Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Habitat quality is an important basis for biodiversity conservation and improvement of the regional ecological environment. With an ecological civilization construction as the background, the spatial- temporal adaptation and driving mechanism of habitat quality is significant to study. Based on land use data in Shaanxi Province in 2000, 2010, and 2020, the characteristics and driving factors in the spatial-temporal adaptations of the quality of habitat in three regions were analyzed using the InVEST model, Theil index model, and geographic detector model. The results showed the following: (1) from 2000 to 2020, the average quality of habitat showed a stable and slightly increasing trend, and the spatial distribution difference was obvious, with the average habitat quality in southern Shaanxi and northern Shaanxi being higher compared to Guanzhong; (2) the difference of habitat quality among the three regions was larger in southern and central Shaanxi compared to northern Shaanxi; (3) the province and the driving factors in the three different regions, vegetation and terrain factors for the habitat quality, and land utilization factor are the main influencing factors of the three major areas affected by the spatial scale. As time goes on, the influence degree gradually strengthens, and the terrain and vegetation factors have different effects on three areas; (4) In addition to single factors, significant impacts on habitat quality changes in the three regions produced cooperative effects on socioeconomic and natural environmental factors.
Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
The Tazhong-38th Corp Desert Highway, currently under construction, extends from the hinterland of Taklamakan Desert to its southeastern edge. Different degrees of wind and sand hazards are distributed along the whole route, posing serious threats to the construction, service, and maintenance of the desert highway. Based on remote sensing image interpretation and wind data analysis, the wind and sand environment characteristics and dune movement rules in different sections of the desert highway were assessed, and a corresponding sand hazard prevention system framework is proposed. Our analysis showed that the prevailing wind directions along the desert highway are NE, ENE, and E, and the frequency of sandy wind increases from 21.7% to 33.8%. The wind direction characteristic develops from sharp bimodal to blunt bimodal, and the wind and sand hazards gradually become more severe: the drift potential along the section ranges from 178.23 to 309.43 VU, the wind energy environment is low to medium, the resultant drift direction is between SW-WSW, and the wind direction variation rate is medium. The annual average dune movement speed is between 3.16 and 6.26 m.a-1 , and there are obvious spatial differences in dune movement speed and direction. The consistency between dune movement direction and the resultant drift direction is poor in some sections. Based on the above environmental characteristics of the desert highway sections, a sand control system for the desert highway, combining blocking and solidification, is proposed. The results of our study have practical application value in the development of prevention and mitigation measures for desert highway sand damage.
Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
With the basis of climate change, nitrogen deposition will have an impact on N2O emissions between the soil and atmosphere in the alpine wetland in the arid region of Northwest China. Taking the alpine wetland at Swan Lake of Bayinbuluke in the middle of Tianshan Mountain as a study area, three nitrogen addition treatments (0, 10, and 20 kg·hm− 2 ·a − 1 ) were set in different water conditions (perennial seeper area, seasonal water area, and perennial dry area). The measurement of N2O was made via static chamber-gas chromatography during the growing season. The relationship between N2O emissions and main environmental factors was explored. The results showed that the following: (1) increased N significantly contributed to N2O emissions under different water conditions in the alpine wetland ecosystem (P < 0.05). Under 0 kg·hm− 2 ·a − 1 treatment, the N2O accumulation showed an uptake from the ecosystem with the growing season. Under 10 and 20 kg·hm− 2 ·a − 1 treatments, the N2O accumulation were emitted. The cumulative N2O emissions increased significantly when nitrogen deposition increased in different water conditions. Increased nitrogen deposition influenced the wetland ecosystem from N2O to sink to the N2O source. (2) nitrogen application significantly affected the rate of N2O emissions from the ecosystem (P < 0.01). In seasonal water area, the relationship between the average N2O emission rate (F), nitrogen addition (N), and soil temperature (T) at a depth of 5 cm was in accordance with the multiple first- order equation (F = −2.763 + 0.209N + 0.151T, R2 = 0.483, P < 0.01). Therefore, N deposition increases N2O emissions in the alpine wetland in the arid region of Northwest China.
Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Land expansion is facing problems, such as extensive utilization of resources, destruction of ecological environments, and imbalanced regional development. Clarifying the adaptation of the land’s functions is conducive to regional coordinated development. The main contents include evaluating the adaptation of the land’s functions in the Hohhot- Baotou- Erdos region in 1990, 2000, 2010, and 2018, and analyzing its temporal and spatial adaptation characteristics. This paper evaluates the synergy/trade-off relationship of the adaptation of the land’s functions based on the coupled coordination model and the bivariate spatial autocorrelation model. The main conclusions are as follows: first, the land functions in the region of Hohhot-Baotou-Erdos have significant temporal and spatial differentiation characteristics, the production/living functions rise locally, and the spatial distribution takes each municipal district as the high- value center circle/semi- circle distribution pattern with a decreasing outward gradient; second, the overall trend of the ecological function is continuously downward and its spatial agglomeration has the scale-dependent effect of a natural landscape; third, the synergy trade- off relationship of the spatial-temporal differentiation characteristics of the land’s functions are obvious. The coupling coordination degree of land and spatial functions of each flag county has been on the rise from the time sequence adaptation characteristics, and the number of flag counties increases; however, the overall level is low; fourth, the synergy/trade-off relationship of various functions in land space has obvious spatial differentiation characteristics, and this relationship alternately changes with time. The spatial distribution and agglomeration effect of the synergy/trade-off relationship of production and living functions is significant, and the spatial distribution of the this relationship between production/living ecological functions tends to be discrete. Ultimately, the spatial coupling effect of the synergy/trade-off relationship between various functions is at a low level as a whole.
Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
In China, the county is not only an important contributor to carbon emissions and a major carbon sink zone but also a key administrative unit for the implementation of China’s national goals for carbon peak and carbon neutrality. Focusing on Qingcheng County as a typical county in the Loess Plateau, we investigate the carbon emission characteristics and spatiotemporal patterns, to raise awareness of the need for ecological protection of the Yellow River Basin, while achieving high- quality development and green and low carbon transformation. The key results of our study are as follows. (1) The change and structure of county carbon emission in underdeveloped areas have distinct characteristics. Industries below the designated size are the largest source of carbon emissions in Qingcheng County, having a low proportion of industrial carbon emissions but a relatively high proportion of service sector and household carbon emissions. (2) The spatial distribution of carbon emissions in Qingcheng County conforms to the Pareto Principle: 80% of carbon emissions are concentrated in 20% of the region, which is characterized by“overall dispersion and local agglomeration”. The high carbon zones are mainly concentrated in the valley, broken plateau area, and urban area. The medium carbon zones are mainly distributed in the broken plateau area and along the traffic line. Low carbon zones are widely distributed in ridge, hill, and gully areas. (3) The county carbon emissions in the Loess Plateau show clear temporal and spatial pattern differences that are affected by differences in topography. The largest patch index of medium and high carbon zones, such as urban areas, industrial zones, and major towns, increases, the integrity improves, the diversity of carbon sources decreases, and the types tend to be single. The carbon source diversity increases and the aggregation degree decreases in the ecotone between medium carbon zones and low carbon zones, such as transportation lines and residential areas.
Subjects: Geosciences >> Hydrology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
To investigate the influence of mine water discharge on soil microbial community structure and diversity in the desert grasslands of Ningxia, high-throughput sequencing was used to analyze the composition of bacteria and fungi communities in the 0-10, 10-20, and 20-30 cm soil layers along the shore, near-shore land, and natural areas of the mine water discharge lake. The main factors of the mine water influencing the soil microbial community structure and diversity were revealed by combining these factors with soil physical, soil chemical, and other habitat factors. The results show that the mine drainage in the study area significantly changed the community composition of soil bacteria and fungi as well as the relative abundance of the soil bacteria and fungi. The main dominant phyla of bacteria in the shoreland, coastal land, and natural areas were Actinobacteria and Proteobacteria, and the main dominant genus of bacteria was norrank_f_norrank _ o _ norrank _ c _ MB-A2-108. Ascomycetes was the main dominant phylum of fungi in the shoreland, coastal land, and natural areas, whereas unclassified_c_Sordariomycetes and Preussia were dominant in the shoreland area and the coastal land and natural areas, respectively. The drainage of mine water leads to significantly higher soil salinity and moisture in the waterfront area of desert grassland than in the coastal land and natural areas. Salt was found to inhibit the growth of soil bacteria and fungi but, at the same time, promoted the enrichment of halophilic bacteria in the study area. The diversity and richness of soil bacteria and fungi in shoreland areas are significantly lower than the corresponding values in natural areas, which further shows that mine water has a significant impact on the richness and diversity of soil bacteria and fungi. There was little difference in the richness and diversity of bacteria and fungi in the different soil layers. The analysis of soil environmental factors along with the diversity of soil bacteria and fungi showed that soil salinity, water content, organic carbon, and pH are the main influencing factors on the diversity of soil bacteria and fungi in the desert grasslands of Ningxia.
Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Microorganism and enzyme activities in the soil are important biological indicators of soil quality. Farmland soil polluted by heavy metal in Ningyuanbu Town of the Jinchuan District in Gansu Province was the object of this study. To analyze the content of heavy metals (Zn, Pb, Cd, Cr, Cu, Ni, As, Hg), microorganisms (bacteria, fungi, actinomycetes), and enzyme activity (urease, alkaline phosphatase, catalase, dehydrogenase), 26 samples in soil layers of 0-20 cm and 20-40 cm were collected. The results showed that the over-standard rates of Ni, Cu, and As in the soil layer of 0-20 cm were 15.4%, 30.8%, and 38.5%, respectively. The over-standard rates of Ni, Cu, and As in the soil layer of 20-40 cm were 7.7%. There was a negative correlation between Pb, Hg, Ni, Cu, Cd, and As, along with bacteria, urease, alkaline phosphatase, catalase, and dehydrogenase. Cr showed a positive correlation with fungi and actinomycetes. Zn showed a positive correlation with bacteria. Pb, Zn, and Cr were the major factors that dominated soil biological traits, and the contribution rate was 72.4% , 16.2% , and 4.9%, respectively. Catalase activity was sensitive to nickel, copper, cadmium, and arsenic pollution, which can be used as an effective index for the evaluation of soil quality in these areas.
Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Blowout is an important manifestation of grassland desertification that is a common for a wind erosion landform in sandy grassland and is highly destructive to grassland vegetation. The blowouts that were in the active development stage of HulunBuir grassland were the object of this research, and the surrounding grassland was the control in which the soil moisture was measured in different locations and different depth. The results show the following: (1) Blowouts caused the“crevasse”effect of soil moisture in grassland that lead to a significant decrease in the soil of the surrounding grassland in a range of nearly 20 m. A close proximity to the pit results in lower soil moisture, A“dry zone”was formed in the range of 0-3 m at the edge of the pit, and the soil moisture was reduced by 45.15% compared with the control. (2) Soil moisture of the pit decreased by 44.44%, and no significant difference was observed in the soil moisture between the surrounding sand accumulation area and the lightly overlying sand area compared to the control. (3) There was a great difference in soil moisture of the pit in the soil layers and sand accumulation area. Cv could reach more than 50%. As soil depth increased, the soil moisture increased first and then decreased. (4) The sand accumulation area of blowouts could realize a certain“water storage”effect after the rainy season, the pit and edge zone had a serious“water loss”effect. The soil was extremely dry soil provided conditions for the expansion and morphological development of blowouts.
Subjects: Geosciences >> Hydrology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
A quantitative analysis of runoff variation characteristics is the basis for finding out its impact mechanism, and it is also an important basis for accurately evaluating water resources. This study used eight annual distribution indexes, such as the Gini coefficient and Lorentz asymmetry coefficient, combined with the M-K test、R/S analysis, and other mathematical statistics methods, to comprehensively analyze the process of the runoff of the upper reaches of the Shule River from the annual and interannual levels. The results showed that the following: (1) during the year, a unimodal distribution was shown, which was mainly concentrated in the flood season concentration degree (D), inhomogeneous coefficient (Cv), Gini coefficient (GI), relative change range (Cm) decreased respectively at the rate of - 1.053 · (10a)- 1 , - 0.015 · (10a)- 1 , - 0.009 · (10a)- 1 ,- 0.643 · (10a)- 1 , complete adjustment coefficient (Cr), Lorentz asymmetry coefficient (S), concentration period (Cn) all decreased at the rate of -0.006·(10a)-1 . The distribution tended to be uniform gradually according to the changing trend of its characteristic index during the year. (2) The annual runoff showed an overall increasing trend, but an abrupt change occurred in 1997, and the average annual runoff afterward increased by 59% compared before the change. (3) The runoff generally showed an upward trend in all four seasons, among which the trend rate was the greatest in the summer and the smallest in the winter. After the abrupt change in the 1990s, the average runoff increased significantly compared to before the abrupt change, and the change range was in the following order: autumn (76%) > winter (74%) > summer (58%) > spring (45%). (4) The annual and seasonal runoff in the upper reaches of the Shule River had multiple time characteristic scale periods, and the first major cycle were both 56 years. (5) According to the predicted runoff from 2022 to 2024, it was found that the runoff of the upper reaches of the Shule River will continue to increase in the next three years. These results provided a scientific basis for accurately grasping the runoff variation laws and characteristics of the upper reaches of the Shule River and had certain guiding significance for the sustainable development and utilization of water resources in the Shule River Basin and the study of the runoff variation laws in inland river basins.
Subjects: Geosciences >> Hydrology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Based on the satellite data, the water level and area information of Lake Issyk-Kul was extracted, and the water volume was reconstruct; combined with CRU meteorological data from 1960-2020, the temperature and precipitation observation data from 1960- 2000 at the Cholpon- Ata meteorological station and the water volume observation data into the lake, the lake water balance model was established to analyze the changing characteristics of each element of the water balance and to explore its influencing factors. The results indicated that: (1) Since 1960, the water volume of Issyk-Kul Lake has undergone a process of continuous decrease and fluctuating increase, with 1998 being the inflection point of the change; from the 1960s to the mid-1980s, the water volume into the lake decreased continuously mainly due to the influence of irrigation diversions, and then turned to an increasing trend after 1986 with the decrease of irrigation water and the increase of precipitation and glacial meltwater; precipitation in the lake area increased at a rate of 9.1 mm·(10a)-1 , and the evapotranspiration tends to increase significantly with increasing temperature and lake area. (2) Before the mid-1980s, Issyk-Kul had a negative water balance in most years, and groundwater continued to recharge the lake; since 1986, the water balance deficit of the lake gradually decreased, and since 1998, the positive balance has been dominated. (3) The interaction of water balance components such as runoff, precipitation and evaporation determines the changes in lake water volume, while climate change in the flow-producing areas and irrigation diversions in irrigation areas indirectly drive the changes in lake water volume by changing runoff; from 1960 to 1986, human activities, mainly irrigation diversions, were the dominant factor driving the changes in Issyk- Kul water volume, with a contribution of 71.6%, and since 1987 the cumulative contribution of climate change factors to changes in lake water volume exceeds 80%.
Subjects: Geosciences >> Hydrology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
From 2000 to 2020, remote sensing data, such as MODIS and FLDAS, the Mann- Kendall method, Theil-Sen median trend analysis, Pearson correlation analysis, and the water balance principle, were applied to explore the spatial distribution and temporal variation patterns of actual evapotranspiration in the Ili RiverBalkhash Lake basin, along with its main influencing factors. In addition, changes in the ecosystem water supply were discussed. The results were as follows: (1) the upper, middle, and lower Ili River-Balkhash Lake basins had an average annual evapotranspiration of 439.0 mm, 317.9 mm, and 201.1 mm, respectively. The daily evapotranspiration in the upper and middle basins was the greatest in the summer, while the lower basin had the greatest daily evapotranspiration in the spring. The intra- annual distribution of evapotranspiration in the upper and middle basins was“unimodal,”with peaks in July and June, respectively. It was“bimodal”in the lower basin, with peaks in March and November, respectively. (2) The annual evapotranspiration increased in both the upper and lower basins, with the highest concentrations in the upper Ili River valley, Tianshan Mountains, and near the Ili River delta in the lower basin. Compared to the 2000s, the average annual evapotranspiration in the Ili River valley and Ili River delta increased by more than 10% in the 2010s. (3) Based on the Pearson correlation analysis, the upper and middle basins showed high positive correlations with temperature and NDVI, whereas the lower basin showed high positive correlations with soil moisture. (4) From 2000 to 2020, the basin's total water supply service decreased, with several shortfalls in the upper basin and shortfalls in the middle and lower basins beginning to appear in 2020. The balance of water supply and demand must be ensured by controlling the total amount of water being used and by improving water use efficiency.
Subjects: Geosciences >> Hydrology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
The water ecological security evaluation index system was constructed based on the complex ecosystem (social-economic-compound ecological system and pressure-state-response model) concept. From 2009 to 2018, the statistical data of Shiyang River Basin were used. The fuzzy system analysis method and BP neural network model were used to analyze the many aspects of the driving mechanism of water ecological security in the Shiyang River Basin. The results showed that the precipitation change, livestock, ratio of ecological environment water consumption per unit area to total water use, rainwater utilization, and diameter fouling were the main influencing factors of water ecological security in the river basin during the study period. From the WSENCE system view, the current influence degree of water ecological security were ranked as follows: resources subsystem≥social subsystem>economic subsystem>environment subsystem>ecological subsystem; from the PSR system view: response subsystem>pressure subsystem>status subsystem; the resources and pressure subsystems were the main driving force of water ecological security from 2009 to 2018. The pressure and environment subsystems were the main driving force of water ecological security from 2019 to 2023. In the last ten years, water ecological security of the Shiyang River Basin was still in the levelⅠarea (poor) and levelⅡ area (in general). Overall, the situation was poor
Subjects: Geosciences >> Hydrology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
The Qaidam Basin is a typical arid inland area in China. Recognizing the interaction between surface water (SW) and groundwater (GW), characteristics of water chemistry, and change law along the river in the basin is significant for developing and utilizing regional water resources and ecological protection laws. Hydrochemical and statistical analysis methods were used to study the SW- GW interactions, with the hydrochemical characteristics and differences being analyzed based on field investigation and analysis. According to the controlling effect of geological structure, strata, and landform on the hydraulic connection, the SW-GW interactions are divided into the following types: bedrock barrier + lithology control, lithology control + hydrometeorological influence, and lithology control. The hydrochemical types change from Ca to Na or Mg and from bicarbonate to chloride ion from the mountainous area to the tail area. The changing trends of the hydrochemical influence mechanism along the flow paths gradually change from water-rock interaction to evaporation-precipitation. The transformation of the SW-GW interaction in the inter-mountain valley and front of the alluvial-proluvial fan causes a local reversal of the changing law of hydrochemical characteristics along the river that are influenced by a bedrock barrier and lithology control. This is due to the lithology differences of aquifer, Na+ , Cl− , and SO2 - 4 that are dominant in SW and GW in the south. Ca2+ and HCO− 3 are dominant in the north and east, and the F− concentration in the north is higher compared to other watersheds
Subjects: Geosciences >> Atmospheric Sciences submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Based on the annual ring cores of Larix principis- rupprechtii collected from three altitudes of Luya Mountain, the residual chronology of earlywood and latewood tree rings was established. Using the method of tree ring climatology and taking 1984/1985 as the boundary, heterogeneity characteristics of radial growth of earlywood and latewood of L. principis-rupprechtii at different altitudes in response to climate factors in 1957- 1984 and 1985-2020 were discussed. The results showed that the following: (1) the radial growth changes of earlywood and latewood were difficult to fit the climate warming trend in the study area from 1957 to 2020, and the response to temperature is separated. (2) From 1957 to 1984, no significant correlation existed between low altitude and climate factors in the growth of earlywood. Precipitation during the growing season, which had a significant positive correlation with precipitation in March and negative correlation in June, had an obvious restrictive effect on the growth of earlywood at medium and high altitudes. The precipitation factors in the growing season from 1985 to 2020 had a significant positive correlation with precipitation in April and had an influence on the growth of earlywood at a low altitude, thereby enhancing it. The growth of earlywood at medium and high altitudes was mainly affected by precipitation in January, and the restrictive effect on the growth and development of earlywood at medium and high altitudes was weakened. (3) Nutrient accumulation before growth is very important for latewood growth of L. principis- rupprechtii: from 1957 to 1984. The chronology of latewood width at three altitudes showed a significant positive correlation with precipitation in May. From 1985 to 2020, the radial growth of tree latewood was limited by the comprehensive factors of temperature and precipitation before growth in November of the previous year and January, March, and May of the current year. (4) In two different time periods, the change of the pattern of earlywood growth at a low altitude may have been caused by drought stress, which was caused by increased temperatures. The difference in the growth patterns of earlywood at medium and high altitudes was most likely due to the fact that the increased temperature alleviated the inhibitory effect of low temperature on the growth of earlywood at medium and high altitudes. With global warming, there are different response characteristics and response modes of earlywood and latewood of L. principis-rupprechtii of three altitudes of Luya Mountain to climate factors in two time periods. There is a certain “response divergence”phenomenon with the response of climate factors that should be considered concerning future climate reconstruction in this area
Subjects: Geosciences >> Atmospheric Sciences submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Different methods have different research results on the duration and variation of this phenomenon, causing dissidence. In this paper, the evaluation index of climate warming and humidification was constructed by combining meteorological factors and drought and vegetation indexes. The surface moisture index (Hi), selfchecking Palmer drought index (sc_PDSI), and annual NDVI were used to construct the evaluation index of the warming and humidification grade based on the method of data normalization. This kind of index was used to comprehensively evaluate the spatial and temporal distribution of climate warming and humidity in Qinghai Province over the past 60 years to verify the applicability of the index in different time series lengths and cover different factors. The evaluation results show the following: (1) the overall climate of Qinghai Province over the past 60 years is in the stage of obvious indigenous warming and micro- humidifying. The affected regions are concentrated in parts of the Qilian Mountains in the southeast, southern to the southeast of the Yellow River Basin and Lancang River Basin. (2) Climate change has not changed the distribution pattern of climate warming and water resources in Qinghai Province over the past 60 years. (3) This kind of index has positive applicability for regional long-time scale warming and humidifying evaluation and can objectively and timely reflect the warming and humidifying situation of the evaluation area
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
With the foundation of global climate change in recent years, droughts in various climatic areas in Inner Mongolia may bring unpredictable disaster risks to local agricultural production. The whole region was divided into five climatic areas, and monthly data was received from 46 meteorological stations from 1981 to 2012. Twenty meteorological stations from 2014 to 2020 were selected to calculate the different time scales of the standardized precipitation evapotranspiration index (SPEI) using precipitation and reference evapotranspiration from the Penman-Monteith method to reveal the drought characteristics and its dominant meteorological factors during the crop growing season (May-September) in Inner Mongolia. A monthly drought during the crop growing season was revealed. The high-incidence month and region of drought in the growing season in various climatic areas were identified by the SPEI of a 1-month scale, and a stepwise linear regression method was selected and verified to extract the dominant meteorological factors driving the drought in each month and the whole growing season in various climatic areas. Results indicated that the following: (1) from the interannual changes, the drought from 1998 to 2008 was more serious, and the drought in other years was less serious. (2) The largest drought area and degree appeared in May during the crop growing season. The probability of moderate drought in the moist and semi- humid area was 37% higher compared to the hyper- arid area, while the extreme drought probably occurred in the moist and semi-humid area and dry and semi-humid area. (3) Dominant meteorological factors driving the drought varied in the crop growth period of various climatic areas in Inner Mongolia. Precipitation and a minimum temperature were the main impact factors for a drought in the crop growing season. (4) Using limited meteorological data, the regression models in each climate region performance well can be used to estimate the monthly SPEI. The results provide a theoretical basis for scientific evaluation of drought characteristics in the spring maize growing season and formulates reasonable measures of response to the drought.
Subjects: Geosciences >> Hydrology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
Meteorological stations in Xinjiang are sparse and unevenly distributed, resulting in drought monitoring based on in-situ observations in Xinjiang which are insufficient in spatial representativeness. Remotesensed precipitation products have the advantages of wide coverage, high spatial resolution, and timeliness compared to data from stations. Thus, remote-sensed precipitation products are important for drought monitoring in Xinjiang with scarce in-situ observations. Multi-Source Weighted-Ensemble Precipitation (MSWEP) has been applied in various applications worldwide. With the foundation of global climate change, Xinjiang has experienced an increasing trend in the frequency of droughts and the variability of precipitation. This paper evaluates the accuracy of the MSWEP products using data from 106 observatories. Based on the Standardized Precipitation Index (SPI), MSWEP was adopted to study the temporal variations in dry/wet conditions, identify drought events, and study drought characteristics in Xinjiang from 1980 to 2021. The main results were as follows: (1) MSWEP was highly correlated with data from in-situ stations (>0.8), which supports its application in drought monitoring. (2) Xinjiang had become more humid in the studied period. (3) Thirteen severe drought events were identified since 1980. Among them, the one from 1985 to 1987 was the most severe, and the one from May-October, 2009, was the most intense. (4) Drought events have various features in duration, intensity, and severity. Some droughts were intense with a short duration, while others were long and more severe. Overall, MSWEP has a high potential for drought monitoring, especially for regions where ground-based observatories are scarce. Based on MSWEP, Xinjiang was found to experience a wetting trend and frequent drought events with different characteristics.
Subjects: Geosciences >> Cartography submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
The study of snowline altitude changes at the end of the melting season is helpful to predict future trends of snow systems in order to understand the regional and global climate changes. The remote sensing extraction method of region snowline altitude was developed based on the Google Earth Engine and Landsat satellite data. From 1991 to 2021, the snowline altitude at the end of the melting season in the four basins of the Tianshan Mountains was extracted. The variation characteristics of snowline altitude and its relationship with meteorological factors were carefully and accurately estimated. The results were as follows: (1) the extended snowline altitude at the end of the melting season correlated well with the snow cover extent (minimum) at end of the melting season, which was extracted by Sentinel-2. The overall accuracy was 91.6%, and the Kappa coefficient was higher than 0.9. The regional snowline altitude at the end of the melting season was accurately obtained with this model. (2) Generally, the snowline altitude at the end of the melting season in the study area showed an obvious increasing trend over the last 30 years. The increase rate was between 2.7 m·a-1 and 6.4 m·a-1 . The rise rate of the snowline altitude in the Manas River Basin was the fastest (6.4 m·a-1 ), while the rise rate of the snowline altitude in the Akeyazi River Basin was the slowest (2.7 m·a-1 ). (3) The summer temperature was the main factor that affected the change in the snowline altitude at the end of the melting season in the study area (P < 0.05), while the effect of precipitation was relatively weak.
Subjects: Geosciences >> Geography submitted time 2022-12-14 Cooperative journals: 《干旱区研究》
Abstract：
The arid regions of Central Asia, which are“upstream”of China in terms of their influence on weather and climate, are characterized by a general shortage of water resources and the fragility of ecosystems. The atmospheric water cycle is the key link in the transformation of water resources and ecosystems in this region. In this study, we reassessed the temporal and spatial variation of water cycle elements, such as atmospheric water vapor content, water vapor budget, precipitation, and actual evaporation, in the arid region and subregions of Central Asia, from 1979 to 2018. The results of our analysis show clear spatial differences in the water cycle elements of Central Asia. Precipitation and actual evaporation are high in mountainous areas, such as Tianshan Mountains and Pamir and surrounding oasis areas, and low in the desert plain areas, whereas atmospheric water vapor content shows an opposite pattern. In terms of temporal changes, from 1979 to 2018, the water vapor content in Central Asia showed a weak decreasing trend, with obvious regional differences in the rate of change. Water vapor content in the surrounding areas of the Aral Sea decreased significantly, whereas in most of the areas of the Xinjiang and Tianshan Mountains, it increased significantly. Zonal transport is the main mode of water vapor transport in Central Asia, compared with the relatively weak meridional transport. Large differences were found in the water vapor budget over different regions; the water vapor transport tended to decrease in the western and northern boundaries and increased in the eastern and southern boundaries. Water vapor revenue and expenditure showed an increasing trend in northwestern Central Asia, southern Central Asia, the Pamir Plateau, and the Tianshan Mountains and a decreasing trend in northern Central Asia and most of Xinjiang. In contrast to the change in water vapor transport, the precipitation in Central Asia increased from 1979 to 2018, with an increase of 4.14 mm·(10a)-1 and a large interannual fluctuation. The significant increasing trend of precipitation is distributed in northern Central Asia and most of the Xinjiang and Tianshan Mountains, whereas there was a significant decreasing trend in northwestern and southern Central Asia. The actual evaporation in Central Asia showed a slight increasing trend, increasing significantly in the northern part of Central Asia, the Tianshan Mountains, and Pamir but decreasing significantly in the Caspian Sea area, Aral Sea, southern Central Asia, and southern Xinjiang. In terms of seasonal variation, the temporal and spatial distribution of seasonal and annual variations of water cycle elements was generally consistent. The results of our analysis contribute to a better understanding of the evolution and mechanism of the atmospheric water cycle in the arid regions of Central Asia.
Subjects: Geosciences >> Geography submitted time 2022-12-12 Cooperative journals: 《干旱区科学》
Abstract： Vegetation growth status is an important indicator of ecological security. The Tarim River Basin is located in the inland arid region of Northwest China and has a highly fragile ecological environment. Assessing the vegetation net primary productivity (NPP) of the Tarim River Basin can provide insights into the vegetation growth variations in the region. Therefore, based on the Google Earth Engine (GEE) cloud platform, we studied the spatiotemporal variation of vegetation NPP in the Tarim River Basin (except for the eastern Gobi and Kumutag deserts) from 2001 to 2020 and analyzed the correlations between vegetation NPP and meteorological factors (air temperature and precipitation) using the Sen slope estimation method, coefficient of variation, and rescaled range analysis method. In terms of temporal characteristics, vegetation NPP in the Tarim River Basin showed an overall fluctuating upward trend from 2001 to 2020, with the smallest value of 118.99 g C/(m2•a) in 2001 and the largest value of 155.07 g C/(m2•a) in 2017. Regarding the spatial characteristics, vegetation NPP in the Tarim River Basin showed a downward trend from northwest to southeast along the outer edge of the study area. The annual average value of vegetation NPP was 133.35 g C/(m2•a), and the area with annual average vegetation NPP values greater than 100.00 g C/(m2•a) was 82,638.75 km2, accounting for 57.76% of the basin. The future trend of vegetation NPP was dominated by anti-continuity characteristic; the percentage of the area with anti-continuity characteristic was 63.57%. The area with a significant positive correlation between vegetation NPP and air temperature accounted for 53.74% of the regions that passed the significance test, while the area with a significant positive correlation between vegetation NPP and precipitation occupied 98.68% of the regions that passed the significance test. Hence, the effect of precipitation on vegetation NPP was greater than that of air temperature. The results of this study improve the understanding on the spatiotemporal variation of vegetation NPP in the Tarim River Basin and the impact of meteorological factors on vegetation NPP.
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