrometer with three types of low-pressure sprinkler(Nelson D3000,R3000,and Komet KPT)under two operating pressures(103 and 138 kPa)and three nozzle diameters(3.97,5.95,and 7.94 mm).Furthermore,the relationships among these characteristical parameters of droplet were analyzed,and their influencing factors were comprehensively *** various types of sprinkler,operating pressures,and nozzle diameters,the smaller impact angles and larger velocities of droplets were found to occur closer to the sprinkler,resulting in relatively low droplet shear *** increase in distance from the sprinkler caused the droplet impact angle to decrease and velocity to increase,which contributed to a significant increase in the shear stress that reached the peak value at the end of the ***,the end of the jet was the most prone to soil erosion in the radial direction,and the soil erosion in sprinkler irrigation could not only be attributed to the droplet kinetic energy,but also needed to be combined with the analysis of its shear *** comparing the radial distributions of average droplet shear stresses among the three types of sprinklers,D3000 exhibited the largest value(26.94-3313.51 N/m^(2)),followed by R3000(33.34-2650.80 N/m^(2)),and KPT(16.15-2485.69 N/m^(2)).From the perspective of minimizing the risk of soil erosion,KPT sprinkler was more suitable for low-pressure sprinkler irrigation than D3000 and R3000 *** addition to selecting the appropriate sprinkler type to reduce the droplet shear stress,a suitable sprinkler spacing could also provide acceptable results,because the distance

关键词： center pivot irrigation system water droplet universal model soil erosion water-saving irrigation

A GPU-based numerical model coupling hydrodynamical and morphological processes

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International Journal of Sediment Research 2020年第4期35卷 386-394页

作者： Jingming Hou Yongde Kang Chunhong Hu Yu Tong Baozhu Pan Junqiang Xia State Key Laboratory of Eco-hydraulics in Northwest arid Region of China School of Water Resources and Hydroelectric EngineeringXi'an University of TechnologyXi'an University of Technology China Institute of water resources and Hydropower Research State Key Laboratory of water resources and Hydropower Engineering Science Wuhan University

Sediment transport simulations are important in practical *** this study,a graphics processing unit(GPU)-based numerical model coupling hydrodynamical and morphological processes was developed to simulate water flow,sediment transport,and morphological *** at accurately predicting the sediment transport and sediment scouring processes,the model resolved the realistic features of sediment transport and used a GPU-based parallel computing technique to the accelerate *** model was created in the framework of a Godunov-type finite volume scheme to solve the shallow water equations(SWEs).The SWEs were discretized into algebraic equations by the finite volume *** fluxes of mass and momentum were computed by the Harten,Lax,and van Leer Contact(HLLC) approximate Riemann solver,and the friction source terms were calculated by the proposed a splitting point-implicit *** values were evaluated using a novel 2 D edge-based MUSCL *** code was programmed using C++and CUDA,which could run on GPUs to substantially accelerate the *** aim of the work was to develop a GPU-based numerical model to simulate hydrodynamical and morphological *** novelty is the application of the GPU techniques in the numerical model,making it possible to simulate the sediment transport and bed evolution in a high-resolution but efficient *** model was applied to two cases to evaluate bed evolution and the effects of the morphological changes on the flood patterns with high *** indicated that the GPU-based high-resolution hydro-geomorphological model was capable of reproducing morphological *** computational times for this test case on the GPU and CPU were298.1 and 4531.2 s,respectively,indicating that the GPU could accelerate the computation 15.2 *** with the traditional CPU high-grid resolution,the proposed GPU-based high-resolution numerical model improved the reconstruction speed more

关键词： Sediment simulation Shallow water equation Finite-volume method GPU

Copula-based identification of the non-stationarity of the relation between runoff and sediment load

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International Journal of Sediment Research 2017年第2期32卷 221-230页

作者： Shengzhi Huang Pei Li Qiang Huang Guoyong Leng State Key Laboratory Base of Eco-Hydraulic Engineering in arid Area Xi'an University of Technology Key Laboratory of water Cycle and Related land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences

It is important to identify the non-stationarity in the relation between runoff and sediment load under the backdrop of the changing *** relation helps to further understand the mechanisms of runoff and sediment yield.A copula-based method was used to detect possible change points in the relation between runoff and sediment load in the Wei River Basin(WRB),China,where soil erosion is a very severe *** modified Mann-Kendall trend test method was applied to obtain the trends of runoff and sediment load spanning 1960-2010 at monthly and annual ***,the causes of the identified non-stationarity of the relation between runoff and sediment load were roughly analyzed from the perspective of climate change and human *** indicated that:(1)the runoff and sediment load in the Jinghe and Wei rivers were generally characterized by noticeably decreasing trends at both monthly and annual timescales;(2)both the Jinghe and Wei rivers had a common change point(2002),implying that the stationarity of the relation between runoff and sediment load in the Jinghe and Wei River was invalid;(3)human activities including increasing water consumption and growing application of soil conservation practices are dominant factors resulting in non-stationarity in the relation between runoff and sediment load in the *** study provides a new idea for identifying the non-stationarity of multivariate relation in the hydro-meteorological field under the background of the changing environment.

关键词： Copula-based method Runoff Sediment load Non-stationarity Change point Human activities

Climate change and groundwater resources in Lao PDR

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Journal of Groundwater Science and Engineering 2017年第1期5卷 53-58页

作者： Khongsab Somphone OunakoneKone Xayviliya division of Groundwater Department of Water Resources MoNRE

The national economy of Lao PDR is highly dependent on water resources. Consequently, the sustainable management of groundwater and successful adaptations to future climate change are major concerns. Climate projections for Lao PDR predict increased rainfall and hot weather, with more intense rainfall events and more frequent and severe droughts and floods. Under climate change, reductions in the amount and quality of groundwater are two critical problems. Reductions of the groundwater level will restrict the access of local people to groundwater resources, thereby posing a threat to food security and livelihoods. Lao PDR suffers from a limited number of human resources with the requisite skills to perform groundwater investigations and provide sustainable management. For the successful implementation of groundwater management plans, limitations associated with funding and technology should be resolved via support from the government and international cooperation. Advanced action plans for capacity building and training courses should be established to strengthen administrative and individual capacities. Technical measures, such as groundwater monitoring, aquifer characterizations, and water treatment systems, should be implemented to manage future climate change and water resource security.

关键词： Groundwater water resource Climate change LaoPDR