258 / 2024-02-28 19:00:42

Research on Trends of Hydrological Regimes in the middle and lower reaches of the Yalong River Basin Based on IHA Indicators with Trend Analysis Technology

hydrological regime; IHA indicator; univariate and multivariate M-K trend analysis; MASH-Sen method; Yalong River

With the development of the society and economy, cascade reservoirs have been constructed along the river for meeting various purposes of hydroelectricity, flood control, irrigation and water supply. In the meanwhile, the operation of cascade reservoirs may influence the natural hydrological regime. Over ten reservoirs have been built or planned to build in the middle and lower reaches of the Yalong River, which have been formed into the third largest hydropower base in China. To analyze trend changes of hydrological regimes in the Yalong River basin, this study selected daily runoff data from 1959 to 2019 at the Yajiang, Luning and Tongzilin hydrological stations and calculated their values of IHA indicators. Univariate and multivariate M-K trend tests were applied to analyze the trends of IHA indicators and the MASH-Sen method was implemented to investigate inter- and intra-annual trend of daily runoff data. The results showed that: (1) there were significant increasing trends in the IHA indicators related to the non-flood seasons at the Yajiang hydrological station, 18 IHA indicators and joint indicators at the Luning hydrological station showed significant decreasing trends and there are increasing and decreasing trends in the IHA indicators related to the non-flood seasons and flood seasons at the Tongzilin hydrological station; (2) the MASH-Sen method could simultaneously analyze inter- and intra- annual trends of the runoff, which is complementary to the trend analysis of IHA indicators in daily runoff, and there are decreasing trends in runoff especially from 1995-2014 to 2000-2019 filtered by MASH at the Luning hydrological station. This study can provide references on optimizing cascade reservoir operation for alleviating the impact on the natural hydrological regime of the Yalong River basin.