||Significance, advantages, |
or scientific problems that were solved
1. ||Object oriented model structure
- Dynamic Memory Allocation, saves space and run faster;
- Clearly structured, easy to add new functions and implement new simulation efforts;
- Code reusable and expandable, reduces the size of the program.
2. ||Three dimensional representation
- Three Dimensional watershed objects: nodes, edges, cells, stream, catchment boundary, flowpath.
- Retains all topographical features throughout the model;
- Enables automatic watershed delineation;
- Enables terrain analysis and automate extraction of hydrologic parameters;
- Enables 3-D visualizations.
Vector-based hydrologic watershed modelling
- No restriction on flow directions, flow is directed by the aspect of the cell (element);
- Flows are generated from the cell area instead of from the cell center point;
- Directly uses cell geometric parameters instead of being calculated from nodal points.
- Stream channel network is represented by vector-based segments;
- Water flows into channel segment through the riparian cells which are geometry-defined in vector-based model;
- Water flows into stream segment instead of into channelized elements;
- Directly uses segments geometric parameters instead of calculated from center nodes;
- Enables automated watershed delineation: stream, boundary;
- Enables automated extraction of hydrologic parameters: slope, length, width, aspect, upslope drainage area, upslope cell/segment, downslope cell/segment, neighbor cells, distance to the stream outlet, etc. All these are very difficult to obtaine and manipulate in raster-based models;
- Enables the intergration of of digital terrain information into watershed hydrologic model;
- Enables the application of Equivalent Rectangle Simplification (ERS) (see 5).
4. ||Equivalent Rectangle Simplification (ERS)
- Converts the 2-D flow routing problem into 1-D without changing the element (cell) shape;
- ERS can handle elements (cells) with different shapes and different sizes in hydrologic modeling;
- Provides maximun flexibility to the distributed watershed hydrologic simulation:
The hydrologic model can be coupled to watersheds with a rectangle grid from DEM, or
triangle cells from TIN, or flow-tube cells from TAPES-C or mixtures of cells from
the OWLS automatic delineation model. As long as each cell remains planar, the sizes
and the shapes of the cells can be different from watershed to watershed, or within
5. ||Finite Different Approximation Throughout
- 2-D surface flow and soil flow routing using kinematic wave approximation in association with ERS;
- 2-D macropore flow routing using energy and continuity equation in association with ERS;
- Unconditionally stable and convergent;
- Simulation time steps can be varied without largely changing the simulation results or affecting stability of results.
6. ||Unit compatible
||Allows English or SI unit system for input and output.
7. ||Watershed Macropore Flow Simulation
- Identifies macropore flow from soil flow or surface flow.
- Individual flow generation and routing machinism totally different for surface flow and soil flow.
- Avoids unrealistic amplification of the hydrologic conductivity coefficient or surface water
proportion as often occurs in other models that cover up the natural responses of the soil macropore system.
8. ||Three-Dimensional Visualization
- Enables sky-view of the watershed, as well as a 2-D map view;
- Enables the watershed to be viewed from different angles;
- Enables the watershed to be viewed at different time;
- Enables the watershed to be viewed dynamically;
- Enables the watershed characteristics to be visually presented: contour, soil, topography, flowpaths, flowpath tree, channel network, boundary;
- Enables the simulation result to be visually presented:
(1). Dynamic stream hydrology: stream discharge, stream flow velocity, segment width, segment water depth;
(2). Dynamic watershed hydrology: distribution of cell total flow depths (variable source area), distribution of cell flow components (surface, soil and macropore), distribution of cell water components (canopy water, canopy snow depth, surface water, surface snow depth, soil water depth, soil moisture, macropore pipe water depth), distribution of cell vertical fluxs (canopy ET, surface ET, soil ET, infiltration).
9. ||Two-Dimensional Visualization
- Presents an intergration of system parameters;
- Demonstates hydrologic inputs, simulated and observed discharge (hydrograph);
- Dissects the flow components and water components conditions as a funtion of time over the watershed;
- Provides assistance in model calibration;
- Offers in-depth hydrologic information about the watershed.