An Evaluation of Probability of Occurrence of Hydrological Extremes

2021 ◽  
pp. 69-78
Author(s):  
M.B. Joisy ◽  
Deepa G.S. Varghese
Keyword(s):  
Severe Drought ◽  
Catchment Scale ◽  
Probability Of Occurrence ◽  
Hydrological Extremes ◽  
Storage Reservoirs ◽  
Scarce Water ◽  
Droughts And Floods ◽  
Modelling Techniques ◽  
Streamflow Data ◽  
Floods And Droughts

The hydrological extremes viz. droughts and floods, are global recurring natural hazards which are dynamic with respect to space and time impacting many people. The increase in the number of instances of these hydrological events in the past has steered the research in the direction towards evaluation of probability of occurrence of droughts and floods on a catchment scale, for proper planning and decision making in ideal allocation of the scarce water resources and mitigation of flood. Understanding and evaluating hydrological extremes becomes important in terms of sizing of storage reservoirs for combating droughts and floods, while its prediction becomes the key in reduction of its consequences. This study presents a summarized evaluation of probability of occurrence of floods and droughts in Bhavani basin of Kerala, using Herbst method, for a period of 40 years from 2002 to 2042, using streamflow data. As per the analysis, the most severe drought is expected to hit the basin in the year 2022- 2023 while the worst flood is expected in the year 2040 -2041. The novelty of the study is in applying the Herbst method for evaluating the probability of occurrence of floods in a catchment area without adopting rigorous hydrological modelling techniques.

Modelling hydrological droughts and floods in the Volta Basin, West Africa 

2021 ◽  
Author(s):  
Solomon Hailu Gebrechorkos ◽  
Ming Pan ◽  
Peirong Lin ◽  
David Pritchard ◽  
Nathan Forsythe ◽  
...  
Keyword(s):  
High Resolution ◽  
Extreme Events ◽  
Future Climate Change ◽  
Multiple Time Scales ◽  
Hydrological Extremes ◽  
Wide Range ◽  
Increasing Trend ◽  
Droughts And Floods ◽  
Streamflow Data ◽  
The Impact

<p>Hydrological extreme events such as droughts and floods have a wide range of impacts on society and sectors such as agriculture and energy production. The impact of these extremes are projected to increase with future climate change and there is an urgent need to develop adaptation measures to reduce and manage the impacts. Long-term analysis of hydrological extremes, using a combination of models and climate data, helps better plan and manage water resources under global change. In this study, we modelled and analyzed hydrological extremes of the Volta river basin at very high-resolution (>10000 river reaches) using the Variable Infiltration Capacity (VIC) hydrological model, the vector-based river network routing model (RAPID), and high-resolution meteorological forcing datasets. The output from the VIC model is evaluated at multiple time scales (daily to annual) and for extreme events (droughts and floods) using observed streamflow data during the period 1979-2013.  The model performed very well in areas less affected by dams, with performance increasing from daily to annual time scale. The modelled streamflow data is used to assess changes and variability in droughts (duration days and severity) and floods (annual daily maximum). The results show a decreasing and increasing trend in moderate and severe droughts in northern-eastern and southern parts of the basin, respectively. An increasing trend in floods is observed in the upper part of the basin (Black and White Volta) and the main river of the Lower Volta and we found a strong correlation with changes in precipitation and soil moisture.</p>

Cross-scale evaluation of catchment- and global-scale hydrological model simulations of drought characteristics across eight large river catchments

2021 ◽  
Author(s):  
Amit Kumar ◽  
Simon N Gosling ◽  
Matthew F Johnson ◽  
Jamal Zaherpour ◽  
Guoyong Leng ◽  
...  
Keyword(s):  
Time Series ◽  
Large River ◽  
Global Scale ◽  
Historical Period ◽  
Severe Drought ◽  
Hydrological Models ◽  
Catchment Scale ◽  
Hydrological Extremes ◽  
Intercomparison Project ◽  
Monthly Runoff

Abstract Although global- and catchment-scale hydrological models are often shown to accurately simulate long-term runoff time-series, far less is known about their suitability for capturing hydrological extremes, such as droughts. Here we evaluated runoff simulations from nine catchment scale hydrological models (CHMs) and eight global scale hydrological models (GHMs) for eight large catchments: Upper Amazon, Lena, Upper Mississippi, Upper Niger, Rhine, Tagus, Upper Yangtze and Upper Yellow. The simulations were conducted within the framework of phase 2a of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2a). We evaluated the ability of the CHMs, GHMs and their respective ensemble means (Ens-CHM and Ens-GHM) to simulate observed monthly runoff and hydrological droughts over 31 years (1971–2001). Observed and simulated hydrological drought events were identified using the Standardised Runoff Index (SRI) and were classified based on intensity. Our results show that for all eight catchments, CHMs out-performed GHMs in monthly runoff estimation showing a better representation of observed runoff than GHMs. The number of drought events identified under different drought categories (i.e. SRI values of -1 to -1.49, -1.5 to -1.99, and ≤-2) varied significantly between models. All the models, as well as the two ensemble means present limited ability to accurately simulate severe drought events in all eight catchments, in terms of their timing and intensity. By analysing the monthly runoff time-series for several extreme droughts over the historical period, we identify room for improvement in the models so that extreme droughts may ultimately be better represented by both CHMs and GHMs.

Influence of Discharges from Storage Reservoirs on the Tastes and Odours Appearing in the Seine and Marne Rivers

1982 ◽  
Vol 14 (4-5) ◽  
pp. 43-58 ◽  
Author(s):  
M Rizet ◽  
J Mouchet
Keyword(s):  
Water Quality ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Severe Drought ◽  
Storage Reservoirs ◽  
Metabolite Concentrations

This study was conducted in order to understand the taste and odour problems that occurred in the Seine and the Marne rivers during the severe drought of 1976. Samples were taken every 15 days from several locations in the rivers themselves and from storage reservoirs upstream from Paris. Algae and actinomycetes were identified and counted. Metabolite concentrations were measured. These data were correlated with threshold odor numbers and bacteriological water quality parameters.

scholarly journals Assessment of surface water resources availability using catchment modeling and the results of tracer studies in the meso-scale Migina Catchment, Rwanda

2013 ◽  
Vol 10 (12) ◽  
pp. 15375-15408 ◽  
Author(s):  
O. Munyaneza ◽  
A. Mukubwa ◽  
S. Maskey ◽  
J. Wenninger ◽  
S. Uhlenbrook
Keyword(s):  
Decision Making ◽  
Water Resources ◽  
Hydrological Model ◽  
Base Flow ◽  
Hydrological Processes ◽  
Model Parameters ◽  
Water Resources Planning ◽  
Catchment Scale ◽  
Streamflow Data ◽  
Resources Planning

Abstract. In the last couple of years, different hydrological research projects were undertaken in the Migina catchment (243.2 km2), a tributary of the Kagera river in Southern Rwanda. These projects were aimed to understand hydrological processes of the catchment using analytical and experimental approaches and to build a pilot case whose experience can be extended to other catchments in Rwanda. In the present study, we developed a hydrological model of the catchment, which can be used to inform water resources planning and decision making. The semi-distributed hydrological model HEC-HMS (version 3.5) was used with its soil moisture accounting, unit hydrograph, liner reservoir (for base flow) and Muskingum-Cunge (river routing) methods. We used rainfall data from 12 stations and streamflow data from 5 stations, which were collected as part of this study over a period of two years (May 2009 and June 2011). The catchment was divided into five sub-catchments each represented by one of the five observed streamflow gauges. The model parameters were calibrated separately for each sub-catchment using the observed streamflow data. Calibration results obtained were found acceptable at four stations with a Nash–Sutcliffe Model Efficiency of 0.65 on daily runoff at the catchment outlet. Due to the lack of sufficient and reliable data for longer periods, a model validation (split sample test) was not undertaken. However, we used results from tracer based hydrograph separation from a previous study to compare our model results in terms of the runoff components. It was shown that the model performed well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and base flow. We observed considerable disparities in the parameters (e.g. groundwater storage) and runoff components across the five sub-catchments, that provided insights into the different hydrological processes at sub-catchment scale. We conclude that such disparities justify the need to consider catchment subdivisions, if such parameters and components of the water cycle are to form the base for decision making in water resources planning in the Migina catchment.

scholarly journals Impacts of wildfire and post-fire land management on hydrological and sediment processes in a humid Mediterranean headwater catchment

2021 ◽  
Author(s):  
Joao Pedro Nunes ◽  
Léonard Bernard-Jannin ◽  
María Luz Rodríguez-Blanco ◽  
Anne-Karine Boulet ◽  
Juliana Marisa Santos ◽  
...  
Keyword(s):  
Sediment Yield ◽  
Agricultural Landscape ◽  
Sediment Concentration ◽  
Dominant Factor ◽  
Severe Drought ◽  
Negative Consequences ◽  
Catchment Scale ◽  
Burnt Area ◽  
Rainfall Events ◽  
The North

<p>The extensive afforestation of the Mediterranean rim of Europe in recent decades has increased the number of wildfire disturbances on hydrological and sediment processes, but the impacts on headwater catchments is still poorly understood, especially when compared with the previous agricultural landscape. This work monitored an agroforestry catchment in the north-western Iberian Peninsula, with plantation forests mixed with traditional agriculture using soil conservation practices, for one year before the fire and for three years afterwards, during which period the burnt area was plowed and reforested. During this period, continuous data was collected for meteorology, streamflow and sediment concentration at the outlet, erosion features were mapped and measured after major rainfall events, and channel sediment dynamics were monitored downstream from the agricultural and the burnt forest area. Data from 202 rainfall events with over 10 mm was analysed in detail.</p><p>Results show that the fire led to a notable impact on sediment processes during the first two post-fire years, but not on streamflow processes; this despite the small size of the burnt area (10% of the catchment) and the occurrence of a severe drought in the first year after the fire. During this period, soil loss at the burnt forest slopes was much larger than that at most traditionally managed fields, and, ultimately, led to sediment exhaustion. At the catchment scale, storm characteristics were the dominant factor behind streamflow and sediment yield both before and after the fire. However, the data indicated a shift from detachment-limited sediment yield before the fire, to transport-limited sediment yield afterwards, with important increases in streamflow sediment concentration. This indicates that even small fires can temporarily change sediment processes in agroforestry catchments, with potential negative consequences for downstream water quality.</p>

scholarly journals ASSESSING DROUGHT CHARACTERISTICS OF MELAKA BASIN USING JOINT METEOROLOGICAL AND STREAMFLOW INDICES

2020 ◽  
Vol 80 (1) ◽  
Author(s):  
Kee An Hong ◽  
Jer Lang Hong ◽  
Izihan Ibrahim
Keyword(s):  
Drought Index ◽  
Meteorological Drought ◽  
Hydrological Drought ◽  
Drought Indices ◽  
Severe Drought ◽  
Frequency Of Occurrence ◽  
Streamflow Data ◽  
Hydrological Droughts ◽  
Drought Occurrence ◽  
Meteorological Droughts

In this study, drought occurrence in the Melaka basin has been assessed using the meteorological and hydrological drought indices. A continuous rainfall and streamflow data of 40 years were used for drought analysis. Results show that in terms of meteorological drought index, the severe drought occurred in 1986-1988. The streamflow drought index indicates that the extreme drought occurred in 1982-1984. Further analysis based on seasonal precipitation and streamflow data shows that there is no drought for 79% of the time for the period 1960-2000 where there are hydrological records. For most of the dry and wet seasons, it is more likely that the frequency of occurrence of hydrological droughts only is higher than the frequency of occurrence of meteorological and hydrological droughts simultaneously or only meteorological droughts.

scholarly journals Inferring Soil Moisture Memory from Streamflow Observations Using a Simple Water Balance Model

2013 ◽  
Vol 14 (6) ◽  
pp. 1773-1790 ◽  
Author(s):  
Rene Orth ◽  
Randal D. Koster ◽  
Sonia I. Seneviratne
Keyword(s):  
Soil Moisture ◽  
Water Balance ◽  
Weather Forecasting ◽  
Water Balance Model ◽  
Balance Model ◽  
Catchment Scale ◽  
Spatially Distributed ◽  
Optimized Model ◽  
Streamflow Data

Abstract Soil moisture is known for its integrative behavior and resulting memory characteristics. Soil moisture anomalies can persist for weeks or even months into the future, making initial soil moisture a potentially important contributor to skill in weather forecasting. A major difficulty when investigating soil moisture and its memory using observations is the sparse availability of long-term measurements and their limited spatial representativeness. In contrast, there is an abundance of long-term streamflow measurements for catchments of various sizes across the world. The authors investigate in this study whether such streamflow measurements can be used to infer and characterize soil moisture memory in respective catchments. Their approach uses a simple water balance model in which evapotranspiration and runoff ratios are expressed as simple functions of soil moisture; optimized functions for the model are determined using streamflow observations, and the optimized model in turn provides information on soil moisture memory on the catchment scale. The validity of the approach is demonstrated with data from three heavily monitored catchments. The approach is then applied to streamflow data in several small catchments across Switzerland to obtain a spatially distributed description of soil moisture memory and to show how memory varies, for example, with altitude and topography.

Genetic algorithm-based optimization of water resources allocation under drought conditions

2010 ◽  
Vol 10 (4) ◽  
pp. 517-525 ◽  
Author(s):  
Z. Rao ◽  
D. Debski ◽  
D. Webb ◽  
R. Harpin
Keyword(s):  
Genetic Algorithms ◽  
Water Resources ◽  
Optimization Technique ◽  
Severe Drought ◽  
Water Resource System ◽  
Drought Conditions ◽  
Scarce Water ◽  
Operating Strategies ◽  
Multiple Reservoir ◽  
City Of London

The efficient allocation of increasingly scarce water resources is a growing challenge worldwide, particularly during times of drought. This paper describes the development and application of an innovative technique to optimize the allocation of raw water supply to the city of London, UK during a period of drought in 2006. Using genetic algorithms, an optimization tool was developed to derive near-optimal operating strategies for the water company's multiple reservoir system for different projected rainfall scenarios and also to test the robustness of drought contingency strategies for operating the reservoirs down to a lower level under a severe drought condition. The project demonstrated that this approach is rigorous yet practical, the optimization technique is robust and effective and that optimal water allocation is an efficient measure to overcome water scarcity under drought conditions and mitigate consequent impacts. The potential application of genetic algorithms to the day to day operation of a complex water resource system represents a step-change in the industry's approach to managing such systems.

scholarly journals Modeling the Underlying Drivers of Natural Vegetation Occurrence in West Africa with Binary Logistic Regression Method

2021 ◽  
Vol 13 (9) ◽  
pp. 4673
Author(s):  
Beatrice Asenso Barnieh ◽  
Li Jia ◽  
Massimo Menenti ◽  
Min Jiang ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Logistic Regression ◽  
West Africa ◽  
Human Activities ◽  
Net Primary Productivity ◽  
Binary Logistic Regression ◽  
Natural Vegetation ◽  
Severe Drought ◽  
Economic Activities ◽  
Probability Of Occurrence ◽  
Year 2000

The occurrence of natural vegetation at a given time is determined by interplay of multiple drivers. The effects of several drivers, e.g., geomorphology, topography, climate variability, accessibility, demographic indicators, and changes in human activities on the occurrence of natural vegetation in the severe drought periods and, prior to the year 2000, have been analyzed in West Africa. A binary logistic regression (BLR) model was developed to better understand whether the variability in these drivers over the past years was statistically significant in explaining the occurrence of natural vegetation in the year 2000. Our results showed that multiple drivers explained the occurrence of natural vegetation in West Africa at p < 0.05. The dominant drivers, however, were site-specific. Overall, human influence indicators were the dominant drivers in explaining the occurrence of natural vegetation in the selected hotspots. Human appropriation of net primary productivity (HANPP), which is an indicator of human socio-economic activities, explained the decreased likelihood of natural vegetation occurrence at all the study sites. However, the impacts of the remaining significant drivers on natural vegetation were either positive (increased the probability of occurrence) or negative (decreased the probability of occurrence), depending on the unique environmental and socio-economic conditions of the areas under consideration. The study highlights the significant role human activities play in altering the normal functioning of the ecosystem by means of a statistical model. The research contributes to a better understanding of the relationships and the interactions between multiple drivers and the response of natural vegetation in West Africa. The results are likely to be useful for planning climate change adaptation and sustainable development programs in West Africa.

scholarly journals Protection Mehcanism Against Drought In Axsonopus Compressus: Insight of Physio-Biochemical Traits, Antioxident Interplay and Gene Experssion

2020 ◽  
Author(s):  
Mohsin Nawaz ◽  
Li Liao ◽  
Farrukh Azeem ◽  
Umair Ashraf ◽  
Ali Zohaib ◽  
...  
Keyword(s):  
Drought Stress ◽  
Soluble Sugar ◽  
Field Capacity ◽  
Physiological Data ◽  
Severe Drought ◽  
Severe Damage ◽  
Environmental Constraint ◽  
Stunted Growth ◽  
Defense Systems ◽  
Scarce Water

Abstract Drought is a major environmental constraint that affects plant growth and internal physio-biochemical features. The present study was conducted to evaluate the performance of three different Axonopus compressus accessions, i.e., A-38, A-58, and A-59 under well-watered (WW), low drought (LD), moderate (MD) and severe drought (SD) conditions at field capacity of 100, 80, 60, and 40%, respectively. Results indicated that drought-induced higher production of proline and soluble sugar (SS) up to 40 and 41% respectively, than control. Drought stress caused excessive production of H 2 O 2 while the highest value (10.15µmol g -1 FW) was observed in the A-38 under SD. However, the lowest enzymatic (SOD, POD, CAT, and APX) activity were observed in A-38 than A-58 and A-59 respectively, in the SD. In A-58 the efficient enzymatic and nonenzymatic defense systems hinder the severe damage while stunted growth occurred in Axonopus compressus accessions at SD which were more pronounced in the A-38. Overall, the performance of all Axonopus compressus accessions under drought stress was recorded as A-58>A-59>A-38. The qRT PCR expression analysis also revealed highest expression of drought responsive genes in A-58 and reinforced the findings of physiological data. These results suggested the plant's ability to maintain its functions during drought induction could be used for further investigation under scarce water for developing drought tolerance.

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