Challenges in using hydrology and water quality models for assessing freshwater ecosystem services: A review

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.