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Dynamics and hotspots of soil erosion and management scenarios of the Central Rift Valley of Ethiopia

International Journal of Sediment Research 2012年第1期27卷 84-99页

作者： Derege Tsegaye MESHESHA Atsushi TSUNEKAWA Mitsuru TSUBO Nigussie HAREGEWEYN arid land Research Center Tottori University Department of land Resources management and Environmental Protection Mekelle University

Most of the lowland in the central rift valley of Ethiopia is arid or semiarid and in degradation,with frequent occurrence of *** erosion by water during the rainy season is a serious problem in the region,leading to declining agricultural production,decreased food security,and a sedimentation risk for water ***,there has been no systematic study of this problem or of possible management *** meet this need,we analyzed soil erosion rates from 1973 to 2006, identified erosion hotspots,and proposed possible soil conservation *** assessed the soil loss dynamicity using the universal soil-loss equation and geographical information system software, considering the land use change at the following three periods:1973,1985 and *** characterized the watershed in terms of the erosion severity,topography,and land use to identify hotspots and proposed,modeled,and evaluated various watershed management scenarios to mitigate the *** erosion increased markedly from 1973 to 2006,with annual rates of 31,38,and 56 t ha"1 in 1973,1985,and 2006,respectively,as a result of vegetation degradation and particularly the conversion of thousands of hectares of forest or woodland into *** observed soil erosion rates are far from the tolerable rate of soil loss of the country and hence require urgent soil conservation interventions,especially in the hotspot *** proposed eight scenarios for reducing soil losses and evaluated their *** degraded land（using exclosures and planted vegetation） and installing stone erosion-control structures（stone bund） in cropland reduced the total soil loss by 12.6%and 63.8%,*** hotspot areas with annual soil loss of more than 20 t ha;by integrated management（erosion-control structures and exclosures） was the most effective approach,reducing soil loss by 87.8%.

关键词： Environmental rehabilitation Ethiopia land degradation Soil conservation Soil erosion USLE model

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Interaction between Adjacent Lightning Discharges in Clouds

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Advances in Atmospheric Sciences 2013年第4期30卷 1106-1116页

作者：王彦辉张广庶张彤李亚珺武斌张廷龙 Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Using a 3D lightning radiation source locating system （LLS）, three pairs of associated lightning discharges （two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms） were observed, and the interaction between associated lightning discharges was analyzed. All these three pairs of associated lightning discharges were found to involve three or more charge regions （the ground was considered as a special charge region）. Moreover, at least one charge region involved two lightning discharges per pair of associated lightning discharges. Identified fl＇om electric field changes, the subsequent lightning discharges were suppressed by the prior lightning discharges. However, it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge. The third case provided evidence of this possibility. Together, the results suggested that, if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions, lightning accidents on the ground could be greatly reduced, on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable.

关键词： associated lightning inverted-polarity intracloud discharge charge region electrical structure

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Experimental demonstration of the coupling effect of vertical velocity on latent heat flux

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Science China Earth Sciences 2013年第4期56卷 684-692页

作者： CHEN JinBei HU YinQiao Lü ShiHua YU Ye Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and arid Regions Environment and Engineering Institute Chinese Academy of Sciences

According to the cross coupling theorem of atmospheric turbulence, latent heat flux comprises two components, a vertical humidity gradient flux and a coupling flux of vertical velocity. In this paper, observational data are employed to demonstrate and analyze the coupling effect of vertical velocity on latent heat flux. The results highlight the presence of a coupling zero-effect height. When the observational level exceeds or underlies the coupling zero-effect height, the coupling effect suppresses or enhances the latent heat flux, respectively. Above the heterogeneous terrain in the experimental region, the overall difference between the estimated and the observed latent heat fluxes decreases from 27% to 2% (for ascending flow) and from 47% to 28% (for descending flow), after compensating for gradient flux. The coupling theorem of atmospheric turbulence is well validated by our analysis, supporting a role for experimental datasets in unraveling the mysteries of atmospheric turbulence.

关键词： atmospheric surface layer (ASL) turbulent transport latent heat flux vertical velocity cross-coupling

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Connection Between Atmospheric Latent Energy and Energy Fluxes Simulated by Nine CMIP5 Models

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Journal of Meteorological Research 2015年第3期29卷 412-431页

作者：韩博吕世华李瑞青奥银焕陈昊高艳红马迪 Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

The atmospheric latent energy and incoming energy fluxes of the atmosphere are analyzed here based on the historical simulations of nine coupled models from the Coupled Model Intercomparison Project Phase 5 （CMIP5） and two reanalysis datasets. The globally averaged atmospheric latent energy is found to be highly correlated with several types of energy flux, particularly the surface latent heat flux, atmosphere absorbed solar radiation flux, and surface net radiation flux. On the basis of these connections, a hydrological cycle controlled feedback （HCCF） is hypothesized. Through this feedback, the atmosphere absorbed solar radiation is enhanced and causes intensification of the surface latent heat flux when the atmospheric latent energy is abnormally strong. The representativeness of the HCCF during different periods and over different latitudinal zones is also discussed. Although such a feedback cannot be confirmed by reanalysis, it proves to be a common mechanism for all the models studied.

关键词： atmospheric latent energy CMIP5 hydrological cycle climate feedback

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Effect of traffic restriction on atmospheric particle concentrations and their size distributions in urban Lanzhou, Northwestern China

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Journal of Environmental Sciences 2014年第2期26卷 362-370页

作者： Suping Zhao Ye Yu Na Liu Jianjun He Jinbei Chen Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold & Arid Regions Environmental & Engineering Research Institute Chinese Academy of Sciences University of Chinese Academy of Sciences

During the 2012 Lanzhou International Marathon, the local government made a significant effort to improve traffic conditions and air quality by implementing traffic restriction measures. To evaluate the direct effect of these measures on urban air quality, especially particle concentrations and their size distributions, atmospheric particle size distributions （0.5-20μm） obtained using an aerodynamic particle sizer （model 3321, TSI, USA） in June 2012 were analyzed. It was found that the particle number, surface area and volume concentrations for size range 0.5-10 μm were （15.0±2.1） cm-3, （11.8±2.6） μm2/cm3 and （1.9±0.6） μm2/cm3, respectively, on the traffic-restricted day （Sunday）, which is 63.2%, 53.0% and 47.2% lower than those on a normal Sunday. For number and surface area concentrations, the most affected size range was 0.5-0.7 and 0.5-0.8 μm, respectively, while for volume concentration, the most affected size ranges were 0.5-0.8, 1.7-2.0 and 5.0-5.4 μm. Number and volume concentrations of particles in size range 0.5-1.0μm correlated well with the number of non-CNG （Compressed Natural Gas） powered vehicles, while their correlation with the number of CNG-powered vehicles was very low, suggesting that reasonable urban traffic controls along with vehicle technology improvements could play an important role in improving urban air quality.

关键词： traffic restriction particle concentration size distribution urban air quality

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Response of Atmospheric Energy to Historical Climate Change in CMIP5

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Journal of Meteorological Research 2015年第1期29卷 93-105页

作者：韩博吕世华高艳红奥银换李瑞青 Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

Three forms of atmospheric energy, i.e., internal, potential, and latent, are analyzed based on the historical simulations of 32 Coupled Model Intercomparison Project Phase 5（CMIP5） models and two reanalysis datasets（NCEP/NCAR and ERA-40）. The spatial pattern of climatological mean atmospheric energy is well reproduced by all CMIP5 models. The variation of globally averaged atmospheric energy is similar to that of surface air temperature（SAT） for most models. The atmospheric energy from both simulation and reanalysis decreases following the volcanic eruption in low-latitude zones. Generally, the climatological mean of simulated atmospheric energy from most models is close to that obtained from NCEP/NCAR, while the simulated atmospheric energy trend is close to that obtained from ERA-40. Under a certain variation of SAT, the simulated global latent energy has the largest increase ratio, and the increase ratio of potential energy is the smallest.

关键词： atmospheric energy CMIP5 historical climate change

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A Diagnostic Analysis on the Effect of the Residual Layer in Convective Boundary Layer Development near Mongolia Using 20th Century Reanalysis Data

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Advances in Atmospheric Sciences 2015年第6期32卷 807-820页

作者： HAN Bo ZHAO Cailing L Shihua WANG Xin Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

Although the residual layer has already been noted in the classical diurnal cycle of the atmospheric boundary layer, its effect on the development of the convective boundary layer has not been well studied. In this study, based on 3-hourly 20th century reanalysis data, the residual layer is considered as a common layer capping the convective boundary layer. It is identified dally by investigating the development of the convective boundary layer. The region of interest is bounded by （30^-60~N, 80^-120~E）, where a residual layer deeper than 2000 m has been reported using radiosondes. The lapse rate and wind shear within the residual layer are compared with the surface sensible heat flux by investigating their climatological means, interannual variations and daily variations. The lapse rate of the residual layer and the convective boundary layer depth correspond well in their seasonal variations and climatological mean patterns. On the interannual scale, the correlation coefficient between their regional averaged （40°-50°N, 90°-110°E） variations is higher than that between the surface sensible heat flux and convective boundary layer depth. On the daily scale, the correlation between the lapse rate and the convective boundary layer depth in most months is still statistically significant during 1970-2012. Therefore, we suggest that the existence of a deep neutral residual layer is crucial to the formation of a deep convective boundary layer near the Mongolian regions.

关键词： convective boundary layer residual layer lapse rate surface sensible heat flux wind shear

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Responses of microbial activities and soil physical-chemical properties to the successional process of biological soil crusts in the Gurbantunggut Desert,Xinjiang

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Journal of arid land 2015年第1期7卷 101-109页

作者： BingChang ZHANG XiaoBing ZHOU YuanMing ZHANG Key Laboratory of Biogeography and Bioresources in arid land Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences

Biological soil crusts （BSCs） are capable of modifying nutrient availability to favor the establishment of biogeochemical cycles. Microbial activities serve as critical roles for both carbon and nutrient transformation in BSCs. However, little is known about microbial activities and physical-chemical properties of BSCs in the Gurbantunggut Desert, Xinjiang, China. In the present research, a sampling line with 1-m wide and 20-m long was set up in each of five typical interdune areas selected randomly in the Gurbantunggut Desert. Within each sampling line, samples of bare sand sheet, algal crusts, lichen crusts and moss crusts were randomly collected at the depth of 0-2 cm. Varia- tions of microalgal biomass, microbial biomass, enzyme activities and soil physical-chemical properties in different succession of BSCs were analyzed. The relationships between microalgal biomass, microbial biomass, enzymatic activities and soil physical-chemical properties were explored by stepwise regression. Our results indicate that micro- algal biomass, microbial biomass and most of enzyme activities increased as the BSCs developed and their highest values occurred in lichen or moss crusts. Except for total K, the contents of most soil nutrients （organic C, total N, total P, available N, available P and available K） were the lowest in the bare sand sheet and significantly increased with the BSCs development, reaching their highest values in moss crusts. However, pH values significantly decreased as the BSCs developed. Significant and positive correlations were observed between chlorophyll a and microbial biomass C. Total P and N were positively associated with chlorophyll a and microbial biomass C, whereas there was a significant and negative correlation between microbial biomass and available P. The growth of cyanobacteria and microorganism contributed C and N in the soil, which offered substrates for enzyme activities thus increasing enzyme activities. Probably, improvement in enzyme

关键词： chlorophyll a microbial biomass C soil enzyme physical-chemical properties biological soil crusts

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Morphological and physiological responses to drought stress of carob trees in Mediterranean ecosystems

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Journal of arid land 2023年第5期15卷 562-577页

作者： Khouloud ZAGOUB Khouloud KRICHEN Mohamed CHAIEB Lobna F MNIF Laboratory of Ecosystems and Biodiversity in arid land of Tunisia Faculty of SciencesUniversity of SfaxSfax 3000Tunisia

The greatest failure rate of reforestation programs is basically related to water deficit,especially at the seedling ***,the main objective of this work is to investigate the responses of three accessions of carob trees(Ceratonia siliqua L.)with 2-year-old from different climate regions to drought generated by four water treatments:Tc(250 mm),T1(180 mm),T2(100 mm),and T3(50 mm).The first accession(A1)comes from the protected national park of Ichkeul in northern *** zone belongs to the bioclimatic sub-humid *** second accession(A2)comes from Melloulech,located in the center-east of Tunisia,belonging to the bioclimatic semi-arid *** third accession(A3)comes from the mountain of Matmata,located in the south of Tunisia,belonging to the bioclimatic hyper-arid *** experiment was undertaken in a *** exchange indices(net photosynthesis(A),stomatal conductance(gs),transpiration rate(E),and internal CO_(2) concentration(Ci))were ***(Ψpd)and midday(Ψmd)leaf water potentials,relative soil water content(SWC),and morphological parameters(plant height(H),number of leaves(NL),number of leaflets(Nl),and number of branches(NB))were *** results showed that significant differences(P<0.001)were found between physiological and morphological parameters of each *** highest growth potential was recorded for Tc treatment in both accessions A1 and *** decreases in gs,E,Ci,and SWC were recorded with the increases in water stress applied from treatment T1 to *** and significant correlations were found between SWC andΨpd for all studied accessions.Ψpd andΨmd decreased as water stress increased,ranging from–0.96 to–1.50 MPa at sunrise and from–1.94 to–2.83 MPa at midday,respectively,under control and T3 *** accessions responded to drought through exhibiting significant changes in their physiological and morphological *** accessions A1 and A2 showed greater drought tol

关键词： Ceratonia siliqua L. water stress soil moisture stomatal conductance predawn leaf water potential minimum water potential

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Measuring the value of water quality improvements in Lake Tai, China

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第9期12卷 710-719页

作者： Wei-wen ZHANG Department of land management Zhejiang University Hangzhou 310029 China

Despite widespread concerns and elevated policy debates, little is known about the Chinese public＇s perceptions of water pollution and willingness to cooperate with government policies. Based on survey data, this study examined Lake Tai resident perception of water pollution, willingness to pay （WTP） for water quality improvements, and its influencing factors. Contingent valuation （CV） results showed that respondents would prefer to pay 141 CNY per household a year, approximately 0.70% of their annual per capita disposable income, as an environmental fee to improve water quality in Lake Yai. Aggregate WTP for all five lakeside cities of Lake Tai was estimated at about 3.8 billion CNY, without discounts, in the next ten years. WTP was found to increase with income and female respondents were willing to pay more than males. Those respondents who were dissatisfied with water quality were more likely to pay more. The usage of Lake Tai did not strongly affect WTE

关键词： Water quality Willingness to pay (WTP) Contingent valuation (CV) Lake Tai

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