Changes in the mountain river discharge in the northern Tien Shan since the mid-20th Century: Results from the analysis of a homogeneous daily streamflow data set from seven catchments

This study is an assessment of the changes in seasonal and monthly flow in seven catchments draining the northern Tien Shan Mountains in Central Asia over a period from the 1950s to the present day. The purpose is to provide a first assessment of the flow response to climate change in regionally important catchments given their contribution to the water resource. All the catchments have a natural flow regime, and are therefore sensitive to climate change, but differ in area, elevation and glacial extent. Trends in flow were characterised using the Mann-Kendall test for standard meteorological seasons and individual months for mean flow, five flow quantiles and peak-over-threshold series for the period 1974–2013 at all sites and from the 1950s where data were available. The results were related to trends in seasonal temperature and precipitation from the regional high-elevation meteorological stations and glacier mass balance, equilibrium line altitude (ELA) and accumulation area ratio (AAR) records from the Tuyuksu glacier. The results show no reduction in streamflow in any catchment or season in the northern Tien Shan since the 1950s. Positive trends in all flow indicators, including peak-over-threshold frequency, were observed in catchments with higher glacierization of over 10% and extensive presence of rock glaciers and permafrost indicating increased melt over the period which is characterised by a long-term increase in temperature. These trends were most evident in autumn and winter. In catchments with low glacierization, variability in summer flow was controlled primarily by precipitation of the preceding cold season. Correlation with glacier mass balance was weak but changes in ELA and AAR indicate that production of liquid runoff at higher elevations contributes to increased streamflow partly compensating for the declining glacier area. The observed changes in streamflow do not suggest any immediate problems with water availability in the northern Tien Shan. On the contrary, increased autumn and winter flows point at a more prolonged recharge of reservoirs and aquifers though eventually this water source will be exhausted.

[1]  Andreas Kääb,et al.  On the response of rockglacier creep to surface temperature increase , 2007 .

[2]  Jérôme Le Coz,et al.  A literature review of methods for estimating the uncertainty associated with stage-discharge relations , 2012 .

[3]  Wilfried Hagg,et al.  Changes in glacierisation, climate and runoff in the second half of the 20th century in the Naryn basin, Central Asia , 2013 .

[4]  D. Viviroli,et al.  The hydrological significance of mountains: from regional to global scale , 2004 .

[5]  Douglas L. Kane,et al.  Siberian Lena River hydrologic regime and recent change , 2002 .

[6]  A. Bunde,et al.  LONG-TERM ANALYSIS OF AIR TEMPERATURE TRENDS IN CENTRAL ASIA 1) , 2007 .

[7]  M. Becht,et al.  Runoff modelling in glacierized Central Asian catchments for present-day and future climate , 2006 .

[8]  M. Dyurgerov,et al.  On the cause of glacier mass balance variations in the Tian Shan Mountains , 1994 .

[9]  Jun Qin,et al.  Recent climate changes over the Tibetan Plateau and their impacts on energy and water cycle: A review , 2014 .

[10]  J. Hannaford,et al.  Trends in seasonal river flow regimes in the UK , 2012 .

[11]  I. Severskiy,et al.  Changes in glaciation of the Balkhash–Alakol basin, central Asia, over recent decades , 2016, Annals of Glaciology.

[12]  P. Whitfield,et al.  Reference hydrologic networks II. Using reference hydrologic networks to assess climate-driven changes in streamflow , 2012 .

[13]  Peter Molnar,et al.  Streamflow trends in Switzerland , 2005 .

[14]  A. Bronstert,et al.  Attribution of high resolution streamflow trends in Western Austria - an approach based on climate and discharge station data , 2014 .

[15]  Jeff Dozier,et al.  Climatic and hydrologic changes in the Tien Shan, central Asia , 1997 .

[16]  Christoph Schär,et al.  The precipitation climate of Central Asia—intercomparison of observational and numerical data sources in a remote semiarid region , 2008 .

[17]  Martin Beniston,et al.  Climate change impacts on glaciers and runoff in Tien Shan (Central Asia) , 2012 .

[18]  T. Bolch.  Significance of glaciers, rockglaciers and ice-rich permafrost in the Northern Tien Shan as water towers under climate change conditions , 2006 .

[19]  S. Brönnimann,et al.  A guide for digitising manuscript climate data , 2006 .

[20]  Sheng Yue,et al.  The influence of autocorrelation on the ability to detect trend in hydrological series , 2002 .

[21]  H. Loáiciga,et al.  Simulation of daily runoff in Central Asian alpine watersheds , 2000 .

[22]  Harry Dixon,et al.  An appraisal of the performance of data-infilling methods for application to daily mean river flow records in the UK , 2012 .

[23]  A. Black,et al.  Re-assessing the flood risk in Scotland. , 2002, The Science of the total environment.

[24]  P. Micklin.  The Aral Sea Disaster , 2007 .

[25]  Paul H. Whitfield,et al.  Detection of runoff timing changes in pluvial, nival, and glacial rivers of western Canada , 2009 .

[26]  M. Kendall,et al.  Rank Correlation Methods , 1949 .

[27]  M. Bierkens,et al.  Comparison of climate change signals in CMIP3 and CMIP5 multi-model ensembles and implications for Central Asian glaciers , 2013 .

[28]  M. Cao.  Detection of abrupt changes in glacier mass balance in the Tien Shan Mountains , 1998, Journal of Glaciology.

[29]  R. Forthofer,et al.  Rank Correlation Methods , 1981 .

[30]  Maria Shahgedanova,et al.  The physical geography of northern Eurasia , 2002 .

[31]  John M. Melack,et al.  Precipitation, melt and runoff in the northern Tien Shan , 1996 .

[32]  P. Sen.  Estimates of the Regression Coefficient Based on Kendall's Tau , 1968 .

[33]  David N. Collins,et al.  Climatic fluctuations and runoff from glacierised Alpine basins , 1987 .

[34]  S. O’Neel,et al.  Glacierized headwater streams as aquifer recharge corridors, subarctic Alaska , 2017 .

[35]  Maria Shahgedanova,et al.  Glacier retreat and climatic variability in the eastern Terskey–Alatoo, inner Tien Shan between the middle of the 19th century and beginning of the 21st century , 2009 .

[36]  Yaning Chen,et al.  Review article: Hydrological modeling in glacierized catchments of central Asia – status and challenges , 2017 .

[37]  I. Severskiy,et al.  Assessment of Evolution of Mountain Lakes and Risks of Glacier Lake Outbursts in theDjungarskiy (Jetysu) Alatau, Central Asia, using Landsat Imagery and Glacier Bed TopographyModelling , 2017 .

[38]  Zbigniew W. Kundzewicz,et al.  Change detection in hydrological records—a review of the methodology / Revue méthodologique de la détection de changements dans les chroniques hydrologiques , 2004 .

[39]  Heiko Paeth,et al.  Dynamical downscaling of climate change in Central Asia , 2013 .

[40]  John Goodier,et al.  Encyclopedia of Snow, Ice and Glaciers , 2012 .

[41]  I. Severskiy,et al.  Assessment of evolution and risks of glacier lake outbursts in the Djungarskiy Alatau, Central Asia, using Landsat imagery and glacier bed topography modelling , 2017 .

[42]  Peter Bauer-Gottwein,et al.  Will climate change exacerbate water stress in Central Asia? , 2012, Climatic Change.

[43]  P. Whitfield.  Is ‘Centre of Volume’ a robust indicator of changes in snowmelt timing? , 2013 .

[44]  Donald H. Burn,et al.  Reference hydrologic networks I. The status and potential future directions of national reference hydrologic networks for detecting trends , 2012 .

[45]  H. Fowler,et al.  Elevation-dependent warming in mountain regions of the world , 2015 .

[46]  Bruno Merz,et al.  Analysis of current trends in climate parameters, river discharge and glaciers in the Aksu River basin (Central Asia) , 2015 .

[47]  Georg Kaser,et al.  Contribution potential of glaciers to water availability in different climate regimes , 2010, Proceedings of the National Academy of Sciences.

[48]  Vladimir E. Romanovsky,et al.  Permafrost warming in the Tien Shan Mountains, Central Asia , 2007 .

[49]  Bruno Merz,et al.  What do we know about past changes in the water cycle of Central Asian headwaters? A review , 2013 .

[50]  Bruno Merz,et al.  Attribution of streamflow trends in snow and glacier melt‐dominated catchments of the Tarim River, Central Asia , 2015 .

[51]  D. Stephenson,et al.  Observed Trends and Teleconnections of the Siberian High: A Recently Declining Center of Action , 2005 .

[52]  I. Otto,et al.  Climate change impacts in Central Asia and their implications for development , 2017, Regional Environmental Change.

[53]  Bruno Merz,et al.  Analysis of changes in climate and river discharge with focus on seasonal runoff predictability in the Aksu River Basin , 2014, Environmental Earth Sciences.

[54]  David J. Sauchyn,et al.  Increasing winter baseflow and mean annual streamflow from possible permafrost thawing in the Northwest Territories, Canada , 2009 .

[55]  Jamie Hannaford,et al.  Climate-driven changes in UK river flows , 2015 .

[56]  Robert L. Wilby,et al.  When and where might climate change be detectable in UK river flows? , 2006 .

[57]  T. Bolch,et al.  Region-wide glacier mass budgets and area changes for the Central Tien Shan between ~ 1975 and 1999 using Hexagon KH-9 imagery , 2015 .

[58]  Andreas Kääb,et al.  Spatial variability of recent glacier area changes in the Tien Shan Mountains, Central Asia, using Corona (~ 1970), Landsat (~ 2000), and ALOS (~ 2007) satellite data , 2010 .