Is eastern Mongolia drying? A long-term perspective of a multidecadal trend

Abstract

Temperatures in semiarid Mongolia have rapidly risen over the past few decades, and increases in drought, urban development, mining, and agriculture have intensified demands on limited water resources. Understanding long-term streamflow variation is critical for Mongolia, particularly if alterations in streamflow are being considered and because of the potential negative impacts of drought on the animal agriculture sector. Here, we present a temporally and spatially improved streamflow reconstruction for the Kherlen River. We have added 11 new records in comparison with two in the original 2001 reconstruction. This new reconstruction extends from 1630 to 2007 and places the most recent droughts in a multicentennial perspective. We find that variations in streamflow have been much greater in the past than in the original study. There was higher variability in the mid to late 1700s, ranging from severe and extended drought conditions from 1723 to 1739 and again in 1768–1778 to two decadal length episodes of very wet conditions in the mid 1700s and late 1700s. Reduced amplitude is seen in the mid-1800s, and several pluvial events are reconstructed for the 1900s. Although recent droughts are severe and disturbing economic and ecological systems in Mongolia and it appears that eastern Mongolia is drying, the drying trend since the late 1900s might in fact be accentuated by a change from a particularly wet era in Mongolia. The recent drought might be a return to more characteristic hydroclimatic conditions of the past four centuries in Mongolia