Long-term trends in global river flow and the causal relationships between river flow and ocean signals

Su, Lei; Miao, Chiyuan; Kong, Dongxian; Duan, Qingyun; Lei, Xiaohui; Hou, Qianqian; Li, Hu

doi:10.1016/j.jhydrol.2018.06.058

Cited by 65 publications

(39 citation statements)

References 90 publications

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“…The latter interpretation is consistent with the results of a large-scale study of trends in the flow of 916 world's largest rivers by Su et al (2018). The results, and specifically those in their Table 1 that take into account the long-term persistence, show some trends, either positive (3.7% of the rivers) or negative (8.2% of the rivers).…”

Section: Is Quite Indicative: 460supporting

confidence: 88%

Revisiting global hydrological cycle: Is it intensifying?

Koutsoyiannis¹

2020

Preprint

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Abstract. As a result of technological advances in monitoring atmosphere, hydrosphere, cryosphere and biosphere, as well as in data management and processing, several data bases have become freely available. These can be exploited in revisiting the global hydrological cycle with the aim, on the one hand, to better quantify it and, on the other hand, to test the established climatological hypotheses, according to which the hydrological cycle should be intensifying because of global warming. By processing the information from gridded ground observations, satellite data and reanalyses, it turns out that the established hypotheses are not confirmed. Instead of monotonic trends, there appear fluctuations from intensification to deintensification and vice versa, with deintensification prevailing in the 21st century. The water balance on land and sea appears to be lower than the standard figures of literature, but with greater variability on climatic time scales, which is in accordance with Hurst-Kolmogorov stochastic dynamics. The most obvious anthropogenic signal in the hydrological cycle appears to be the overexploitation of groundwater, which has a visible effect on sea level rise. Melting of glaciers has an equal effect, but in this case it in not known which part is anthropogenic, as studies on polar regions attribute mass loss mostly to ice dynamics.

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Section: Is Quite Indicative: 460supporting

confidence: 88%

Revisiting global hydrological cycle: Is it intensifying?

Koutsoyiannis¹

2020

Preprint

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“…For example, decreased river runoff may in some cases be directly attributed to anthropogenic activities within the river catchment. These activities may be the building of dams and reservoirs, but also land use changes (agriculture, forestry), urbanization, structural changes to shoreline or the extraction of water for irrigation purposes (Figures 1G,H) (Milliman et al, 2008;García-Ruiz et al, 2011;Su et al, 2018). Within midlatitude rivers for example, river runoff has decreased by ∼60% during the last half of the 20th century (Milliman et al, 2008).…”

Section: Global Cases Caused By Structural Modificationsmentioning

confidence: 99%

Reevaluating the Role of Organic Matter Sources for Coastal Eutrophication, Oligotrophication, and Ecosystem Health

Deininger

Frigstad

2019

Front. Mar. Sci.

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Organic matter (OM) in aquatic systems is either produced internally (autochthonous OM) or delivered from the terrestrial environment (ter-OM). For eutrophication (or the reverse-oligotrophication), the amount of autochthonous OM plays a key role for coastal ecosystem health. However, the influence of ter-OM on eutrophication or oligotrophication processes of coastal ecosystems is largely unclear. Therefore, ter-OM, or ter-OM proxies are currently not included in most policies or monitoring programs on eutrophication. Nevertheless, ter-OM is increasingly recognized as a strong driver of aquatic productivity: By influencing underwater light conditions and nutrient-and carbon availability, increased ter-OM input may shift systems from autotrophic toward heterotrophic production, but also alter the interactions between benthic, and pelagic habitats. Thus, by changing baseline conditions in coastal zones, ongoing, and predicted changes in inputs of ter-OM due to climate change (e.g., in precipitation) and anthropogenic activities (e.g., reduced sulfate deposition, damming, and coastal erosion) may strongly modify eutrophication symptoms within affected ecosystems, but also hinder recovery from eutrophication following a reduction in nutrient loadings (i.e., oligotrophication). In this review, we aim to shed light upon the role of ter-OM for coastal eutrophication and oligotrophication processes and ecosystem health. Specifically, we (1) discuss the theoretical interactions between ter-OM and eutrophication and oligotrophication processes in coastal waters, (2) present global case studies where altered ter-OM supply to coastal ecosystems has shifted baseline conditions, with implications for eutrophication and oligotrophication processes, and (3) provide an outlook and recommendations for the future management of coastal zones given changes in ter-OM input. We conclude that it is essential to include and target all OM sources (i.e., also ter-OM) in monitoring programs to better understand the consequences of both eutrophication and oligotrophication processes on coastal ecosystems. Our review strongly urges to include ter-OM, or ter-OM proxies in eutrophication monitoring, and policies to safeguard coastal ecosystem health also under changing climatic conditions and globally increasing anthropogenic perturbations of coastal ecosystems.

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“…For a better understanding of these changes and for effective managing of water resources, hydro-meteorological investigations in river watersheds have been carried out around the world. However, most of these studies focused rather on a large watershed scale due to the data availability [13,14]. In contrast, not much research has been devoted to small watersheds, in which there is a shortage of long-term datasets [15] that are needed for climate impact studies [16].…”

Section: Introductionmentioning

confidence: 99%

Long-Term Changes of Hydrological Variables in a Small Lowland Watershed in Central Poland

Krajewski

Sikorska‐Senoner

Ranzi

et al. 2019

Water

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Climate-induced changes in small watersheds are still not well researched because long-term datasets are usually missing for these watersheds. Such studies can, however, improve our understanding of the watershed response to climatic changes at such a small scale being transparent. In this study, we investigate trends in temperature, precipitation and river-flow characteristics in a small watershed, typical for Central Poland, with 53 years of observations (1963–2015) using the Mann-Kendall test. Particularly, we examine whether any trends in hydro-meteorological variables can be identified, and if any associated changes in water resources in this region can already be observed. We found that this short period already allows for detecting some changes in hydro-meteorological variables. These changes could be characterized by a significant increase in the mean annual air temperature on a daily basis, and a significant decrease in the mean annual discharge on a daily basis and in the minimum annual discharge on a daily basis. Yet, no significant trend could be detected for the total annual precipitation, the maximum summer rainfall, and the maximum annual discharge on a daily basis. These findings indicate that water resources are decreasing in this region, which affects natural habitats, agriculture and local communities.

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Long-term trends in global river flow and the causal relationships between river flow and ocean signals

Cited by 65 publications

References 90 publications

Revisiting global hydrological cycle: Is it intensifying?

Revisiting global hydrological cycle: Is it intensifying?

Reevaluating the Role of Organic Matter Sources for Coastal Eutrophication, Oligotrophication, and Ecosystem Health

Long-Term Changes of Hydrological Variables in a Small Lowland Watershed in Central Poland

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