A new complexity-based three-stage method to comprehensively quantify positive/negative contribution rates of climate change and human activities to changes in runoff in the upper Yellow River

Multiscale Analysis of Runoff Complexity in the Yanhe Watershed

“…Runoff variation in the hydrological system is affected by multiple factors. Climate change and human activities are two main driving factors that affect water cycles and the evolution of runoff in a watershed [ 17 ]. Studies have shown that meteorological factors have affected the runoff complexity of the Yellow River Basin, and precipitation has the greatest impact, followed by evaporation and temperature [ 17 , 45 ].…”

“…Climate change and human activities are two main driving factors that affect water cycles and the evolution of runoff in a watershed [ 17 ]. Studies have shown that meteorological factors have affected the runoff complexity of the Yellow River Basin, and precipitation has the greatest impact, followed by evaporation and temperature [ 17 , 45 ]. However, the literature and actual meteorological data do not indicate that meteorological factors underwent abrupt changes around 2010, which was the turning point of runoff complexity (see Figure 6 ).…”

“…By regarding the watershed system as a living organism, the concept that ‘life feeds on negative entropy’ has a profound impact on the study of natural systems [ 15 ]. Entropy methods have been widely used in evaluating the complexity of nonlinear and overall hydrological dynamics [ 11 , 16 , 17 ]. Sample entropy (SE) [ 18 ] quantifies the degree of regularity of a time series by evaluating the appearance of repetitive patterns, and has excellent stability and reliability in detecting the randomness and complexity of runoff [ 19 , 20 ].…”

“…Similarly, the runoff structure in hydrology also has its own complexity. The more complex the structure, the stronger the self-regulation and restoration ability, which usually means that the watershed is healthier [ 17 ]. In general, the original complexity of a hydrological system is close to the maximum that can occur with a long-term evolution of natural conditions, but it may lose its complexity and become an unhealthy watershed system because of human activities, such as soil and water conservation and construction of water conservancy projects [ 27 , 28 ].…”

An integrated assessment of runoff dynamics in the Amu Darya River Basin: Confronting climate change and multiple human activities, 1960–2017

“…Water resources are essential to the environment and society, however, with the impacts of climate and land-use changes, dam/reservoir construction, and unsustainable human water consumption, the water cycle has undergone rapid changes (Abbott et al, 2019). Some of the primary resulting manifestations are the spatio-temporal changes in hydrometeorological elements (Piao et al, 2010;Su et al, 2021) and the more frequent occurrence of extreme events (Duan et al, 2016;Trenberth et al, 2015). These can cause severe alterations in local ecosystems, such as vegetation degradation (Jiang et al, 2017;Zhou et al, 2019), soil salinization (Jiang et al, 2019;Zavialov et al, 2009), and soil erosion (Fang et al, 2013), particularly in arid areas.…”