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黄河中游多沙粗沙区流域坡面水保措施变化特征 总被引：1，自引：0，他引：1
选用Landsat TM、环境星CCD、SPOT4 和资源三号卫星影像等多源地学数据,通过人机交互式解译和修订土地利用与梯田数据,提出用相邻图幅递进回归分析法消除NDVI时相差异后反演植被盖度,构建起退耕还林还草面积比例、植被盖度均值变化量和有效梯田累计保存面积比例3 个坡面特征变化指示参数后,运用综合聚类分析和多要素贡献率模型研究黄河中游多沙粗沙区的流域坡面水保措施变化特征。结果表明：（1） 1998-2010 年间研究区内流域坡面水保措施变化显著,平均退耕还林还草面积比例为5.55%,平均林草植被盖度均值增加20.63%,平均有效梯田累计保存面积比例达6.25%;（2） 多要素水保措施变化共同作用下的流域坡面变化特征主要有7 种类型,即植被盖度变化主导型、植被—土地变化主导型、土地—植被变化主导型、植被—梯田变化主导型、梯田—植被变化主导型、梯田面积变化主导型和多要素变化共同主导型;（3） 不同类型的空间分布存在一定的地貌背景差异,后续研究应结合流域坡面变化特征及其地貌格局来优化配置水保措施,并合理估计水沙模型模拟的敏感性参数。 相似文献
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运用渭河流域24个气象站点日降雨数据对2001~2012年热带测雨卫星(TRMM)3B42数据在不同子流域、不同降雨强度以及不同时间尺度的精度进行了对比验证,并对比分析了基于TRMM和站点数据的渭河流域降雨时空分布特征。结果显示:在不同子流域的日TRMM数据比站点观测数据对低值降雨更为敏感,而在极大值降雨数据观测上两者差距较大,月尺度TRMM站点观测数据确定性系数在0.89到0.96之间;两种数据在流域降雨的时空分布上表现一致性,在年内6月中旬~10月初为湿润多雨期,其余月份降雨较少,空间分布呈东南部大,西北部小的格局。 相似文献
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分别利用分布式时变增益水文模型（DTVGM）和分布式耗水过程模型（DEPM）对延河流域延安水文站以上区域进行水文过程模拟,并应用拓展卡尔曼滤波(EKF)算法对2个模型的绿水(实际蒸散发)模拟结果进行同化处理,从而优化了研究区的绿水量并得出绿水的空间分布规律。结果表明：在整个模拟期,DTVGM的月尺度效率系数（NSCE）达到了0.83,水量平衡相对误差为-1.97%,模型能够较好地模拟研究区的水文过程;DEPM的水量平衡相对误差为-1.81%,能较好地模拟流域的水量平衡;DTVGM和DEPM模拟的流域2010年平均绿水量分别为378.52 mm和375.55 mm,空间分布格局相似。与站点观测值比较,DTVGM和DEPM模拟绿水的NSCE分别是0.76和0.59,DEPM的结果具有更多的空间变化信息。同化结果表明EKF算法能综合优化2个模型的模拟结果,同化后DTVGM模拟研究区的平均绿水量为376.34 mm,NSCE为0.78;同化后研究区绿水标准差为40.37 mm,比同化前增加了7.79 mm,绿水空间分布体现了更多的空间变化信息,同时,空间分布时格局也更加合理。 相似文献
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Soil erosion has become a significant environmental problem that threatens ecosystems globally. The risks posed by soil erosion, the trends in the spatial distribution in soil erosion, and the status, intensity, and conservation priority level in the middle reaches of the Yellow River Basin were identified from 1978 to 2010. This study employed a multi-criteria evaluation method integrated with GIS and multi-source remote sensing data including land use, slope gradient and vegetation fractional coverage(VFC). The erosion status in the study region improved from 1978 to 2010; areas of extremely severe, more severe, and severe soil erosion decreased from 0.05%, 0.94%, and 11.25% in 1978 to 0.04%, 0.81%, and 10.28% in 1998, respectively, and to 0.03%, 0.59%, and 6.87% in 2010, respectively. Compared to the period from 1978 to 1998, the area classed as improvement grade erosion increased by about 47,210.18 km2 from 1998 to 2010, while the area classed as deterioration grade erosion decreased by about 17,738.29 km2. Almost all severe erosion regions fall in the 1 st and 2 nd conservation priority levels, which areas accounted for 3.86% and 1.11% of the study area in the two periods, respectively. This study identified regions where soil erosion control is required and the results provide a reference for policymakers to implement soil conservation measures in the future. 相似文献
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In areas with topographic heterogeneity, land use change is spatially variable and influenced by climate, soil properties, and topography. To better understand this variability in the high-sediment region of the Loess Plateau in which soil loss is most severe and sediment diameter is larger than in other regions of the plateau, this study builds some indicators to identify the characteristics of land use change and then analyze the spatial variability as it is affected by climate, soil property, and topography. We build two indicators, a land use change intensity index and a vegetation change index, to characterize the intensity of land use change, and the degree of vegetation restoration, respectively. Based on a subsection mean method, the two indicators are then used to assess the spatial variability of land use change affected by climatic, edaphic, and topographic elements. The results indicate that: 1) Land use changed significantly in the period 1998–2010. The total area experiencing land use change was 42,302 km2, accounting for 22.57%of the study area. High-coverage grassland, other woodland, and forest increased significantly, while low-coverage grassland and farmland decreased in 2010 compared with 1998. 2) Land use change occurred primarily west of the Yellow River, between 35 and 38 degrees north latitude. The four transformation types, including(a) low-coverage grassland to medium-coverage grassland,(b) medium-coverage grassland to high-coverage grassland,(c) farmland to other woodland, and(d) farmland to medium-coverage grassland, were the primary types of land use change, together constituting 60% of the area experiencing land use change. 3) The spatial variability of land use change was significantly affected by properties of dryness/wetness, soil conditions and slope gradient. In general, land use changed dramatically in semi-arid regions, remained relativelystable in arid regions, changed significantly in clay-rich soil, remained relatively stable in clay-poor soil, changed dramatically in steeper slopes, and remained relatively stable in tablelands and low-lying regions. The increase in vegetation coincided with increasing changes in land use for each physical element. These findings allow for an evaluation of the effect of the Grain to Green Program, and are applicable to the design of soil and water conservation projects on the Loess Plateau of China. 相似文献
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To control soil erosion and restore the degraded environment in the Loess Plateau, a large number of measures related to soil and water conservation have been employed that have profoundly affected catchment properties. This study constructed three indicators to characterize changes to the catchment slope, proposed both a method for a regression analysis of adjacent images and a sequence model, and applied multisource remotely sensed images and GIS spatial clustering analysis technologies to extract thematic information and comprehensively analyze the catchment change characteristics. The results indicate that the catchment slope properties changed significantly. At catchment scale, the average values of ARC, DVC and ART were 6.43%, 25.57% and 4.30%, respectively. There were six clustering types of catchment slope property changes. The maximum and minimum of the average similarities of the clustering types were 0.992 and 0.935. Each slope control measures had a distinct effect on catchment slope; the dominating factor of each clustering type was identified as: Type 1: D-VC, Type 2: D-VCLU, Type 3: D-LUVC, Type 4: D-TAVC, Type 5: D-TAC and Type 6: D-MFC. Type 5 and Type 1 covered the largest areas, respectively occupying 37.28% and 31.01%. Catchment slope property changes also had distinct types that depended on their geomorphological conditions. These findings provide a useful basis from which to further study catchment slope hydrological and soil erosion processes. 相似文献
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The objective of this study is to quantitatively evaluate Tropical Rainfall Measuring Mission(TRMM) data with rain gauge data and further to use this TRMM data to drive a Distributed Time-Variant Gain Model(DTVGM) to perform hydrological simulations in the semi-humid Weihe River catchment in China.Before the simulations,a comparison with a10-year(2001-2010)daily rain gauge data set reveals that,at daily time step,TRMM rainfall data are better at capturing rain occurrence and mean values than rainfall extremes.On a monthly time scale,good linear relationships between TRMM and rain gauge rainfall data are found,with determination coefficients R~2 varying between 0.78 and 0.89 for the individual stations.Subsequent simulation results of seven years(2001-2007)of data on daily hydrological processes confirm that the DTVGM when calibrated by rain gauge data performs better than when calibrated by TRMM data,but the performance of the simulation driven by TRMM data is better than that driven by gauge data on a monthly time scale.The results thus suggest that TRMM rainfall data are more suitable for monthly streamflow simulation in the study area,and that,when the effects of recalibration and the results for water balance components are also taken into account,the TRMM 3B42-V7 product has the potential to perform well in similar basins. 相似文献
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基于19822010年无定河流域的遥感影像、气象和土地利用数据,利用Priestley-Taylor公式计算出潜在蒸散发,进而得到干旱指数,将各气象因子与干旱指数差值进行叠加、逐象元相关分析,得到了无定河流域19822010年干旱指数的时空变化,并分析了气候和土地利用变化对干旱指数变化的影响。结果显示:（1）1982年、2010年干旱指数分别为2.01和2.13,总体趋势是趋干旱的;（2）干旱指数2.0以下的区域迅速减少,2.15以上的区域明显扩张;（3）干旱指数均呈现增加趋势,显著增加的区域集中于无定河流域中游和下游地区;（4）干旱指数变化同气温、水汽压、净辐射的变化成正相关,同降水量变化成负相关;（5）各种土地利用类型的干旱指数均呈现增长趋势,但是增长的幅度有所不同:林地>耕地>草地>建筑用地>水域>未利用地。（6）土地利用对干旱指数平均值的影响非常微弱,干旱指数的变化主要是由于气候变化导致的。 相似文献
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黄河中游多沙粗沙区（渭河段）土地利用对植被盖度的影响 总被引：3，自引：0，他引：3
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。 相似文献
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