Changes in the Behavior of Long-Term Waterflow Variations in the Middle Part of Yakutia under the Global Warming Conditions

Abstract

Currently, not only the expected future climatic changes but also the associated changes in the long-term waterflow regime are popular research objectives. However, such studies, as a rule, are focused on large water bodies of a regional or even subplanetary significance. Also, the estimates obtained for the expected changes in the waterflow regime are of the most common nature. They are certainly important in terms of assumptions on the main trends in the development of the situation with water resources on a macro-regional scale but do little in assessing the risks of water use or even living safety (if people live near a water body) in the foreseeable future in respect of relatively small and medium-sized water bodies. The study identifies and evaluates the specifics of the waterflow regime response to global warming for rivers, the basins of which are compactly located within a single natural and climatic zone - the middle part of Yakutia. This approach allows adequately comparing the parameters of changes in the behavior of long-term waterflow variations for different rivers.For all rivers in the middle part of Yakutia, a significant increase in water content has been detected after 1987 (taken as the year preceding the start of the climate warming period), however, for the rivers of the western part of the region, this increase is associated not with a change in the behavior of long-term waterflow variations but with the onset of a high-water phase of a long-term natural cycle there. An increase in the annual waterflow variations was recorded for almost all rivers.Changes in the behavior of long-term waterflow variations after 1987 led to the loss of stationarity of the annual waterflow time series in the overwhelming majority of cases.It has been established that for rivers located in the middle part of Yakutia, a change in the behavior of long-term waterflow variations, which is presumably associated with global warming, can manifest itself in two main forms: a) in some cases, extremely high annual waterflow against the background of the typical regime of long-term variations - 1-2 cases (for the period from 1987 to 2018) lasting 1-3 years; b) the onset of a relatively long (5 years or more) period with an increased annual water content against the background of a violated of the cyclical behavior of long-term water content variations, which is typical for a given river. Herewith, for the rivers of the western region zone, the absence of pronounced changes in the behavior of long-term waterflow variations has been detected.