Abstract
Hydrological extremes are closely related to extreme hydrological events, which have been and continue to be one of the most important natural hazards causing great damage to lives and properties. As two of the main factors affecting the hydrological cycle, land-use change and climate change have attracted the attention of many researchers in recent years. However, there are few studies that comprehensively consider the impacts of land-use change and climate change on hydrological extremes, and few researchers have made a quantitative distinction between them. Regarding this problem, this study aims to quantitatively distinguish the effects of land-use change and climate change on hydrological extremes during the past half century using the method of scenarios simulation with the soil and water assessment tool (SWAT). Furthermore, the variations of hydrological extremes are forecast under future scenarios by incorporating the downscaled climate simulations from several representative general circulation models (GCMs). Results show that: (1) respectively rising and declining risks of floods and droughts are detected during 1960–2017. The land use changed little during 1980–2015, except for the water body and building land. (2) The SWAT model possesses better simulation effects on high flows compared with low flows. Besides, the downscaled GCM data can simulate the mean values of runoff well, and acceptable simulation effects are achieved for the extreme runoff indicators, with the exception of frequency and durations of floods and extreme low flows. (3) During the period 1970–2017, the land-use change exerts little impact on runoff extremes, while climate change is one of the main factors leading to changes in extreme hydrological situation. (4) In the context of global climate change, the indicators of 3-day max and 3-day min runoff will probably increase in the near future (2021–2050) compared with the historical period (1970–2005). This research helps us to better meet the challenge of probably increased flood risks by providing references to the decision making of prevention and mitigation measures, and thus possesses significant social and economic value.
Highlights
In recent years, hydrological responses in a changing environment have become a research hotspot [1,2,3]
The inverse distance weighting (IDW) method is one of the most commonly used techniques for the interpolation of scatter points, which is based on the concept of distance weighting
The trends and variations of extreme hydro-meteorological elements as well as the land-use changes in the Jinsha River Basin have been thoroughly investigated during the historical period
Summary
Hydrological responses in a changing environment have become a research hotspot [1,2,3]. As the major factors affecting hydrological processes, land-use change and climate change have been given much attention [4,5,6,7]. Increasingly frequent extreme hydrological events have become an important area of research due to their strong destructive power [8,9,10]. Regarding land-use change, this is the other critical factor influencing rainfall-runoff processes by affecting surface runoff components, such as evapotranspiration and infiltration. The analysis and prediction of hydrological extremes under land-use change and climate change are of great importance for the prevention and mitigation of hydrological disasters
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