Abstract:
The increasingly prominent contradiction between supply and demand of water resources under the changing environment has put forward higher requirements for the development and utilization of water resources in the river basin. By analyzing the characteristics of the runoff change in the basin, the evolution trend of the water resources in the watershed is revealed, which provides a scientific basis for the rational development and utilization of the water resources in the drainage basin. Taking the Weihe River basin (WRB) as the research area, the spatial and temporal variation characteristics, continuity and their relationships of the runoff measured at the six typical hydrological stations located along the mainstream of the WRB from 1956 to 2015 are analyzed by the methods of the fractal theory, Mann-Kendall non-parametric test and R/S analysis. The research results show that the monthly runoff measured by all hydrological stations in the Weihe River mainstream has decreasing trends. The significant decreasing trends of the monthly runoff become weaker, and the number of month with significant decreasing trends becomes less and less from the upstream to the downstream of the WRB. The Hurst index of the monthly runoff depth for all stations in the mainstream of the WRB is greater than 0.5. The results show that the future trends are positively correlated with those of the past, indicating that the monthly runoff will continue to decrease in the future. The fractal dimensions of the runoff during the flood season are larger than those of the non-flood season. The monthly runoff fractal dimensions of the upstream are smaller than those of the downstream, and the monthly runoff fractal dimensions in the middle reaches are the largest. The larger runoff fractal dimension represents the more complex runoff process and the worse regulation ability of the river. It is found that the adjustment ability of the runoff during the flood season in the middle reaches of the WRB mainstream is relatively poor. The Hurst index is significantly negatively correlated to the fractal dimension of the monthly runoff. That is, the more complex the runoff changes, the larger the fractal dimension and the smaller the Hurst index. The results can provide a basis for scientific operation of the water resources in the watershed and facilitate the strict management of the water resources in the basin.