The river components in Earth System Models (ESMs) have traditionally been simplified, with the primary purpose of delivering runoff generated from the land model to the ocean. This approach has been largely effective due to the historically coarse spatial resolution of ESMs and their inadequate representation of natural hydrologic processes and human activities. However, as modern ESMs shift towards higher spatial resolution and more accurate representation of human dimensions, it becomes increasingly important to incorporate river dynamics processes within ESMs.

This work highlights the recent progress in the MOSART (Model for Scale Adaptive River Transport) river model within the E3SM (Energy Exascale Earth System Model), emphasizing three key areas. First, it explores the interplay between river flooding and water management. We examine the impact of water management on global river flooding using a refined flood inundation scheme in MOSART which allows for more accurate predictions and assessments of flood inundation area. Second, a new inter-basin transport scheme that enables water transfers outside of the basin. A case study on the Delaware River Basin demonstrates this scheme, which is based on an advanced unstructured river mesh with river network and dam locations embedded. This development is crucial for understanding regional hydrology and water resource distribution. Third, a new diagnostic tool extends the current E3SM-diags to focus on MOSART outputs. This tool allows users to analyze time series data at river gauge locations through interactive maps, enhancing the ability to evaluate and interpret the river model outputs.