Recent Changes of Water Discharge and Sediment Load in the Buyuan River Basin, China

Abstract

Changes in stream flow and sediment load in the Buyuan River Basin is a focus due to its vital ecological niche in supply feeding and spawning habitats for upstream migrant fish species of Mekong River. Based on the precipitation and water discharge series data (19592008), and sediment load series data (19932008), the runoff and sediment discharge variation and its response to precipitation has been analyzed. The results shown that, during the study period of 19592008 at the Manan gauging station, annual runoff of Buyuan River has generally decreased, but not significant at the 95% confidence level. However, the decline trend of sediment load was obvious for gauged period from 1993 to 2008. The seasonal runoff distribution in the Buyuan River was uneven and demonstrated an observably unimodal distribution. Both water discharge and sediment load are largely derived from wet season (from Jun to Nov), especially in flood season from July to September. During the study period 1993-2008, both annual and monthly observed value of water discharge and sediment load had coincident changing processes. Double mass curves indicated decreasing precipitation was the main reason for runoff reduction in the Buyuan River Basin; declining rainfall and water discharge were two key factors for sediment load reduction. In 2002, however, sediment discharge undergone abrupt change due to huge peak discharge and two consecutive years strong precipitation in the Buyuan River Basin.

Runoff responses to climate change in China's Buyuan River Basin

“…The Buyuan River, located between 21°40 N–23°08 N and 100°52 E–101°40 E, spans the cities of Pu'er and Xishuangbanna in Yunnan Province and has a total length of 370 km, while the total catchment area of the basin is 7679 km 2 (Zhong et al, 2013). The climate of the BRB can be classified as subtropical monsoon with an average annual temperature and precipitation of 21.5°C and 1488 mm, respectively, with the rainy season extending from June to November.…”

“…Several studies have analyzed the runoff variation trend of the BRB in the past decades. The majority of these studies focused on the temporal and spatial distribution of the runoff and the potential impacts of changes in the runoff (Bi, Zhao, Xiao, Zhou, & Zhang, 2015; Jiang, Wang, Shen, Lu, & Ni, 2019; Liu, Liu, Lu, Duan, & Li, 2011; Yu, Pan, Liu, Chen, & He, 2017; Zhong, He, & Fu, 2013). Most of these studies used statistical methods to analyze the observed data, which directly reflect the changes in hydrological factors, but it is difficult to analyze the impact of future climate change on the runoff.…”