Changing low flow seasonality in Central European headwaters

2021 ◽  
Author(s):  
Vojtech Vlach ◽  
Ondrej Ledvinka ◽  
Milada Matouskova
Keyword(s):  
Flow Regime ◽  
R Package ◽  
Hydrological Drought ◽  
Low Flow ◽  
Significant Shift ◽  
Regime Changes ◽  
Seasonality Index ◽  
Long Term Trends ◽  
Summer Minimum ◽  
Hydrological Droughts

<p>In the environment of the changing climate in Central Europe, the seasonality and magnitude of low flow events and hydrological droughts are projected to change in the near future. Ongoing increases in the air temperature, rates of evaporation and decreasing snow cover will significantly affect the summer deficit volumes even in the rivers of humid montane and highland areas in mid-latitudes. However, what if the significant changes have already been happening during the last decades? Therefore, this research is focused on analysis of the variability and seasonality of low flow events and hydrological drought events in fifteen near-natural catchments along the Czech–German and Czech–Polish national borders. To quantify the low flow regime changes of the study regions in the last 52 years (1968–2019), we applied tools from the R package lfstat. The 30-year moving averages of seasonality ratio (SR) and the seasonality index (SI) were derived to address the degree of change in each catchment. Moreover, the 7-day and 30-day mean summer minimum discharges were computed, as well as the streamflow deficit volumes for every episode of hydrological drought. The results showed a continual increase in the proportion of summer low flow and drought events during the study period along with a significant shift in the average date of low flow occurrence towards the beginning of the year. The most marked shifts in low flow seasonality were found mainly in catchments with the average altitude 800–1000 m a. s. l. Conversely, the low flow regime in catchments above 1000 m a. s. l. and also in the catchments below 800 m a. s. l. remained nearly stable throughout the 1968–2019 period. Moreover, the analysis of 7- and 30-day mean summer minimum discharges indicated a much-diversified pattern in the behavior of long-term trends than it was expected.</p>

scholarly journals Changing Low Flow and Streamflow Drought Seasonality in Central European Headwaters

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3575
Author(s):  
Vojtech Vlach ◽  
Ondrej Ledvinka ◽  
Milada Matouskova
Keyword(s):  
Kendall Test ◽  
R Package ◽  
Low Flow ◽  
Headwater Catchments ◽  
Low Flows ◽  
Seasonality Index ◽  
Apparent Shift ◽  
Summer Minimum ◽  
Increasing Temperature

In the context of the ongoing climate warming in Europe, the seasonality and magnitudes of low flows and streamflow droughts are expected to change in the future. Increasing temperature and evaporation rates, stagnating precipitation amounts and decreasing snow cover will probably further intensify the summer streamflow deficits. This study analyzed the long-term variability and seasonality of low flows and streamflow droughts in fifteen headwater catchments of three regions within Central Europe. To quantify the changes in the low flow regime of selected catchments during the 1968–2019 period, we applied the R package lfstat for computing the seasonality ratio (SR), the seasonality index (SI), mean annual minima, as well as for the detection of streamflow drought events along with deficit volumes. Trend analysis of summer minimum discharges was performed using the Mann–Kendall test. Our results showed a substantial increase in the proportion of summer low flows during the analyzed period, accompanied with an apparent shift in the average date of low flow occurrence towards the start of the year. The most pronounced seasonality shifts were found predominantly in catchments with the mean altitude 800–1000 m.a.s.l. in all study regions. In contrast, the regime of low flows in catchments with terrain above 1000 m.a.s.l. remained nearly stable throughout the 1968–2019 period. Moreover, the analysis of mean summer minimum discharges indicated a much-diversified pattern in behavior of long-term trends than it might have been expected. The findings of this study may help identify the potentially most vulnerable near-natural headwater catchments facing worsening summer water scarcity.

scholarly journals Study On the Driven Mechanism of Watershed Hydrological Drought Based on Geomorphological Spatial Distribution Pattern: A Case Study of Guizhou, China

2021 ◽  
Author(s):  
Zhonghua he ◽  
Hong Liang ◽  
Zhaohui Yang
Keyword(s):  
Annual Variation ◽  
Hydrological Drought ◽  
Guizhou Province ◽  
Low Flow ◽  
Drought Severity ◽  
The North ◽  
Driving Mechanisms ◽  
Hydrologic Drought ◽  
Hydrological Droughts

Abstract In recent years, hydrological drought has become more and more frequent, which has caused serious ecological and environmental problems. This paper is taking Guizhou province of China as an example to analyze the geomorphologic distribution and temporal-spatial evolution of hydrological droughts, and to study driving mechanisms of both the rainfall in the dry periods and geomorphologic factor on the hydrological droughts, based on the hydrometeorological data during the years 2000-2010, and the TM and DEM data. The results show that (1) the rainfall and its variation in the low-flow seasons have less impacts on the hydrologic drought and its variation; (2) the hydrologic drought severity in Guizhou was increasing year by year during the years 2000-2010, and showing the inter-annual variation with obvious stage characteristics, and the regional hydrologic drought was presented the more serious in the South than in the North, and the less serious in the East than in the West; and (3) in terms of the overall distribution of landform types, the mountain, hill and basin have less impacts on hydrological droughts; in terms of the distribution of single geomorphic type, hydrological droughts are significantly influenced by the high-medium mountain, deep-high hill and high basin, where the hydrological droughts are relatively lighter. While there are more serious areas in the low basin, shallow-low hill and low mountain.

scholarly journals Analyzing Changes in the Flow Regime of the Yangtze River Using the Eco-Flow Metrics and IHA Metrics

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1552 ◽  
Author(s):  
Bing Gao ◽  
Jie Li ◽  
Xiaoshu Wang
Keyword(s):  
Flow Regime ◽  
Reservoir Operation ◽  
Yangtze River ◽  
Main Channel ◽  
Climate Variation ◽  
Low Flow ◽  
Distributed Hydrological Model ◽  
The Yangtze River ◽  
Regime Changes ◽  
Precipitation Decrease

Changes in the flow regime of the Yangtze River were investigated using an efficient framework that combined the eco-flow metrics (ecosurplus and ecodeficit) and Indicators of Hydrologic Alteration (IHA) metrics. A distributed hydrological model was used to simulate the natural flow regime and quantitatively separate the impacts of reservoir operation and climate variation on flow regime changes. The results showed that the flow regime changed significantly between the pre-dam and post-dam periods in the main channel and major tributaries. Autumn streamflow significantly decreased in the main channel and in the tributaries of the upper Yangtze River, as a result of a precipitation decrease and reservoir water storage. The release of water from reservoirs to support flood regulation resulted in a significant increase in winter streamflow in the main channel and in the Minjiang, Wujiang, and Hanjiang tributaries. Reservoir operation and climate variation caused a significant reduction in low flow pulse duration in the middle reach of the Yangtze River. Reservoir operation also led to an increase in the frequency of low flow pulses, an increase in the frequency of flow variation and a decrease in the rate of rising flow in most of the tributaries. An earlier annual minimum flow date was detected in the middle and lower reaches of the Yangtze River due to reservoir operation. This study provides a methodology that can be implemented to assess flow regime changes caused by dam construction in other large catchments.

Spatiotemporal Clustering of Hydrological Droughts in Peninsular India

2021 ◽  
Author(s):  
Poulomi Ganguli ◽  
Bhupinderjeet Singh ◽  
Aparna Raut
Keyword(s):  
Central India ◽  
Climate Extremes ◽  
Hydrological Drought ◽  
Low Flow ◽  
Monsoon Period ◽  
Peninsular India ◽  
Variable Threshold ◽  
Daily Streamflow ◽  
Multi Stage ◽  
Hydrological Droughts

<p>Drought is considered one of the costliest climate extremes that have wide impacts on humans and ecosystems. Understanding different drought stages, for example, onset, propagation, and its recovery, especially for tropical (the vulnerable region in Earth’s climate system) catchments are crucial for ecosystem sustainability and food security. Utilizing gauge-based quality-controlled daily streamflow records from 98 catchments of rain-fed Peninsular River Basins (PRB) in India, here we investigate different phases of hydrological droughts in a multi-stage framework. While several studies so far have investigated the propagation of hydrological droughts at a monthly resolution, a credible understanding of drought dynamics requires analyzing low-flow series at a higher spatial and temporal resolution, ensuring the issuance of timely alerts related to regional water scarcity.  Owing to high seasonality in the daily streamflow records, a variable threshold approach is adopted to delineate streamflow-based drought events. To assess the temporal evolution of droughts, the events are categorized into various inter-related phases, i.e., growth, persistence, and recovery stage over the study period 1965 – 2018. For most of the gauges, the mean timing of drought onset mostly lies between August and September revealing failure of monsoon as the primary causal factor for drought development in peninsular catchments. Furthering this, we identify four distinct hydrological drought regimes, which includes, <strong>Regime 1:</strong> persistent droughts with longer duration and moderate deficit volume with average termination during mid-monsoon (in September). These gauges are mostly situated in Central India and typically show a longer recovery time coincided with shorter return times (i.e., the time between two consecutive drought events), making it one of the most vulnerable regions in PRB; <strong>Regime 2:</strong> droughts with a shorter duration, least deficit volume with average termination in October, the post-monsoon period. These gauges are located in the western part of the country; <strong>Regime 3:</strong> droughts with the highest variability in drought deficit volume with the largest subsurface contribution from groundwater recharge. These sites are primarily located in eastern India and do not show any specific trend in the termination period; <strong>Regime 4:</strong> droughts with least regularity in drought termination with the average termination month clustered around November. These gauges are mostly concentrated in the southwestern part of the country. Our findings add value to the systematic understanding of hydrological drought propagations in rain-fed catchments, which serves as a basis for exploring future changes in droughts under concurrent shifts in rainfall and temperature extremes in a warming climate. </p>

scholarly journals The European 2015 drought from a hydrological perspective

2017 ◽  
Vol 21 (6) ◽  
pp. 3001-3024 ◽  
Author(s):  
Gregor Laaha ◽  
Tobias Gauster ◽  
Lena M. Tallaksen ◽  
Jean-Philippe Vidal ◽  
Kerstin Stahl ◽  
...  
Keyword(s):  
Water Cycle ◽  
Hydrological Drought ◽  
Low Flow ◽  
Drought Indices ◽  
Climate Indices ◽  
Climate Data ◽  
Spatial And Temporal Scales ◽  
Space And Time ◽  
Dynamic Development ◽  
The Difference

Abstract. In 2015 large parts of Europe were affected by drought. In this paper, we analyze the hydrological footprint (dynamic development over space and time) of the drought of 2015 in terms of both severity (magnitude) and spatial extent and compare it to the extreme drought of 2003. Analyses are based on a range of low flow and hydrological drought indices derived for about 800 streamflow records across Europe, collected in a community effort based on a common protocol. We compare the hydrological footprints of both events with the meteorological footprints, in order to learn from similarities and differences of both perspectives and to draw conclusions for drought management. The region affected by hydrological drought in 2015 differed somewhat from the drought of 2003, with its center located more towards eastern Europe. In terms of low flow magnitude, a region surrounding the Czech Republic was the most affected, with summer low flows that exhibited return intervals of 100 years and more. In terms of deficit volumes, the geographical center of the event was in southern Germany, where the drought lasted a particularly long time. A detailed spatial and temporal assessment of the 2015 event showed that the particular behavior in these regions was partly a result of diverging wetness preconditions in the studied catchments. Extreme droughts emerged where preconditions were particularly dry. In regions with wet preconditions, low flow events developed later and tended to be less severe. For both the 2003 and 2015 events, the onset of the hydrological drought was well correlated with the lowest flow recorded during the event (low flow magnitude), pointing towards a potential for early warning of the severity of streamflow drought. Time series of monthly drought indices (both streamflow- and climate-based indices) showed that meteorological and hydrological events developed differently in space and time, both in terms of extent and severity (magnitude). These results emphasize that drought is a hazard which leaves different footprints on the various components of the water cycle at different spatial and temporal scales. The difference in the dynamic development of meteorological and hydrological drought also implies that impacts on various water-use sectors and river ecology cannot be informed by climate indices alone. Thus, an assessment of drought impacts on water resources requires hydrological data in addition to drought indices based solely on climate data. The transboundary scale of the event also suggests that additional efforts need to be undertaken to make timely pan-European hydrological assessments more operational in the future.

scholarly journals Alluvial evidence for major climate and flow regime changes during the middle and late Quaternary in eastern central Australia

Geomorphology ◽  
2008 ◽  
Vol 101 (1-2) ◽  
pp. 109-129 ◽  
Author(s):  
Gerald C. Nanson ◽  
David M. Price ◽  
Brian G. Jones ◽  
Jerry C. Maroulis ◽  
Maria Coleman ◽  
...  
Keyword(s):  
Flow Regime ◽  
Late Quaternary ◽  
Regime Changes ◽  
Central Australia

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 Spatial development of hydrological droughts in lake catchments

2019 ◽  
Vol 19 (4) ◽  
pp. 159-174
Author(s):  
Malwina Kozek ◽  
Edmund Tomaszewski
Keyword(s):  
Spatial Development ◽  
Hydrological Drought ◽  
Stream Network ◽  
Area Increase ◽  
Daily Discharge ◽  
Maximum Flows ◽  
Balance Structure ◽  
Lake Systems ◽  
Hydrological Droughts ◽  
Basin Area

AbstractIn river-lake systems, reservoirs significantly affect the formation of water resources in the catchment by reducing the maximum flows and floods as well as increasing the low flows. In lake catchments, the pace of hydrological drought progression is usually slow. However, this phenomenon can be very extreme and destructive for water balance structure as a result of the very slow renewal rate of catchment resources. An estimation of hydrological drought development was conducted in the Biebrza river catchment (6,900 km2) on the basis of a daily discharge series for 18 water-gauge stations in the period 1982–2014. The number and location of the gauges allowed reliable results of the spatial pattern of drought to be obtained. The main objective of the research was the construction and assessment of the applicability of indicators which are estimators of drought spatial progression. Comparative analysis of four proposed indices led to two of them being recommended. These characteristics estimate the direction of drought development according to the stream network hierarchy, location of sub-catchments and the direction of river basin area increase. As a result, determinants of the spatial development of hydrological drought as well as its importance in the hydrographical structure were identified. Furthermore, the intensity of drought was evaluated and all investigated indices were applied to a time series analysis.

scholarly journals Hydrological Drought Regimes of the Huai River Basin, China: Probabilistic Behavior, Causes and Implications

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2390 ◽  
Author(s):  
Sun ◽  
Zhang ◽  
Yao ◽  
Wen
Keyword(s):  
River Basin ◽  
Hydrological Drought ◽  
Drought Severity ◽  
Copula Functions ◽  
Drought Duration ◽  
Huai River Basin ◽  
Huai River ◽  
The Impact ◽  
Hydrological Droughts ◽  
The Huai River Basin

: Hydrological droughts were characterized using the run-length theory and the AIC (Akaike information criterion) techniques were accepted to evaluate the modeling performance of nine probability functions. In addition, the copula functions were used to describe joint probability behaviors of drought duration and drought severity for the major tributaries of the Huai River Basin (HRB) which is located in the transitional zone between humid and semi-humid climates. The results indicated that: (1) the frequency of hydrological droughts in the upper HRB is higher than that in the central HRB, while the duration of the hydrological drought is in reverse spatial pattern. The drought frequency across the Shiguan River along the south bank of the HRB is higher than the other two tributaries; (2) generalized Pareto distribution is the appropriate distribution function with the best performance in modelling the drought duration over the HRB; while the Generalized Extreme Value (GEV) distribution can effectively describe the probabilistic properties of the drought severity. Joe copula and Tawn copula functions are the best choices and were used in this study. Given return periods of droughts of <30 years, the droughts in the upper HRB are the longest, and the shortest are in the central HRB; (3) the frequency of droughts along the mainstream of the HRB is higher than tributaries of the HRB. However, concurrence probability of droughts along the mainstream of the HRB is lower than the tributaries of the HRB. The drought resistance capacity of HRB has been significantly improved, effectively reducing the impact of hydrological drought on crops after 2010.

Sign in / Sign up

Export Citation Format

Share Document