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1.
三峡工程对鄱阳湖冲淤的影响和预测 总被引：2，自引：3，他引：2
泥沙淤积是制约湖泊功能的重要因素。三峡工程运行后增减下泄流量,将使鄱阳湖的泥沙交换和淤积作用发生变化。本文根据鄱阳湖的沉积特点,利用典型年的水文过程对库区增减下泄流量时的冲淤变化进行了预测,指出直接的影响不大,但洲滩发展和束狭入江断面的负效应须有所警惕。 相似文献
2.
为了研究洪泽湖水沙特性、变化趋势与冲淤时空分布规律,运用累积距平法、Mann-Kendall趋势与突变检验以及R/S分析法等方法,分析了洪泽湖19502016年的水沙特征;采用地理信息技术,基于1992年和2016年实测地形,对湖区泥沙冲淤空间分布进行了定量计算与分析.结果表明,入湖径流量无明显增加或减少的趋势,输沙量和含沙量呈明显减小趋势,1990年以后含沙量基本稳定在0.2 kg/m^3以下;淮河干流(包括池河)入湖水量和沙量约占入湖总量的89.6%,三河闸出湖水沙占总出湖量的60%.淮干入湖口和溧河洼为主要淤积区域,淤积量分别为2300×10^4和1900×10^4 m^3,平均淤积厚度分别为0.35和0.25 m;其他区域自然冲淤基本平衡.上游水库和河道闸坝的拦沙作用、农业种植结构变化和水土保持、大规模人工采砂等是入湖沙量减少的主要影响因素;湖区水动力特性是泥沙自然淤积主导因素,而湖区库容变化的主因则是人工采砂、围湖造田和围网养殖,且人类活动的影响远大于自然冲淤. 相似文献
3.
洞庭湖近几十年来湖盆变化及冲淤特征 总被引：19，自引：5，他引：19
洞庭湖是我国著名的五大淡水湖泊之一,位于长江中游荆江段南岸,湖南省境内.历史时期,曾经是我国第一大淡水湖,直至新中国成立初期,湖泊面积仍然有4350km2,居我国淡水湖泊之首位.但由于洞庭湖承纳“四水”,吞吐长江,长江大量水沙涌入洞庭湖,造成了湖盆迅速淤高,加之由此诱发的人类大规模地湖泊垦殖活动,湖泊急剧萎缩.目前,洞庭湖已退居鄱阳湖之后,为我国第二大淡水湖泊.湖泊的严重泥沙淤积,已经造成了湖泊调蓄长江中游洪水功能的严重衰退,不但危及湖南省的防洪的安全,而且危及长江中下游地区的防洪安全,研究洞庭湖的湖盆冲淤演变具有重要意义.本文根据1974、1988和1998年洞庭湖125000水下地形资料,并针对洞庭湖具有显著上下游水位落差的实际,分不同高程和不同水位情况下,分析洞庭湖湖泊面积和容积演变特征,探讨洞庭湖近几十年来的湖盆变化及冲淤规律,试图揭示洞庭湖湖泊调蓄能力的变化过程. 相似文献
4.
鄱阳湖流域大型湖库水生生态环境变化及驱动力分析——以柘林湖为例 总被引：3，自引：2，他引：1
鄱阳湖流域内湖库资源众多,柘林湖作为鄱阳湖最大的入湖湖库,是鄱阳湖流域内最大的调节湖库,对鄱阳湖入湖径流有一定的影响,在鄱阳湖的入湖流量中占重要地位.本文以鄱阳湖流域内纳入水质良好湖泊的柘林湖为例,通过对柘林湖的形成及湖泊水系生态环境演变进行探讨,分析近30年来该湖水生生态环境的变化及其关键驱动力因子.综合研究表明:柘林湖水生生物多样性有下降趋势,水质有先变差后改善的趋势,其变化的驱动力主要是流域内人口数量增加、城镇化工业化进程加快、入湖污染负荷逐年增长、滨湖区生态安全屏障受人为破坏以及资源开发不合理等.只有处理好"人湖"和谐、"三次飞跃"和"四大转变",并采取科学合理的措施进行集成研究和综合治理,才能行之有效地改善柘林湖水生生态环境,并发挥其应有的生态效应,从而保障鄱阳湖入湖"一湖清水". 相似文献
5.
三峡工程运行后长江中下游河道洲滩普遍冲刷萎缩,航道条件极不稳定.为探究影响洲滩演变的主控因素,采用近期水文、泥沙和地形观测资料,以下荆江铁铺水道广兴洲边滩为例,分析了边界条件、水沙过程及整治工程等因素对洲滩调整特征的影响程度.结果表明:洲滩组成中的细沙(0.125 mm15000 m3/s)有一定关系,其持续时间越长,一般表现为滩体面积越小;汛期悬移质分组沙输移过程中,细沙的大幅减少导致边滩萎缩明显,其影响程度比漫滩流量更大.滩体冲淤变形特征与前3年漫滩流量下平均水流冲刷强度的相关性最好.守护工程实施后,漫滩流量下平均水流冲刷强度仍然较大,但滩体后退趋势得以抑制且小幅淤积,工程效果得以充分发挥. 相似文献
6.
近浅海水下地形演变事关堤岸、航运及港口安全,一直是地理学和工程学界研究的热点.利用多波束测深系统对长江大通至徐六泾河段水下地形进行了统计,结合历史资料分析了该河段1998~2013年的冲淤格局.结果表明:(1)1998~2013年大通至徐六泾河段总体呈"冲-淤-冲"特征.其中,上段冲刷700×10~6m~3;中段淤积204×10~6m~3;下段冲刷602×106m3.(2)沙波是研究河段最常见的床面地形,约占整个河段的64.3%;其次为各类冲刷地形(约27.6%);平床地形约占6.6%.(3)人类活动可直接影响水下地形形态的自然发育,如于沙波表面形成直径20~35m,深3~5m的采砂坑.分析认为三峡大坝的修建导致了流域来沙量急剧下降,是研究河段整体上呈冲刷趋势(净冲刷约468×10~6m~3)的主要原因,而其他人类活动,如岸线利用、航道整治束窄了河道,制约了河流的横向摆动,加剧了受冲岸段的岸坡冲刷. 相似文献
7.
1952-2011年鄱阳湖枯水变化分析 总被引：17，自引：11，他引：6
利用鄱阳湖区1952-2011年水文监测资料,分析鄱阳湖近60 a来枯水特征及其变化规律;从流域降水、五河来水、长江上中游来水、湖盆形态等方面的变化,探讨鄱阳湖枯水变化原因.结果表明,进入21世纪后的近11 a鄱阳湖枯水程度显著加剧,尤其是近5 a来最低水位不断被刷新;造成鄱阳湖枯水变化的最主要原因是流域降水和五河来水的相应变化,其次是长江上中游来水变化,湖盆形态变化对于近10 a来枯水加剧起到了推波助澜的作用;三峡大坝蓄水以后,长江上中游来水变化对鄱阳湖枯水变化的控制作用呈现逐渐加强态势. 相似文献
8.
以往关于三门峡水库的研究多关注库区年际间的冲淤变化，而对汛期和非汛期库区冲淤分布研究较少。本文基于三门峡水库蓄清排浑运用以来1974 2018年实测水沙、断面及冲淤数据，研究汛期和非汛期库区冲淤重心的迁移、冲淤速率及其对潼关高程的影响。结果表明，蓄清排浑运用以来库区河道基本遵循汛期冲刷、非汛期淤积的演变规律。分别定义汛期最大冲刷速率和非汛期最大淤积速率发生的相邻两断面间的子河段为冲刷重心和淤积重心，汛期冲刷重心与非汛期淤积重心出现的位置基本对应，1974 2010年冲淤重心由距坝约90 km逐渐向坝前移动，平均下移速率约1～2km/a;2010年后冲淤重心逐渐上移，2017年位于坝上游约60～70 km，但冲淤强度明显减弱。淤积重心的位置主要受水库回水长度影响，冲刷重心主要与汛期水流能量相关，淤积重心位置迁移滞后于影响因子的变化约5年，而冲刷重心滞后时间约2年。潼关高程与潼关至太安段（潼太段）比降呈反比关系，比降越大，潼关高程越低，而当冲刷重心迁移至潼太段并影响其下段时，潼太段比降增大，利于潼关高程降低。1985年后回水范围和冲淤重心均位于潼关以下，潼关高程受冲淤重心影响较小。 相似文献
9.
气候变化和人类活动对鄱阳湖流域赣江径流影响的定量分析 总被引：5，自引：2，他引：3
气候变化和人类活动对流域径流影响的定量研究是当前研究的热点,赣江作为鄱阳湖流域最大的子流域,径流变化对鄱阳湖湿地水生态系统具有重要的影响.利用Mann-Kendall突变检验分析了赣江流域径流1955—2010年间演变趋势,再分别应用统计方法和IHACRES集总式模型分析气候要素和人类活动对径流的影响.研究表明IHACRES能够较好地模拟赣江流域径流,适用于中亚热带湿润季风气候区.Mann-Kendall突变检验表明赣江流域径流在1979年发生突变,可划分为1955—1979年和1980—2010年两个时段.降水是影响赣江流域径流年际变化的主要因素,而土地利用等人类活动的影响并不明显.水库建设显著影响赣江径流的季节分配,1980—2010年间人类活动影响更加显著,其中45%的年份秋季径流增加50%以上,26%的年份秋季径流增加超过100%,其中1989年的秋季径流增加幅度达到320%. 相似文献
10.
基于2010年鄱阳湖最新地形,构建精细的鄱阳湖二维水动力数学模型,相同网格下构建1998年地形,分别模拟不同地形条件下2006年枯水年水位、流量时空分布,分析地形变化对水位、流量的影响,阐释地形影响的时空差异.结果表明:相比1998年,2010年地形由于北部入江通道的下切,相同的2006年水文条件下,水位普遍降低;水位越低,上下游水面坡降越大,受地形影响越明显;低水位最大降幅1~2 m,而高水位最大不超过0.4 m,分别对应湖口9 m以下、15 m以上水位;地形对水位的影响程度都昌星子棠荫康山;都昌至湖口段水头差降低了2 m,水面坡度变缓,棠荫至都昌段水面坡度变陡,康山至湖口水头差基本不变;全年出湖总流量增加了6%;地形变化影响最显著为河道区,影响范围可波及大部分湖区,局部地形的变化使得子湖水面积也存在一定差异.本研究首次基于水动力模拟量化了鄱阳湖地形变化对水位的影响程度和范围,结果可为水资源管理、江湖关系演变分析、湿地生态环境保护等提供科学参考. 相似文献
11.
The sediment delivery ratio in a small catchment in the black soil region of Northeast China 总被引：1，自引：0，他引：1
The black soil region of northeast China,which covers the Provinces of Heilongjiang,Jilin and the Inner Mongolia autonomous region with black soil,chernozem and meadow soil,has experienced soil erosion since intense agricultural reclamation began approximately 100 years ago.However,the sediment delivery ratio,defined as the fraction of gross erosion that is transported from a given area in a given time interval,is still unclear.In this study,we calculated the delivery ratio and analysed changes in erosive processes within Hebei catchment from 1977 to 2007 based on an analysis of sediments of the Liudui reservoir.The original vegetation layer clearly identified the bottom of the reservoir when it was constructed in 1977;thus,the reservoir sediments could be precisely dated.The delivery ratio,calculated by comparing the sediment deposition in the reservoir with the total soil erosion in the upstream catchment,was found to be exponentially correlated（r2 = 0.95,P < 0.01） with decreasing grain size,except for the fraction <0.002 mm.The delivery ratio for the clays（<0.002 mm） was low,averaging 0.10 during the study period, which indicated partial removal of clays from the reservoir.The changes in the reservoir deposition rate reflected the temporal changes in the erosion processes.The exceptionally high rainfall in 1998 was confirmed by the distributions of 137Cs,210Pb,and the grain-size of the sediments.Beginning from the position of the original grass layer,we defined three periods from 1977 to 2007 based on deposition rates:2.40 cm year-1 from 1977 to 1997,5.60 cm year-1 in 1998 due to unusually high rainfall,and 1.55 cm year-1 from 1999 to 2007.The overall average deposition rate for the entire period was 2.26 cm year-1.Precipitation was found to be the main factor affecting the soil erosion of the study area. 相似文献
12.
研究了鄱阳湖流域在1955-2002年间的径流系数的变化,重点分析了它与水循环的两个基本要素:降水量和蒸发量的关系,同时对其原因进行了初步的探讨.经分析,在鄱阳湖流域中,径流系数较大的是饶河流域和信江流域,较小的是抚河流域;在年内变化上,4-6月为五河流域径流系数比较大的月份,这与鄱阳湖流域降水集中期相对应.在空间上,4-6月仍然以饶河流域和信江流域相对较大,而抚河流域较小,特别是8月份的径流系数远小于其他四河;年代际变化上,1990s径流系数增加较为显著.尽管鄱阳湖流域的径流系数除了受气候因子的影响外,还受到水土流失和地形等因素的影响,但是降水量的增加,特别是暴雨频率的增加仍然是其主要影响因素,蒸发量的减小对径流系数的增加也有一定程度的影响.径流系数与气温并无明显的线性相关关系. 相似文献
13.
Abstract Poyang Lake is the largest freshwater lake in China, and plays a major role in flood mitigation, restoration and conservation of the ecological environment in the middle Yangtze River basin. Sediment load and streamflow variations in Poyang Lake basin are important for the scouring and deposition changes of this lake. However, these hydrological processes are heavily influenced by human activities, such as construction of water reservoirs, and land-use/land cover changes. By thorough analysis of long series of sediment and streamflow obtained from five major hydrological stations, we systematically investigated the spatial and temporal patterns of these hydrological processes and the hydrological responses to human activities using the Mann-Kendall trend test, the double cumulative mass curve and the linear regression method. The results show: (1) no significant change in streamflow followed by an increasing tendency after the 1990s that turns to be decreasing about 2000; and (2) a sharp increase of sediment load during the late 1960s and 1970s triggered by extensive deforestation (during the “Cultural Revolution” in China) followed by a tendency to decrease after the early 1980s. Construction of water reservoirs has greatly reduced the sediment load of the Poyang Lake basin, and this is particularly the case in the Ganjiang River, where the sediment load changes may be attributed to the trapping effects of the Wan'an Reservoir, the largest water reservoir within the Poyang Lake basin. There is no evidence to corroborate the influence of water reservoirs on the streamflow variations. It seems that the streamflow variations are subject mainly to precipitation changes, but this requires further analysis. The current study may be of scientific and practical benefit in the conservation and restoration of Poyang Lake, as a kind of wetland, and also in flood mitigation in the middle Yangtze River basin that is under the influence of human activities. Citation Zhang, Q., Sun, P., Jiang, T. & Chen, X.-H. (2011) Spatio-temporal patterns of hydrological processes and their hydrological responses to human activities in the Poyang Lake basin, China. Hydrol. Sci. J. 56(2), 305–318. 相似文献
14.
鄱阳湖区域极端降水异常的特征及成因 总被引：3，自引：1，他引：2
鄱阳湖区域4-7月极端降水总量存在显著的2-4年周期变化,且鄱阳湖4-7月极端降水总量的变率存在比较显著的增加趋势.1998年6月鄱阳湖地区极端降水总量异常偏多,而2001年6月异常偏少,仅为1998年的13.5%左右.通过分析大气环流场、水汽输送等方面的差异,发现1998年6月500hPa高度场上乌拉尔山高脊和鄂霍次... 相似文献
15.
Hydrogeomorphic processes influencing alluvial gully erosion were evaluated at multiple spatial and temporal scales across the Mitchell River fluvial megafan in tropical Queensland, Australia. Longitudinal changes in floodplain inundation were quantified using river gauge data, local stage recorders and HEC‐RAS modelling based on LiDAR topographic data. Intra‐ and interannual gully scarp retreat rates were measured using daily time‐lapse photographs and annual GPS surveys. Erosion was analysed in response to different water sources and associated erosion processes across the floodplain perirheic zone, including direct rainfall, infiltration‐excess runoff, soil‐water seepage, river backwater and overbank flood inundation. The frequency of river flood inundation of alluvial gullies changed longitudinally according to river incision and confinement. Near the top of the megafan, flood water was contained within the macrochannel up to the 100‐year recurrence interval, but river backwater still partially inundated adjacent gullies eroding into Pleistocene alluvium. In downstream Holocene floodplains, inundation of alluvial gullies occurred beyond the 2‐ to 5‐year recurrence interval and contributed significantly to total annual erosion. However, most gully scarp retreat at all sites was driven by direct rainfall and infiltration‐excess runoff, with the 24‐h rainfall total being the most predictive variable. The remaining variability can be explained by seasonal vegetative conditions, complex cycles of soil wetting and drying, tension crack development, near‐surface pore‐water pressure, soil block undermining from spalling and overland flow, and soil property heterogeneity. Implications for grazing management impacts on soil surface and perennial grass conditions include effects on direct rainfall erosion, water infiltration, runoff volume, water concentration along tracks, and the resistance of highly dispersible soils to gully initiation or propagation under intense tropical rainfall. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
16.
EXTRACTING FEATURES OF ALLUVIAL FAN AND DISCUSSING LANDFORMS EVOLUTION BASED ON HIGH-RESOLUTION TOPOGRAPHY DATA: TAKING ALLUVIAL FAN OF LAOHUSHAN ALONG HAIYUAN FAULT ZONE AS AN INSTANCE 
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下载免费PDF全文 HAN Long-fei ZENG Jing YUAN Zhao-de SHAO Yan-xiu WANG Wei YAO Wen-qian WANG Peng LIANG Ou-bo XU Xin-yue 《地震地质》2019,41(2):251-265
Range-front alluvial fan deposition in arid and semiarid environments records vast amounts of climatic and tectonic information. Differentiating and characterizing alluvial fan morphology is an important part in Quaternary alluvial fan research. Traditional method such as field observations is a most important part of deciphering and mapping the alluvial fan. Large-scale automatically mapping of alluvial fan stratigraphy before traditional field observations could provide guidance for mapping alluvial fan morphology, thus improving subsequent field work efficiency. In this research, high-resolution topographic data were used to quantify relief and roughness of alluvial fan within the Laohushan. These data suggest that mean surface roughness plotted against the size of the moving window is characterized by an initial increase in surface roughness with increased window size, but it shows no longer increase as a function of windows size. These data also suggest that alluvial fans in this study site smooth out with time until a threshold is crossed where roughness increases at greater wavelength with age as a result of surface runoff and headward tributary incision into the oldest surfaces which suggests the evolution process of alluvial fan.
Researchers usually differentiate alluvial morphology by mapping characteristics of fan surface in the field by describing surface clast size, rock varnish accumulation, and desert pavement development and analysis of aerial photographs or satellite imagery. Recently, the emergence of high-resolution topographic data has renewed interest in the quantitative characterization of alluvial and colluvium landforms. Surface morphology that fan surface initially tends to become smoother with increasing age due to the formation of desert pavement and the degradation of bar-and-swale topography and subsequently, landforms become more dissected due to tectonics and climatic change induced increased erosion and channelization of the surface with time is widely used to distinguish alluvial fan types. Those characteristics would reflect various kinds of morphology metrics extracted from high-resolution topographic data. In the arid and semiarid regions of northwestern China, plenty of alluvial fans are preserved completely for lack of artificial reforming, and there exists sparse surface vegetation. In the meantime, range-front alluvial fan displaced by a number of active faults formed a series of dislocated landforms with different offsets which is a major reference mark in fault activity research. In this research, six map units(Qf6-Qf1), youngest to oldest, were observed in the study area by mapping performed by identifying geomorphic features in the field that are spatially discernible using hill-shade and digital orthophoto map. Alluvial fan relief and roughness were computed across multiple observation scales(2m×2m to 100m×100m)based on the topographic parameters of altitude difference and standard deviation of slope, curvature and aspect.
In this research, mean relief keeps increasing with increased window size while mean surface roughness is characterized by a rapid increase over wavelengths of 6~15m, representing the typical length scale of bar-and-swale topography. At longer wavelengths, surface roughness values increase by only minor amounts, suggesting the topographic saturation length is 6~15m for those fan surfaces in which saturation length of standard deviation of curvature is less than 8m. Box and whisker plot of surface roughness averaged over 8m2 for each alluvial fan unit in the study area suggests that the pattern of surfaces smoothing out with age and then starting to become rougher again as age increases further beyond Qf4 or Qf3 unit. The younger alluvial fan is characterized by prominent bar-and-swale while the older alluvial fan is characterized by tributaries headward incision. Cumulative frequency distributions of relief and surface roughness in Figure 8 are determined in an 8m by 8m moving window for the comparison of six alluvial fan units in the northeast piedmont of Laohushan. From these distributions we know that Qf6 and Qf1 reflect the prominent relief which is related to bar-and-swale and tributaries headward incision respectively, while Qf4 and Qf3 reflect the moderate relief which is related to subdued topography.
Surface roughness, in addition to facilitating the characterization of individual fan units, lends insight to alluvial landform development. We summarize an alluvial landform evolutionary scheme which evolves four stages depending on characteristics of alluvial fan morphology development and features of relief and roughness. The initial stage in this study site is defined as the active alluvial fan channels with bars of coarse cobbles and boulders and swales consisting of finer-grained pebbles and sand which could be reflected by high mean relief and mean roughness values. As time goes, bar-and-swale topography is still present, but an immature pavement, composed of finer grained clasts, has started to form. In the third stage, the bar-and-swale topography on the fan surface is subdued, yet still observable, with clasts ranging from pebbles to cobbles in size and there exists obvious headward tributary incision. Eventually, tributary channels form from erosion by surface runoff. Headward incision of these tributaries wears down the steep walls of channels that are incised through the stable, planar surface, transforming the oldest alluvial landforms into convex hillslopes, leaving only small remnants of the planar surface intact. Those evolutionary character suggests that alluvial fans in this area smooth out with time, however, relief or roughness would be translated to increase at greater wavelength with age until a threshold is crossed.
This research suggests that relief and roughness calculated from high-resolution topographic data of this study site could reflect alluvial fan morphology development and provide constraint data to differentiate alluvial fan unit. 相似文献
17.
J. CASALI L. M. De SANTISTEBAN J. J. LOPEZ J. V. GIRALDEZ J. POESEN J. NACHTERGAELE M. GONI J. LOIZU M. A. CAMPO 《国际泥沙研究》2005,20(4):295-304
1 INTRODUCTION Erosion caused by ephemeral flows is a frequent phenomenon in nature and contributes to the shape of the landscape. This type of erosion may cause great soil losses in agricultural areas, which are quickly transferred to the watershed outlets through the rill and gully network (Bennett et al., 2000; Poesen et al., 2003). Concentrated flow erosion is controlled by the erodibility of surface materials, climate, soil use and management, and watershed topography. Several metho… 相似文献
18.
Impact of anthropogenic drivers on subaqueous topographical change in the Datong to Xuliujing reach of the Yangtze River 总被引：3，自引：0，他引：3
Shuwei Zheng Heqin Cheng Shengyu Shi Wei Xu Quanping Zhou Yuehua Jiang Fengnian Zhou Minxiong Cao 《中国科学:地球科学(英文版)》2018,61(7):940-950
Changes of subaqueous topography in shallow offshore water pose safety risks for embankments,navigation,and ports.This study conducted measurements of subaqueous topography between Datong and Xuliujing in the Yangtze River using a Sea Bat 7125 multi-beam echo sounder,and the channel change from 1998 to 2013 was calculated using historical bathymetry data.The study revealed several important results:(1)the overall pattern of changes through the studied stretch of the river was erosion–deposition–erosion.Erosion with a volume 700×10~6m~3occurred in the upper reach,deposition of about 204×10~6m~3occurred in the middle reach,and erosion of about 602×10~6m~3occurred in the lower reach.(2)Dunes are the most common microtopographic feature,accounting for 64.3%of the Datong to Xuliujing reach,followed by erosional topography and flat river topography,accounting for 27.6%and 6.6%,respectively.(3)Human activities have a direct impact on the development of the microtopography.For instance,the mining of sand formed holes on the surface of dunes with lengths of 20–35 m and depths of 3–5 m.We concluded that the overall trend of erosion(net erosion volume of 468×10~6m~3)occurred in the study area mainly because of the decreased sediment discharge following the closure of the Three Gorges Dam.However,other human activities were also impact factors of topographic change.Use of embankments and channel management reduced channel width,restricted river meandering,and exacerbated the erosion phenomenon. 相似文献