Runoff variations in Lake Balkhash Basin, Central Asia, 1779-2015, inferred from tree rings

Panyushkina, Irina P. and Meko, D. M. and Macklin, M. G. and Toonen, W. H. J. and Mukhamadiev, N. S. and Konovalov, V. G. and Ashikbaev, N. Z. and Sagitov, A. O. (2018) Runoff variations in Lake Balkhash Basin, Central Asia, 1779-2015, inferred from tree rings. Climate Dynamics . ISSN 0930-7575

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Abstract

Long highly-resolved proxies for runoff are in high demand for hydrological forecasts and water management in arid Central Asia. An accurate (R2 = 0.53) reconstruction of October-September discharge of the Ili River in Kazakhstan, 1779–2015, is developed from moisture-sensitive tree rings of spruce sampled in the Tian Shan Mountains. The fivefold extension of the gauged discharge record represents the variability of runoff in the Lake Balkhash Basin for the last 235 years. The reconstruction shows a 40 year long interval of low discharge preceded a recent high peak in the first decade of the 2000s followed by a decline to more recent levels of discharge not seen since the start of the gauged record. Most reconstructed flow extremes (± 2σ) occur outside the instrumental record (1936–2015) and predate the start of large dam construction (1969). Decadal variability of the Ili discharge corresponds well with hydrological records of other Eurasian internal drainages modeled with tree rings. Spectral analysis identifies variance peaks (highest near 42 year) consistent with main hemispheric oscillations of the Eurasian climatic system. Seasonal comparison of the Ili discharge with sea-level-pressure and geopotential height data suggests periods of high flow likely result from the increased contribution of snow to runoff associated with the interaction of Arctic air circulation with the Siberian High-Pressure System and North Atlantic Oscillation.

Keywords:climate change impacts, water resources, lli River Runoff, discharge proxy, dendrochronology, picea schrenkiana, Tian Shan Mountains, Kazakhstan
Subjects:F Physical Sciences > F840 Physical Geography
F Physical Sciences > F810 Environmental Geography
Divisions:College of Science > School of Geography
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ID Code:30998
Deposited On:27 Feb 2018 09:58

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