PROGRESS IN GEOGRAPHY ›› 2015, Vol. 34 ›› Issue (9): 1148-1155.doi: 10.18306/dlkxjz.2015.09.007

• Orginal Article • Previous Articles     Next Articles

Response of river sediments to basin environmental changes:a case study of the Lancang River

Kaidao FU1,2(), Wenhui YANG1,2, Bin SU1,2, Daxing LI1,2, Mengyang LI3, Jilai ZHANG1,2, Jingyi SONG1,2   

  1. 1. Institute of International Rivers and Eco-security , Yunnan University, Kunming 650091, China
    2. Yunnan Key Laboratory of International Rivers and Transboundary Eco-security, Yunnan University, Kunming 650091, China
    3. Huaneng Lancang River Hydropower CO.,LTD., Kunming 650214, China
  • Online:2015-09-25 Published:2015-09-25

Abstract:

River sediments respond sensitively to the basin environmental changes and particle size parameters can reflect the hydrodynamic environment. This article takes the Lancang River as a case to explore the response of river sediment grain size to the basin environmental changes. River sediment samples were collected from 19 sections along the mainstream of the Lancang River, and sieving and pipette methods were applied to measure the particle size. Spatial and temporal variations of grain size parameters and their responses to the anthropogenic environmental changes of the basin through hydropower development were analyzed. Our results indicate that: (1) Spatially, the upstream of the Lancang River flows through the Tibet plateau region where the river valley is wide and flat, downward erosion is weak, and the sediments are characterized by small grain size and well sorted, with small kurtosis and negative skew or nearly symmetrical distributions; the middle part of the river flows through the alpine valleys, where the river flows fast, the grain size of bed sediments is coarse and poorly sorted, and the grain size distributions are more positively skewed with sharp kurtosis; in the lower reach of the river among the low and middle mountains and wide valleys sediment grain sizes are affected by the cascade dams, riverbed sediments' median and average grain sizes increased abruptly, especially the average grain sizes, with poorly sorted sediments, positively skewed grain size distribution and acute kurtosis. (2) On the temporal scale, grain sizes of sediments from different time periods indicate that the cascade dams increased the median and average grain sizes of the downstream sediments, especially the median increased dramatically. The sediments are poorly sorted, with positively skewed grain size distribution and acute kurtosis. The results accord with the normal pattern of distribution of sediment grain sizes in rivers, also reflect the impact of environmental changes on river sediment grain size composition.

Key words: river sediments, grain size, environmental change, hydropower development, the Lancang River