Erosion environment in the sediment-rich area on the Loess Plateau

Based on the investigation and analysis of characteristics of precipitation, natural environment, socio-economic factors and soil erosion, this paper indicates that the precipitation is the main driving force for the soil erosion in the sediment-rich area, its variability determines the characteristics of soil and water loss; the natural conditions such as the drainage systems, geological and topographic features, the composition of soil and land surface materials, vegetation and climate determine the seriousness of soil and water loss; irrational socio-economic activities of human beings usually accelerated soil and water loss; meanwhile, the low preservation rate and inferiority of soil and water conservation measures made it impossible to make rapid progress on soil and water loss control. Furthermore, the characteristics of erosion environment endowed this area with more sediment that is the main reason for the flooding disasters by the Yellow River. Therefore, more emphasis should be placed on the enhancement of soil and water conservation. The soil loss prediction models will provide scientific basis for the planning of soil and water conservation, the designing of soil and water conservation measures and the valuation of effects of soil and water loss control. According to the analysis of the previous studies on soil loss prediction, and the water-sediment variation features, it is thought that study on soil loss prediction under various rainfall conditions and soil-water conservation measures should be carried out.

Characteristics of root pullout resistance of Caragana korshinskii Kom.in the loess area of northeastern Qinghai-Tibet Plateau,China

Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in order to improve our knowledge of pullout resistance characteristics of taproot systems of shrub species,we selected the shrub species Caragana korshinskii Kom.in different growth periods as the research plant and conducted in situ root pullout test.The relationships among the maximum pullout resistance,peak root displacement,shrub growth period,and aboveground growth indices(plant height and plant crown breadth)were analyzed,as well as the mechanical process of uprooting.Pullout resistance of 4-15 year-old C.korshinskii ranged from 2.49(±0.25)to 14.71(±4.96)kN,and the peak displacement ranged from 11.77(±8.61)to 26.50(±16.09)cm.The maximum pullout resistance and the peak displacement of roots increased as a power function(R^(2)=0.9038)and a linear function(R^(2)=0.8242)with increasing age,respectively.The maximum pullout resistance and the peak displacement increased with increasing plant height;however,this relationship was not significant.The maximum pullout resistance increased exponentially(R^(2)=0.5522)as the crown breadth increased.There was no significant relationship between the peak displacement and crown breadth.The pullout resistance and displacement curve were divided into three stages:the initial nonlinear growth,linear growth,and nonlinear stages.Two modes of failure of a single root occurred when the roots were subjected to vertical loading forces:the synchronous breakage mode and the periderm preferential breakage mode.These findings provide a foundation for further investigation of the soil reinforcement and slope protection mechanisms of this shrub species in the loess area of northeastern Qinghai-Tibet Plateau,China.

Migration and speciation transformation mechanisms of mercury in undercurrent zones of the Tongguan gold mining area, Shaanxi Loess Plateau and impact on the environment

In order to study the migration and transformation mechanism of Hg content and occurrence form in subsurface flow zone of gold mining area in Loess Plateau and its influence on water environment,the field in-situ infiltration test and laboratory test were carried out in three typical sections of river-side loess,alluvial and proluvial strata in Tongguan gold mining area of Shaanxi Province,and the following results were obtained:(1)The source of Hg in subsurface flow zone is mainly caused by mineral processing activities;(2)the subsurface flow zone in the study area is in alkaline environment,and the residual state,iron and manganese oxidation state,strong organic state and humic acid state of mercury in loess are equally divided in dry and oxidizing environment;mercury in river alluvial or diluvial strata is mainly concentrated in silt,tailings and clayey silt soil layer,and mercury has certain stability,and the form of mercury in loess is easier to transform than the other two media;(3)under the flooding condition,most of mercury is trapped in the silt layer in the undercurrent zone where the sand and silt layers alternate with each other and the river water and groundwater are disjointed,and the migration capacity of mercury is far less than that of loess layer and alluvial layer with close hydraulic connection;(4)infiltration at the flood level accelerates the migration of pollutants to the ground;(5)the soil in the undercurrent zone is overloaded and has seriously exceeded the standard.Although the groundwater monitoring results are safe this time,relevant enterprises or departments should continue to pay attention to improving the gold extraction process,especially vigorously rectify the small workshops for illegal gold extraction and the substandard discharge of the three wastes,and intensify efforts to solve the geological environmental problems of mines left over from history.At present,the occurrence form of mercury in the undercurrent zone is relatively stable,but the water and soil layers have been polluted.The risk of disjointed groundwater pollution can not be ignored while giving priority to the treatment of loess and river alluvial landform areas with close hydraulic links.The research results will provide a scientific basis for water conservancy departments to groundwater prevention and control in water-deficient areas of the Loess Plateau.

Relationship Between Agriculture and Ecological Deterioration,Restoration and Reconstruction in Loess Plateau Areas of Northwest China

A comprehensive analysis was conducted on the current situation as well as historic succession processor agriculture and ecological conditions in Northwest China, in particular in the Loess Plateau, by means of a inter-disciplinary approach of ecology, agro-geohistory, and agronomy. It was concluded that the fundamental causes responsible for the ecological deterioration, signed by the poor agro-productivity and serious soil erosion, had been the extensive cropping system by ever-increasing reclamation on semi-drought slope land, where initiated a natural vegetation of brushy grasses with sparse trees, thus suitable only for animal husbandry. Based on an identification of specific actual status of China, several countermeasures of correctly dealing with the relationship between agricultural development and the ecological restoration and reconstruction were proposed, including to get breakthrough first in the transection area by means of the rational use of resources and the raising of agro-system productivity, to promoting 'water conservancy-type ecological agriculture' through the radical shift of traditional production pattern, and the adoption of a policy of proper degree of grain self-reliance, as well as to construct livestock industry base in Northwest China.

The effects of land use and its patterns on soil properties in a small catchment of the Loess Plateau

Due to relatively strong human activities in the hilly area of Loess Plateau, the natural vegetation has been destroyed, and landscape pattern based on agricultural land matrix was land use mosaic composing of shrub land, grassland, woodland and orchard. This pattern has an important effect on soil moisture and soil nutrients. The Danangou catchment, a typical small catchment, was selected to study the effects of land use and its patterns on soil moisture and nutrients in this paper. The results are as follows: The comparisons of soil moisture among seven land uses for wet year and dry year were performed: (1) the average of soil moisture content for whole catchment was 12.11% in wet year, while it was 9.37% in dry year; (2) soil moisture among seven land uses was significantly different in dry year, but not in wet year; (3) from wet year to dry year, the profile type of soil moisture changed from decreasing type to fluctuation-type and from fluctuant type to increasing type; (4) the increasing trend in soil moisture from the top to foot of hillslope occurred in simple land use along slope, while complicated distribution of soil moisture was observed in multiple land uses along slope. The relationships between soil nutrients and land uses and landscape positions were analysed: (1) five nutrient contents of soil organic matter (SOM), total N (TN), available N (AN), total P (TP) and available P (AP) in hilly area were lower than that in other areas. SOM content was less than 1%, TN content less than 0.07%, and TP content between 0.05% and 0.06%; (2) SOM and TN contents in woodland, shrub land and grassland were significantly higher than that in fallow land and cropland, and higher level in soil fertility was found in crop-fruit intercropping land among croplands; (3) soil nutrient distribution and responses to landscape positions were variable depending on slope and the location of land use types.

Land-use changes in the small watershed of the Loess Plateau,hilly-gully region, China

As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.

THE SYSTEMATIC DYNAMIC EMULATION ON THE AGRICULTURAL DEVELOPMENT ON THE LOESS PLATEAU

The Loess Plateau, covered with thick loess, lies in the middle reaches of the YellowRiver to the west of the Taihangshan Mountains, east of the Wuqiao Mountains south ofYinshan Mountains and north of the Qinling Mountains with a total area of 56×10~4km^2.The plateau is 1000--2500m above sea level and has loess as thick as 100--200 metres, be-

我国黄土高原地区地震动衰减关系研究的若干进展

地震动的衰减关系是指地震动随震级、距离和场地条件等变化的经验关系,近年来在我国亦被称为地震动预测方程,是估计地震动及其影响场的主要方法之一,在地震区划和重大工程场地地震安全性评价中被广泛应用。黄土是一种特殊土,在我国广泛分布。我国黄土高原地区地质构造复杂,新构造活动强烈,中强地震频发,地震动的衰减关系有其特殊性,总结我国黄土高原地区地震动衰减关系的研究成果对促进黄土高原地区抗震研究有重要意义。在简要介绍国内外地震动衰减关系研究的基础上,全面系统地总结我国学者在黄土高原地区的地震烈度衰减关系,基岩和土层场地地震动峰值加速度、峰值速度、峰值位移以及反应谱衰减关系方面的研究成果;评述和讨论在黄土覆盖地区地震动衰减研究领域存在的问题和今后的研究方向。文章的研究工作对从事黄土高原地区地震工程研究的科技人员有重要参考价值。

渭北黄土台塬区水库水下岸坡稳定形态预测模型研究

黄土地区水库塌岸预测仍以卡丘金法等经验图解法为主,此类方法预测结果的准确性取决于对岸坡剖面形态的准确描述。为了提高黄土地区水库塌岸宽度预测的准确性,选取渭北黄土台塬区选择典型水库进行现场调查,对原河道岸坡形态与蓄水后岸坡形态进行对比分析,在此基础上建立了水下岸坡形态预测模型。结果表明,渭北黄土台塬区水库岸坡塌岸稳定后,水上岸坡呈直立状,高度可达30 m以上,水下岸坡呈曲线形,受水深和岸坡高度共同影响,塌落物可能露出水面。在此基础上基于对数螺线方程建立了水下岸坡形态预测模型,并与经典图解法所用直线型岸坡进行对比,误差分析结果表明采用对数螺线方程进行水下岸坡形态预测时堆积体积误差为4.50%~39.70%,均值为12.64%,而直线型岸坡的预测误差为25.75%~124.69%,均值为75.69%。即采用对数螺线方程可以更好的测水下岸坡形态及水下堆积量。相关研究成果对黄土台塬区水库塌岸预测方法的改进,以及黄河流域的渭北黄土台塬区的环境保护与高质量发展具有实际意义。

从土壤保持角度探索全国生态桑产业发展布局

桑树具有十分强大的土壤保护功能。本文基于全国生态功能区划,瞄准生态桑在土壤保持生态系统服务功能中持续作用的重大科学问题,考量了桑树在各类生态重点区域的定位和价值实现途径。通过分析各生态区域蚕桑产业发展的基础状况,确定了西南喀斯特区、川滇干热河谷区、三峡库区、黄土高原区、鲁中山区和昆仑山区等6个桑树土壤保持核心服务区。针对上述6个桑树土壤保持核心服务区的产业生态特征,分别提出了保墒增碳、护土保水、保土降污、屯水治沙、肥土增碳和防风固沙的土壤管理技术,并推荐了广西宜州、四川盐边、重庆巫溪、陕西榆林、山东烟台和新疆和田等6个技术先行示范区。

自然和人为干扰因素对黄土高原生态环境质量变化的影响

为了识别自然和人为干扰因素对黄土高原生态环境质量变化的影响,以黄土高原为研究区,基于GEE平台和MODIS数据获取区域内2003-2022年的遥感生态指数(RSEI),利用随机森林识别自然因素和人为干扰因素对RSEI变化的驱动作用。结果表明:近20年内,(1)黄土高原的生态环境质量轻微改善,以0.002/a的速率增加,且生态环境质量空间分布总体呈由东南向西北递减的趋势,空间分布异质性较大,整体表现为良;蒙陕矿区和山西矿区大部分区域,以及黄陇矿区和宁东矿区的生态环境质量改善较为明显,占比分别为40.5%、25.7%、14.6%和19.9%,山西矿区和豫西矿区部分区域退化较为明显,占比分别为5.4%和34.3%。(2)黄土高原气温降低和升高区域分别占比46.3%和13.3%,而92.7%区域的降水不变;63.1%的土壤水、58.4%的地表径流和96.6%区域的地下水储量增加;98.5%区域的GDP增加,62.7%和20.9%区域的人口增加和降低,近70%的土地利用类型基本不变,其余区域的地物类型相互转换。(3)黄土高原RSEI改善区域主要受地表径流(占比39.8%)、地下水储量(15.7%)、GDP(13.4%)和气温(12.4%)的影响,退化区域主要受GDP(22.2%)、地表径流(21.3%)、地下水储量(16.4%)、气温(12.5%)和夜间灯光(10.5%)的影响;其次,RSEI改善的煤炭基地主要受地表径流和GDP的影响,退化的煤炭基地受GDP、夜间灯光、地下水储量和气温因素主导。综上所述,近20年内黄土高原生态环境得到改善,生态环境质量变化主要受地下水储量、地表径流、气温、夜间灯光、人口和GDP的影响。

黄土高原半干旱雨养农业区冬小麦气候适宜度评价——以通渭县为例

气候适宜度可以表征气候条件对作物生长发育的影响程度。利用黄土高原半干旱区通渭县近40 a气象资料和农业气象观测资料,基于模糊数学方法,根据冬小麦各发育时段对温度、水分、光照的需求,对黄土高原半干旱雨养农业区冬小麦全生育期气候适宜度进行评价。结果表明:通渭县近40 a冬小麦全生育期温度适宜度为0.58,停止生长—返青期的温度适宜度最高,达0.95,三叶期—停止生长的温度适宜度低,仅为-0.42,年际间差异小,全生育期温度适宜度以0.019/10 a的速率上升;水分适宜度为0.46,乳熟期—成熟期的水分适宜度最高,为0.66,其次为返青期—拔节期,为0.63,年际间差异大,全生育期水分适宜度以0.017/10 a的速率上升;光照适宜度为0.62,三叶期—停止生长和返青期—拔节期的光照适宜度最高,为0.68,乳熟期—成熟期最低,为0.51,全生育期光照适宜度以0.011/10 a的速率上升;综合适宜度为0.54,返青期—拔节期的综合适宜度最高,为0.70,三叶期—停止生长最低,为-0.36,全生育期综合适宜度以0.014/10 a的速率上升。冬小麦产量与抽穗期—乳熟期温度适宜度、乳熟期—成熟期水分适宜度、乳熟期—成熟期综合适宜度呈显著相关。气候适宜度能够较准确地反映出黄土高原半干旱雨养农业区冬小麦生育期内气象条件的优劣变化。

黄土高原彬长矿区土壤侵蚀特征及其与环境变化的关系

黄土高原矿区煤炭产量占全国70%以上,大规模开采活动导致区域内生态环境退化与土壤侵蚀加剧。然而,当前鲜有矿区土壤侵蚀时空特征及其与环境变化关系的定量研究,限制了煤矿区土地复垦与生态修复进展。为了探究矿区土壤侵蚀特征及其与环境变化的关系,为黄土高原煤矿区生态环境治理提供理论指导,该研究以彬长矿区为研究区,利用修订的通用土壤流失方程(revised universal soil loss equation,RUSLE)分别模拟了矿区全区2003—2019年及沉陷区2014—2019年土壤侵蚀速率,探究了矿区全区及沉陷区土壤侵蚀特征,定量研究了降雨、地形和植被对土壤侵蚀的影响。结果表明:1)2003—2019年间,彬长矿区土壤侵蚀速率整体呈显著上升趋势(P<0.05),年份间差异较大,2003年土壤侵蚀最为严重,侵蚀速率为85.56 t/(hm~2·a),2009年侵蚀程度最低,侵蚀速率为15.54 t/(hm^(2)·a)。微度、轻度侵蚀主要分布于城区、黄土塬和河流阶地等平坦地区,其空间分布在不同年份间基本保持一致,其余侵蚀类型主要分布于煤矿开采区、沟壑区及河道周边,且侵蚀强度空间异质性较大。2)2014—2019年间矿区全区及沉陷区土壤侵蚀速率表现出明显的季节周期性变化。春秋季节土壤侵蚀强度多表现为微度、轻度侵蚀,冬季侵蚀速率接近于0,夏季土壤侵蚀速率为一年中最高,是矿区水土流失治理的重点时段。3)彬长矿区土壤侵蚀速率与降雨量呈极显著正相关(P<0.01),沉陷区土壤侵蚀速率与降雨量、沉陷量及植被覆盖度均呈极显著正相关(P<0.01),降雨量是土壤侵蚀的主要影响因子,且开采沉陷加剧了土壤侵蚀,沉陷区的沉陷量不同,土壤侵蚀程度也不同。该研究方法探明了矿区的土壤侵蚀变化规律及环境变化对土壤侵蚀的影响,可为黄土高原煤矿区土壤侵蚀防治和生态环境恢复提供决策支持和科学依据。

微生物基因检测技术在鄂尔多斯盆地神府南气田勘探中的应用

针对鄂尔多斯盆地构造复杂,储层分布差异大,气藏富集规律不明等问题,本文采用微生物基因检测技术的荧光定量PCR法测量研究区样品中油气指示基因的丰度,同时利用高通量基因测序法检测样品中的烃类微生物种群类型,分析认为,本区主要有东北部、西部、南部三个烃类异常带,展布特征与沉积认识吻合,且西部、南部有亲缘关系,东北部与二者无亲缘关系,可能与致密气、煤层气不同层系烃的逸散有关。实钻表明,本技术对于鄂尔多斯盆地致密气和煤层气混源区的含油气性评价方面具有较好的适用性,为油气有利区带筛选提供参考依据。

陕北黄土高原沟壑区文物遗产时空分布规律研究

揭示陕北黄土高原沟壑区文物遗产的分布特征,为该地区历史文化时空变迁研究与历史文化空间格局的凝炼提供借鉴。研究将文物遗产按照其所承载的内涵分为聚居型、人文型、防御型与近现代文物遗产四类,运用地理信息技术分析其空间分布特征,结合历史、文化、社会等时空变迁脉络研究陕北黄土高原沟壑区文物遗产的时空分布规律及其影响因素,指出河流道路的位置与走向对聚居型文物遗产的分布具有较大影响,自然山川的形势决定了人文型文物遗产的选址与布局,政治军事活动推动了防御型遗产“由点至带”的发展演变。

黄土高原矿区生态系统服务价值的时空变化——以平朔矿区为例

开展矿区生态系统服务价值的时空分析对保护矿区生态环境、提升矿区生态系统功能具有重要意义。基于遥感数据和土地利用数据,采用3S技术、价值当量法和生态贡献度等方法,对黄土高原典型矿区——平朔矿区1990—2020年生态系统服务价值进行研究。结果表明:(1)1990—2020年平朔矿区6种土地利用类型面积变化迥异,耕地面积减少最大(1122.72 hm2),建设用地面积增加最大(2044.23 hm2)。(2)平朔矿区生态系统服务价值呈先下降后上升态势,由1990年的19562.43×104元减少到2010年的11265.40×104元,再增加到2020年的15755.47×104元,1990—2010年下降的主要原因是建设用地和草地的生态系统服务价值大幅减少,2010—2020年增加的主要原因是矿区实施了大量生态恢复治理工程。(3)1990—2020年平朔矿区除保持土壤价值增加外,其他各单项生态服务价值均有不同程度的减少,其中水源涵养、净化环境、生物多样性价值减少幅度较大,分别减少了115.84%、69.92%、18.29%。(4)1990—2020年平朔矿区生态系统服务价值的空间分布呈现南北高、中部低的特征。(5)平朔矿区草地、建设用地和林地的生态贡献度分别是-41.52%、-34.49%和-10.09%,三者是主要的贡献因子和敏感因子。

基于UAV-SfM方法的黄土高原砒砂岩区侵蚀监测算法比较

[目的]为比较地形变化监测算法在黄土高原砒砂岩区的适用性。[方法]以皇甫川流域特拉沟一支沟为研究对象,采用无人机摄影测量技术获取2022年7月至2023年3月影像,结合SfM技术生成三维点云数据,比较分析[digital elevation model of difference(DoD)、cloud to cloud(C2C)、cloud to mesh(C2M)、multiscale model to model cloud comparison(M3C2)]等4种算法的侵蚀产沙监测精度,并分析点云密度变化对各方法精度的影响。[结果](1)4种常用算法在空间上都能监测到大幅度地表变化。其中,以M3C2算法的结果最优,线性拟合结果最好(R^(2)=0.953,p<0.01),且综合误差最小(MAE=0.0161 m,MRE=3.37%,RMSE=0.0194 m),C2M算法其次,DoD算法再次,而C2C算法结果最差。(2)通过比较,DoD算法仅适用于平坦区域的快速检测,坡度陡峭的区域监测侵蚀沉积量存在高估的现象。(3)M3C2和C2C算法对点云密度变化敏感,而C2M和DoD受点云密度变化影响较小。[结论]研究结果可为黄土高原砒砂岩地区基于UAV-SfM的侵蚀产沙监测方法的选择提供参考。

西北黄土高原葡萄产区积雨节氮面源污染防控技术

西北黄土高原地表水资源贫乏,制约着葡萄产业的高质量可持续发展,氮肥过度施用,导致农业面源污染风险突出。为此,文章分析了西北黄土高原葡萄产区降雨和施肥的现状,并依据产区氮沉降情况,研发集成了西北黄土高原葡萄产区积雨节氮面源污染防控技术。3年相关数据分析结果表明,该技术3年累计可节水73430m^(3),累计减少尿素施用量130.5~1434.6kg,可显著减少因氮肥过量施用引起的面源污染风险,减少葡萄园生产成本。该技术在节水节氮、农业面源污染防控方面效果明显,可在整个西北黄土高原区推广应用。

黄土高原丘陵沟壑区玉米新品种引种比较综合评价

通过研究不同玉米品种在黄土高原丘陵沟壑区的稳产性及丰产性,以期为该区玉米新品种的筛选及推广提供科学依据。以引进10个玉米品种为试材,对参试各玉米品种的农艺性状、产量及产量特征等指标进行综合分析评价。结果表明,强盛399、伊丹131、金穗1915折合产量高,分别为11850.1、11605.0、11411.9 kg/hm2,较对照品种金穗702分别增产14.54%、12.17%、10.30%;并单39、丰田101、敦玉9号折合产量较低,分别较对照品种金穗702减产3.76%、10.86%、30.76%。利用综合评价法对参试玉米品种进行综合评价并结合产量结果表明,强盛399、金穗306、伊丹131、金穗702表现出良好的丰产性与稳产性,同时表现出静态稳定性高、品质优异、生态适应性强的特点,是适用于黄土高原丘陵沟壑区种植的玉米新品种,建议予以推广。金穗1915、FT806、强盛388综合评价居中,建议继续引种观察。敦玉9号、丰田101、并单39号综合评价较差,建议淘汰。

基于无人机摄影测量的黄土残塬沟壑区侵蚀沟监测技术研究

我国是世界上土壤侵蚀最严重的国家之一,尤其是西北黄土高原的水土流失最为显著。本文通过利用无人机搭载激光雷达对山西省临汾市吉县中垛塬进行土壤侵蚀动态监测,建立三维模型,得出侵蚀沟形态特征的变化量,即侵蚀沟的扩张量。并通过在所选侵蚀沟的沟头处布设测钎,监测暴雨前后测钎高度的变化,对无人机监测结果进行验证。研究显示,侵蚀沟无人机遥感监测技术的应用,能全面提高侵蚀沟监测的技术水平,提升监测工作效率,值得在侵蚀沟监测中推广使用。