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The ecological integrity of freshwater ecosystems is intimately linked to natural fluctuations in the river flow regime. In catchments with little human-induced alterations of the flow regime (e.g. abstractions and regulations), existing hydrological models can be used to predict changes in the local flow regime to assess any changes in its rivers' living environment for endemic species. However, hydrological models are traditionally calibrated to give a good general fit to observed hydrographs, e.g. using criteria such as the Nash–Sutcliffe efficiency (NSE) or the Kling–Gupta efficiency (KGE). Much ecological research has shown that aquatic species respond to a range of specific characteristics of the hydrograph, including magnitude, frequency, duration, timing, and the rate of change of flow events. This study investigates the performance of specially developed and tailored criteria formed from combinations of those specific streamflow characteristics (SFCs) found to be ecologically relevant in previous ecohydrological studies. These are compared with the more traditional Kling–Gupta criterion for 33 Irish catchments. A split-sample test with a rolling window is applied to reduce the influence on the conclusions of differences between the calibration and evaluation periods. These tailored criteria are shown to be marginally better suited to predicting the targeted streamflow characteristics; however, traditional criteria are more robust and produce more consistent behavioural parameter sets, suggesting a trade-off between model performance and model parameter consistency when predicting specific streamflow characteristics. Analysis of the fitting to each of 165 streamflow characteristics revealed a general lack of versatility for criteria with a strong focus on low-flow conditions, especially in predicting high-flow conditions. On the other hand, the Kling–Gupta efficiency applied to the square root of flow values performs as well as two sets of tailored criteria across the 165 streamflow characteristics. These findings suggest that traditional composite criteria such as the Kling–Gupta efficiency may still be preferable over tailored criteria for the prediction of streamflow characteristics, when robustness and consistency are important.
Thibault Hallouin; Michael Bruen; Fiachra E. O'Loughlin. Calibration of hydrological models for ecologically relevant streamflow predictions: a trade-off between fitting well to data and estimating consistent parameter sets? Hydrology and Earth System Sciences 2020, 24, 1031 -1054.
AMA StyleThibault Hallouin, Michael Bruen, Fiachra E. O'Loughlin. Calibration of hydrological models for ecologically relevant streamflow predictions: a trade-off between fitting well to data and estimating consistent parameter sets? Hydrology and Earth System Sciences. 2020; 24 (3):1031-1054.
Chicago/Turabian StyleThibault Hallouin; Michael Bruen; Fiachra E. O'Loughlin. 2020. "Calibration of hydrological models for ecologically relevant streamflow predictions: a trade-off between fitting well to data and estimating consistent parameter sets?" Hydrology and Earth System Sciences 24, no. 3: 1031-1054.
Thibault Hallouin. Authors' Reply to the Referees' Comments. 2019, 1 .
AMA StyleThibault Hallouin. Authors' Reply to the Referees' Comments. . 2019; ():1.
Chicago/Turabian StyleThibault Hallouin. 2019. "Authors' Reply to the Referees' Comments." , no. : 1.
Thibault Hallouin; Michael Bruen; Fiachra E. O'loughlin. Supplementary material to "Calibration of hydrological models for ecologically-relevant streamflow predictions: a trade-off between performance and consistency". 2019, 1 .
AMA StyleThibault Hallouin, Michael Bruen, Fiachra E. O'loughlin. Supplementary material to "Calibration of hydrological models for ecologically-relevant streamflow predictions: a trade-off between performance and consistency". . 2019; ():1.
Chicago/Turabian StyleThibault Hallouin; Michael Bruen; Fiachra E. O'loughlin. 2019. "Supplementary material to "Calibration of hydrological models for ecologically-relevant streamflow predictions: a trade-off between performance and consistency"." , no. : 1.
The ecological integrity of freshwater ecosystems is intimately linked to natural fluctuations in the river flow regime. Anthropogenic alterations in flow regimes threaten water security and freshwater biodiversity in many regions of the world. The impacts of climate change on the hydrological cycle change local flow regimes and thus impact on the ecological systems. In catchments with little human-induced hydro-morphological changes, existing hydrological models can be used to predict changes in local flow regime in order to assess whether its rivers remain a suitable living environment for endemic species. However, hydrological models are traditionally calibrated to give a good general fit between observed and simulated hydrographs, e.g., using an optimisation with an objective function such as the Nash-Sutcliffe, or the Kling–Gupta efficiencies. Much ecological research has shown that aquatic species respond to very specific characteristics of the hydrograph, whether magnitude, frequency, duration, timing, and rate of change of flow events. Since each community in a river may be particularly sensitive to a few very specific streamflow characteristics, alternative hydrological model calibration strategies are needed, focussing on good performance for those specific characteristics. This study investigates the performance of a set of specially developed, bespoke, objective functions made of combinations of specific streamflow characteristics relevant for fish and invertebrate communities. These are compared with the more traditional objective functions on a set of 33 Irish catchments with little human regulation. A split-sample test with a rolling-window procedure is applied to reduce the influence of variations between the calibration/evaluation periods on the conclusions. These bespoke objective functions are shown to be better suited to predict the targetted streamflow characteristics in terms of performance in evaluation; however, traditional objective functions yield more consistent behavioural parameter sets, indicating a trade-off between model performance and model consistency when predicting streamflow characteristics, especially when the number of target streamflow characteristics are low.
Thibault Hallouin; Michael Bruen; Fiachra E. O'loughlin. Calibration of hydrological models for ecologically-relevant streamflow predictions: a trade-off between performance and consistency. Hydrology and Earth System Sciences Discussions 2019, 1 -31.
AMA StyleThibault Hallouin, Michael Bruen, Fiachra E. O'loughlin. Calibration of hydrological models for ecologically-relevant streamflow predictions: a trade-off between performance and consistency. Hydrology and Earth System Sciences Discussions. 2019; ():1-31.
Chicago/Turabian StyleThibault Hallouin; Michael Bruen; Fiachra E. O'loughlin. 2019. "Calibration of hydrological models for ecologically-relevant streamflow predictions: a trade-off between performance and consistency." Hydrology and Earth System Sciences Discussions , no. : 1-31.
Freshwater ecosystems contribute to many ecosystem services, many of which are being threatened by human activities such as land use change, river morphological changes, and climate change. Many disciplines have studied the processes underlying freshwater ecosystem functions, ranging from hydrology to ecology, including water quality, and a panoply of models are available to simulate their behaviour. This understanding is useful for the prediction of ecosystem services, but the model outputs must go beyond the production of time-series of biophysical variables, and must facilitate the beneficial use of the information it contains about the ecosystem services it describes. This article analyses the literature of ad hoc approaches that aim at quantifying one or more freshwater ecosystem services. It identifies the strategies adopted to use disciplinary-specific models for the prediction of the services. This review identifies that hydrological, water quality, and ecological models form a valuable knowledge base to predict changes in ecosystem conditions, but challenges remain to make proper and fruitful use of these models. In particular, considerations of temporal and spatial scales could be given more attention in order to provide better justifications for the choice of a particular model over another, including the uncertainty in their predictions.
Thibault Hallouin; Michael Bruen; Mike Christie; Craig Bullock; Mary Kelly-Quinn. Challenges in Using Hydrology and Water Quality Models for Assessing Freshwater Ecosystem Services: A Review. Geosciences 2018, 8, 45 .
AMA StyleThibault Hallouin, Michael Bruen, Mike Christie, Craig Bullock, Mary Kelly-Quinn. Challenges in Using Hydrology and Water Quality Models for Assessing Freshwater Ecosystem Services: A Review. Geosciences. 2018; 8 (2):45.
Chicago/Turabian StyleThibault Hallouin; Michael Bruen; Mike Christie; Craig Bullock; Mary Kelly-Quinn. 2018. "Challenges in Using Hydrology and Water Quality Models for Assessing Freshwater Ecosystem Services: A Review." Geosciences 8, no. 2: 45.