| Abstract |
The Dynamic Environmental Sensitivity to Change (DESC) project coupled cellular automaton (CA) modelling from various backgrounds and produced the CAESAR-Lisflood-DESC (CLiDE) modelling platform: a geomorphological simulator that allows a variety of Earth system interactions to be explored. A derived version of the well established Cellular Automaton Evolutionary Slope and River (CAESAR) model (Coulthard and Van De Wiel, 2006), CAESAR-Lisflood, which incorporates the Lisflood hydrodymanic model (Coulthard et al., 2013) to simulate channel and overbank flow, is used as the platform kernel. The two dimensional modular design allows great versatility in the range of simulated spatio-temporal scales to which it can be applied. CAESAR has been used to investigate a variety of sediment transport, erosional and depositional processes under differing climatic and land use pressures in river reaches and catchments (Hancock et at., 2011). The recent addition of Lisflood to the code improves the representation of surface water flow within the model by incorporating momentum. However, as with many landscape evolution models (LEMs), CAESAR over-simplifies the representation of some of the hydrological processes and interactions that drive sediment transport. Specifically, it does not simulate groundwater flow and its discharge to rivers. To address these limitations, the non-Lisflood controlled surface hydrological processes within the CLiDE platform are replaced with a bespoke distributed hydrological model that includes a groundwater model. This hydrological model partitions rainfall between surface run-off and recharge to groundwater using a soil water balance model, which is applied at each grid cell. To simulate groundwater flow to river channels we incorporate a single layer finite difference model into the code. This solves the governing partial differential groundwater flow equation using a forward time-stepping, or explicit, solution method (Wang and Anderson, 1982), which can be considered as a cellular automaton (CA) model (Ravazzani et al., 2011). The groundwater model is coupled to the surface model through the exchange of recharge and baseflow. In addition to the hydrological modifications, a debris flow component has been added to the platform. The triggering aspect of this component is linked to simulated groundwater levels. |
