scholarly journals Climate change impacts model parameter sensitivity – implications for calibration strategy and model diagnostic evaluation

2021 ◽  
Vol 25 (3) ◽  
pp. 1307-1332
Author(s):  
Lieke Anna Melsen ◽  
Björn Guse
Keyword(s):  
Climate Change ◽  
Hydrological Model ◽  
Climate Change Impacts ◽  
The United States ◽  
Parameter Sensitivity ◽  
Hydrological Models ◽  
The Future ◽  
The Mean ◽  
The Impact

Abstract. Hydrological models are useful tools for exploring the impact of climate change. To prioritize parameters for calibration and to evaluate hydrological model functioning, sensitivity analysis can be conducted. Parameter sensitivity, however, varies over climate, and therefore climate change could influence parameter sensitivity. In this study we explore the change in parameter sensitivity for the mean discharge and the timing of the discharge, within a plausible climate change rate. We investigate whether changes in sensitivity propagate into the calibration strategy and diagnostically compare three hydrological models based on the sensitivity results. We employed three frequently used hydrological models (SAC, VIC, and HBV) and explored parameter sensitivity changes across 605 catchments in the United States by comparing GCM(RCP8.5)-forced historical and future periods. Consistent among all hydrological models and both for the mean discharge and the timing of the discharge is that the sensitivity of snow parameters decreases in the future. Which other parameters increase in sensitivity is less consistent among the hydrological models. In 45 % to 55 % of the catchments, dependent on the hydrological model, at least one parameter changes in the future in the top-5 most sensitive parameters for mean discharge. For the timing, this varies between 40 % and 88 %. This requires an adapted calibration strategy for long-term projections, for which we provide several suggestions. The disagreement among the models on the processes that become more relevant in future projections also calls for a strict evaluation of the adequacy of the model structure for long-term simulations.

scholarly journals Climate change impacts model parameter sensitivity – What does this mean for calibration?

2020 ◽  
Author(s):  
Lieke Anna Melsen ◽  
Björn Guse
Keyword(s):  
Climate Change ◽  
Climate Change Impacts ◽  
The United States ◽  
Parameter Sensitivity ◽  
Model Parameters ◽  
Hydrological Models ◽  
The Future ◽  
Influence Parameter ◽  
Sensitivity Changes ◽  
Sensitive Parameters

Abstract. Hydrological models are useful tools to explore the hydrological impact of climate change. Many of these models require calibration. A frequently employed strategy is to calibrate the five parameters that were found to be most relevant as identified in a sensitivity analysis. However, parameter sensitivity varies over climate, and therefore climate change could influence parameter sensitivity. In this study we explore the change in parameter sensitivity within a plausible climate change rate, and investigate if changes in sensitivity propagate into the calibration strategy. We employed three frequently used hydrological models (SAC, VIC, and HBV), and explored parameter sensitivity changes across 605 catchments in the United States by comparing a GCM-forced historical and future period. Consistent among all models is that the sensitivity of snow parameters decreases in the future. Which parameters increase in sensitivity is less consistent among the models. In 43 % to 49 % of the catchments, dependent on the model, at least one parameter changes in the future in the top-5 most sensitive parameters. The maximum number of changes in the parameter top-5 is two, in 2–4 % of the investigated catchments. The value of the parameters that enter the top-5 cannot easily be identified based on historical data, because the model is not yet sensitive to these parameters. This requires an adapted calibration strategy for long-term projections, for which we provide several suggestions. The disagreement among the models on processes becoming relevant in future projections also calls for a strict evaluation of the adequacy of the model structure and the model parameters implemented therein.

Climate change impacts parameter sensitivity - What does this mean for model calibration?

2020 ◽  
Author(s):  
Lieke Melsen ◽  
Björn Guse
Keyword(s):  
Climate Change ◽  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Parameter Sensitivity ◽  
Rate Of Change ◽  
Hydrological Models ◽  
Global Sensitivity ◽  
The Future ◽  
Sensitive Parameters ◽  
The Impact

<p>Many hydrological models that are used for long term projections require calibration of at least a few parameters. When calibrated on discharge only, a general rule of thumb is that 4 to 5 parameters can be calibrated. The general approach is to conduct a global sensitivity analysis, to determine the four to five most sensitive parameters, and to select these for calibration.</p><p>Parameter sensitivity differs over models, target variables, sensitivity analysis methods, and also over climates. This would also imply that parameter sensitivity could change in a changing climate, and that would interfere with the current standard calibration procedure for hydrological models. Therefore, the question is whether, within a plausible rate of change, climate change propagates into a change in parameter sensitivity.   </p><p>We investigated how parameter sensitivity changes as a consequence of climate change, and if and how this has consequences for the calibration strategy. We applied a hybrid local-global sensitivity analysis method to three frequently used hydrological models (SAC, VIC, and HBV) in 605 basins across the US, and link changes in sensitivity to changes in climate. Finally, we evaluated the impact on the top five most sensitive parameters.</p><p>The results show that in all three models especially snow parameters tend to become less sensitive in the future. However, the models differ in which parameters increase in sensitivity; for some models ET parameters increase, while for others deep layer parameters increase. Evaluating the top 5 most sensitive parameters per basin, we found that in 43% to 49% of the basins at least one parameter changes in the top 5 in the future, while a maximum of two parameter changes in the top 5 was observed over all basins (in 2 to 4% of the basins).</p><p>Overall, the results indicate that in about half of the investigated basins one parameter would have been chosen differently for calibration. If a particular model parameter is, within the current climate, not or hardly sensitive to discharge, it is not possible to calibrate this parameter – notwithstanding whether this parameter becomes sensitive in the future. Therefore, the consequence of these results is that for parameters that will become sensitive in the future, a range of feasible parameter values have to be sampled for future projections, thereby capturing predictive uncertainty as a consequence of changing sensitivities.</p>

scholarly journals Epidemic malaria and warmer temperatures in recent decades in an East African highland

2010 ◽  
Vol 278 (1712) ◽  
pp. 1661-1669 ◽  
Author(s):  
David Alonso ◽  
Menno J. Bouma ◽  
Mercedes Pascual
Keyword(s):  
Climate Change ◽  
East Africa ◽  
Nonlinear Response ◽  
Climate Change Impacts ◽  
Human Model ◽  
Recent Past ◽  
East African ◽  
Highly Nonlinear ◽  
The Impact

Climate change impacts on malaria are typically assessed with scenarios for the long-term future. Here we focus instead on the recent past (1970–2003) to address whether warmer temperatures have already increased the incidence of malaria in a highland region of East Africa. Our analyses rely on a new coupled mosquito–human model of malaria, which we use to compare projected disease levels with and without the observed temperature trend. Predicted malaria cases exhibit a highly nonlinear response to warming, with a significant increase from the 1970s to the 1990s, although typical epidemic sizes are below those observed. These findings suggest that climate change has already played an important role in the exacerbation of malaria in this region. As the observed changes in malaria are even larger than those predicted by our model, other factors previously suggested to explain all of the increase in malaria may be enhancing the impact of climate change.

Cultural Pluralism and the Future of American Unity: The Impact of Illegal Aliens

1984 ◽  
Vol 18 (3) ◽  
pp. 800-813
Author(s):  
Lawrence H. Fuchs
Keyword(s):  
United States ◽  
The United States ◽  
Cultural Pluralism ◽  
Illegal Migration ◽  
Political Unity ◽  
The Future ◽  
Long Term Impact ◽  
The Impact ◽  
Special Notice

This essay explores the question of the impact of illegal migration on American unity and cultural pluralism in the United States. Assuming that over time the descendents of undocumented workers now in the United States will behave substantially like descendants of those who immigrate legally, the author concludes that the long-term impact of illegal migration barely will be noticeable provided it is reduced substantially in the future. The process of acculturation will work in the same way for both groups as it has for other ethnic groups in the past, given comparable levels of education and length of family residence in the United States. The author takes special notice of the illegal migration of Spanish-speaking workers and hypothesizes that the behavior of their descendants will not differ from the descendants of other immigrants, legal or illegal, in ways that disrupt fundamental patterns of American political unity and cultural pluralism.

scholarly journals Caring for the future can turn tragedy into comedy for long-term collective action under risk of collapse

2020 ◽  
Vol 117 (23) ◽  
pp. 12915-12922 ◽  
Author(s):  
Wolfram Barfuss ◽  
Jonathan F. Donges ◽  
Vítor V. Vasconcelos ◽  
Jürgen Kurths ◽  
Simon A. Levin
Keyword(s):  
Climate Change ◽  
Collective Action ◽  
Experimental Testing ◽  
The Public ◽  
Regime Changes ◽  
The Future ◽  
The Commons ◽  
Future Outcomes ◽  
The Impact

We will need collective action to avoid catastrophic climate change, and this will require valuing the long term as well as the short term. Shortsightedness and uncertainty have hindered progress in resolving this collective action problem and have been recognized as important barriers to cooperation among humans. Here, we propose a coupled social–ecological dilemma to investigate the interdependence of three well-identified components of this cooperation problem: 1) timescales of collapse and recovery in relation to time preferences regarding future outcomes, 2) the magnitude of the impact of collapse, and 3) the number of actors in the collective. We find that, under a sufficiently severe and time-distant collapse, how much the actors care for the future can transform the game from a tragedy of the commons into one of coordination, and even into a comedy of the commons in which cooperation dominates. Conversely, we also find conditions under which even strong concern for the future still does not transform the problem from tragedy to comedy. For a large number of participating actors, we find that the critical collapse impact, at which these game regime changes happen, converges to a fixed value of collapse impact per actor that is independent of the enhancement factor of the public good, which is usually regarded as the driver of the dilemma. Our results not only call for experimental testing but also help explain why polarization in beliefs about human-caused climate change can threaten global cooperation agreements.

scholarly journals An ensemble approach to assess hydrological models' contribution to uncertainties in the analysis of climate change impact on water resources

2013 ◽  
Vol 17 (2) ◽  
pp. 565-578 ◽  
Author(s):  
J. A. Velázquez ◽  
J. Schmid ◽  
S. Ricard ◽  
M. J. Muerth ◽  
B. Gauvin St-Denis ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Climate Models ◽  
Hydrological Model ◽  
Global Climate ◽  
Regional Climate ◽  
Structural Complexity ◽  
Global Climate Models ◽  
Hydrological Models ◽  
The Impact

Abstract. Over the recent years, several research efforts investigated the impact of climate change on water resources for different regions of the world. The projection of future river flows is affected by different sources of uncertainty in the hydro-climatic modelling chain. One of the aims of the QBic3 project (Québec-Bavarian International Collaboration on Climate Change) is to assess the contribution to uncertainty of hydrological models by using an ensemble of hydrological models presenting a diversity of structural complexity (i.e., lumped, semi distributed and distributed models). The study investigates two humid, mid-latitude catchments with natural flow conditions; one located in Southern Québec (Canada) and one in Southern Bavaria (Germany). Daily flow is simulated with four different hydrological models, forced by outputs from regional climate models driven by global climate models over a reference (1971–2000) and a future (2041–2070) period. The results show that, for our hydrological model ensemble, the choice of model strongly affects the climate change response of selected hydrological indicators, especially those related to low flows. Indicators related to high flows seem less sensitive on the choice of the hydrological model.

Simulating the impact of future climate change on runoff processes in selected catchments of Slovakia

2021 ◽  
Author(s):  
Roman Výleta ◽  
Milica Aleksić ◽  
Patrik Sleziak ◽  
Kamila Hlavcova
Keyword(s):  
Climate Change ◽  
Air Temperature ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Future Climate Change ◽  
Time Horizons ◽  
The Future ◽  
The Impact ◽  
Impacts Of Climate Change

<p>The future development of the runoff conditions, as a consequence of climate change, is of great interest for water managers. Information about the potential impacts of climate change on the hydrological regime is needed for long-term planning of water resources and flood protection.</p><p>The aim of this study is to evaluate the possible impacts of climate change on the runoff regime in five selected catchments located in the territory of Slovakia. Changes in climatic characteristics (i.e., precipitation and air temperature) for future time horizons were prepared by a regional climate model KNMI using the A1B emission scenario. The selected climatic scenario predicts a general increase in air temperature and precipitation (higher in winter than in summer). For simulations of runoff under changed conditions, a lumped rainfall-runoff model (the TUW model) was used. This model belongs to a group of conceptual models and follows a structure of a widely used Swedish HBV model. The TUW model was calibrated for the period of 2011 – 2019. We assumed that this period would be similar (to recent/warmer climate) in terms of the average daily air temperatures and daily precipitation totals. The future changes in runoff due to climate change were evaluated by comparing the simulated long-term mean monthly runoff for the current state (1981-2010) and modelled scenarios in three time periods (2011-2040, 2041-2070, and 2071-2100). The results indicate that changes in the long-term runoff seasonality and extremality of hydrological cycle could be expected in the future. The runoff should increase in winter months compared to the reference period. This increase is probably related to a rise in temperature and anticipated snowmelt. Conversely, during the summer periods, a decrease in the long-term runoff could be assumed. According to modelling, these changes will be more pronounced in the later time horizons.</p><p>It should be noted that the results of the simulation are dependent on the availability of the inputs, the hydrological/climate model used, the schematization of the simulated processes, etc. Therefore, they need to be interpreted with a sufficient degree of caution</p>

Analysis of Ideal Directions of Climate Change Adaptation and Problems in Implementing Them for Local Japanese Governments

2015 ◽  
Vol 10 (3) ◽  
pp. 420-428 ◽  
Author(s):  
Nobuo Shirai ◽  
◽  
Mitsuru Tanaka
Keyword(s):  
Climate Change ◽  
Climate Change Adaptation ◽  
Local Governments ◽  
Climate Change Impacts ◽  
Adaptive Governance ◽  
Subject Formation ◽  
Adaptation Measures ◽  
Research Level ◽  
The Future

Additional adaptation measures such as “basic improvement of sensitivity” and “adaptive governance against mid and long term impacts” are set as ideal directions for local governments. The study of the situations for implementing additional adaptation measures by local governments were determined by using checklists. It is clarified as a result that additional adaptation measures have not been considered enough. The following problems in implementing measures from the “Japan local Forum for Climate Change Adaptation Society” were found: (1) Prediction and evaluation of climate change impacts, (2) Concretization and evaluation of adaptation measures, (3) Communication and subject formation and (4) Implementation of the measures and preparation of conditions. In the future, it is necessary to concretize additional adaptation measures at the research level, to share these additional adaptation measures with concerned parties and to promote the exchange of opinions.

Modeling the impact of 1.5 and 2.0◦C global warming on the hydrology of the Faleme river basin (West Africa)

2020 ◽  
Author(s):  
Mamadou Lamine Mbaye ◽  
Khadidiatou Sy ◽  
Bakary Faty ◽  
Saidou Moustapha Sall
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Water Resources ◽  
West Africa ◽  
Hydrological Model ◽  
Cumulative Distribution ◽  
Economic Activities ◽  
Calibration And Validation ◽  
The Future ◽  
The Impact

<p>Climate change raises many questions about the future availability of water resources in West Africa. Indeed, water in this region is a fundamental element for many socio-economic activities. This study proposes an assessment of the impact of climate change on the hydrology of the Faleme basin, located in the Sahel (West Africa). The applied methodology consists in calibrating and validating the hydrological model GR4J before simulating the future evolution of flows in this catchment under of 1.5 and 2°C global warming.  Observed rainfall, potential evapotranspiration (PET), and river flows were used for calibration and validation of the GR4J model. Furthermore, output of three regional climate models (DMI-HIRHAM, SHIM-RCA, and BCCR-WRF) were bias corrected with the cumulative distribution function-transform (CDF-t) before used as input to the GR4J hydrological model to simulate future flows at the watershed scale. During the historical period the results shows a good correspondence between the simulated flows and those observed during calibration and validation, with Nash–Sutcliffe efficiencies (NSE) greater than 70%. Projections show a general increase in mean annual temperature and PET; a decrease in mean annual rainfall is projected by the DMI-HIRHAM, BCCR-WRF models and the overall mean; while a slight increase is noted with the SMHI-RCA model. As for future flows, a downward trend in annual and monthly average flows is expected in the two sub-basins of the Faleme (Kidira and Gourbassi) with input from the DMI-HIRHAM, BCCR-WRF models and the overall mean; however,  the GR4J forced by the SMHI-RCA model output, project increased flows. Furthermore, the decrease is more pronounced at Gourbassi sub-basin than at Kidira sub-basin. Thus, recommendations were made to mitigate the likely impacts of climate change on socio-economic activities that use water resources.</p>

scholarly journals An ensemble approach to assess hydrological models' contribution to uncertainties in the analysis of climate change impact on water resources

2012 ◽  
Vol 9 (6) ◽  
pp. 7441-7474 ◽  
Author(s):  
J. A. Velázquez ◽  
J. Schmid ◽  
S. Ricard ◽  
M. J. Muerth ◽  
B. Gauvin St-Denis ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Climate Models ◽  
Hydrological Model ◽  
Regional Climate ◽  
Structural Complexity ◽  
Regional Climate Models ◽  
Hydrological Models ◽  
Distributed Models ◽  
The Impact

Abstract. Over the recent years, several research efforts investigated the impact of climate change on water resources for different regions of the world. The projection of future river flows is affected by different sources of uncertainty in the hydro-climatic modelling chain. One of the aims of the QBic3 project (Québec-Bavarian International Collaboration on Climate Change) is to assess the contribution to uncertainty of hydrological models by using an ensemble of hydrological models presenting a diversity of structural complexity (i.e. lumped, semi distributed and distributed models). The study investigates two humid, mid-latitude catchments with natural flow conditions; one located in Southern Québec (Canada) and one in Southern Bavaria (Germany). Daily flow is simulated with four different hydrological models, forced by outputs from regional climate models driven by a given number of GCMs' members over a reference (1971–2000) and a future (2041–2070) periods. The results show that the choice of the hydrological model does strongly affect the climate change response of selected hydrological indicators, especially those related to low flows. Indicators related to high flows seem less sensitive on the choice of the hydrological model. Therefore, the computationally less demanding models (usually simple, lumped and conceptual) give a significant level of trust for high and overall mean flows.

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