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Seminar on Hydrological modelling

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Seminar on Hydrological modelling

  1. 1. Prepared By: VISHVAM PANCHOLI (130280712013) ME-Water Resources & Management L.D.College of Engineering,Ahmedabad-380061
  2. 2. Outline of seminar *Basic Concept of modelling *Introduction of modelling *Introduction to HEC RAS Model *Overview of HEC RAS Model
  3. 3. What is Hydrological modelling
  4. 4. Hydrologic models are simplified, conceptual representations of the Hydrologic cycle. Source:- U.S.D.S
  5. 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. 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
  7. 7. Hydrological Modelling Black Box Conceptual Deterministic Lumped Semi- Distributed Distibuted
  8. 8. 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).
  9. 9. 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.
  10. 10. Introduction to HEC RAS
  11. 11. 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.
  12. 12. 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
  13. 13. 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.
  14. 14. Graphical User Interface(GUI) Data storage/management Graphics, Tabular Output & Reporting GeoRAS – GIS pre and post processor
  15. 15. 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.
  16. 16. 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.
  17. 17. 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
  18. 18. 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.
  19. 19. * http://www.hec.usace.army.mil http://csdms.colorado.edu/wiki/Hydrological_Models http://en.wikipedia.org/wiki/HEC-RAS http://www.forrex.org http://www.eng.uwo.ca/research http://www.fema.gov

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