Multiple time scale analysis of river runoff using wavelet transform for Dagujia River Basin, Yantai, China

Based on monOdy river runoff and meteorological data, a method of Morlet wavelet transform was used to analyze the multiple time scale characteristics of river runoffin the Dagnjia River Basin, Yantai City, Shandong Province. The results showed that the total annual river runoff in the Dagujia River Basin decreased significantly from 1966 to 2004, and the rate of decrease was 48×106m3/10yr, which was higher than the mean value of most rivers in China. Multiple time scale characteristics existed, which accounted for different aspects of the changes in annual river runoff, and the major periods of the runoff time series were identified as about 28 years, 14 years and 4 years with decreasing levels of fluctuation. The river runoff evolution process was controlled by changes in precipitation to a certain extent, but it was also greatly influenced by human activities. Also, for different time periods and scales, the impacts of climate changes and human activities on annual river runoff evolution occurred at the same time. Changes in the annual river runoffwere mainly associated with climate change before the 1980s and with human activities after 1981.     

近55年来澜沧江流域降水时空变化特征分析

本文利用澜沧江流域及周边共30个气象站点1960-2014年的逐月降水数据,采用气候倾向率、Mann-Kendall趋势检验、Morlet小波分析、Co-Kriging插值以及重心模型等方法,分析了澜沧江流域降水的时空变化特征。结果表明：① 分析时段内全区、北部和中部年降水量呈现增加趋势,南部年降水量出现减少趋势。春季全区、北部、中部和南部降水均呈增加趋势;夏季均呈减少趋势;秋季全区和南部降水呈现减少趋势,北部和中部呈增加趋势;冬季全区、中部和南部呈下降趋势,只有北部呈增加趋势。② 近55年来,全区包括北部、中部和南部年降水都存在近29年、近22年和5-10年左右的周期,这3个周期在分析时段内表现很稳定,具有全域性。全区、北部和南部还存在明显的13年左右的周期,中部1975年前和1995年后也存在13年左右的周期,北部1975年前存在明显的7-10年的周期,1995年后,7-10年的周期表现也比较稳定。降水量变化的第一主周期是近29年,第二主周期是近22年。③ 澜沧江流域多年平均降水量由南部向北部减少,流域南部降水最多,多年平均降水量在1200 mm以上,中部多年平均降水量处于800~1100 mm,北部多年平均降水量多小于800 mm,大部分在400~800 mm;澜沧江流域年降水重心和月降水重心都集中在中部,其中11月的降水重心迁移距离最大,向东南方向迁移了131.82 km。从季节来看,春季、夏季和秋季降水重心向东南迁移,冬季的向西北方向迁移,雨季降水重心相对比较集中,旱季降水重心相对 比较分散。     

Multi-Time Scale Analysis of Runoff at the Yangtze Estuary Based on the Morlet Wavelet Transform Method

Runoff series of the Yangtze River presents an intricate variation tendency under the reinforced influence of human activities.The Morlet Wavelet Transform method has been applied to analyze the annual runoff data from 1950 to 2011 at the Yangtze River Estuary.It can clearly reveal the multi-time scales structure,break point,change and distribution of periodic variation in the different time scales of the runoff series.The main conclusions are that：1） Repeated periodic oscillations accompanied by an extremely large fluctuation are presented in the runoff series with an obvious difference between wet and dry years,and the major periods of the time series are about 3,8,16 and 23 years respectively.Among them,the presented maximum periodic oscillation is 23 years scale.2） In the 23-year time scale,the wet periods are 1950-1958,1969-1980 and 1992-2003,and the dry periods are 1959-1968,1981-1991 and 2004-2011.3） It can be predicted from the view of long time scales that the low annual runoff will likely occur in the near future.     

Multiple Time-scale Characteristics of Runoff Variations in Middle Reaches of Huolin River and Their Effects

The Huolin River is one of the most important water sources for Xianghai wetland, Horqin wetland, and Chaganhu wetland in the western Songnen Plain of Northeast China. The annual runoff series of 46 years at Baiyun- hushuo Hydrologic Station, which is located in the middle reaches of the Huolin River, were analyzed by using wavelet analysis. Main objective was to discuss the periodic characteristics of the runoff, and examine the temporal patterns of the Huolin River recharging to the floodplain wetlands in the lower reaches of the river, and the corresponding effects of recharging variation on the environmental evolution of the wetlands. The results show that the annual runoff varied mainly at three time scales. The intensities of periodical signals at different time scales were strongly characterized by local distribution in its time frequency domain. The interdecadal variation at a scale of more than 30yr played a leading role in the temporal pattern of runoff variation, and at this scale, the runoff at Baiyunhushuo Hydrologic Station varied in turn of flood, draught and flood. Accordingly, the landscape of the floodplain wetlands presented periodic features, es- pecially prominent before the 1990s. Compared with intense human activities, the runoff periodic pattern at middle (10-20yr) and small (1-10yr) scales, which has relatively low energy, exerted unobvious effects on the environmental evolution of the floodplain wetlands, especially after the 1990s.     

Runoff change of Naoli River in Northeast China in 1955–2009 and its influencing factors

Runoff change and trend of the Naoli River Basin were studied through the time series analysis using the data from the hydrological and meteorological stations. Time series of hydrological data were from 1957 to 2009 for Bao′an station, from 1955 to 2009 for Baoqing station, from 1956 to 2009 for Caizuizi station and from 1978 to 2009 for Hongqiling station. The influences of climate change and human activities on runoff change were investigated, and the causes of hydrological regime change were revealed. The seasonal runoff distribution of the Naoli River was extremely uneven, and the annual change was great. Overall, the annual runoff showed a significant decreasing trend. The annual runoff of Bao′an, Baoqing, and Caizuizi stations in 2009 decreased by 64.1%, 76.3%, and 84.3%, respectively, compared with their beginning data recorded. The wet and dry years of the Naoli River have changed in the study period. The frequency of wet year occurrence decreased and lasted longer, whereas that of dry year occurrence increased. The frequency of dry year occurrence increased from 25.0%-27.8% to 83.9%-87.5%. The years before the 1970s were mostly wet, whereas those after the 1970s were mostly dry. Precipitation reduction and land use changes contributed to the decrease in annual runoff. Rising temperature and water project construction have also contributed important effects on the runoff change of the Naoli River.     

Long-term trend and fractal of annual runoff process in mainstream of Tarim River

Based on the time series data from the Aral hydrological station for the period of 1958-2005, the paper reveals the long-term trend and fractal of the annual runoff process in the mainstream of the Tarim River by using the wavelet analysis method and the fractal theory. The main conclusions are as follows： 1） From a large time scale point of view, i.e. the time scale of 16 （24） years, the annual runoff basically shows a slightly decreasing trend as a whole from 1958 to 2005. If the time scale is reduced to 8 （23） or 4 （22） years, the annual runoff still displays the basic trend as the large time scale, but it has fluctuated more obviously during the period. 2） The correlation dimension for the annual runoff process is 3.4307, non-integral, which indicates that the process has both fractal and chaotic characteristics. The correlation dimension is above 3, which means that at least four independent variables are needed to describe the dynamics of the annual runoff process. 3） The Hurst exponent for the first period （1958-1973） is 0.5036, which equals 0.5 approximately and indicates that the annual runoff process is in chaos. The Hurst exponents for the second （1974-1989） and third （1990-2005） periods are both greater than 0.50, which indicate that the annual runoff process showed a long-enduring characteristic in the two periods. The Hurst exponent for the period from 1990 to 2005 indicates that the annual runoff will show a slightly increasing trend in the 16 years after 2005.     

龙泉驿地区降水的多尺度特征及集中性研究

针对强降水是龙泉驿地区滑坡泥石流等地质灾害产生的重要诱因的问题,通过趋势分析法、Morlet小波分析方法、统计分析等分析了龙泉驿地区降水整体趋势,年、季降水量及降水日数的多尺度变化特征,及月、旬、日降水的集中性特征。结果表明,龙泉驿地区年季降水量总体呈下降趋势,但2006年后降水量开始显示出增加趋势。年降水量显示出3年、9年左右的准周期震荡,降水13数周期震荡则比较复杂。2008年以后龙泉驿地区年、季降水处于丰水期,降水集中性显著,降水强度有增大趋势,夏秋季有发生地质灾害的可能性。可诱发龙泉驿地区地质灾害的主要降水时段和降水比重极值时段为7、8月,1980年代初中期降水集中性主要出现在7月份,1980年代中后期至2000年代主要出现在8月份。19--25旬是降水的集中性时段,而日降水高峰时段出现在0：00～7：00时段尤其是2：00～5：00时段。     

Climate change and its effects on runoff of Kaidu River,Xinjiang, China: A multiple time-scale analysis

This paper applied an integrated method combining grey relation analysis, wavelet analysis and statistical analysis to study climate change and its effects on runoff of the Kaidu River at multi-time scales. Maj or findings are as follows： 1） Climatic factors were ranked in the order of importance to annual runoff as average annual temperature, average temperature in autumn, average temperature in winter, annual precipitation, precipitation in flood season, av- erage temperature in summer, and average temperature in spring. The average annual temperature and annual precipitation were selected as the two representative factors that impact the annual runoff. 2） From the 32-year time scale, the annual runoff and the average annual temperature presented a significantly rising trend, whereas the annual precipitation showed little increase over the period of 1957-2002. By changing the time scale from 32-year to 4-year, we observed nonlinear trends with increasingly obvious oscillations for annual runoff, average annual temperature, and annual precipitation. 3） The changes of the runoff and the regional climate are closely related, indicating that the runoff change is the result of the regional climate changes. With time scales ranging from 32-year, 16-year, 8-year and to 4-year, there are highly significant linear correlations between the annual runoff and the average annual temperature and the annual precipitation.     

STUDY ON EVAPORATION OF BIELAHONG RIVER BASIN

Asatypicalmarshriver,theBielahongRiverliesinthehinterlandofthehoiangPlain.ItrisesinandgoeSthroughl~areasofplainma-rsh.Themarshrateinthebasinis45Percent.ThehydrologicalcharacteristicsoftheBielahongRiverbasincanreflectthehydrologicalcharacteristicsofthewholernaxshplain.Thereare1.119x106hamarshintheSanjiangPlain.AlterlOng-timedevelopment,marshisstillthemainnaturallandscapeandsoiltypeintheplain.Waterisoneofthemostactiveelementsinmarshecosystem.Itaffectsplantsgrowth,speciesdistribution,soilfo…     

AN ANALYSIS OF THREE ELEMENTS OF WATER BALANCE IN THE CHANGJIANG RIVER BASIN

The general trend of three elements (precipitation, runoff and evaporation) of the water balance of the Changjiang River Basin is discussed from the regional distribution of the mean annual values of view, i.e. isogram. The distribution of precipitation is non-uniform. The distribution of runoff mainly supplied from precipitation is more uniform than that of precipitation. The distribution of the evaporation from land is much more uniform than that of precipitation and runoff. Time distribution of these three elements shows the characteristics of comparatively distinct yearly variation and few variation between years. The relationship between precipitation and runoff, and between precipitation and evaporation in the humid region in the Changjiang River is analyzed. The slopes of their straight line correlation are nearly equal. The internal relationship between variables should be paid attention to, otherwise, a pseudo correlation may be resulted in. The paper provides the method of quantitative computa     

Spatio-temporal trends and causes of variations in runoff and sediment load of the Jinsha River in China

The Jinsha River Basin is an important basin for hydropower in China and it is also the main runoff and sediment source area for the Yangtze River,which greatly influence the runoff and sediment in the Three Gorges Reservoir.This study aims to characterize the spatial distribution,inter-annual variation of runoff and sediment load in the Jinsha River Basin,and to analyze the contribution of rainfall and human activities to the runoff and sediment load changes.The monitoring data on runoff,sediment load and precipitation were collected from 11hydrological stations in the Jinsha River Basin from1966 to 2016.The data observed at the outlet of the basin showed that 71.4%of the runoff is from the upper reaches of the Jinsha River Basin and the Yalong River,while 63.3%of the sediment is from the lower reaches(excluding the Yalong River).There is no significant increase in runoff on temporal scale in the Jinsha River Basin,while it has an abrupt change in runoff in both upstream and midstream in 1985,and an abrupt change in downstream in 1980 and2013.The sediment load demonstrated a significantincreasing trend in the upstream,no significant reducing trend in the midstream,but significant reducing trend in the downstream.The sediment load in upstream showed abrupt change in 1987,in midstream in 1978 and 2014,in downstream in 2012.Rainfall dominated runoff variation,contributing more than 59.0%of the total variation,while human activity,including reservoirs construction,the implementation of soil and water conservation projects,is the major factor to sediment load variation,contributing more than 87.0%of the total variation.     

Influence of vegetation on runoff and sediment in wind-water erosion crisscross region in the upper Yellow River of China

All characteristics of vegetation,runoff and sediment from 1960 to 2010 in the Xiliu Gully Watershed,which is a representative watershed in wind-water erosion crisscross region in the upper reaches of the Yellow River of China,have been analyzed in this study.Based on the remote sensing image data,and used multi-spectral interpretation method,the characteristics of vegetation variation in the Xiliu Gully Watershed have been analyzed.And the rules of precipitation,runoff and sediment's changes have been illuminated by using mathematical statistics method.What′s more,the influence mechanism of vegetation on runoff and sediment has been discussed by using the data obtained from artificial rainfall simulation test.The results showed that the main vegetation type was given priority to low coverage,and the area of the low vegetation coverage type was reducing year by year.On the country,the area of the high vegetation coverage type was gradually increasing.In a word,vegetation conditions had got better improved since 2000 when the watershed management project started.The average annual precipitation of the river basin also got slightly increase in 2000–2010.The average annual runoff reduced by 37.5%,and the average annual sediment reduced by 73.9% in the same period.The results of artificial rainfall simulation tests showed that the improvement of vegetation coverage could increase not only soil infiltration but also vegetation evapotranspiration,and then made the rainfall-induced runoff production decrease.Vegetation root system could increases the resistance ability of soil to erosion,and vegetation aboveground part could reduce raindrop kinetic energy and splash soil erosion.Therefore,with the increase of vegetation coverage,the rainfall-induced sediment could decrease.     

Variations and trends of trans-boundary runoff in the longitudinal range-gorge region

The mountainous hydrological process usually shows high variation to climate change and human action. In the Longitudinal Range-Gorge Region (LRGR), Southwestern China and Southeast Asian, the transboundary runoff variations are much more sensitive and complex under the interaction of climate change, “corridor-barrier” functions in LRGR, and dams building. In this paper, based on the long hydrological records (1956-2013) from three mainstream hydrological stations in Nu River, Lancang River, and Red River, the region runoff variations were analyzed. The results show out: i) the regional runoff changes were strongly influenced by the “Corridor-Barrier” functions in LRGR from west to east, the variability extent of annual runoff increased, but tended to decrease after 2009 and the reduced extents also increased; ii) the annual runoff change in the three rivers had high concentration degrees; iii) there were periodicities of 33 years of runoff change in Nu River and Lancang River, and 30 years in Red River, and the lower flow period would continue for 8-9 years in Nu River and Lancang River but only for 4 years in Red River; iv) since 2010, as the two mega dams of Xiaowan and Nuozhadu built in Lancang River mainstream, their variations of annual runoff were quite different. The research results could offer a scientific base for sustainable utilization, conservation, and management of the regional water resources     

金沙江流域年与季气候特征统计分析

利用金沙江流域30个气象站46年的气温与降水资料,运用线性相关分析法和小波分析法对金沙江流域的气温和降水在年与四季中的变化及空间分布特征进行分析。结果表明:流域的年均气温在20世纪90年代后呈明显上升趋势,冬季增温效应最明显;流域的降水量总体呈不明显的增加趋势,春冬两季的降水量变化较明显。至2006年后,除时间尺度6a以下,流域的气温在其他时间尺度上将处于偏高期。夏秋两季降水量在2006年后将处于偏低期,年、春冬两季降水量则将处于偏高期。流域的气温变化具有区域性差别,高值区与低值区分别位于流域的下游和上游地区;而降水的发生主要在流域的东北部。     

Runoff responses to climate change in arid region of northwestern China during 1960–2010

Based on runoff, air temperature, and precipitation data from 1960 to 2010, the effects of climate change on water resources in the arid region of the northwestern China were investigated. The long-term trends of hydroclimatic variables were studied by using both Mann-Kendall test and distributed-free cumulative sum (CUSUM) chart test. Results indicate that the mean annual air temperature increases significantly from 1960 to 2010. The annual precipitation exhibits an increasing trend, especially in the south slope of the Tianshan Mountains and the North Uygur Autonomous Region of Xinjiang in the study period. Step changes occur in 1988 in the mean annual air temperature time series and in 1991 in the precipitation time series. The runoff in different basins shows different trends, i.e., significantly increasing in the Kaidu River, the Aksu River and the Shule River, and decreasing in the Shiyang River. Correlation analysis reveals that the runoff in the North Xinjiang (i.e., the Weigan River, the Heihe River, and the Shiyang River) has a strong positive relationship with rainfall, while that in the south slope of the Tianshan Mountains, the middle section of the north slope of the Tianshan Mountains and the Shule River has a strong positive relationship with air temperature. The trends of runoff have strong negative correlations with glacier coverage and the proportion of glacier water in runoff. From the late 1980s, the climate has become warm and wet in the arid region of the northwestern China. The change in runoff is interacted with air temperature, precipitation and glacier coverage. The results show that streamflow in the arid region of the northwestern China is sensitive to climate change, which can be used as a reference for regional water resource assessment and management.     

近60年“雅安天漏”变化特征分析

针对雅安地区特殊的"天漏"气候特征及以往对其变化特征研究较少问题,利用雅安市1951~2010年降水资料,从降水量和雨日数出发,通过回归分析、小波分析等现代气候统计诊断方法,综合分析"雅安天漏"的变化特征。结果表明:在降水量上,雅安市年降水量总体呈显著减小趋势,20世纪90年代中期以后尤为明显;从季节尺度上来看,春、夏、秋三季降水量呈现明显减少趋势,但冬季与之相反;从逐月降水比重可以看出,极大值主要出现在7、8、9月;从量级上看,小雨、中雨、大雨的降水量均在减小,暴雨却在增加,但各量级降水所产生的降水量与全年总降水量的比值相对比较稳定。从雨日数上看,雅安市四季的雨日数均表现出减少趋势,各个强度量级的雨日数也均在波动减小。小波分析结果显示:年降水量和雨日数在年代际时间尺度均存在准周期振荡。     

Impacts of Climatic Factors on Runoff Coefficients in Source Regions of the Huanghe River

Runoff coefficients of the source regions of the Huanghe River in 1956–2000 were analyzed in this paper. In the 1990s runoff of Tangnaihai Hydrologic Station of the Huanghe River experienced a serious decrease, which had at- tracted considerable attention. Climate changes have important impact on the water resources availability. From the view of water cycling, runoff coefficients are important indexes of water resources in a particular catchment. Kalinin baseflow separation technique was improved based on the characteristics of precipitation and streamflow. After the separation of runoff coefficient (R/P), baseflow coefficient (Br/P) and direct runoff coefficient (Dr/P) were estimated. Statistic analyses were applied to assessing the impact of precipitation and temperature on runoff coefficients (including Dr/P, Br/P and R/P). The results show that in the source regions of the Huanghe River, mean annual baseflow coefficient was higher than mean annual direct runoff coefficient. Annual runoff coefficients were in direct proportion to annual pre- cipitation and in inverse proportion to annual mean temperature. The decrease of runoff coefficients in the 1990s was closely related to the decrease in precipitation and increase in temperature in the same period. Over different sub-basins of the source regions of the Huanghe River, runoff coefficients responded differently to precipitation and temperature. In the area above Jimai Hydrologic Station where annual mean temperature is –3.9oC, temperature is the main factor in- fluencing the runoff coefficients. Runoff coefficients were in inverse relation to temperature, and precipitation had nearly no impact on runoff coefficients. In subbasin between Jimai and Maqu Hydrologic Station Dr/P was mainly affected by precipitation while R/P and Br/P were both significantly influenced by precipitation and temperature. In the area be-tween Maqu and Tangnaihai hydrologic stations all the three runoff coefficients increased with the rising of annual precipitation, while direct runoff coefficient was inversely proportional to temperature. In the source regions of the Huanghe River with the increase of average annual temperature, the impacts of temperature on runoff coefficients be-come insignificant.     

Wavelet analysis and nonparametric test for climate change in Tarim River Basin of Xinjiang during 1959–2006

Using wavelet analysis, regression analysis and the Mann-Kendall test, this paper analyzed time-series (1959–2006) weather data from 23 meteorological stations in an attempt to characterize the climate change in the Tarim River Basin of Xinjiang Uygur Autonomous Region, China. Major findings are as follows: 1) In the 48-year study period, average annual temperature, annual precipitation and average annual relative humidity all presented nonlinear trends. 2) At the 16-year time scale, all three climate indices unanimously showed a rather flat before 1964 and a detectable pickup thereafter. At the 8-year time scale, an S-shaped nonlinear and uprising trend was revealed with slight fluctuations in the entire process for all three indices. Incidentally, they all showed similar pattern of a slight increase before 1980 and a noticeable up-swing afterwards. The 4-year time scale provided a highly fluctuating pattern of periodical oscillations and spiral increases. 3) Average annual relative humidity presented a negative correlation with average annual temperature and a positive correlation with annual precipitation at each time scale, which revealed a close dynamic relationship among them at the confidence level of 0.001. 4) The Mann-Kendall test at the 0.05 confidence level demonstrated that the climate warming trend, as represented by the rising average annual temperature, was remarkable, but the climate wetting trend, as indicated by the rising annual precipitation and average annual relative humidity, was not obvious.     

Morlet变换在超宽频带地震仪记录的汶川震前数据处理中的应用

介绍了Morlet小波变换的基本原理和特点。以汶川地震为例,选取2008-05-01~05-12的地震计垂直向连续波形数据,使用Morlet小波变换得到时频谱。分析时频图发现,在汶川地震发生前的数十h中,0.1~0.2 Hz频段的能量幅值出现明显的递增趋势,是非台风扰动引起的频率异常,与已有论文结论符合良好,证明Morlet小波变换是分析震前频率特征的有效方法。     

Regimes of Runoff Components on the Debris-covered Koxkar Glacier in Western China

By using a degree-day based distributed hydrological model, regimes of glacial runoff from the Koxkar glacier during 2007-2011 are simulated, and variations and characteristics of major hydrological components are discussed. The results show that the meltwater runoff contributes 67.4%, of the proglacial discharge, out of which snowmelt, clean ice melting, buried-ice ablation and ice-cliff backwasting account for 22.4%, 21.9%, 17.9% and 5.3% of the total melt runoff, respectively. Rainfall runoff is significant in mid-latitude glacierized mountain areas like Tianshan and Karakorum. In the Koxkar glacier catchment, about 11.5% of stream water is initiated from liquid precipitation. Spatial distributions for each glacial runoff component reveal the importance of climatic gradients, local topography and morphology on glacial runoff generation, and temporal variations of these components is closely related to the annual cycle of catchment meteorology and glacier storage. Four stages are recognized in the seasonal variations of glacier storage, reflecting changes in meltwater yields, meteorological conditions and drainage systems in the annual hydrological cycle.