Changes in Magnitude and Timing of High Flows in Large Rain-Dominated Watersheds in the Cold Region of North-Eastern China

Liangliang Duan,Tijiu Cai

doi:10.3390/w10111658

Abstract

Global warming-induced earlier streamflow timing and changes in flood risk have been widely reported in snow-dominated regions where the land surface hydrology is dominated by winter snow accumulation and spring melt. However, impacts of climate warming on flow regime in the cold regions dominated by monsoonal rain during the warm season have received little attention in the literature. In this study, the responses of magnitude and timing of high flows to climate warming were analyzed by using a paired-year approach based on the hydrometeorological data of two large rain-dominated watersheds in the cold region of north-eastern China in the past approximately four decades (1975–2013). The results indicated that high flow timings of two watersheds both exhibited significant negative trends associated with the significant increasing trends in air temperature and spring rain over the study period. The results from paired-year approach indicated average timings of high flows in the warming years were significantly advanced by 21 and 25 days in Upper Huma River (UHR) and Ganhe River (GR) watersheds, respectively, which was at least partly attributed to the more frequent occurrence of spring snowmelt/rain generated high flows because of climate warming-induced earlier snowmelt and increased spring rain. The average magnitude of high flows decreased by 13.7% and 14.0% in the warming years compared with those in the reference years in the UHR and GR watersheds, respectively. These findings have implications for water resource management in the study region and similar rain-dominated cold regions across the globe.

Highlights

Nature flow regimes pertaining to the characteristic pattern of a river’s flow quantity, timing, and variability create and maintain the dynamics of in-channel and floodplain habitats that play a critical role in sustaining native biodiversity and ecosystem integrity in rivers [1,2]
There are a large number of studies showing that climate warming has the potential to modify nature flow regimes [3,4], especially in the snow-dominated regions where the water supply mainly depends on the seasonal snowpack that was likely to be materially affected by global warming in the past half century [5,6]
Our results from the paired-year approach indicated that both study watersheds exhibited timings of high flows in the warming years compared with those in the reference years

Summary

Introduction

Nature flow regimes pertaining to the characteristic pattern of a river’s flow quantity, timing, and variability create and maintain the dynamics of in-channel and floodplain habitats that play a critical role in sustaining native biodiversity and ecosystem integrity in rivers [1,2]. There are a large number of studies showing that climate warming has the potential to modify nature flow regimes [3,4], especially in the snow-dominated regions where the water supply mainly depends on the seasonal snowpack that was likely to be materially affected by global warming in the past half century [5,6]. There is evidence of reductions in snow cover extent and earlier snowmelt in spring in many part of the northern hemisphere [7], and the changing snowfall pattern has in turn affected the spatial and temporal distribution of streamflow over much of the global land area poleward of about. Changes towards earlier streamflow timing due to climate warming were found in snowmelt-dominated regions in the western North America [12], in eastern North America [13], in Spain [14] and in Chile [15].

Methods

Results

Discussion

Conclusion