scholarly journals Anthropogenic and Climate Effects on a Free Dam Tropical River: Measuring the Contributions on Flow Regime

2020 ◽  
Vol 12 (23) ◽  
pp. 10030
Author(s):  
Verônica Léo ◽  
Hersília Santos ◽  
Letícia Pereira ◽  
Lilia Oliveira
Keyword(s):  
Climate Change ◽  
Flow Regime ◽  
River Flow ◽  
Human Impacts ◽  
Global Climate ◽  
Rate Of Change ◽  
Hydrologic Alteration ◽  
Tropical River ◽  
Range Of Variability Approach ◽  
Flow Components

The demand for freshwater resources and climate change pose a simultaneous threat to rivers. Those impacts are often analyzed separately, and some human impacts are widely evaluated in river dynamics—especially in downstream areas rather than the consequences of land cover changes in headwater reaches. The distinction between anthropogenic and climate on the components of the flow regime is proposed here for an upstream free dam reach whose watershed is responsible for the water supply in Rio de Janeiro. Indicators of hydrologic alteration (IHA) and the range of variability approach (RVA) combined with statistical analyses of anthropogenic and climate parameters indicated that (1) four river flow components (magnitude, frequency, duration, and rate of change) were greatly altered from the previous period (1947 to 1967) and the actual (1994 to 2014); (2) shifts in the sea surface temperature of the Atlantic correlated with flow magnitude; (3) the cattle activity effects on the flow regime of the studied area decreased 42.6% of superficial discharge; global climate change led to a 10.8% reduction in the same river component. This research indicated that climate change will impact the intensification of human actions on rivers in the southeast Brazilian headwaters.

scholarly journals Potential impacts to freshwater ecosystems caused by flow regime alteration under changing climate conditions in Taiwan

2008 ◽  
Vol 5 (6) ◽  
pp. 3005-3032 ◽  
Author(s):  
J.-P. Suen
Keyword(s):  
Climate Change ◽  
Flow Regime ◽  
River Flow ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Climate Conditions ◽  
Regime Changes ◽  
Changing Climate ◽  
Extreme Flood ◽  
Precautionary Measures

Abstract. Observed increases in the Earth's surface temperature bring with them associated changes in precipitation and atmospheric moisture that consequentially alter river flow regimes. This paper uses the Indicators of Hydrologic Alteration approach to examine climate-induced flow regime changes that can potentially affect freshwater ecosystems. Analyses of the annual extreme water conditions at 23 gauging stations throughout Taiwan reveal large alterations in recent years; extreme flood and drought events were more frequent in the period after 1991 than from 1961–1990, and the frequency and duration of the flood and drought events also show high fluctuation. Climate change forecasts suggest that such flow regime alterations are going to continue into the foreseeable future. Aquatic organisms not only feel the effects of anthropogenic damage to river systems, but they also face on-going threats of thermal and flow regime alterations associated with climate change. This paper calls attention to the issue, so that water resources managers can take precautionary measures that reduce the cumulative effects from anthropogenic influence and changing climate conditions.

scholarly journals Future evolution and uncertainty of river flow regime change in a deglaciating river basin

2019 ◽  
Vol 23 (4) ◽  
pp. 1833-1865 ◽  
Author(s):  
Jonathan D. Mackay ◽  
Nicholas E. Barrand ◽  
David M. Hannah ◽  
Stefan Krause ◽  
Christopher R. Jackson ◽  
...  
Keyword(s):  
Climate Change ◽  
Flow Regime ◽  
River Basin ◽  
River Flow ◽  
Climate Model ◽  
Emission Scenario ◽  
Numerical Models ◽  
Ice Melt ◽  
Model Chain ◽  
Runoff Routing

Abstract. The flow regimes of glacier-fed rivers are sensitive to climate change due to strong climate–cryosphere–hydrosphere interactions. Previous modelling studies have projected changes in annual and seasonal flow magnitude but neglect other changes in river flow regime that also have socio-economic and environmental impacts. This study employs a signature-based analysis of climate change impacts on the river flow regime for the deglaciating Virkisá river basin in southern Iceland. Twenty-five metrics (signatures) are derived from 21st century projections of river flow time series to evaluate changes in different characteristics (magnitude, timing and variability) of river flow regime over sub-daily to decadal timescales. The projections are produced by a model chain that links numerical models of climate and glacio-hydrology. Five components of the model chain are perturbed to represent their uncertainty including the emission scenario, numerical climate model, downscaling procedure, snow/ice melt model and runoff-routing model. The results show that the magnitude, timing and variability of glacier-fed river flows over a range of timescales will change in response to climate change. For most signatures there is high confidence in the direction of change, but the magnitude is uncertain. A decomposition of the projection uncertainties using analysis of variance (ANOVA) shows that all five perturbed model chain components contribute to projection uncertainty, but their relative contributions vary across the signatures of river flow. For example, the numerical climate model is the dominant source of uncertainty for projections of high-magnitude, quick-release flows, while the runoff-routing model is most important for signatures related to low-magnitude, slow-release flows. The emission scenario dominates mean monthly flow projection uncertainty, but during the transition from the cold to melt season (April and May) the snow/ice melt model contributes up to 23 % of projection uncertainty. Signature-based decompositions of projection uncertainty can be used to better design impact studies to provide more robust projections.

scholarly journals New Methods for the Assessment of Flow Regime Alteration under Climate Change and Human Disturbance

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2435
Author(s):  
Pengfei Shi ◽  
Jiahong Liu ◽  
Tao Yang ◽  
Chong-Yu Xu ◽  
Jie Feng ◽  
...  
Keyword(s):  
Climate Change ◽  
Flow Regime ◽  
Yellow River ◽  
Anthropogenic Activities ◽  
Great Influence ◽  
Time Warping ◽  
New Methods ◽  
Range Of Variability Approach ◽  
Dynamic Time ◽  
High Level

Climate change and anthropogenic activities do collectively lead to an alteration of the flow regime, posing a great influence upon the structure and persistence of native biotic communities within river ecosystems. The range of variability approach (RVA) method is commonly used to evaluate the flow regime alteration. However, it was reported to underestimate the degree of flow regime potentially. In this study, two new assessment methods/metrics for evaluating the process behaviors of the flow regime are developed based on Euclidean distance and dynamic time warping (DTW) distance. They are then integrated with the metric of RVA, generating two composite metrics that represent both frequency and process changes of the flow regime. The new methods/metrics were applied to identify the flow regime alteration in a typical basin in the middle reaches of the Yellow River, China. The results show that the composite metrics consistently reveal a high alteration degree of flow regime in the basin. The decreased biological integrity of fish demonstrates the reasonability of the high-level overall alteration to some degree. The updated methods enable more scientific evaluation for the complex hydrologic alteration under a changing environment.

scholarly journals Calibration of hydrological models for ecologically relevant streamflow predictions: a trade-off between fitting well to data and estimating consistent parameter sets?

2020 ◽  
Vol 24 (3) ◽  
pp. 1031-1054 ◽  
Author(s):  
Thibault Hallouin ◽  
Michael Bruen ◽  
Fiachra E. O'Loughlin
Keyword(s):  
Flow Regime ◽  
River Flow ◽  
Freshwater Ecosystems ◽  
Living Environment ◽  
Rate Of Change ◽  
Low Flow ◽  
Hydrological Models ◽  
Flow Conditions ◽  
Local Flow ◽  
Trade Off

Abstract. The ecological integrity of freshwater ecosystems is intimately linked to natural fluctuations in the river flow regime. In catchments with little human-induced alterations of the flow regime (e.g. abstractions and regulations), existing hydrological models can be used to predict changes in the local flow regime to assess any changes in its rivers' living environment for endemic species. However, hydrological models are traditionally calibrated to give a good general fit to observed hydrographs, e.g. using criteria such as the Nash–Sutcliffe efficiency (NSE) or the Kling–Gupta efficiency (KGE). Much ecological research has shown that aquatic species respond to a range of specific characteristics of the hydrograph, including magnitude, frequency, duration, timing, and the rate of change of flow events. This study investigates the performance of specially developed and tailored criteria formed from combinations of those specific streamflow characteristics (SFCs) found to be ecologically relevant in previous ecohydrological studies. These are compared with the more traditional Kling–Gupta criterion for 33 Irish catchments. A split-sample test with a rolling window is applied to reduce the influence on the conclusions of differences between the calibration and evaluation periods. These tailored criteria are shown to be marginally better suited to predicting the targeted streamflow characteristics; however, traditional criteria are more robust and produce more consistent behavioural parameter sets, suggesting a trade-off between model performance and model parameter consistency when predicting specific streamflow characteristics. Analysis of the fitting to each of 165 streamflow characteristics revealed a general lack of versatility for criteria with a strong focus on low-flow conditions, especially in predicting high-flow conditions. On the other hand, the Kling–Gupta efficiency applied to the square root of flow values performs as well as two sets of tailored criteria across the 165 streamflow characteristics. These findings suggest that traditional composite criteria such as the Kling–Gupta efficiency may still be preferable over tailored criteria for the prediction of streamflow characteristics, when robustness and consistency are important.

Will human impacts on Alpine geomorphic processes scale up to the depositional record?

2020 ◽  
Author(s):  
Stuart Lane
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Human Activities ◽  
Human Impacts ◽  
Global Climate ◽  
Sediment Flux ◽  
Earth System ◽  
Human Response ◽  
Sediment Sources ◽  
Geomorphic Processes

<p>The Anthropocene is widely described as producing a rupture in the global stratigraphic signature, attributable to human activities. There is no doubt that human activities have introduced new products into the stratigraphic record; and that humans are modifying the geomorphic processes that produce the sediment which then becomes incorporated into that record. The stratigraphic literature is replete with simplistic generalisations of how sediment flux to the continental shelf is changing, such as increasing due to soil erosion or decreasing due to hydropower related sediment flux disconnection. Here we argue that human impacts on geomorphic processes in the Anthropocene are unlikely to be stationary for long enough for them to be seen consistently across the depositional record of many different environments. Illustrating this for a major inner-Alpine drainage basin, the Swiss Rhône, we show that human-driven global climate-change is indeed dramatically altering the geomorphic process regimes of Alpine environments. However, there are three broad reasons why this is unlikely to be seen in the future geological record. First, the geomorphic response that drives increased sediment delivery is transient because of the significant regime changes associated with global climate change impacts. Second, such increases are countered by other human impacts, notably those on sediment flux, which are tending to reduce the connectivity of sediment sources to downstream sediment sinks. Third, human impacts on both sediment sources and connectivity are nonstationary, driven by both exogenous factors (here illustrated by the worldwide economic shock of 2008) and endogenous ones, notably human response to the perceived problems caused by both sediment starvation and sediment over-supply. In geomorphic terms, then, there is a difference between the pervasive nature of Earth system shifts that we see in the pre-Holocene depositional record and the more ephemeral impacts of the Earth system – human coupling associated with the Anthropocene. The extent to which this is the case is likely to vary geographically and temporally as a function of the degree and nature of human impacts on geomorphic processes. Thus, the primary challenge for future prediction will be as much the prediction of the complex and reflexive nature of human response as it will be geomorphic processes themselves.</p>

scholarly journals The impact of river regulation in the Tigris and Euphrates on the Arvandroud Estuary

2020 ◽  
Vol 44 (6) ◽  
pp. 948-970 ◽  
Author(s):  
Ali Torabi Haghighi ◽  
Mojtaba Sadegh ◽  
Joy Bhattacharjee ◽  
Mehmet Emin Sönmez ◽  
Mojtaba Noury ◽  
...  
Keyword(s):  
Flow Regime ◽  
Iraq War ◽  
River Flow ◽  
Remote Sensing Data ◽  
River Regulation ◽  
Rate Of Change ◽  
The Past ◽  
New Information ◽  
Flow Changes ◽  
The Impact

The Arvandroud river (also known as Shatt-al-Arab) and its estuary have been degraded due to the changing river flow regime in the Tigris and Euphrates. This study assessed changes in flow from the major rivers and the impacts on the estuary. To assess the river flow changes, three major flow regime attributes were computed: timing (TIF), magnitude (MIF), and variability (VIF). By combining these indices, the total flow regime impact factor (IF) was scaled between 0 and 1, and classified into five groups: Low (0.80<IF<1.0), Incipient (0.60<IF<0.80), Moderate (0.40<IF<0.60), Severe (0.2<IF<0.40), and Drastic (0.0<IF<0.20). Flow regime impact maps were then created for 1941–1955, 1960–1970, 1975–1984, and 1990–2000. These revealed that, over time, the impact has extended along the basin from downstream to upstream, with a significant flow regime change from 1941–1955 to 1990–2000 in the Tigris, Euphrates, and Arvandroud. Analysis of remote sensing data revealed that the change in the flow regime has led to land degradation in the Arvandroud estuary during the past 46 years (1972–2018). In addition, the impact of the Iran–Iraq war (based on degradation of vegetation cover between 1985 and 1988) is 5.1 times of mean rate of change during 1972–2018. This study thus contributes new information on estuaries and the impact of upstream land and water use change.

scholarly journals Variations of Mass Balance of the Greenland Ice Sheet from 2002 to 2019

2020 ◽  
Vol 12 (16) ◽  
pp. 2609
Author(s):  
Yaqiong Mu ◽  
Yanqiang Wei ◽  
Jinkui Wu ◽  
Yongjian Ding ◽  
Donghui Shangguan ◽  
...  
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Quantitative Research ◽  
Global Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Rate Of Change ◽  
Ice Caps ◽  
Ice Cap ◽  
Temperature And Precipitation

The melting of the polar ice caps is considered to be an essential factor for global sea-level rise and has received significant attention. Quantitative research on ice cap mass changes is critical in global climate change. In this study, GRACE JPL RL06 data under the Mascon scheme based on the dynamic method were used. Greenland, which is highly sensitive to climate change, was selected as the study area. Greenland was divided into six sub-research regions, according to its watersheds. The spatial–temporal mass changes were compared to corresponding temperature and precipitation statistics to analyze the relationship between changes in ice sheet mass and climate change. The results show that: (i) From February 2002 to September 2019, the rate of change in the Greenland Ice Sheet mass was about −263 ± 13 Gt yr−1 and the areas with the most substantial ice sheet loss and climate changes were concentrated in the western and southern parts of Greenland. (ii) The mass balance of the Greenland Ice Sheet during the study period was at a loss, and this was closely related to increasing trends in temperature and precipitation. (iii) In the coastal areas of western and southern Greenland, the rate of mass change has accelerated significantly, mainly because of climate change.

Stability of River Flow Regimes

1992 ◽  
Vol 23 (3) ◽  
pp. 137-154 ◽  
Author(s):  
I. Krasovskaia ◽  
L. Gottschalk
Keyword(s):  
Climate Change ◽  
Flow Regime ◽  
Climate Models ◽  
River Flow ◽  
Flow Regimes ◽  
Low Flow ◽  
Future Climate Change ◽  
Mean Annual Temperature ◽  
Economic Policies ◽  
Temperature And Precipitation

One of the most important consequences of future climate change may be an alteration of the surface hydrological balance, including changes in flow regimes, i.e. seasonal distribution of flow and especially the time of occurrence of high/low flow, which is of vital importance for environmental and economic policies. Classification of flow regimes still has an important role for the analyses of hydrological response to climate change as well as for validating climate models on present climatic and hydrologic data, however, with some modifications in the methodology. In this paper an approach for flow regime classification is developed in this context. Different ways of flow regime classification are discussed. The stability of flow regimes is studied in relation to changes in mean annual temperature and precipitation. The analyses have shown that even rather small changes in these variables can cause changes in river flow regimes. Different patterns of response have been traced for different regions of the Nordic countries.

Sign in / Sign up

Export Citation Format

Share Document