Does recent climate warming drive spatiotemporal shifts in functioning of high-elevation hydrological systems?

Area of Science:

• Hydrology
• Climatology
• Environmental Science

Background:

• Reference evapotranspiration (ETo) is a critical component of the hydrological cycle.
• Understanding ETo dynamics is vital for water resource management, especially in sensitive high-elevation regions like the Three-River Headwaters Region (TRHR).

Purpose of the Study:

• To systematically analyze the spatiotemporal variations of ETo in the TRHR from 1961 to 2016.
• To investigate the impact of key climatic variables on ETo fluctuations using sensitivity and contribution analyses.
• To provide insights into the physical mechanisms driving ETo changes for water resource management.

Main Methods:

• Utilized the FAO Penman-Monteith equation to calculate ETo.
• Conducted spatiotemporal variation analysis of ETo over a 56-year period.
• Employed sensitivity and contribution analyses to determine the influence of climatic variables (temperature, sunshine duration, humidity, wind speed) on ETo.

Main Results:

• Annual ETo showed an increasing trend in most regions of the TRHR over the study period.
• ETo exhibited distinct spatial distribution patterns, generally increasing from east to west, north to south, and with decreasing elevation.
• Maximum temperature and sunshine duration were identified as the most sensitive climatic variables affecting ETo, with rising temperatures being the primary contributor to increased ETo.

Conclusions:

• Significant temperature increases were the main driver of rising ETo in the TRHR.
• The study highlights a dominant altitudinal gradient in ETo sensitivity to climatic variables.
• Findings offer valuable references for water resource management and conservation strategies in high-elevation ecosystems.