陕北多沙粗沙区乡村聚落土壤侵蚀研究

对陕北多沙粗沙区乡村聚落中庭院、户间道路和户间空地的土壤侵蚀状况研究表明,户间道路侵蚀强度最强,其次为户间空地,庭院最小。进一步分析侵蚀泥沙中>0.05mm粗颗粒和<0.01mm细颗粒的含量与平均泥沙含量的关系说明,户间道路径流挟沙能力强,因而侵蚀强度最大;庭院水流平缓,挟沙能力最小,其侵蚀强度最小,而户间空地侵蚀强度居于二者之间。说明在加强治理黄土高原土壤侵蚀治理的同时,应特别重视乡村聚落户间道路的土壤侵蚀问题。     

京津水源区坡耕地土壤侵蚀特征分析

坡耕地是保障粮食安全与经济发展的重要资源.本文利用承德市南山径流场资料对不同坡长下径流深、含沙量及侵蚀量进行对比分析,结果显示:坡长和降雨强度都对土壤侵蚀有影响,随着坡长变化,导致土壤侵蚀量变化的两个主导因素不断变换.雨强小于0.25 mm/min时,坡面土壤侵蚀模数随坡长的增加而增大;雨强大于0.25mm/min时,随坡长的增加先增大后减小,最大侵蚀量总是出现在22 m坡长范围内.径流深均值与侵蚀量增量随坡长变化趋势一致,含沙量均值变化与雨强关系密切.所以治理京津水源区坡耕地水土流失,应在22 m坡长以内采取等高植物篱等措施,既可降低工程投入,又减少坡面土壤流失,提高土地生产力.     

黑土坡耕地土壤流失形态分析——以一次降雨为例

以东北黑土区典型漫岗坡耕地为研究对象,测定次降雨条件下整个集水盆地出口处的径流体积及其含沙量,研究侵蚀泥沙的粒径分布特征、碳氮富集度以及可溶性养分的流失状况。结果表明,研究区只有在强降雨的情况下才会在集水盆地尺度上发生水土流失现象。20.5 mm降雨条件下(2006年8月1日)径流泥沙含量为1.0～2.5 g/L,泥沙C、N富集系数分别为2.10和3.31。径流液中DOC的浓度介于2.47～3.93 mg/L之间,TN浓度介于1.61～3.28 mg/L之间,径流携带养分量在整个养分流失过程中是不可忽视的流失途径。侵蚀泥沙(未加分散剂)的团聚体组成和原土壤有很大差异,径流泥沙的流失主要是粒径为0.053 mm以下的团聚体,尤其是0.002～0.02 mm的粉粒团聚体为主。     

延安、榆林黄土丘陵沟壑区乡村聚落土地利用研究

在实地调查的基础上 ,将该区乡村聚落划分为 4种类型 ,论述了乡村聚落的特点 ,分析了聚落用地情况 ,其中院落用地较大 ,占聚落总用地的 41 .2 5 %～ 5 8.62 % ,人口密度大的绥德、米脂地区 ,户均聚落占地较少 ( 4 0 3.6m2 ) ,而人口密度小的榆阳区户均聚落占地较多 ( 4 84m2 ) ,乡村聚落实际占地比一般统计数字大 5 0 .6% ,同时聚落用地数量在不断增大 ,并向条件好的地方迁移     

不同作物间坡面径流和泥沙流失量特征与差异分析

为了揭示作物种类对坡面径流和泥沙流失的影响,对坡耕地玉米、莜麦和土豆三种作物小区在7~9月侵蚀性降雨期的降雨量、径流量和泥沙流失量进行了监测与分析。结果表明:2015年7~9月侵蚀性降雨单场降雨量在25.76~40.25mm之间,均值为31.49mm,属大雨。作物种类对坡面径流量影响显著,表现为莜麦地>土豆地>玉米地,均值分别为:41.45L、37.48L和30.84L。三种作物小区泥沙流失量与降雨量和径流量间成正向线性关系,但相关系数和斜率均存在差异。随着径流量的增加,玉米小区泥沙流失量增加最慢,莜麦小区居中,土豆小区最快。三种作物小区径流含沙率存在显著差异,表现为:土豆小区>莜麦小区>玉米小区,均值分别为150.22g/L、121.47g/L和52.36g/L。作物种类对坡耕地坡面径流量、泥沙流失量、径流含沙率以及它们间相互关系均有影响,但玉米比莜麦和土豆具有更强的调蓄径流和保护泥沙流失的作用。     

基于水土流失评价的高寒草甸经营模式比较

选择甘肃省单户草地经营为主的天祝县和联户经营为主的合作市为研究区,采用RS和GIS技术并根据RULSE土壤流失模型,计算两地10 a间(2004—2014年)的草地土壤侵蚀模数,研究两地降雨、农牧业人口、家畜数量和畜牧业产值与水土流失的相关性,并用排除法分析造成两县草地土壤侵蚀模数差异的原因。结果显示:(1)天祝县和合作市土壤侵蚀现状以微度侵蚀为主;(2)天祝县年均土壤侵蚀模数比合作市高7. 21 t·a~(-1)·km~(-2),10余年土壤侵蚀增加速率为合作市的4倍,各草地类型平均土壤侵蚀模数比合作市增长更快;(3)天祝县年降雨量与草地平均土壤侵蚀模数成显著正相关(R=0. 737,P 0. 05),合作市农牧业人口与草地平均土壤侵蚀模数成显著负相关(R=-0. 829,P 0. 05);(4)两县草地平均侵蚀模数差值与年降雨量差值不存在相关性(P 0. 05),合作市家畜超载率高于天祝县。认为草地经营模式是造成草地退化、水土流失的主要原因,且草地联户经营模式在防止水土流失方面优于单户经营模式。     

Geo-CA与GIS在区域土壤侵蚀动态监测与模拟中的应用

动态监测和模拟土壤侵蚀的发育及演化过程,对于区域水土保持与环境修复工作意义重大。以黄土丘陵区魏沟流域为例,基于遥感融合影像和GIS技术,采用通用土壤流失方程,计算了其1998年和2004年的土壤侵蚀量,并分析了土壤侵蚀与其环境背景的空间关系;在此基础上,构建了与ArcView软件平台集成的地理元胞自动机,模拟了该流域2004年和2010年土壤侵蚀空间演化情形。结果表明:流域2004年平均土壤侵蚀模数为9242.5 t/(km2.a),1800~1900 m的海拔高程带、15~25°坡度带和南坡是发生土壤侵蚀的主要区域;经模拟,2010年总侵蚀面积为120.65 km2,侵蚀总量1.21×106t,土壤侵蚀状况总体上将有所减缓。     

榆林市还林还草后土壤保持功能和经济价值评价

为了定量评估退耕还林还草工程在黄土高原核心区的土壤保持能力和经济价值,以榆林市12个县市为研究对象,利用USLE土壤侵蚀模型结合RS、GIS技术,估算了2000—2013年榆林市土壤侵蚀模数,在此基础上评估了土壤保持能力的变化,利用市场价值法、机会成本法和影子工程法估算了其经济价值。结果表明:14 a来榆林市土壤侵蚀强度呈现降低趋势,2013年比2002年平均侵蚀模数减少784.82 t·km-2·a-1,土壤流失总量减少4.20×107t。土壤保持能力明显提高,但空间差异明显,南部丘陵沟壑区较西北部风沙区土壤保持能力明显提高。2013年土壤保持能力从大到小依次是林地41 540.00 t·km-2·a-1、草地34 852.71 t·km-2·a-1、耕地29 679.39t·km-2·a-1、未利用土地7 973.03 t·km-2·a-1。2013年土壤保持能力为33 685.89 t·km-2·a-1、潜在侵蚀总量为1.61×109t,土壤保持总量约为1.43×109t。为了消除年际降雨侵蚀力不同对土壤侵蚀造成的影响,利用模拟降雨法,模拟了2013年在2002年降雨条件下的土壤保持能力为37 303.64 t·km-2·a-1,比2002年增加1 423.54 t·km-2·a-1。土壤总保持量为1.58×109t,比2002年多出7.20×107t,N、P、K元素共增加了8.24×104t。2013年和2002年土壤保持总价值分别为1.49×1010元和1.51×1010元,增加了5.90×108元。退耕还林还草工程在榆林市取得了显著的生态经济价值,该研究结果可以为该地区土壤保持能力与生态管理提供一定的参考。     

沙漠-黄土过渡带风水复合侵蚀营力特征——以靖边县为例

以北京师范大学陕西省靖边县榆林风沙科学野外实验站自动气象站2007-2009年的降雨、风速和风向数据为基础,分析沙漠-黄土过渡带风水复合侵蚀营力的特征。结果表明：① 研究区年内降雨量≥12 mm的降雨事件主要分布在5-9月,月平均降雨侵蚀力8月最大,为318.24 MJ·mm/(hm²·h·a),年平均降雨侵蚀力为510.08 MJ·mm/(hm²·h·a);② 该区西北风占主导地位,东南风次之,累计频率分别为43.8%和16.21%;起沙风主要集中在3-6月,其频率分别为19.34%、12.34%、20.5%、12.39%;③ 研究区年平均输沙势（DP）、合成输沙势（RDP）分别为228.76 VU、41.73 VU,合成输沙方向（RDD）为141.17°,方向变率指数（RDP/DP）为0.2,起沙风变率较大,属于中等风能环境,沙物质向东南偏南方向输移。     

黄土区土质道路径流水动力学参数的灰色关联度分析

黄土区土质道路路面侵蚀是该地区土壤侵蚀中的重要形式之一,为了探讨其土壤剥蚀率与径流水动力学参数的相关关系,以便为该地区道路土壤侵蚀预报模型的建立提供帮助,采用室内人工降雨及放水冲刷实验、灰色关联度分析方法研究了裸露土质路和植草土质路的径流水动力学参数与土壤剥蚀率间的关系,结果表明:1)在15°坡度、不同雨强条件下,可根据径流量或水流功率计算土壤剥蚀率;2)在2mm.min-1雨强、不同坡度条件下,可根据水流功率或坡度计算土壤剥蚀率;3)在降雨加放水冲刷试验条件下,裸露土质路的土壤剥蚀率可通过径流水深或径流流速计算得出,而植草土质路的土壤剥蚀率可通过过水断面单位能量或径流量计算得出。因此,在无汇水条件时,根据径流水流功率计算土壤剥蚀率较为合理;在有汇水条件时,采用径流量计算土壤剥蚀率较为合理。     

Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China.Understanding the composition,distribution,and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion.In this study,based on laboratory rainfall simulation experiments,we analyzed rainfall-induced erosion processes on sand-covered loess slopes(SS)with different sand cover patterns(including length and thickness)and uncovered loess slopes(LS)to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion.The grain-size curves of eroded sediments were fitted using the Weibull function.Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS.The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed.The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS.Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes.The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage.Sand cover on loess slopes aggravates loess erosion,not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess,compared with the loess slopes without sand cover.The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount.Furthermore,given the same sand cover pattern,a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion.This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.     

Transport mechanism of eroded sediment particles under freeze-thaw and runoff conditions

Hydraulic erosion associated with seasonal freeze-thaw cycles is one of the most predominant factors, which drives soil stripping and transportation. In this study, indoor simulated meltwater erosion experiments were used to investigate the sorting characteristics and transport mechanism of sediment particles under different freeze-thaw conditions (unfrozen, shallow-thawed, and frozen slopes) and runoff rates (1, 2, and 4 L/min). Results showed that the order of sediment particle contents was silt>sand>clay during erosion process on unfrozen, shallow-thawed, and frozen slopes. Compared with original soils, clay and silt were lost, and sand was deposited. On unfrozen and shallow-thawed slopes, the change of runoff rate had a significant impact on the enrichment of clay, silt, and sand particles. In this study, the sediment particles transported in the form of suspension/saltation were 83.58%-86.54% on unfrozen slopes, 69.24%-84.89% on shallow-thawed slopes, and 83.75%-87.44% on frozen slopes. Moreover, sediment particles smaller than 0.027 mm were preferentially transported. On shallow-thawed slope, relative contribution percentage of suspension/saltation sediment particles gradually increased with the increase in runoff rate, and an opposite trend occurred on unfrozen and frozen slopes. At the same runoff rate, freeze-thaw process had a significant impact on the relative contribution percentage of sediment particle transport via suspension/saltation and rolling during erosion process. The research results provide an improved transport mechanism under freeze-thaw condition for steep loessal slopes.     

山区农村聚落空心化的初步研究

与平原或低丘陵地区相比,黄土丘陵地区农村聚落空心化表现出农村聚落空心化比例较高、新扩带与空化带的界限相当模糊、新建住房沿交通线和山脚展布、破坏和浪费的土地数量更多等特点。农村聚落空心化不仅破坏了农村聚落生态环境,而且加剧了黄土丘陵地区的水土流失,也使以窑洞景观为典型特征的村镇形态有消失的危险。农村聚落空心化涉及农村社会经济的许多方面,因此其对策研究要重视在农村聚落空心化的生命周期与中国城市化的背景下,从多层次多角度深入地揭示农村聚落空心化的时空变化特征和本质规律,为建设社会主义新农村提供科学依据。     

Effect of soil management on soil erosion on sloping farmland during crop growth stages under a large-scale rainfall simulation experiment

Soil erosion on farmland is a critical environmental issue and the main source of sediment in the Yellow River, China. Thus, great efforts have been made to reduce runoff and soil loss by restoring vegetation on abandoned farmland. However, few studies have investigated runoff and soil loss from sloping farmland during crop growth season. The objective of this study was to investigate the effects of soil management on runoff and soil loss on sloping farmland during crop growth season. We tested different soybean growth stages (i.e., seedling stage (R1), initial blossoming stage (R2), full flowering stage (R3), pod bearing stage (R4), and initial filling stage (R5)) and soil management practice (one plot applied hoeing tillage (HT) before each rainfall event, whereas the other received no treatment (NH)) by applying simulated rainfall at an intensity of 80 mm/h. Results showed that runoff and soil loss both decreased and infiltration amount increased in successive soybean growth stages under both treatments. Compared with NH plot, there was less runoff and higher infiltration amount from HT plot. However, soil loss from HT plot was larger than that from NH plot in R1-R3, but lower in R4 and R5. In the early growth stages, hoeing tillage was effective for reducing runoff and enhancing rainfall infiltration. By contrast, hoeing tillage enhanced soil and water conservation during the late growth stages. The total soil loss from HT plot (509.0 g/m²) was 11.1% higher than that from NH plot (457.9 g/m²) in R1-R5. However, the infiltration amount from HT plot (313.9 mm) was 18.4% higher than that from NH plot (265.0 mm) and the total runoff volume from HT plot was 49.7% less than that from NH plot. These results indicated that crop vegetation can also act as a type of vegetation cover and play an important role on sloping farmland. Thus, adopting rational soil management in crop planting on sloping farmland can effectively reduce runoff and soil loss, as well as maximize rainwater infiltration during crop growth period.     

榆林市参考作物蒸发蒸腾量随时间序列变化的规律

根据选取的榆林市5个代表气象站1985~2006年22年的气象资料,应用FAO-Penman-Monteith公式计算了各站历年各月的参考作物蒸发蒸腾量(ETo),并分析了ETo随时间序列变化的规律。结果表明:榆林市5个代表站5、67、月份的ETo之和占全年的比例最大;各代表站的ETo主要在1996年以后随时间呈极显著增加趋势,在1985~1996年,定边、横山的ETo随时间呈极显著减少的趋势,绥德、榆阳、神木的ETo随时间呈极显著增加的趋势,但是增加的趋势线斜率均小于1996年以后的趋势线斜率;榆林市的ETo与平均气温、日照时数、风速呈极显著的正相关,与相对湿度呈极显著的负相关;ETo与最高气温呈显著正相关,与最低气温除了定边站呈极显著正相关外,与其它各站均呈极显著负相关;平均气温是影响榆林市ETo变化的主要气象因子。     

巴图湾水库风沙入库量的估算

风沙入库给干旱、半干旱地区的水库带来了严重的填淤危害。本文通过对内蒙古乌审旗南部巴图湾水库岸边流动沙丘不同部位风速与风沙流的同步观测,计算出库岸流动沙丘表面的平均输沙率。利用巴图湾水库1986~2005年9月份的5期TM遥感影像统计出水库两岸受不同风向影响的流动沙丘断面的平均长度,结合巴图湾水库附近乌审旗河南乡气象站1985~2004年的气象资料,统计出不同风向大于起沙风的风速年均持续时间,初步计算出巴图湾水库的年均入库风沙量。结果表明:(1)巴图湾水库的年均入库风沙量为3.65万t,其中西岸风沙入库量为3.55万t,东岸为0.10万t。西岸风沙危害最为严重,是治沙工作的重点。(2)巴图湾水库的风沙入库具有明显的时间性和方向性。受季风气候的影响,风沙入库的方向会随着风向的变化而改变。东南风与西北风是造成东西两岸风沙入库的主要风向。西北风对风沙入库量的贡献最大。(3)在大于起沙风的风速中,5~12 m/s风速段是风沙入库的主要风速。当风速中7 m/s以上的风速持续时间有一个较小的增加时,入库风沙量将会有一个巨大的增加。(4)库岸半固定沙丘的风沙入库,降尘和风水复合侵蚀引起的库岸坍塌也是入库风沙量的重要组成部分。因此,巴图湾水库的实际年入库风沙量应该大于3.65万t。     

陕北地区气温突变及其对旱涝灾害的影响

利用陕北地区1959～2009年50年以来延安、榆林、定边、吴旗、横山、绥德等6个气象站点的逐年气温、降水资料,通过年平均气温距平变化、非参数Mann-Kendall检验方法,对陕西省陕北地区气温年平均温度变化、年平均最高气温变化、年平均最低气温变化特征进行了分析,揭示了陕北地区近50年来气温变化趋势,并且结合陕北地区...     

神府—东胜矿区土地沙漠化及其对入黄泥沙的影响

根据野外实际调查和实验,运用遥感制图和统计量测,本文系统地研究神府—东胜矿区的土地沙漠化的环境背景,形成演变及危害的现状和发展趋势。矿区现有沙漠化土地面积1956平方公里,占总面积的57％。年风沙入河沙量3483.46万吨。预计矿区开发将新增沙漠化土地232.78平方公里,其中一、二期工程新增沙漠化土地面积193.1平方公里。新增入河沙量479.47万吨/年。指出防治沙漠化的原则和措施,可供矿区开发和治黄参考。     

Lithic soils in the semi-arid region of Brazil: edaphic characterization and susceptibility to erosion

Soils(Leptosols or Epileptic Regosols)with lithic contact at a depth of 50 cm occupy almost 20%of the Brazilian semi-arid region.These lithic soils are susceptible to erosion due to faster saturation of water-holding capacity during rainfall,which accelerates the beginning of runoff.However,erosion traits of lithic soils in the semi-arid region of Brazil are less studied.The aim of this study was to characterize the soil and landscape attributes in areas with Neossolos Litólicos(Entisols)in the Caatinga biome to identify region of high susceptibility to erosion.Results showed that the soils were characterized by a sandy texture,soil structure with poor development and low content of organic carbon.These attributes increase susceptibility to erosion and reduce water storage capacity,especially in the states of Cearáand Sergipe.In these states,the content of rock fragments in the soil reaches 790 g/kg.High contents of silt and fine sand,high silt/clay ratio,predominance of Leptosols and strong rainfall erosivity were observed in Piauíand northwestern Ceará.A very high degree of water erosion was observed in the states of Pernambuco and Paraíba.Despite the low degree of erosion observed in the state of Bahia,it is highly susceptible to erosion due to the predominance of very shallow soils,rugged relief and high values of rainfall erosivity.Lower vulnerability was observed in the state of Alagoas because of its more smoothed relief,greater effective soil depth,thicker A horizon of soil and lower rainfall erosivity.In general,the characteristics that intensify the susceptibility to erosion in the Caatinga biome are those soil structures with poor development or without aggregation,low contents of organic carbon,high contents of silt and fine sand,high values of silt/clay ratio and rugged relief in some regions.This study collected information contributing to a better characterization of soils with lithic contact in the semi-arid region of Brazil.In addition,regions with a higher susceptibility to erosion were identified,revealing insights that could help develop strategies for environmental risk mitigation.