Continuous Wetting on the Tibetan Plateau during 1970–2017

Huamin Zhang,Mingjun Ding,Linshan Liu,Lanhui Li

doi:10.3390/w11122605

Abstract

Based on daily observation records at 277 meteorological stations on the Tibetan Plateau (TP) and its surrounding areas during 1970–2017, drought evolution was investigated using the Standardized Precipitation Evapotranspiration Index (SPEI). First, the spatiotemporal changes in the growing season of SPEI (SPEIgs) were re-examined using the Mann–Kendall and Sen’s slope approach—the piecewise linear regression and intensity analysis approach. Then, the persistence of the SPEIgs trend was predicted by the Hurst exponent. The results showed that the SPEIgs on the TP exhibited a significant increasing trend at the rate of 0.10 decade−1 (p < 0.05) and that there is no significant trend shift in SPEIgs (p = 0.37), indicating that the TP tended to undergo continuous wetting during 1970–2017. In contrast, the areas surrounding the TP underwent a significant trend shift from an increase to a decrease in SPEIgs around 1984 (p < 0.05), resulting in a weak decreasing trend overall. Spatially, most of the stations on the TP were characterized by an increasing trend in SPEIgs, except those on the Eastern fringe of TP. The rate of drought/wet changes was relatively fast during the 1970s and 1980s, and gradually slowed afterward on the TP. Finally, the consistent increasing trend and decreasing trend of SPEIgs on the TP and the area East of the TP were predicted to continue in the future, respectively. Our results highlight that the TP experienced a significant continuous wetting trend in the growing season during 1970–2017, and this trend is likely to continue.

Highlights

Drought is recognized as one of the most destructive and expensive natural disasters in the world and has serious influences on agriculture, water resources, and human society [1,2]
This study re-examined the spatiotemporal evolution of drought in the growing season on the Tibetan Plateau (TP)
Its surrounding area during 1970–2017 using Standardized Precipitation Evapotranspiration Index (SPEI) with potential evapotranspiration estimated by the Penman–Monteith equation

Summary

Introduction

Drought is recognized as one of the most destructive and expensive natural disasters in the world and has serious influences on agriculture, water resources, and human society [1,2]. In the context of global warming, increasing drought has been observed over much of the global land area and has resulted in increased drought losses [3,4]. Annual drought losses have been above 200 billion dollars worldwide since 1960 [5]. Global warming is projected to enhance droughts in the current century [6], and drought losses are expected to continue to soar in the future [7]. Given that drought exerts complex spatial and temporal heterogeneity, a better understanding of the occurrence and evolution of drought will increase our ability to manage drought risk and reduce drought losses. In the past several decades, a variety of multivariate drought indices have been developed for meteorological drought detection and monitoring, such as the Standardized Precipitation Index (SPI) [8]

Objectives

Methods

Results

Discussion

Conclusion