Spatio-temporal Variation of Wind Erosion in Inner Mongolia of China Between 2001 and 2010

Using Geographic Information System(GIS), based on wind speed, precipitation, topographic, soil, vegetation coverage and land use data of Inner Mongolia between 2001 and 2010, we applied the revised wind erosion equation(RWEQ) model to simulate wind erosion intensity. The results showed that an area of approximately 47.8 × 10~4 km^2 experienced wind erosion in 2010, 23.2% of this erosion could be rated as severe, and 46.0% as moderate. Both the area and the intensity of wind erosion had decreased from 2001 to 2010, the wind erosion area reduced 10.1%, and wind erosion intensity decreased by 29.4%. Precipitation, wind speed, population size and urbanization in rural areas, and gross domestic product of primary industry(GDP1) were the main factors influencing wind erosion. Overall, these factors accounted for 88.8% of the wind erosion. These results indicated that the decrease in wind erosion over the past decade related to the increase in precipitation and the decrease in the number of windy days, while modest urban development and optimization of the economic structure might partially reduced the level of ecological pressure, highlighting the importance of human activities in controlling wind erosion.

Modeling spatial and temporal change of soil erosion based on multi-temporal remotely sensed data

In order to monitor the pattern, distribution, and trend of land use/cover change （LUCC） and its impacts on soil erosion, it is highly appropriate to adopt Remote Sensing （RS） data and Geographic Information System （GIS） to analyze, assess, simulate, and predict the spatial and temporal evolution dynamics. In this paper, multi-temporal Landsat TM/ETM＋ re- motely sensed data are used to generate land cover maps by image classification, and the Cellular Automata Markov （CA_Markov） model is employed to simulate the evolution and trend of landscape pattern change. Furthermore, the Re- vised Universal Soil Loss Equation （RUSLE） is used to evaluate the situation of soil erosion in the case study mining area. The trend of soil erosion is analyzed according to total/average amount of soil erosion, and the rainfall （R）, cover man- agement （C）, and support practice （P） factors in RUSLE relevant to soil erosion are determined. The change trends of soil erosion and the relationship between land cover types and soil erosion amount are analyzed. The results demonstrate that the CA_Markov model is suitable to simulate and predict LUCC trends with good efficiency and accuracy, and RUSLE can calculate the total soil erosion effectively. In the study area, there was minimal erosion grade and this is expected to con- tinue to decline in the next few years, according to our prediction results.

Combining RUSLE model and the vegetation health index to unravel the relationship between soil erosion and droughts in southeastern Tunisia

Droughts and soil erosion are among the most prominent climatic driven hazards in drylands,leading to detrimental environmental impacts,such as degraded lands,deteriorated ecosystem services and biodiversity,and increased greenhouse gas emissions.In response to the current lack of studies combining drought conditions and soil erosion processes,in this study,we developed a comprehensive Geographic Information System(GIS)-based approach to assess soil erosion and droughts,thereby revealing the relationship between soil erosion and droughts under an arid climate.The vegetation condition index(VCI)and temperature condition index(TCI)derived respectively from the enhanced vegetation index(EVI)MOD13A2 and land surface temperature(LST)MOD11A2 products were combined to generate the vegetation health index(VHI).The VHI has been conceived as an efficient tool to monitor droughts in the Negueb watershed,southeastern Tunisia.The revised universal soil loss equation(RUSLE)model was applied to quantitatively estimate soil erosion.The relationship between soil erosion and droughts was investigated through Pearson correlation.Results exhibited that the Negueb watershed experienced recurrent mild to extreme drought during 2000–2016.The average soil erosion rate was determined to be 1.8 t/(hm2•a).The mountainous western part of the watershed was the most vulnerable not only to soil erosion but also to droughts.The slope length and steepness factor was shown to be the most significant controlling parameter driving soil erosion.The relationship between droughts and soil erosion had a positive correlation(r=0.3);however,the correlation was highly varied spatially across the watershed.Drought was linked to soil erosion in the Negueb watershed.The current study provides insight for natural disaster risk assessment,land managers,and stake-holders to apply appropriate management measures to promote sustainable development goals in fragile environments.

基于RWEQ模型的疏勒河流域防风固沙功能价值评估

疏勒河流域地处西北内陆,是“一带一路”的关键节点。近年来随着全球变化与经济社会活动强度增加,导致建设用地快速扩张、土地沙化等问题,影响区域生态与经济社会的可持续发展。疏勒河流域处于北方防沙带中心,开展其防风固沙价值评估对于构建区域生态安全格局和保障流域可持续发展具有重要生态意义。基于修正风蚀方程模型(RWEQ)对2008—2018年疏勒河流域防风固沙功能及其价值进行评估。结果表明:(1)2008—2018年疏勒河流域防风固沙总量为43.927×10^(4)~129.530×10^(4)t·km^(-2),防风固沙量呈上升趋势。(2)2008—2018年疏勒河流域防风固沙价值快速增加,其多年平均价值占比由高到低依次为减少土地损失价值(99.46%)、保持土壤肥力价值(0.47%)、保持土壤有机质价值(0.04%)、减少交通运输经济损失价值(0.03%)。(3)流域防风固沙功能与土地利用密切相关,防风固沙能力较强的区域主要分布在草地、耕地等植被覆盖率较高区域;低值区主要分布在流域土地利用类型为未利用地区域。(4)相较社会因素,自然指标因子对流域防风固沙功能价值影响更大。研究结果可为确定流域生态补偿主客体及补偿标准提供依据。

Evaluation of Inner Mongolia Wind Erosion Prevention Service based on Land Use and the RWEQ Model

Inner Mongolia is the important ecological barrier zone in northern China,which plays an important role in the prevention and control of wind in the regional ecosystem.Based on the Revised Wind Erosion Equation(RWEQ)model and the cost-recovery method,this study simulated the wind erosion prevention service(WEPS)in Inner Mongolia in 2010 and 2015,investigated the spatial pattern of material and monetary value of WEPS,and analyzed the differences among various cities and various ecosystems.The results indicated that the total WEPS of Inner Mongolia was estimated to be 73.87×10^(8) t in 2015,which was 4.61×10^(8) t less than in 2010,while the monetary value of WEPS was calculated to be 738.66×10^(8) yuan in 2015,which was 46.16×10^(8) yuan less than in 2010.Among all the leagues and cities,Xilin Gol League supported the highest WEPS,reaching 18.65×10^(8) t in 2015,while Wuhai provided the lowest.The WEPS of Hulunbeier increased the most,by 4.37×10^(8) t from 2010 to 2015.The WEPS in the grassland ecosystem was the highest among the different ecosystems,accounting for more than55%of the total WEPS in Inner Mongolia,but it was reduced by 1.05×10^(8) t during the same period.The WEPS in the forest ecosystem increased the most,reaching 0.19×10^(8) t.This study found that the implementation of projects such as returning farmland to forests and grasses and sand control effectively increased the WEPS by increasing the forest area.However,unsuitable land use increased the desertification of ecosystems which resulted in a reduction of WEPS in Inner Mongolia.

基于RWEQ模型的青海省土壤风蚀模数估算

土壤风蚀是许多国家和地区的主要环境问题之一,定量分析是风蚀研究的热点和难点。本研究基于修正风蚀模型(RWEQ),运用遥感和地理信息技术对青海省年均风蚀模数进行了估算。结果表明:青海省风蚀发生总面积为3 870万hm2,占全省面积的53.6%,年均风蚀总量约17.8亿t,平均风蚀模数为45.99t/(hm2·a)。青海省风蚀等级在大部分地区以轻度风蚀为主,整体风蚀危害不大,但在中度以上风蚀等级较为集中的柴达木盆地则风蚀危害相对严重。模型估算结果与137 Cs推算结果具有较高的拟合性(R2=0.912),表明RWEQ模型在国内区域尺度运用上具有一定可行性。

RWEQ模型中土壤结皮和可蚀性因子的改进和应用

[目的]将基于中国土壤粒径分级标准的土壤普查数据应用到RWEQ模型中,旨在解决不同土壤粒径分级标准间土壤质地资料的转换问题。[方法]利用对数正态分布模型进行土壤粒径转换,并探讨该模型在描述内蒙古自治区、吉林省、陕西省等地区土壤粒径分布中的适用情况。[结果]对数正态分布模型能够较好模拟土壤颗粒含量。土壤结皮因子和土壤可蚀性因子高值区均分布于中国北方风沙土区,其次为寒钙土等地。[结论]结皮可降低或增加土壤可蚀性,未来研究的关键在于确定不同气候条件下,引起地表结皮而将土壤风蚀可蚀性降到最低时的降雨量。

基于RWEQ模型的茫崖市防风固沙功能评估及敏感地类识别

为了较准确评估茫崖市的防风固沙功能,识别对防风固沙功能敏感的土地利用类型,通过4种方法确定修正风蚀模型(RWEQ)中的气候因子(WF)参数,计算出实际风蚀量和防风固沙量,依据指南法、自然间断法和文献—实际结合法对防风固沙功能进行了评估分级,借助ArcGIS软件将土地利用类型和防风固沙功能进行空间叠置分析以识别出敏感地类。结果表明:(1)利用风蚀气候因子(Fq)直接代替法确定的WF空间分布和阈值范围最符合实际,RWEQ模型能较准确地评估荒漠戈壁区茫崖市的防风固沙功能;(2)茫崖市2014年平均风蚀模数为57.99 kg/(m^(2)·a),属于风力侵蚀严重区域,2014年全市单位面积防风固沙量介于0~44.93 kg/m^(2),防风固沙功能整体较弱;(3)在3种评估分级方法中,文献—实际结合法更为详细地反映出2014—2018年茫崖市西南山区较强的防风固沙功能,且高等级功能的区域范围较广;(4)草地是茫崖市2014—2018年对防风固沙功能变化最敏感的土地利用类型。RWEQ模型有效评估了茫崖市的防风固沙功能,并识别出了敏感的土地利用类型。本研究为县级地区防风固沙功能评估技术的应用提供了科学参考。

基于修正风蚀模型(RWEQ)的河北省张家口市防风固沙功能空间格局研究

RWEQ(Revised Wind Erosion Equation)风蚀模型源于农田土壤风蚀量预测模型,早期适用于田块尺度,当前研究者开始尝试利用该模型测算区域尺度防风固沙能力时空格局。基于原RWEQ模型,对气象因子和地表粗糙度因子进行修正,以张家口市域为研究区,测算了2018年研究区防风固沙功能空间格局、四季动态变化,分析了相关影响因子。结果表明:1)2018年张家口市防风固沙总量为1.13亿t,单位面积防风固沙量为25.85 t/hm^(2),整体呈现坝上高原、间山盆地和燕山谷地防风固沙量低,冀西北间山盆地山区、燕山山区和太行山区防风固沙量高的空间分布格局。2)四季防风固沙量由高到低为春季、冬季、秋季、夏季,单位面积防风固沙量分别为8.32、7.65、6.92、2.96 t/hm^(2)。3)2018年张家口市单位面积防风固沙量与风力、地形起伏度和植被覆盖度均呈显著正相关,相关系数分别为0.937、0.955和0.917。修正后的模型可以用于区域尺度防风固沙功能时空格局测算,研究结果可为张家口市防风固沙功能提升和区域生态建设工程布局提供科学依据。

RWEQ模型中风因子的改进及应用

风是产生土壤风蚀的前提,实地观测的风速是时刻变化的,模型中需要不少于500个的风速值来支撑,而较高时间分辨率的风速数据难以获取,为此很多文章研究风速降尺度拟合的方法,改进修正方程中风因子估算。本文利用二参数韦伯分布函数、日均风速和日最大风速法分别拟合风速,并与实测结果进行对比研究。此外根据修正后的风速值代入RWEQ模型中得到我国北方的风因子空间分布。结果表明:二参数韦伯分布函数拟合风速所求的风蚀力与实测的风速所求的风蚀力存在误差,相对误差值从0.19到0.95,平均相对误差值达到0.52;利用二参数韦伯分布函数拟合所得风蚀力被低估;日均风速和日最大风速法也未能很好地拟合风速,但用该方法拟合风速计算结果风蚀力与实测风速计算结果风蚀力存在相关性,可利用此相关性反推出实测风蚀力;从利用2000—2010年3月份的实测风速拟合所得风因子值来看,我国内蒙古高原上各大沙地的风因子值较高,东北及青藏高原高山地带等地区的风因子值也较高。

Mathematical and statistical modeling of morphometric and planar parameters of barchans in Pashoeyeh Erg in the west of Lut Desert,Iran

Barchan dunes are among the most common accumulative phenomena made by wind erosion,which are usually formed in regions where the prevailing wind direction is almost constant throughout the year and there is not enough sand to completely cover the land surface.Barchans are among the most common windy landscapes in Pashoueyeh Erg in the west of Lut Desert,Iran.This study aims to elaborate on morphological properties of barchans in this region using mathematical and statistical models.The results of these methods are very important in investigating barchan shapes and identifying their behavior.Barchan shapes were mathematically modeled by simulating them in the coordinate system through nonlinear parabolic equations,so that two separate equations were calculated for barchan windward and slip-face parabolas.The type and intensity of relationships between barchan morphology and mathematical parameters were determined by the statistical modeling.The results indicated that the existing relationships followed the power correlation with the maximum coefficient of determination and minimum error of estimate.Combining the above two methods is a powerful basis for stimulating barchans in virtual and laboratory environments.The most important result of this study is to convert the mathematical and statistical models of barchan morphology to each other.Focal length is one of the most important parameters of barchan parabolas,suggesting different states of barchans in comparison with each other.As the barchan's focal length decreases,its opening becomes narrower,and the divergence of the barchan's horns reduces.Barchans with longer focal length have greater width,dimensions,and volume.In general,identifying and estimating the morphometric and planar parameters of barchans is effective in how they move,how much they move,and how they behave in the environment.These cases play an important role in the management of desert areas.

Sand-fixing Function under the Change of Vegetation Coverage in a Wind Erosion Area in Northern China

Using meteorological and remote sensing data and changes in vegetation cover during the wind erosion season in northern China, a revised wind erosion equation was applied to evaluate spatiotemporal variation in soil erosion and conservation since the 1990s, and to reveal the effects of the change of vegetation coverage on the wind erosion control service. The results showed that average soil erosion in northern China between 1990 and 2010 was 16.01 bil ion tons and was decreasing. The most seriously eroded areas were mainly distributed in large desert areas or low cover grasslands. Most wind erosion occurred in spring, accounting for 45.93% of total wind erosion. The average amount of sand ifxation service function for northern China between 1990 and 2010 was 20.31 billion tons. Given the influence of wind erosion forces, the service function for sand fixation cannot effectively highlight the role of sand ifxation from the ecosystem itself. The retention rate of service function for sand ifxation reveals the role of the ecosystem itself. The distribution characteristics of the soil retention rate are similar to vegetation cover, which shows a gradual decrease from southeast to northwest in the study area. Improved spring vegetation cover was observed mainly on the Loess Plateau, Qinghai-Tibet Plateau, in northern Hebei, eastern Inner Mongolia and northeast China after the implementation of ecosystem projects. The soil retention rate in most areas showed a signiifcant positive relationship with grassland vegetation in spring （r＆gt;0.7, p＆lt;0.01）. The increments of ecosystem service function for various ecological systems are different. Increments for the grassland ecosystem, forest ecosystem, farmland ecosystem and desert ecosystem are 2.02%, 1.15%, 0.99% and 0.86%, respectively.

甘肃省武威市风力侵蚀分区治理规划及措施

[目的]分析甘肃省武威市风力侵蚀空间动态变化特征,确定风力侵蚀可治理区划及其防治对策,为该市风蚀水土保持工作和生态环境建设提供科学参考。[方法]基于多源地理信息数据,应用遥感、地理信息系统(ArcGIS)等技术手段,使用修正土壤风蚀方程(RWEQ)计算武威市2000—2020年5期风蚀模数,获得区域风蚀的面积分布和变化特征。结合重点建设工程分布等空间要素叠加分析方法,提出该市风力侵蚀可治理区域划分原则,并将该原则应用于划分武威市风力侵蚀可治理区。[结果]修正土壤风蚀方程(RWEQ)能较好地估算武威市多年风力侵蚀模数,其多年风力侵蚀模数为5788.98〔t/(km^(2)·a)〕,多年平均土壤风蚀总量1.92×10^(8)t;研究区风力侵蚀在时间上呈现总体下降,偶有上升趋势,且风力侵蚀强度等级明显减弱;在空间上具有明显的空间异质性,主要分布在民勤县、凉州区、古浪县;依据多要素叠加风蚀分区治理方案,武威市可治理风力侵蚀面积共2872.66km^(2),其中民勤县1468.48km^(2),凉州区708.75km^(2),古浪县695.43km^(2)。[结论]风力侵蚀分区治理是武威市风蚀水土保持的重点工作,根据风蚀分区治理划分结果,针对不同行政区划,民勤县北部坡度较低的平坦戈壁沙漠地区是其重点关注区域,治理措施应以风沙防治和植被恢复为主,并需要注意控制人为工程建设扰动的影响,明确区域管理范围;凉州区应注意采取工程措施和生物措施结合的方式进行治理;古浪县应以封育措施和对天然植被进行保护为主。同时,在戈壁沙漠地区需特别注意大型光伏电站建设等施工扰动的风沙防治和生态恢复。

内蒙古自治区重点生态功能区生态系统类型转换对土壤风蚀的影响

[目的]内蒙古自治区重点生态功能区是中国北方生态安全重要屏障。揭示该区生态系统类型转换及对土壤风蚀的影响,为促进该区生态环境安全与绿色发展提供科学参考。[方法]基于土地利用、气象和基础地理信息等数据,采用修正的土壤风蚀方程模型,揭示内蒙古地区重点生态功能区生态系统类型与土壤风蚀的时空变化特征,并剖析生态系统类型转换及其对土壤风蚀的影响。[结果](1)2000—2022年内蒙古地区重点生态功能区内生态系统间转换强烈,生态系统类型转换总面积6019.59 km^(2),以草地与荒漠以及耕地与林草的相互转化为主,2015年之后生态系统趋向稳定,各类生态系统动态变化强度降低;(2)内蒙古地区重点生态功能区平均土壤风蚀模数为56.39 t/hm^(2),按土壤风蚀量由大到小为荒漠、草地、农田和森林生态系统,土壤风蚀程度以微度和轻度侵蚀为主,主要分布在大小兴安岭森林生态功能区和科尔沁草原生态功能区等区域;(3)内蒙古地区重点生态功能区各类生态系统类型之间的转换造成土壤风蚀量净减少了1.08×10^(8)t,生态退耕、耕地开垦、草地质量提升、荒漠化防治和建设用地扩展造成土壤风蚀模数分别减少了0.11,0.23,0.66,0.84,0.68 t/hm^(2)。[结论]应加强巩固内蒙古重点生态功能区的生态治理成效,避免复垦与新开荒事件发生,促进内蒙古地区荒漠化综合防治及高质量发展。

新疆生态区的生态系统服务的时空变化特征分析

基于土地覆被与分类数据、气象数据、流域数据、土壤数据、数字高程模型(Digital Elevation Model,DEM)、归一化植被指数(Normalized Difference Vegetation Index,NDVI)等数据,利用生态系统服务评估与权衡模型(Integrated Valuable of Ecosystem Services and Tradeoffs Model,InVEST)和改进风蚀方程(Revised Wind Erosion Equation,RWEQ),评估了1992~2018年新疆各生态区的生态系统服务的时空变化及各生态区的服务簇变化。结果表明:1)1992~2018年新疆生境支持服务和碳储存与封存服务能力显著提高,其中在阿尔泰山—准噶尔西部山地森林草原生态区、天山山地森林与草原生态区和帕米尔—昆仑山—阿尔金山高寒草原生态区最为显著。2)土壤保持服务和防风固沙服务以2007年为界呈现分段特征。1992~2007年土壤保持服务和防风固沙服务能力下降,而2007~2018年两种服务能力都呈上升趋势,总体呈现改善趋势。3)以生态区为单位,每个生态区的核心生态系统服务不同。1992~2018年各服务簇整体服务能力提高。区域生态系统服务评估是厘清生态系统复杂性的关键,本研究可为推进新疆乃至干旱区的生态规划、生态修复与保护,提高生态系统服务能力的重要参考。

无定河流域防风固沙服务流动模拟

无定河流域包括毛乌素沙漠部分区域,土壤风蚀显著,研究防风固沙服务有利于保持土壤、保护生态环境与维持良好的人地关系。利用RWEQ(Revised Wind Erosion Equation)模型与HYSPLIT(Hybrid Single-Particle Langrangian Integrated Trajectory Model)模型模拟无定河流域2000年、2005年、2010年、2015年以及2018年的土壤风蚀量以及防风固沙服务流的时空变化,并分析受益人口与real GDP。结果表明:(1)2000年至2018年无定河流域风蚀总量与防风固沙量呈“降低-增加-降低”的波动变化整体下降的趋势,在空间分布上,无定河流域西部及西北部沙地土壤风蚀较为剧烈,东部及东南部的旱地土壤风蚀较为缓和;(2)2000年至2018年防风固沙服务流动路径模拟总数分别为494条、504条、537条、482条与437条,整体上呈降低的趋势,受益区主要分布于我国的中部及东部地区以及俄罗斯、韩国等周边国家;(3)2000年至2018年防风固沙服务全国受益人口与受益real GDP均占据总数一定比例;(4)无定河流域防风固沙服务物质流以陕西北部、山西西部地区为中心呈圈层状递减,影响范围扩散到了东亚和东南亚等国家和地区。结果模拟了无定河流域土壤风蚀以及防风固沙服务流,为服务供给区和受益区之间的生态补偿提供科学依据,对植被恢复与防风固沙具有一定的参考作用,可为其他流域的防风固沙服务流动模拟和整个三北地区的防风固沙生态工程的规划、建设、评估提供重要的科学参考。

Wind Erosion Climate Change in Northern China During 1981-2016

Wind erosion is largely controlled by climate conditions.In this study,we examined the influences of changes in wind speed,soil wetness,snow cover,and vegetation cover related to climate change on wind erosion in northern China during 1981–2016.We used the wind erosion force,defined as wind factor in the Revised Wind Erosion Equation Model,to describe the effect of wind speed on wind erosion.The results show that wind erosion force presented a long-term decreasing trend in the southern Northwest,northern Northwest,and eastern northern China during 1981–2016.In the Gobi Desert,the wind erosion force presented for 1981–1992 a decreasing trend,for 1992–2012 an increasing trend,and thereafter a weakly decreasing trend.In comparison to wind speed,soil wetness and snow cover had weaker influences on wind erosion in northern China,while vegetation cover played a significant role in the decrease of wind erosion in the eastern northern China during 1982–2015.

内蒙古土地利用变化对生态系统防风固沙功能的影响

土壤风蚀是内蒙古的严重环境问题之一。在对内蒙古2000年到2010年的土地利用变化特征进行分析的基础上,分析了内蒙古土地利用变化的主要特征,以RWEQ模型估算了内蒙古2000年和2010年的固沙物质量,采用空间统计分析评估了固沙功能对土地利用变化的响应,结果表明:(1)2000—2010年土地利用变化以城镇高速发展、草地和湿地面积锐减、林地灌丛有所恢复以及荒漠环境改善为主要特征。(2)2000—2010的十年间内蒙古固沙物质总量增长了17.75%,草地总面积虽有所降低,但是部分区域草地覆盖度的上升增强了草地固沙能力,而林地的固沙物质量则由于农田、草地改为林地的短期内地表保护力的下降而有所降低。(3)十年间农田退耕还草、荒漠环境的改善、草地质量提高等土地利用变化方式有益于生态环境质量的提高,使生态防风固沙功能得以增强,造成固沙物质量提高了约0.25亿t。(4)农田开垦、城镇发展、荒漠化发展、湿地萎缩以及草地的退化等土地利用变化会使生态环境质量降低,生态系统防风固沙功能下降,累计造成的固沙物质量的减少总量约为0.19亿t。从十年间综合来看,内蒙古的土地利用变化对区域固沙功能有一定的增强作用,但是尚存在城镇发展过快、草地湿地转化压力过大、草地退化、荒漠化对固沙功能的弱化问题,需要在今后的土地利用规划和管理工作中予以改进以进一步增强区域固沙功能,构建北方地区生态安全屏障。

三峡库区小流域修正通用土壤流失方程适用性分析

土壤侵蚀量的定量研究可为国家生态环境建设和水土保持宏观决策的制定提供重要的依据。修正通用土壤流失方程(revised universal soil loss equation,RUSLE)是开展土壤侵蚀定量评价的主要手段。该文在地理信息系统(geographic information system,GIS)的支持下,依据中国土壤流失方程各因子的算法确定RUSLE模型各因子值,估算了三峡库区黄冲子小流域不同时期的土壤侵蚀量,并与基于泥沙平衡原理计算的土壤侵蚀量比较后分析RUSLE模型在库区小流域的适用性。结果表明,基于RUSLE模型估算的小流域1963-2000年(农地小流域)和2001-2014年(林地小流域)的年均土壤侵蚀模数分别为2246.09和868.3 t/(km2·a),其结果与采用137Cs和210Pb技术的塘库沉积物定年结果基本吻合,表明210Pb定年结果可靠。依据泥沙平衡原理计算的小流域1963-2000年和2001-2014年的年均土壤侵蚀模数分别为942.48和811.47t/(km2·a)。RUSLE模型估算小流域1963-2000年和2001-2014年的土壤侵蚀模数相对误差分别为138.32%和7.00%。因此RUSLE模型适用于库区林地小流域,而不适用于库区农地小流域;但是基于地形因子(LS因子)修正的RUSLE模型估算结果相对误差减少至8.14%,其适用于库区农地小流域。

基于多源数据的京津风沙源区防风固沙功能变化

防风固沙功能是评估区域生态安全程度的重要指标,研究其时空变化和内部差异可为改善生态环境和促进生态系统可持续发展提供重要参考。基于京津风沙源区多源遥感数据,利用修正风蚀方程(RWEQ)和GIS空间统计技术,评估分析了2000—2017年京津风沙源区防风固沙功能时空变化及其区域内部差异。结果表明:(1)区域防风固沙功能明显提升,年均防风固沙量为40.06亿t,防风固沙能力为56.38 t/hm^(2),且均随年份变化波动增加,年均增速分别为0.41亿t,0.58 t/hm^(2)。其中,二期新增区域防风固沙能力高于一期工程区域。(2)在亚区尺度上,5个亚区整体防风固沙能力均呈增加趋势,其中鄂尔多斯高原沙化土地治理区增加最为明显,为1611.35万t/a。其中,鄂尔多斯高原沙化土地治理区和坝上草原及华北北部丘陵山地水源涵养治理区是防风固沙功能的主要供给区,占比达57.96%。(3)在像元尺度上,区域自西向东大致呈现出高—低—高的变化趋势,评估期内有54.11%的地区防风固沙能力呈现增加趋势,变动值介于0.10~12.22 t/(hm^(2)·a)。此外,46.83%的地区防风固沙能力高于45.00 t/hm^(2),防风固沙功能较强。