Ecological problems and ecological restoration zoning of the Aral Sea

The Aral Sea was the fourth largest lake in the world but it has shrunk dramatically as a result of irrational human activities, triggering the "Aral Sea ecological crisis". The ecological problems of the Aral Sea have attracted widespread attention, and the alleviation of the Aral Sea ecological crisis has reached a consensus among the five Central Asian countries(Kazakhstan, Uzbekistan, Tajikistan, Kyrgyzstan, and Turkmenistan). In the past decades, many ecological management measures have been implemented for the ecological restoration of the Aral Sea. However, due to the lack of regional planning and zoning, the results are not ideal. In this study, we mapped the ecological zoning of the Aral Sea from the perspective of ecological restoration based on soil type, soil salinity, surface water, groundwater table, Normalized Difference Vegetation Index(NDVI), land cover, and aerosol optical depth(AOD) data. Soil salinization and salt dust are the most prominent ecological problems in the Aral Sea. We divided the Aral Sea into 7 first-level ecological restoration subregions(North Aral Sea catchment area in the downstream of the Syr Darya River(Subregion Ⅰ);artificial flood overflow area in the downstream of the Aral Sea(Subregion Ⅱ);physical/chemical remediation area of the salt dust source area in the eastern part of the South Aral Sea(Subregion Ⅲ);physical/chemical remediation area of severe salinization in the central part of the South Aral Sea(Subregion Ⅳ);existing water surface and potential restoration area of the South Aral Sea(Subregion Ⅴ);Aral Sea vegetation natural recovery area(Subregion Ⅵ);and vegetation planting area with slight salinization in the South Aral Sea(Subregion Ⅶ)) and 14 second-level ecological restoration subregions according to the ecological zoning principles. Implementable measures are proposed for each ecological restoration subregion. For Subregion Ⅰ and Subregion Ⅱ with lower elevations, artificial flooding should be carried out to restore the surface of the Aral Sea. Subregion Ⅲ and Subregion Ⅳ have severe salinization, making it difficult for vegetation to grow. In these subregions, it is recommended to cover and pave the areas with green biomatrix coverings and environmentally sustainable bonding materials. In Subregion Ⅴ located in the central and western parts of the South Aral Sea, surface water recharge should be increased to ensure that this subregion can maintain normal water levels. In Subregion Ⅵ and Subregion Ⅶ where natural conditions are suitable for vegetation growth, measures such as afforestation and buffer zones should be implemented to protect vegetation. This study could provide a reference basis for future comprehensive ecological management and restoration of the Aral Sea.

基于三维识别的中国干旱事件演变特征分析

中国是世界上受干旱影响最严重的国家之一,干旱频发给我国经济社会发展和生态环境造成严重影响。为分析近40 a干旱事件的时空特征,本文结合三维聚类算法,从干旱事件时空联动的本质出发,识别中国1981—2020年间干旱事件并定量分析干旱事件的时空动态演变过程。主要结论如下:三维聚类算法能有效识别干旱事件及其动态变化过程。中国1981—2020年间发生持续2个月及以上的干旱事件102场,空间上,干旱事件空间轨迹倾向于自东向西发展;时间上,干旱事件时间重叠度较高,长历时干旱多具有多峰特点。此外,覆盖范围广且严重度高的干旱事件集中发生于2005—2010年。本文结论有助于发现中国干旱事件的时空演化规律,为我国干旱监测和干旱风险管理提供科学参考。

多行人轨迹多视角三维仿真视频学习预测法

多行人轨迹预测是城市地理信息系统与智能交通融合的关键因素之一。针对现有行人轨迹预测方法训练数据量不足、标注难、对多视角场景轨迹预测精度低等问题,本文提出一种多行人轨迹多视角三维仿真视频学习预测方法。首先,通过仿真模拟器生成所需多视角行人轨迹标注数据,利用凸函数组合原始视角对抗轨迹和选定的多视角轨迹,生成增强对抗轨迹,接着使用检测跟踪算法对行人特征信息进行编码;然后,将增强轨迹和编码信息作为图注意力循环神经网络的特征输入,对行人交互信息建模;最后,通过位置解码器对行人轨迹进行解码并提取行人运动特征,完成多行人轨迹预测。本文方法在ETH/UCY固定视角数据集上的ADE和FDE精度分别为0.41和0.82。在ActEV/VIRAT和Argoverse多视角数据集上的ADE精度为17.74和65.4,FDE精度为34.96和172.8。

基于空间异质性的库鲁斯台草地退化

以库鲁斯台草原为研究区,基于1990—2020年Landsat数据,选择归一化植被指数(NDVI)及空间异质性作为草地退化的遥感监测指标,对库鲁斯台草地退化状况进行评估。结果表明:1)1990—2020年,研究区中部NDVI呈上升趋势,而边缘区域呈下降趋势;草地空间异质性上升的区域主要集中在研究区中部及西南部地区,北部和南部则以下降为主。2)草地退化的监测表明,约54%的草地出现退化,35%的草地得到了改善,10%的草地植被恢复。3)温度和降水对草地空间异质性的年际变化影响较小,对NDVI影响较大,降水量是影响库鲁斯台草原NDVI时间动态的主要因素。

Sentinel-2和ICESat-2密集时序数据反演浅平型内陆湖泊水量变化

干旱区内陆尾闾湖泊由于湖盆地形浅平、岸线复杂等特点,采用传统的水位-面积关系法难以反演高精度的水量变化信息。本文提出了一种基于密集时序ICESat-2和Sentinel-2数据反演浅平型内陆湖泊湖盆地形和重建水量时序的方法。本文方法利用浅平型湖泊季节性变化显著的特性,筛选和计算不同时期湖盆内非水面区域的所有ICESat-2激光光子点的高程信息,并根据水面等高的特性内插得到Sentinel-2不同时相水面线的高程信息,在此基础上通过这些加密的高程点构建高精度湖盆地形信息,并结合水面时序重建湖泊的水量变化。以新疆塔里木河尾闾台特玛湖为试验区,基于132期Sentinel-2卫星影像和28个时相的ICESat-2激光脉冲数据,重建了2016—2022年的湖泊水量时序。结果表明,本文方法获取的湖盆地形高程中误差为0.103 m,可为无资料浅平型湖泊水量信息的时序重建提供一种思路。

Evaluation of the water conservation function in the Ili River Delta of Central Asia based on the InVEST model

The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020,and investigated the main driving factors(precipitation,potential evapotranspiration,land use/land cover change,and inflow from the Ili River)of the water conservation variation based on the linear regression,piecewise linear regression,and Pearson's correlation coefficient analyses.The results indicated that from 1975 to 2020,the water yield and water conservation in the IRD showed a decreasing trend,and the spatial distribution pattern was"high in the east and low in the west";overall,the water conservation of all land use types decreased slightly.The water conservation volume of grassland was the most reduced,although the area of grassland increased owing to the increased inflow from the Ili River.At the same time,the increased inflow has led to the expansion of wetland areas,the improvement of vegetation growth,and the increase of regional evapotranspiration,thus resulting in an overall reduction in the water conservation.The water conservation depth and precipitation had similar spatial distribution patterns;the change in climate factors was the main reason for the decline in the water conservation function in the delta.The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash,promoted vegetation restoration,and had a positive effect on the water conservation;however,this positive effect cannot offset the negative effect of enhanced evapotranspiration.These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.

中亚高山冰川表面高程变化时序重建

中亚高山冰川区地形复杂,站点观测和传统实地测量范围十分有限。卫星激光测高技术可实现大范围冰川表面高程变化监测。以2003-2009年ICESat激光测高数据为数据源,参考2000年的SRTM高程数据,建立冰川区点云去噪及其精度优化算法和多尺度冰川区表面高程时空变化分析模型,并分析了2003-2009年间中亚山区整体与各分区冰川表面高程时序变化。结果表明:中亚高山冰川区的冰川表面平均高程整体呈下降趋势,表现出明显的区域差异。其中,2003-2009年中亚冰川表面高程总体下降了9.59±1.89 m;Ⅰ区(即西藏和青海南部)的冰川表面高程下降了6.51±2.9 m;Ⅱ区(即新疆、青海北部和甘肃部分地区)下降了7.87±5.03 m;Ⅲ区(即中国境外,中亚地区的部分国家)下降了9.81±5.1 m,且监测到2004-2005年冰川表面高程上升。本研究方法对冰川区点云类高程脚点监测具有一定的通用性,但对基准DEM的依赖度较高。

1990-2019年咸海水量平衡及其影响因素分析

咸海地处中亚,气候和人类的双重影响下湖面急剧萎缩引发区域生态危机,定量解析其水量平衡互动关系及影响因素对咸海地区水资源管理和生态保护有重要意义.基于19902019年密集时序Landsat影像、T/P卫星、Jason1/2测高卫星及咸海数字测深模型(DBM),提取近30年咸海面积、水位变化信息,重建咸海水位面积库容曲线,探明咸海水量变化特征;建立水量平衡模型,定量分析研究区水量平衡要素变化及时空差异,探讨其互动关系与影响机制.结果表明:(1)19902019年间,咸海水量减少了2271.6×10^(8) m^(3)(约75.15%),年平均变化率达-78.3×10^(8) m^(3)/a;南咸海水量变化趋势与咸海整体基本一致,北咸海除1999年出现了极小值外,其余年份水量变化趋势均呈波动上升状态,至2019年水位已恢复至1984年水平.(2)1990s以来,南、北咸海水量平衡结构变化时空差异显著,阿姆河入湖径流量呈波动减少趋势,随着咸海持续退缩水体蒸发不断减小,区域水量支出收入比由1990年的2.46降低到2015年的0.87;近年来丰水年份南咸海地下水可由亏损转化为盈余状态,水域变化进入相对平缓的状态.北咸海入湖径流量波动增加,蒸散发随水域面积增加而增加,1990s初以来水量收入超过水量支出,区域地下水盈余,湖泊水位不断抬升.(3)湖区尺度上,入湖径流量和水域蒸发量是咸海水量变化的主导因素.流域尺度上,气候变化与人类活动共同影响咸海入湖水量,南咸海入湖水量与阿姆河上游来水、流域耕地面积显著相关,而北咸海入湖水量主要与锡尔河上游来水相关.

2013—2020年塔里木河流域胡杨林生态恢复成效评估

生态输水是塔里木河流域退化胡杨林生态恢复的主要措施,及时监测和准确评估其恢复成效是优化输水策略、完善胡杨林修复体系的关键。以2013年以来8个胡杨林区为研究对象,基于中高分辨率遥感数据监测不同胡杨林区生态输水前后植被面积、长势及植被覆盖度的时序变化,探讨胡杨林恢复与生态输水的关系。结果表明:(1)2016年以来整个流域累计漫溢水面为2172.96 km^(2),占林区总面积的4.39%,主要分布在输水通道两侧及末端10 km范围内。(2)输水前后林区植被整体呈现由退化到恢复的转变,林区生态恢复水平与年最大漫溢面积显著正相关。(3)生态恢复成效评估表明,生态恢复最显著的区域是塔里木河中上游和叶尔羌河下游的夏马勒林场,但整个流域远离输水通道的胡杨林仍有退化趋势。合理规划输水通道建设,扩大胡杨林区的受水范围是退化胡杨林生态恢复的关键。

林农间作模式下和田绿洲特色林果结构遥感信息提取

实时准确地获取林农间作模式下的果树结构信息对推进新疆特色林果业的提质增效,增加农民收入,稳定脱贫攻坚成果,实现乡村振兴具有重要意义。该研究以新疆和田绿洲林农间作区为研究对象,提出一种综合高分遥感数据的纹理和光谱特征以及中分遥感数据的时序物候特征的果树提取方法。基于GF-2遥感数据利用面向对象方法提取高分辨率的林田地块空间信息;基于多时相Sentinel-2遥感数据构建植被归一化指数(Normalized Difference Vegetable Index,NDVI)时间序列产品,并依据果树物候特征建立决策树模型,提取间作核桃、纯核桃、枣树和葡萄4种类型;最后将多时相的分类结果与高分的林田地块叠加,获取和田绿洲特色林果作物分布信息。该方法对2020年和田绿洲核桃、枣树和葡萄提取结果的用户精度和总体分类精度均在90%以上,Kappa系数为94.95%,能够满足县市级尺度的林果遥感监测精度需求。基于遥感提取的和田绿洲主要林果作物面积为4.28×10^(5)hm^(2),以核桃(间作和纯核桃)为主,间作核桃面积占比63.80%,该方法可为林农间作立体种植模式下的果树类型和面积精确信息提取研究提供参考和借鉴。

1962—2019年锡尔河-咸海三角洲湿地时空变化及驱动因素

咸海周边环境变化对中亚干旱区生态稳定有重要影响,研究锡尔河-咸海三角洲湿地演变对认识流域生态环境变化、实施生态修复等具有重要意义。基于多源遥感数据采用面向对象分层提取法方法,分析1962—2019年锡尔河下游三角洲湿地的时空变化特征,并结合咸海变化、耕地变化、河流水量和水利工程建设等探讨近60a湿地变化的驱动因素。研究表明:①近60 a在咸海持续萎缩的情况下,锡尔河下游三角洲湿地呈现先减小后增加的变化趋势,其中1962—1980年、1981—1991年和1992—2019年3个阶段的变化率分别为-38.29 km 2/a、193.35 km 2/a和14.36 km 2/a;②湿地变化有明显的空间差异,锡尔河南、北2个入湖口区的湿地自1980年以来向咸海湖区扩张明显,耕地混合区的湿地自1991年以来向河道两侧扩张;③1962年后在入三角洲径流量总体减少的趋势下,灌渠建设和生态用水配置是三角洲湿地面积增加的主要原因,间接导致咸海入湖水量减少,咸海快速萎缩。锡尔河三角洲湿地恢复与咸海干涸形成了明显的生态反差,不利于咸海周边生态的整体恢复。

阿姆河流域耕地变化及水土匹配特征分析

基于中亚阿姆河流域4个分区1990—2015年间土地利用变化和水资源等数据,运用耕地变化速率、洛伦兹曲线和基尼系数法以及水土资源匹配系数对阿姆河流域耕地变化和水土匹配状况进行了综合分析。结果表明:1990—2015年阿姆河流域耕地以146.74 km^(2)/a的速度在扩张,且各时期、各分区扩张的速度不同;在不考虑咸海来水不断减少、生态持续恶化的前提下,绿洲区匹配状况属比较公平和相对合理状况;阿姆河流域水土资源空间分布存在明显的错位现象;全流域生态用水被农业用水严重挤占,阿姆河流域灌溉面积、灌溉用水量成为影响咸海水量及面积变化的重要因素,是一种不可持续的用水方式。

1995-2020年新疆巴里坤湖面积时序变化及归因

巴里坤湖是天山东部山间内陆封闭型湖泊,了解巴里坤湖的演变特征对于开展湖泊保护与生态环境治理具有重要意义。利用308景Landsat系列和Sentinel 2遥感影像提取1995—2020年湖泊水面的时间序列,并结合巴里坤气象站资料以及从遥感影像上提取的耕地面积数据,分析湖泊在气候变化与人类活动影响下的变化趋势。结果表明:湖泊变化经历了2个阶段:1995—2006年萎缩,从年均值57.33 km^(2)下降到35.53 km^(2),下降速率1.98 km^(2)·a^(-1),萎缩35.79%;2006—2020年扩张,从年均值35.53 km^(2)上升到46.59 km^(2),上升速率0.79 km^(2)·a^(-1),扩张31.12%。多年湖泊面积的月变化统计表明:湖泊在5月达到最大值(73.09±21.01)km^(2),11月达到最小值(43.90±16.97)km^(2)。影响因素:1995—2006年,降水变化幅度较小,农业用水与蒸发量增加是巴里坤湖萎缩的主要原因;2006年后,巴里坤县出台多种湿地保护措施,耕地面积扩张趋势得到控制,降水显著增加与蒸发量减少成为湖泊面积扩张的主要原因。

咸海流域陆地水储量时空变化研究

采用2002—2016年GRACE(Gravity recovery and climate experiment)重力卫星JPL-RL06M数据分析咸海流域陆地水储量变化(Terrestrial water storage change,TWSC)时空变化特征,并结合CRU TS4.03气象数据、GLDAS-Noah地表蒸散发数据和高精度土地利用数据探究气候变化与人类活动对陆地水储量的影响。结果表明:(1)2002—2016年咸海流域陆地水储量变化呈现-3.20 mm·a^(-1)下降趋势,春、夏季陆地水储量呈盈余态势,秋、冬季呈现亏损状态;水储量变化在空间上表现为中部和东部盈余,周边亏损的特征。(2)2002—2016年咸海流域降水量呈-1.14 mm·a^(-1)下降趋势,地表温度呈0.11℃·a^(-1)上升趋势;相比气温,水储量变化与降水量相关性更强。(3)2000—2015年,咸海流域耕地面积小幅增加1.65×10^(4) km^(2),水域面积减少;农作物耗水和灌溉需水的增加加剧了咸海流域水量支出,咸海流域蒸散发呈21.63×10^(8) m^(3)·a^(-1)增加态势,在空间上与陆地水储量变化的相关系数最高达0.74,是影响陆地水储量变化的主要因素之一。

Simulating hydrological responses to climate change using dynamic and statistical downscaling methods: a case study in the Kaidu River Basin, Xinjiang, China

Climate change may affect water resources by altering various processes in natural ecosystems. Dynamic and statistical downscaling methods are commonly used to assess the impacts of climate change on water resources. Objectively, both methods have their own advantages and disadvantages. In the present study, we assessed the impacts of climate change on water resources during the future periods (2020–2029 and 2040–2049) in the upper reaches of the Kaidu River Basin, Xinjiang, China, and discussed the uncertainties in the research processes by integrating dynamic and statistical downscaling methods (regional climate models (RCMs) and general circulation modes (GCMs)) and utilizing these outputs. The reference period for this study is 1990–1999. The climate change trend is represented by three bias-corrected RCMs (i.e., Hadley Centre Global Environmental Model version 3 regional climate model (HadGEM3-RA), Regional Climate Model version 4 (RegCM4), and Seoul National University Meso-scale Model version 5 (SUN-MM5)) and an ensemble of GCMs on the basis of delta change method under two future scenarios (RCP4.5 and RCP8.5). We applied the hydrological SWAT (Soil and Water Assessment Tool) model which uses the RCMs/GCMs outputs as input to analyze the impacts of climate change on the stream flow and peak flow of the upper reaches of the Kaidu River Basin. The simulation of climate factors under future scenarios indicates that both temperature and precipitation in the study area will increase in the future compared with the reference period, with the largest increase of annual mean temperature and largest percentage increase of mean annual precipitation being of 2.4°C and 38.4%, respectively. Based on the results from bias correction of climate model outputs, we conclude that the accuracy of RCM (regional climate model) simulation is much better for temperature than for precipitation. The percentage increase in precipitation simulated by the three RCMs is generally higher than that simulated by the ensemble of GCMs. As for the changes in seasonal precipitation, RCMs exhibit a large percentage increase in seasonal precipitation in the wet season, while the ensemble of GCMs shows a large percentage increase in the dry season. Most of the hydrological simulations indicate that the total stream flow will decrease in the future due to the increase of evaporation, and the maximum percentage decrease can reach up to 22.3%. The possibility of peak flow increasing in the future is expected to higher than 99%. These results indicate that less water is likely to be available in the upper reaches of the Kaidu River Basin in the future, and that the temporal distribution of flow may become more concentrated.

Spatiotemporal changes of typical glaciers and their responses to climate change in Xinjiang,Northwest China

Glaciers are highly sensitive to climate change and are undergoing significant changes in mid-latitudes.In this study,we analyzed the spatiotemporal changes of typical glaciers and their responses to climate change in the period of 1990-2015 in 4 different mountainous sub-regions in Xinjiang Uygur Autonomous Region of Northwest China:the Bogda Peak and Karlik Mountain sub-regions in the Tianshan Mountains;the Yinsugaiti Glacier sub-region in the Karakorum Mountains;and the Youyi Peak sub-region in the Altay Mountains.The standardized snow cover index(NDSI)and correlation analysis were used to reveal the glacier area changes in the 4 sub-regions from 1990 to 2015.Glacial areas in the Bogda Peak,Karlik Mountain,Yinsugaiti Glacier,and Youyi Peak sub-regions in the period of 1990-2015 decreased by 57.7,369.1,369.1,and 170.4 km^(2),respectively.Analysis of glacier area center of gravity showed that quadrant changes of glacier areas in the 4 sub-regions moved towards the origin.Glacier area on the south aspect of the Karlik Mountain sub-region was larger than that on the north aspect,while glacier areas on the north aspect of the other 3 sub-regions were larger than those on the south aspect.Increased precipitation in the Karlik Mountain sub-region inhibited the retreat of glaciers to a certain extent.However,glacier area changes in the Bogda Peak and Youyi Peak sub-regions were not sensitive to the increased precipitation.On a seasonal time scale,glacier area changes in the Bogda Peak,Karlik Mountain,Yinsugaiti Glacier,and Youyi Peak sub-regions were mainly caused by accumulated temperature in the wet season;on an annual time scale,the correlation coefficient between glacier area and annual average temperature was-0.72 and passed the significance test at P<0.05 level in the Karlik Mountain sub-region.The findings of this study can provide a scientific basis for water resources management in the arid and semi-arid regions of Northwest China in the context of global warming.

Assessing Spatio-temporal Characteristics of Water Storage Changes in the Mountainous Areas of Central Asia Based on GRACE

The mountainous areas of Central Asia provide substantial water resources, and studying change in water storage and the impacts of precipitation and snow cover in the mountain ranges of Central Asia is of the greatest importance for understanding regional water shortages and the main factors. Data from the GRACE （Gravity Recovery and Climate Experiment） satellites, precipitation prod- ucts and snow-covered area data were used to analyze the spatio-temporal characteristics of water storage changes and the effects of precipitation and snow cover from April 2002 to December 2013. The results were computed for each mountain ranges, and the follow- ing conclusions were drawn. The water storage in the mountainous areas of Central Asia as a whole increases in summer and winter, whereas it decreases in autumn. The water storage is affected by precipitation to some extent and some areas exhibit hysteresis. The area of positive water storage changes moves from west to east over the course of the year. The water storage declined during the period 2002-2004. It then returned to a higher level in 2005-2006 and featured lower levels in 2007-009 Subsequently, the water storage increased gradually from 2010 to 2013. The Eastern Tianshan Mountains and Western Tianshan Mountain subzones examined in this study display similar tendencies, and the trends observed in the Karakorum Mountains and the Kunlun Mountains are also similar. However, the Eastern Tianshan Mountains and Western Tianshan Mountains were influenced by precipitation to a greater degree than the latter two ranges. The water storage in Qilian Mountains showed a pronounced increasing trend, and this range is the most strongly affected by precipitation. Based on an analysis of all investigated subzones, precipitation has the greatest influence on total water storage relative to the snow covered area in some areas of Central Asia. The results obtained from this study will be of value for scientists stud- ying the mechanisms that influence changes in water storage in Central Asia.

Regime dynamics of hydrochemical and toxicological parameters of the Irtysh River in Kazakhstan

Since the Irtysh River flows through the important economic, ecological and social territories of China, Kazakhstan and Russia, the water quality issues growingly draw the attention of the water authorities from these countries. Therefore, a detailed study of the hydrochemical regime and toxicological indicators in Kazakhstan was carried out for understanding the regime dynamics of water quality and its affect factors. The combined assessment of maximum permissible concentration （MPC） of chemical components and biotesting method were proposed and performed for the study area. The results clearly showed that the concentrations of single chemical component at different locations are mostly under MPC standard in a basin scale. However, the watershed surface runoff and tributary stream flow from mining industry areas had high concentration of heavy metals and had significant impact on the water quality near Ust-Kamenogorsk. Furthermore, even the stream water generally meet MPC standard, the results of biotesting method show the toxicity level of water sample is lethal for the test objects of phytoplankton and Daphnia. The survival rates of most water samples are lower than 46.7%. Hereby, this study strongly suggests using combined water assessment methods to evaluate the water quality.

一种降水降尺度模型:地形约束下的条件生成对抗网络

中亚降水数据存在缺失、地理偏差、分辨率低和采集难度大等问题。近年来,神经网络模型被广泛应用于降水降尺度研究。然而,由于山区自然环境复杂多变,普通神经网络模型的预测结果难以解释且适用性差。为此,本文以地理差异分析作为先验知识约束生成式对抗网络,构建一种新的降水降尺度模型,提高了阿姆河流域复杂环境下降水数据的空间分辨率和精度。首先,依据地形数据通过空间变形模型对输入的Climate Research Units Time Series(CRUTS)降水数据进行空间校正。然后,输入校正后的CRUTS降水数据、气温风速湿度等同化数据及遥感数据到条件生成式对抗网络,重建高分辨率降水数据。最后,考虑到山区降水的各向异性,尤其在地形复杂的上游区域,该模型基于气象站点的真值,对降水数据进行了反距离权重的地理差异分析。结果表明,基于地理差异约束生成式对抗网络的降水降尺度模型能够提升复杂环境降水数据的分辨率和精度。针对中亚阿姆河流域的实验表明,本方法可将CRUTS降水数据的分辨率由55 km提升至11 km,其R2值增加了0.34,均方根误差(RMSE)和平均绝对误差(MAE)分别减小19.4 mm和10.65 mm,偏差(Bias)也由原来的0.24降至0.08。本文为数据采集难、地形地貌复杂区域的降水数据空间分辨率的提高,提供了鲁棒性好、普适性强的方法和思路。

基于GeoSOS-FLUS模型的乌鲁木齐主城区扩张情景模拟分析

乌鲁木齐市作为新疆首府、“一带一路”中的中亚区域经济中心,其土地资源的合理利用、城市形态的健康发展则显得尤为重要。本研究首先基于乌鲁木齐主城区1990~2018年遥感影像解译出的土地利用分类对其土地利用时空演变情况加以分析,1990~2018年乌鲁木齐主城区急剧扩张,2010年以来交通网络铺设完善,主城区快速扩张,周遭耕地、林地、草地等萎缩95.12 km^(2)、6.49 km^(2)、52.37 km^(2),重心呈现出向东与向北扩张趋势,主城区农用与绿化面积萎缩,无法兼顾经济与生态效益协调可持续发展。接着,遴选自然与社会经济等影响主城区扩张的驱动因素,结合乌鲁木齐主城区扩张历史特点设计第一产业优先、第二三产业优先、生态优先情景,利用GeoSOSFLUS模型对不同情景下的主城区扩张情景进行模拟预测,研究发现第二三产业优先情景下建设用地明显增加1142.94 km^(2);生态优先情景下生态效益高的林地、草地、水域面积显著增加281.59、651.38、7.29 km^(2);第一产业优先情景下,建设用地、耕地等地类面积扩张617.14、611.71 km^(2)。上述对乌鲁木齐的城市扩张加以多情景预测推演,不仅有利于重新审视乌鲁木齐城市扩张的合理性,也可以为其未来城市合理、科学的规划与发展指明方向。