Authority in Charge: Chinese Academy of Sciences
Sponsored by: Xinjiang Institute of Ecology and
Soil Science Society of China
Editor in Chief: Lei Jiaqiang
Started in: 1984, Bimonthly
CN: CN 65-1095/X
ISSN: ISSN 1001-4675
Domestic Postal Code: 58-37
Foreign Postal Code: BM4927
Website: http://azr.xjegi.com/
15 May 2022, Volume 39 Issue 3
 Changes of pollen taxa diversity in the arid Central Asia under the Holocene Westerlies Mode: A case study of the Altai Mountains ZHANG Dongliang 2022, 39 (3):  667-675.  doi: 10.13866/j.azr.2022.03.01 Abstract ( 146 )   HTML ( 24 )   PDF (7948KB) ( 75 )   Modern climate change poses a huge threat to plants in the arid Central Asia. Due to the short instrumental interval, we are unable to better understand the long time-scale relationship between plant diversities and climate change in this region. However, pollen records in the geological archives provide us an opportunity to understand the existence, distribution and diversity of plants in the past. In this study, we selected three pollen sequences from different elevations (Halasazi Peat, Narenxia Peat and Kanas Lake) in the Altai Mountains to investigate the characteristics of plant diversities and their response patterns to Holocene climate change. The results revealed that the changes of pollen taxa diversity in the Altai Mountains showed a unique pattern. As the climate was warming in the early Holocene, the upper forest limits began to migrate upward, leading to an increase in pollen taxa diversity at high elevations. In the middle Holocene, the climate was warm and wet, and the upward and downward migration of the upper and lower forest limits resulted in higher diversities at high and low elevations, but the lower diversities in the taiga-dominated forest belt mainly resulted from a decreasing species evenness. In the late Holocene, the climate became cooler and wetter, and the upper forest limits moved downward, leading to a significant increase in diversities at middle elevations. The largest changes of plant diversities were observed in the forest belt during the Holocene, which means this belt is the most sensitive and vulnerable area for climate response. This study not only helps us understand the response model of mountain vegetation belt to Holocene climate change, and also provides key evidence for exploring the history of mountain vegetation migration in the arid Central Asia.
 Temporal reconstruction of alpine glacier surface elevation variation in Central Asia DU Weibing,ZHANG Shiqiong,LI Junli,BAO Anming,WANG Shuangting,SHI Ningke,XU Linjuan,GAO Xin,MA Dandan,ZHENG Yanchao 2022, 39 (3):  676-683.  doi: 10.13866/j.azr.2022.03.02 Abstract ( 91 )   HTML ( 13 )   PDF (6799KB) ( 106 )   The topography of the alpine glacier area in Central Asia is complex. Satellite laser altimetry technology can be used to monitor large-scale glacier surface elevation change. This study used ICESat laser altimetry data from 2003 to 2009, and shuttle radar topography mission (SRTM) elevation data and Randolph glacier inventory (RGI) 6.0 cataloging data for 2000 to monitor the surface elevation change of alpine glaciers in Central Asia. The glacial region of Central Asia is divided into three regions according to geographical form. First, the data were tested for normality to eliminate error. When a normal distribution was not observed, outlier values from the standard deviation of the linear regression were selected as abnormal. Point cloud denoising and its accuracy optimization algorithm and a multi-scale analysis model of temporal and spatial variation in surface elevation in the glacier area were established. A cubic polynomial model was used to fit the glacier surface elevation data for different scales across the whole area and sub regions of the high Asian mountains. A time series reconstruction of changes in alpine glacier surface elevation in Central Asia was carried out based on the data for each region from 2003. Temporal changes in glacier surface elevation from 2003 to 2009 were analyzed. The results showed that the average elevation for the whole region decreased, with clear regional differences. From 2003 to 2009, the surface elevation of high Asian glaciers decreased by 9.59 ± 1.89 m. The glacier surface elevation in Areas I (i.e., Tibet and southern Qinghai), II (i.e., Xinjiang, Northern Qinghai, and some parts of Gansu), and III (i.e., outside China and some countries in Central Asia) decreased by 6.51 ± 2.9 m, 7.87 ± 5.03 m, and 9.81 ± 5.1 m, respectively. The glacier surface elevation increased from 2004 to 2005. Area I showed the slowest decline in glacier elevation, followed by Area II; Area III showed the fastest decline. This research method has universal application potential for monitoring point cloud elevation in glacier areas. The model evaluation parameter (R2) was >0.98, indicating that the cubic polynomial relationship between ICESat data and SRTM elevation data showed strong universality in this area. However, this will make the point cloud data more sparse, and the model is highly dependent on the benchmark DEM.
 Assessment of CRU, ERA5, CMFD grid precipitation data for the Tibetan Plateau from 1979 to 2017 WEN Tingting,GUO Yingxiang,DONG Shaorui,DONG Yuanzhen,LAI Xiaoling 2022, 39 (3):  684-697.  doi: 10.13866/j.azr.2022.03.03 Abstract ( 164 )   HTML ( 12 )   PDF (6996KB) ( 268 )   In this paper, CRU, ERA5, and CMFD precipitation data for the Qinghai-Xizang Plateau were evaluated on annual and seasonal scales and compared with observed precipitation data from 131 weather stations. (1) The three data types all showed a strong ability to describe total annual precipitation on the plateau, and their correlation coefficients with the observed values were all >0.9. Results from all three models were generally higher than observed precipitation. CRU and CMFD results were closest to observed values in spring, while CMFD results were closest to the observed values in summer and fall; all three models showed the weakest correlations with observed values for winter precipitation. (2) In terms of precipitation distribution, CMFD data had the best ability to simulate plateau precipitation annually, and in spring, summer, and winter. The models showed regional differences in describing fall precipitation. CRU and CMFD results were closest to observed values on the western plateau. (3) Plateau precipitation increased during spring, summer, and fall, especially in the summer, and decreased in the winter. (4) The annual and seasonal variation (spring, summer, and fall) in the CRU data was consistent with that of the observed data, and the winter precipitation results from ERA5 were consistent with observed values. (5) The deviation between CMFD results and observed annual and seasonal precipitation was the smallest. (6) Time series analysis showed that CMFD annual, spring, summer, and fall precipitation results were closest to the observed values, followed by CRU. CMFD winter precipitation results were closest to the observed values, but the correlation coefficient failed the significance test of 95%.
 Study on spatio-temporal dynamics and driving factors of NPP in Central Asian grassland ZHANG Yunxin,HAO Haichao,FAN Lianlian,LI Yaoming,ZHANG Renping,LI Kaihui 2022, 39 (3):  698-707.  doi: 10.13866/j.azr.2022.03.04 Abstract ( 113 )   HTML ( 8 )   PDF (9614KB) ( 82 )   Based on the CASA and Miami models, the net primary productivity (NPP) of five Central Asian countries (Kazakhstan, Tajikistan, Kyrgyzstan, Turkmenistan, and Uzbekistan) was calculated in this study. The purpose was to explore the Spatio-temporal dynamics and driving factors of NPP in Central Asian grassland from 2001 to 2019. The results showed that the average ANPP of grassland in Central Asia from 2001 to 2019 was 118.9 g C·m-2·a-1. On the spatial scale, the ANPP of grassland in the plain area increased gradually from south to north with increasing latitude. In contrast, the ANPP of grassland from plain to mountain grassland increased with increasing altitude. On the temporal scale, the overall growth trend of ANPP was not significant, and the future change trend of grassland ANPP in approximately 60% of the region was opposite to that of the past. The trend was not significant in the region of Central Asia with increased grassland ANPP where human activities are dominant and with decreased grassland ANPP, with climate change as the main driving force. A significant positive correlation existed between ANPP and precipitation accounting for 67.8%, with no significant relationship between temperature and the change of ANPP in Central Asian grassland. Therefore, precipitation is the main climatic factor affecting the change of ANPP in Central Asian grassland.
 Changing precipitation characteristics in the Yellow River Basin in the last 60 years and tendency prediction for next 30 years WANG Chenghai,YANG Jintao,YANG Kai,ZHANG Feimin,ZHANG Shengning,LI Kechen,YANG Yi 2022, 39 (3):  708-722.  doi: 10.13866/j.azr.2022.03.05 Abstract ( 118 )   HTML ( 6 )   PDF (7846KB) ( 94 )   The climate of the Yellow River Basin has distinctly changed in the past 60 years, which significantly impacts its surface hydrological and ecological processes. In this study, the spatial and temporal characteristics of precipitation in the Yellow River Basin in the past 60 years (1961-2018) were analyzed using in-situ precipitation observations in this basin. Future precipitation trends for the next 30 years (2018-2047) in the Yellow River Basin were projected using outputs from the SSP245 scenario in the CMIP6 model and statistical methods. Results show that there are significant annual, inter-annual, and inter-decadal variations in precipitation in the Yellow River Basin, with a significant oscillation cycle of 2-4 years. For the whole basin, annual and seasonal precipitation is basically isotropic at an inter-annual scale but significant areas of inter-annual variability anomalies are different. Spatial anomalies of precipitation are opposite in the cold season (winter-spring) and the warm season (summer-autumn), with a decrease in precipitation influenced by summer monsoon activity and an increase in precipitation influenced by the winter monsoon. There has been an increasing trend of 20.96 mm·(10a)-1 in annual precipitation in the Yellow River source area for the past 60 years, and expected annual precipitation will continue to increase at 11.53-17.62 mm·(10a)-1 over the next 30 years. Annual precipitation in the Hetao area of the Yellow River Basin has continued to increase in the past 60 years at a rate of 2.71 mm·(10a)-1, but the rate of future increase has slowed to approximately 0.52 mm·(10a)-1. In lower reaches of the Yellow River, a decreasing trend in precipitation in the past 60 years is presented and will continue to decrease at a rate of 5.46 mm·(10a)-1.
 Analysis of multi-scalar characteristics of dry and wet conditions in the Yellow River Basin based on SPEI GAO Bingli,GONG Jie,LI Yan,JIN Tiantian 2022, 39 (3):  723-733.  doi: 10.13866/j.azr.2022.03.06 Abstract ( 77 )   HTML ( 5 )   PDF (6615KB) ( 57 )   Based on daily data from 70 meteorological stations in the Yellow River Basin from 1960 to 2020, the Standardized Precipitation Evapotranspiration Index (SPEI) based on precipitation and potential evapotranspiration was calculated. Then, the evolution and persistence characteristics of dry-wet change of the Yellow River Basin from 1960 to 2020 were studied and their influence on meteorological factors was analyzed. Results showed the following: (1) There were differences in dry and wet grades and frequencies among the SPEI at different time scales and dry and wet levels were dominated by normal and light conditions. There was an insignificant wetness trend in summer and an insignificant dryness trend annually, and during spring, autumn, and winter from 1960 to 2020 in the Yellow River Basin. Geographically, the summer climate was mainly wet and 64.29% of meteorological stations showed an increased SPEI. The annual, spring, autumn, and winter climate in the Yellow River Basin was mainly dry and 51.43%, 62.86%, 64.29%, and 51.43% of meteorological stations showed a decrease SPEI, respectively. (2) For the different time scales of dry and wet events, 1970-1979 was a partial dry period, whereas 1960-1969 was a partial wet period, and the frequency of dry and wet events was as follows: autumn > summer > spring > winter. (3) From persistent characteristics of dry and wet events, the intensity of ongoing drought events increased and occurred mainly in autumn and winter, whereas the intensity of persistent wet events increased and occurred mainly in autumn. (4) A decreasing trend in the SPEI from 1960 to 2020 was mainly due to combined effects of a decrease of precipitation, average wind speed and relative humidity.
 Applicability of the LSTM and ARIMA model in drought prediction based on CEEMD: A case study of Xinjiang DING Yan,XU Dehe,CAO Lianhai,GUAN Xiangrong 2022, 39 (3):  734-744.  doi: 10.13866/j.azr.2022.03.07 Abstract ( 68 )   HTML ( 4 )   PDF (7895KB) ( 36 )   The frequent occurrence of droughts seriously affects normal agricultural production and economic development. Accurate prediction of drought occurrence is of great importance in reducing drought losses. Nevertheless, drought occurrences have not been well predicted. Drought indices can be used to quantitatively evaluate the intensity, duration, and influence range of drought. Thus, on the basis of daily precipitation data from 1960 to 2019 in the Xinjiang Uyghur Autonomous Region, the standardized precipitation index (SPI) at timescales of 1, 3, 6, 9, 12, and 24 months were calculated. Aiming for the nonlinear and nonstationary characteristics of SPI, a new drought prediction method was proposed combining the single model and the complementary ensemble empirical mode decomposition (CEEMD), which can process nonlinear and nonstationary signals. In this paper, the autoregressive integrated moving average (ARIMA) model, the long short-term memory (LSTM) network, the CEEMD-ARIMA combined model, and the CEEMD-LSTM combined model were constructed to predict a multiscale SPI. The validity of prediction models was determined using root mean square error, mean absolute error, and coefficient of determination (R2). Kriging interpolation was used to demonstrate the predicted results of the four models. The results revealed that the forecast accuracy of the four models increases with the increase of SPI timescales, and the highest accuracy is obtained at SPI24. CEEMD decomposition can effectively stabilize the time series. Drought prediction based on the CEEMD provides a stable premise for the single model. At each timescale, combined models obtain higher prediction accuracy than single models, which indicates that combined models are more suitable for drought prediction. The forecast accuracy of the four models in order from the lowest to highest accuracy is the LSTM model, followed by the ARIMA, CEEMD-LSTM, and CEEMD-ARIMA models (the maximum R2 values are 0.8882, 0.9103, 0.9403, and 0.9846, respectively). The CEEMD-ARIMA model shows the best ability to forecast SPI values. This study explored the applicability of four drought prediction models and provided a basis for meteorological disaster prevention and mitigation efforts.
 Analysis of change and causes of evaporation for the Shiyang River Basin during the past 60 years LI Xiaoqin,RAN Chen,ZHANG Xiaoxia,RAN Xinmin 2022, 39 (3):  745-753.  doi: 10.13866/j.azr.2022.03.08 Abstract ( 93 )   HTML ( 4 )   PDF (8572KB) ( 48 )   Evaporation is an essential component in hydrological processes, and understanding the change and causes of evaporation is of importance for sustainable management of water resources. Based on the four selected meteorological stations, Wushaoling, Yongchang, Wuwei and Minqin, of which ranged along the altitudinal gradient from 1958 to 2017, the study analysed the change of evaporation and its causes based on the modified PenPan model for the Shiyang River Basin. The results shown that (1) the spatially variation of evaporation can attribute to the altitude effects, namely the evaporation decreased with a rate of 38 mm for every 100 m elevation increase, and temporally change has the significant stage differentiation features, i.e. decreased in 1958-1970, whereas increased after 1970, that particularly obvious in the plain areas of low elevation but not in mountainous area; (2) there was a good agreement with the R2 greater than 0.85 between the observed evaporation and calculated by the modified PenPan model whether in daily or monthly time-scale, however, the wind speed function need amend further in order to obtain the robust performance; and (3) the yearly change of radiative component was relatively stable, but the aerodynamic component of evaporation increase fluctuated, of which was in consistent with the change of temperature and vapor pressure deficit, suggest that the rised temperature is the major reason for the increase of evaporation in Shiyang River Basin after 1970. The result means that the evaporation will increased under climate warming, it will impose more stress on the water resource sustainable management in the future.
 Precipitation gradient influence on daily greenhouse gas emission fluxes from a Qinghai Lake wetland YANG Ziwei,CHE Zihan,LIU Fumei,CHEN Kelong 2022, 39 (3):  754-766.  doi: 10.13866/j.azr.2022.03.09 Abstract ( 76 )   HTML ( 1 )   PDF (6795KB) ( 120 )   Moisture is the main limiting factor affecting the growth and development of alpine ecosystems. To explore effects of different water conditions on characteristics of greenhouse gas emissions from wetlands, wetlands at the source of the Wayan Mountain in Qinghai Lake Basin were selected. Box-gas chromatography monitored 24-hour greenhouse gas emission characteristics of wetlands and explored effects of control treatment (CK), +25% (precipitation increase 25% treatment), -25% (reduction in the daily change trend of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) under conditions of 25% rain treatment), +75% (precipitation increaseo of 75% treatment), and -75% (precipitation reduction of 75% treatment). The results showed that: (1) CO2 emission ranged from 47.52 to 123.71 mg·m-2·h-1, CH4 flux ranged from -8.50 to 6.74 µg·m-2·h-1, and N2O flux ranged from -15.82 to 6.90 µg·m-2·h-1. (2) The diurnal variation of CO2, CH4 and N2O in CK, +25% and +75% treatments showed emission status, and the diurnal variation of CO2 in -25% treatment showed emission status, while CH4 and N2O showed absorption status; The diurnal changes of CO2 and N2O under -75% treatment were emission state, while CH4 was absorption state, and there were significant differences among different precipitation treatments (P<0.05). (3) CO2 had a significant positive correlation with soil temperature (P<0.05) and a significant negative correlation with soil moisture (P<0.05); There was a significant negative correlation between CH4 and soil temperature (P<0.05) and between CH4 and soil moisture (P<0.05); There was a positive correlation between N2O and soil temperature (P<0.05), while there was a negative correlation between N2O and soil moisture in CK treatment and a positive correlation in rain reduction treatment (P<0.05), and there was no obvious regularity. (4) Small succession of plant communities occurred under different water treatments. The balance of soil moisture and temperature has a significant impact on the greenhouse gas emission flux in this area, and the imbalance should be avoided to lead to the increase of greenhouse gas emissions.
 Characteristics and causes of climate change in hail in occurrence Shaanxi Province MA Rongjun,LI Xiaofei,MAO Yanlin,XUE Yutong,WU Zhanhao 2022, 39 (3):  767-773.  doi: 10.13866/j.azr.2022.03.10 Abstract ( 143 )   HTML ( 6 )   PDF (5395KB) ( 100 )   Numerous studies have shown that the number of hailstorms in Shaanxi Province (northern China) has been significantly decreasing from the late 1990s to the present, but studies on the characteristics of hailstorm changes within more specific provincial regions are lacking. To investigate the hail occurrence patterns in Shaanxi Province and to better predict and prevent hail, this paper analyzes the characteristics of hail variability in Shaanxi Province on the basis of hail data recorded at 99 ground stations from 2000 to 2019 provided by the Meteorological Center of the Shaanxi Provincial Meteorological Bureau. For the analysis of different regions in the province, the stations were divided into three regions, namely northern Shaanxi (Yan’an and Yulin), central Guanzhou (Xi’an, Baoji, Xianyang, Tongchuan, and Weinan), and southern Shaanxi (Hanzhong, Ankang, and Shangluo) according to the administrative divisions of the cities where the stations are located. The climatic characteristics of hail in each region were analyzed separately. We found that the number of hailstorms in Shaanxi Province increases from south to north; a linear fit of elevation to the mean annual hailstorm number revealed a significantly positive correlation between elevation and mean annual hailstorm number at low elevations, with each 1 m increase in elevation within 1.5 km of elevation increasing the mean annual hailstorm number by 0.0007. Furthermore, hail occurrence in Shaanxi Province increases from south to north with seasonal differences; hailstorms in northern Shaanxi occur more frequently in the summer and less frequently in the winter. The region with the next-highest number of hailstorms is Guanzhong, and an average number of hailstorms occurs in southern Shaanxi. A 5 year sliding average of the interannual hail counts was fitted linearly, and results show a decreasing trend in the overall interannual hail counts in Shaanxi Province, with the fastest decline in northern Shaanxi, followed by Guanzhong; there was no significant interannual variation in southern Shaanxi. Using monthly averages of ERA5 parameters provided by the ECMWF and considering the physical mechanisms of the hail process, eight indicators were selected and fitted to the 5 year sliding average: (1) convective effective potential energy (CAPE); (2) the K-index; (3) 2 m temperature (i.e., air mass temperature 2 m from the ground); (4) 2 m dew point (i.e., air mass dew point temperature 2 m from the ground); (5) 0 ℃ layer height; (6) convective precipitation; (7) total precipitation; and (8) cloud base height. A linear fit was made to the hail counts; results show that CAPE played a dominant role in the interannual trend of hail in Shaanxi Province, and the K-index played a dominant role in the summer in northern Shaanxi and in the spring in Guanzhong. Furthermore, the 0 ℃ layer height played a dominant role in the trend of hail counts during the summer and autumn in Guanzhong and during the spring and summer in southern Shaanxi.
 An automatic method for delineating lake surfaces in Qaidam Basin using Landsat images WEN Guangchao,LI Xing,WU Bingjie,WANG Xiaohe,XIE Hongbo 2022, 39 (3):  774-786.  doi: 10.13866/j.azr.2022.03.11 Abstract ( 79 )   HTML ( 6 )   PDF (6305KB) ( 62 )   Lakes in the Qaidam Basin maintain regional ecological balance, supply production and domestic water consumption, and protect the ecological environment. These lakes have undergone a series of changes in response to enhanced regional climate change and human activities. To analyze characteristics of lake changes and investigate casual factors, an automatic method for lake surface delineation based on Landsat remote sensing images with a different series of sensors (the Lake Water Differential Model) was proposed by understanding TOA (top-of-atmosphere) reflectance differences between water and non-water surfaces in the Koruk Lake Basin. This model is applied to extract lake information at varying times or locations. Model performance is evaluated using overall accuracy, the Kappa coefficient, and user’s accuracy, and the derived lake surfaces were compared to those from the NDWI (Normalized Difference Water Index) and MNDWI (Modified Normalized Difference Water Index) methods. These results show the following: (1) target and non-target objects are distinguished by a TOA reflectance difference. (2) Based on a stable threshold, the Lake Water Differential Model can delineate lake surfaces. Compared with the NDWI, MNDWI, and other water body information extraction methods, the Lake Water Differential Model can more effectively suppress interference factors, such as surface rivers, ice, snow, shadows, swamps, and wetlands. In areas of model application, our proposed method can achieve a performance of 99.48% of the average OA, 99.66% of user accuracy, and 0.9877 of Kappa. (3) Input data of the model can be either TOA or Landsat (level-2) surface reflectance data. (4) The model is suitable for extracting lake water information in a large area of Qaidam Basin and provides technical support for the study of lake surface dynamics.
 Evaluation of groundwater resource sustainability based on GRACE and GLDAS in arid region of Northwest China RUAN Yongjian,WU Xiuqin 2022, 39 (3):  787-800.  doi: 10.13866/j.azr.2022.03.12 Abstract ( 72 )   HTML ( 3 )   PDF (4869KB) ( 63 )   The arid region of Northwest China is a groundwater-dependent ecosystem. Groundwater resources are a strategic support for developing the arid region in Northwest China. It is important to understand the significance of groundwater changes in real time to reveal change characteristics of groundwater and regional economic development. Previously, traditional groundwater monitoring research was artificial and expensive and large-scale and long-term analyses were difficult. Research based on satellite information also lacks quantitative evaluations of groundwater sustainability. To explore recent groundwater sustainability in arid areas of Northwest China, GRACE gravity satellite and GLDAS data were used to invert groundwater storage changes and determine trend changes for 200 months from April 2002 to September 2020 in arid areas of Northwest China. The groundwater drought index, which is based on GRACE, was calculated to obtain the groundwater drought situation in the arid region of Northwest China. Finally, the GGDI was further combined with the sustainability index to quantify the reliability, resilience, and vulnerability of groundwater to evaluate the recent groundwater sustainability in the arid region of Northwest China. Results show that from 2002 to 2020, groundwater reserves were greatly reduced in the arid area of Northwest China, and the drought degree of groundwater has deepened. The average reliability, resilience, and vulnerability of groundwater is 0.495, 0.470, and 0.404, respectively, and the regional groundwater sustainability index (SI) is 0.28, which indicates a low groundwater sustainability level. This study reveals a temporal and spatial distribution and the evolution trend of groundwater sustainability in arid regions of Northwest China, which provides theoretical and supporting data for the protection and management of regional groundwater resources.
 Combined weight method based on game theory for flood risk assessment in the Wuwei Region SU Guangquan,LYU Haishen,ZHU Yonghua,CHEN Tingxing,HUA Jiacheng 2022, 39 (3):  801-809.  doi: 10.13866/j.azr.2022.03.13 Abstract ( 71 )   HTML ( 2 )   PDF (3928KB) ( 43 )   Floods are the most frequent natural disasters in the world, and the Chinese region has shown the most significant increase in flood risk worldwide. Based on the frequency of flash floods in Wuwei City, Gansu Province, a flood risk assessment method combined with subjective and objective weights and based on game theory was adopted and GIS technology was applied. Seven indicators were selected to construct a flood risk assessment index system from three aspects: disaster dangers, disaster environment sensitivity, and suffering flexibility. Then, the risk zoning chart of flood disaster in Wuwei was drawn, which showed that the overall flood risk level of Wuwei City is low and flood risk shows a decreasing distribution characteristic from southwest to northeast. The results are in good agreement with historic flood event data in which the highest risk area accounts only for 4.94% of the total area, which is concentrated at the junction of Liangzhou District and Gulang County and southwest of Tianzhu County. The sum of the lowest risk area and the lower risk area accounts for 43.84% of the total area, which is concentrated in the eastern desert area of Minqin County. The main sources of flood risk vary among counties in Wuwei City. The risk of disaster-causing factors presents a belt-like distribution characteristic that decreases from southwest to northeast. The highest risk areas are distributed mainly in the Qilian Mountains of Tianzhu County, and the lowest risk areas are concentrated in lower reaches of the Shiyang River in the northeast. The distribution of the disaster environment sensitivity is relatively uniform except for the Qilian Mountains with higher stability. There are obvious differences in the vulnerability of disaster-bearing bodies, and the vulnerability at the junction of Liangzhou County and Gulang County is much higher than that of other regions. The entropy method and analytic hierarchy process are used for comparison with the game theory combination weighting method, which demonstrates that the combination weighting method of game theory can reduce the subjectivity of the single weighting method, improve the accuracy of the flood risk map, and provide valuable information for flood management.
 Spatiotemporal variations of stable hydrogen and oxygen isotopes in Xinjiang tap water XIA Yijie,WANG Shengjie,ZHANG Mingjun 2022, 39 (3):  810-819.  doi: 10.13866/j.azr.2022.03.14 Abstract ( 49 )   HTML ( 2 )   PDF (5404KB) ( 20 )   Stable hydrogen and oxygen isotopes are natural tracers reflecting the water cycle process, and tap water is an important domestic water source. The variation of stable hydrogen and oxygen isotopes in tap water is useful for tracing sources of domestic water supply and provides a reference for rational water resource management. The measured isotopic data of 352 tap water samples in Xinjiang were applied to analyze the spatiotemporal variation of stable hydrogen and oxygen isotopes as well as deuterium excess (d-excess; d = δ2H - 8δ18O) in tap water. The results show that the d-excess of the tap water line in Xinjiang is δ2H = 7.67δ18O + 10.54 (R2 = 0.92). The value of δ2H ranges from -105.57‰ to -37.82‰ on a monthly basis, and δ18O ranges from -14.48‰ to -6.67‰. The d-excess fluctuates from 1.89‰ to 24.38‰. The stable hydrogen and oxygen isotopes, as well as d-excess, exhibit seasonal variation in both northern and southern Xinjiang, and the seasonal difference in southern Xinjiang is greater than that in northern Xinjiang. The BW model is applied to map the stable hydrogen and oxygen isotopes in tap water. Tap water in southern Xinjiang presents higher isotopic values than northern Xinjiang, and water in the mountainous regions shows lower isotopic values than does water in the low-lying basins.
 Hydrogen-oxygen isotope characteristics of water bodies in the Xiangride-Qaidam River Basin and its influencing factors HE Qixin,CAO Guangchao,CAO Shengkui,CHENG Mengyuan,DIAO Erlong,GAO Siyuan,QIU Xunxun,ZHAO Meiliang,CHENG Guo 2022, 39 (3):  820-828.  doi: 10.13866/j.azr.2022.03.15 Abstract ( 58 )   HTML ( 2 )   PDF (3529KB) ( 34 )   In this paper, 59 sets of samples from different water bodies such as lake water, river water, groundwater, well water, and snow in the Xiangride-Qaidam River Basin were used to measure δ2H and δ18O of indoor samples; analyze their characteristics; and explore their influencing factors, deuterium excess parameter values, and river water variation along the river. Results show that (1) the hydrogen and oxygen isotope characteristics of the water bodies in the Xiangride-Delta River Basin are different. In addition, the enrichment of δ18O during water cycle is presented in the following order: lake water > ice > groundwater > river water > well water > snow. River water and groundwater are closely linked hydraulically, and the evaporation of river water and lake water is the strongest among the water bodies in the basin. (2) The maximum values of lake water δ2H and δ18O are observed in Hobson Lake at the bottom of the basin, and the minimum values are observed in the upper east branch of the river water collected from winter to the wrong lake. It shows that the δ2H and δ18O of lake water in the northern part of the Qinghai-Tibet Plateau are more positive than those in the south, and there is an obvious elevation effect. (3) Moreover, a significant linear relationship is found between river water δ2H and δ18O: δ2H = 4.93 δ18O - 29.6 (R2=0.97). The enrichment of hydrogen and oxygen isotope components is primarily controlled by the influence of river evaporation; strong evaporation effect in the upper reaches of the river; and high deuterium excess caused by high altitude, low temperature, and low air humidity. (4) Compared with water, the depletion of hydrogen and oxygen-stable isotopes in ice at the same location results from repeated evaporation and condensation of local water vapor.
 An assessment of groundwater, surface water, and hydrochemical characteristics in the upper valley of the Bortala River DING Qizhen,LEI Mi,ZHOU Jinlong,ZHANG Jie,XU Dongsheng 2022, 39 (3):  829-840.  doi: 10.13866/j.azr.2022.03.16 Abstract ( 95 )   HTML ( 4 )   PDF (8219KB) ( 52 )   This paper examined the hydrochemical characteristics and water quality status of groundwater and surface water in the upper valley of the Bortala River, Xinjiang. The examination was based on 36 groups of water sample data. Hydrochemical characteristics and their influencing factors were studied by Piper diagram, correlation analyses, Gibbs diagram and ion ratio, and the entropy-Bayesian water quality evaluation model, Wilcox and USSL diagrams were used to evaluate water quality. Results of hydrochemical analyses showed the following: (1) the mechanical well water, spring water, and river water in the study area were weakly alkaline fresh water, and total hardness (TH), F-, $N O 3 -$ and total dissolved solids were aligned as mechanical well water > spring water > river water, whereas $H C O 3 -$ and Ca2+ were the dominant anions and cations, respectively. Contents of each component in the upper Bortala River increased along the river. (2) The main hydrochemical types of mechanical well water and spring water in the area were the HCO3-Ca type, and main hydrochemical types of river water were the HCO3-Ca and HCO3·SO4-Ca·Na types. Hydrochemical characteristics were controlled mainly by rock weathering, and hydrochemical components were mainly from carbonate rock weathering. Evaporation rock dissolution also occurred and it was affected by cation exchange and human activities. The water quality evaluation of drinking water showed that 82.6% of mechanical well water and 100% of spring water were suitable for drinking, basically suitable for drinking, or suitable for drinking after proper treatment. Water sample points that were not suitable for drinking were affected mainly by excessive Fe, F-, and $N O 3 -$. River water, well water, and spring water were suitable for the evaluation of irrigation water quality.
 Temporal and spatial variation change of groundwater environment in the salinized irrigation districts under the background of water-saving reconstruction CUI Jiaqi,LI Xianyue,SHI Haibin,SUN Yanan,MA Hongyu,JIAN Wenhao 2022, 39 (3):  841-852.  doi: 10.13866/j.azr.2022.03.17 Abstract ( 59 )   HTML ( 5 )   PDF (9202KB) ( 27 )   Groundwater is an important resource in the arid region of Northwest China, and large-scale water-saving transformation projects are bound to cause changes in the groundwater environment. On the basis of the spatial-temporal probability distribution, the spatial-temporal variations of groundwater depth and salinity were explored in the Yongji irrigation area of the Hetao Irrigation District before the Agricultural Water-saving Transformation Project (AWSTP) (1998-2000), at the initial stage (2001-2006), the middle stage (2007-2012), and the late stage (2013-2018). The Kriging method was used to analyze the probability distribution of groundwater depth and salinity under different threshold conditions before and after the AWSTP. The results show that as the AWSTP advanced, both the buried depth of groundwater and groundwater salinity increased. In the late stage of the AWSTP (2013-2018), the average buried depth of groundwater increased by 0.36 m, and groundwater salinity increased by 1.37 g·L-1 compared with preproject measures (1998-2000). On a spatial scale, 33% of the high-probability area of shallow groundwater (i.e., groundwater depth less than 2.0 m; probability of occurrence above 0.5) transitioned to the high-probability area of deep groundwater (i.e., groundwater depth greater than or equal to 2.0 m). Shallow groundwater has been affected by urbanization (with a large amount of groundwater exploitation), and groundwater depth has increased significantly in the central, southern, and northern parts of the area. The high-probability areas of groundwater salinity less than 2.5 g·L-1 and greater than or equal to 3.0 g·L-1 have expanded by 17% and 4%, respectively. In other words, the south-central part of the study area tended to desalinate, whereas the northern and eastern edges tended to mineralize. The 21 year average deep groundwater (i.e., groundwater depth greater than or equal to 2.0 m) with high-probability areas accounted for 39% of the total area and is mainly concentrated in the south-central area. The high-probability areas with salinity less than 2.5 g·L-1 accounted for 67% on average, and the high-probability areas with salinity greater than or equal to 3.0 g·L-1 were concentrated in the northern region and accounted for 27% of the total area. The AWSTP has resulted in an increase in groundwater depth (i.e., effectively reduced the groundwater level). Although groundwater salinity is increasing, the mineralized areas are mostly concentrated near the drains. Further improvements to the drainage system are recommended.
 Comparison of phytoremediation effects of Medicago sativa and Coreopsis basalis on crude-oil-contaminated soil in eastern Gansu Province JING Mingbo,WANG Jincheng,ZHANG Wei,ZHOU Lihui,ZHANG Shaopeng 2022, 39 (3):  853-862.  doi: 10.13866/j.azr.2022.03.18 Abstract ( 64 )   HTML ( 7 )   PDF (5561KB) ( 23 )   Phytoremediation is the most eco-friendly, economically sustainable, cost-effective technology available for the biodegradation of soil pollutants, while crude-oil-contaminated soil is susceptible to many factors in the process of phytoremediation, including climatic conditions, landform and soil properties, etc. The main properties of the Loess Plateau are high degree of salinization, an arid, and lack of soil fertility, thereby there are obvious regional vegetation distribution in this area. Compositae have strong drought resistance and tolerance and it is a ubiquitous plant growing wild and widely distributed throughout Northwest China. However, the phytoremediation effect of crude oil contaminated soil by Compositae has not been further studied in the Loess Plateau. Thus, in order to analyze and compare the phytoremediation efficiency of Medicago sativa and Coreopsis lanceolata on oil-contaminated soil in eastern Gansu Province of the Loess Plateau. The indigenous plants M. sativa and C. lanceolata were selected as the test plants, and a five months site remediation experiment was conducted in Changqing Oilfield Company, Qingyang City of Gansu Province. The changes of TPH (Total petroleum hydrocarbon, TPH) removal rate, plant growth index, soil physical-chemical properties and enzyme activities as well as microbial community structure in root-zone soil of M. sativa and C. lanceolata under different crude oil concentrations, i.e., light pollution group (TPH=3%), moderate pollution group (TPH=7%) and heavy pollution group (TPH=9%), were measured. We found that: (1) With the crude oil concentration increase from 3% to 9%, the removal rates of TPH in the root-zone soil of M. sativa were 69.88±4.16%、42.59±3.94%、19.20±2.77% and 2.01±0.19%, while were75.33±2.91%、74.87±2.79%、42.47±1.99% and 2.20±0.51% in the root-zone soil of C. lanceolata, respectively. (2) The emergence rate and chlorophyll a/b value of the two tested plants were not significantly affected by crude oil concentrations at 3%, while the effects of oil concentrations ranged from 7% to 9% on seedling emergence rate, chlorophyll a/b value, aboveground and underground dry weight, root vitality and root-shoot ratio of M. sativa were relatively significant (P<0.05). (3) Oil concentration ranged from 3% to 7% had relatively little inhibition on soil available P content in the root-zone soil of M. sativa (P<0.05), while the soil pH, urease and alkaline phosphatase activities in the root zone of C. lanceolata were significantly higher than those of M. sativa in the concentration ranged from 7% to 9% (P<0.05). (4) High throughput sequencing results showed that the relative abundance of crude oil degrading bacteria, i.e., Alcanivorax, Marinobacter, Halanaerobium, Halomonas and Nocardioides, etc. in the root-zone soil of C. lanceolata were significantly higher than those in the M. sativa (P<0.05). (5) Variance decomposition results indicated that the inhibition of oil concentration on the physiological characteristics of M. sativa was the decisive factor limiting the root zone soil TPH removal rate, while the combined effect of soil physicochemical × microbial characteristics was the main environmental factor determining the root zone soil TPH removal rate of C. lanceolata higher than that in the treatment group of M. sativa (P<0.05). In conclusion, the phytoremediation efficiency of C. lanceolata on crude-oil-contaminated soil in eastern Gansu Province of the Loess Plateau is better than that of M. sativa.
 Distribution pattern and driving mechanisms of the sand plant Leymus racemosus in the Junggar Basin ZHANG Lin,ZHANG Yunling,MA Songmei,ZHANG Dan,HE Lingyun 2022, 39 (3):  863-871.  doi: 10.13866/j.azr.2022.03.19 Abstract ( 63 )   HTML ( 7 )   PDF (4563KB) ( 39 )   Our objective was to simulate and predict ecological suitability, possible suitable distribution range, spatial distribution characteristics, and possible response to future climate change of Leymus racemosus (Lam.) Tzvelev in Xinjiang. The data in this study were based on 24 natural distribution sites and eight environmental factors of Leymus racemosus and were analyzed using GIS spatial analysis and the MaxEnt model. The suitable distribution range and changes in the distribution pattern of Leymus racemosus in Xinjiang under the present climate (1970-2000), the 2050 period (2041-2060), and the 2070 period (2081-2100) for the “Middle of the Road” narrative (SSP2) of the shared socioeconomic pathways were analyzed. We used multivariate environmental similarity surface analysis and the most dissimilar variable to explore the key climatic factors. Under the present climate, the suitable distribution area of Leymus racemosus accounts for 5.57% of the total area of Xinjiang, mainly concentrated in the low-cover grasslands near the Irtysh River. Compared with the present climate, the suitable habitat of Leymus racemosus will be significantly reduced by 0.99% and 1.33% in 2050 and 2070, respectively; its suitable habitat will be highly fragmented, and the center of its suitable habitat will move to the Northwest at higher latitudes and higher elevations. Factors that mainly influence the suitable distribution of Leymus racemosus in Xinjiang are the precipitation of the driest month, precipitation seasonality (Cv), and the standard deviation of seasonal temperature variation.
 A health evaluation of a Haloxylon ammodendron plantation in the Shiyang River lower reaches LI Xuening,XU Xianying,ZHENG Guiheng,MA Quanlin,ZHANG Yunian,LIU Hujun,ZHAO Peng,YANG Xuemei 2022, 39 (3):  872-882.  doi: 10.13866/j.azr.2022.03.20 Abstract ( 51 )   HTML ( 2 )   PDF (4016KB) ( 49 )   A Haloxylon ammodendron forest is a protected ecological forest in a desert area. It not only reduces the impact of wind sand disasters, controls soil erosion, and maintains the ecological stability of desert oasis but also improves soil quality and increases carbon storage of the desert ecosystem. Recently, the H. ammodendron forest has been declining in Minqin. Determining sustainable management of the artificial H. ammodendron forest is critical for the health status and function of wind prevention and sand fixation for this forest over time. In this study, the artificial H. ammodendron forest in the lower reaches of the Shiyang River was selected as the research focus. Through a literature review and expert consultation, a health evaluation system of the artificial H. ammodendron forest with 5 primary indicators and 19 secondary indicators was constructed. Analytic hierarchy process combined with an entropy method was used to determine the weight of each index. Based on the ecological health index (HI) and field survey data, the health status of the artificial H. ammodendron forest was evaluated. Results show the following: the HI value of the artificial H. ammodendron forest in the lower reaches of the Shiyang River is between 0.50 and 0.67; the average comprehensive HI is 0.617, which is in a sub-health state; and to improve the stability of the artificial H. ammodendron forest, we should take measures such as stubble and enclosure.
 Effects of deficit irrigation and film mulching on biomass and production of Cyperus esculentus in the southern Xinjiang Basin DING Ya,YANG Jianming,LI Li,ZHANG Zhihao,ZENG Fanjiang 2022, 39 (3):  883-892.  doi: 10.13866/j.azr.2022.03.21 Abstract ( 67 )   HTML ( 4 )   PDF (1138KB) ( 22 )   The effect of drip irrigation and film mulching of Yousha beans in the southern Xinjiang basin and the optimal irrigation system were explored to provide a reference for constructing a water-saving and high-yield management and cultivation mode. A 1-year experiment was conducted under conditions of film mulching (M) and no film mulching (NM). Addtionally, three water control levels were set, the irrigation frequency was 6-10 days, irrigation amounts of T1 and T2 were 3431.40 m3·hm-2 and 4133.85 m3·hm-2, respectively, and a local common irrigation amount was used as the control (CK, 5316.45 m3·hm-2) yield and water use efficiency. Results showed that the density of Cyperus esculentus. was significantly affected by water treatment (P<0.05), but the root: shoot ratio was not significantly affected by water treatment (P>0.05). Contents of crude fat, soluble starch, and soluble sugar of grass covered with a plastic film increased by 58.82%, 3.35%, and 17.20%, respectively, on average compared with those without plastic film. Contents of crude fat, soluble starch, and soluble sugar of tubers covered with plastic film were higher than those without plastic film and increased by 7.48%, 2.56% and 2.55%, respectively. Furthermore, there was no significant difference between water treatments (P>0.05) but they reached the maximum in the T2 treatment. The yield and water use efficiency increased first and then decreased with an increased irrigation amount. Under film mulching conditions, the yield of grass and tubers under the T2 treatment were the largest and were 3974.55 kg·hm-2 and 5253.85 kg·hm-2 and significantly increased by 6.45% and 36.95%, respectively, compared with the CK treatment (P<0.05). Compared with a condition of no film mulching, the average yield of T2 and CK significantly increased by 29.41% and 34.76%, respectively (P<0.05). The water use efficiency of grass and tubers in the T2 treatment was significantly higher than the CK by 38.63% and 34.33% (P<0.05), respectively. Compared with T2 (film mulching), the water use efficiency of grass and tubers treated with the CK and T2 under no film mulching conditions was significantly increased by 38.91% and 34.33%, respectively (P<0.05). There was no significant difference in the water use efficiency of grass (P>0.05), but there was a significant difference in the water use efficiency of tubers (P<0.05). Therefore, under film mulching conditions, the irrigation quota was 4133.85 m3·hm-2, which improved not only the quality and yield of Cyperus esculentus but also the water use efficiency and saved water resources, that is, under conditions of film mulching, the irrigation mode with an irrigation quota of 4133.85 m3·hm-2 showed economic and water-saving benefits.
 Response of drought on water and nitrogen utilization and carbohydrate distribution of Populus × euramericana ‘Biyu’ cuttings SHANG Jiazhou,ZHAO Yuqi,WANG Weifeng,GAO Tianhui,ZONG Yuzheng 2022, 39 (3):  893-899.  doi: 10.13866/j.azr.2022.03.22 Abstract ( 61 )   HTML ( 9 )   PDF (2929KB) ( 27 )   The ecophysiological response of poplar to soil drought and drought resistance strategies among species remained unclear. In this study, Populus×euramericana ‘Biyu’ cuttings grown in pots were used as materials. Changes of leaf gas exchanges, water and nitrogen use traits, growth, and carbohydrate allocation among organs under 2-year drought were investigated. Results showed that the leaves of 1-year-old poplar cuttings became smaller but thicker under drought with stable stomatal conductance, and transpiration rate. The net photosynthesis rate decreased by non-stomatal inhibition, and the transient water and nitrogen use efficiency significantly decreased. In the second year, the leaves became even smaller and thicker with a higher carbon and nitrogen ratio. However, leaf nitrogen contents remained unchanged, which could improve leaf drought resistance. The net photosynthesis rate increased slightly, and transient water and nitrogen use efficiency remained stable. Moreover, moderate drought significantly increased whole-plant nitrogen use efficiency. Under a 2-year drought treatment, the growth significantly decreased. More biomass and non-structural carbohydrates allocated into the stem but not in the root system, and the root and shoot ratio became smaller, which are detrimental to the water and nitrogen uptake in the root and whole-plant drought resistance. Therefore, P.× euramericana ‘Biyu’cuttings can reduce water consumption in smaller but thicker leaves under drought, with high leaf nitrogen content, but this response could reduce the leaf area used for photosynthesis, resulting in decreased growth and smaller roots. These results indicated that P.×euramericana ‘Biyu’ has low drought resistance, which is not suitable for large-scale afforestation in arid and semi-arid areas.