**2. The Basin Futures Platform**

The Basin Futures platform was designed based on the needs expressed by catchment managers, policymakers, environmental groups, and scientists. It is designed to lower the barrier to entry for conducting initial assessments of basin water resources and explore future development scenarios. Basin Futures leverages existing data (global and local) to empower decision-makers to understand their opportunities and constraints in managing water resources [21]. The platform integrates global data with models, all packaged in a web application with readily available cloud processing. This reduces costs on multiple fronts: data integration, model setup and integration, and infrastructure. This setup allows quick range-finding scenarios to be run, providing an explorative tool to aid water resource planning discussion. Basin Futures currently has two main modelling components: rainfall-runoff via GR4J [22] to generate the runoff in a basin, and a custom-built reach model for undertaking water management and transfer activities such as water storage, hydropower generation, routing of flows through the basin, demands/consumption and crop modelling (Figure 1). Basin water balance is produced on a daily basis but lumped monthly, with outputs able to be reported on a monthly or annual scale. Future scenarios are able to be run to explore climate change and changing population scenarios. Basin Futures uses climate scenarios based on The Inter-Sectoral Impact Model Inter-comparison Project (ISIMIP) outputs [23]. Enabling users to plan for climate resilient basins by assessing the

potential changes in the quantity and timing of runoff, precipitation and streamflow based on multiple future climate scenarios.

**Figure 1.** Conceptualisation of the reach model engine underlying Basin Futures.

Our approach focusses on three aspects: global application, easy development of scenarios, and a lower barrier to entry. These key aspects are where Basin Futures differs from existing systems, such as those focused on specific water management areas such as flood forecasting [24,25]. Our approach is similar to a recent web implementation of the Soil and Water Assessment Tool (SWAT) Online [26]; however, we provide scenario development and result assessment. Basin Futures supports users with a robust yet simple modelling framework and can provide a pathway to more sophisticated products through export capabilities. The model workflow provides a consistent and repeatable process of

basin water assessments for any basin across the globe (Figure 2). Basin Futures provides an enabling environment for planning, cooperation and participation in water management.

**Figure 2.** User workflow within Basin Futures.
