分类： 地球科学 >> 地理学 提交时间： 2023-02-02 合作期刊: 《干旱区地理》
摘要：叶如藏布流域冰川和冰湖众多，冰川融水是当地重要的淡水资源，是冰湖扩张的重要补给，冰湖溃决是当地潜在的自然灾害，因此分析该区域冰川和冰湖的现状与变化特征具有重要的现实意义。基于Landsat系列遥感影像，分析1990—2020年叶如藏布流域冰川和冰湖的分布与变化特征。结果表明：（1）近30 a来叶如藏布流域冰川面积整体呈退缩趋势，由1990年167.80 km2退缩到2020 年128.92 km2，共退缩38.88 km2，年均退缩率为0.77%·a-1，且研究区冰川主要分布在海拔
5800~6400 m之间，集中分布在5°~20°的坡度上。（2）与冰川变化趋势相反，研究时段冰湖整体表现为扩张趋势，由1990年5.72 km2增加到2020年8.81 km2，30 a共增加3.09 km2，年均增长率为1.80%·a-1。（3）冰湖主要分布在海拔5000~5600 m范围内，坡度在0~10°分布面积较多，表碛覆盖型冰川与非表碛覆盖型冰川对冰湖有着不同程度的影响。（4）1990—2017年叶如藏布流域温度与降水波动较大，温度整体呈上升趋势，降水量则波动下降，导致叶如藏布流域的冰川消融，冰湖扩张。通过上述研究以期为叶如藏布流域地区提供详细的冰川和冰湖面积分布与变化特征基础数据，为防灾减灾提供一定的支撑。
分类： 地球科学 >> 地理学 提交时间： 2023-02-02 合作期刊: 《干旱区地理》
摘要：叶如藏布流域冰川和冰湖众多，冰川融水是当地重要的淡水资源，是冰湖扩张的重要补给，冰湖溃决是当地潜在的自然灾害，因此分析该区域冰川和冰湖的现状与变化特征具有重要的现实意义。基于Landsat系列遥感影像，分析1990—2020年叶如藏布流域冰川和冰湖的分布与变化特征。结果表明：（1）近30 a来叶如藏布流域冰川面积整体呈退缩趋势，由1990年167.80 km2退缩到2020 年128.92 km2，共退缩38.88 km2，年均退缩率为0.77%·a-1，且研究区冰川主要分布在海拔
5800~6400 m之间，集中分布在5°~20°的坡度上。（2）与冰川变化趋势相反，研究时段冰湖整体表现为扩张趋势，由1990年5.72 km2增加到2020年8.81 km2，30 a共增加3.09 km2，年均增长率为1.80%·a-1。（3）冰湖主要分布在海拔5000~5600 m范围内，坡度在0~10°分布面积较多，表碛覆盖型冰川与非表碛覆盖型冰川对冰湖有着不同程度的影响。（4）1990—2017年叶如藏布流域温度与降水波动较大，温度整体呈上升趋势，降水量则波动下降，导致叶如藏布流域的冰川消融，冰湖扩张。通过上述研究以期为叶如藏布流域地区提供详细的冰川和冰湖面积分布与变化特征基础数据，为防灾减灾提供一定的支撑。
分类： 地球科学 >> 水文学 提交时间： 2022-01-21 合作期刊: 《干旱区地理》
基于Landsat系列影像、数字高程模型（DEM）等资料，采用遥感图像处理及目视解译方法，提取了朋曲流域1990—2020年冰川边界信息，研究了近30 a来朋曲流域冰川面积的分布、变化及其与气候变化的响应关系。结果表明：（1）1990—2020年研究区冰川面积持续缩小，冰川面积的退缩率为1.52 %·a-1，对比不同时段冰川退缩特征发现，研究时段朋曲流域冰川退缩加速。（2）1990—2020年冰川分布面积随海拔的升高呈先增加后减小趋势，5900~6100 m之间冰川分布面积最大。（3）1990—2020年各坡向冰川均表现为退缩趋势，其中南坡冰川退缩率最大，北坡最小。（4）与坡向类似，不同坡度等级的冰川也呈现退缩趋势，冰川退缩主要集中于15°~45°范围内，其中30°~35°之间冰川退缩速率较快。（5）综合分析区域的气温与降水数据可知，研究区冰川面积变化受气候条件的影响，气温上升、降水减少有可能是导致冰川退缩加速的主要原因，相比而言，前者对冰川退缩的影响更大。
分类： 地球科学 >> 地理学 提交时间： 2021-09-08 合作期刊: 《干旱区科学》
摘要：As the largest inland river basin of China, the Tarim River Basin (TRB), known for its various natural resources and fragile environment, has an increased risk of ecological crisis due to the intensive exploitation and utilization of water and land resources. Since the Ecological Water Diversion Project (EWDP), which was implemented in 2001 to save endangered desert vegetation, there has been growing evidence of ecological improvement in local regions, but few studies have performed a comprehensive ecological vulnerability assessment of the whole TRB. This study established an evaluation framework integrating the analytic hierarchy process (AHP) and entropy method to estimate the ecological vulnerability of the TRB covering climatic, ecological, and socioeconomic indicators during 2000–2017. Based on the geographical detector model, the importance of ten driving factors on the spatial-temporal variations of ecological vulnerability was explored. The results showed that the ecosystem of the TRB was fragile, with more than half of the area (57.27%) dominated by very heavy and heavy grades of ecological vulnerability, and 28.40% of the area had potential and light grades of ecological vulnerability. The light grade of ecological vulnerability was distributed in the northern regions (Aksu River and Weigan River catchments) and western regions (Kashgar River and Yarkant River catchments), while the heavy grade was located in the southern regions (Kunlun Mountains and Qarqan River catchments) and the Mainstream catchment. The ecosystems in the western and northern regions were less vulnerable than those in the southern and eastern regions. From 2000 to 2017, the overall improvement in ecological vulnerability in the whole TRB showed that the areas with great ecological improvement increased by 46.11%, while the areas with ecological degradation decreased by 9.64%. The vegetation cover and potential evapotranspiration (PET) were the obvious driving factors, explaining 57.56% and 21.55% of the changes in ecological vulnerability across the TRB, respectively. In terms of ecological vulnerability grade changes, obvious spatial differences were observed in the upper, middle, and lower reaches of the TRB due to the different vegetation and hydrothermal conditions. The alpine source region of the TRB showed obvious ecological improvement due to increased precipitation and temperature, but the alpine meadow of the Kaidu River catchment in the Middle Tianshan Mountains experienced degradation associated with overgrazing and local drought. The improved agricultural management technologies had positive effects on farmland ecological improvement, while the desert vegetation in oasis-desert ecotones showed a decreasing trend as a result of cropland reclamation and intensive drought. The desert riparian vegetation in the lower reaches of the Tarim River was greatly improved due to the implementation of the EWDP, which has been active for tens of years. These results provide comprehensive knowledge about ecological processes and mechanisms in the whole TRB and help to develop environmental restoration measures based on different ecological vulnerability grades in each sub-catchment.
分类： 地球科学 >> 地理学 提交时间： 2021-09-08 合作期刊: 《干旱区科学》
摘要：As the largest inland river basin of China, the Tarim River Basin (TRB), known for its various natural resources and fragile environment, has an increased risk of ecological crisis due to the intensive exploitation and utilization of water and land resources. Since the Ecological Water Diversion Project (EWDP), which was implemented in 2001 to save endangered desert vegetation, there has been growing evidence of ecological improvement in local regions, but few studies have performed a comprehensive ecological vulnerability assessment of the whole TRB. This study established an evaluation framework integrating the analytic hierarchy process (AHP) and entropy method to estimate the ecological vulnerability of the TRB covering climatic, ecological, and socioeconomic indicators during 2000–2017. Based on the geographical detector model, the importance of ten driving factors on the spatial-temporal variations of ecological vulnerability was explored. The results showed that the ecosystem of the TRB was fragile, with more than half of the area (57.27%) dominated by very heavy and heavy grades of ecological vulnerability, and 28.40% of the area had potential and light grades of ecological vulnerability. The light grade of ecological vulnerability was distributed in the northern regions (Aksu River and Weigan River catchments) and western regions (Kashgar River and Yarkant River catchments), while the heavy grade was located in the southern regions (Kunlun Mountains and Qarqan River catchments) and the Mainstream catchment. The ecosystems in the western and northern regions were less vulnerable than those in the southern and eastern regions. From 2000 to 2017, the overall improvement in ecological vulnerability in the whole TRB showed that the areas with great ecological improvement increased by 46.11%, while the areas with ecological degradation decreased by 9.64%. The vegetation cover and potential evapotranspiration (PET) were the obvious driving factors, explaining 57.56% and 21.55% of the changes in ecological vulnerability across the TRB, respectively. In terms of ecological vulnerability grade changes, obvious spatial differences were observed in the upper, middle, and lower reaches of the TRB due to the different vegetation and hydrothermal conditions. The alpine source region of the TRB showed obvious ecological improvement due to increased precipitation and temperature, but the alpine meadow of the Kaidu River catchment in the Middle Tianshan Mountains experienced degradation associated with overgrazing and local drought. The improved agricultural management technologies had positive effects on farmland ecological improvement, while the desert vegetation in oasis-desert ecotones showed a decreasing trend as a result of cropland reclamation and intensive drought. The desert riparian vegetation in the lower reaches of the Tarim River was greatly improved due to the implementation of the EWDP, which has been active for tens of years. These results provide comprehensive knowledge about ecological processes and mechanisms in the whole TRB and help to develop environmental restoration measures based on different ecological vulnerability grades in each sub-catchment.
分类： 地球科学 >> 地理学 提交时间： 2021-01-22 合作期刊: 《干旱区科学》
Durdiev KHAYDAR
CHEN Xi
HUANG Yue
Makhmudov ILKHOM
LIU Tie
Ochege FRIDAY
Abdullaev FARKHOD
Gafforov KHUSEN
Omarakunova GULKAIYR
摘要：High water consumption and inefficient irrigation management in the agriculture sector of the middle and lower reaches of the Amu Darya River Basin (ADRB) have significantly influenced the gradual shrinking of the Aral Sea and its ecosystem. In this study, we investigated the crop water consumption in the growing seasons and the irrigation water requirement for different crop types in the lower ADRB during 2004–2017. We applied the FAO Penman–Monteith method to estimate reference evapotranspiration (ET0) based on daily climatic data collected from four meteorological stations. Crop evapotranspiration (ETc) of specific crop types was calculated by the crop coefficient. Then, we analyzed the net irrigation requirement (NIR) based on the effective precipitation with crop water requirements. The results indicated that the lowest monthly ET0 values in the lower ADRB were found in December (18.2 mm) and January (16.0 mm), and the highest monthly ET0 values were found in June and July, with similar values of 211.6 mm. The annual ETc reached to 887.2, 1002.1, and 492.0 mm for cotton, rice, and wheat, respectively. The average regional NIR ranged from 514.9 to 715.0 mm in the 10 Irrigation System Management Organizations (UISs) in the study area, while the total required irrigation volume for the whole region ranged from 4.2×109 to 11.6×109 m3 during 2004–2017. The percentages of NIR in SIW (surface irrigation water) ranged from 46.4% to 65.2% during the study period, with the exceptions of the drought years of 2008 and 2011, in which there was a significantly less runoff in the Amu Darya River. This study provides an overview for local water authorities to achieve optimal regional water allocation in the study area.
分类： 地球科学 >> 地理学 提交时间： 2020-06-02 合作期刊: 《干旱区地理》
摘要： 人口分布是在一定时间、一定地域范围人口在空间上的表现，它会受社会、经济、自然和政策等多种因素影响，甘肃省人口分布处于不平衡状态。以甘肃省86个县域及嘉峪关市共87个研究单元为对象，常住人口数据为基础，对研究区1990-20巧年之间人口的分布特征、密度变化、分布结构指数、基尼系数、重心迁移等时空格局变化进行了分析。以县域为研究单元，选取12个自然和社会经济因素，利用偏最小二乘法(PLS)对影响甘肃省人口分布空间格局的因素进行分析。研究发现:(l)近25 a来甘肃省人口空间分布差异显著，形成“东南密集西北稀疏”格局;(2)从人口密度变化来看，相较于1990年，2015年甘肃省87个研究单元中，有67个县域属于增加类型,20个县域属于降低类型;}3)全省人口分布的均衡性发展态势在增强;}4)人口分布的重心逐渐向西北方向迁移;(5)甘肃省人口分布格局的形成受自然因素与社会经济因素的同时影响，但社会经济因素影响最大。
分类： 地球科学 >> 地球科学史 提交时间： 2018-09-18 合作期刊: 《干旱区科学》
摘要： Estimation of above-ground biomass is vital for understanding ecological processes. Since direct measurement of above-ground biomass is destructive, time consuming and labor intensive, canopy cover can be considered as a predictor if a significant correlation between the two variables exists. In this study, relationship between canopy cover and above-ground biomass was investigated by a general linear regression model. To do so, canopy cover and above-ground biomass were measured at 5 sub-life forms (defined as life forms grouped in the same height classes) using 380 quadrats, which is systematic-randomly laid out along a 10-km transect, during four sampling periods (May, June, August, and September) in an arid rangeland of Marjan, Iran. To reveal whether obtained canopy cover and above-ground biomass of different sampling periods can be lumped together or not, we applied a general linear model (GLM). In this model, above-ground biomass was considered as a dependent or response variable, canopy cover as an independent covariate or predictor factor and sub-life forms as well as sampling periods as fixed factors. Moreover, we compared the estimated above-ground biomass derived from remotely sensed images of Landsat-8 using NDVI (normalized difference vegetation index), after finding the best regression line between predictor (measured canopy cover in the field) and response variable (above-ground biomass) to test the robustness of the induced model. Results show that above-ground biomass (response variable) of all vegetative forms and periods can be accurately predicted by canopy cover (predictor), although sub-life forms and sampling periods significantly affect the results. The best regression fit was found for short forbs in September and shrubs in May, June and August with R2 values of 0.96, 0.93 and 0.91, respectively, whilst the least significant was found for short grasses in June, tall grasses in August and tall forbs in June with R2 values of 0.71, 0.73 and 0.75, respectively. Even though the estimated above-ground biomass by NDVI is also convincing (R2=0.57), the canopy cover is a more reliable predictor of above-ground biomass due to the higher R2 values (from 0.75 to 0.96). We conclude that canopy cover can be regarded as a reliable predictor of above-ground biomass if sub-life forms and sampling periods (during growing season) are taken into account. Since, (1) plant canopy cover is not distinguishable by remotely sensed images at the sub-life form level, especially in sparse vegetation of arid and semi-arid regions, and (2) remotely sensed-based prediction of above-ground biomass shows a less significant relationship (R2=0.57) than that of canopy cover (R2 ranging from 0.75 to 0.96), which suggests estimating of plant biomass by canopy cover instead of cut and weighting method is highly recommended. Furthermore, this fast, nondestructive and robust method that does not endanger rare species, gives a trustworthy prediction of above-ground biomass in arid rangelands.
分类： 生物学 >> 生态学 提交时间： 2018-01-10
摘要：The health risks associated with the consumption of rice may decrease if consumers use cooking practices which can reduce the concentrations of metal(loid)s and their bioaccessibility. The effects of cooking on the bioaccessibility of Cd and As in three contamination levels of rice were studied. The results indicated that cooking reduced bioaccessibility of Cd and As in rice. Cooking resulted in a significant increase in Cd and As concentrations in the residual fraction. Low volume cooking rice to dryness remove total Cd by about 10% for rice A and B, while middle or high volume water had no effect on Cd bioaccessibility in all rice types. In contrast, low volume cooking did not remove As, but a significant decrease was observed when cooking with middle or high volume water. This study provides information for a better understanding of more realistic estimation of metal(loid)s exposure from rice and the possible health risks.
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