共查询到20条相似文献，搜索用时 46 毫秒
1.
2.
The main forms of the impact of man-made lakes on terrestrial fauna populations and communities are considered. Peculiarities of the effect of man-made lakes on zoocomplexes in the upper and lower pools of hydraulic structures are analyzed. Approaches to developing measures aimed at decreasing environmental damage caused by reservoir construction are substantiated. 相似文献
3.
M. V. Martynova 《Water Resources》2006,33(6):670-676
Direct stochastic relations between organic matter destruction in the water column and the rate of substance sedimentation onto reservoir bed, as well as the correlation between plankton primary production and the rate of substance sedimentation onto the beds of lakes and reservoirs are discussed. The vital activity of bacterial biomass colonizing mineral particles as the latter settle onto the bottom is asserted to be the mechanism forming the aforesaid relations. 相似文献
4.
随着经济社会的快速发展和进步,我国湖库水体富营养化情况越来越严重.卫星遥感在水体营养状态监测方面具有重要潜力,但基于卫星遥感的全国范围内湖库水体营养状态监测和分析方面还鲜有研究.本文基于2018夏季的MODIS卫星遥感数据生产FUI指数产品,构建基于FUI水色指数的湖库营养状态评价方法,监测全国范围内144个重点湖库水体的营养状态等级.结果表明：贫营养、中营养、富营养的湖库比例分别为16%、24%、60%;营养状态在空间上分布不均匀,总体上呈现东高西低的现象;东北山地与平原和东部平原湖区以富营养状态水体为主;西部湖库水体以贫到中营养状态为主,尤其是青藏高原湖区贫营养比例比较高;海拔和地表温度等自然因素与工业点源和农业面源污染等人为因素是湖库营养状态的重要影响因素. 相似文献
5.
湖北省是长江中游重要的湖泊分布区,在历史时期湖泊分布广阔,是著名的云梦泽的主体.由于江湖关系演变和人类活动的影响,湖泊面积变化迅速,尤以20世纪为甚.本文在野外调查和历史文献分析的基础上,利用不同时期的水利图、地形图、遥感影像图作为基本信息源,在GIS技术支持下,提取湖泊水域信息,对湖北省湖泊的主要分布区--江汉平原近百年湖泊水域变化进行了研究.结果表明,从20世纪20年代开始湖泊面积和个数呈先增加后减少的趋势,50年代处于鼎盛时期,50年代到70年代迅速减少,70年代至2000年减幅明显减缓.这种动态变化是自然因素和人类活动综合作用的结果,人类活动的作用更为突出.湖泊面积的减少,带来一系列生态环境问题.针对湖泊资源日益减少的现状,文章提出了治理对策和建议. 相似文献
6.
The chemical characteristics and phytoplankton biomass (measured as chlorophyll-a concentrations) of seven lakes and one reservoir in the Ethiopian rift-valley were studied during the wet and dry seasons between 1990 and 2000. Mean concentrations of three major plant nutrients (nitrate-nitrogen, soluble reactive phosphorus, and silicate) increased during the wet seasons in four of the seven lakes, presumably as a result of mixing events and input from runoff. The changes in the major nutrient concentrations in the rest of the lakes were variable, but concentrations were usually higher during the dry seasons, most likely as a response to temporal variation in the phytoplankton biomass. pH measurements of the lakes did not show marked differences between the wet and dry seasons. Salinity (measured as conductivity) and total ions seemed to increase during the wet seasons in some of the lakes, possibly as a result of inflows that might carry high concentrations of solutes due to the heavy rains. Chlorophyll-a concentrations were higher during the dry seasons in most lakes except in three relatively more productive lakes. The results suggest that there could be light limitation in some of the Ethiopian rift-valley lakes, and events associated with the wet and dry seasons could bring about contrasting changes in nutrient levels and phytoplankton biomass in lakes, depending on the physical characteristics of the lakes. 相似文献
7.
江苏省五大湖泊水体重金属的监测与比较分析 总被引：4，自引：2，他引：2
2001—2011年(不含2004年)10年间对江苏省五大湖泊(太湖、滆湖、洪泽湖、高宝邵伯湖和骆马湖)的水体重金属浓度进行长期定点监测,按系统分组资料进行方差分析,以比较各重金属浓度在湖泊间的差异显著性,并在此基础上应用多指标综合评价法(TOPSIS法)对5个湖泊水体重金属进行综合比较.结果表明:除铜浓度外,5个湖泊间铅、镉、汞和砷4个指标浓度均存在极显著差异;5种重金属浓度湖泊内站位间均差异不显著;铅、镉和汞浓度站位内年份间差异显著或极显著.TOPSIS分析结果表明,总体而言高宝邵伯湖水体重金属污染程度最小,骆马湖水体重金属污染程度最大,洪泽湖、太湖和滆湖水体重金属污染综合评价优劣相当. 相似文献
8.
Brook Lemma 《Limnologica》2003,33(1):44-53
Alemaya and Hora-Kilole are small lakes found in central and southeastern parts of Ethiopia at similar altitudes. These lakes are exposed to contrasting human interventions. From Lake Alemaya water is withdrawn, while water is added to Lake Hora-Kilole because agricultural experts diverted flow from an adjacent river by constructing a weir. As a result, Lake Alemaya is continually shrinking due to uncontrolled water withdrawal for irrigation and municipal uses but Lake Hora-Kilole, now a reservoir, has increased in volume. Such uncontrolled contrasting anthropogenic intervention has caused ecological changes as observed from various limnological parameters. The problems of conserving these two tropical African lakes and the plankton contained in them are noted. Based on the present scenario, suggestions are forwarded as to what should be done with these lakes and similar situations elsewhere in the tropics. 相似文献
9.
10.
《Earth and Planetary Science Letters》2006,241(3-4):413-421
We studied the apparently old radiocarbon ages from lakes in the dry valleys of Antarctica. The radiocarbon reservoir effect in these lakes results from two components: the inherited age and the residence age. The inherited age is derived from input of old carbon, primarily from subsurface melt of adjacent glaciers. The residence age comes from in situ aging of lake water in an environment sealed from the atmosphere. Our results indicate that surface melt of glaciers introduces little ancient carbon to the lake system, because of rapid gas equilibration with the atmosphere. Subsurface melt in lakes with large glacier cross-sectional areas at the grounding line, however, can contribute a significant amount of ancient carbon, leading to lake-bottom reservoir effects in excess of ∼ 2700 yr. This value can increase to ∼ 20,000 yr immediately at the grounding line. In most lakes, however, surface melt far exceeds that from the subsurface and dilutes the effect of ancient carbon, making the inherited age relatively low. Residence ages generally are on the order of a few thousand years, but can be as much as ∼ 10,000 yr. Because a residence age is reset when the lake loses its ice cover and is exposed to wind-driven mixing, its magnitude can provide important information about lake history. 相似文献
11.
B. HENDERSON-SELLERS 《水文科学杂志》2013,58(4):363-367
ABSTRACT It is shown that a numerical model for predicting the depth time variation of water temperature in a fresh water lake or reservoir can be used also for prediction of water losses due to evaporation. The seasonal change in peak evaporation from summer (in small lakes) to winter (in large lakes) is satisfactorily simulated. 相似文献
12.
广东省水库富营养化评价 总被引：13，自引：2，他引：11
广东省水库水环境质量调查评价结果表明：广东省水库水质总体较好,但不同程度地发生了富营养化;在汛期,被 评价的132座水库中中营养型水库111座,中富营养型水库12座,富营养化水库2座;非汛期,中营养型水库111座,中富 营养型水库11座,富营养化水库1座．造成水库富营养化的主要原因是面污染的日益加剧、城市污水排放量的激增、水土 流失造成水库泥沙淤积严重、水库蓄水量减少等．水库的富营养化影响了其使用功能．为恢复富营养水库的使用功能,其 对策主要是减少面污染物排放量、提高污水处理率、加强水土流失的治理、清除淤泥等． 相似文献
13.
14.
宁夏西吉县滥泥河流域在1920年海原8.5级大震时形成大量黄土滑坡及堰塞湖。本文阐述了西吉县境地震滑坡地貌的基本特征和当地人民对滑坡地貌的开发利用现状,分析了地震滑坡地貌所产生的环境灾害隐患,并针对该地区因地制宜开发利用滑坡地貌的减灾对策进行了探讨。 相似文献
15.
广东流溪河水库后生浮游动物生物量谱时空异质性 总被引：4，自引：2，他引：4
于2001年4月至2002年12月调查了流溪河水库后生浮游动物,建立后生浮游动物乍物量谱并分析了其时空分布特征．后生浮游动物Sheldon型生物量谱并不是平谱,生物量随着浮游动物粒径(等效球体直径,ESD)的增大而增大．轮虫在粒径大小范围为50-160μm内生物量随着粒径的增大而减少;枝角类(100-512μm ESD)的生物量谱呈‘单峰型’．最大生物量出现在中等大小的粒径组(200-256μm)．桡足类的生物量大约占总后生浮游动物生物量的60％,为水库后生浮游动物最重要的组成部分;粒径分布范围较宽,覆盖了轮虫和枝角类．总体而言,桡足类生物量随着粒径的增大而逐渐增大．河流区后生浮游动物标准生物量谱斜率为-0．75;湖泊区标准生物量谱斜率为-0．58在河流区．后生浮游动物生物量中轮虫和无节幼体所占的比例要高于湖泊区,而湖泊区温中剑水蚤和舌状叶镖水蚤的成体和晚期桡足幼体所占的比例高于河流区．由于河流区小个体的优势度大于湖泊区,因此河流区后生浮游动物标准谱的斜率小于湖泊区.从后生浮游动物大小分布的季节性变化看,湖泊区季节性变化不明显;河流区则变化显著,丰水期标准化谱的斜率大于-0．75．枯水期小于-0.75,斜率的变化与水位波动呈正相关关系．水库库盆的形状及水动力学的时空差异可能是影响浮游动物大小分布时空差异的重要非生物因素之一． 相似文献
16.
V. B. Smirnov V. O. Mikhailov A. V. Ponomarev K. Arora R. K. Chadha D. Srinagesh M. G. Potanina 《Izvestiya Physics of the Solid Earth》2018,54(4):632-640
The spatial and time dynamics are analyzed for the seasonal components of induced seismicity in the Koyna–Warna region of Western India. The peculiarities of the variations in these components are compared to the changes in the local tectonic regime inferred from the focal mechanism data of the earthquakes. Based on this, the hypotheses about the probable nature of the dynamics in the seasonal components of seismicity are suggested. It is noted that the variations in the seasonal seismic activity after the impoundment of the Koyna reservoir in the north are caused by the spatial migration of the induced seismicity and activation of the normal faults in the south. It is hypothesized that the process of fracture migration from the north to the south at this stage advanced the diffusion of the fluid from the Koyna reservoir, and as the water front reached the southern zone of normal faulting, this caused reactivation of the seasonal seismicity. An explanation is suggested for the stronger response of the seasonal activity in the region of Warna reservoir compared to the Koyna area: in contrast to Koyna, filling the Warna reservoir was geographically close to the area of activated seismicity. It is shown that the localization and sizes of the areas of the instantaneous and delayed components in the seasonal activity of the induced seismicity are determined by the localization and sizes of the areas of high stresses created by the increase in the pore pressure in highly permeable fault zones. 相似文献
17.
三峡水库运行后长江中游洪、枯水位变化特征 总被引：3，自引：2，他引：1
流域大型水库蓄水后,坝下游河道调整过程中的洪、枯水位变化,对下游水安全、水生态和水资源利用影响甚大.利用1955-2012年长江中游各水文站水位、流量等资料,采用改进的时间序列分析方法,对三峡水库运行前后长江中游洪、枯水位变化特征进行了研究,结果表明:三峡水库蓄水前长江中游洪、枯水位变化的周期长度分别为9~14、11~15 a,在假设三峡水库运行后水位无趋势性变化的前提下,估算得到的水位变化周期长度基本在20 a以上,蓄水前的自然周期性已被打破,枯水位发生趋势性下降且无复归迹象,而洪水位波动周期虽有所延长,但上升幅度未超过历史波动变幅,仅可确定洪水位没有明显的下降趋势.三峡水库蓄水后坝下游长距离冲刷,枯水河槽冲刷量占平滩河槽的比例逐年增加,累计至2013年已达91.5%,是枯水位下降的主控因素.河槽冲刷导致的床沙粗化增加了河道床面阻力,高程在平滩水位附近的滩体上覆盖的大量植被增加了水流流动阻力,同时大量航道整治、护岸、码头等工程主体部分布设在枯水位以上,综合因素作用使得洪水河槽阻力增加.三峡水库蓄水后,虽然枯水期流量补偿作用显著削弱了枯水位下降的效应,但枯水位下降事实已经形成,不利于航道水深的提高及通江湖泊枯水期的水量存蓄,洪水位未明显下降,同级流量下的江湖槽蓄量不会明显调整. 相似文献
18.
Machine learning-based automatic construction of earthquake catalog for reservoir areas in multiple river basins of Guizhou province,China 
下载免费PDF全文
下载免费PDF全文 Large reservoirs have the risk of reservoir induced seismicity. Accurately detecting and locating microseismic events are crucial when studying reservoir earthquakes. Automatic earthquake monitoring in reservoir areas is one of the effective measures for earthquake disaster prevention and mitigation. In this study, we first applied the automatic location workflow (named LOC-FLOW) to process 14-day continuous waveform data from several reservoir areas in different river basins of Guizhou province. Compared with the manual seismic catalog, the recall rate of seismic event detection using the workflow was 83.9%. Of the detected earthquakes, 88.9% had an onset time difference below 1 s, 81.8% has a deviation in epicenter location within 5 km, and 77.8% had a focal depth difference of less than 5 km, indicating that the workflow has good generalization capacity in reservoir areas. We further applied the workflow to retrospectively process continuous waveform data recorded from 2020 to the first half of 2021 in reservoir areas in multiple river basins of western Guizhou province and identified five times the number of seismic events obtained through manual processing. Compared with manual processing of seismic catalog, the completeness magnitude had decreased from 1.3 to 0.8, and a b-value of 1.25 was calculated for seismicity in western Guizhou province, consistent with the b-values obtained for the reservoir area in previous studies. Our results show that seismicity levels were relatively low around large reservoirs that were impounded over 15 years ago, and there is no significant correlation between the seismicity in these areas and reservoir impoundment. Seismicity patterns were notably different around two large reservoirs that were only impounded about 12 years ago, which may be explained by differences in reservoir storage capacity, the geologic and tectonic settings, hydrogeological characteristics, and active fault the reservoir areas. Prominent seismicity persisted around two large reservoirs that have been impounded for less than 10 years. These events were clustered and had relatively shallow focal depths. The impoundment of the Jiayan Reservoir had not officially begun during this study period, but earthquake location results suggested a high seismicity level in this reservoir area. Therefore, any seismicity in this reservoir area after the official impoundment deserves special attention. 相似文献
19.
湖泊作为一种蓄水单元,尤其是大型过水性湖泊,是一种典型的平原型水库,在功能上与山谷型水库具有许多相似之处,但由于其特殊的地理地形构造,使得入湖洪水过程与入库洪水过程存在着较大的差异.在防洪安全设计研究中,山谷型水库关注的多是坝址洪水,即总的入库洪水过程,而对于湖泊来说,还需要关注各个分区的入湖洪水过程对湖区洪水演进的影响.针对大型过水性湖泊入湖洪水特征,本文采用Copula函数构造了多个联合分布函数,提出了一套基于总的入湖洪水过程推导各个分区入湖洪水过程置信区间的方法.以洪泽湖为应用实例,结果表明:1)在联合重现期已知的情况下,该方法能够确定总入湖洪量与洪峰的95%置信区间;2)该方法通过径流相关性分析对入湖河道合并聚类,形成分区入湖过程,既考虑了河道间天然的水文、水力联系,又避免了联合分布函数维度过高的问题;3)在总入湖洪量已知的情况下,该方法能够确定各分区入湖洪量分配95%置信区域.该方法具有较强的统计理论基础,拓展了多变量洪水频率分析技术在水利工程实际中的应用范围. 相似文献
20.