scholarly journals From meteorological to hydrological drought using standardised indicators

2016 ◽  
Vol 20 (6) ◽  
pp. 2483-2505 ◽  
Author(s):  
Lucy J. Barker ◽  
Jamie Hannaford ◽  
Andrew Chiverton ◽  
Cecilia Svensson
Keyword(s):  
Time Series ◽  
Hydrological Drought ◽  
Annual Rainfall ◽  
Strongly Correlated ◽  
Propagation Characteristics ◽  
The South ◽  
Drought Characteristics ◽  
The North ◽  
The Uk ◽  
Hydrological Droughts

Abstract. Drought monitoring and early warning (M & EW) systems are a crucial component of drought preparedness. M & EW systems typically make use of drought indicators such as the Standardised Precipitation Index (SPI), but such indicators are not widely used in the UK. More generally, such tools have not been well developed for hydrological (i.e. streamflow) drought. To fill these research gaps, this paper characterises meteorological and hydrological droughts, and the propagation from one to the other, using the SPI and the related Standardised Streamflow Index (SSI), with the objective of improving understanding of the drought hazard in the UK. SPI and SSI time series were calculated for 121 near-natural catchments in the UK for accumulation periods of 1–24 months. From these time series, drought events were identified and for each event, the duration and severity were calculated. The relationship between meteorological and hydrological drought was examined by cross-correlating the 1-month SSI with various SPI accumulation periods. Finally, the influence of climate and catchment properties on the hydrological drought characteristics and propagation was investigated. Results showed that at short accumulation periods meteorological drought characteristics showed little spatial variability, whilst hydrological drought characteristics showed fewer but longer and more severe droughts in the south and east than in the north and west of the UK. Propagation characteristics showed a similar spatial pattern with catchments underlain by productive aquifers, mostly in the south and east, having longer SPI accumulation periods strongly correlated with the 1-month SSI. For catchments in the north and west of the UK, which typically have little catchment storage, standard-period average annual rainfall was strongly correlated with hydrological drought and propagation characteristics. However, in the south and east, catchment properties describing storage (such as base flow index, the percentage of highly productive fractured rock and typical soil wetness) were more influential on hydrological drought characteristics. This knowledge forms a basis for more informed application of standardised indicators in the UK in the future, which could aid in the development of improved M & EW systems. Given the lack of studies applying standardised indicators to hydrological droughts, and the diversity of catchment types encompassed here, the findings could prove valuable for enhancing the hydrological aspects of drought M & EW systems in both the UK and elsewhere.

scholarly journals From meteorological to hydrological drought using standardised indicators

2015 ◽  
Vol 12 (12) ◽  
pp. 12827-12875 ◽  
Author(s):  
L. J. Barker ◽  
J. Hannaford ◽  
A. Chiverton ◽  
C. Svensson
Keyword(s):  
Time Series ◽  
Hydrological Drought ◽  
Strongly Correlated ◽  
Propagation Characteristics ◽  
The South ◽  
Drought Characteristics ◽  
The North ◽  
The One ◽  
The Uk ◽  
Hydrological Droughts

Abstract. Drought monitoring and early warning (M&EW) systems are a crucial component of drought preparedness. M&EW systems typically make use of drought indicators such as the Standardised Precipitation Index (SPI), but such indicators are not widely used in the UK. More generally, such tools have not been well developed for hydrological (i.e. streamflow) drought. To fill these research gaps, this paper characterises meteorological and hydrological droughts, and the propagation from one to the other using the SPI and the related Standardised Streamflow Index (SSI), with the objective of improving understanding of the drought hazard in the UK. SPI and SSI time series were calculated for 121 near-natural catchments in the UK for accumulation periods of 1–24 months. From these time series, drought events were identified and for each event, the duration and severity was calculated. The relationship between meteorological and hydrological drought was examined by cross-correlating the one month SSI with various SPI accumulation periods. Finally, the influence of climate and catchment properties on the drought characteristics and propagation were investigated. Results showed that at short accumulation periods meteorological drought characteristics showed little spatial variability, whilst hydrological drought characteristics showed fewer but longer and more severe droughts in the south and east than in the north and west of the UK. Propagation characteristics showed a similar spatial pattern with catchments underlain by productive aquifers, mostly in the south and east, having longer SPI accumulation periods strongly correlated with the one-month SSI. For catchments in the north and west of the UK, which typically have little catchment storage, standard-period annual average rainfall was strongly correlated to drought and propagation characteristics. However, in the south and east, catchment properties describing storage, such as base flow index, percentage of highly productive fractured rock and typical soil wetness, were more influential on drought characteristics. This knowledge forms a basis for more informed application of standardised indicators in the UK in future, which could aid in the development of improved M&EW systems. Given the paucity of studies applying standardised indicators to hydrological droughts, and the diversity of catchment types encompassed here, the findings could prove valuable for enhancing the hydrological aspects of M&EW systems elsewhere in the world.

Climatology and Trends of Climate Extremes of Temperature and Precipitation in Belo Monte Hydropower Plant – Eastern Amazon, Brazil

2021 ◽  
Author(s):  
Wanderson Luiz-Silva ◽  
Pedro Regoto ◽  
Camila Ferreira de Vasconcellos ◽  
Felipe Bevilaqua Foldes Guimarães ◽  
Katia Cristina Garcia
Keyword(s):  
Climate Change ◽  
Climate Extremes ◽  
Annual Rainfall ◽  
The South ◽  
North Central ◽  
Adaptation Capacity ◽  
The North ◽  
South Central ◽  
Daily Data ◽  
Belo Monte

<p>This research aims to support studies related to the adaptation capacity of the Amazon region to climate change. The Belo Monte Hydroelectric Power Plant (HPP) is in the Xingu River basin, in eastern Amazonia. Deforestation coupled with changes in water bodies that occurred in the drainage area of Belo Monte HPP over the past few decades can significantly influence the hydroclimatic features and, consequently, ecosystems and energy generation in the region. In this context, we analyze the climatology and trends of climate extremes in this area. The climate information comes from daily data in grid points of 0.25° x 0.25° for the period 1980-2013, available in http://careyking.com/data-downloads/. A set of 17 climate extremes indices based on daily data of maximum temperature (TX), minimum temperature (TN), and precipitation (PRCP) was calculated through the RClimDex software, recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI). The Mann-Kendall and the Sen’s Curvature tests are used to assess the statistical significance and the magnitude of the trends, respectively. The drainage area of the Belo Monte HPP is dominated by two climatic types: an equatorial climate in the north-central portion of the basin, with high temperatures and little variation throughout the year (22°C to 32°C), in addition to more frequent precipitation; and a tropical climate in the south-central sector, which experiences slightly more pronounced temperature variations throughout the year (20°C to 33°C) and presents a more defined wet and dry periods. The south-central portion of the basin exhibits the highest temperature extremes, with the highest TX and the lowest TN of the year occurring in this area, both due to the predominant days of clear skies in the austral winter, as to the advance of intense masses of polar air at this period. The diurnal temperature range is lower in the north-central sector when compared to that in the south-central region since the first has greater cloud cover and a higher frequency of precipitation. The largest annual rainfall volumes are concentrated at the north and west sides (more than 1,800 mm) and the precipitation extremes are heterogeneous across the basin. The maximum number of consecutive dry days increases from the north (10 to 20 days) to the south (90 to 100 days). The annual frequency of warm days and nights is increasing significantly in a large part of the basin with a magnitude ranging predominantly from +7 to +19 days/decade. The annual rainfall shows a predominant elevation sign of up to +200 mm/decade only in the northern part of the basin, while the remainder shows a reduction of up to -100 mm/decade. The duration of drought periods increases in the south-central sector of the basin, reaching up to +13 days/decade in some areas. The results of this study will be used in the future as an important input, together with exposure, sensibility, and local adaptation capacity, to design adaptation strategies that are more consistent with local reality and to the needs of local communities.</p>

scholarly journals Reflections on a field across time and space: the emergent medical and health humanities in South Africa

2018 ◽  
Vol 44 (4) ◽  
pp. 263-269 ◽  
Author(s):  
Victoria Jane Hume ◽  
Megan Wainwright
Keyword(s):  
South Africa ◽  
South African ◽  
Cross Cultural ◽  
The South ◽  
Health Humanities ◽  
Cultural Experience ◽  
The North ◽  
Qualitative Evidence ◽  
The Uk ◽  
Personal Reflections

In this paper, we draw on our own cross-cultural experience of engaging with different incarnations of the medical and health humanities (MHH) in the UK and South Africa to reflect on what is distinct and the same about MHH in these locations. MHH spaces, whether departments, programmes or networks, have espoused a common critique of biomedical dualism and reductionism, a celebration of qualitative evidence and the value of visual and performative arts for their research, therapeutic and transformative social potential. However, there have also been differences, and importantly a different ‘identity’ among some leading South African scholars and practitioners, who have felt that if MHH were to speak from the South as opposed to the North, they would say something quite different. We seek to contextualise our personal reflections on the development of the field in South Africa over recent years within wider debates about MHH in the context of South African academia and practice, drawing in part on interviews conducted by one of the authors with South African researchers and practitioners and our own reflections as ‘Northerners’ in the ‘South’.

Cold Induced Abnormal Catches of Sole

1998 ◽  
Vol 78 (1) ◽  
pp. 345-347 ◽  
Author(s):  
J.W. Horwood ◽  
R.S. Millner
Keyword(s):  
North Sea ◽  
Cold Water ◽  
The South ◽  
Total Allowable Catch ◽  
The North ◽  
Solea Solea ◽  
The North Sea ◽  
The Uk ◽  
The Eu ◽  
Made In

Large catches of sole (Solea solea) were made in early 1996 from the south-western North Sea. Sole suffer physiological damage in waters below 3–4 C. In February 1996 cold water of 3–4 C unusually extended from the Continental coast onto the Dogger Bank. It is likely that the increased catches were due to the consequential distribution and behaviour of the sole, making them more susceptible to capture.Exceptionally large catches of mature sole (Solea solea (L.)) were made in February 1996 by Lowestoft fishermen from the south-western North Sea. Surprisingly this was not welcome. The UK allocation of the North Sea sole is -4 % of the EU Total Allowable Catch (TAC), and fishermen are restricted nationally, and by the fishing companies, to a tightly managed ration. The Lowestoft Journal (8 March 1996) reported the suspension of a local fishing skipper for not throwing back 5000 kg of sole caught in the Silver Pits. We will show that the abnormal catches were due to exceptionally cold waters.Sole in the North Sea are at the northern extremity of their range, with sole seldom living in waters below 5°C (Horwood, 1993). In fact, North Sea sole were successfully introduced into Lake Quarun, Egypt, where they lived in temperatures in excess of 30°C (El-Zarka, 1965). Young sole migrate from their shallow inshore nursery grounds, such as the Waddensea, as winter approaches (Creutzberg & Fonds, 1971).

scholarly journals On the spatial segregation of helicity by inertial waves in dynamo simulations and planetary cores

2018 ◽  
Vol 851 ◽  
pp. 268-287 ◽  
Author(s):  
P. A. Davidson ◽  
A. Ranjan
Keyword(s):  
Numerical Simulations ◽  
Strongly Correlated ◽  
Inertial Waves ◽  
The South ◽  
The North ◽  
Planetary Cores ◽  
Local Wave ◽  
Wave Flux ◽  
The Relationship

The distribution of kinetic helicity in a dipolar planetary dynamo is central to the success of that dynamo. Motivated by the helicity distributions observed in numerical simulations of the Earth’s dynamo, we consider the relationship between the kinetic helicity, $h=\boldsymbol{u}\boldsymbol{\cdot }\unicode[STIX]{x1D735}\times \boldsymbol{u}$, and the buoyancy field that acts as a source of helicity, where $\boldsymbol{u}$ is velocity. We show that, in the absence of a magnetic field, helicity evolves in accordance with the equation $\unicode[STIX]{x2202}h/\unicode[STIX]{x2202}t=-\unicode[STIX]{x1D735}\boldsymbol{\cdot }\boldsymbol{F}+S_{h}$, where the flux, $\boldsymbol{F}$, represents the transport of helicity by inertial waves, and the helicity source, $S_{h}$, involves the product of the buoyancy and the velocity fields. In the numerical simulations it is observed that the helicity outside the tangent cylinder is predominantly negative in the north and positive in the south, a feature which the authors had previously attributed to the transport of helicity by waves (Davidson & Ranjan, Geophys. J. Intl, vol. 202, 2015, pp. 1646–1662). It is also observed that there is a strong spatial correlation between the distribution of $h$ and of $S_{h}$, with $S_{h}$ also predominantly negative in the north and positive in the south. This correlation tentatively suggests that it is the in situ generation of helicity by buoyancy that establishes the distribution of $h$ outside the tangent cylinder, rather than the dispersal of helicity by waves, as had been previously argued by the authors. However, although $h$ and $S_{h}$ are strongly correlated, there is no such correlation between $\unicode[STIX]{x2202}h/\unicode[STIX]{x2202}t$ and $S_{h}$, as might be expected if the distribution of $h$ were established by an in situ generation mechanism. We explain these various observations by showing that inertial waves interact with the buoyancy field in such a way as to induce a source $S_{h}$ which has the same sign as the helicity in the local wave flux, and that the sign of $h$ is simply determined by the direction of that flux. We conclude that the observed distributions of $h$ and $S_{h}$ outside the tangent cylinder are consistent with the transport of helicity by waves.

scholarly journals Bioclimatic Impact on the Carob Seeds Morphological Diversity in Morocco

2021 ◽  
Vol 18 (1) ◽  
pp. 207-217
Author(s):  
Foughali Boubkar ◽  
Fghire Rachid ◽  
Anaya Fatima ◽  
Issa Ali Oudou ◽  
Tahrouch Saadia ◽  
...  
Keyword(s):  
Morphological Diversity ◽  
Annual Rainfall ◽  
Shape Parameters ◽  
The South ◽  
Rainfall Gradient ◽  
Dry Land ◽  
The North ◽  
Carob Tree ◽  
Length Width ◽  
Ceratonia Siliqua L

The carob tree, Ceratonia siliqua L., a typical thermophilic sclerophyllous species, is a multipurpose tree (agronomic, silvicultural and pastoral) with aromatic and medicinal properties. Due to its geographical distribution, it occupies different countries of the Mediterranean. In Morocco, this species spreads over the different bioclimatic from the arid in the south to the humid in the north. The present work, study the morphological diversity of the seeds of five carob tree ecotypes distributed along a rainfall gradient (from the arid in the south to the humid one towards the north of the country). The shape parameters studied are the length, width, thickness, weight, volume and density of the seeds.The results obtained show that the carob tree ecotypes are characterized by significant differences in the different morphological parameters of the seeds among the five ecotypes studied. Indeed, dry land seeds are generally reduced in length, volume and weight, while those in humid regions are larger in weight and size. Those of the dry sowing areas have moderate parameters. The variance analysis shows that the origin of the ecotypes hada significant effect on the various shape parameters. Moreover, the multiple comparison of averages revealed different distinct groups. ACP analysis revealed that seed weight and volume is strongly correlated with the first component (the bioclimatic origin and the annual rainfall of the site of origin). While the second component corresponds to the parameters of length, width and thickness of the seeds. As for the factor 3, it corresponds to the density of the seeds which is not dependent on the other variables.In terms of conclusion, it is deduced that in Morocco, the carob tree seeds are characterized by a large morphological diversity which varies according to the rainfall gradient.

scholarly journals Less Frequent but More Severe Hydrological Drought Events Emerge at 1.5 and 2 °C Warming Levels over the Wudinghe Watershed in northern China

2018 ◽  
Author(s):  
Yang Jiao ◽  
Xing Yuan
Keyword(s):  
Land Surface ◽  
Climate Models ◽  
Coupled Model ◽  
Northern China ◽  
Hydrological Drought ◽  
Drought Severity ◽  
Drought Frequency ◽  
Drought Characteristics ◽  
The Impact ◽  
Hydrological Droughts

Abstract. Assessment of changes in hydrological droughts at specific warming levels (e.g., 1.5 or 2 °C) is important for an adaptive water resources management with consideration of the 2015 Paris Agreement. However, most studies focused on the response of drought frequency to the warming and neglected other drought characteristics including severity. By using a semiarid watershed in northern China (i.e., Wudinghe) as an example, here we show less frequent but more severe hydrological drought events emerge at both 1.5 and 2 °C warming levels. We used meteorological forcings from eight Coupled Model Intercomparison Project Phase 5 climate models with four representative concentration pathways, to drive a newly developed land surface hydrological model to simulate streamflow, and analyzed historical and future hydrological drought characteristics based on the Standardized Streamflow Index. The Wudinghe watershed will reach the 1.5 °C (2 °C) warming level around 2006–2025 (2019–2038), with an increase of precipitation by 6 % (9 %) and runoff by 17 % (27 %) as compared to the baseline period (1986–2005). This results in a drop of drought frequency by 26 % (27 %). However, the drought severity will rise dramatically by 63 % (30 %), which is mainly caused by the increased variability of precipitation and evapotranspiration. The climate models contribute to more than 82 % of total uncertainties in the future projection of hydrological droughts. This study suggests that different aspects of hydrological droughts should be carefully investigated when assessing the impact of 1.5 and 2 °C warming.

scholarly journals Drought Characteristics and Propagation in the Semiarid Heihe River Basin in Northwestern China

2019 ◽  
Vol 20 (1) ◽  
pp. 59-77 ◽  
Author(s):  
Feng Ma ◽  
Lifeng Luo ◽  
Aizhong Ye ◽  
Qingyun Duan
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Human Activities ◽  
Meteorological Drought ◽  
Hydrological Drought ◽  
Heihe River Basin ◽  
Heihe River ◽  
Propagation Time ◽  
Drought Characteristics ◽  
Hydrological Droughts

Abstract Meteorological and hydrological droughts can bring different socioeconomic impacts. In this study, we investigated meteorological and hydrological drought characteristics and propagation using the standardized precipitation index (SPI) and standardized streamflow index (SSI), over the upstream and midstream of the Heihe River basin (UHRB and MHRB, respectively). The correlation analysis and cross-wavelet transform were adopted to explore the relationship between meteorological and hydrological droughts in the basin. Three modeling experiments were performed to quantitatively understand how climate change and human activities influence hydrological drought and propagation. Results showed that meteorological drought characteristics presented little difference between UHRB and MHRB, while hydrological drought events are more frequent in the MHRB. In the UHRB, there were positive relationships between meteorological and hydrological droughts, whereas drought events became less frequent but longer when meteorological drought propagated into hydrological drought. Human activities have obviously changed the positive correlation to negative in the MHRB, especially during warm and irrigation seasons. The propagation time varied with seasonal climate characteristics and human activities, showing shorter values due to higher evapotranspiration, reservoir filling, and irrigation. Quantitative evaluation showed that climate change was inclined to increase streamflow and propagation time, contributing from −57% to 63%. However, more hydrological droughts and shorter propagation time were detected in the MHRB because human activities play a dominant role in water consumption with contribution rate greater than (−)89%. This study provides a basis for understanding the mechanism of hydrological drought and for the development of improved hydrological drought warning and forecasting system in the HRB.

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 Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian River: the individual roles of climate variability and land use change

2020 ◽  
Author(s):  
Artemis Roodari ◽  
Markus Hrachowitz ◽  
Farzad Hassanpour ◽  
Mostafa Yaghoobzadeh
Keyword(s):  
Water Balance ◽  
Climate Variability ◽  
River Basin ◽  
Irrigation Water ◽  
Hydrological Drought ◽  
Human Intervention ◽  
Study Region ◽  
Drought Characteristics ◽  
A Minor ◽  
Hydrological Droughts

Abstract. The transboundary Helmand River basin is the main drainage system for large parts of Afghanistan and the Sistan region of Iran. Due to the reliance of this arid region on water from the Helmand River, a better understanding of hydrological drought pattern and the underlying drivers in the region are critically required for an effective management of the available water. The objective of this paper is therefore to analyse and quantify spatio-temporal pattern of drought and the underlying processes in the study region. More specifically we test for the Helmand River Basin the following hypotheses for the 1970–2006 period: (1) drought characteristics, including frequency and severity systematically changed over the study period, (2) the spatial pattern and processes of drought propagation through the Helmand River Basin also changed and (3) the relative roles of climate variability and human influence on changes in hydrological droughts can be quantified. It was found that drought characteristics varied throughout the study period, but did largely show no systematic trends. The same was observed for the time series of drought indices SPI and SPEI, which exhibited considerable spatial coherence and synchronicity throughout the basin indicating that, overall, droughts similarly affect the entire HRB with little regional or local differences. In contrast, analysis of SDI exhibited significant negative trends in the lower parts of the basin, indicating an intensification of hydrological droughts. It could be shown that with a mean annual precipitation of ~250 mm y-1, streamflow deficits and thus hydrological drought throughout the HRB are largely controlled by precipitation deficits, whose annual anomalies on average account for ±50 mm y-1 or ~20 % of the water balance of the HRB, while anomalies of total evaporative fluxes on average only account for ±20 mm y-1. The two reservoirs in the HRB only played a minor role for the downstream propagation of streamflow deficits, as indicated by the mean difference between inflow and outflow during drought periods which did not exceed ~0.5 % of the water balance of the HRB. Irrigation water abstraction had a similarly limited effect on the magnitude of streamflow deficits, accounting for ~10 % of the water balance of the HRB. However, the downstream parts of the HRB moderated the further propagation of streamflow deficits and associated droughts in the early decades of the study period. This drought moderation function of the lower basin was gradually and systematically inverted by the end of the study period, when the lower basin eventually amplified the downstream propagation of flow deficits and droughts. This shift from drought moderation to drought amplification in the lower basin is likely a consequence of increased agricultural activity and the associated increases in irrigation water demand from ~13 mm y-1 at the beginning of the study period to ~23 mm y-1 at the end and thus in spite of being only a minor fraction of the water balance. Overall the results of this study illustrate that flow deficits and the associated droughts in the HRB clearly reflect the dynamic interplay between temporally varying regional differences in hydro-meteorological variables together with subtle and temporally varying effects linked to direct human intervention.

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