scholarly journals The critical role of uncertainty in projections of hydrological Extremes

2016 ◽  
Author(s):  
Hadush K. Meresa ◽  
Renata J. Romanowicz
Keyword(s):  
Hydrological Model ◽  
Climate Model ◽  
Critical Role ◽  
Resource Planning ◽  
Low Flow ◽  
Model Parameters ◽  
Climate Projections ◽  
Hydrological Extremes ◽  
Hbv Model ◽  
Distribution Fit

Abstract. This paper aims to quantify the uncertainty in the projections of future hydrological extremes in the BialaTarnowska River basin, south Poland. We follow a multi-model approach based on several climate projections obtained from the EUROCORDEX initiative, raw and downscaled realizations of catchment precipitation and temperature, and flow simulations derived using the hydrological HBV model. The projections cover the 21st century. Three sources of uncertainty were considered: one related to the hydrological model parameters uncertainty, the second related to climate projection ensemble spread and the third related to the distribution fit. The uncertainty of projected extreme indices related to hydrological model parameters was conditioned on flow observations from the reference period using the Generalised Likelihood Uncertainty Estimation approach, with separate weighting for high and low flow extremes. Flood quantiles were estimated using Generalize Extreme Value (GEV) distribution at different return periods and were based on two different lengths of the flow time series. The sensitivity analysis based on ANOVA shows that the uncertainty introduced by the HBV model parameters can be larger than the climate model variability and distribution fit uncertainty for the low-flow extremes whilst for the high-flow extremes higher uncertainty is observed from climate models than from hydrological parameter and distribution fit uncertainties. This implies that ignoring one of the three uncertainty sources may cause great risk to future hydrological extreme adaptations and water resource planning and management.

scholarly journals The critical role of uncertainty in projections of hydrological extremes

2017 ◽  
Vol 21 (8) ◽  
pp. 4245-4258 ◽  
Author(s):  
Hadush K. Meresa ◽  
Renata J. Romanowicz
Keyword(s):  
Hydrological Model ◽  
Climate Model ◽  
Critical Role ◽  
Resource Planning ◽  
High Flow ◽  
Low Flow ◽  
Model Parameters ◽  
Climate Projections ◽  
Hydrological Extremes ◽  
Distribution Fit

Abstract. This paper aims to quantify the uncertainty in projections of future hydrological extremes in the Biala Tarnowska River at Koszyce gauging station, south Poland. The approach followed is based on several climate projections obtained from the EURO-CORDEX initiative, raw and bias-corrected realizations of catchment precipitation, and flow simulations derived using multiple hydrological model parameter sets. The projections cover the 21st century. Three sources of uncertainty are considered: one related to climate projection ensemble spread, the second related to the uncertainty in hydrological model parameters and the third related to the error in fitting theoretical distribution models to annual extreme flow series. The uncertainty of projected extreme indices related to hydrological model parameters was conditioned on flow observations from the reference period using the generalized likelihood uncertainty estimation (GLUE) approach, with separate criteria for high- and low-flow extremes. Extreme (low and high) flow quantiles were estimated using the generalized extreme value (GEV) distribution at different return periods and were based on two different lengths of the flow time series. A sensitivity analysis based on the analysis of variance (ANOVA) shows that the uncertainty introduced by the hydrological model parameters can be larger than the climate model variability and the distribution fit uncertainty for the low-flow extremes whilst for the high-flow extremes higher uncertainty is observed from climate models than from hydrological parameter and distribution fit uncertainties. This implies that ignoring one of the three uncertainty sources may cause great risk to future hydrological extreme adaptations and water resource planning and management.

scholarly journals Sensitivity-guided evaluation of the HBV hydrological model parameterization

2012 ◽  
Vol 15 (3) ◽  
pp. 967-990 ◽  
Author(s):  
M. B. Zelelew ◽  
K. Alfredsen
Keyword(s):  
Sensitivity Analysis ◽  
Hydrological Model ◽  
River Basin Management ◽  
Low Flow ◽  
Model Parameters ◽  
Sensitivity Index ◽  
Analysis Method ◽  
Flow Conditions ◽  
Model Parameterization ◽  
Sensitivity Analysis Method

Applying hydrological models for river basin management depends on the availability of the relevant data information to constrain the model residuals. The estimation of reliable parameter values for parameterized models is not guaranteed. Identification of influential model parameters controlling the model response variations either by main or interaction effects is therefore critical for minimizing model parametric dimensions and limiting prediction uncertainty. In this study, the Sobol variance-based sensitivity analysis method was applied to quantify the importance of the HBV conceptual hydrological model parameterization. The analysis was also supplemented by the generalized sensitivity analysis method to assess relative model parameter sensitivities in cases of negative Sobol sensitivity index computations. The study was applied to simulate runoff responses at twelve catchments varying in size. The result showed that varying up to a minimum of four to six influential model parameters for high flow conditions, and up to a minimum of six influential model parameters for low flow conditions can sufficiently capture the catchments' responses characteristics. To the contrary, varying more than nine out of 15 model parameters will not make substantial model performance changes on any of the case studies.

scholarly journals Mekong River flow and hydrological extremes under climate change

2016 ◽  
Vol 20 (7) ◽  
pp. 3027-3041 ◽  
Author(s):  
Long Phi Hoang ◽  
Hannu Lauri ◽  
Matti Kummu ◽  
Jorma Koponen ◽  
Michelle T. H. van Vliet ◽  
...  
Keyword(s):  
Climate Change ◽  
River Flow ◽  
High Flow ◽  
Mekong River ◽  
Low Flow ◽  
Future Climate Change ◽  
Climate Projections ◽  
Low Flows ◽  
Hydrological Extremes ◽  
Hydrological Impact

Abstract. Climate change poses critical threats to water-related safety and sustainability in the Mekong River basin. Hydrological impact signals from earlier Coupled Model Intercomparison Project phase 3 (CMIP3)-based assessments, however, are highly uncertain and largely ignore hydrological extremes. This paper provides one of the first hydrological impact assessments using the CMIP5 climate projections. Furthermore, we model and analyse changes in river flow regimes and hydrological extremes (i.e. high-flow and low-flow conditions). In general, the Mekong's hydrological cycle intensifies under future climate change. The scenario's ensemble mean shows increases in both seasonal and annual river discharges (annual change between +5 and +16 %, depending on location). Despite the overall increasing trend, the individual scenarios show differences in the magnitude of discharge changes and, to a lesser extent, contrasting directional changes. The scenario's ensemble, however, shows reduced uncertainties in climate projection and hydrological impacts compared to earlier CMIP3-based assessments. We further found that extremely high-flow events increase in both magnitude and frequency. Extremely low flows, on the other hand, are projected to occur less often under climate change. Higher low flows can help reducing dry season water shortage and controlling salinization in the downstream Mekong Delta. However, higher and more frequent peak discharges will exacerbate flood risks in the basin. Climate-change-induced hydrological changes will have important implications for safety, economic development, and ecosystem dynamics and thus require special attention in climate change adaptation and water management.

scholarly journals Estimating the Effect of Climate Internal Variability and Source of Uncertainty in Climate-Hydrological Projections in a Representative Watershed of Northeastern China

2021 ◽  
Author(s):  
Wenjun Cai ◽  
Xueping Zhu ◽  
Xuehua Zhao ◽  
Yongbo Zhang
Keyword(s):  
Rainy Season ◽  
Hydrological Model ◽  
Swat Model ◽  
Internal Variability ◽  
Climate Simulation ◽  
Model Parameters ◽  
Climate Projections ◽  
Hydrological Simulation ◽  
Simulation Process ◽  
Uncertainty Sources

Abstract The decomposition and quantification of uncertainty sources in ensembles of climate-hydrological simulation chains is a key issue in climate impact researches. The mainly objectives of this study partitioning climate internal variability (CIV) and uncertainty sources in the climate-hydrological projections simulation process, the climate simulation process formed by six downscaled GCMs under two emission scenarios called GCMs-ES simulation chain, the hydrological simulation process add one calibrate Soil and Water Assessment Tool (SWAT) model called GCMs-ES-HM simulation chain. The CIV and external forcing of climate projections are investigated in each GCMs-ES simulation chain. The CIV of precipitation and ET are large in rainy season, and the single-to-noise ratio (SNR) are also relatively high in rainy season. Furthermore, the uncertainty decomposed frameworks based on analysis of variance (ANOVA) are established. The CIV and GCMs are the dominate contributors of runoff in rainy season. It worth noting the CIV can propagate from precipitation and ET to runoff projections. In additional, the hydrological model parameters are the third uncertainty contributor of runoff, which embody the hydrological model simulate process play important role in hydrological projections in future. The findings of this study advised that the uncertainty is complex in hydrological, hence, it is meaning and necessary to estimate the uncertainty in climate simulation process, the uncertainty analysis results can provide effectively efforts to reduce uncertainty and then give some positive suggestions to stakeholders for adaption countermeasure under climate change.

scholarly journals Hydrological model optimization using multi-gauge calibration (MGC) in a mountainous region

2020 ◽  
Author(s):  
Sead Ahmed Swalih ◽  
Ercan Kahya
Keyword(s):  
Climate Change ◽  
Model Calibration ◽  
Hydrological Model ◽  
Model Performance ◽  
Spatial Dimension ◽  
Model Parameters ◽  
Climate Projections ◽  
Predictive Capacity ◽  
Black Sea Region ◽  
The Impact

Abstract It is a challenge for hydrological models to capture complex processes in a basin with limited data when estimating model parameters. This study aims to contribute in this field by assessing the impact of incorporating spatial dimension on the improvement of model calibration. Hence, the main objective of this study was to evaluate the impact of multi-gauge calibration in hydrological model calibration for Ikizdere basin, Black Sea Region in Turkey. In addition, we have incorporated the climate change impact assessment for the study area. Four scenarios were tested for performance assessment of calibration: (1) using downstream flow data (DC), (2) using upstream data (UC), (3) using upstream and downstream data (Multi-Gauge Calibration – MGC), and (4) using upstream and then downstream data (UCDC). The results have shown that using individual gauges for calibration (1 and 2) improve the local predictive capacity of the model. MGC calibration significantly improved the model performance for the whole basin unlike 1 and 2. However, the local gauge calibrations statistical performance, compared to MGC outputs, was better for local areas. The UCDC yields the best model performance and much improved predictive capacity. Regarding the climate change, we did not observe an agreement amongst the future climate projections for the basin towards the end of the century.

scholarly journals Water Supply for Tongatapu; Past, Present and Future.

2021 ◽  
Author(s):  
◽  
Lopeti Tufui
Keyword(s):  
Water Balance ◽  
Water Supply ◽  
Climate Models ◽  
Climate Model ◽  
Meteorological Data ◽  
Critical Role ◽  
South Pacific Convergence Zone ◽  
Climate Projections ◽  
Enso Cycle ◽  
Freshwater Resource

<p>This thesis presents an investigation of the sustainability of the freshwater aquifer (groundwater) at Tongatapu, the main island of Tonga. Water balance modelling is applied to meteorological data to estimate freshwater recharge at a daily resolution for the period 1980-2018. These results demonstrate a very close coupling between recharge and precipitation but also the critical role played by the ENSO cycle in modulating the supply of freshwater on Tongatapu. They also show that previous water balance modelling for the island, conducted at a monthly resolution, has tended to underestimate the rate of recharge by ~8%.   Historical groundwater extraction rates for Tongatapu are also calculated by compiling monitoring data from operational pumping stations across the island. This shows that extraction rates have increased progressively over the past 50 years and approximately doubled in the last 10 years, as a consequence of increased demand from agriculture, tourism and population growth. Although the freshwater resource appears to be sustainable overall at current rates of supply and demand, there have been sustained periods of zero recharge, notably during strong El Nino events in winter (the dry season).   Climate model projections of future rainfall show that Tonga is situated in a region of great uncertainty, due to shortcomings in our knowledge of how the inability of the models to capture the ENSO cycle will respond to anthropogenic warming, and but moreover, climate models are currently unable to simulate the precise correct positioning of the South Pacific Convergence Zone which strongly influences the amount and seasonal distribution of regional rainfall. Nevertheless, this study also conducted predictive water balance modelling for Tongatapu for the end of the 21st century using the current CMIP5 climate projections for the region under a medium (scenarios RCP4.5) and high (RCP8.5) emissions scenario, in both cases showing substantial reductions in freshwater recharge rates compared to the present. These results raise serious concerns for the future sustainability of Tonga’s freshwater resource, especially if extraction rates continue to increase and salination of the aquifer increases as is highly likely due to sea level rise.   Although Tonga can do little to influence the global climate change mitigation effort, this research highlights the importance of addressing currently resolvable infrastructural problems in water supply and reticulation.</p>

scholarly journals Minimal CMIP Emulator (MCE v1.2): A new simplified method for probabilistic climate projections

2021 ◽  
Author(s):  
Junichi Tsutsui
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Forced Response ◽  
System Response ◽  
Model Parameters ◽  
Climate Projections ◽  
Impulse Response Functions ◽  
Model Intercomparison ◽  
Probabilistic Climate Projections

Abstract. Climate model emulators have a crucial role in assessing warming levels of many emission scenarios from probabilistic climate projections, based on new insights into Earth system response to CO2 and other forcing factors. This article describes one such tool, MCE, from model formulation to application examples associated with a recent model intercomparison study. The MCE is based on impulse response functions and parameterized physics of effective radiative forcing and carbon uptake over ocean and land. Perturbed model parameters for probabilistic projections are generated from statistical models and constrained with a Metropolis-Hastings independence sampler. A part of the model parameters associated with CO2-induced warming have a covariance structure, as diagnosed from complex climate models of the Coupled Model Intercomparison Project (CMIP). Although perturbed ensembles can cover the diversity of CMIP models effectively, they need to be constrained toward substantially lower climate sensitivity for the resulting historical warming to agree with the observed trends over recent decades. The model's simplicity and resulting successful calibration imply that a method with less complicated structures and fewer control parameters offers advantages when building reasonable perturbed ensembles in a transparent way. Experimental results for future scenarios show distinct differences between CMIP- and observation-consistent ensembles, suggesting that perturbed ensembles for scenario assessment need to be properly constrained with new insights into forced response over historical periods.

scholarly journals Climate change impacts on the seasonality and generation processes of floods – projections and uncertainties for catchments with mixed snowmelt/rainfall regimes

2015 ◽  
Vol 19 (2) ◽  
pp. 913-931 ◽  
Author(s):  
K. Vormoor ◽  
D. Lawrence ◽  
M. Heistermann ◽  
A. Bronstert
Keyword(s):  
Climate Change ◽  
Production Management ◽  
Climate Models ◽  
Hydrological Model ◽  
Climate Model ◽  
Climate Projections ◽  
High Mountain ◽  
Relative Role ◽  
Projected Changes ◽  
Rainfall Regimes

Abstract. Climate change is likely to impact the seasonality and generation processes of floods in the Nordic countries, which has direct implications for flood risk assessment, design flood estimation, and hydropower production management. Using a multi-model/multi-parameter approach to simulate daily discharge for a reference (1961–1990) and a future (2071–2099) period, we analysed the projected changes in flood seasonality and generation processes in six catchments with mixed snowmelt/rainfall regimes under the current climate in Norway. The multi-model/multi-parameter ensemble consists of (i) eight combinations of global and regional climate models, (ii) two methods for adjusting the climate model output to the catchment scale, and (iii) one conceptual hydrological model with 25 calibrated parameter sets. Results indicate that autumn/winter events become more frequent in all catchments considered, which leads to an intensification of the current autumn/winter flood regime for the coastal catchments, a reduction of the dominance of spring/summer flood regimes in a high-mountain catchment, and a possible systematic shift in the current flood regimes from spring/summer to autumn/winter in the two catchments located in northern and south-eastern Norway. The changes in flood regimes result from increasing event magnitudes or frequencies, or a combination of both during autumn and winter. Changes towards more dominant autumn/winter events correspond to an increasing relevance of rainfall as a flood generating process (FGP) which is most pronounced in those catchments with the largest shifts in flood seasonality. Here, rainfall replaces snowmelt as the dominant FGP primarily due to increasing temperature. We further analysed the ensemble components in contributing to overall uncertainty in the projected changes and found that the climate projections and the methods for downscaling or bias correction tend to be the largest contributors. The relative role of hydrological parameter uncertainty, however, is highest for those catchments showing the largest changes in flood seasonality, which confirms the lack of robustness in hydrological model parameterization for simulations under transient hydrometeorological conditions.

scholarly journals Water Supply for Tongatapu; Past, Present and Future.

2021 ◽  
Author(s):  
◽  
Lopeti Tufui
Keyword(s):  
Water Balance ◽  
Water Supply ◽  
Climate Models ◽  
Climate Model ◽  
Meteorological Data ◽  
Critical Role ◽  
South Pacific Convergence Zone ◽  
Climate Projections ◽  
Enso Cycle ◽  
Freshwater Resource

<p>This thesis presents an investigation of the sustainability of the freshwater aquifer (groundwater) at Tongatapu, the main island of Tonga. Water balance modelling is applied to meteorological data to estimate freshwater recharge at a daily resolution for the period 1980-2018. These results demonstrate a very close coupling between recharge and precipitation but also the critical role played by the ENSO cycle in modulating the supply of freshwater on Tongatapu. They also show that previous water balance modelling for the island, conducted at a monthly resolution, has tended to underestimate the rate of recharge by ~8%.   Historical groundwater extraction rates for Tongatapu are also calculated by compiling monitoring data from operational pumping stations across the island. This shows that extraction rates have increased progressively over the past 50 years and approximately doubled in the last 10 years, as a consequence of increased demand from agriculture, tourism and population growth. Although the freshwater resource appears to be sustainable overall at current rates of supply and demand, there have been sustained periods of zero recharge, notably during strong El Nino events in winter (the dry season).   Climate model projections of future rainfall show that Tonga is situated in a region of great uncertainty, due to shortcomings in our knowledge of how the inability of the models to capture the ENSO cycle will respond to anthropogenic warming, and but moreover, climate models are currently unable to simulate the precise correct positioning of the South Pacific Convergence Zone which strongly influences the amount and seasonal distribution of regional rainfall. Nevertheless, this study also conducted predictive water balance modelling for Tongatapu for the end of the 21st century using the current CMIP5 climate projections for the region under a medium (scenarios RCP4.5) and high (RCP8.5) emissions scenario, in both cases showing substantial reductions in freshwater recharge rates compared to the present. These results raise serious concerns for the future sustainability of Tonga’s freshwater resource, especially if extraction rates continue to increase and salination of the aquifer increases as is highly likely due to sea level rise.   Although Tonga can do little to influence the global climate change mitigation effort, this research highlights the importance of addressing currently resolvable infrastructural problems in water supply and reticulation.</p>

Does a comprehensive evaluation increase confidence in the hydrological model intended for climate impact assessment?

2020 ◽  
Author(s):  
Alexander Gelfan ◽  
Andrei Kalugin ◽  
Inna Krylenko ◽  
Olga Nasonova ◽  
Yeugeniy Gusev ◽  
...  
Keyword(s):  
Hydrological Model ◽  
Climate Model ◽  
Comprehensive Evaluation ◽  
Meteorological Data ◽  
Global Climate Model ◽  
Statistical Significance ◽  
Climate Impact ◽  
Performance Criteria ◽  
Low Flow ◽  
Evaluation Procedure

&lt;p&gt;The objective of the study is to verify a hypothesis that the hydrological model that successfully passed a comprehensive evaluation test is more suitable for impact study than the other model that failed the test. The hypothesis verification is carried out on an example of the physically-based hydrological models ECOMAG and SWAP, which are set up for the two great Arctic basins: the Lena and the Mackenzie rivers. Three versions of every model are compared: (1) the model with a priori assessed parameters (without any calibration); (2) the model calibrated against the streamflow observations at the basin outlets only, and (3) the model calibrated against the streamflow observations at several sites within the basins. The comprehensive evaluation procedure, which includes enhanced tests of model performance and robustness, is applied for all the versions of every model. The performance of the models is compared at multiple sites within the catchments and for multiple hydrological indicators of interest (high flow, low flow, multi-year trends). The robustness of the models is compared through statistical significance of the differences in the performance criteria of the model for climatically contrasting periods composed from the historical meteorological data. From the evaluation results, we identified the preferable (in terms of the assigned criteria) models and established the limits of the models applicability. Then all the compared models, being forced by the Global Climate Model ensemble data, were applied to simulate flow projections for the 21&lt;sup&gt;st&lt;/sup&gt; century and assess the projection uncertainty. The experiment demonstrates that the basin outlet flow projections simulated by the non-calibrated models differ from the projections of the calibrated models in terms of the mean ensemble trajectories and their uncertainty. Thus, under the study conditions (used models, studied basins), we answer &quot;yes&quot; to the question posed in the title of the presentation. &amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document