MOHID Land is the newest core executable of the MOHID Water Modelling System. This program is designed to simulate hydrographic basin and aquifers.
Mohid Land Modules
Some modules developed are related with specific processes which occur inside a watershed. Examples are:
- Module Runoff which calculates overland runoff;
- Module DrainageNetwork which handles water routing inside rivers
- Module PorousMedia which calculates infiltration, unsaturated and saturated water movement
- Module PorousMediaProperties which calculates property transport in soil (under development)
- Module Vegetation which accounts for vegetation in terms of evapotranspiration and initial loss
- Module Basin which handles information between modules and computes interface forcing fluxes between atmosphere and soil (e.g. troughfall, potential evapotranspiration, etc.).
See below how you can see module source code.
MOHID Land's main features
- Drainage Network (Cinematic and Dynamic Wave);
- 2D Overland Flow
- Linkage to MOHID Water by Module Discharges
- Basin Management
Dynamical time step adaptation
MOHID Land uses an adaptive time-stepping method in its main hydrodynamic cycle. Within an iterative cycle, if the water volume — of reach or overland flow or porous media — varies more than a user defined percentage during two consecutive time steps, the model automatically decreases the time step. Thereafter the model recalculates the current solution with a smaller time step for the affected process (reach or overland flow or porous media). This process is repeated until the volume variation is less than the user defined value mentioned above. The time step dynamically increases again when the model verifies that flow is “stable”. For example within the module "Drainage Network" the time step may be reduced to very short intervals during flush events. This procedure avoids the occurrence of negative volumes and optimizes the time it takes to make a certain simulation, without compromising model stability. Time steps of the processes — computed in the different sub-models — can be chosen differently, adding more to the optimization of the computational cost.
GIS Model Interfaces
You can download interfaces to prepare inputs and to analyse model results. Presently available two options:
- a completly free interface from Mohid Website (www.mohid.com).
- a beta version of a new interface can be downloaded from Action Modulers.
You can produce spatialy interpolated rain using FillMatrix tool, using as input two or more precipitation stations.
You can download the latest source code of the model from Codeplex (Mohid Land in CodePlex). Just click on the download link, no need to register. For advanced users you can download the entire solution ready to compile.
Other users can just browse around the code of each module to checkout equations. In the links below you can go directly to the version from 4 Feb 2011 and see code in html:
- Mohid Land Is the Main Program of Mohid Land
- Module Basin Is the top level of RunOff, Infiltration, River Flow and Vegetation
- Module Porous Media Simulates Water Flow in variable saturated soils
- Module Porous Media Properties Deals with all property transport in Porous Media.
- Module Sediment Quality Zero-dimensional model for primary production, nitrogen and carbon cycle in the Porous Media Soil and Aquifer)
- Module PhreeqC Zero-dimensional model for chemistry equilibrium of solution, pure phases, gas phase, solid phase, exchangers and surfaces in Porous Media (Soil and Aquifer)
- Module Run Off Module which calculates the Surface RunOff
- Module Run Off Properties Deals with all property transport in Runoff
- Module Vegetation Module to simulate plant development
- Module Drainage Network Module which simulates a 1D Drainage Network System
- Mohid River Network Program that alows to run river using SWAT-Mohid discharges
- Module CEQUALW2 U.S. Army Corps of Engineers zero-dimensional model for primary production that can be run to simulate water quality in the river
- Module Triangulation This is one of the modules for interpolation. This is useful to obtain distributed rain in space based on point time series.