Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Farmland use intensity is an important factor to improve food production, alleviate the conflict between humans and land, and achieve sustainable agricultural development. Based on the farmland data obtained from high spatial resolution remote sensing images, this paper explores the farmland use intensity and its driving mechanism in the Yarlung Zangbo-Lhasa-Nyangqu River (YLN) region in 2000 and 2020 through a comprehensive evaluation index model. The results show that: (1) the degree of farmland use intensity in the YLN region has increased in the past 20 years, but the overall level is low. The farmland use intensity in 2020 was 38.2% higher than in 2000, which is mainly attributable to the increase in agricultural input, technological input, and the exploitation and utilization level. (2) There is a large difference in the change in farmland use intensity among different districts and counties; the high intensity areas migrated from east to west and increased in scope. The difference in farmland use intensity between east and west regions narrowed, and the number of low intensity districts and counties decreased. (3) The irrigation index, proportion of farmland area, and farmland quality have the most significant independent effects on the degree of farmland use intensity in the YLN, whereas socioeconomic factors, agricultural science and technology factors, and policy and environment factors interact with farmland resource endowment to increase the degree of impact on the farmland use intensity. Based on the above results, the following policy recommendations are proposed: the continuous promotion of agricultural science and technology innovation in the YLN region with a focus on regional differences, to realize sustainable development in high intensity areas and total factor inputs in low intensity areas, and facilitate the synergistic effects of agricultural policy and economy to coordinate and promote enhanced farmland use intensity in the YLN region.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Based on the daily minimum temperature measured at 42 meteorological stations in Qinghai Province from 1961 to 2019, the spatial and temporal evolution of different grades of cold days (extreme cold, extremely cold, severe cold, major cold, minor cold, light cold, slightly cold, cool) were analyzed. The results showed that: (1) From 1961 to 2019, the number of cold days in Qinghai Province gradually increased with decreasing levels, mainly dominated by slightly cold days. The total number of cold days showed an overall decreasing trend, with a significant rapid decrease occurring in 1995. The decrease in total cold days was mainly caused by the reduction in extremely cold days. After the climate abrupt change in 1997, the trends of severe cold, major cold, minor cold, light cold, slightly cold, and total cold days decreased, while the trend of extremely cold days increased. The trends of extreme cold and cool days decreased and increased respectively, with a distribution roughly equal. (2) Qinghai Province exhibits significant spatial differences in cold days, with the total number of cold days grad-ually increasing with altitude, and the trends of higher-level cold days are more pronounced. As the level of cold- ness decreases, the trends of increase and decrease develop towards lower latitudes and areas with relatively low-er altitudes. (3) The numbers of extreme cold, extremely cold, severe cold, light cold, slightly cold, and total cold days gradually decrease with increasing annual mean temperature, while the numbers of major cold, minor cold, and cool days gradually increase with increasing annual mean temperature. (4) Except for severe cold days, the numbers of other levels of cold days in Qinghai Province show persistence, and the downward trend will continue in the future, but the strength of persistence varies.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： This study aimed to reveal the effects of different habitats and substrates on seed germination and seedling growth of Malus sieversii after passing through digestive tract of cattle. A controlled experiment was set up in field based on the different habitats and substrates in which seeds were deposited after passing through the digestive tract of cattle. The three habitats were as follows: forest edges, gaps, and understory. The four treatments were as follows: W (seeds through digestive tract + intact feces), P (seeds through digestive tract + broken feces), T (seeds through digestive tract + soil), and control C (seeds not through digestive tract + soil). The results showed that: The seed germination rates, seedling survival rate, and seedling biomass of M. sieversii were significantly different (P<0.05) in different habitats and treatments. In the forest edge habitat, seeds germinated rate was higher in soil substrate compared to fecal substrate, while the gaps and understory habitats showed the opposite trend. Seedling survival rate was significantly higher in the forest edge and gaps habitats compared to the understory habitat. Under the same treatment, seedling biomass was higher in the forest edge compared to the gaps, and higher in the gaps compared to the understory. Within the same habitat, seedling biomass from fecal substrate in forest edge and gap habitats surpassed that of soil substrate. The study revealed that the heterogeneity of habitat and substrate is the main reason that affects the seed germination and seedling establishment of M. sieversii after passing through digestive tract of cattle.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： The effects of water, salt, and nitrogen (N) regulation on changes in the soil water, transport of salt nutrients, and growth indices and yield of cotton (Gossypium hirsutum) were analyzed under drip irrigation covered by film. A two-year three-factor full-combination field experiment was conducted to study the effects of three levels of irrigation (W1: 2700 m3·hm−2, W2: 3600 m3·hm−2, and W3: 4500 m3·hm−2), salinity (S1: 3 dS·m−1, S2: 6dS·m−1, and S3: 9 dS·m−1), and N (F1: 105 kg·hm−2, F2: 210 kg·hm−2, and F3: 315 kg·hm−2). The effects of different combinations of water-salt-nitrogen on soil moisture, salinity, N distribution, plant growth, and yield were investigated. The results showed the following: the soil moisture was mainly located in the 30-40 cm soil layer, and the water content of different soil depths essentially first increased and then decreased. The average water content of the 0-40 cm soil layer in the bud and boll stages of S3F3W1 and S2F3W1 increased by 1.3%-21.8% compared with that of S1F3W1, and the average water content of the combination of S1F3 increased by 1.39%-13.83% compared with those of S1F2 and S1F1 under the same amount of irrigation. The soil salinity tended to decrease and then increase during the fertile period. The S1 treatment increased and then decreased the soil salinity as N application increased, and the soil salinity in S2 and S3 decreased as the N application increased. The N content was significantly higher with the F3 treatment than F1 or F2. In the W2 and W3 treatments, N slowly accumulated in the 40-60 cm soil layer, and the N content was significantly higher with the S1 treatment than S2 or S3. The soil moisture, salinity, and N content interacted; under appropriate soil moisture and N conditions, lower soil salinity enabled the plants to utilize nutrients more efficiently, which facilitated their growth, and thus enhanced yield. To obtain high economic benefit, the recommended rate of irrigation for low and medium saline soils is 3600 m3·hm−2 and the rate of N is 210 kg·hm−2. For highly saline soils, the recommended rate of irrigation is 4500 m3·hm−2 and the rate of N is 315 kg·hm−2. This study provides a theoretical basis to explore the mechanism of water and salt nutrient transport and the efficient use of water and fertilizer in cotton farmland ecosystems under multiyear drip irrigation under a membrane in arid areas.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： This study aimed to clarify the carbon sequestration capacity and its change mechanisms in the dry- lands of China. The study used the AI index to delineate the extent of drylands. Based on the MODIS Vegetation Gross Primary Productivity (GPP) dataset, the temporal and spatial characteristics of vegetation carbon sequestra- tion capacity in China’s drylands from 2001 to 2020 were investigated. This investigation considered meteorolog- ical data, including temperature, precipitation, vapor pressure deficit (VPD), soil water content, and human activi- ties such as land use. The results reveal the following: (1) Over the 20-year period, GPP in China’s drylands ele- vated significantly in 64.72% of the regions. (2) Temperature had the lowest impact on GPP, with a relative contri- bution rate of 21.7%. Precipitation and soil water content emerged as the dominant factors driving GPP growth, with their combined contribution rate exceeding 55%. As drought intensified, the effect of water stress gradually strengthened. In different vegetation types, except for mixed forests and alpine vegetation, precipitation was the most critical climate factor influencing GPP changes. (3) Differences in soil and landform types were the domi- nant factors influencing the spatial variation of GPP. Moisture and land use type factors also played important roles, with the explanatory power of the interaction between any two factors exceeding that of a single factor. The interaction between soil type and the other factors was particularly remarkable. The study’s findings hold essen- tial theoretical implications for a deeper understanding of the evolution characteristics of carbon sinks in arid eco- systems in China and their response mechanisms to external environmental factors.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： The construction and optimization of an ecological network is an effective way to prevent landscape fragmentation and ensure regional ecological security. In this study, the Lanzhou-Xining urban agglomeration was selected as the research area. Using the adaptive cycle as the theoretical basis, coupled with the granularity inverse method and morphological spatial pattern analysis, the ecological sources were identified, and the comprehensive“ potential-connectivity-resilience ”ecological resistance surface was established. The circuit theory was applied to determine the vital ecological nodes and corridors. On this basis, an ecological network was constructed and optimization strategies were proposed. The results showed that the spatial distribution of ecological sources was uneven and fragmented, covering a total area of 4147.84 km2. As a whole, the resistance of the study area was characterized by a “high in the west and low in the east” trend, decreasing from the main city to surrounding areas. In total, 40 ecological corridors with a total length of 2278.59 km were extracted and distributed in the central part of the study area. Similarly, 24 ecological pinch points were extracted, primarily distributed in major river corridors and ecological sources; 25 ecological barrier points were identified, mostly located in ecological corridors. The structural indices of the ecological network α, β, and γ were 0.60, 2.00, and 0.74, respectively. By adding 12 stepping-stone patches, these indices increased by 18.33%, 14.00%, and 9.46%, respectively. These results can provide a references point for land space development and ecological security maintenance in the Lanzhou Xining urban agglomeration.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： The movement characteristics of barchan dunes along the southern edge of the Taklamakan Desert reveal wind-sand transport features and geomorphological evolution processes, which are of great significance for the systematic prevention of sand and dust disasters in the region. This study used satellite remote sensing images and meteorological reanalysis data to analyze the morphological changes and moving features of six barchan dune groups along the southern edge of the Taklamakan Desert from 2012 to 2022. The results showed that (1) the average moving speed of barchan dunes within the study area was 6.86 m·a−1, and the moving direction was consistent with the prevailing wind direction in the corresponding region; (2) the association between the morphological parameters of barchan dunes within the area was complex; (3) the movement of barchan dunes is jointly influenced by the wind energy environment, topography, climatic conditions, and vegetation coverage, of which the dune height, underlying surface vegetation coverage, average annual rainfall, and surface temperature were negatively correlated with dune moving speed, and these negative correlations were significantly optimized after regional classification; (4) the average sand transport rate in the study area was 77120.5 kg·m−1·a−1, and it was influenced by the underlying surface conditions and the wind energy environment within the region, which provides an important reference for optimizing sand prevention and control measures. The study results reflect the complexity of the moving pattern of the barchan dunes, and the degree of impact varied with the presence of different geographical environmental factors, which necessitates field-specific analysis. Moreover, the dynamic changes in morphological parameters during the evolution of dunes reveal the internal mechanism of dune migration, providing substantial data for studying the evolution characteristics of dunes and a scientific basis for wind prevention and solidifying work and land planning.
Subjects: Geosciences >> Geography submitted time 2024-07-11 Cooperative journals: 《干旱区地理》
Abstract：选取新疆8个辐射气象观测站1961—2022年逐日总辐射观测资料，分析新疆区域地面总辐射变化特征，利用风速、气温、湿度和露点温度等资料构建太阳能资源评估典型气象年挑选方法（Sandia法），对比分析1961—1990年、1971—2000年、1981—2010年、1991—2020年4个标准气候态下Sandia方法选取典型代表年的差异。结果表明：（1）1961—2022年北疆地区地面总辐射呈先减少后增加的趋势，南疆和东疆持续减少但1990年代以后减少趋势放缓，秋、冬季辐射减少速率明显大于春、夏季。（2）Sandia方法选取的4个标准气候态下典型气象年总辐射年值与平均值接近，相对误差介于±3%之间。（3）随着气象要素的变化，Sandia方法选取典型气象年总辐射与平均值的绝对误差在增大，北疆站点不同时期选取典型月总辐射与同期月均值的差异明显小于南疆和东疆，与北疆总辐射年际变化小于南疆和东疆的结果一致。（4）新疆区域月总辐射的高值时段集中出现在6—7月，各站1—3月总辐射普遍大于10—12月。（5）Sandia法挑选典型月与月平均值的差异存在较大波动性，且1981—2000年、1991—2020年波动幅度明显大于之前2个时期，表明随着气候要素的变化，典型代表年的不确定性在增加。
Subjects: Geosciences >> Geography submitted time 2024-07-11 Cooperative journals: 《干旱区地理》
Abstract：利用西藏高原38个气象站1981—2020年逐日气象观测资料及1970—2000年30 s空间分辨率气候数据，对人体舒适度指数（ICHB）及高原人体舒适度指数（PICHB）时空变化特征进行分析。研究表明：（1）西藏高原近40 a ICHB呈显著上升趋势，整个西藏高原年ICHB升高率为0.76·(10a)-1，各气候区年ICHB升高率为(0.57~0.98)·(10a)-1。季ICHB升高率在时间上表现为冬季>秋季>春季>夏季。（2）年ICHB和季ICHB的升高率在空间上表现为西部>北部>东北部>东南部>中部、南部边缘。（3）PICHB空间上表现为寒冷特不舒适、重度高原反应的区域主要分布在北部、西部及东北部的高山上；冷不舒适、重度高原反应的区域主要分布在北部、中部及南部边缘的高山上；冷不舒适、中度高原反应的区域主要分布在北部、中部和南部边缘等区域的较低海拔地区；凉较不舒适、轻度高原反应的区域主要分布在东南部和南部边缘地区；不冷不热舒适、无高原反应的区域主要分布在错那县南部和墨脱县南部。随着西藏高原近40 a 和未来气候“暖湿化”的变化趋势，各地月ICHB、季ICHB、年ICHB明显提高，PICHB也发生相应的变化，均向着舒适度升高的方向发展。
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Seed germination and the seedling growth of sand-fixing plants are decisive aspects of land desertifica- tion management, and soil moisture is the main limiting factor affecting these aspects. In this study, we compared and analyzed the seed germination of three sand-fixing plants under different moisture gradients (4%, 6%, 8%, 10%, 15%, 20%, and 25%) in an indoor potting experiment using Hedysarum scoparium, Caragana korshinskii, and Artemisia desertorum to investigate the response of seed germination and seedling growth of sand- fixing plants to changes soil in moisture. The results showed that: (1) significant differences (P<0.05) were observed in the seed germination characteristics of the three sand-fixing plants as the soil moisture increased. The germina- tion rates tended to increase and then decrease as the soil moisture increased. C. scoparium had the highest germi- nation rate at 15% and 20% soil moisture (83.00% in both); C. korshinskii had the highest germination rate at 10% soil moisture (73.00% ); and the seed germination rate of A. desertorum reached the maximum value of 77.50% at 15% soil moisture, and then slowly decreased, although the change was not significant. (2) The leaf ar- ea and root length of the three plants showed tended to first increase and then decrease as the soil moisture in- creased, and the specific leaf area and root:crown ratio tended to decrease and then increase. (3) The highest bio- mass of C. scoparium, C. korshinski, and A. desertorum seedlings was 0.0733 g, 0.1142 g, and 0.0363 g at 10%, 8%, and 20% soil moisture, respectively, and the aboveground biomass was significantly higher than the below- ground biomass (P<0.05), although the allocation of belowground biomass by C. korshinski seedlings was higher than that of C. scoparium and A. desertorum. (4) The SOD activity, POD activity, CAT activity, Pro content, SS content, and Chl content of the three sand-fixing plants tended to increase and then decrease as the soil moisture increased, whereas the MDA content, membrane permeability, and relative water content tended to decrease and then increase. Based on the above results, it was concluded that the three sand-fixing plants of C. scoparium, C. korshinski, and A. desertorum had the best seedling growth at 15% , 8% and 8% soil moisture, respectively, through the analysis of the affiliation function method. Therefore, when these three sand-fixing plants are used for vegetation restoration, the changes in soil moisture caused by rainfall conditions should be fully considered in addition to the seeds’own traits to improve the seedling emergence rate and the success of seedling growth.
Subjects: Geosciences >> Geography submitted time 2024-07-11 Cooperative journals: 《干旱区地理》
Abstract：基于2015—2021年庆阳市空气污染和气象数据，利用变率统计分析庆阳市空气质量指数、首要污染物及其浓度变化特征，运用气候相似性原理和多因子综合评价并探究气象因子对污染物的作用与影响，并确立响应指标，为全市精准开展大气污染防治提供支撑。结果表明：（1）庆阳市空气质量优良率86.6%，空气质量指数年均为73，呈不明显上升趋势。首要污染物主要为PM10、PM2.5和O3 3种，且季节特征明显。2017年后SO2污染明显改善，但颗粒物与O3并发的复合型污染凸显，与当地气候、污染排放源有密切关系。（2）O3浓度夜间维持较高位，且以1.5 μg·m-3·a-1的年速率上升，气温对O3正效应显著，初夏气温高，降水量少是O3浓度升高和超标的主要驱动因子。（3）外源输送和供暖期本地排放造成秋末—冬春季的PM10和PM2.5超标。（4）PM10、PM2.5和O3超标日下的主要气象因子阈值特征不同。
Subjects: Geosciences >> Geography submitted time 2024-07-11 Cooperative journals: 《干旱区地理》
Abstract：人类活动对全球温度升高的促进作用愈加明显，如何科学衡量人类活动强度并探究其与地表温度的时空关联性成为当前研究热题。以关中地区为例，整合人口密度、地区生产总值、夜间灯光强度、建设用地面积比例、电量消耗5个指标表征人类活动强度，分析关中地区人类活动强度与地表温度时空变化规律，探究人类活动强度与地表温度关联性及其驱动作用。结果表明：（1）2001—2020年关中地区平均地表高温、低温区域分别呈现总体增大、减少的趋势，地表高温区域范围不断扩大。（2）2000—2020年关中地区的人类活动强度逐渐增加，特别是在各地级市的市辖区和主要居民点，高强度区域范围不断扩大，而低强度区域主要位于秦岭山区。（3）2000—2020年关中地区人类活动强度与地表温度呈显著正相关性和空间上的集聚性，正相关区域面积呈现增大趋势，主要由不显著及负相关转化为正相关区域，高-高类型集聚区主要分布在各城市主城区，低-低类型集聚区主要分布在秦岭山区。（4）影响地表温度的人类活动强度指标中，夜间灯光强度、人口密度、建设用地面积比例对地表温度的驱动作用最为显著；且夜间灯光强度与建设用地面积比例、人口密度与建设用地面积比例交互作用对地表温度的解释力最强。
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Using the InVEST model, the carbon storage in the Tarim River Basin was estimated over a long period, and the spatial--temporal variation characteristic were described using trend analysis, correlation coefficients, and band set statistics to explore the overall spatial--temporal correlation between climate change and carbon storage in the study area; in addition, quantitative analysis of was performed the attribution of carbon storage in different topographic locations with the help of partial least square method. The results showed that: (1) From 2002 to 2020, the overall carbon storage level in the Tarim River Basin was low, following a horseshoe-shaped distribution characteristic (“low in the middle and high in the periphery”), and overall followed an increasing trend. (2) Carbon storage and average annual temperature, potential evapotranspiration, and average annual precipitation in the study area had the characteristics of opposite spatial distribution rather than the same spatial distribution, and the spatial differentiation was obvious. (3) The overall influence of climate factors on carbon storage followed the order: potential evapotranspiration>average annual temperature>average annual precipitation. (4) The potential evapotranspiration is the most significant variable for the levels I, III, and IV topography in the Tarim River Basin, whereas the average temperature and average precipitation are the most significant variables for the levels II and Vtopography in the Tarim River Basin.
Subjects: Geosciences >> Geography submitted time 2024-07-11 Cooperative journals: 《干旱区地理》
Abstract：在全球变暖的影响下，全球水文气候发生深刻变化，而季风与非季风过渡带地区气候复杂多样，所以摸清该地区过去长期气候变化规律是亟待解决的问题。利用36 棵青海云杉（Picea crassifolia）的66个树轮样芯建立了季风与非季风过渡带典型地区（中国贺兰山地区）1798—2016年（219 a）的青海云杉树轮宽度年表，并且通过皮尔逊相关法分析了树轮宽度年表与该地气候因子的相关性。结果表明：（1）青海云杉径向生长与该地的年平均最低温（R2=0.638，P<0.001）关系密切，利用线性回归方程重建贺兰山1815—2016年年平均最低温序列，重建方程的缩减误差和有效系数分别为0.808、0.482。（2）重建的年平均最低温序列在19世纪整体气温偏低，与学术界公认的“小冰期”一致，到19世纪后期，气温逐渐回升，并且气温序列出现了显著的暖期和极暖年，气温在19世纪50和90年代以及20世纪90年代发生3次气温突变。（3）Morlet小波分析显示了6 a、21 a和46~56 a的周期性分布特征。南方涛动、太平洋十年涛动和大西洋多年代际涛动是这种周期性变化的驱动因素。（4）大尺度空间相关分析表明重建的气温序列对大尺度区域的气温变化具有较好的空间表征，如内蒙古大部和宁夏大部。进而重建的季风与非季风过渡带典型地区年平均最低气温序列揭示了该地的气候变化特征，为全球气候变化研究提供参考。
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： For this study of the physical and chemical properties and mechanical characteristics of soil in the distribution area of Xiazangtan super large scale landslide of the upper Yellow River, plants and soil samples at different positions of the landslide were collected, and the plant growth index, soil density, water content, root content, shear strength index, and nutrient element content were measured. Spearman’s correlation analysis was used to explore the vegetation types, physical and chemical properties of soil, and the shear strength characteristics of the root–soil composite system in different positions of the landslide. The number of plant species tended to increase as the altitude decreased, and the dominant herbaceous herbs were Stipa aliena, Oxytropis ochrocephala, and Artemisia desertorum. The pH of the soil in the distribution area of the landslide was neutral to alkaline. The contents of organic matter, total nitrogen, and total phosphorus change greatly at the trailing edge of the landslide, whereas the contents of total potassium, alkali-hydrolyzed nitrogen, and four other nutrients change greatly but do not show obvious variation. The water content of soil first increases and then decreases with the decrease in altitude, while the density of soil increases as the altitude decreases, increasing by 7.05% and 5.88%, respectively. The cohesion c value and root content of the root-soil composite system first increased and then decreased as the altitude decreased. In addition, Spearman correlation analysis showed that the cohesion c value of the root-soil composite system was negatively correlated with altitude, but positively correlated with root content, organic matter, and water content. The results of this study have practical significance for guiding the prevention and control of geological disasters such as soil erosion, and shallow landslide in the upper reaches of the Yellow River, from Longyang Gorge to Jishi Gorge.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Abstract: Given the difficulties in the field measurement of soil salinization in Xinjiang and the difficulty in quickly and broadly evaluating the potential hazards of soil salinization, this study considers cotton fields in the Aral Reclamation area of Xinjiang as the research object, and uses multispectral remote sensing image data from Sentinel-2 SR and Landsat-9 OLI to construct a high-dimensional data set by comprehensively integrating 20 spectral indices and combining spectral indices. The optimal feature subset is screened using the method of exhaustive feature combination and cross-validation, and the inversion accuracy of soil salinization is compared for four machine learning algorithms (i.e., XGBoost, random forest, deep neural network, and K-nearest neighbor) under different feature combinations. Simultaneously, the difference in accuracy between Sentinel-2 SR and Landsat-9 OLI remote sensing images in soil salinization inversion is analyzed. The results show that: (1) The model constructed based on XGBoost algorithm can achieve high-precision prediction of cotton field salinization, with R2 higher than 0.7359, MSE lower than 0.0415, and MAPE lower than 0.1285. (2) For both Sentinel-2 SR and Landsat-9 OLI image data, the prediction accuracy of the XGBoost model is significantly better than other three algorithms. (3) There is a specific feature combination that enables the XGBoost algorithm to achieve the highest prediction accuracy. (4) The KNN algorithm underestimates the degree of cotton field salinization as a whole, and the accuracy of Sentinel-2 SR image data in cotton field salinization prediction (R2 = 0.7282–0.8838) is better than that of Landsat-9 OLI image data. This study realizes the precise monitoring of soil salinization in cotton fields in the Aral Reclamation area of Xinjiang, which should provide an effective and timely technical reference for soil salinization control and prevention in cotton fields in reclamation areas.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Net Primary Productivity (NPP) is an essential indicator of the terrestrial carbon (C) cycle, which can reflect the carbon sink capacity of terrestrial ecosystems. In the face of China’s“double carbon”goal of“carbon peak”and“carbon neutrality,”improving the carbon sequestration capacity of the terrestrial ecosystems is one of the crucial ways. Due to its vast geographical area and considerable vegetation restoration potential, it is of great practical significance to evaluate the current situation of carbon sequestration in Xinjiang and explore the potential of carbon sequestration so as to respond positively and realize the national“double carbon”goal. This study combined the Carnegie Ames Stanford Approach (CASA) model with the land use, remote sensing, and meteorological (temperature, precipitation, and solar radiation) data, and NPP in Xinjiang from 2001 to 2020 for the simulation. The Sen-MK method was used to analyze the trend in NPP changes. Pearson correlation analysis was used to identify the relationship between NPP variations and climatic factors. Further, different land use and vegetation scenarios from 2001 to 2020, as well as the pattern of NPP variations under pure climate scenarios simulated by the Miami model, were used to derive the final maximum potential of NPP and the maximum increment of NPP in Xinjiang. The results showed that: (1) The NPP in Xinjiang showed an upward trend with fluctuations from 2001 to 2020; (2) Among the climatic factors, precipitation had the maximal impact on NPP in Xinjiang; (3)Among the primary land use types in Xinjiang, cultivated land had a large NPP which showed an increasing trend; (4) The increment potential of NPP in Xinjiang was 79.43 g C·m−2. This study can provide a reference for Xinjiang to respond to the national call for“carbon peak”and“carbon neutrality”and to implement ecological restoration and cultivated land protection measures.
Subjects: Mine Engineering Technology >> Other Disciplines of Mining Engineering submitted time 2024-07-08
Abstract： Broken coal and rock (BCR) are an important component medium of the caving zone in the goaf (or gob), as well as the main filling material of fault fracture zone and collapse column. The compaction seepage characteristics of BCR directly affect the safe and efficient mining of coal mines. Thus, numerous laboratory studies have focused on the compaction seepage characteristics of BCR. This paper first outlines the engineering problems involved in the BCR during coal mining including the air leakage, the spontaneous combustion, the gas drainage, and the underground reservoirs in the goaf. Water inrush related to tectonics such as faults and collapse columns and surface subsidence related to coal gangue filling and mining also involve the compaction seepage characteristics of BCR. Based on the field problems of BCR, many attempts have been made to mimic field environments in laboratory tests. The experimental equipment (cavity size and shape, acoustic emission, CT, etc.) and experimental design for the BCR were firstly reviewed. The main objects of laboratory analysis can be divided into compression tests and seepage test. During the compaction test, the main research focuses on the bearing deformation characteristics (stress-strain curve), pore evolution characteristics, and re-crushing characteristics of BCR. The seepage test mainly uses gas or water as the main medium to study the evolution characteristics of permeability under different compaction stress conditions. In the laboratory tests, factors such as the type of coal and rock mass, particle size, particle shape, water pressure, temperature, and stress path are usually considered. The lateral compression test of BCR can be divided into three stages, including the self-adjustment stage, the broken stage, and the elastic stage or stable stage. At each stage, stress, deformation, porosity, energy, particle size and breakage rate all have their own characteristics. Seepage test regarding the water permeability experiment of BCR is actually belong to variable mass seepage. While the experimental test still focuses on the influence of stress on the pore structure of BCR in terms of gas permeability. Finally, future laboratory tests focus on the BCR related coal mining including scaling up, long term loading and water immersion, mining stress path matching were discussed.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Reservoirs play a pivotal role in regional economic development and societal well-being. In recent years, Xinjiang has experienced frequent extreme precipitation events, posing significant challenges to reservoir safety. However, research on precipitation characteristics specific to Xinjiang's reservoirs remains limited, impeding scientific guidance for water resource utilization and reservoir management. Utilizing daily precipitation data from 1961 to 2022 and hourly precipitation data from 2009 to 2022 in the Xiagou Reservoir watershed of Yiwu County, Hami City, this study analyzed long-term variations in different time scales and precipitation levels. The findings indicate: (1) During the rainy season from 1961 to 2022, the average precipitation in the Xiagou Reservoir catchment area showed a weak increasing trend, and the number of days with no continuous precipitation showed a significant increasing trend. The total number of precipitation days and the maximum continuous precipitation days both show a significant decreasing trend. The increase in precipitation and the significant decrease in precipitation days may lead to further enhancement of precipitation intensity in the region. (2) The rainy season is mainly characterized by light rain, yet over the past 62 years, the number of light rain and moderate rain days has decreased while heavy rain and torrential rain days have increased. The highest proportion of rainstorm rainfall to the total rainfall in rainy season is close to 50.0%, and the increase of rainstorm rainfall is the main reason for the increase of rainfall in rainy season in Xiagou reservoir catchment area. (3) Daily precipitation displays a pattern of advancing high values as precipitation intensity strengthens. For instance, high values for light rain occur in the afternoon, moderate rain at midday, heavy rain in the morning, and torrential rain in the early morning. Except for torrential rain, high values for other precipitation levels are predominantly during the daytime. The daily variation curves for average precipitation intensity exhibit multiple peaks with significant differences. The relationship between cumulative precipitation frequency and cumulative precipitation amount is more closely associated with light and moderate rain than with precipitation intensity. Conversely, the relationship between average precipitation intensity and cumulative precipitation amount is more closely related to heavy and torrential rain than to cumulative precipitation frequency.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： From observational data of scattering coefficients, the mass concentrations of aerosols and pollutants, and meteorological elements, collected from July 9, 2020 to July 8, 2023 in Xilinhot, the characteristics of aerosol scattering coefficients—including the variation over time, probability density distribution, and correlation with different types of aerosols and meteorological impact factors—are studied. Consequently, the scattering coefficient levels are classified. The results show that: (1) the overall level of aerosol scattering is relatively low, but the transport of dust aerosol in spring and the high frequency of temperature inversions in winter and at night may increase aerosol scattering. (2) The smaller the aerosol, the higher the correlation between aerosols and scattering coefficients, with the correlation coefficients following the order BC>PM2.5>PM10, although seasonal differences are observed. In addition, NO2 is an important factor in increasing scattering in autumn, whereas SO2 contributes to scattering in summer, autumn, and winter. (3) The increases in correlation coefficients are considered as the contribution rates of current meteorological factors to scattering coefficients, with contribution rates of between 1% and 2%.
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