Occurrence and Distribution of Long-Term Variability in Precipitation Classes in the Source Region of the Yangtze River

Abstract

Various precipitation-related studies have been conducted on the Yangtze River. However, the topography and atmospheric circulation regime of the Source Region of the Yangtze River (SRYZ) differ from other basin parts. Along with natural uniqueness, precipitation constitutes over 60% of the direct discharge in the SRYZ, which depicts the decisive role of precipitation and a necessary study on the verge of climate change. The study evaluates the event distribution of long-term variability in precipitation classes in the SRYZ. The precipitation was classified into three precipitation classes: light precipitation (0–5 mm, 5–10 mm), moderate precipitation (10–15 mm, 15–20 mm, 20–25 mm), and heavy precipitation (>25 mm). The year 1998 was detected as a changing year using the Pettitt test in the precipitation time series; therefore, the time series was divided into three scenarios: Scenario-R (1961–2016), the pre-change point (Scenario-I; 1961–1998), and the post-change point (Scenario-II; 1999–2016). Observed annual precipitation amounts in the SRYZ during Scenario-R and Scenario-I significantly increased by 13.63 mm/decade and 48.8 mm/decade, respectively. The same increasing trend was evident in seasonal periods. On a daily scale, light precipitation (0–5 mm) covered most of the days during the entire period, with rainy days accounting for 83.50%, 84.5%, and 81.30%. These rainy days received up to 40%, 41%, and 38% of the annual precipitation during Scenario-R, Scenario-I, and Scenario-II, respectively. Consequently, these key findings of the study will be helpful in basin-scale water resources management.

Channel morphological activation of large braided rivers in response to climate-driven water and sediment flux change in the Qinghai-Tibet Plateau

“…5). Air temperature and precipitation have increased significantly since 1990 and 2000 (Ahmed et al, 2023;Deng et al, 2022;Ji et al, 2021;Li et al, 2013aLi et al, , 2013bLi et al, , 2023b. It resulted in the increase of vegetation abundance and river channels after 2000 (Fig.…”

“…Annual precipitation increased by 44.3 mm in the 2000s and -8.7 mm in the 2010s (Fig. 5), this is the direct cause of runoff increase in the SRYR after 2000 (Ahmed et al, 2023;Wu et al, 2013). At the same time, the rising temperature causes the melting of glaciers and snow cover, and the change of permafrost active layer also promotes the recharge of discharge (Qi et al, 2015;Wang et al, 2009;Zhang et al, 2008).…”