寒冷区明渠冬季输水结冰是常见的自然现象。南水北调中线工程水面一旦形成冰盖其安全输水流量仅为设计流量的30%~50%,而气温是驱动冰盖形成的主要因子,如何科学评价冬季气温等级是冰期输水面临的关键问题之一。分析了沿线8座气象站1951—2021年冬季日平均气温和日最低气温数据,揭示了总干渠气温沿程和年际变化规律。基于拉格朗日质点跟踪法,结合沿线气温-水温-冰盖生成物理过程,提出了气温链概念并给出通用数学表达式。分别采用国标法、一月平均气温法和气温链法评价冬季气温等级,构建了71 a冬季气温位次。结果表明:①总干渠自南向北气温逐级下降速率为0.48 ℃/(100 km),保定站呈加速下降趋势,对冰盖生成贡献最大。②沿线冬季气温总体呈波动上升趋势,升温速率为0.37 ℃/(10 a),强暖冬出现在最近30 a,强冷冬出现在前30 a,气温的总体上升有利于减缓大范围冰盖生成。③对于冰盖生成预测,气温链法优于一月平均气温法,更优于国标法;不同时间尺度组合评价可获得更优的结果;全球持续变暖背景下,可采用一月平均气温法和北方2站6 d气温链法联合评价。④给出了北方2站6 d气温链法冬季等级的分界阈值,即强暖冬T_C≥-4.0 ℃,弱暖冬-5.7 ℃≤T_C<-4.0 ℃,正常-7.4 ℃<T_C<-5.7 ℃,弱冷冬-9.1 ℃<T_C≤-7.4 ℃,强冷冬T_C≤-9.1 ℃,长系列均值为-6.5 ℃。研究成果可更好地为南水北调中线工程总干渠冰盖生成提供新的参考基准。

The freezing of water-conveying open channel in winter is a common natural phenomenon in cold regions. Once ice carapace appears in the middle route of the South-to-North Water Transfer Project, the safe flow reduces to only 30%-50% of the design flow. As temperature is the main factor driving the formation of ice carapace, the evaluation of air temperature level in winter became a key problem for water conveyance in freezing period. The interannual variations of air temperature along the main canal is revealed according to the daily average temperature and daily minimum temperature data of eight meteorological stations along the line of the Project in winter from 1951 to 2021. A concept of air temperature chain is proposed and the general mathematical expression is given based on the Lagrange particle tracking method in line with the physical process of air temperature affecting water temperature and then further producing ice carapace along the line. The National Standard Method, January’s Average Temperature Method, and the proposed Air Temperature Chain Method are used to evaluate the winter temperature level and construct the temperature order in 71 years. Results manifest that: 1) The air temperature along the main canal decreased gradually from south to north at a rate of 0.48 ℃/(100 km), and in particular, Baoding station displayed an accelerated downward trend, which made the greatest contribution to the formation of ice carapace. 2) The temperature in winter was fluctuating upwardly in general at a rate of 0.37 ℃/10 a. Severe warm winter appeared in the recent three decades and severe cold winter in the first three decades. The rising of air temperature is conducive to alleviating the formation of large-scale ice carappace. 3) The proposed Air Temperature Chain Method is superior to the January’s Average Temperature Method and the National Standard Method in predicting the formation of ice carapace. Better prediction result can be achieved by combining different time scales. Under the background of continuous global warming, the joint evaluation by January’s Average Temperature Method and Air Temperature Chain Method with 6-day data at two north stations can be adopted. 4) The thresholds of winter temperature grade obtained by the Air Temperature Chain Method with 6-day data at two north stations are given as follows. Strong warm winter: <i>T</i>_C≥-4.0 ℃; weak warm winter: -5.7 ℃≤<i>T</i>_C＜-4.0 ℃; normal winter: -7.4 ℃＜<i>T</i>_C＜-5.7 ℃; weak cold winter: -9.1 ℃＜<i>T</i>_C≤-7.4 ℃; strong cold winter: <i>T</i>_C≤-9.1 ℃. The average value of long series <i>T</i>_C is -6.5 ℃. The research finding is expected to offer a new reference for predicting the formation of ice carapace in the main canal.

The mid-route of South-to-North Water Diversion Project has many control buildings and complex geological conditions as well as quite different geographical and meteorological conditions along the long line. The design, construction and operation of the project is faced with many technically difficult hydraulics problems. Through decades of research, the Yangtze River Scientific Research Institute has obtained fruitful research results, some of which were applied to the project successfully. In this paper, we expound and summarize several major achievements including canal roughness issues, sluice discharge formula, type of the yellow river crossing tunnel and its hydraulic characteristics, emergency dispatch, and water diversion in winter. It provides technical support for the operation of the middle route and also could be regarded as reference for the design of similar projects.

为了掌握临沂市冬季气候特征及其冷暖冬的成因，减少冷暖冬对农业生产的不利影响，以便更有效利用冬季气候资源服务于临沂地区农业生产，利用临沂市1961—2011 年12—2 月气温观测资料，采用统计方法进行气候诊断研究，分析了临沂市近51 年冬季平均气温的变化趋势，在此基础上，依据中国国家标准《暖冬等级》，参照单站、区域暖冬等级标准，确定了单站和区域冷冬等级，统计分析了1961—2011 年临沂10 个站冷、暖冬事件的气候变化特征。结果表明：近51 年临沂各地冬季平均气温呈明显升高趋势，尤其是在20 世纪90 年代以后表现更为明显。临沂单站和区域暖冬指数均呈显著上升趋势，51年区域暖冬事件共发生10 次，强暖冬3 次，主要出现在20 世纪90 年代以后。各站冷冬事件发生频率为47%~59%，强冷冬频率为20%~31%。区域冷冬指数呈-17.7%/10 a 的显著下降趋势，区域冷冬事件共发生27 次，其中强冷冬14 次，主要出现在20 世纪80 年代以前，20 世纪90 年代以后显著减少，与暖冬成相反的变化趋势。冷暖冬的成因主要归咎于温室效应、东亚冬季风、西太平洋副热带高压、ESNO等因素，其中最重要、最直接的原因取决于南下冷空气的强度和频率，冷空气强且频，其冬必冷，冷空气强度小、频率低，则易出现暖冬。

In order to grasp the climatic characteristics and causes of cold and warm winter over Linyi City, based on the 12 to 2 monthly average temperature data in Linyi from 1961 to 2011, using the statistical methods to climate diagnostic studies, the variation trend of winter mean temperature over Linyi during recent 51 years was analyzed, on this basis, according to the China national standard warm winter grade and referring to single station and regional warm winter grade standards, the grade of single station and regional cold winter were determined. On the basis of the division method for cold and warm winter, the author analyzed theclimatic change events of 10 stations’cold and warm winter in Linyi from 1961 to 2011. The results showed that: the trend of average temperature in winter increased significantly over Linyi, especially more obvious since the 1990s. Both IWs and IWa showed a significant upward trend, there were 10 regional warm winter years over the 51 years with 3 strong warm winter, and mainly after the 1990s, the frequency of single cold winter was 47%-59% with 20%-31% of strong cold winters, and ICd showed a significant decreasing trend at a decadal rate of -17.7%. There were 27 regional cold winter years over the 51 years with 14 strong cold winters, and mainly before the 1980s, significantly reduced after 1990s. The main factors of cold and warm winter attributed to the greenhouse effect, the weaken east Asian winter monsoon, the strengthened subtropical high in the western Pacific, ESNO etc, one of the most important and direct reason depended on the intensity and frequency of cold air, strong and frequent cold air, it would be a cold winter, and weak and low frequency was prone to warm winter.

根据玛纳斯河流域上游肯斯瓦特水文站1959—2008年气温、降水量及1984—2000年蒸发量观测资料,运用线性回归、Pearson相关系数、5 a滑动平均、Mann-Kendall检验以及Morlet小波分析方法对流域上游气候变化特征进行分析。结果表明①近50 a玛纳斯河流域上游气候总体趋向于暖湿,其中年均气温显著升高,且年内气温变化存在明显的季节差异,夏、秋两季增温趋势显著,降水量总体也呈增加趋势,但不够显著,且年内分配不均匀,降水量主要集中在春、夏两季;②近20 a流域年蒸发量围绕均值1 651.2 mm上下波动,总体呈微小增加趋势;③气温和降水量在20世纪90年代期间发生由低向高的突变,并且存在明显的年际周期变化。

According to observed data of temperature, precipitation series (1959-2008) and evaporation series (1984-2000) at Kensiwate hydrological gauging station in the upstream of Manas River Basin. We analysed the climate change in this region by using linear regression, Pearson correlation coefficient, moving average for five years, Mann-Kendall nonparametric statistical test and Morlet wavelet analysis method. Results showed that 1) the climate of upstream Manas River Basin was mostly warm and wet in the past 5 decades. The annual average temperature increased remarkably with obvious seasonal difference within the year (temperature increased in summer and autumn). Precipitation was increasing as a whole but was not significant, and distributed unevenly within the year (precipitation concentrated in spring and summer); 2) The annual evaporation fluctuated around 1651.2 mm in the recent two decades, displaying a trend of slight increase; 3) Temperature and precipitation increased abruptly from low level to high level during the 1990s, and there was an obvious inter-annual cycle change.

根据北京市1951年-2010年的降水和气温数据资料, 综合运用滑动平均法、Mann-Kendall检验、Hurst指数法、GM(1, 1)模型等方法, 从不同时间尺度和层面上分析北京市降水和气温变化的规律以及未来的趋势特征。结果表明:北京市降水的72.5%集中在夏季, 7月份的降水最多, 12月份最少;极端降水指标中的1日最大降水量、极端强降水日数、极端强降水比率、最长连续无降水天数呈不同程度的递减趋势, 零降水日数以2d/10a的速率递增;北京市历年的降水量以44.3mm/10a的速率递减, 1994年为降水的突变年份, 未来的降水整体上呈增加趋势, 北京市下一次旱灾大致指向2028年-2029年左右;北京市历年的平均气温、平均最高气温和平均最低气温呈不同程度的增加趋势, 平均最低气温的增加趋势最为显著, 平均气温和平均最低气温的突变年份都是1989年, 而平均最高气温的突变年份为1993年-1994年和1996年, 三者未来整体上都呈增加趋势, 而平均最低气温的增加趋势最为显著。

With data of precipitation and temperature of Beijing city during 1951-2010, this paper has analyzed and researched their regular rules and future trend from different time scales and levels. Several comprehensive methods have been applied, such as sliding average method, Mann-Kendall test method, Hurst index method, GM(1, 1)model and so on. The main results of this research are as follows: the average precipitation of Beijing city is about 588.1mm in the past 60 years; the percent of precipitation concentrated in summer is about 72.5% in Beijing city, the month with the most precipitation is July and the least is December; among the extreme precipitation index, one-day maximum precipitation, extreme rainfall days, extreme rainfall ratio and the longest continuous days without precipitation present diminishing trend with different degrees, while the days without precipitation present increasing trend with a ratio of 2d/10a; the precipitation of Beijing has been reducing by 44.3mm/10a over the years, and the year of mutation of precipitation is 1994, the precipitation of which is 813.2mm; the hurst index of Beijing is less than 0.5, so the future precipitation of Beijing will present a trend of increase on the whole, meanwhile, the next drought year is pointed to 2028-2029; the average temperature, average highest temperature and average lowest temperature of Beijing have risen with different degrees over the years, the amplitude of the average highest temperature is the least while the increasing trend of average lowest temperature is most significant with an increasing ratio of about 0.5℃/10a; the mutation year of average temperature and average lowest temperature is 1989, and that of average highest temperature is 1993-1994 and 1996. All these three temperatures will rise in the future, and the increasing trend of average lowest temperature is the most obvious. The above research results can provide scientific and theoretic basis for the future deep research of Beijing city and other regions. It also benefits for the management of urban water resources and climate warming.

为了给多沙水库运行调度提供依据,降低水沙序列长度和随机性的影响,将小波变换应用于研究流域径流与含沙量的变化特性。采用db3小波对标准化径流与含沙量序列进行多分辨率分析,研究径流与含沙量变化的趋势性;选用复Morlet小波绘制出小波方差图,分析径流过程与含沙量过程存在的周期性。以崖羊山水电站所在的李仙江流域为例,针对电站坝址断面的月平均流量与含沙量序列进行小波分析,从低频重构序列的结果中可以看出该流域径流与含沙量的变化趋势;并结合当地的降雨量与水土保持状况分析,表明结果是合理的。根据小波方差图可以看出,崖羊山水电站所在流域径流过程与含沙量过程存在非常接近的显著周期,均为2 a左右,且两者变化周期具有同步性。研究结果表明小波分析是研究非平稳随机时间序列的有效方法。

In the aim of providing basis for the operation of sandy reservoir and reducing the influences of length and randomness of flow and sediment series, wavelet transform was adopted to analyze the variation characteristics of flow and sediment series. Standardized monthly flow and sediment series were decomposed by Multi-resolution Analysis using the db3 wavelet function, and continuous wavelet transform was used to evaluate the periodic variations of the two standardized series using the complex valued Morlet function. The flow and sediment series at the dam site of Yayangshan Hydropower Station located in Lixianjiang watershed were taken as an example. The reconstruction of the lowest frequency part revealed the trend of the flow and sediment series. According to the local rainfall and soil and water conservation, the result is considered reasonable. Wavelet variances were obtained to identify the dominant period as 2-year approximately for both flow series and sediment series and reveal the synchronization between them. The results indicate that wavelet transform is effective for nonstationary stochastic series analysis.