|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
THE UNITGRAPH LUMPED TECHNICAL REVIEW AND ANALYSIS MODEL (ULTRA)
1. Purpose and objectives
ULTRA is a simple, user-friendly hydrological model for simulation of urban and rural watersheds. It can be used to generate design hydrographs
from user-supplied input data on basin characteristics, design rainfall,
and special computational control parameters. The model can also be used to
calculate an approximate storage volume required to control the design
hydrograph to a pre-determined release rate.
ULTRA has two rainfall-runoff sub-models: NASHYD for rural basins and STANDHYD for urban basins. Both are lumped conceptual models having simple and limited input requirements.
NASHYD has two main components - unit hydrograph and rainfall losses.The first is based on a cascade of identical linear reservoirs as was proposed by Professor Nash. Two parameters define the shape of the unit hydrograph. Rainfall losses are computed by means of the classical US Soil
STANDHYD also has two components - unit hydrograph and loss function. The unit hydrograph is quasilinear and is similar in shape to a two parallel reservoir conceptual model. This allows a separate simulation of runoff from pervious and impervious areas. The storage coefficient for each reservoir is derived using kinematic wave theory. Losses are estimated for pervious areas from Horton's equation or from an SCS option. The hydrograph from each area is obtained by convolution. The two are then added together to obtain the final runoff hydrograph.
Both sub-models have been extensively tested against measurements and
compared with other, more sophisticated models. ULTRA has a calibration mode to assist in parameter selection. The design mode allows fast simulation of urban and rural design hydrographs for the selected parameters.
Input depends on the selected sub-model. NASHYD requires two parameters to define the shape of the unit hydrograph, along with the event's initial abstraction and curve number. STANDYHD requires the slope, length, surface roughness, depression storage and the impervious area of the basin. Default values for these parameters are available. Both also require the drainage area.
Storms as well as the resulting runoff hydrographs can be stored in order to assess the model parameters. Storms are stored and are used as input to create hydrographs.
The resultant hydrograph can be stored for future reference. Tabular and graphical displays of the hydrograph and hyetograph are available. Simulated and observed hydrographs can be displayed together for
5. Operational requirements and restrictions
The ULTRA model operates on an IBM or compatible personal computer with only 64K of memory. A graphics monitor and a printer facilitate calibration. The model is written in BASIC and is compiled.
6. Form of presentation
Program and documentation in English on a 5.25 inch diskette.
7. Operational experience
ULTRA's sub-models are based on algorithms developed in the PC Interhymo (Otthymo 89) model. The Otthymo 89 model has been applied with
success throughout Canada as well as in basins in Switzerland, Italy,
Spain, Portugal, Cameroon, and the United States of America. It has been applied by over 50 Canadian organizations and is a recommended model in several Canadian guidelines for flood control and storm water management.
8. Originator and technical support
The ULTRA model was developed by J.F. Sabourin at Paul Wisner and
Associates Inc., based on concepts developed by Dr. Paul Wisner and Messrs.
J. P'Ng, A. Lam, and D. Jobin at the University of Ottawa. The originators
will provide technical support.
10. Conditions on use
The ULTRA model is available free-of-charge.
|(First entered: 24 AUG 90||
Last updated: 15 DEC 1999)