共查询到20条相似文献,搜索用时 31 毫秒
1.
洞庭湖区的泥沙淤积效应 总被引:7,自引:0,他引:7
以1951-2005 年长系列实测泥沙等资料为依据, 从泥沙淤积特性与资源环境之间的关系上, 探讨了洞庭湖区的泥沙淤积效应。研究表明: 由于洞庭湖区始终处于淤积状态, 加之人类活动影响, 导致了泥沙淤积循环演进的格局, 以至于使泥沙的灾害性效应与资源性效应 均在湖区得到充分的显示。主要表现在: ① 塑造了水体滩地、泥沙滩地、湖草滩地、芦苇滩地等类型滩地, 构成了湖泊巨系统的主体; ② 孕育或诱发了泥沙淤积→洲滩扩展、围垦→调洪功能下降、鱼类资源枯竭、生物多样性减少灾害链: 泥沙淤积→洲滩扩展→洪涝、水质污染; 泥沙淤积→植被洲滩浮涨→血吸虫病、害鼠致害灾害链; 泥沙淤积→洪溃决堤→土地沙 化灾害链。这些淤积型泥沙灾害链给湖区直接或间接地造成巨大的经济损失。③ 近55 年间, 泥沙塑造土地约98.13×108hm2, 人类合理开发利用洲滩资源获得了巨大的经济效益, 就地挖沙加高防洪大堤2~3 m, 累积土石方约55×108 m3, 节省了购买大量原材料的开支。 相似文献
2.
洞庭湖区的泥沙淤积效应 总被引:4,自引:1,他引:3
According to a long series of measured sediment data, the sedimentation effects of the Dongting Lake Area (DLA) were studied in light of the relationship between sedimentation characteristics and resources and environment. The result shows that the long-term deposi- tion and the impact of human activities have led to a cycle of the evolution of sedimentation pattern, resulting in sediment disaster effects and resources effects in the DLA. The main features are as follows: 1) The water beach, silt beach, lake marsh beach, reed beach and other types of beach shaped by sedimentation effects constitute the main body of the giant lake system. 2) The disaster chains are induced, i.e., sedimentation → marshland expansion and reclamation → flood function decline, fish resource depletion, biodiversity reduction dis- aster chain, sedimentation → marshland expansion → floods, water pollution disaster chain, sedimentation → marshland floating vegetation rising → schistosomiasis, rodents virulence disaster chain, sedimentation → flood embankment bursting → land desertification disaster chain. 3) Sedimentation has created about 98.13×104hm2 of land in the past 55 years. Ra-tional development and utilization of marshland resources have produced tremendous eco- nomic benefits. 相似文献
3.
近60年洞庭湖泊形态与水沙过程的互动响应 总被引:2,自引:0,他引:2
以历史文献、图件及1951~2009年长系水沙等资料为依据,对比分析洞庭湖形态与水沙过程的互动响应,结果表明:由于湖泊形态与水沙过程存在着相互作用的关系,近60年间,水沙过程以多种形式改变湖泊形态特征值,如湖盆结构破碎、解体,水深变浅以及湖面﹑湖容依次减少1840km2及130×108m3;同时湖泊形态特征值改变也引起水沙特性变异,在1951~2002年间湖盆蓄水量呈明显的增减波动,但同流量下汛期水位普遍抬高1.2~1.90m,西﹑南﹑东洞庭湖水位变幅依次增大1.61m、1.39m和1.35m,各主要水文站前5位最高洪水位排序的年份均出现在湖面积(容积)历史最低值,泥沙淤积率为70%以上;2003年6月三峡水库蓄水及"退田还湖"后,高、中水位下湖盆调蓄量有所减少,城陵矶丰、枯水位分别降低1.12m及0.35m,西湖区与东南湖区的泥沙输出比均呈增大趋势,泥沙淤积率减至35.9%。其互动响应机制,可概化为泥沙淤积循环→湖盆结构破碎、解体,湖面湖容缩小→水沙特性异变→改变湖泊形态→水沙特性变异的互动响应动态演进模式。 相似文献
4.
开封市黄河滩区土地资源规避洪水风险的安全利用 总被引:2,自引:1,他引:1
基于ArcGIS与ERDAS遥感影像制图软件,利用2007年SPOT2.5m分辨率遥感影像,结合实地调查,详细编绘了开封市段黄河河道边界、开封段黄河滩区土地资源的利用现状。采用1992~2007年最大洪峰时期的TM影像与沿河水文站点的观测资料,提取1992~2007年7个典型日期的河道行洪边缘线,与本底数据叠加,编制了开封段不同常遇洪水流量下滩区淹没范围。按照黄河下游二维水沙数学模型,采用2004年汛后河道大断面资料,计算生成不同流量级大洪水在滩区的可能淹没范围图(淹没区边界)。在此基础上,结合土地资源管理与河道行洪安全性的要求,总结当前黄河下游滩区利用开发的现状与存在问题,制订土地安全利用规避洪险的原则,规划土地安全利用分区,分为临河风险缓冲带、近河宜耕地带、相对稳定利用带(中风险带)和稳定利用带。提出了黄河滩区土地资源合理安全利用的对策。 相似文献
5.
水沙过程变化下洞庭湖区的生态效应分析 总被引:1,自引:0,他引:1
依据1951-2009年实测水文数据及多年实地考察资料,对比分析水沙过程变化对洞庭湖区生物群落及其生存环境的影响.结果表明:(1)水沙过程对生物群落及其生存环境具有多方面的生态支撑作用,水沙动态是洞庭湖生态系统的控制性变量;(2)泥沙的不断淤积,使各类植被洲滩发育与扩展,导致湖面缩小及调蓄功能减弱和天然捕捞鱼场减少;(3)各类植被洲滩相继出露和湖水位涨落交替过程,不但维系着东方田鼠种群数量及迁移的延续,还支撑着钉螺(血吸虫的中间宿主)的孳生和繁衍;(4)入湖水沙量的逐期减少,削弱了水域环境的净化能力,“四 相似文献
6.
《The Professional geographer》2013,65(4):434-445
Abstract Jiangxi Province in southeastern China contains Poyang Lake, the largest freshwater lake in China. Poyang Lake and the lower sections of the major Jiangxi rivers flowing into the lake often flood during the early summer months. Floodwater can be several meters above the surrounding lowlands during the most severe flood events. Levees at the margins of Poyang Lake and along the Jiangxi rivers provide flood protection for about 10 million people. The number of severe floods in this region has increased rapidly during the past few decades, resulting in catastrophic levee failures. The three factors likely responsible for the increasing frequency of severe floods are (1) land reclamation and levee construction and (2) lake sedimentation, both of which reduce lake volume, and (3) increasing Changjiang water level, which slows Poyang Lake drainage. 相似文献
7.
黄河内蒙古河段非汛期和汛期冲淤量计算方法 总被引:1,自引:0,他引:1
基于多沙河流“多来多排”的经验输沙公式,建立了考虑上站来沙量、前期河床累计淤积量、临界输沙水量及干支流泥沙粒径影响的非汛期和汛期输沙量一般表达式。在此基础上,根据黄河内蒙古河段1952-2010年实测的水沙资料,将其应用于黄河内蒙古河段巴彦高勒—三湖河口河段、三湖河口—头道拐河段以及巴彦高勒—头道拐全河段非汛期和汛期输沙量的计算,并应用输沙率法计算了各河段1952-2010年的非汛期和汛期冲淤量及其相应的累计冲淤量。通过输沙量、冲淤量和累计冲淤量计算值与实测值的对比表明,各河段非汛期和汛期输沙量、冲淤量及相应的累计淤积量计算值与实测值的吻合较好,其中非汛期和汛期输沙量计算值和实测值之间的相关系数R2分别约为0.93和0.97;非汛期和汛期冲淤量计算值与实测值之间的相关系数R2分别约为0.80和0.90;非汛期和汛期累计冲淤量之间的相关系数R2分别约为0.94和0.99。结果表明,就吻合程度而言,累计冲淤量优于年冲淤量,汛期优于非汛期。本文建立的冲淤量方法能够很好模拟该河段长历时的非汛期和汛期冲淤过程,可为黄河内蒙古河段输沙量及长期淤积发展趋势的分析提供科学依据。 相似文献
8.
H. Cremer F. P. M. Bunnik T. H. Donders W. Z. Hoek M. Koolen-Eekhout H. H. Koolmees E. Lavooi 《Journal of Paleolimnology》2010,44(3):789-801
A 400-year sediment record from an 18 m deep scour hole lake (Haarsteegse Wiel) near the Meuse River in the Netherlands was
investigated for past changes in water quality, flooding frequency and landscape change using geophysical, geochemical and
micropaleontological information. The results are highly significant for determining long-term trends of water quality, the
impact of atmospheric (as SCP, spheroidal carbonaceous particles) and industrial (chromium) pollution on the terrestrial and
aquatic flora, and the impact of river floods. The studied sediment record was dated by combining 137Cs activities, biostratigraphical ages, micro-tephra layers, and historically documented floods indicated by the magnetic
susceptibility. The oldest flooding event is indicated at AD 1610 when the lake was created by water masses bursting through
a dike. Large historical river floods are well documented in regional chronicles and thus may provide reliable age calibration
points. Based on assumptions about the timing of flood events and constant rate of sedimentation, it appears that sedimentation
rates in Haarsteegse Wiel declined after ca. AD 1880. This decline might be a result of a widespread change from wheat cultivation
to pasture land from around AD 1875 as a direct result of falling wheat prices and intensified cattle farming linked to the
agricultural crisis in the last quarter of the nineteenth century. Water quality changes and absolute phosphorus concentrations
were reconstructed using a diatom-based transfer function. Results show that the currently nutrient-rich lake has mostly been
in a mesotrophic state prior to ca. AD 1920, with the exception of several apparently sharp eutrophication events that were
coeval with river floods. River flooding also impacted the vegetation composition by importing allochthonous components, and
indirectly by the influx of nutrients which had a clear influence on the composition of the water plant communities and aquatic
species diversity. Magnetic susceptibility changes and pollen data show that within the period AD 1610–1740, within the Little
Ice Age period, several undocumented floods may have occurred. Thus, documentation of geophysical, geochemical, and biological
flooding signals in a high-resolution archive present the possibility to detect flooding regimes further back in time. 相似文献
9.
Jiangxi Province in southeastern China contains Poyang Lake, the largest freshwater lake in China. Poyang Lake and the lower sections of the major Jiangxi rivers flowing into the lake often flood during the early summer months. Floodwater can be several meters above the surrounding lowlands during the most severe flood events. Levees at the margins of Poyang Lake and along the Jiangxi rivers provide flood protection for about 10 million people. The number of severe floods in this region has increased rapidly during the past few decades, resulting in catastrophic levee failures. The three factors likely responsible for the increasing frequency of severe floods are (1) land reclamation and levee construction and (2) lake sedimentation, both of which reduce lake volume, and (3) increasing Changjiang water level, which slows Poyang Lake drainage. 相似文献
10.
Combined analyses of pollen, seeds, woods, micro-charcoal and non-pollen palynomorphs from Stagno di Maccarese, an artificially
dried out coastal basin north of the Tiber delta now occupied by the Fiumicino Airport (Rome, Italy), document marked vegetation
and environmental changes during the last 8300 years. Between 8300 and 5400 cal. a BP dense mixed deciduous and evergreen
forests surrounded a eutrophic freshwater basin. An abrupt change around 5400 cal. a BP marks the transition to a marshy environment,
due to a lowering of the water table. An increase of cereals and micro-charcoals matches the presence of a nearby Eneolithic
settlement. Between 5100 and 2900 cal. a BP there is a remarkable expansion of riparian trees, indicating an increase of the
water level. Between 2900 and 2000 cal. a BP, a new development of marshlands points to a progressive lowering of the lake.
After 2000 cal. a BP, during the Roman exploitation of the area, an expansion of arboreal vegetation is recorded, characterized
by evergreen and deciduous oak-dominated forests, while an extensive chenopods marshland matches the presence of saltworks.
On the whole, the Stagno di Maccarese area appears very unstable, due to changes in lake level, introgression of marine water,
eutrophic phases, flood events, desiccations and openings of the forest vegetation. 相似文献
11.
Historical change in lake sedimentation in Lake Takkobu, Kushiro Mire, northern Japan over the last 300 years 总被引:1,自引:0,他引:1
Environmental degradation, including shallowing, deterioration of aquatic habitat and water pollution, has arisen from the inflow of fine sediment to Lake Takkobu in northern Japan. The lake has experienced gradual environmental degradation due to agricultural development, which has introduced both fine sediment and sediment-associated nutrients into the lake. We have reconstructed the history of sediment yield to Lake Takkobu in Kushiro Mire over the last 300 years and have examined trends with reference to land-use development. Fifteen lake sediment core samples were obtained, and various physical variables of lake sediments were analyzed and dated using 137Cs and tephrochronology. The physical variables showed that all points contained mainly silt, except for two points close to the river mouths, where the mean diameter was < 35 μm. The peaks were defined as a “signal” when the physical variables were synchronous in a profile. These were created by floods and engineering works constructing drainage systems. The signal of canal construction in 1898 was detected in all core points. Lake Takkobu core samples contained two tephra layers. From the refractive indices of dehydrated glasses, the lower tephra layer was identified as Ko-c2 (1694) and the upper tephra layer as Ta-a (1739). A clear peak in the 137Cs concentration was detected at all the sampling points, except for the site close to the Takkobu River. This site showed two peaks in the 137Cs concentration, which was attributed to perturbation from flood events and a drainage project. The maximum 137Cs concentration was identified as the sediment surface from 1963, enveloped by the 1962 and 1964 signals. The sediment yield averaged over the last 300 years for Lake Takkobu was reconstructed for four periods using the signal, tephra and 137Cs as marker layers. The sediment yield under the natural erosion condition for the first two periods was 226 tons/year from 1694 to 1739 and 196 tons/year from 1739 to 1898. The development of the Takkobu watershed started in 1880s with partial deforestation and channelization in 1898, 1959, and 1962 leading to an increased sedimentation yield of 1016 tons/year from 1898 to 1963. Continued deforestation, channelization works in 1964, road construction in 1980–1990s, as well as agriculture development caused a further increase to 1354 tons/year from 1963 to 2004. Compared to the averaged natural sedimentation yield of 206 tons/year until 1898, initial land-use development in a catchment accelerated lake sedimentation, indicated by the 5-fold sediment yield. With increasing agricultural development since 1960s, sedimentation yields were highest for 1963–2004; a 7-fold increase compared with pre-impact conditions. To reduce sediment yield, riparian buffers along the rivers should be preserved or rebuilt, and sluices may function effectively during short-term periods of flooding. Environmental management policy and laws restricting uncontrolled and inappropriate land-use might help in addition to ensure longer-term environmental health by reducing the sedimentation rate. 相似文献
12.
13.
14.
三峡工程建设背景下的洞庭湖区治水方略探讨 总被引:8,自引:1,他引:7
在长江三峡工程建设的大背景下,本文分析了洞庭湖区的水灾减灾机制,探讨了洞庭湖区的治水方略,提出应充分发挥三峡水库的调蓄功能,协调江湖关系,改善冲淤关系,加强水利工程建设,实现三峡水库与湖南四水水库的优化调度 相似文献
15.
Water and sediment chemistry of Lake Pumayum Co,South Tibet,China: implications for interpreting sediment carbonate 总被引:2,自引:0,他引:2
Jianting Ju Li-ping Zhu Junbo Wang Manping Xie Xiaolin Zhen Yong Wang Ping Peng 《Journal of Paleolimnology》2010,43(3):463-474
A combination of water and sediment chemistry was used to investigate carbonate production and preservation in Lake Pumayum
Co (altitude 5,030 m a.s.l.), south Tibet, China. We compared the chemical composition of lake water in various parts of the
lake with that of input rivers and found that the loss of Ca2+ results from calcite sedimentation induced by evaporation and biogenic precipitation. This is supported by evaporation data
from the catchment and δ18O measurements on water. Results suggest that CaCO3 is the predominant carbonate in this lake. There is a positive correlation in the sediments among concentrations of total
inorganic carbon (TIC), Ca, total organic carbon (TOC), and total nitrogen, confirming that most carbonates in sediment are
endogenic. The Jiaqu River is the largest inflow to Lake Pumayum Co and has a strong influence on both lake water chemistry
and sediment composition. The river and lake bathymetry influence carbonate sedimentation by affecting water flow velocity
and growing conditions for macrophytes. Different carbon contents and relationships between TIC and TOC in the two long cores
from different depths in the lake reveal that hypolimnetic conditions also influence carbonate precipitation and preservation. 相似文献
16.
土地利用/土地覆被变化对长江流域水环境的影响研究 总被引:15,自引:1,他引:15
不合理的土地利用方式/土地覆被变化已成为长江流域水环境不断恶化的重要原因之一,长江上游植被破坏和陡坡开垦造成严重的水土流失,直接威胁到三峡库区的生态安全,中流的围湖造田等损害了湖泊的生态功能,导致严重的洪涝灾害,化肥,农药的过量使用,农田污水灌溉等成为长江流域农业非点源污染的重要来源。文章提出了进一步研究构想,以山-河-湖-海互动系统为研究对象,以系统内各子系统之间的能量流和物质流的联系为纽带,揭示系统自组织、自反馈机制,利用遥感技术和地理信息系统结合数学模型,动态模拟土地利用/土地覆被变化的水文及水环境效应。 相似文献
17.
Mary Beth Day David A. Hodell Mark Brenner Jason H. Curtis George D. Kamenov Thomas P. Guilderson Larry C. Peterson William F. Kenney Alan L. Kolata 《Journal of Paleolimnology》2011,45(1):85-99
Tonle Sap Lake, Cambodia, possesses one of the most productive inland fisheries in the world and is a vital natural resource
for the country. The lake is connected to the Mekong River via the Tonle Sap River. Flow in the Tonle Sap River reverses seasonally,
with water exiting the lake in the dry season and entering the lake during the summer monsoon. This flood pulse drives the
lake’s biological productivity. We used Sr, Nd, and Pb isotopes and elemental concentrations in lake sediment cores to track
changes in the provenance of deposits in Tonle Sap Lake. We sought to determine when the lake first began to receive water
and sediment input via the Mekong River, which initiated flood pulse processes. The transition from a non-pulsing lake to
the Mekong-connected system is marked by shifts to values of 87Sr/86Sr, εNd, and 207Pb/204Pb that are characteristic of Mekong River sediments. In addition, magnetic susceptibility increased and sediment elemental
composition changed. Elemental (P) measures point to enhanced phosphorus loading and C/N and isotope ratios of bulk organic
matter indicate a shift to greater relative contribution of organic material from aquatic versus terrestrial environments,
coinciding with the initiation of flood pulse processes. On the basis of radiocarbon dating in two cores, we estimate the
initiation of the annual flood pulse occurred between ~4,450 and 3,910 cal year BP. 相似文献
18.
Sediment fingerprinting as an environmental forensics tool explaining cyanobacteria blooms in lakes 总被引:1,自引:0,他引:1
Cyanobacteria (blue-green algae) blooms in water bodies present serious public health issues with attendant economic and ecological impacts. Llyn Tegid (Lake Bala) is an important conservation and amenity asset within Snowdonia National Park, Wales which since the mid-1990s has experienced multiple toxic cyanobacteria blooms threatening the ecology and tourism-dependent local economy. Multiple working hypotheses explain the emergence of this problem, including climate change, land management linked to increased nutrient flux, hydromorphological alterations or changing trophic structure - any of which may operate individually or cumulatively to impair lake function. This paper reports the findings of a sediment fingerprinting study using dated lake cores to explore the linkages between catchment and lake management practices and the emergence of the algal blooms problem. Since 1900 AD lake bed sedimentation rates have varied from 0.06 to 1.07 g cm−2 yr−1, with a pronounced acceleration since the early 1980s. Geochemical analysis revealed increases in the concentrations of total phosphorus (TP), calcium and heavy metals such as zinc and lead consistent with eutrophication and a rising pollution burden, particularly since the late 1970s. An uncertainty-inclusive sediment fingerprinting approach was used to apportion the relative fluxes from the major catchment land cover types of improved pasture, rough grazing, forestry and channel banks. This showed improved pasture and channel banks are the dominant diffuse sources of sediment in the catchment, though forestry sources were important historically. Conversion of rough grazing to improved grassland, coupled with intensified land management and year-round livestock grazing, is concluded to provide the principal source of rising TP levels. Lake Habitat Survey and particle size analysis of lake cores demonstrate the hydromorphological impact of the River Dee Regulation Scheme, which controls water level and periodically diverts flow into Llyn Tegid from the adjacent Afon Tryweryn catchment. This hydromorphological impact has also been most pronounced since the late 1970s. It is concluded that an integrated approach combining land management to reduce agricultural runoff allied to improved water level regulation enabling recovery of littoral macrophytes offers the greatest chance halting the on-going cyanobacteria issue in Llyn Tegid. 相似文献
19.
Robert G. Hatfield Barbara A. Maher Jacqueline M. Pates Philip A. Barker 《Journal of Paleolimnology》2008,40(4):1143-1158
We examine sediment dynamics in an upland, temperate lake system, Lake Bassenthwaite (NW England), in the context of changing
climate and land use, using magnetic and physical core properties. Dating and analysis of the sedimentary records of nine
recovered cores identify spatially variable sedimentation rates across the deep lake basin. Mineral magnetic techniques, supported
by independent geochemical analyses, identify significant variations both in sediment source and flux over the last ∼2100 years.
Between ∼100 years BC and ∼1700 AD, sediment fluxes to the lake were low and dominated by material sourced from within the
River Derwent sub-catchment (providing 80% of the hydraulic load at the present day). Post-1700 AD, the lake sediments became
dominantly sourced from Newlands Beck (presently providing ∼10% of the lake’s hydraulic load). Three successive, major pulses
of erosion and increased sediment flux appear linked to specific activities within the catchment, specifically: mining activities
and associated deforestation in the mid-late nineteenth century; agricultural intensification in the mid-twentieth century
and, within the last decade, the additional possible impact of climate change. These results are important for all upland
areas as modifications in climate become progressively superimposed upon the effects of previous and/or ongoing anthropogenic
catchment disturbance. 相似文献
20.
William M. Last 《International Journal of Salt Lake Research》1993,2(1):47-58
Remarkably high rates of sedimentation (up to nearly 60 kg m−2 yr−1) are documented for offshore areas of Freefight Lake, a deep, hypersaline, meromictic lake in the northern Great Plains of
Canada. Most material in the offshore sediment traps consists of soluble and suparingly soluble endogenic salts. Deposition
of allogenic sediment is minor. The observed high sedimentation rates are in response to several mechanism: (i) freeseout
precipitation of salts from the mixolimnion; (ii) redistribution of shallow water endogenic precipitates by turbidity flows
and interflow processes; and (iii) precipitation of salts from within the monimolimnion Because the bottom water mass of the
lake is essentially isothermal and isochemical, large scale temperature induced remobilization of these salts at or near the
sediment-water interface is unlikely. Similarly, the morphology of the basin suggests that resuspension of bottom sediment
by waves in the offshore areas of the basin is negligible. Although the sedimentation rates observed in Freefight Lake are
extraordinarily high and considerably greater than other modern lacustrine sedimentation rates documented in the literature
to date, the observed rates are entirely compatible with suggested accumulation rates of ancient evaporite sequences.
Palliser Tringle Global Change Contribution Number 6. 相似文献