Hung-Cuong PhamDepartment of Chemical Engineeringhungcuongknu@yahoo.com

ARCGIS Desktop, EPANET and Watershed

ARCGIS Desktop

History of ESRI Products

• ARC/INFO developed – 1980s*– Couples INFO database with graphical tools for

display and analysis– Data structures

• Coverages– Point– Arc/Line– Polygon

Brief History of ESRI Products• ArcView 1.0 – early 1990s

– Very limited functionality– Display only– Buggy – crashes often

• ARC/INFO continues to be enhanced by adding new commands– ARCTOOLS graphical interface attempts to

make things simpler

Brief History of ESRI Products• ARCView versions 2 and 3 – mid to late 1990s

– Greatly expanded capabilities• Data editing and analysis

– AVENUE programming language allows extensions to be added to ARCVIEW

– Data Structures• Shape Files (editable)• Coverages (display only)• Images• Grids (with extensions)

Brief History of ESRI Products• ArcGIS Desktop – 1999- present

– Subsumes both ARC/INFO and ArcView– Restricted to Windows NT-family operating

system– Arcview is a limited version of ARCGIS Desktop– Data Structures

• Shape Files • Geodatabases

– Script/Programming Language: Visual Basic

ArcGIS Components

• ArcCatalog– Manage data

• ArcMap– Create maps– Analysis

• ArcToolbox– Stand-alone Analysis and Conversion

• ArcScene– 3-D display

ARGIS Components

• ARCMAP

ArcMap

• ArcMap is designed to help you create publication-quality maps

• It extends the display capabilities of ArcView 3 but uses an entirely new interface– Everything is there, but you will need to work to

locate it

Description

EPANET models:

Flow of water in pipes,

Pressure at junctions,

Height of water in tanks,

Concentration of a chemical,

Water age, and

Source tracing ( trace the source of a contaminant

Applications:

Plan and improve a system’s hydraulic performance Pipe, pump and valve placement and sizing Energy minimization Fire flow analysis Vulnerability studies for security planning Operator training Maintain and improve the quality of water delivered to consumers Design

sampling programs Study disinfectant loss and by-product formation Evaluate alternative strategies for improving water quality such as:• Altering source utilization within multi-source systems,• Modifying pumping and tank filling/emptying schedules to reduce water age,• Utilizing booster disinfection stations at key locations to maintain target

residuals, and • Planning a cost-effective program of targeted pipe cleaning and replacement.

Schematic of Chemical and Microbiological Transformations at the Pipe Wall

Schematic of Chemical and Microbiological Transformations in Drinking Water

Water Quality Modeling Principles

Conservation of mass within differential lengths of pipe

Complete and instantaneous mixing of the water enteringpipe junctions

Appropriate kinetic expressions for the growth or decay of thesubstance as it flows through pipes and storage facilities

This change in concentration can be expressed by a differentialequation of the form:

This change in concentration can be expressed by a differentialequation of the form:

Where: – Cji is the substance concentration mass/ft3) at position x and time t in the link between nodes i and j

– vij is the flow velocity in the link (equal to the link’s flow divided by its cross-sectional area in ft/sec

– kij is the rate at which the substance reacts within the link (mass/ft3/sec)

Storage tanks can be modeled as completely mixed,variable volume reactors where the change in volumeand concentration over time are:

Where:- Vs is the volume (ft3) of the tank- Cs is the concentration in tank s

The following equation represents the concentration of material leaving the junction and entering a pipe:

Standard Toolbar

Map Toolbar

EPANET INPUT

JunctionsCoordinates (can import from GIS)ElevationDemand (gallons per minute) Initial quality

EPANET INPUT

Pipes

Length

Diameter

Roughness coefficient ( Hazen-Williams C

factor)

EPANET INPUT

Tanks data

Coordinates ( can import from GIS)

Elevation

Levels

Initial

Minimum

Maximum

Diameter

Volume

EPANET INPUT

Pumps Data

Start node

End node

Pump curve

Initial status

(open, close)

EPANET OUTPUT

Junctions (nodes)

Pressure

Quality (e.g., residual chlorine concentration)

Pipes (links)

Flow (gallons per minute)

Velocity (ft per second)

Head loss (ft)

Tanks: inflow, level, quality

Pump: flow rate

Overview Hydrology Effect of urbanization Stability concepts Modeling

- Hydrologic- Hydraulic- Examples

Hydrology: the distribution and movement of water.

WatershedAn area contributing runoff and sediment.

Factors That Affect Discharge

Precipitation Antecedent

moisture Snow melt Frozen ground Spatial extent of

storm

Ease of runoff movement (time of concentration)

Watershed size (delineation)

Soils Land use

Human activity can alter these.

Ease of Water Movement Time of concentration is the time for runoff to travel from the hydraulically most distant

point of the watershed. Channelization, addition of drains, storm sewers, pavement, graded lawns, and bare soils

convey water more rapidly.

The altered flow regime affects: habitat (water velocity, temperature, sediment,

other pollutants)

The altered flow regime affects: habitat (water velocity, temperature, sediment,

other pollutants) flooding (frequency and elevation)

This is an active down-cut. Stability cannot be determined from one photo however.

Stream Instability causes excessive erosion at many locations throughout a stream reach.

Modeling Software HEC-HMS (Hydrologic Modeling System), HEC-1: combines

and routes discharges from multiple subbasins HEC-RAS (River Analysis System), HEC-2: One-dimensional

steady flow water surface profile computations. TR-55: calculates urban runoff, intended for smaller watersheds of

two to three reaches. TR-20: similar to TR-55 but for intended for whole basin. SWMM (StormWater Management Model): single event and

continuous simulations of water quantity and quality, primarily for urban areas.

Numerous others

Storm Water Management Model (SWMM)

The EPA Storm Water Management Model (SWMM) is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment areas on which rain falls and runoff is generated. The routing portion of SWMM transports this runoff through a conveyance system of pipes, channels, storage/treatment devices, pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period comprised of multiple time steps.

SWMM was first developed back in 1971 and has undergone several major upgrades since then. The current edition, Version 5, is a complete re-write of the previous release. Running under Windows, EPA SWMM 5 provides an integrated environment for editing drainage area input data, running hydraulic and water quality simulations, and viewing the results in a variety of formats. These include color-coded drainage area maps, time series graphs and tables, profile plots, and statistical frequency analyses.

This latest re-write of EPA SWMM was produced by the Water Supply and Water Resources Division of the U.S. Environmental Protection Agency's National Risk Management Research Laboratory with assistance from the consulting firm of CDM, Inc.

http://www.epa.gov/athens/wwqtsc/html/swmm.html

Water Quality Models

Water quality models simulate the fate of pollutants and the state of selected water quality variables in water bodies. They incorporate a variety of physical, chemical, and biological processes that control the transport and transformation of these variables. Water quality models are driven by hydrodynamics, point and nonpoint source loadings, and key environmental forcing functions, such as temperature, solar radiation, wind speed, pH, and light attenuation coefficients. The external drivers may be specified from observed data bases, or simulated using specialized models describing, for example, the water body hydrodynamics or the watershed pollutant loading. The internal forcing functions may also be specified from databases, or calculated within the water quality model using a range of empirical to mechanistic process formulations. Examples include temperature, pH, and light attenuation.Some water quality models focus on particular problem contexts, such as dissolved oxygen depletion or organic chemical fate. Other models are more general, and can be used to simulate different water quality problems. Similarly, some water quality models specialize in particular water body types, such as lakes or streams. Others are more general, and can be applied to several types of water bodies. Each water quality model has its own set of characteristics and requirements. The reader should thoroughly review the documentation and consider its strengths, limitations, and data requirements prior to application.

http://www.epa.gov/athens/wwqtsc/html/swmm.html