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A Five-century Streamflow Reconstruction from China

Paper Reviewed
Yang, Y., Chen, Y., Wang, M. and Sun, H. 2017. Reconstruction and analysis of the past five centuries of streamflow on northern slopes on Tianshan Mountains in Northern Xinjiang, China. Theoretical and Applied Climatology 129: 177-184.

Introducing their study, Yang et al. (2017) report that modern instrumental stream gauge records are generally too short for investigating variations in the regional hydrological cycle because they do not contain "the full range of durations and magnitudes of droughts that have occurred in the past." Researchers thus turn to proxy climate records from which they can view and study such oscillations to better understand the frequency and magnitude of natural climate variability, which understanding is critical in climate change attribution studies that seek to determine the magnitude and extent of an anthropogenic influence (most commonly associated with CO2-induced global warming).

As their contribution to the subject, Yang et al. utilized tree-ring records from Schrenk spruce (Picea schrenkiana) trees, coupled with meteorological data, to derive a 500-year reconstruction of streamflow in the Tianshan Mountains of northern Xinjiang, China. This reconstruction is depicted in the figure below.

With respect to their record, Yang et al. report that streamflow has "undergone many periods of both low and high flow" (defined as streamflow more/less than the mean plus/minus half the standard deviation). However, they state that "these periods have been short, which illustrates the stable variation of the streamflow." Put another way, there appears to be nothing unusual, unnatural or unprecedented about this streamflow record, which appears to have regularly oscillated between periods of above- and below-average flow, keeping within the realm of natural variability.

Figure 1. Reconstructed 5-year running average of streamflow in northing Xinjiang over the past five centuries. Adapted from Yang et al. (2017).

Posted 20 December 2017