Climate Change Shows Obvious Impacts on Hydrological Processes, Multiple Uncertainty Sources Quantification Verifies

A recent study using two uncertainty sources quantification methods extracting 504 simulation combination of different uncertainty factors showed strong evidence that the global climate change have obvious impact on the hydrological processes.

The study, led by CHEN Yaning, a researcher with the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences, was published on the latest issue of Hydrology Research.

Climate change has seen 16 of the 17 warmest years on record occurred since 2001. The global average sea level has risen nearly 178mm over the past 100 years, about 3.4 mm per year.

Scientific evidence has proved that climate changes will produce an effect on the hydrologic balance and water resources. Recent hydrological research suggests that “greenhouse effect” will alter the timing and magnitude of runoff and soil moisture, change lake levels, and affect water quality.

“Quantifying the uncertainty sources in assessment of climate change impacts on hydrological processes is helpful for local water management decision-making,” said CHEN.

However, previous studies have been arguing on the uncertainty of different sources such as climate model, emission circumstances, downscaling, and hydrological models.

CHEN and his team investigated the impact of the general circulation model (GCM) structural uncertainty on hydrological processes in the Kaidu River Basin of northwestern China’s Xinjiang province, with two uncertainty sources quantification methods.

The team combined 21 climate models, two emission scenarios, four precipitation downscaling methods, three temperature downscaling methods, and one hydrological models, and formed 504 simulations for their uncertainty sources quantification.

Their results show that the precipitation will increase by 3.1%–18% under medium emission scenario of RCP (Representative Concentration Pathways) 4.5, and the temperature will increase by 2.0 °C–3.3 °C. The streamflow will change by −26% to 3.4% accordingly.

When it comes to RCP8.5, a higher emission scenario, the precipitation will raise to7.0%–22.5%, with the temperature increase by 4.2 °C–5.5 °C and the streamflow −38% to −7%.

Timing of snowmelt will shift forward by approximately one to two months for both scenarios.

The study was published with the title of Impact of GCM structure uncertainty on hydrological processes in an arid area of China 

on recent issue of Hydrology of Research.