Abstract
Abstract. The simulation of routing and distribution of water through a regulated river system with a river management model will quickly result in complex and nonlinear model behaviour. A robust sensitivity analysis increases the transparency of the model and provides both the modeller and the system manager with a better understanding and insight on how the model simulates reality and management operations. In this study, a robust, density-based sensitivity analysis, developed by Plischke et al. (2013), is applied to an eWater Source river management model. This sensitivity analysis methodology is extended to not only account for main effects but also for interaction effects. The combination of sensitivity indices and scatter plots enables the identification of major linear effects as well as subtle minor and nonlinear effects. The case study is an idealized river management model representing typical conditions of the southern Murray–Darling Basin in Australia for which the sensitivity of a variety of model outcomes to variations in the driving forces, inflow to the system, rainfall and potential evapotranspiration, is examined. The model outcomes are most sensitive to the inflow to the system, but the sensitivity analysis identified minor effects of potential evapotranspiration and nonlinear interaction effects between inflow and potential evapotranspiration.
Highlights
Water managers rely heavily on models to predict future water availability, optimize water use and evaluate water management strategies in order to find a balance between environmental, social and economic demands on the system
The sensitivity analysis of the hypothetical river management model highlights inflow as a crucial variable of the model and how this affects the economic, environmental and sociological functions of the river. This emphasizes the importance of an accurate characterization of the flow rates of upstream areas when modelling flow routing in regulated systems comparable to the case study, i.e. the regulated river systems of the Murray–Darling Basin in Australia
The interaction effect of Inflow and PET is mostly due to the feedback mechanism as irrigation requirements increase with increasing potential evapotranspiration
Summary
Water managers rely heavily on models to predict future water availability, optimize water use and evaluate water management strategies in order to find a balance between environmental, social and economic demands on the system. In recent decades, addressing this issue has been the focus of much research in hydrological model calibration and predictive uncertainty analysis (Gupta et al, 2012). The knowledge gained from such sensitivity analysis is of relevance during model development, it provides added value to the model as it can focus management and monitoring to those aspects of the system and model that are most important to the management of water resources (Saltelli et al, 2008). Discussing model sensitivities with stakeholders will remove the notion of the model being a “black box” and can provide stakeholders with a better appreciation of the accuracy of the model, which has proven to be a key aspect of adoption of model results by management (Patt, 2009; Bark et al, 2013)
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