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1.
在长江和黄河源区的左冒西孔曲和纳通河、垮热洼尔玛河流域的不同植被覆盖下建立了天然径流观测场,利用观测天然降水和人工模拟降水,初步研究了江河源区不同植被覆盖下降水的产流产沙效应。结果表明,长江黄河源区的3个小流域内,在典型高寒草甸草地30°坡面上,退化较为严重的30%覆盖度以下的场地内,地表径流产出量明显大于覆盖度较好的95%、92%和68%场地,同时产沙量显著高于这3个场地,其平均单次降水形成的泥沙量是这三种盖度的2~4倍,由此造成地表侵蚀量平均为这3种盖度的3~10倍。通过对几次典型的降水形态的分析,在长江黄河源区高寒草甸草地的坡面上,不但降水量影响着产流产沙量,降水形态也影响着产流产沙量,降雨仍是引起水土流失的主要降水形态,在降水量相同的条件下,降雪可比降雨和雨加雪增加产流量2.1~3.5倍,可比降雨减少泥沙侵蚀45.4%~80.3%。人工模拟结果表明:对于覆盖度为5%和30%的强度退化草地,次降水量在3.5 mm时,就形成了较为明显的径流和产沙效应,当次降雨量达到7 mm,降雨持续时间15 min,5 m2场地内就会形成1 400 mL以上的径流量;在地表土壤含水量(FDR测0~5 cm平均含水量为36.7%)较高的情况下,次降雨量达4mm,降雨强度超过0.4 mm/min,在5 m2场地内历时5 min就能形成1 060 mL的地表径流,每100 mL径流中含泥沙高达1.6 g。这一试验结果在长江黄河源区3个不同的河源小流域是一致的。 相似文献
2.
长江源区不同植被覆盖下产流产沙效应初步研究 总被引：15，自引：2，他引：13
在长江源区北麓河支流左冒西孔曲流域建立了不同植被覆盖下的天然径流观测场,观测天然降水和人工模拟降水在相同坡度不同植被覆盖下降水的产流产沙效应.结果表明:在典型高寒草甸草地30°坡面上,相同降水条件下,30%覆盖度的场地的地表径流产出量明显大于覆盖度92%和68%两个场地,同时产沙量也显著高于两个高盖度场地的,平均单次降水形成的泥沙量是后两种情形的2~4倍,由此造成地表侵蚀量平均为后两种情形的3~10倍;但在相同降水条件下,92%高盖度场地产生的径流量比68%盖度场地产生的径流量大,产沙量刚好相反.不同降水形态对于下垫面产流产沙过程也具有明显影响,无论下垫面状况如何,在几种降水形态中,降雪融水的产流量最大,产沙量最小.人工模拟的结果表明,对于覆盖度<68%的中、强度退化草地,次降水量在3.5 mm时,就形成了较为明显的径流和产沙效应.当次降雨量达到7.2 mm,降雨持续时间30 min,覆盖度为30%、68%和92%的25 m2场地分别形成2885 mL、2450 mL和1030 mL的径流量;覆盖度<30%的退化草地泥沙含量明显高于高覆盖度的,相同降水形成的平均泥沙含明显高于高覆盖度的, 相同降水形成的平均泥沙含量高达2~7倍. 相似文献
3.
The 137Cs tracer technique was used to study soil erosion of alpine meadow grassland in two small river basins in the headwater region
of the Yellow River. The results show that the levels of 137Cs in soil samples from this alpine meadow vegetation zone exhibit an exponential distribution, generally within a depth of
approximately 20 cm. Due to strong winds, freeze-thaw cycles and water, soil erosion was found to be stronger on the upper
slope than on the lower slope, and except for the slope crest, the intensity of soil erosion at other sites was as follows:
upslope < midslope < downslope. There was a significant negative correlation between the intensity of soil erosion and the
extent of alpine meadow vegetation cover (P < 0.01). The mean soil erosion modulus exhibited a linear reduction trend with an increase in vegetation cover, and the correlation
coefficient R
2 was ≥ 0.997. The higher the degradation degree of the alpine meadow grassland, the greater is the soil erosion. The mean
erosion modulus in the severely degraded meadow zone was 2.23 times greater than the one in the slightly degraded zone, and
the maximum erosion modulus reached 2.96 × 106 kg/km2/a. 相似文献
4.
Climatic causes of ecological and environmental variations in the source regions of the Yangtze and Yellow Rivers of China 总被引：1，自引：0，他引：1
In the source regions of the Yangtze and Yellow Rivers of China, glaciers, frozen ground, the hydrological system, and alpine
vegetation have changed over the past decades years. Climatic causes of these variations have been analyzed using mean monthly
air temperature and monthly precipitation between 1956 and 2000, and monthly evaporation from φ20 evaporation pans between
1961 and 1996. In the source region of the Yangtze River, lower temperature and plentiful precipitation during the 1960s and
continuing into the early 1980s triggered a glacier advance that culminated in the early 1990s, while a robust temperature
increase and precipitation decrease since 1986 has forced glaciers to retreat rapidly since 1995. Permafrost degradation is
another consequence of the climatic warming. The variations in the hydrological system and alpine vegetation are controlled
mainly by the climate during the warm season. Warmer and drier summer climate is the major cause of a degradation of the vegetation,
desiccation of the high-cold marshland, a decrease in the areas and numbers of lakes and rivers in the middle and north source
regions of the Yangtze and Yellow Rivers, and a reduction in surface runoff in the source region of the Yangtze River for
the last 20 years. The causes of eco-environmental change in Dari area, near the outlet from the source area of the Yellow
River, are different from those elsewhere in the study area. A noticeable reduction in runoff in the source region of the
Yellow River and degradation of alpine vegetation in Dari area are closely related to the permafrost degradation resulting
from climate warming. 相似文献
5.
长江源区高寒生态与气候变化对河流径流过程的影响分析 总被引：24，自引：5，他引：19
近40 a来长江源区气候变化剧烈,是青藏高原增温最为显著的地区之一,高寒生态系统与冻土环境不断退化.采用多因素逐次甄别方法与半经验理论方法相结合,基于多年冻土的不同植被覆盖降水-径流观测场观测试验结果,分析了长江源区气候-植被-冻土耦合系统中各要素变化对河川径流的不同影响.结果表明:近40 a来长江源区河川径流呈持续递减趋势,年均径流量减少了15.2%,频率>20%的径流量均显著减少,而>550 m3·s-1的稀遇洪水流量发生频率增加;气候变化与高寒草甸覆盖变化对源区径流变化的影响较大,分别占5.8%和5.5%;气候与植被覆盖变化对径流的显著影响是与冻土耦合作用的结果,但冻土环境与冰川变化对径流的贡献尚不能准确评价.高寒沼泽湿地和高寒草甸生态系统对于源区河川径流的形成与稳定起到关键作用,这两类生态系统的显著退化是驱动河川径流过程中变差增大、降水-径流系数减少以及洪水频率增加的主要原因.保护源区高寒草甸与独特的高寒湿地生态,对于维护源区水涵养功能和流域水安全意义重大. 相似文献
6.
Some rainfall-related thresholds for erosion and sediment yield in the upper Yangtze River basin 总被引：1，自引：0，他引：1
Jiongxin Xu 《Environmental Geology》2009,56(6):1183-1192
This study examines rainfall thresholds for erosion and sediment yield in the upper Yangtze River basin. Sediment reduction
effects of soil conservation measures depend on the magnitudes of rainstorm. When the latter is less than a critical threshold,
sediment reduction effects of soil conservation measures are positive; when this magnitude is exceeded, the effect is negative.
An analysis based on data from the Jialingjiang River shows that the sediment reduction by soil conservation measures increased
with annual precipitation to a peak, and then decreased to a negative value. The annual precipitation at the peak and zero
values of sediment reduction are 970 and 1,180 mm, respectively, which can be regarded as two thresholds. Annual precipitation
at the zero-value of sediment reduction has a return period of 25 years. In general, the design standard of soil conservation
works in China is related with rainstorms with return periods of 10–20 years. When the magnitude of rainstorm exceeds this,
the soil conservation works may be partly or totally destroyed by rainstorms, and the previously trapped sediment may be released,
resulting in a sharp increase in sediment yield. It was also found in the lower Jinshajiang River that when annual precipitation
exceeds 1,050 mm or high-flow season precipitation exceeds 850 mm, the annual sediment yield increased sharply. These can
also be regarded as key rainfall thresholds for erosion and sediment yields. When precipitation is less than the two thresholds,
dominant erosion types are sheet, rill and gully erosions. When precipitation crosses the two thresholds, debris flows may
occur more frequently. As a result, the previously stored loose sediment is released and sediment yield increases sharply. 相似文献
7.
渭河上游典型小流域水文特征差异性分析 总被引：3，自引：2，他引：1
根据渭河流域两个典型小流域的实测水文和气象资料,分析了不同气候和下垫面条件的流域水文特征及其差异性.结果表明:清源河和牛谷河流域的年平均气温呈上升趋势,降水、径流、泥沙、降水径流系数均呈减少趋势;两个流域的降水、径流和泥沙历年变化不一致,1998-2013年清源河流域降水量相对牛谷河流域减少了8.6%,1993-2013年牛谷河的径流相对减少了21.4%,2000-2013年清源河的泥沙相对减少了24.0%;两个流域的面积、河长、海拔、植被覆盖率等流域特征值相对差在-29.4%~-4.5%之间,气温、降水等气候特征值相对差在-27.4%~16.7%之间,而径流特征值相差较大,相对差在-90.2%~-84.7%之间,泥沙特征差异性更大,相对差在292%~347%之间.对气候、下垫面和人类活动对水文要素的影响进行了研究,受人类活动的影响,清源河流域1996-2013年年径流减少11.6%,牛谷河流域1993-2006年年径流减少25.9%,2007-2013年再减少10.5%,研究人类活动的调水减沙效应,对流域综合治理、生态环境建设具有一定的指导意义.同时,充分利用不同小流域实测水文气象数据,分析水文气象要素的变化规律,可以为分布式水文模型研究和中小河流洪水预警预报提供重要依据. 相似文献
8.
黄河数字流域模型是“数字黄河”的重要组成部分,在数字流域模型框架下,以坡面为基本单元,建立了包括植被截留、融雪、地表蓄滞、表层土蓄滞、中层土蓄滞和深层土蓄滞共6层的产流模型.模型在垂向上考虑3层出流:地表超渗产流、表层土侧向渗流和中层土侧向渗流,既反映当前的降水过程,又体现前期降水过程和土壤前期含水量的影响,比较适合黄河流域的产流特点.在坡面产流的基础上,还给出了坡面单元侵蚀产沙公式,用于建立流域产沙数学模型.应用建立的模型,给出了3个计算实例:黄河全流域水量计算、小花区间汛期洪水模拟和多沙粗沙区产沙计算.实践表明:建立的模型基本具备了在黄河全流域进行降雨-径流模拟、侵蚀产沙计算的功能,辅以降雨预报模块则可进行洪水预报. 相似文献
9.
应用祖厉河流域1956~2016年实测水文资料,采用水文统计法、差积曲线法、突变检验法等方法,分析了流域水沙时空分布规律及水沙关系。结果表明:祖厉河流域年降水量、年径流深从上游向下游减小;支流关川河巉口以上年输沙模数相对较小,中游会宁-郭城驿最大。4个代表站历年降水量、径流量、输沙量均呈显著减少趋势,降水量年内分配主要集中在5~9月,径流量和输沙量主要集中在6~9月;水沙变化的突变年份为1999年,基准期1956~1999到措施期2000~2016年多年平均年径流量和输沙量分别减少了39.6%、72.9%。流域降水量年均减少0.53~1.23mm,气温年均升高0.029~0.042℃/a,植被覆盖度年均增加0.85%/a,降水减少、水土保持措施面积增加和植被覆盖度大幅提高是流域水沙持续减少的主要原因。 相似文献
10.
长江-黄河源寒区径流时空变化特征对比 总被引：40，自引：8，他引：32
长江源区比黄河源区寒冷而干燥, 年径流量仅为黄河源区的60%, 径流年内分配较黄河源区均匀性差, 丰水年与枯水年比例基本相当, 而黄河源区枯水年占较大优势. 近40 a来长江源区径流量总体上呈明显的递减趋势, 黄河源区径流量则呈现略微增长趋势. 长江源区径流量以8～9 a的周期变化较为显著, 黄河源区径流量则以7～8 a周期比较显著. 对寒区径流变化的主要影响因子分析表明, 长江源区温度因子对径流年际变化影响大于黄河源区, 而降水因子影响相对较小, 长江源区寒区水文环境对径流影响较大是造成长江、黄河源区径流差异形成的主要原因. 相似文献
11.
以流域时空分布理论框架为基础,分析嫩江流域径流时空演化规律,并着重从地形地貌影响因素方面进行归因分析。采用1955-2003年49 a的降水资料和1955-1973年19 a的径流资料,通过对代表性水文站自上游至下游（空间上）径流、地表径流和地下径流的年内与年际（时间上）演变规律进行分析。结果表明：1）嫩江流域降水年内变化及年际变化过程基本一致,可以忽略降水时空分布对径流时空演化规律的影响。2）从径流年内演化规律上可以判定上下游水源组合的差异性：上游以地表径流为主,在春季来源于融雪,汛期来源于大气降水,枯水季节来源于地下水补给;下游全年以地下径流为主。3）由于坡度和水文地质条件作用,上游更容易产流,下游受下垫面调蓄作用更强,不易产流;因此,从径流年际演化规律上可以判定径流产量自上游至下游逐渐减小。 相似文献
12.
黄河上游春季径流的特征 总被引：4，自引：10，他引：4
本文指出,在唐乃亥以上的黄河上游干流融雪径流是3月下旬至6月上旬期间径流量的主要成份,所占比例在40％以上。据此,对NOAA/TIROS气象卫星云图的积雪遥感信息应用于黄河上游春季融雪径流预报进行了尝试。根据1987年龙羊峡水库实测资料验证,预报精度在80％以上,基本符合业务预报要求。 相似文献
13.
Spatial and temporal variations in alpine vegetation cover have been analyzed between 1982 and 2001 in the source regions of the Yangtze and Yellow Rivers on the Tibetan Plateau. The analysis was done using a calibrated-NDVI (Normalized Difference Vegetative Index) temporal series from NOAA-AVHRR images. The spatial and temporal resolutions of images are 8 km and 10 days, respectively. In general, there was no significant trend in alpine vegetation over this time period, although it continued to degrade severely in certain local areas around Zhaling and Eling Lakes, in areas north of these lakes, along the northern foot of Bayankala Mountain in the headwaters of the Yellow River, in small areas in the Geladandong region, in a few places between TuoTuohe and WuDaoliang, and in the QuMalai and Zhiduo belts in the headwaters of the Yangtze River. Degradation behaves as vegetation coverage reduced, soil was uncovered in local areas, and over-ground biomass decreased in grassland. The extent of degradation ranges from 0 to 20%. Areas of 3×3 pixels centered on Wudaoliang, TuoTuohe, QuMalai, MaDuo, and DaRi meteorological stations were selected for statistical analysis. The authors obtained simple correlations between air temperature, precipitation, ground temperature and NDVI in these areas and constructed multivariate statistical models, including and excluding the effect of ground temperature. The results show that vegetation cover is sensitive to variations in temperature, and especially in the ground temperature at depths of ∼40 cm. Permafrost is distributed widely in the study area. The resulting freezing and thawing are related to ground temperature change, and also affect the soil moisture content. Thus, degradation of permafrost directly influences alpine vegetation growth in the study area. 相似文献
14.
Evolutionary trend of water cycle in Beichuan River Basin of China under the influence of vegetation restoration 
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下载免费PDF全文 To understand the influence of vegetation restoration on the water cycle in semiarid areas, the effects of vegetation restoration on evolution of the key elements of water cycle were clarified by analyzing the evolutionary trend of atmospheric precipitation, ecological consumption water, and surface runoff on a river basin scale on the basis of analytical results of the changes in vegetation coverage and the long-term meteorological and hydrological monitoring data of Beichuan River Basin. The results show that the vegetation cover in the Beichuan River basin has rapidly increased in the hilly and mountainous areas since the 1980s, especially from 2000 to 2019, with the maximum and average vegetation cover rates increased by 14.98% and 52.2%, respectively. During 1956-2016, the annual precipitation in the basin remained relatively stable; the annual surface runoff slightly declined, with an average attenuation rate of 20 million m~3/10 a. The main reason for the runoff decline is the increase in ecological water induced by the vegetation restoration, which has changed the spatial-temporal distribution of the water from atmospheric precipitation in the basin. Spatially, more precipitation was converted into ecological water. As a result, the remnant runoff supplied to the lower reaches reduced accordingly. Temporally, more precipitation participated in the soil water-groundwater cycle, thus prolonging the outward drainage period of the precipitation. Moreover, the large-scale vegetation restoration induced a significant decrease in the surface wind speed, evaporation from water surface and drought index. As a result, a virtuously mutual feedback relationship was formed between the vegetation and meteorological elements. Therefore, vegetation restoration is of great significance for the improvement in the water conservation capacity and semiarid climate conditions in the Beichuan River basin. 相似文献
15.
长江源区小冬克玛底冰川区积雪消融特征及对气候的响应 总被引：6，自引：3，他引：3
2005年使用花杆法在小冬克玛底冰川上进行了两轮积雪融化观测,结果显示:6月中、下旬,冰川区积雪消融基本与气温同步变化,但到7月上旬积雪消融发生了变化:其融化时间提前了2 h,在12:00融化量就达到一定高度;融化量大,日平均融化量较6月中下旬大0.71 mm水当量;最大积雪融化量出现时间滞后于气温最高时间约2 h,于18:00达到最大值.雪坑雪层剖面真实记录了积雪积累与融化过程中的雪层变化.积雪融化除受温度影响之外,还与风速等其它因素有密切关系.温度越高,融化量越大;风速与积雪融化量的关系相对复杂.积雪融化量只与1.5 m高度风速有关.在2h尺度上,近地面风速大,积雪融化量也大;在日尺度上,风速与积雪融化量的关系较好,但在两个观测时段表现出不同的相关关系.研究区积雪量很少,受昼夜气温变化与下垫面状况的影响,积雪融水几乎不产生径流,对河川径流的影响程度极小. 相似文献
16.
以黄河流域的降水、实测径流量、天然径流量、净引水量以及上中游流域的水土保持措施面积等资料为基础,运用经验统计分析法,研究了近50年来黄河入海径流通量的变化及其与降水和人类活动的关系。结果表明,不同的径流来源区降水的变化对入海径流通量的影响是不同的。引水所形成的侧支循环强度的急剧增大,使入海径流通量大幅度下降。上中游大规模水土保持生效后,这一地区的天然年径流有所减少,也导致入海径流通量的减少,入海径流通量与历年梯田、造林、种草面积之间具有一定的负相关。以入海径流通量作为因变量,以净引水量、流域年降水量和上中游梯田、林草面积作为自变量,建立了多元回归方程。 相似文献
17.
18.
为研究潮汐河道不同区段在流域来沙减少条件下的冲淤响应机制,以长江澄通河段为例,根据水动力特性将其划分为江阴—天生港和天生港—徐六泾两段,结合1950—2014年的水沙资料及2005—2014年的地形资料,比较两段冲淤对流域减沙的响应差异。结果表明:上游江阴—天生港段对流域减沙敏感,较快地由淤积转为冲刷;下游天生港—徐六泾段1998—2004年期间受洪季平均径流流量减小、潮汐顶托作用相对增大的影响,冲刷速率为减小趋势,2004年以后受洪季平均径流流量增大、潮汐顶托作用相对减小及流域来沙持续减少的共同影响,冲刷速率为增大趋势。使得潮汐动力对天生港—徐六泾段由促淤变为促冲的临界洪季平均径流流量为36 000 m3/s,该径流流量也是使得潮汐顶托作用在江阴—天生港段由不显著变为显著的临界流量。目前,流域减沙已加剧澄通河段整体的冲刷。 相似文献
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黄河流域近期水沙变化及其趋势预测 总被引：9，自引：0，他引：9
针对黄河水沙近期发生显著变化的现象,利用黄河上中游干支流水文泥沙定位观测资料,综合"水文法"、"水保法"和数学模拟等多种方法,对黄河流域1997-2006年水沙变化情势进行了评估,分析了水沙变化机制,并预测了未来的变化趋势。分析表明,与多年平均相比,黄河河源区径流量年均减少43.90亿m3,其中降雨等自然因素的影响量占92.26%,人类活动影响量占7.74%;与1970年前相比,黄河实测径流量年均减少112.1亿m3,其中水利水土保持综合治理等人类活动作用占76.50%,因降雨影响占23.50%;实测输沙量较1970年以前年均减少11.80亿t,其中水利水土保持综合治理等人类活动的作用为49.75%,降雨的影响为50.25%;人类活动与降雨变化对水沙变化的影响差异较大,就黄河中游地区总体而言,人类活动的减水作用远大于降雨的影响,人类活动的减沙作用与降雨影响基本相当,不宜笼统说黄河中游水沙变化主要是人类活动所致或主要是降雨变化所致; 2050年以前黄河来水来沙量总体呈平偏枯趋势,但不排除个别年份或短时段仍会发生丰水丰沙的可能性。 相似文献
20.
黄河泥沙未来变化趋势关系到新时期治黄策略制定，科学认知入黄沙量变化特征，特别是一些典型或极端情况下的沙量变化原因，对于科学研判黄河泥沙未来情势具有重要指导意义。本文在分析百年黄河沙量演变特征基础上，重点解析了2013年和2018年典型"大沙"年份以及2017年典型"极端降雨"年份潼关沙量波动变化原因。结果表明：1919—2018年百年尺度上黄河潼关站输沙量呈"台阶式"减少特征且减少趋势极显著（P<0.001），尤其2000年以后年均输沙量降至2.44亿t左右；随着黄土高原下垫面土壤侵蚀环境大幅改善，黄河上游相似来水年头道拐—潼关区间流域输沙量减少82%，相似极端降雨情景下流域次洪输沙量平均减少50%~85%，2017极端降雨年并未导致大沙年出现，水土保持生态建设成果在减少入黄泥沙方面发挥了关键作用；2013年和2018年典型"大沙"年潼关站泥沙来源解析表明，河道淤积泥沙冲刷和水库排沙成为新时期黄河潼关站沙量波动变化的主要影响因素。 相似文献