梯级水电开发对岷江上游径流特征的累积影响

发布时间：2018-08-27 12:47

【摘要】：河流梯级水电开发可以有效调节水资源的时空分布，是综合利用流域水能资源的最新趋势。但由于流域是一个关联度极高、整体性极强的系统，梯级水电开发在实现防洪、发电、灌溉等经济效益的同时，也将通过改变河流水文情势、影响径流年内年际分配特征等途径，引发流域内一系列累积性生态环境效应。本文以水电开发活动尤为强烈的岷江上游为研究区，探讨梯级水电开发对径流特征的累积影响。首先基于野外调查数据详细分析了岷江上游流域的水电开发特点，并对其水电开发程度进行定量评价；其次，选取杂谷脑河流域为典型子流域，基于桑坪水文站1956~2013年的月平均流量数据，运用数理统计、趋势分析等方法分析了杂谷脑河的径流年内分配特征、年际变化趋势和径流突变状况；再次，依据径流序列的年内年际变化特征与其主要影响因素如流域内气候变化特征、植被变化状况、水电开发时空格局等之间的相关关系，，确定出不同时期影响杂谷脑河径流演变的主导性因素；最后，以水电开发为主要影响因素的时期为重点研究时段，分析了水电站在单点式运行、无“龙头水库”调节的梯级运行和有“龙头水库”调节的梯级运行等运行模式下的径流变化特征，分析不同水电开发模式对径流特征的影响状况，初步探索了梯级水电开发对径流演变的影响机制。得出的主要结论如下：（1）岷江上游水电站类型以高水头低闸坝的引水式小水电为主，径流式水电站多，调节式水电站少。引水式水电站的渠首类型以低闸引水式、底格栏栅式和滚水坝式为主，高坝大库相对较少。水电开发的高潮集中于2000~2010年，水电开发活动已拓展至岷江三级支流。（2）构建了水电开发率、水电开发密度和水电开发强度3个指标，用于综合评价流域（或区域）的水电开发程度。该方法不仅避免了目前单一评价指标难以体现流域水电开发空间差异的缺陷，也可以用来辅助量化某些缺乏水能资源理论蕴藏量数据的河流水电开发程度。结果表明，岷江上游流域的水电开发率为74%，远高于全国平均水平（34%），梯级水电开发强度大于国内主要河流。干流不同河段中，汶川至都江堰河段的水电开发程度最高；一级支流中，杂谷脑河的水电开发率达99%，水电开发密度0.56，流域水电开发强度0.17，成为岷江上游水电开发程度最高的区域。（3）近60年来杂谷脑河流域的径流量呈显著减少趋势。年径流量变化主要经历了2个阶段，即1956~1965年、1971~1991年的增加阶段和1966~1970年、1992~2013年的减少阶段，在1992年发生了径流突变。从径流年内分配特征上看，径流年内分配的不均匀性呈减小趋势，其中2000~2013年的不均匀性降至最低；集中程度上，1970~1979年和2000~2013年两时段的集中度最小，并且两时段的最大径流出现时间均表现为明显提前；径流年内分配变化幅度在2000年之前呈减小趋势，在2000~2013年间略有增大。（4）20世纪50年代中期~80年代初、80年代中期~90年代中期和2000~2013年三时期影响杂谷脑河径流过程的主导性因素分别为森林植被变化、气候变化和水电开发活动。对年径流量和月平均径流量的突变检验结果表明，气候变化因素导致了年径流量的突变，植被变化因素导致了月径流量突变，迄今为止尚未观测到由水电开发活动引致的年/月时间尺度的径流突变现象。（5）2000年至今高强度的水电开发活动对河川径流的年内分配特征产生了显著影响。单点式水电运行模式减小了径流年内分配的不均匀程度和集中程度，并使最大径流出现的时间明显提前。这可能是由于引水式水电站的引水渠道（或隧洞）具有类似于天然河流裁弯取直的水文效应，即加快洪水的排泄速度而引起。无“龙头水库”调节的梯级水电群对径流的年内分配特征产生了较为明显的累积效应，表现为明显降低径流年内分配的不均匀程度、集中程度和变化幅度，并使最大径流的发生时间略微延迟，表明由多个具备日调节能力的水电站组成的梯级水电群对洪峰具有一定的调节能力。有“龙头水库”调节的梯级水电群使河川径流的年内分配不均匀性和集中程度降至最低，其对径流年内分配特征的影响程度远超过其他水电运行模式，表现出了更为明显的累积效应。（6）年际时间尺度上的径流演变特征主要受气候变化和植被恢复因素控制，水电开发活动的影响并不明显。月时间尺度上，单点式水电站运行对各月径流量总体上影响不显著，仅改变了极少数月份的径流状况。无“龙头水库”调节的梯级水电群运行对径流过程的改变程度较大，由多个具备日调节能力水库构成的梯级水库群，由于累积效应的作用，其对径流的调节能力具有类似于月调节能力水库的调节效果。有“龙头水库”调节的梯级水电群使历史上的最大径流月份由6月延后至7月，对径流的削峰补枯调节能力比单一水库更加显著。
[Abstract]:River cascade hydropower development can effectively regulate the temporal and spatial distribution of water resources and is the latest trend of comprehensive utilization of river basin hydropower resources.However, because river basin is a highly correlated and integrated system, cascade hydropower development will not only achieve economic benefits such as flood control, power generation and irrigation, but also influence the river diameter by changing the hydrological situation. The interannual distribution characteristics of the annual runoff cause a series of cumulative eco-environmental effects in the basin.
This paper takes the upper reaches of Minjiang River as the study area, and discusses the cumulative effect of cascade hydropower development on runoff characteristics. Firstly, based on field survey data, the characteristics of hydropower development in the upper reaches of Minjiang River are analyzed in detail, and the degree of hydropower development is evaluated quantitatively. Secondly, Zagunao River Basin is selected as a typical example. Based on the monthly average discharge data of Sangping Hydrological Station from 1956 to 2013, the annual distribution characteristics, interannual variation trend and abrupt change of runoff in Zagunao River are analyzed by using mathematical statistics and trend analysis methods. Thirdly, the interannual variation characteristics of runoff series and its main influencing factors, such as the characteristics of climate change in the basin, are analyzed. The main factors affecting the runoff evolution of Zagunao River in different periods are determined by the correlation among the characteristics of vegetation, the spatial-temporal pattern of hydropower development, etc. Finally, the single-point operation of hydropower stations and the cascade operation without "leading reservoir" regulation are analyzed with the period of hydropower development as the main influencing factor. The runoff variation characteristics under the operation modes such as the cascade operation with the regulation of the "Dragon Head Reservoir" are analyzed. The influence of different hydropower development modes on the runoff characteristics is analyzed. The influence mechanism of the cascade hydropower development on the runoff evolution is preliminarily explored.
(1) The main types of hydropower stations in the upper reaches of Minjiang River are diversion-type small hydropower stations with high head and low gate dams, more runoff-type hydropower stations and less regulation-type hydropower stations. It has been extended to the three tributaries of Minjiang River.
(2) Three indexes, namely, hydropower development rate, hydropower development density and hydropower development intensity, are constructed to evaluate the degree of hydropower development in a river basin (or region). The method not only avoids the defect that single evaluation index is difficult to reflect the spatial difference of hydropower development in a river basin, but also can be used to quantify the theoretical implications of the lack of hydropower resources. The results show that the hydropower development rate of the upper reaches of the Minjiang River is 74%, much higher than the national average (34%), and the cascade hydropower development intensity is higher than that of the main rivers in China. The area with the highest degree of hydropower development in the upper reaches of Minjiang River is 99%, the density of hydropower development is 0.56, and the intensity of hydropower development in the basin is 0.17.
(3) In the past 60 years, the runoff of Zagunao River Basin has been decreasing significantly. The annual runoff changes have mainly experienced two stages: 1956-1965, 1971-1991 increasing stage and 1966-1970, 1992-2013 decreasing stage. Runoff abrupt change occurred in 1992. Among them, the non-uniformity of 2000-2013 was the lowest; the concentration degree was the smallest in 1970-1979 and 2000-2013, and the time of maximum runoff appeared in both periods was significantly earlier; the annual distribution of runoff decreased before 2000 and increased slightly in 2000-2013.
(4) From the mid-1950s to the early 1980s, from the mid-1980s to the mid-1990s and from 2000 to 2013, the dominant factors affecting the runoff process of Zagunao River were forest vegetation change, climate change and hydroelectric development activities, respectively. The abrupt change of runoff and vegetation causes the abrupt change of monthly runoff. So far, no abrupt change of annual/monthly runoff caused by hydropower development has been observed.
(5) High-intensity hydropower development activities from 2000 to now have a significant impact on the annual distribution characteristics of river runoff. The single-point hydropower operation mode reduces the uneven distribution and concentration of runoff in a year, and makes the time of maximum runoff appear significantly earlier. This may be due to the diversion channel (or tunnel) of the diversion hydropower station. (2) It has a hydrological effect similar to natural river bending, i.e. accelerating flood discharge rate. The cascade hydropower group without "dragon head reservoir" regulation has a more obvious cumulative effect on the annual distribution characteristics of runoff, showing a significant reduction in the unevenness, concentration and variation of runoff distribution during the year, and The occurrence time of maximum runoff is slightly delayed, which indicates that the cascade hydropower group composed of several hydropower stations with daily regulating capacity has certain regulating ability to flood peak. The degree of impact is far greater than that of other hydropower operation modes, showing a more obvious cumulative effect.
(6) The characteristics of runoff evolution on the interannual time scale are mainly controlled by climate change and vegetation restoration factors, and the impact of hydropower development is not obvious. On the monthly time scale, the operation of single-point hydropower station has no significant effect on the monthly runoff, but only changes the runoff situation in a few months. The runoff process is greatly changed by the operation of hydropower groups. The cascade reservoirs consisting of several reservoirs with daily regulating capacity have similar regulating effect to the monthly regulating capacity reservoirs due to the cumulative effect. The cascade hydropower groups with "dragon head reservoir" regulation make the largest runoff month in history. From June to July, the ability to peak and fill up runoff is more significant than that of a single reservoir.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV72;TV121

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