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1.
The Tseng-wen River is a small mountainous river in southern Taiwan that has distinct dry and flood seasons. Several lines of evidence have revealed that the depositional system at the mouth of the river has transformed from a deltaic system to an estuarine system. The evidence includes long to short-term shoreline changes, geomorphology of the river mouth, mixed sediment sources inside the river mouth, mixing and suspended sediment characteristics inside the river mouth, and the grain-size distribution patterns on the river bed. Unlike the long-term evolution of many other coastal systems, the transformation at the Tseng-wen River mouth is largely caused by the building of a reservoir in the middle reaches of the river. The present study provides an example that coastal environments can be influenced by human activities farther inland on a time scale much faster than what would occur naturally. 相似文献
2.
Flow and high sediment yield from the Huangfuchuan watershed 总被引：2，自引：2，他引：0
J. Sui Ph.D. Y. He Ph.D. B. W. Karney Ph.D. 《International Journal of Environmental Science and Technology》2008,5(2):149-160
This study deals with general features of sediment transport in the Huangfuchuan river, an important branch river of the Yellow river, draining the Loess Plateau in China. The long-term precipitation records at 3 climate stations near the watershed have been used to assess the changes in precipitation in this region. By introducing metrics for runoff and sediment transport, long-term observations on discharge and sediment concentration at the Huangfuchuan gauging station on the Huangfuchuan river have been used to assess the changes in runoff and sediment transport in the Huangfuchuan River compared with those at the Toudaoguai and Fugu gauging stations on the Yellow river. It is found that both runoff and sediment metrics have a clearly downward trend. From July to August, the long-term sediment transport modulus at the Huangfuchuan gauging station is much higher than those at the Toudaoguai and Fugu stations on the Yellow river. The long-term average sediment transport modulus at the Huangfuchuan gauging station are high, ranging from 14000. t/(km2 y) but decreasing to 5900 t/(km2 y) over the last 10 years. Additionally, analyses on grain size distribution of suspended load in the Huangfuchuan and Yellow river have been conducted. 相似文献
3.
渭河平原地下水分布特征与环境同位素研究——以白杨水源地为例 总被引：3，自引：0，他引：3
白杨水源地座落在渭河下游重镇——渭南市西北约5km处，为渭河冲积平原的一部分。区内第四纪松散堆积物巨厚，地形平坦，降水充沛，地表水丰富，为地下水储存提供了良好的空间。按含水介质的埋藏条件可划分为潜水、浅层承压水、中层承压水和深层承压水4个含水岩组。为了进一步研究地下水的补给形成机制、储存运移过程、排泄开采条件，本文结合环境同位素（包括14C、13C、3H、D和18O）对水源地地下水年龄、地下水运动速率以及一些水文地质参数进行研究和探讨。而同位素测定表明：水源地潜水为现代水，3H含量较高，河水补给量占1/2 相似文献
4.
水资源短缺和合理利用是干旱半干旱区黑河流域面临的一个严峻问题,解决问题的关键是要深入了解水循环机理,而分析不同水体中环境同位素变化特征是应用同位素示踪技术研究水循环机理所必须的前提。根据测得的黑河流域降水、河水和地下水中δ18O,分析了取样期间不同水样δ18O的变化,揭示了降水中δ18O存在显著的温度效应、季节效应、高程效应以及与降水量的正相关关系;河水中δ18O的时空变化特征,即出山口地区河水中δ18O统计值低于山区和盆地,山区河水中δ18O的时间分布与大气降水一致,出山口河水中δ18O时间分布与大气降水相反,河水中δ18O沿黑河流程存在显著递增趋势;地下水中δ18O在张掖变化幅度较大,在临泽较均一且9月份普遍高于6月份,而在高台则分为显著的2组,较高的一组9月份普遍低于6月份。研究了不同因素对水循环过程中δ18O变化的影响及相互作用,为同位素技术在黑河流域水循环研究中的应用提供科学依据。 相似文献
5.
通过黄河下游游荡性河道典型河段河势观测资料,统计分析了河势的调整关系。研究表明,尽管游荡性河道河势多变不定,但主流线在河宽方向的摆动位置仍有一定的统计规律可循;主流线弦高与弦长之间的调整符合弓形参数间的一般函数关系;随主流线长度增加,弯曲半径不会无限制减小,将会趋于某一相对稳定状态;弯曲系数与主流线长度、弯曲半径之间的统计关系表征了黄河下游游荡性河道河势易出现陡湾且易坐小湾坐陡湾的特性;弯曲半径与河面宽之间具有一定的相关趋势,河面越宽,弯曲半径增加的可能性越大。 相似文献
6.
本文采用流量级频率分析和统计分析方法,对黄河下游流量及泥沙含量对水环境容量的影响进行了研究分析.分析结果:河流在平滩流量时不仅输沙能力最大[8],而且输运污染物能力也最大,黄河下游水环境容量萎缩是平滩流量降低的必然结果. 相似文献
7.
高寒山区的地表水与地下水相互作用的定量研究对水资源的评价及管理等具有重要意义,而目前在高寒山区开展的地表水与地下水相互作用的定量研究相对较少.以黑河上游葫芦沟流域为研究区域,采用温度示踪方法对高寒山区河水与地下水的相互作用进行了研究,并对温度示踪方法在高寒山区的适用性进行了讨论.监测了研究区两个时段的地温、河水水位、地下水水位以及河床沉积物底部不同深度处的温度,并对温度系列数据进行定量分析,计算了不同位置处河水入渗流速.结果表明:研究区河水水位普遍高于地下水水位;河床底部温度在9月份整体低于7月;流速计算结果表明监测时段内主要为河水入渗补给地下水,入渗速率整体介于2×10-6~5×10-5 m/s.温度示踪法在高寒山区的适用性分析表明:在地下水受多途径补给时,温度示踪法仅指示河水对地下水的补给,而其他水源对地下水的补给还要通过同位素方法和数值模拟等其他手段进行计算.影响高寒山区河水对地下水补给的因素主要有:河水与地下水水位、河床沉积物的水力传导系数与热容. 相似文献
8.
西昆仑山前河流阶地的形成及其构造意义 总被引：4，自引：0，他引：4
西昆仑山前河流普遍发育6级阶地,利用光释光（OSL）与热释光（TL）方法对采自西昆仑山前几条主要河流的低阶地堆积物样品进行年代测定。研究结果显示,主要河流低阶地的形成具有同时性,构造活动是河流阶地形成的主要控制因素。河流阶地的年龄测定结果表明,西昆仑山前河流阶地最早形成于约1.2Ma,T4、T3、T2阶地分别形成于约39ka、18ka和5ka。多级阶地的形成反映了河流自早更新世中期开始下切于活动抬升的西昆仑山。河流阶地的发育及区域对比揭示了西昆仑第四纪晚期以来的隆升过程,区域构造活动明显地影响河流的形态与行为。河流阶地的分布、地貌特征及区域对比表明,河流阶地的形成与演化受新构造活动、山脉隆升、气候变化等多种因素的影响。 相似文献
9.
赵诚 《吉林大学学报(地球科学版)》1996,(4)
李四光有“黄陵背斜为华西、华东的分水岭，岭西之水流入归州盆地和四川盆地，岭东之水则向东流，袭夺……”的正确论断，但他“（袭夺）年代是第三纪末至早更新世初”的见解则过早。黄陵背斜西侧之水属古金沙江东支流，仅香溪至重庆段内竟有７３．３％的支流呈倒插；巫山至故陵镇８２．５ｋｍ间的Ｔ６、Ｔ５、Ｔ４阶地面沿江呈西倾，而Ｔ３、Ｔ２、Ｔ１阶地面沿江呈东倾，二者刚好反向。在重庆、奉节分别发现了鹅岭风口和白帝城风口，二者与倒插支流、反向阶地共同证实了此段属掉向（被袭夺）流段。由于２．０Ｍａ以来印度板块与亚欧板块碰撞所导致的西域上升，黄陵背斜遭冰后期和其它外营力剥蚀、降低，古金沙江南下水路被横断山封堵，西支流只好向东支流涌来，又借黄陵背斜东坡古长江向源侵蚀之机，终于０．１５～０．２０Ｍａ间切开黄陵背斜分水岭，形成新型长江 相似文献
10.
《Geoforum》2016
The sustainable management of China’s rivers is very important to the well-being of both the environment and its people. Yet the country’s rivers are now facing imminent threats from river overexploitation. The deteriorating condition serves as a stark reminder that relevant policies must be revised to ensure their wiser stewardship. In this short critical review, we first briefly stated river development history and various impacts arising from river overexploitation. We then elaborated the issues in river management, which connived numerous behaviors neglecting river degradation happened at all institutional levels. Based on the weakness, we proposed some policy recommendations to sustain China’s rivers and balance river development and conservation. The article concludes by proposing the development of a national river protection law to reinforce integrated river management, improve the implementation of environment impact assessments, and fulfill long-term goals for river conservation and sustainable development. 相似文献
11.
Measurements show that in general salt is vertically well-mixed everywhere in the Great Bay Estuary, New Hampshire except near the river entrances at the head of the estuary. Dyer and Taylor’s (1973) modified version of Ketchum’s segmented tidal prism model has been applied to the Great Bay Estuarine System in order to predict high and low water salinity distribution for a specified river flow. The theory has been modified here to account for the mixing which occurs at the junction of two branches of an estuary. The mixing parameter, which in this model is related to the tidal excursion of water in the estuary, has been determined for different segments in the estuary on the basis of a comparison between predictions and a comprehensive data set obtained for a low river flow period. Using a mixing parameter distribution based on the low river flow calibration procedure the salinity distribution has been predicted for high river flow. The resulting salinity distribution compares favorably with observations for most of the estuary. The corresponding flushing times for water parcels entering at the head of the estuary during periods of low and high river flow is 54.5 and 45.9 tidal cycles respectively. 相似文献
12.
中国金刚石砂矿主要分布在华北与扬子地台郯庐断裂区与沅水流域区 ,在大别山区及新疆、西藏超基性岩附近也有分布。不同时代的含金刚石金伯利岩或超基性岩带 ,经风化、剥蚀、搬运 ,形成含金刚石砂矿中间储存体 ,在水系中下游形成不同类型 (阶地、河谷、河床 )砂矿。金刚石砂矿找矿方向应是模式找矿主要有三方面 :一是矿源 ,二是中间储存体 ,三金刚石砂矿组合矿物。 相似文献
13.
珠江口的沉积作用和沉积相 总被引：6，自引：2，他引：6
珠江口为华南沿海的重要河口,是珠江水(系(西江、北江、东江、流溪河)的受水盆地。珠江流域每年有8000余万吨悬沙。大约3000万吨溶解质和少量底沙进入珠江河口区域,它们在迳流、潮流和其他海洋动力因素共同影响下,沉积作用甚为活跃。但是珠江口水域宽阔,地形复杂,各河口、河口湾或湾外区域的动力背景及泥沙运动不尽相同,因而其沉积作用和沉积特征也具有区域差异。 相似文献
14.
N. Janardhana Raju T. V. K. Reddy P. Muniratnam Wolfgang Gossel Peter Wycisk 《Journal of the Geological Society of India》2013,82(6):657-665
Overuse of groundwater in coastal areas, due to high population and agricultural activity results in seawater intrusion into the coastal aquifer. This paper presents the control measures taken to manage aquifer recharge (MAR) and also to overcome the problem of seawater intrusion into the coastal aquifer along the Kalangi river, Nellore district of Andhra Pradesh, India having connectivity with Pulicat (saltwater) lake estuary. Due to overexploitation of groundwater and less rainfall in past years, adjacent seawater has started intruding in the Kalangi river sub-surface and deteriorating groundwater quality up to 11.6 km from the confluence of the river with Pulicat lake. To prevent this situtation, subsurface dams were constructed in traditional manner using local earth material in three different places across the Kalangi river near Sullurpet town. The water storage capacities calculated after the sub-surface dams’ construction are 1.28 mcft at GK Engineering College, 6.23 mcft at Challamagudi and 3.143 mcft at Holy Cross School sites. The Holy Cross School sub-surface dam is the first full scale dam-cum-check dam constructed to prevent salt water intrusion in the Kalangi river at Sullurpet, Nellore district, Andhra Pradesh. At the Kalangi river estuary portion (at the mouth of sea) a groyne was reconstructed over old groyne site with the introduction of clay bed and wooden sheet piles at down stream. Apart from prevention of sea water entry into Kalangi river sub-surface (during seasons) the groyne top level was raised to prevent mixing of high sea water tides with fresh water and ensuring additional storage of fresh water at upstream side. The reconstructed groyne was serving the purpose of obstructing the surface seawater entry in the Kalangi river and water quality has improved in the river as well as in the wells. After construction of sub-surface dam, as per the Simpson ratio classification, there is substantial improvement of water quality in the SHAR infiltration well situated near the Holy Cross School sub-surface dam. 相似文献
15.
额尔齐斯河发源于中国新疆阿尔泰山南坡,是中国唯一流入北冰洋的河流。随着中俄“冰上丝绸之路”提出,额尔齐斯河通航具有重要意义,监测其河冰物候变化显得尤为必要。本研究基于2001—2018年MOD09GQ第2波段数据,分析了额尔齐斯河布尔津至斋桑泊段每年河冰物候信息,包括开始封河时间、结束开河时间、冰/雪最大覆盖时间、冰期持续时间、封河速率和开河速率。研究结果表明：（1）MOD09GQ的反射率随河冰开河而逐渐降低,经与南湾水文站实际观测的冰期持续时间相比较,其所得冰期持续时间与实测冰期持续时间变化一致,均略有延长趋势,这表明MOD09GQ能有效监测河冰物候信息;（2）开始封河时间与结束开河时间均有提前趋势,最早开始封河比最晚开始封河提前45天,最早结束开河比最晚结束开河时间提前31天,开始封河比结束开河提前时间更多,导致整个冰期持续时间有延长趋势;（3）封河速率有变慢趋势,开河速率有逐渐加快趋势,这意味着若未来该河段通航,每年通航期将延长,将带来更大的经济效益。 相似文献
16.
长江口北支的围垦使北支上、中段形成了河宽沿程变率较小的弯曲河槽,沿北支北岸的深槽水深条件得到改善,减弱了涌潮发生的条件,导致青龙港涌潮自2003年以来大为减弱。通过引进局部地形指数,建立了局部地形指数与青龙港平均涨率之间的良好相关关系。研究表明,青龙港平均涨率的年际变化与人类活动(围垦)在北支的进程以及青龙港附近的局部地形变化相应,并认为对于复式断面,采用全断面水力指标并不能很好地反映局部地形对涌潮的影响。由于长江口北支涌潮的近年变化将对长江南、北支分流点水域的河床演变产生重大影响,因此本研究对北支的航道整治和岸线开发利用具有现实意义。 相似文献
17.
典型岩溶区地下水系统重金属元素分布特征浅析——以广西坡月地下河为例 总被引：1，自引：0，他引：1
地下河为岩溶地下水系统的重要组成部分,为查清典型岩溶区地下水系统中重金属指标的含量变化及空间分布特征,文章以广西坡月地下河系统为例,通过不同断面两次采样分析,重点剖析地下河系统在水文地球化学作用下,地下水中以“五毒”元素及Zn、Al和Mn为代表的重金属元素含量。分析结果表明:坡月地下河水体pH值在7.34～8.10 之间,水体中“五毒”元素、Zn、 Al和Mn的检出含量极低或未检出,质量浓度均远小于国家地下水环境质量标准中的Ⅲ类水质标准,适合各种用途。检出含量较高的点主要为地下河明流段或补给区地表水,含量最高分布在坡心地下河出口水体,其原因是坡心地下河系统区内工矿企业和其它经济活动干扰相对较强,特别是工矿企业的矿石和尾矿渣的露天堆放（如金矿）是引起地下水中重金属元素的检出或超标的重要因素。 相似文献
18.
为预测黄河下游游荡性河道大规模整治后对河床演变的作用,基于河流动力学理论,通过物理模型试验的方法,以黄河下游游荡性河道典型河段为对象,研究了河床过程对河道整治的复杂响应关系。研究结果表明,河槽横断面形态的调整与人工边界约束程度、流量变差及含沙量变差有关;只要整治工程体系平面布设合理,整治工程量达到一定规模后,通过河道整治,可使河槽横断面形态趋于窄深方向发展,促使游荡型河道向限制性弯曲型河道转化,同时,河道泄洪输沙能力有所提高;河道整治后,不同河段的比降调整不会平行进行。 相似文献
19.
Flood is the worst weather-related hazard in Taiwan because of steep terrain and storm. The tropical storm often results in disastrous flash flood. To provide reliable forecast of water stages in rivers is indispensable for proper actions in the emergency response during flood. The river hydraulic model based on dynamic wave theory using an implicit finite-difference method is developed with river roughness updating for flash flood forecast. The artificial neural network (ANN) is employed to update the roughness of rivers in accordance with the observed river stages at each time-step of the flood routing process. Several typhoon events at Tamsui River are utilized to evaluate the accuracy of flood forecasting. The results present the adaptive n-values of roughness for river hydraulic model that can provide a better flow state for subsequent forecasting at significant locations and longitudinal profiles along rivers. 相似文献
20.
金沙江上游地质条件复杂,大型古堆积体群普遍发育,严重影响该区的水利水电开发建设。合理的解释古堆积体群的地质成因问题是进行水电建设工作的基础。本文以金沙江上游某水电站古堆积群现场工程为依托,通过工程地质分区、岩体结构特征分析和地质现象分析3个步骤,逐步还原了堆积体群的形成过程。最终结论如下: (1)以古堆积体群整体形貌特征为基础,结合岩性、结构等基本特性,将古堆积体群划分为4个区域; (2)根据古堆积群Ⅱ区的形貌特征假设Ⅱ区物质来自河对岸,继而采用结构特征分析证明了这一假设,结果表明: Ⅱ区物质与河对岸物质结构具有较好的一一对应关系,同时物质结构具有明显的分选性,为典型的泥石流产物; (3)结合区域风化程度、S型转弯、冲积扇、高位静水沉积等地质现象分析,还原了该古堆积体群的形成过程,即: Ⅰ区风化程度较严重,年代明显早于其他各区。Ⅲ区、Ⅳ区之间应为古河道,Ⅰ区的形成造成了河流的S形改道,但并未造成真正意义上的堵江。真正的堵江事件发生在Ⅱ区形成后。Ⅱ区泥石流物质与Ⅲ区、Ⅳ区物质一起形成了一个天然土石坝,形成了真正意义上的堵江,产生了高位沉积现象。此时江水一部分从古河道流出,一部分从Ⅱ区泥石流物质区向下渗流,最终Ⅱ区物质被掏蚀冲垮,形成了今河道。 相似文献