Machine learning-based identification for the main influencing factors of alluvial fan development in the Lhasa River Basin,Qinghai-Tibet Plateau

Journal of Geographical Sciences - Alluvial fans are an important land resource in the Qinghai-Tibet Plateau with the expansion of human activities. However, the factors of alluvial fan development...     

Alpine wetlands in the Lhasa River Basin, China

The Lhasa River Basin is one of the typical distribution regions of alpine wetlands on the Tibetan Plateau. It is very important to get a better understanding of the background and characteristics of alpine wetland for monitoring, protection and utilization. Wetland construction and distribution in the basin were analyzed based on multi-source data including field investigation data, CBERS remote sensing data and other thematic data provided by 3S technology. The results are (1) the total area of wetlands is 209,322.26 hm2, accounting for 6.37% of the total land area of the basin. The wetlands are mainly dominated by natural wetland, with artificial wetland occupying only 1.09% of the wetland area; marsh wetland is the principal part of natural wetland, dominated by Kobresia littledalei swampy meadow which is distributed in the river source area and upstream of Chali, Damshung and Medro Gongkar counties. The ratio and type of wetlands in different counties differ significantly, which are widely distributed in Chali and Damshung counties (accounting for 62% of the total wetland area). (2) The concentrated vertical distribution of wetlands is at an elevation of 3600–5100 m. The wetlands are widely distributed throughout the Yarlung Zangbo River Valley from river source to river mouth into the Yarlung Zangbo River. Marsh wetland is dominant in the source area and upstream of the river, with the mosaic distribution of lakes, Kobresia littledalei and Carex moorcroftii swampy meadow, shrubby swamp and river; as for the middle-down streams, the primary types are river wetland and flooded wetland. The distribution is in a mosaic pattern of river, Kobresia humilis and Carex moorcroftii swampy meadow, Phragmites australis and subordinate grass marsh, flooded wetland and artificial wetland.     

拉萨河流域高寒湿地分布

The Lhasa River Basin is one of the typical distribution regions of alpine wetlands on the Tibetan Plateau.It is very important to get a better understanding of the background and characteristics of alpine wetland for monitoring,protection and utilization.Wetland construction and distribution in the basin were analyzed based on multi-source data including field investigation data,CBERS remote sensing data and other thematic data provided by 3S technology.The results are(1) the total area of wetlands is 209,...     

Impacts of land use changes on groundwater resources in the Heihe River Basin

Land use and land cover changes have a great impact on the regional hydrological process. Based on three periods of remote sensing data from the 1960s and the long-term observed data of groundwater from the 1980s, the impacts of land use changes on the groundwater system in the middle reach of Heihe River Basin in recent three decades are analyzed by the perspective of groundwater recharge and discharge system. The results indicate that with the different intensities of land use changes, the impacts on the groundwater recharge were 2.602×108 m3/a in the former 15 years (1969-1985) and 0.218×108 m3/a in the latter 15 years (1986-2000), and the impacts on the groundwater discharge were 2.035×108 m3/a and 4.91×108 m3/a respectively. When the groundwater exploitation was in a reasonable range less than 3.0×108 m3/a, the land use changes could control the changes of regional groundwater resources. Influenced by the land use changes and the large-scale exploitation in the recent decade, the groundwater resources present apparently regional differences in Zhangye region. Realizing the impact of land use changes on groundwater system and the characteristics of spatial-temporal variations of regional groundwater resources would be very important for reasonably utilizing and managing water and soil resources.     

黑河流域土地利用变化对地下水资源的影响

Land use and land cover changes have a great impact on the regional hydrological process. Based on three periods of remote sensing data from the 1960s and the long-term observed data of groundwater from the 1980s, the impacts of land use changes on the groundwater system in the middle reach of Heihe River Basin in recent three decades are analyzed by the perspective of groundwater recharge and discharge system. The results indicate that with the different intensities of land use changes, the impacts on the groundwater recharge were 2.602 × 10^8 m^3/a in the former 15 years （1969-1985） and 0.218 × 10^8 m^3/a in the latter 15 years （1986-2000）, and the impacts on the groundwater discharge were 2.035 × 10^8 m^3/a and 4.91 × 10^8 m^3/a respectively. When the groundwater exploitation was in a reasonable range less than 3.0 × 10^8 m^3/a, the land use changes could control the changes of regional groundwater resources. Influenced by the land use changes and the large-scale exploitation in the recent decade, the groundwater resources present apparently regional differences in Zhangye region. Realizing the impact of land use changes on groundwater system and the characteristics of spatial-temporal variations of regional groundwater resources would be very important for reasonably utilizing and managing water and soil resources.     

20世纪90年代无定河流域土地利用的时空变化

本文基于ArcGIS平台,以LandsatTM影像解译得到的三期土地利用数据为基础,结合统计分析工作,对无定河流域20世纪90年代土地利用数量、类型及其变化进行了分析。分析得出,前后2个5年间,无定河流域耕地、林地和未利用土地都是先减少而后稍有增加,草地则是先增加后稍有减少。在10年尺度上土地利用总的动态特征是,耕地与未利用土地面积减少,林地、草地面积增加。前5年无定河流域综合土地利用动态度为0.85%,未利用土地和草地的年变化率较大,耕地与水域年变化率较低。后5年无定河流域综合土地利用动态度为0.3%,林地与未利用土地年变化率较大,耕地与水域变化率较小。最后引入单一土地利用类型相对变化率反映出无定河流域土地利用变化存在明显的区域差异。     

太行山淇河流域土地利用变化对生境的影响

山地作为陆地表面的特殊地域单元,地形起伏较大,生态系统较为脆弱,对全球变化信号有放大作用。因此,研究山地土地利用变化对生境质量的影响,对于权衡区域生态保护与发展及土地资源的可持续利用具有重要意义。本文基于InVEST模型,结合土地利用数据,并从地形起伏度视角,对太行山淇河流域2000-2015年生境质量进行研究。结果表明：①2000-2015年期间,淇河流域土地利用变化表现为耕地、林地面积逐渐减少,草地、建设用地面积逐渐增加。②流域整体生境质量较好,平均生境质量指数均超过0.7,且2015年有明显提升。③淇河流域的生境质量变化受地类变化影响较大。耕地、草地、建设用地由于受到过人为干扰的影响,其生境出现不同程度的退化;采伐、毁林开荒等行为导致林地的生境也开始缓慢退化,但由于林地的植被覆盖度较高,抗干扰能力较强,加上逐渐开始对其进行恢复,生境质量水平依然较高。④该流域生境质量在地形起伏度上的分布特征表现为平坦区和微起伏区以一般等级生境质量为主,小起伏区和中起伏区则以高度重要和极重要等级生境质量为主。     

塔里木河中上游土地利用变化的径流响应

为了定量分析塔里木河中上游土地利用变化对径流的影响程度,基于塔里木河流域1980-2015年土地利用数据及相关水文系列资料,利用MIKE SHE分布式水文模型客观模拟评价了流域中上游土地利用变化下的水文响应过程。结果表明：MIKE SHE模型可以较好的模拟塔里木河流域中上游的日流量过程,在研究区具有良好的适用性;1980-2015年间流域土地利用变化导致流域地表日径流量减少了4.2 m³·s^-1。通过仿真模拟分析草地、林地、耕地三种土地利用情景,得到日均流量分别为147.56 m³·s^-1、141.80 m³·s^-1,144.72 m³·s^-1由此可见,该流域径流对不同土地利用类型的响应差异较大,产流量的总体趋势为草地>耕地>林地。研究成果对于流域土地利用格局的合理规划及极端水文事件的控制具有重要意义。     

拉萨地区土地利用变化

根据1990年、1995年和2000年3期西藏拉萨地区土地利用现状调查数据,利用GIS空间分析方法,系统地分析了1990年至2000年间拉萨地区的土地利用时空变化特征。得出: ① 10年来拉萨地区的土地利用类型转变主要发生在人类活动比较集中的城镇附近和河谷地区,很多地段的天然植被由人工植被所取代,植被覆盖度和生物产量明显提高,有效地改善了这些区域的土地覆盖状况,这些变化是这一期间实施的农业综合开发中旨在改变区域生态环境的人工植树造林和改良草场等人为有目的地改变土地利用类型的直接结果;② 10年内面积增幅最大的是林地,增加了2.56%;③ 土地利用类型变化最广泛的是牧草地,由牧草地变成耕地、园地、林地、居民点及水域的,其中牧草地变成林地的面积最大,占变化面积的94.09%;④ 耕地变成林地的面积占耕地移出总量的54.86%,变成居民点的占移出面积的38.25%;⑤ 水域变成林地的面积占变化面积的93.13%。     

Land use dynamics in Lhasa area, Tibetan Plateau

Land use change is the result of the interplay between socioeconomic, institutional and environmental factors, and has important impacts on the functioning of socioeconomic and environmental systems with important tradeoffs for sustainability, food security, biodiversity and the vulnerability of people and ecosystems to global change impacts. Based on the results of the First Land Use Survey in Tibet Autonomous Region carried out in the late 1980s, land use map of Lhasa area in 1990 was compiled for the main agricultural area in Lhasa valley using aerial photos obtained in April, May and October 1991 and Landsat imagery in the late 1980s and 1991 as remotely sensed data sources. Using these remotely sensed data, the land use status of Lhasa area in 1991, 1992, 1993, 1995, 1999 and 2000 were mapped through updating annual changes of cultivated land, artificial forest, grass planting, grassland restoration, and residential area and so on. Land use map for Lhasa area in 2007 was made using ALOS AVNIR-2 composite images acquired on October 24 and December 26, 2007 through updating changes of main land use types. According to land use status of Lhasa area in 1990, 1995, 2000 and 2007, the spatial and temporal land use dynamics in Lhasa area from 1990 to 2007 are further analyzed using GIS spatial models in this paper.     

拉萨地区土地利用动态分析

Land use change is the result of the interplay between socioeconomic, institutional and environmental factors, and has important impacts on the functioning of socioeconomic and environmental systems with important tradeoffs for sustainability, food security, biodiversity and the vulnerability of people and ecosystems to global change impacts. Based on the results of the First Land Use Survey in Tibet Autonomous Region carried out in the late 1980s, land use map of Lhasa area in 1990 was compiled for the main agricultural area in Lhasa valley using aerial photos obtained in April, May and October 1991 and Landsat imagery in the late 1980s and 1991 as remotely sensed data sources. Using these remotely sensed data, the land use status of Lhasa area in 1991, 1992, 1993, 1995, 1999 and 2000 were mapped through updating annual changes of cultivated land, artificial forest, grass planting, grassland restoration, and residential area and so on. Land use map for Lhasa area in 2007 was made using ALOS AVNIR-2 composite images acquired on October 24 and December 26, 2007 through updating changes of main land use types. According to land use status of Lhasa area in 1990, 1995, 2000 and 2007, the spatial and temporal land use dynamics in Lhasa area from 1990 to 2007 are further analyzed using GIS spatial models in this paper.     

The trend on runoff variations in the Lhasa River Basin

Taking the Lhasa River Basin above Lhasa hydrological station in Tibetan Plateau as a study area, the characteristics of the annual and monthly mean runoff during 1956?2003 were analyzed, based on the hydro-data of the two hydrological stations (Lhasa and Tanggya) and the meteorological data of the three meteorological stations (Damxung, Lhasa and Tanggya). The trends and the change points of runoff and climate from 1956 to 2003 were detected using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. The correlations between runoff and climate change were analyzed using multiple linear regression. The major results could be summarized as follows: (1) The annual mean runoff during the last 50 years is characterized by a great fluctuation and a positive trend with two change points (around 1970 and the early 1980s), after which the runoff tended to in-crease and was increasing intensively in the last 20 years. Besides, the monthly mean runoff with a positive trend is centralized in winter half-year (November to April) and some other months (May, July and September). (2) The trends of the climate change in the study area are generally consistent with the trend of the runoff, but the leading climate factors which aroused the runoff variation are distinct. Precipitation is the dominant factor influencing the annual and monthly mean runoff in summer half year, while temperature is the primary factor in winter season.     

1956-2003年拉萨河流域径流变化趋势

Taking the Lhasa River Basin above Lhasa hydrological station in Tibetan Plateau as a study area, the characteristics of the annual and monthly mean runoff during 1956-2003 were analyzed, based on the hydro-data of the two hydrological stations （Lhasa and Tanggya） and the meteorological data of the three meteorological stations （Damxung, Lhasa and Tanggya）. The trends and the change points of runoff and climate from 1956 to 2003 were detected using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. The correlations between runoff and climate change were analyzed using multiple linear regression. The major results could be summarized as follows： （1） The annual mean runoff during the last 50 years is characterized by a great fluctuation and a positive trend with two change points （around 1970 and the early 1980s）, after which the runoff tended to increase and was increasing intensively in the last 20 years. Besides, the monthly mean runoff with a positive trend is centralized in winter half-year （November to April） and some other months （May, July and September）. （2） The trends of the climate change in the study area are generally consistent with the trend of the runoff, but the leading climate factors which aroused the runoff variation are distinct. Precipitation is the dominant factor influencing the annual and monthly mean runoff in summer half year, while temperature is the primary factor in winter season.     

塔里木河流域土地利用监测适宜尺度选择方法

Optimal scale is one of the important issues in ecology and geography. Based on land-use data of the Tarim River Basin in Xinjiang of China in the 1950s, regarding the area of land use types as the parameter in scale selecting, the histograms of the patches in area are charted. Then, by reinforcing the normalized scale variances (NSV) with 3 landscape indices, the scale characteristics of land use in the Tarim River Basin can be summarized. (1) NSV in the Tarim River up to a maximum at scale of 1:50,000 which is considered appropriate for the Tarim River. (2) Diversity indices of saline land are consistent with NSV’s. Diversity indices and NSV of sandy land showed that the appropriate scale is in the same scale domain. There is a significant difference between diversity indices and NSV of forestland and shrubland. (3) Fractal dimension of sandy land and saline land showed a hierarchical structure at a scale of 1:10,000. Fractal dimension of forestland and shrubland are distributed under the same hierarchical structure in the region. Foundation: National Natural Science Foundation of China, No.40571030; No.40730633 Author: Zhao Jin (1980–), Ph.D, specialized in study of scale effect.     

A method for choice of optimum scale on land use monitoring in Tarim River Basin

Optimal scale is one of the important issues in ecology and geography. Based on land-use data of the Tarim River Basin in Xinjiang of China in the 1950s, regarding the area of land use types as the parameter in scale selecting, the histograms of the patches in area are charted. Then, by reinforcing the normalized scale variances (NSV) with 3 landscape indices, the scale characteristics of land use in the Tarim River Basin can be summarized. (1) NSV in the Tarim River up to a maximum at scale of 1:50,000 which is considered appropriate for the Tarim River. (2) Diversity indices of saline land are consistent with NSV’s. Diversity indices and NSV of sandy land showed that the appropriate scale is in the same scale domain. There is a significant difference between diversity indices and NSV of forestland and shrubland. (3) Fractal dimension of sandy land and saline land showed a hierarchical structure at a scale of 1:10,000. Fractal dimension of forestland and shrubland are distributed under the same hierarchical structure in the region.     

陕西大理河流域土地利用/覆被变化的水文效应

近年来,土地利用/覆被变化的水文效应研究已成为国际的前沿和重点。在大理河流域,LUCC(包括水土保持措施)对水循环和水量平衡产生了深远影响,该流域LUCC水文效应的研究势在必行。根据研究区1990年代三期土地利用数据分析了LUCC的时空变化特征,采用特征变量时间序列法及降水-径流模型对LUCC水文效应进行了研究。结果表明:流域土地利用类型以耕地和草地为主,近10年来,耕地和草地面积有所减少,而林地和建设用地面积持续增加;流域年径流和月径流演化过程均表现出明显的下降趋势;LUCC及水土保持具有减少流域年径流、汛期流量以及增加枯季流量的作用,相对于降水因素,人类活动对流域水文的作用占主导地位;在1990~2000年期间,主要由LUCC引起的年均径流减少量达2616.6×10⁴ m³,占该期间实测减水总量的62.19%。     

基于土地利用变化的甘肃省黄河流域生态系统服务价值研究北大核心CSCD

为探究1995—2020年甘肃省黄河流域基于土地利用的生态系统服务价值时空变化,选取甘肃省黄河流域1995、2000、2005、2010、2015、2020年6期土地利用数据,分别利用土地利用动态度、土地利用程度指数和土地利用转移矩阵分析了研究区土地利用时空变化特征;通过对单个生态系统服务价值当量的经济价值进行修正,计算分析了研究区6个不同时期的生态系统服务价值,进而探讨了研究区土地利用程度对生态系统服务价值的影响。结果表明:(1)1995—2020年,研究区耕地和未利用地面积总体减小,林地、草地、水域和建设用地面积总体增加,变化最大的是建设用地;(2)1995—2020年,研究区草地的土地利用程度最高,其他地类转为草地的面积最大;(3)1995—2020年,研究区生态系统服务价值总体呈增加趋势,共增加5.104亿元;(4)从2020年土地利用类型来看,草地的生态系统服务价值最大,达255.016亿元;从2020年生态系统服务类型来看,保持土壤生态服务价值最大,达87.94亿元;从生态敏感性指数来看,研究区生态系统服务价值敏感性指数均<1,研究结果可信;从生态系统服务加之分级来看,中级比重较大,面积占比为82.07%;(5)研究区土地利用程度与生态系统服务价值呈显著负相关,相关系数为0.912。     

黄河中游多沙粗沙区（渭河段）土地利用对植被盖度的影响

针对黄河中游多沙粗沙区植被变化及其影响因素研究薄弱环节,利用MSS、TM和环境星CCD等多源遥感数据,运用相邻图幅递进回归分析消除时相差异后反演植被盖度,人机交互式解译土地利用,研究黄河中游多沙粗沙区（渭河段） 1978-2010 年间3 个时期土地利用对植被盖度的影响。结果表明：（1） 研究区内植被盖度已显著恢复,植被变化有较强的波动性和异质性;（2） 土地利用已发生明显变化,土地利用变化有较强的时空分异特征;（3） 土地利用转型和渐变均有利于促进植被盖度恢复,但土地利用转型对植被恢复的贡献更突出;（4） 土地利用对植被盖度的影响有一定的复杂性和差异性,区域植被持续恢复迫切需要有针对性的土地利用转型与生态系统优化策略。     

长江流域土地利用时空变化特征及其径流效应

土地利用变化的径流效应是水循环研究中的重点内容之一。长江流域是中国最大的流域,土地利用变化及其径流效应分析是研究该流域径流演变、水旱灾害的基础。本文利用1980、1990、1995、2000、2005年五期土地利用数据,采用土地利用转移矩阵计算土地利用动态度、交换变量等指标,评价了长江流域土地利用的时空变化特征,识别关键变化区域及其变化原因。在此基础上,利用SCS模型的降水—径流方程,分析了土地利用变化的径流效应。研究结果表明：1980-2005年时期,长江流域土地转移活跃程度在第一(1980-1990年)和第四(2001-2005年)时期内明显高于1991-1995年和1996-2000年,中上游四川及其北部地区的活跃程度最大。1980-2005年期间水田、旱地、林地和草地面积变化幅度都在8%以内。但受不同时期环境保护和经济发展因素影响,耕地(水田和旱地)和林地、草地呈现相反的变化,而水域、未利用地和城镇用地相对变化较大;其中快速的城镇化导致城镇用地增幅最高,可达196.58%。土地利用变化直接导致流域的平均径流系数变大,变幅从-0.67%到0.80%,平均增幅0.05%,变化最显著的地区在城市化水平较高的长三角一带。径流系数的增加导致洪水发生的可能性增大。     

基于PLUS和InVEST模型的渭河流域土地利用与生境质量时空变化及预测

生境质量是关系人类福祉和实现可持续发展的重要基础,对区域生态保护和土地资源可持续利用具有重大意义。以渭河流域为研究对象,基于2000、2010年和2020年的土地利用数据,应用斑块生成土地利用变化模拟（Patch-generating land use simulation,PLUS）模型、生态系统服务和权衡的综合评估（Integrated valuation of ecosystem services and trade-offs,InVEST）模型预测并评价了土地利用与生境质量时空变化特征。结果表明：（1） 2000—2020年渭河流域建设用地和草地面积逐年增加,林地面积略微增长,耕地面积持续减少;2020—2050年土地利用变化趋势同2000—2020年基本一致但剧烈程度显著下降,建设用地扩张趋势减缓,耕地减少幅度下降,草地面积占比超过耕地跃居流域第一。（2） 2000—2020年流域内生境质量两极分化趋势明显,低生境质量和高生境质量区域面积有所增加,中等生境质量的面积减少,整体生境质量水平呈上升趋势;2020—2050年生境质量水平继续保持逐年上升趋势但增幅放缓,生境质量变化强度下降,低生境质量区域面积逐渐减少,中等生境质量面积保持稳定,高生境质量面积有所增长。研究结果可为渭河流域土地资源可持续利用和高质量发展提供相应科学依据和决策参考。