A rigorous analytical hydrological model for Ensemble Rainfall-Runoff Analysis (ERRA) of catchments. The paper gives the concepts, mathematical details and several proof-of-concepts. ERRA was designed as a tool for iterative and exploration of hydrological data, through trial and error with analyses of varying degrees of complexity. The broad geosciences community could benefit from this statistical approach. The discussion cites some good examples of applications possible in hydrology, but potential also in other related fields as well.

The paper includes a very rare 3 year data collection of stable water isotopes in surface and subsurface waters. The innovative analysis challenge general conceptualizations of new precipitation inputs wetting dry soils or displacing previously stored waters from those soils. These observations illustrate how measurements of isotopic variability across different subsurface depths, hillslope positions, and time scales can help to constrain potential flow processes delivering precipitation to deep soils and streams.

Large sample hydrology datasets such as Caravan provides the community with hydrometeorological information and catchment attributes for many catchments in the world and offers the opportunity for hydrological research. However, there are considerable differences between the forcing data of Caravan compared to the CAMELS datasets, especially with potential evaporation. This can lead to wrong conclusions on catchment hydrological drivers and affect regionalization. This papers shows the important of robustness of large sample datasets and the need to keep assessing that.