# Presentation: 053483

## Introduction to the Water Quality Analysis Modeling System

- WASP
- Version 7.0
- April, 2005

## US EPA Disclaimer

- Although this work was reviewed by EPA and approved for presentation, it may not necessarily reflect official Agency policy.
- Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

## Course Objectives

- Modeling Principles
- Modeling Theory
- Processes in WASP
- Limitations of process descriptions
- Modeling Practice
- Using  the WASP Interface
- Using WASP for real-world problems
- Case Study Applications of WASP
- Discussion of Data Needs

## Basic Principle of Mechanistic Models

- Laws of Conservation
- Conservative properties are those that are not gained or lost through ordinary reactions.  Therefore we can account for any change by simply keeping track of all those processes that can cause change
- Examples of conservative properties
- Mass (water mass, constituent mass)
- Momentum
- Heat

## Three Dimensional Transport Equation

## Box Model Approach

- Numerical solution allows greater flexibility as to processes considered (i.e. eutrophication, toxics, etc.)
- Allows greater flexibility as to segmentation
- Flows and mixing coefficients are obtained from
- Field data
- Hydrodynamic models (which produce output that can be read by WASP)

## Box Modeling Approach

- Boxes
- The boxes have no defined shape, so can be fit to any morphometry
- The boxes can be “stacked” so the approach can be applied to 0 dimensions (1 box) or 1, 2 or three dimensional systems

## Slide 8

## WASP7 Water Quality Modules

- Eutrophication (eutro.dll)
- DO, BOD, nutrients, phytoplankton, periphyton
- Simple Toxicant (toxi.dll)
- Partitioning and first order decay
- Simple metal or organic chemical, solids
- Non-Ionic Organic Toxicants (toxi.dll)
- Detailed fate processes, reaction products, solids
- Organic Toxicants (toxi.dll)
- Detailed fate processes, ionization, reaction products, solids
- Mercury (mercury.dll), slightly altered from toxi.dll
- Hg0, HgII, MeHg, solids
- HEAT (heat.dll)
- full/equilibrium heat balance + pathogens

## WASP Structure

- WASP
- Transport
- Bookkeeping

- Kinetics

- Organic Chemical Model
- Eutrophication Model
- Mercury Model

## WASP Terminology

- Segments

## WASP Systems: Conventional Water Quality Modules

**EUTRO**
- Dissolved oxygen
- CBOD (three forms)
- Phytoplankton
- Periphyton
- Detritus (C, N, P)
- Dissolved organic nitrogen
- Ammonia/ammonium
- Nitrate
- Dissolved organic phosphorus
- Orthophosphate
- Salinity
- Solids
- Sediment Diagenesis

**HEAT**
- Temperature
- Salinity
- Coliform
- Conservative 1 and 2

## WASP Systems: Toxicant Modules

**Simple Toxicant**
- Chemical
- Silts/Fines
- Sands
- Biotic solids
**Organic Toxicants (both non-ionizing and ionizing)**
- Chemical 1
- Chemical 2
- Chemical 3
- Silts/Fines
- Sands
- Biotic solids

**Mercury**
- Elemental, Hg0
- Divalent, HgII
- Methyl, MeHg
- Silts/Fines
- Sands
- Biotic solids

## Potential WASP Time Scales

- Steady
- Seasonal
- Monthly
- Daily/Hourly

## WASP Advantages and Features

- Network Flexibility
- Applicable to most water body types at some level of complexity
- Most Water Quality Problems
- Conventional Water Quality: DO, eutrophication, heat
- Toxicant Fate: organics, simple metals, mercury
- Separation of Processes
- Transport
- Kinetics
- External Links to Models and Spreadsheets
- Two Solution Techniques
- Simple/Quick – Euler
- Complex/Flux Limiting -- COSMIC

## WASP External Linkages

_**Loading Models**_
**SWMM**
**HSPF**
**LSPC**
**NPSM**
**PRZM**
**GBMM**

_**Hydrodynamic**_
_** **__**Models**_
**EFDC**
**DYNHYD**
**EPD-RIV1**
**SWMM**

_**Bioaccumulation**_
**BASS**
**FCM-2**

_**External **_
**Spreadsheets**
**ASCII Files**
**Windows **
**Clipboard**

## WASP Limitations

- Does not handle some variables and processes:
- Mixing zone processes
- Non aqueous phase liquids (e.g., oil spills)
- Segment drying (mudflats, flood plains)
- Metals speciation reactions (special module, META4, not part of general WASP release)
- Potentially large external hydrodynamic files
- Separate eutrophication and toxicant fate modules
- Cannot readily be run in batch mode
- Automatic calibration programs
- Monte Carlo programs

## WASP is a Variable Complexity Modeling System

- When building a water body model, adjust complexity to match the problem.
- More Complex Aquatic Systems
- More Complex Chemical Behavior
- More Complex Management Questions

## Development of Complexity in Water Quality ModelingApplications

## Iterative Model Development Process

## How Complex Should Final Computational Model Be?

- Proper model complexity is driven by:
- The complexity of the environmental system.
- The complexity of the pollutants of concern.
- The management questions and related need for accuracy.
- Consequences for overly simple model:
- Miss key processes and extrapolate inaccurately.
- May not address relevant management questions.
- May not be defensible to adversarial review.
- Insufficiently adaptable to changing management requirements.
- Consequences for overly complex model:
- Adds unnecessary data collection and computational burdens.
- Adds to uncertainty.
- Shifts focus away from problem solutions to endless analysis.

## Management-Related Questions Requiring More Complex Models

- What are the spatial and temporal distributions of target pollutants (particularly in mixed-media environments) under various management scenarios?
- What are the relative contributions of various sources of pollutants over time?
- What are the likely pollutant attenuation trajectories and times to recovery under various management scenarios?
- What are the relative effects of transient or extreme events, such as spills or storms?
- What are the possible effects of poorly understood environmental events?

## Goal of Model Complexity