中长期径流预报的一种灰关联模式识别与预测方法

基于时间序列多重信息利用的扩维原理和灰色系统理论的关联分析思想,提出一种应用于水文中长期预报的方法.它的特点是直接从径流序列的扩维相型关联分析中,寻求径流情势变化规律,较适合于缺乏输入因子资料或选择影响因子有困难条件下的水文中长期预报.利用海河、黄河和长江流域若干水文站的实测资料序列对该方法做了初步验证.     

额尔古纳河流域近50年水文气象要素变化分析

应用预置白处理后的Mann—Kendall非参数检验方法及小波分析方法,分析了额尔古纳河流域20个水文气象站点近50年水文气象要素(气温、降水和径流)的变化趋势以及典型站点降雨量、径流量的多时间尺度特征。同时应用聚类分析方法推算了径流量序列的突变点。结果表明,该区域气温呈现明显升高的趋势,其中海拉尔站可能由于城市化进程的影响气温升高幅度最大。流域年降水总量变化趋势不显著,但某些月份降水量存在明显增加或者减小的趋势,其中显著增加的月份为11、12和1月,显著减小的月份为7、8月;降水趋势显著变化的站点主要分布在该流域的呼伦湖水系和海拉尔河水系。流域年径流量有减少趋势但不显著,然而4、5月份大多数站点径流量出现显著减少趋势。小波分析表明,典型站点年降水量存在25a左右的主周期,年径流量存在20～26a的主周期。各个站点径流量序列的显著跳跃点大都发生在1999年,这与通过小波分析得出的有关突变点的结论相一致。     

水文时间序列趋势和跳跃分析的再抽样方法研究

用再抽样方法估计水文时间序列趋势或跳跃的显著性水平,可通过分块的方法消除水文时间序列自相关性的干扰,具有直接、精确的优点。介绍了再抽样方法在水文时间序列趋势和跳跃分析中的原理与方法;针对黄河三门峡水文站1919～1989年实测年径流量资料,采用几种常用的参数和非参数统计量,用再抽样方法进行了实例研究,其中采用滑动分块自助法以消除自相关性的干扰,该方法为估计水文时间序列的趋势、跳跃的显著性水平给出了新的思路与途径。     

孤山川流域降水变化特征及趋势分析

依据孤山川流域1956—2006年逐月实测降水资料,采用Mann-Kendall检验法、五点滑动平均法、R/S分析法等方法对孤山川降水进行分析。结果表明:孤山川流域降水主要集中于7、8、9三个月,年内分配极不均匀;降水序列存在明显减少趋势,且季降水序列分别存在着不同的变化趋势,夏季有明显减少趋势,冬季相反有增加趋势,春秋二季减少趋势不显著;经Mann-Kendall检验法、R/S分析表明孤山川流域降水减少趋势有持续性。     

An improved version of innovative trend analyses

Systematic and random changes occur in any hydro-meteorological record and have significant effects on human activities on time and space scales. Although it is almost impossible to forecast the future behavior of any natural event accurately, researchers can identify trend on systematic variations and seasonality rather accurately with random residual parts. On the other hand, the role of trend is very significant in climate change studies and the Mann-Kendall test is the most employed method for trend identification. However, this method requires restrictive assumptions such as the data length, normality, and serial independence. Recently, innovative trend analysis (ITA) method is suggested for detailed trend determination and classification interpretations in a given time series without restrictive assumptions. In this study, an ITA-change boxes (CB) approach is proposed, taking into account quantitative changes with increasing or decreasing trends of the two half-time series obtained from the data. Given the periodicity of the hydro-meteorological data, the data group is used to obtain two half-time series instead of the data. This allows the researcher to numerically observe changes in trends beyond visualization. This approach assists to make more detailed interpretations about trend possibilities within a given time series. The applications of the proposed approach are presented for daily temperature and monthly rainfall and discharge records from Turkey, UK, and the USA.     

大凌河流域上游水资源变化趋势及成因研究

R/S和Mann-Kendall都是用来研究径流和降雨变化的常用方法,R/S方法可以揭示序列的水文特征和变异点,但不能说明研究对象未来的变化趋势;Mann-Kendall可以检验水文序列趋势和变化的程度,但不能预测水文时间序列未来的趋势特征。针对R/S和Mann-Kendall法在水文变化趋势分析中的优点和不足,提出了二者相结合的水文变化趋势特征分析,并将其应用于大凌河流域上游的水资源变化趋势分析中。研究表明,R/S和Mann-Kendall综合分析法较好地揭示了降水和径流的变异点,也揭示出降水变化趋势不明显,径流呈现较为显著的下降趋势。本文对径流和降水不对称的相应关系及其成因进行了分析,得出流域内大量的水利工程截留和人类活动取用水成为径流显著下降的主要驱动因素。     

基于中国气象资料的趋势检验方法对比分析

结合全国317个气象站1956-2005年气象资料,分别利用普通Mann-Kendall、预置白Mann-Kendall、去趋势预置白Mann-Kendall趋势检验方法分析了年降水量、年平均气温和年蒸发皿蒸发量的趋势检验结果及自相关系数变化规律。其中,年降雨序列的自相关性不显著,3种趋势检验方法的分析结果差异不大;年平均气温和年蒸发皿蒸发量自相关性显著,其3种方法的检验结果差异性较大,需要剔除自相关性后进行趋势检验;空间特征上,北方站点气象要素的自相关显著性较高。数据分析和数学推导表明,序列正自相关性会放大序列趋势的显著性,序列的趋势项会增大计算的自相关系数。     

西藏参考作物蒸发蒸腾量的时空变异规律

根据西藏高原区38个气象站点自建站到2006年的逐日气象观测资料,利用FAO-56标准Penman-Monteith公式计算各站逐日参考作物蒸发蒸腾量(ET₀)。重点分析了7个站点逐日、逐月ET₀年内变化规律,采用Mann-Kendall法对其月际和年际ET₀进行趋势检验;利用Kriging插值及Surfer8.0空间分析功能,得到西藏高原区年ET₀均值的等值线图,分析了全区年ET₀均值的空间分布特征。结果表明:昌都、林芝和那曲的逐日ET₀在年内变化曲线基本一致,呈现单峰抛物线形状,拉萨、泽当和日喀则的逐日ET₀年内变化趋势基本一致,6～9月变化曲线呈现较快的下降趋势,狮泉河的ET₀呈现单独变化趋势;所有站点的逐月ET₀年内变化规律与逐日ET₀相同,最大值均出现在6月份,最小值出现在12月份;日喀则各月及干湿季ET₀的Mann-Kendall检验大多呈现显著的降低趋势,其次是泽当,呈现增加趋势较多的是林芝;全系列年ET₀均值Mann-Kendall检验呈现降低趋势的站点偏多;西藏高原区年ET₀均值具有东部和中南部高,东北部和东南缘低的空间分布规律。     

Spatio-temporal analysis of recent groundwater-level trends in the Red River Delta, Vietnam

A groundwater-monitoring network has been in operation in the Red River Delta, Vietnam, since 1995. Trends in groundwater level (1995?C2009) in 57 wells in the Holocene unconfined aquifer and 63 wells in the Pleistocene confined aquifer were determined by applying the non-parametric Mann-Kendall trend test and Sen??s slope estimator. At each well, 17 time series (e.g. annual, seasonal, monthly), computed from the original data, were analyzed. Analysis of the annual groundwater-level means revealed that 35?% of the wells in the unconfined aquifer showed downward trends, while about 21?% showed upward trends. On the other hand, confined-aquifer groundwater levels experienced downward trends in almost all locations. Spatial distributions of trends indicated that the strongly declining trends (>0.3?m/year) were mainly found in urban areas around Hanoi where there is intensive abstraction of groundwater. Although the trend results for most of the 17 time series at a given well were quite similar, different trend patterns were detected in several. The findings reflect unsustainable groundwater development and the importance of maintaining groundwater monitoring and a database in the Delta, particularly in urban areas.     

Long karst spring discharge time series and droughts occurrence in Southern Italy

A series of long karst spring discharges have been analysed to determine trends, fluctuations and relationship to rainfall. Data come from aquifers in southern Italy, and in some cases cover more than one hundred years of records. Based on yearly discharge data, hydrological series show the drop of the discharge after 1986, which has been interrupted by the recent wet years of 2009 and 2010. This drop is connected to the decrease in annual rainfall, but other factors also seem to contribute to this phenomenon. Based on monthly scale data series, the relationship between meteorological and hydrological droughts has been analyzed, using the standard precipitation index (SPI). As karst systems are large reservoirs, only longer meteorological droughts induce groundwater droughts, and the start, duration and time-lag of the hydrological droughts have been evaluated.     

Climate change impact on rainfall spatio-temporal variability (Macta watershed case,Algeria)

This work describes the climate change impact study on rainfall patterns in Macta watershed, located in the northwest of Algeria. The monthly rainfall data collection, verification and validation have built a database with 42 stations, each with 42 years of observations from 1970 to 2011. The study of annual total rainfall has identified a downward trend and quantifies the deficits that are within the observation time series. The division of the annual rainfall series into four periods allowed to highlighting the increase in inter-year temporal variability with the coefficient of variation increases from 17 to 27%. The study shows an annual rainfall deficit increment from 13 to 25%. The standard deviation values decrease significantly for the last two periods showing a spatial variability. Multivariate statistical study by the hierarchical clustering method resulted in the formation of station groups indicating the unification of monthly rainfall patterns.     

Trend analysis of rainfall pattern over the Central India during 1901–2010

In the present study, trends of rainfall of the Central India were evaluated in monthly, seasonal, and annual time scales using the Revised Mann-Kendall (RMK) test, Sen’s slope estimator, and innovative trend method (ITM). For this purpose, the monthly rainfall data for 20 stations in Madhya Pradesh (MP) and Chhattisgarh (CG) states in Central India during 1901–2010 was used. The Sen’s slope estimator was utilized for calculating the slope of rainfall trend line. Based on the obtained results of RMK test, there is no significant trend in the stations for the January and October months. The results also showed that for MP, two out of 15 considered stations indicate significant annual trend, while the CG has four out of five stations with significant trend. The results of applying ITM test indicated that most of the stations have decreasing trends in annual (16 stations), summer (16 stations), and monsoon (11 stations) seasons, while the winter (12 stations) and post monsoon (11 stations) seasons generally show increasing trend. Unlike the RMK, the ITM shows significant increasing trend in rainfall of November and December months. The finding of current study can be used for irrigation and water resource management purpose over the Central India.     

Impact of Rainfall Variability on River Hydrology: A Case Study of Southern Western Ghats,India

The Western Ghats plays a pivotal role in determining the hydrological and hydroclimatic regime of Peninsular India. The mountainous catchments of the Ghats are the primary contributors of flow in the rivers that sustains the life and agricultural productivity in the area. Although many studies have been conducted in the past decades to understand long term trends in the meteorological and hydrological variables of major river basins, not much attention have been made to unfold the relationship existing among rainfall and river hydrology of natural drainages on either side of the Western Ghats which host one of the unique biodiversity hotspots across the world. Therefore, an attempt has been made in this paper to examine the short term (last three decades) changes in the rainfall pattern and its influence on the hydrological characteristics of some of the important rivers draining the southern Western Ghats as a case study. The short term, annual and seasonal trends in the rainfall, and its variability and discharge were analyzed using Mann-Kendall test and Sen’s estimator of slope. The study showed a decreasing trend in rainfall in the southwest monsoon while a reverse trend is noticed in northeast monsoon. Correspondingly, the discharge of the west and east flowing rivers also showed a declining trend in the southwest monsoon season. The runoff coefficient also followed the trends in the discharge. The runoff coefficient of the Periyar river showed a decreasing trend, whereas the Cauvery river exhibited an increasing trend. A high-resolution analysis of rainfall data revealed that the number of moderate rainfall events showed a decreasing trend throughout the southern Western Ghats, whereas the high intensity rainfall events showed an opposite trend. The decline in groundwater level in the areas which recorded an increase in high intensity rainfall events and decrease in moderate rainfall events showed that the groundwater recharge process is significantly affected by changes in the rainfall pattern of the area.     

Trend estimation and univariate forecast of the sunspot numbers: Development and comparison of ARMA, ARIMA and Autoregressive Neural Network models

In the present study, a prominent 11-year cycle, supported by the pattern of the autocorrelation function and measures of Euclidean distances, in the mean annual sunspot number time series has been observed by considering the sunspot series for the duration of 1749 to 2007. The trend in the yearly sunspot series, which is found to be non-normally distributed, is examined through the Mann-Kendall non-parametric test. A statistically significant increasing trend is observed in the sunspot series in annual duration. The results indicate that the performance of the autoregressive neural network-based model is much better than the autoregressive moving average and autoregressive integrated moving average-based models for the univariate forecast of the yearly mean sunspot numbers.     

长江源区1956-2000年径流量变化分析

利用Mann-Kendall趋势检验法对长江源区直门达水文站的资料进行分析,揭示长江源区年径流量在1956-2000年间呈微弱的减少趋势。结合流域气象资料分析,该时段流域内升温明显,最大可能蒸发量呈增加趋势,降水也呈微弱减少趋势。径流变化与降水变化基本一致,降雨-径流关系没有发生明显变化,表明1980-2000年降水量减少是该时段径流量减少的直接原因,温度升高有利于融冰融雪和降水形式的变化,但由于融冰融雪占径流补给的比率相对较小,该时段温度升高导致融冰融雪的增加不足以抵消降水量的减少对径流的影响。径流量季节变化分析,揭示长江源区春季径流呈增加的趋势,这可能与融雪过程提前以及融雪量增加有关。     

Effect of climate change on the trends of evaporation of phreatic water from bare soil in Huaibei Plain,China

When the soil condition and depth to water table stay constant, climate condition will then be the only determinant of evaporation intensity of phreatic water from bare soil. Based on a series of long-term quality-controlled data collected at the Wudaogou Hydrological Experiment Station in the Huaibei Plain, Anhui, China, the variation trends of the evaporation rate of phreatic water from bare soil were studied through the Mann-Kendall trend test and the linear regression trend test, followed by the study on the responses of evaporation to climate change. Results indicated that in the Huaibei Plain during 1991-2008, evaporation of phreatic water from bare soil tended to increase at a rate of 5% on monthly scale in March, June and July while in other months the increase was minor. On the seasonal basis, the evaporation saw significant increase in spring and summer. In addition, annual evaporation tended to grow evidently over time. When air temperature rises by 1 °C, the annual evaporation rate increases by 7.24–14.21%, while when the vapor pressure deficit rises by 10%, it changes from-0.09 to 5.40%. The study also provides references for further understanding of the trends and responses of regional evapotranspiration to climate change.     

小波分析在水文学中的应用研究及展望

扼要介绍了20世纪80年代初发展起来的,被誉为数学“显微镜”的信号分析新方法——小波分析。在此基础上,综述了小波分析在水文水资源系统中的应用研究现状。展望了小波分析在该领域的未来研究趋势和发展方向。将小波分析引入水科学,不但拓宽了应用范围,而且推动了小波理论本身的发展。     

哈密地区平原区与山区气候变化差异性分析

利用水文气象站点数据采用线性趋势分析法和Mann-kendall检验法分析了哈密地区与水资源息息相关的山区与平原区气候要素变化的差异性。结果表明：山区与平原区实测站点气候要素多年平均月系列变化规律与趋势基本一致,在量上存在一定的差异;气象站点与水文站点降水要素均呈波动增加的趋势,总体不明显,山区与平原无明显的差别,相对以头道沟站降水增加较明显;气温均呈波动升高的趋势,并且受所处的地理位置影响较大,在相近经度方向上山区气温的升高幅度高于平原区;哈密气象站与头道沟水文站点降水以上世纪70年代增幅最明显,而伊吾气象站和苇子峡水文站以上世纪80-90年代降水增幅最明显;气温除伊吾气象站上世纪90年代升温明显外,其他各站点均以70-80年代升温最明显。     

长江源区径流量变化分析

利用1960~2012年长江源区直门达以上流域水文观测数据,采用Mann-Kendall法对径流量数据进行突变检验,并结合径流过程线共同判断突变年份,最终确定2008年为径流量变化的突变年份。以径流突变年份分割时间序列为1960~2008年和2009~2012年,得到累积径流量、累积降水量与年份线性关系式。沱沱河以上降水和非降水因素对径流量增大的贡献率分别为22.89%和77.11%;直门达以上分别为67.85%和32.15%。研究结果显示长江源区近年来径流量呈增加趋势。     

黑河出山径流的非线性特征分析

应用非线性动力学的理论和方法,对黑河出山径流的非线性特征进行了分析.结果表明,黑河月出山径流的年内分布、年平均流量的一次峰、谷变化符合单重或双重威布尔分布,并具有自相似性质.黑河出山径流多年变化在相空间中的运动轨迹收缩到一个约为4.32维的吸引子上,而描述流量的动力方程需要8个独立变量.黑河出山径流的非线性特征还表现在对内部结构为非线性函数的输入输出模型的良好应用上,如GRNN神经网络模型、非线性回归模型等.