Cascade predicts river water quality at catchment scale. It is used by researchers when fine-scale space and time resolution (50 metres; 30 minutes) is needed for research or to inform water management options.
Cascade is a dynamic, process-based model that predicts water quality across whole catchments at very fine resolution (every 50 metres and 30 minutes). It computes hydrological response unit (HRU) outputs to rivers in parallel, tracks particles, and separates wave speed from velocity so that water quality variables do not move at the same speed as a flood wave. The delivery of nutrients to rivers from the soil allows varying concentrations according to hydrological conditions, using a three-layer non-linear storage model. The capabilities of Cascade have been used to provide the fine-scale boundary conditions that coastal marine models need, and to describe detailed trajectories of pathogens from sewage works on the river Conwy.
Cascade was developed under the NERC Macronutrients programme (2013-2015), building on earlier simpler models, to represent the Conwy catchment. It was then applied to the Halladale and Tamar catchments in the NERC Locate project (2016-2021) in "lite" form, and can be developed for any catchment.
Cascade is unique among water quality models in:
(1) the fine scale at which it operates;
(2) the computational techniques used to achieve this (including particle tracking);
(3) the separation of wave speed and water velocity; and
(4) the treatment of water quality entering rivers from the soil, using variable concentrations according to hydrological conditions
Cascade was developed by UKCEH.
Cascade is open access: available to use at no cost via the NERC JASMIN facility. User guidance is available by request to the model owner.
Development of Cascade was funded by the NERC Macronutrients programme (Turf-to-Surf project). Its application was funded by UKRI-NERC National Capability (LOCATE programme) and Viraqua research project.