Abstract
As one of the most common natural phenomena, floods can bring both risks and benefits for human beings. They can pose a risk of inundation to a human habitat but can also be utilized as a resource with hydraulic engineering. Improving the knowledge of flood characteristics is the basis and premise of improving water resources management and ecological environmental protection. Presently, the quantitative evaluation of flood characteristics needs to gradually evolve from a single indicator to a systematic one. In this paper, by introducing the concepts of ecohydrology on magnitude, frequency, and duration, a set of flood characteristics indicators evaluation system is constructed based on the hydrological characteristics for the section where Danjiangkou Reservoir is located at the middle reach of the Yangtze in China. The results showed that the Danjiangkou Reservoir has changed the flood characteristics to a great extent both of seasonal or annual floods, and the mean degree of the flood characteristic alteration indicators is about 19%. The changing trend of the flood indicators upstream showed an increasing trend from the 1970s to 2010s, while downstream were divided into two periods by the year of about 1975. The methodological system provided by this paper can effectively evaluate flood characteristics quantitatively, provide technical guidance and a useful reference for flood process analysis, and provide support for flood management and river ecosystem protection.
Highlights
The results showed that all the average values for the indicators of the post-operation period were smaller than the preoperation, but the coefficient of variation (CV) values became larger
We need to consider more factors including rainfall, spatial patterns, geomorphology, and other characteristics, but for a single water conservancy project, its attention should be focused on the flooding process, and the indicators can be customized components according to the actual situation in the framework of the system proposed in this study
This paper systematically studied the flood alteration of Danjiangkou Reservoir by constructing quantitative indicators of flood characteristics using the Histogram Matching Approach (HMA) and multiple trend analysis methods, which can provide a reference for a deeper understanding of flood changes under the influence of hydraulic engineering
Summary
With the dual impact of climate change and human activities [1,2], the flood regimes of many large rivers around the world have changed significantly [3,4,5]; this has had a profound impact on regional flood control safety, water resources utilization, ecological protection, etc It is of great scientific importance how to describe floods objectively. Some studies have combined meteorological and hydrological elements to establish some simplified indicators for characterizing flood processes, such as monthly rainfall [16], rainy season rainfall [17], maximum daily annual floods, and precipitation [18,19] These indicators are well-adapted to the disciplines of water resources engineering, flood frequency analysis, and project impact evaluation. Such quantitative indicators and methods for evaluation and analysis for the variation of flood characteristics [20,21] still has limitations, mainly in which the indicators are too singular and do not constitute a system, can just reflect an aspect of flood characteristic and it is difficult to fully reflect the characteristics of floods
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