Seminar on Hydrological modelling
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The document outlines a seminar on hydrological modeling, focusing on the HEC-RAS model, which is used for channel flow analysis and floodplain management by hydraulic engineers. It discusses the types of hydrological models (lumped, semi-distributed, and distributed), their uses, advantages, and limitations. The HEC-RAS model is highlighted for its user-friendly interface and functionalities, including steady and unsteady flow simulations, though it has certain constraints such as accuracy in large data and steep slopes.
Seminar on Hydrological modelling
- 1. Prepared By: VISHVAM PANCHOLI (130280712013) ME-Water Resources & Management L.D.College of Engineering,Ahmedabad-380061
- 2. Outline of seminar *Basic Concept of modelling *Introduction of modelling *Introduction to HEC RAS Model *Overview of HEC RAS Model
- 4. Hydrologic models are simplified, conceptual representations of the Hydrologic cycle. Source:- U.S.D.S
- 5. Why Modelling is Required ? Modelling has become an integral part of the decision making process for water engineers and managers. Recent research in hydrologic modelling tries to have a more global approach to the understanding of the behaviour of hydrologic systems to make better predictions and to face the major challenges in water resources management. Recently, Hydrological models have taken over the most important tasks in problem solving in hydrology (UNESCO, 1985). It is valuable for studying potential impacts of changes in land use or climate. As one report of CSDMS ( Community Surface Dynamics Modelling System) 56 Hydrological models are Present.
- 6. What are the use of a model? Forecast / Prediction Instead of expensive and time consuming measurements What happens if’ questions Summarize and test knowledge Education
- 9. 1).Lumped models Do not account for the spatial distribution of input variables or parameters. Do not require a digital elevation model (DEM) as input. Also Known as “Low Rank” Models. Ex- SRM (Snowmelt-Runoff Model), WATBAL etc. 2).Semi-distributed models Models Parameters are partially vary in space by dividing the basin into sub basins. It has Two types 1) Kinematic wave theory models (KW models, such as HEC-HMS), 2) Probability distributed models (PD models, such as TOPMODEL).
- 10. The KW models are simplified versions of the surface and/or subsurface flow equations The PD models are accounted distributions of input parameters across the basin. Also Known as “Medium Rank” Models. Ex-HEC-HMS,HEC-RAS, Storm Water Management Model (SWMM), TOPMODEL. 3).Distributed models Parameters are fully allowed to vary in space. It require large amounts of (often unavailable) data. Distributed models require a DEM as input. Also Known as “High Rank” Models. EX-MIKE11/SHE, WATFLOOD etc.
- 11. Introduction to HEC RAS
- 12. HEC-RAS (Hydrologic Engineering Centers River Analysis System) HEC-RAS is a one-dimensional flow hydraulic model designed to aid hydraulic engineers in channel flow analysis and floodplain determination. HEC-RAS program was developed by the US Army Corps of Engineers to manage the rivers, harbors,other public works under their jurisdiction.
- 13. HEC-RAS model offering a simple way to set model parameters and a graphical user interface(GUI) to run the model and visualize the results. River Analysis Water depth Flow
- 14. Use of HES RAS Water flowing through systems of open channels ; Computing water surface profiles. Floodplain management ; Flood insurance studies to evaluate floodway encroachments. Additional uses Bridge and culvert design and analysis, Levee studies, Channel modification studies, Dam breach analysis.
- 15. Graphical User Interface(GUI) Data storage/management Graphics, Tabular Output & Reporting GeoRAS – GIS pre and post processor
- 17. Steady flow is the solution of the one-dimensional energy equation. The momentum equation may be used (include hydraulic jumps, hydraulics of bridges, and evaluating profiles at river confluences)where the water surface profile is rapidly varied.
- 19. Unsteady flow is based on solution of 1-D Saint Venant Equation using an finite difference method. It is capable of modelling subcritical, supercritical, and mixed flow regime flow along with the effects of bridges, culverts, weirs, and structures.
- 21. Advantages :- It support by the US Army Corps of Engineers, also acceptance by many government agencies and private firms. It is in the public domain and peer-reviewed, available to download free of charge from HEC's web site. Various private companies are registered as official "vendors" and offer consulting support and add on software. Limitations :- Steep bed slopes (HEC RAS User's manual says >10%); multi-dimensional flow characteristics; complex pipe systems. Large Data Accuracy Required
- 22. The HEC-RAS (4.1) Software New Features: (1) Steady flow water surface profile computations; (2) unsteady flow simulation; (3) Movable boundary sediment transport computations; (4) New RAS mapper floodplain delineation capabilities; (5) Hydrologic routing reaches within an unsteady flow model run; (6) Groundwater leakage for storage areas; (7) Water quality modelling enhancements.