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15 May 2020, Volume 37 Issue 3 Previous Issue    Next Issue

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Hydrogeochemical processes of groundwater formation in the Kashgar River Basin,Xinjiang 2020, 37 (3):  541.  doi: 10.13866/j.azr.2020.03.01 Abstract ( 1167 )   PDF (1793KB) ( 590 )   The formation of groundwater was mainly affected by leaching, evaporation, cation exchange, and mixing in the Kashgar River Basin. The dissolution of gypsum, halite, and fluorite minerals provided important sources of SO42-, Na+, Cl-, and F- to groundwater. Ca2+ and Mg2+ were mainly derived from the dissolution of minerals such as gypsum, feldspar, calcite, and dolomite. Gibbs diagrams show that unconfined groundwater was mainly affected by rock weathering and evaporationconcentration, whereas confined groundwater was predominantly affected by rock weathering in the northern part of the Kezilesu River groundwater system. Unconfined groundwater was mainly affected by evaporationconcentration, while shallow confined water was affected by rock weathering in the Gaizi River groundwater system in the southern part. Cation exchange was stronger in the Kezilesu River groundwater system in the northern part than in the Gaizi River groundwater system in the southern part. In general, cation exchange gradually increased with aquifer depth downward. Mixed action occurred both between the surface and groundwater, and also among different aquifers. References | Related Articles | Metrics

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Preliminary study on the relationship between vegetation and groundwater depth in the lower reaches of the Keriya River WANG Yamei, ZHANG Qingqing, LI Li, ZHAO Xinfeng 2020, 37 (3):  562.  Abstract ( 902 )   PDF (1515KB) ( 395 )   In 2018,the lower part of the Keriya River was selected as the monitoring section for the research target area.Two monitoring belts were set up,and a sample belt along the longitudinal direction of the river was selected,with a total of 11 monitoring stations.Three typical sections of riverine vegetation were selected at different distances from the river,making a total of eight monitoring points,to obtain information on the growth of the arbor shrub vegetation community and the groundwater depth of each section.Through the analysis of the status of vegetation growth and community distribution in the study area and discussion of the relationship between vegetation growth and groundwater depth,it is found that in the direction of the river,the groundwater level affects the distribution of plant communities.The groundwater depth of the monitoring sections 1-6 is shallow,and the vegetation is dominated by Phragmites australis.The depth of groundwater in sections 7-11 is decreasing,and the vegetation is dominated by Populus euphratica.Within 500 m of the river channel,the vegetation coverage in the desert direction is sparser,and the depth of the groundwater is deeper.In addition,the growth indicators are significantly different at 150,200,300,400,and 500 m (P <0.01).We found that different plants have different requirements for groundwater depth: Algagi sparsifolia,Glycyrrhiza uralensis,and other shallowrooted plants were more likely to grow where there is a shallow water table,and deeprooted plants,such as Populus euphratica and Tamarix spp.,were more dominant where there was a deep water table.In the deeper (7-11) and shallower (1-6) sections of the water table,the average height of the plants was 100.50 and 149.38 cm,respectively,and the latter was 48.64% higher than the former. References | Related Articles | Metrics

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Study on the correlation between soil moisture and temperature of different land uses in the loess area during a freezing-thawing period WU Qinqin, MO Shuhong, CHENG Shengdong, LI Peng, LI Zhanbin 2020, 37 (3):  627.  doi: 10.13866/j.azr.2020.03.10 Abstract ( 834 )   PDF (2175KB) ( 449 )   To study the changes in soil moisture and temperature during a freezing-thawing period ,the space-time change law of soil moisture and temperature of different soil depth layers were analyzed by monitoring the soil moisture and temperature data of different land use runoff plots in the field. The relationship between soil moisture and temperature in the study area was then clarified. The results showed that the variation degree of the 20 cm soil layer in sloped farmland was the largest,while the strongest active layers in the grassland and woodland were 30 cm and 10 cm,respectively. The 20 cm soil layer in the sloped farmland had the largest dispersion of water content,while the active layers in grassland and forestland were 30 cm and 10 cm,respectively. The grassland first entered the freezing period and the thawing period,and freeze and melt time lags layer by layer,and the soil moisture content and temperature of the three land types followed quadratic functions. The hydrothermal relationship of the soil in forestland was the strongest,which is more conducive to the soil water-heat retention in the loess area. This study provides a scientific basis for the research of soil moisture on vegetation restoration and the protection of the environment from construction in the loess area. References | Related Articles | Metrics

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Analysis of climate change in the Selin Co Basin,Tibetan-Plateau,from 1979 to 2017 WANG Kunxin, ZHANGYinsheng, ZHANG Teng, YU Kunlun, GUO Yanhong, MA Ning 2020, 37 (3):  652.  doi: 10.13866/j.azr.2020.03.13 Abstract ( 1091 )   PDF (2488KB) ( 680 )   In this study,data from the China meteorological forcing dataset (CMFD) and Global Land Data Assimilation System (GLDAS),including air temperature (2m),precipitation,specific humidity,wind speed (10m) and solar radiation,were used to study the modern climate characteristics of the Selin Co Basin,as well as its spatial-temporal variations throughout 39 years from 1979 to 2017 using linear tendency estimation,the Mann-Kendall mutation test,five-year moving average,and cumulative anomaly methods. Results showed that the multi-year annual average temperature,specific humidity,solar radiation,and wind speed were -1.8℃,3.2g·kg-1,236.2 W·m-2,and 3.7m·s-1,respectively. The multi-year average annual precipitation was 389.4 mm. For all years,monthly average temperatures were above 0℃ from May to September and generally lower than 0℃ in the other months. Between 1979 and 2017,the annual average temperature in the Selin Co Basin increased significantly at a rate of 0.049℃·a-1. 80% of the annual precipitation occurred between June and September. The annual average precipitation in the basin for the same period also increased significantly at a rate of 4.65mm·a-1. Together,increased temperature and precipitation demonstrates an obvious changing climate characterized by a tendency toward warmer and wetter conditions during the last 20 years. During the same period,wind speed showed an increasing trend in the southern region and a decreasing trend in northern region,with the largest rate of decrease occurring in northeast of the basin. From east to west,the multi-year annual average solar radiation gradually increased. Solar radiation showed a significant decrease at a rate of -0.29 W·m-2·a-1 throughout the last 39 years,especially from the mid-1980s until the mid-2000s. Moreover,while specific humidity did not show a significant change,it exhibited a significant decreasing trend since 2006. Results of this study are indicative for delineating the mechanism of lake expansion,the response of ecosystems to climate change,and phenological changes. References | Related Articles | Metrics

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Consistency and comparison among remote sensing drought indices and SMAP soil moisture in Kazakhstan SUN Bo, QIAN Jing, CHEN Xi, XING Xiuwei, ZHOU Qiming 2020, 37 (3):  663.  doi: 10.13866/j.azr.2020.03.14 Abstract ( 806 )   PDF (1379KB) ( 291 )   In order to evaluate the applicability of remote sensing drought indices for agricultural drought monitoring in the arid zone of Central Asia,several typical indices (i.e.,AVI,VHI,and VSWI) from current global drought monitoring systems were assessed using active and passive microwave soil moisture data (SMAP).Data from late June,the middle and late period in the plant growing season,were utilized for this experiment.According to datasets for existing land use and land cover,more than 2650 samples fully covered by vegetation were chosen.Correlations between remote sensing drought indices and soil moisture were examined using the Pearson correlation coefficient (r) and Kendall rank correlation coefficient (τ) .Resultes show that AVI and soil moisture are not significantly correlated.However,VHI and VSWI are significantly positively correlated with soil moisture at two layers,including the surface layer (0-10cm) and the root zone layer (0-100cm).By comparison,VSWI exhibits a strong correlation with soil moisture at root zone level (r>0.6),which also shows a good response to drought conditions in the middle and late stages of the growing season in Kazakhstan.For determining drought grade,VHI shows a weak positive correlation with soil moisture. References | Related Articles | Metrics

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Effect of habitat fragmentation on the population genetic structure of Malus sieversii ZHANG Hongxiang, ZHENG Tianyong 2020, 37 (3):  715.  doi: 10.13866/j.azr.2020.03.20 Abstract ( 588 )   PDF (913KB) ( 271 )   Habitat fragmentation has complex genetic effects on plant populations. Malus sieversii exists in a few small fragmented subpopulations within a geographical population. For this study,we chose the geographical population of Gongliu,which has a high level of genetic diversity. The genotypes of 101 individuals from five subpopulations were marked using SSR loci. By analyzing the difference in genetic diversity and the genetic relationships among these five subpopulations,we aimed to investigate the effect of habitat fragmentation on the population genetic structure of [WTBX]Malus sieversii. The results showed that different levels of genetic diversity existed among these five subpopulations,in which a high level of genetic diversity was shown in marginal subpopulations of Saha and Xiaomoheer 2. These five subpopulations were clustered into two genetic lineages,which displayed an eastwest split due to the effect of geographical isolation. It is proposed that these marginal subpopulations and different genetic lineages should be considered during the processing of germplasm resource protection and the core collection of germplasm for M.sieversii. References | Related Articles | Metrics

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Desertification and its driving factors in the Ordos Plateau,from 1986 to 2015 2020, 37 (3):  749.  doi: 10.13866/j.azr.2020.03.24 Abstract ( 813 )   PDF (1567KB) ( 291 )   The Ordos Plateau is a typical area undergoing desertification in China.The desert areas of the Ordos Plateau between 1986 and 2015 were derived from remote sensing analysis and relationships between desertification area and potential driving factors,including climate and human activity,were analyzed using multivariate linear stepwise regression analysis.The results show that: (1) The year 2000 was the turning point at which the desertification of the Ordos Plateau first increased and then decreased.From 1986 to 2000,the Ordos Plateau showed general desertification expansion,especially in the west and south; during 2001-2015,the desertification area gradually decreased,with reduction mostly occurring in the eastern and southern parts of the plateau.After 2012,desert areas increasingly developed in the western part of the plateau.(2) Among the driving factors influencing the desertification of the Ordos Plateau,precipitation and population are the most significant,with precipitation being most closely related to desertification.Other factors show no significant relation to desertification.From 1986 to 2015,increased precipitation contributed to the reversal of desertification,while the rise of rural population accelerated the desertification process. References | Related Articles | Metrics

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Response relationship between micro-relief variation and slope erosion under sand-covered conditions 2020, 37 (3):  757.  doi: 10.13866/j.azr.2020.03.25 Abstract ( 599 )   PDF (1595KB) ( 368 )   The development of the slope of micro-relief reflects the intensity and process of erosion. To quantitatively study the response between the characteristics of micro-relief variation and the amount of erosion,three consecutive rainfall tests with simulated precipitation of 1.5 mm·min-1 were conducted,and the spatial variation characteristics of micro-relief and soil erosion were analyzed using 3-D laser scanner technology. The relationship between the amplitude of micro-relief and erosion was well fitted. The results showed that average sediment concentrations on the slope were reduced as the number of rainfall events increased. The lengths of the main sandpredicted area on the sand covered slope were about three times that of the loess slope,and peaks of the amount of erosion of the slope were mostly found at the position of 4-6 m on the slope,but the peaks of erosion on the loess slope were found in the position of 3-4 m. As the rainfall simulation progressed,the micro-relief factors of the loess slope increased significantly (P<0.05),and the micro-relief factors of the sand-covered slope increased,but not significantly (P>0.05). The study found that the micro-relief factors with the strongest erosion response to the loess slope and the sand-covered slope were surface incision and surface roughness,respectively. The response relationship between micro-relief variation and erosion of the loess slope was stronger than for the sand-covered slope,so the sand-covered slope should be examined for other sensitive indicators to optimize the equation. This study provides reference information for determining the erosion mechanism of wind water erosion across the region. References | Related Articles | Metrics