Optimisation of Water and Sand Flux Evolution and Monitoring in the Lower Reaches of the Yellow River Xiaolangdi Based on Multivariate Statistics and Time Series Analysis

In this paper, the water and sand monitoring data of a hydrological station in the lower reaches of Xiaolangdi of the Yellow River for the past 6 years are studied in depth based on multivariate statistics and time series analysis. By constructing multiple linear regression model, Pearson correlation analysis, sliding mean, fast Fourier transform (FFT) and SARIMA model, the relationship between sand content and water level and flow was systematically analysed, the sudden change, seasonal and cyclic characteristics of water-sand flux were revealed, and the water-sand flux in the next two years was predicted, and the optimised sampling and monitoring scheme was proposed. The results provide strong theoretical support and practical guidance for the scientific management and monitoring of water-sand fluxes in the lower reaches of the Yellow River, and help to improve the ecological management and resource allocation capacity of the Yellow River Basin. For the relationship between sand content, water level and flow at a hydrological station on the Yellow River, this paper establishes a multiple linear regression model and quantifies the relationship between the variables through Pearson correlation analysis. The results show that the flow rate is weakly and positively correlated with the sand content (Pearson correlation coefficient is about 0.25-0.3), and the water level has less influence on the sand content. The total annual water flow and total annual sand discharge at this hydrological station were further estimated from 2016 to 2021 using the time series aggregation method, with the total annual water flow fluctuating between 1.98 and 2.72 billion cubic metres (mcm), and the total annual sand discharge varying between 0.98 million tonnes (mt) and 1.95 million tonnes (mt). These results provide basic data support for subsequent water resource management and water-sand flux studies.