Climate changes and their impacts on water resources in the arid regions: a case study of the Tarim River basin, China

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1 Stoch Environ Res Risk Assess (2010) 24: DOI /s ORIGINAL PAPER Climate changes and their impacts on water resources in the arid regions: a case study of the Tarim River basin, China Qiang Zhang Æ Chong-Yu Xu Æ Hui Tao Æ Tao Jiang Æ Yongqin David Chen Published online: 25 June 2009 Ó Springer-Verlag 2009 Abstract Streamflow series of five hydrological stations were analyzed with aim to indicate variability of water resources in the Tarim River basin. Besides, impacts of climate changes on water resources were investigated by analyzing daily precipitation and temperature data of 23 meteorological stations covering Some interesting and important results were obtained: (1) the study region is characterized by increasing temperature, however, only temperature in autumn is in significant increasing trend; (2) precipitation changes present different properties. Generally, increasing precipitation can be detected. However, only the precipitation in the Tienshan mountain area is in significant increasing trend. Annual streamflow of major rivers of the Tarim River basin are not in significant trends, except that of the Akesu River which is in significantly increasing trend. Due to the geomorphologic properties of the Tienshan mountain area, precipitation in this area demonstrates significant increasing Q. Zhang (&) T. Jiang Department of Water Resources and Environment, Sun Yat-sen University, Guangzhou, China zhangqnj@gmail.com C.-Y. Xu Department of Geosciences, University of Oslo, PO Box 1047, Blindern, 0316 Oslo, Norway H. Tao Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing, China Y. D. Chen Department of Geography and Resource Management, The Chinese University of Hong Kong, Hong Kong, China trend and which in turn leads to increasing streamflow of the Akesu River. Due to the fact that the sources of streamflow of the rivers in the Tarim River basin are precipitation and melting glacial, both increasing precipitation and accelerating melting ice has the potential to cause increasing streamflow. These results are of practical and scientific merits in basin-scale water resource management in the arid regions in China under the changing environment. Keywords Climate change Mann Kendall trend test Water resources The arid regions Tarim River basin 1 Introduction Water plays the key role in human society and nature which greatly underscores the better understanding of how changes in climate could affect regional water supplies, particularly in the arid regions (Houghton et al. 2001; Xu and Singh 2004; Hagg et al. 2007). The well-evidenced global warming and associated impacts on human society have drawn considerable concerns from academic circles, public and governments. Labat et al. (2004) indicated that the global warming led to alterations of the global hydrological cycle and to the increase amplitude of the global and continental runoff. Higher air temperatures result in higher evaporation rates, higher atmospheric water vapor content, and consequently, an accelerated hydrological cycle (Menzel and Bürger 2002; Xu et al. 2006; Zhang et al. 2008a, b). Among the most significant potential consequences of regional climate change are alterations in regional hydrological cycles and subsequent changes in river regimes. However, the model intercomparison revealed that the relationship between the intensity of the

2 350 Stoch Environ Res Risk Assess (2010) 24: global hydrological cycle and global warming is not very robust (Douville et al. 2006). In terms of a specific regional scale, many studies reported large uncertainties in response of precipitation changes to global warming (e.g. Douville 2006). Even though several studies indicated that the anticipated global increase in precipitation may not be in association with accelerated or accelerating water cycle as a result of global warming (Bosilovich et al. 2005), many studies have shown that the impacts of climatic changes on global/regional water resources hinge on the influences of climatic changes on the spatial and temporal distribution of precipitation (e.g. Gao et al. 2007). Booij (2005) studied the impact of climate change on floods in the river Meuse (in western Europe), investigating variability and uncertainty of impacts of climate changes on river floods. Thus, it is necessary to better understand climate changes and possible impacts on water resource from the viewpoint of regional scale. Global warming has the potential to alter the spatial and temporal distribution of water resource, which exerts tremendous influences on the ecological environment and the agriculture development. Furthermore, the arid regions are more sensitive to variability and availability of water resource (in this study we only focus on ground-surface water) when compared to the humid regions. Therefore, good knowledge of variations of the water resource under the changing climate by taking a typical arid region as a case study is of great scientific and practical merits in sound understanding of the hydrological response to the climate changes and also in the water resource management in the arid regions of the world. This is the major motivation of this study. The north-west China is characterized by arid and semi-arid climate. Variability and availability of water resources have direct influences on local eco-environmental conservation and sustainable socio-economic development. The Tarim River is the longest inland river in China with an annual flow of 4 6 billion cubic meters. About 10 million population including ethnic minorities of Uyghurs and Mongolians live in this valley. The climate of this river basin is characterized by precipitation deficit and strong evaporation. Scientific problems of climate changes and water resources have drawn considerable concerns from academic circle (Feng et al. 2001; Song et al. 2002; Ye et al. 2006). Shi et al. (2003) indicated a transition from dry and warm climate to wet and warm climate in the north-west China. Due to paramount role of water resource in the sustainable development of socio-economy in the northwest China and distinct influences of climate changes on variability of water resource, it is desirable to analyze climate changes of the past decades, focusing on changes of precipitation and temperature, and the possible influences on streamflow variations, which forms the objective of the present study. 2 Study region: the Tarim River basin The Tarim River is 1,321 km in length, running west to east along the northern edge of the Taklimakan Desert. The drainage area of the Tarim River Basin is km 2, it is the largest inland river in China and is highly dependent on the water supply by the TienShan, Kunlun, Eastern Pamir and Karakorum high mountains that surround the basin. There are 114 rivers in the Tarim River Basin, forming 9 drainage systems: Aksu, Hotan, Yarkant, Qarqan, Keriya, Dina, Kaxgar, Kaidu Konqi Rivers. There are only four headstreams (Hotan, Yarkand, Akesu and Kaidu Rivers) feeding the mainstream of the Tarim River. The annual mean air temperature is C. Monthly mean temperature is between 20 to 30 C in July and -10 to -20 C in January. The extreme maximum and minimum temperature of the Tarim River basin are 43.6 and C, respectively. The multi-annual mean precipitation is mm, wherein more than 80% of total precipitation falls during May September. The river is the most important source of water in the arid lowlands of Tarim Basin, with more than 8 million people living in oases clustered along its banks and in an alluvial plain downstream. Due to its exceptional role in sustainable development of local socio-economy, the central government of China launched a five- year emergency water diversion program in 2000 with 10.7 billion yuan (US$1.3 billion) earmarked for the reclamation of the river and Taitema Lake (Tao et al. 2008). There are some studies focusing on the impacts of climate changes on water resource in the Tarim River basin (e.g. Chen et al. 2006). However, the previous studies focused on site-specific station, but not comprehensive study in space and time, which tends to limit our understanding of influences of climate changes on water resources from the viewpoint of time and space. Actually, climate changes do impact water resource variability in space and time. Therefore, it is necessary to comprehensively analyze the climate changes and associated influences on water resource changes in time and space. However, no such reports are available from viewpoint of both space and time. 3 Data and methods 3.1 Data Daily precipitation and temperature data for were collected from 24 national standard rain stations in the Tarim River basin (Fig. 1). There are a few missing data in the daily precipitation and temperature dataset (less than 0.01% of the total observations). The missing precipitation and temperature data are filled by the mean

3 Stoch Environ Res Risk Assess (2010) 24: Fig. 1 Location of the Tarim River basin, rain gauging stations and hydrological stations values of the neighboring days. If more than two days have missing data, we filled them with values of its neighboring stations by building regressive relations between stations. The results show the R 2 value as high as [0.85. We consider the gap filling method will have no influence on the long-term temporal trend. Furthermore, the data consistency was checked by the double-mass method and the result revealed that all the data series used in the study are consistent. Moreover, annual total streamflow dataset for from six hydrological stations are collected and analyzed to demonstrate long-term trend of streamflow variations. Locations of these six hydrological stations can be referred to Fig. 1 and more detailed information can be referred to Table 1. The trends in this study only represent the time interval considered in this study. 3.2 Methodology There are many statistical techniques available to detect trends within the time series such as moving average, linear regression, Mann Kendall trend test, filtering technology, etc. Each method has its own strength and weakness in trend detection. However, non-parametric trend detection methods are less sensitive to outliers than are parametric statistics such as Pearson s correlation coefficient. Moreover, the rank-based nonparametric Mann Kendall test (Kendall 1975; Mann 1945) can test trends in a time series without requiring normality or linearity, and is therefore highly recommended for general use by the World Meteorological Organization (Mitchell et al. 1966). The Mann Kendall trend test has been widely used in detection of trends in meteorological and hydrological series (Chen et al. 2007; Burn 2008). This paper also uses the Mann Kendall (MK) test method to analyze trends within the precipitation, temperature and annual streamflow series across the Tarim River basin. The procedure of MK trend test adopted in this study is as follows: First the MK test statistic is calculated as X n S ¼ Xn 1 sgnðx j x i Þ i¼1 j¼iþ1 8 < þ1; x j [ x i where sgnðx j x i Þ¼ 0; x j ¼ x i : 1; x j \x i ð1þ Table 1 Annual streamflow changes in the headstreams of Tarim River basin ( ) Water system Hydrological stations Drainage area (km 2 ) Multi-annual average streamflow (10 8 m 3 ) Percentage of melting ice (%) Significance (0.05) M K trend Hotan River Tommguziluoke 14, No Wuluwati 19, No Aksu River Xiehela 12, Yes 4.41 Shaliguilanke 19, Yes 3.88 Yarkant River Kaqun 50, No 1.11 Kaidu River Dashankou 19, No 1.79

4 352 Stoch Environ Res Risk Assess (2010) 24: and n is the sample size. The statistics S is approximately normally distributed when n C 8, with the mean and the variance as follows: ES ð Þ ¼ 0 ð2þ VðSÞ ¼ nðn 1Þð2n þ 5Þ P n i¼1 t iiði 1Þð2i þ 5Þ ð3þ 18 where t i is the number of ties of extent i. The standardized statistics (Z) for one-tailed test is formulated as: 8 pffiffiffiffiffiffiffiffiffiffiffiffi S 1 S [ 0 >< VarðSÞ Z ¼ 0 S ¼ 0 >: pffiffiffiffiffiffiffiffiffiffiffiffi Sþ1 S\0 VarðSÞ ð4þ Temperature ( o C) Precipitation (mm) A B At the 5% significance level, the null hypothesis of no trend is rejected if Z [ Influence elimination of serial correlation (if it is significant at [95% confidence level) on the Mann Kendall (MK) test has been discussed (Khaled and Rao 1998; Yue and Wang 2002). In this paper, effective sample size (ESS) proposed by Yue and Wang (2004) is used to modify the variance of the MK statistic to reduce the influence of the presence of serial correlation on the MK test. The procedure is as follows (Yue and Wang 2004): (1) remove the existing trend from the series if it exists; (2) the sample serial correlation is estimated using the detrended series; and (3) the MK test modified by ESS is applied to assess the significance of trend in the original time series. The significance of the trend was tested at [95% confidence level. Moreover, the simple linear regression method, a parametric T test method, is also used in this paper to detect long-term trends within the hydro-meteorological series. The computation procedure consists of two steps, fitting a linear simple regression equation with the time t as independent variable and the hydrological variable (in this case areal average temperature, precipitation and annual streamflow series), Y as dependent variable, and testing the statistical significance of the slope of the regression equation. The parametric T test requires the data to be tested is normally distributed. The normality of the data series is first tested in the study by applying the Kolmogorov Smirnov test. The method first compares the specified theoretical cumulative distribution function (in our case normal distribution) with the sample cumulative density function based on observations, then calculates the maximum deviation, D, of the two. If, for the chosen significance level, the observed value of D is greater than or equal to the critical tabulated value of the Kolmogorov Smirnov statistic, the hypothesis of normal distribution is rejected. Fig. 2 Long term areal monthly average precipitation (a) and temperature (b) of the Tarim River basin ( ) 4 Results and discussion 4.1 Precipitation and temperature changes In the Tarim River basin, precipitation mainly occurs during May August. November, December, January and February are the dry months (Fig. 2). High monthly mean temperature is observed mainly during June-August and low monthly mean temperature in December, January and February (Fig. 2). Before further trend detection analysis, we performed thorough analysis on the serial persistence within the meteor-hydrological series station by station in the Tarim River basin. For the size of this paper, we can not demonstrate all the results here. Thus, we just show autocorrelation analysis results of three series randomly selected from the dataset. Figure 3 illustrates parts of the results for case studies. It can be seen from Fig. 3 that the series include independent observations both for annual streamflow series and for annual mean temperature and annual precipitation series at 95% confidence level. This result justifies the application of MK trend detection technique in this study. Even so, we still considered possible influences of serial persistence within the series on the MK trend detection based on the method mentioned in the Methodology section. 4.2 Spatial distribution of trends of precipitation and temperature changes Precipitation and temperature changes exert considerable influence on availability of water resources from the viewpoint of space and time. Figures 4 and 5 demonstrate spatial patterns of seasonal precipitation and temperature changes in the Tarim River basin. It can be seen from

5 Stoch Environ Res Risk Assess (2010) 24: ACF ACF ACF Autocorrelation analysis for annual streamflow series Autocorrelation analysis for annual precipitation series Autocorrelation analysis for annual temperature series Lag time Fig. 3 Autocorrelation analysis of meteor-hydrological series of the Tarim River basin. All the meteor-hydrological series of the Tarim River basin were analyzed station by station for serial persistence detection. The series in this figure are shown as a case study. The dashed lines denote 95% confidence level. ACF means autocorrelation functions Fig. 4a that stations characterized by significant increasing annual precipitation changes mainly concentrated in the regions north to the Taklimakan Desert. Specifically, significant increasing precipitation can be observed mainly in the Toxkan River, Kargar River, Weigan River and Kaidu River. No significant annual precipitation changes can be detected in west, south-west and south parts of the Tarim River basin. With respect to precipitation changes in spring (Fig. 4b), summer (Fig. 4c), autumn (Fig. 4d) and winter (Fig. 4e), more stations show significant increasing precipitation in summer when compared to other three seasons, i.e. spring, autumn and winter. In summer, 10 out of 24 stations exhibit significant increasing precipitation, accounting for 41.7% of total stations studied in this paper. Only 1 3 stations show significant increasing precipitation in other three seasons (Figs. 4b, d, e). Stations with significant increasing precipitation in summer distribute sporadically and widely across the whole Tarim River basin. However, comparatively, stations also seem to converge to the north parts of the Tarim River basin, Weigan and Dina rivers in particular. Stations with significant precipitation in winter also concentrate in this area (Fig. 4e). When compared to precipitation changes, more stations in the Tarim River basin show significant increasing temperature (Fig. 5). For annual temperature changes, only 3 out of 24 stations show no significant temperature trends. Comparatively, more stations show no significant temperature changes in spring than in summer, autumn and winter. This point is further corroborated by our previous study (Zhang et al. 2008c). In autumn, 22 out of 24 stations show significant increasing temperature trend, accounting for 91.7% of total stations studied in this paper. In general, more significant increasing temperature trends are identified in autumn and winter. In summer, 16 out of 24 stations exhibit significant increasing temperature trends, accounting for 66.7% of the total stations studied in the paper. Generally, stations characterized by no significant temperature trends are found mainly in the west part of the Tarim River basin. 4.3 Changes of streamflow and glacier in the main tributaries Generally speaking, streamflow changes are mainly the results of precipitation changes. Runoff in the June August flood season accounts for 60 80% of the annual total runoff (Chen et al. 2003). However, due to unique climatic properties and geographical location of the Tarim River basin, streamflow changes of the Tarim River basin are also partly influenced by temperature changes due to the fact that temperature can impact melting of glacier and evaporation variations. Glacier melt and snowmelt make up 48.2% of the total runoff of the river (Chen et al. 2006). Glaciers, snowmelt and precipitation in the surrounding mountains are the source of runoff for the Tarim River. Therefore, it is important to analyze the streamflow changes and possible impacts from temperature and melting ice, and to discuss possible contribution of snowmelt to the changes of streamflow variations of the Tarim River basin. It can be seen from Fig. 6 that different changing characteristics can be observed for streamflow changes of hydrological gauging stations in the main tributaries of the Tarim River basin. More detailed information of these hydrological stations and significance of trends can be referred to Table 1. Increasing streamflow trends can be detected in Xiehela station, Shaliguilanke station, Kaqun station and Dashankou station and it is particularly the case for the Xiehela, Shaliguilanke and Dashankou stations. Figure 1 shows that these three stations are located in the north Tarim River basin. Figure 6 also demonstrates larger increasing magnitude of streamflow of the Xiehela, Shaliguilanke and Dashankou stations can be found after about 1990s when precipitation and temperature are also characterized by abrupt increase (Xu et al. 2004). Decreasing trends of streamflow changes can be identified in Tommguziluoke station and Wuluwati station (Fig. 6). Table 1 indicates that significant trends can be detected only for Xiehela station and Shaliguilanke station of the Aksu River. The streamflow changes of other four stations are not significant at [95% confidence level. Figure 6 also indicates slight trough values of streamflow for the six

6 354 Stoch Environ Res Risk Assess (2010) 24: A B C Fig. 4 Spatial distribution of MK trends within precipitation changes in the Tarim basin, China. a Annual, b spring, c summer, d autumn, e winter. Filled triangle denotes significant increasing trend; filled D inverted triangle denotes significant decreasing trend; and open circle denotes no significant trend E hydrological stations during about Figures 1 and 4 indicate that hydrological stations with significant increasing streamflow changes are located in the regions where stations with significant increasing annual precipitation stand. Because most stations show significant increasing temperature trends and these stations distribute sporadically and widely across the Tarim River basin, no fixed and confirmed relations can be established between streamflow changes and temperature changes. Decreasing streamflow of Tommguziluoke station and Wuluwati station may be partly due to no significant precipitation trends in the west and southwest parts of the Tarim River basin. Furthermore, although the glacial meltwater account a large proportion of the streamflow of Hotan river (Table 1), most of the glaciers of this sub-basin mainly locate in the temperature dropping belt in the north of Tibetan Plateau (Shi et al. 2006). This result also further elucidated the possible causes behind the decreasing streamflow in Wuluwati and Tommguziluoke stations. Changes of glacier and number of advancing glaciers may well explain streamflow changes (Table 2; Liu et al. 2006). Table 2 lists glacier changes of four major tributaries: Aksu River, Kaidu River, Hotan River and Yarkant River. The least percentage of glacier area changes and large number of advancing of glaciers are observed in the Hotan River basin. Glaciers in the Kaidu River and Aksu River have the large percentage of changes and also large number of advancing glaciers. This may be due to significant increasing precipitation and no significant changes of temperature in this particular region. Streamflow of Dashankou, Xiehela and Shaliguilanke stations is in increasing trends and the increasing trends of streamflow series of Xiehela and Shaliguilanke stations are significant at 95% confidence level.

7 Stoch Environ Res Risk Assess (2010) 24: A B C Fig. 5 Spatial distribution of MK trends within temperature changes in the Tarim basin, China. a Annual, b spring, c summer, d autumn, e winter. Filled triangle denotes significant increasing trend; filled D inverted triangle denotes significant decreasing trend; and open circle denotes no significant trend E 5 Conclusions and discussions Based on daily temperature and precipitation dataset of 24 stations and annual streamflow series of 6 hydrological stations in the Tarim River basin, the typical arid region in China, we analyzed changing characteristics of seasonal precipitation and temperature changes from the standpoint of space and time. Possible impacts of snowmelt, precipitation and temperature on hydrological process of the Tarim River basin during past 40 years have also been discussed. Some interesting conclusions can be drawn in terms of climatic changes and associated impacts on availability and variability of water resource of the Tarim River basin. Climatic changes of the Tarim River basin are characterized by increasing precipitation and temperature. Increasing precipitation can be observed mainly in summer. Increasing temperature seems to occur mainly in winter when compared to other three seasons. Besides, increasing temperature changes seem to be more prevailing when compared to changes of precipitation. Significant increasing precipitation can be observed mainly in the regions north to the Taklimakan Desert. More stations show significant increasing precipitation in summer when compared to that in spring, autumn and winter. More stations show significant increasing temperature. Stations with no significant increasing temperature locate in the west and north parts of the Tarim River basin. Distribution of annual precipitation changes match well with distribution of stations with significant increasing streamflow, showing considerable impacts of annual precipitation changes on annual streamflow variations. Larger-magnitude of increase of annual streamflow can be detected at the Xiehela, Shaliguilanke and Dashankou

8 356 Stoch Environ Res Risk Assess (2010) 24: Fig. 6 Annual streamflow changes of major tributaries of the Tarim River basin. Annual streamflow changes of Xiehela and Shaliguilanke are significant at [95% confidence level Streamflow (10 8 m 3 ) 35 Tommguziluoke st Wuluwati st Streamflow (10 8 m 3 ) Xiehela st Shaliguilanke st Streamflow (10 8 m 3 ) 90 Kaqun st Dashankou st Table 2 Glacier changes in the main tributaries of the Tarim River in recent 40 years Rivers Time interval Number of glaciers Glacial area (km 2 ) Changes of area Percentage of changes (%) Number of advancing glaciers Aksu River Kaidu River Hotan River Yarkant River stations. Increasing precipitation and temperature are also found in these regions. Larger-magnitude of increase of annual streamflow in this region after 1990s corresponds well to the abrupt increase of precipitation and temperature. Southwest parts of the Tarim River basin where the Tongguziluoke, Wuluwati and Kaqun stations locate are dominated by not significant increasing precipitation and temperature changes. Besides, the least percentage of glacier area and large number of advancing of glaciers observed in the Hotan River basin can also explain not significant streamflow and even decreasing streamflow changes in the southwest parts of the Tarim River basin. What aforementioned further illustrates tremendous influences of climate changes on water resources within the Tarim River basin. Increasing snowmelt also contributes to the changes of streamflow. River basins with larger percentage of area changes of glacier are usually characterized by significant increasing streamflow. Hydrological stations in the Kaidu River, Aksu River and Yarkant River show increasing streamflow series. However, decreasing streamflow changes can be identified in the Hotan River which seem to correspond to smaller percentage of area changes of glacier. It should be noted here that impacts of climatic changes on water resources are complicated. Far more driving factors than precipitation, temperature and snowmelt can influence spatial and temporal changes of water resource of the Tarim River basin. Furthermore, complicated interplay can be expected between driving factors. Increasing temperature may cause increasing snowmelt and increasing precipitation may also give rise to increasing area of glacier. It should be noted there that the Tarim River basin is characterized by the extreme arid climate with an annual rainfall of less than 50 mm but the potential evaporation of more than 2,000 mm (Xu et al. 2004). Therefore, increasing temperature may cause increasing evaporation and which may cause decreasing loss of streamflow. Human activities, e.g. human withdrawal of water, irrigation, and so on, will further alter availability of water resource. Large-scale anthropogenic

9 Stoch Environ Res Risk Assess (2010) 24: activities such as agriculture irrigation and random reclamation in the upper and middle reaches of the Tarim River have triggered the disintegration of the natural hydrology (Tao et al. 2008). However, increasing precipitation in the headwater source, to a certain degree, may mitigate deficit of water resource in the Tarim River basin. This will definitely benefit the development of local agriculture activities. However, extensive agricultural activities caused increasing diversion of the freshwater to the new reclamation land. Therefore, the increasing streamflow in the headwater of the Tarim River basin may not satisfy the water demand of human activities, particularly the agricultural development, in the middle and lower Tarim River basin. Thus, it still calls for scientific, sound and effective water resource management on the river basin scale aiming to cater for the booming development of agriculture and fast population growth. Investigation on the relationship between climate changes and the availability of water resources is beneficial for the efficient water resources management (Bordi and Sutera 2001). The results of this paper may provide scientific framework for basin-scale water resource management and human mitigation to water resource variability under the changing environment in the Tarim River basin. Acknowledgments The work described in this paper was financially supported by the 985 Project (Grant No.: ), the innovative project from Nanjing Institute of Geography and Limnology, CAS (Grant No.: CXNIGLAS200814), National Scientific and Technological Support Program (Grant No.: 2007BAC03A0604), Key Laboratory of Oasis Ecology and Desert Environment, Xinjiang Institute of Ecology and Geography, CAS (Grant No.: ), and by Program of Introducing Talents of Discipline to Universities the 111 Project of Hohai University. Cordial thanks should be extended to the editor-in-chief, Prof. Dr. George Christakos and two anonymous reviewers for their constructive suggestions and comments which greatly helped to improve the quality of this paper. References Booij MJ (2005) Impact of climate change on river flooding assessed with different spatial model resolutions. J Hydrol 303: Bordi I, Sutera A (2001) Fifty years of precipitation: some spatially remote teleconnections. Water Resour Manag 15(4): Bosilovich MG, Schubert SD, Walker GK (2005) Global changes of the water cycle intensity. J Clim 18: Burn DH (2008) Climatic influences on streamflow timing in the headwaters of the Mackenzie River Basin. J Hydrol 352(1 2): Chen YN, Li WH, Chen YP, Zhang HF (2003) Water resources and ecological problems in Tarim River Basin, Xinjiang, China. In: Wilderer PA, Zhu J, Schwarzenbeck N (eds) Water and environmental management. IWA, London, pp 3 12 Chen YN, Takeuchi K, Xu C, Chen YP, Xu ZX (2006) Regional climate change and its effects on river runoff in the Tarim Basin, China. Hydrol Process 20: Chen H, Guo SL, Xu C-Y, Singh VP (2007) Historical temporal trends of hydro-climatic variables and runoff response to climate variability and their relevance in water resource management in the Hanjiang basin. J Hydrol 344(3-4): Douville H (2006) Impact of regional SST anomalies on the indian monsoon response to global warming in the CNRM climate model. J Clim 19(10): Douville H, Salas-Mélia D, Tyteca (2006) On the tropical origin of uncertainties in the global land precipitation response to global warming. Clim Dyn 26: Feng Q, Endo KN, Cheng GD (2001) Towards sustainable development of the environmentally degraded arid rivers of China-a case study from Tarim River. Environ Geol 4: Gao G, Chen D, Xu C-Y, Simelton E (2007) Trend of estimated actual evapotranspiration over China during J Geophys Res Atmos 112:D doi: /2006jd Hagg W, Braun LN, Kuhn M, Nesgaard TI (2007) Modelling of hydrological response to climate change in glacierized Central Asian catchments. J Hydrol 332:40 53 Houghton JT, Ding Y, Griggs DJ, Noguer M, van der Linden PJ, Dai X, Maskell K, Johnson CA (eds) (2001) Climate Change 2001: the scientific basis, third assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge Kendall MG (1975) Rank correlation methods. Griffin, London Khaled HH, Rao AR (1998) A modified Mann Kendall trend test for autocorrelated data. J Hydrol 204(1 4): Labat D, Goddéris Y, Probst JL, Guyot JL (2004) Evidence for global runoff increase related to climate warming. Adv Water Resour 27: Liu SY, Ding YJ, Shangguan DH (2006) Glacier retreat as a result of climate warming and increased precipitation in the Tarim River Basin, northwest China. Ann Glaciol 43:91 96 Mann HB (1945) Nonparametric tests against trend. Econometrica 13: Menzel L, Bürger G (2002) Climate change scenarios and runoff response in the Mulde catchment (Southern Elbe, Germany). J Hydrol 267:53 64 Mitchell JM, Dzerdzeevskii B, Flohn H, Hofmeyr WL, Lamb HH, Rao KN, Wallén CC (1966) Climate change, WMO Technical Note No. 79, World Meteorological Organization, pp 79 Shi YF, Shen YP, Li DL (2003) Transition from warm and dry climate to warm and humid climate in the north west China. Meteorological Press, Beijing (in Chinese) Shi YF, Liu SY, ShangGuan DH (2006) Two peculiar phenomena of climatic and glacial variations in the Tibetan Plateau. Adv Clim Change Res (in Chinese) 2(4): Song YD, Wang RH, Peng YS (2002) Water resources and ecological conditions in the Tarim. Sci China (Ser D) 45:11 17 Tao H, Marco G, Song YD, Su BD, Jiang T (2008) Eco-hydrological responses on water division in the lower reaches of the Tarim River, China. Water Resour Res 44:W doi: / 2007WR Xu C-Y, Singh VP (2004) Review on regional water resources assessment models under stationary and changing climate. Water Resour Manag 18: Xu Z, Chen Y, Li J (2004) Impact of climate change on water resources in the Tarim River basin. Water Resour Manag 18: Xu C-Y, Gong L, Jiang T, Chen D, Singh VP (2006) Analysis of spatial distribution and temporal trend of reference evapotranspiration in Changjiang (Yangtze River) catchment. J Hydrol 327:81 93 Ye M, Xu HL, Song YD (2006) Water resource and associate changing trends of the Tarim River basin. Chinese Sci Bull 51:14 20 (in Chinese) Yue S, Wang CY (2002) Applicability of prewhitening to eliminate the influence of serial correlation on the Mann Kendall test. Water Resour Res 38(6):1068. doi: /2001wr000861

10 358 Stoch Environ Res Risk Assess (2010) 24: Yue S, Wang CY (2004) The Mann Kendall test modified by effective sample size to detect trend in serially correlated hydrological series. Water Resour Manag 18: Zhang Q, Xu C-Y, Zhang Z, Chen YD, Liu C-L (2008a) Spatial and temporal variability of precipitation maxima during in the Yangtze River basin and possible association with largescale circulation. J Hydrol 353: Zhang Q, Xu C-Y, Gemmer M, Chen YD, Liu C-L (2008b) Changing properties of precipitation concentration in the Pearl River basin, China. Stoch Env Res Risk A 23(3): Zhang Q, Xu C-Y, Zhang Z, Chen YD (2008c) Changes of temperature extremes for in Far-West China. Stoch Environ Res Risk Assess. doi: /s