Transcript Load Estimation Tools Workshop
Modeling to Meet Local Watershed Managers’ Needs
Jane Frankenberger Professor and Extension Specialist Agricultural and Biological Engineering Purdue University
Exciting new innovations are extending the capacities of models
Optimization Automated Calibration Interoperability
Are modeling practitioners benefiting from these enhancements?
• • • Are we enabling them to better address their questions?
Are we making it easier for them to use a model?
Are we clarifying model choices and helping ensure quality modeling?
Why focus on local watershed managers?
•
Local watershed
management is the heart of EPA’s nonpoint source control strategy
Watershed management plans funded by EPA Section 319 require load estimates and load
reduction needs
• Local watershed managers need help
Who is a local watershed manager?
• Meet Joe the Watershed Manager • • • • B.S. in Environmental Engineering Works for regional planning agency Proficient in hydrology and water chemistry Samples the water quality at a USGS gage
Modeling needs of a watershed manager
• Answer 3 questions: • watershed? this 20 years What load reduction is needed to ago?
Time • What reductions can we achieve with BMPS we are considering?
What does he need from models?
1. Appropriate model for situation is clear 2. Major processes are represented.
3. Process, inputs, algorithms are transparent 4. Inputs:
Basic inputs require little expertise from user, Additional inputs can be obtained from local data or reasonable defaults, etc.
5. Water monitoring data can be used as a check or improvement.
6. The effect of BMPs can be predicted and compared 7. Accepted best practices; quality of modeling process is known.
Model Selection: Appropriate model for a given situation is reasonably clear to a well-informed user
EPA’s Handbook for Developing Watershed Plans to Restore and Protect our Waters
Model Selection matrix
Model Selection
Characteristics listed
• • • • • • Type “Landscape only” vs “comprehensive”.
Level of complexity. Export functions, Loading functions, Physically-Based Time step. Sub-daily, Daily, Monthly, Annual Hydrology. Surface runoff only, surface and ground water.
Water quality. Sediment, Nutrients, Toxic/pesticides, Metals, User-defined Types of best management practices. BOD, Bacteria, Detention basin, Infiltration practices, Vegetative practices, Wetlands, Other structures
Instead of providing a table of characteristics,
• • • Could we start with needs of a model user, and identifymodels that meet the needs? Could we actually compare what is needed to run each model, and the relative usefulness of results when run by an intelligent, non-expert user? Can we agree on and provide minimum capabilities for a specific purpose?
One characteristic to require: All major processes are represented
“Major” = Responsible for transport of at least x% of the water or pollutants
Evapotranspiration Precipitation Infiltration/plant uptake/ Soil moisture redistribution Surface Runoff Tile Drain Lateral Flow Flow Flow out of watershed Percolation to shallow aquifer Recharge to deep aquifer Return Flow From SWAT manual
Is tile drainage a “major” process/pathway?
Roughly half of the nitrate in Indiana waters is from tile drains …and nitrate is 2/3 of TN
High rates of subsurface drainage are fairly focused geographically
Percent of acres tile drained 0-1% >55% Source: Zachary Sugg, World Resources Institute
Evapotranspiration Precipitation Infiltration/plant uptake/ Soil moisture redistribution Surface Runoff Tile Drain Lateral Flow Flow Percolation to shallow aquifer Streambank Flow out of watershed Recharge to deep aquifer
Is streambank and bed erosion a major process?
Example from Lake Pepin in Minnesota.
(From MN PCA) Slide from MN PCA
• • • • •
To represent the major processes in most watersheds, models need to include:
Surface runoff Tile drainage Groundwater Erosion from fields This eliminates most of the models that practitioners can set up and use in less
3. Process, inputs, algorithms are transparent and peer-reviewed by scientific community
• Example of transparency: SWAT • Executable HTTP Download; FTP Download • Source code HTTP Download; FTP DOwnload
4. Setting up basic inputs (land use, soil, elevation) should require little expertise from user
New opportunity for simplicity: Serving data from web
• • Web Map Service (WMS): serves georeferenced map images generated by a map server using data from a GIS database. Web Feature Service (WFS): serves geographical features, that users can query and spatially analyze. Yes really! The full data come to us
automatically.
SSURGO database
• • • Consistent dataset available nationwide from NRCS Properties of soil map units and each layer Making it available as a web service allows user access without downloading
Most major data stewards provide web feature service access
• • • USGS EPA (HUC boundaries) Many state databases
One example that uses web feature services: WEPP Watershed
Land Use –
NLCD preprocessed for model inputs
Soils: SSURGO queried through web feature service to find map units
Soils:
Map units queried to get properties for each layer
Additional inputs have reasonable, documented default values;
Example: SWAT nitrogen inputs
Variable Definition
SOL_ORGN orgN hum,ly : Initial humic organic nitrogen in soil layer (mg/kg or ppm) CMN RSDCO min : Rate coefficient for mineralization of the humus active organic nutrients rsd : Rate coefficient for mineralization of the residue fresh organic nutrients
How SWAT obtains; Default value
If not specified, SWAT calculates based on organic carbon in the soil layer Default, 0.0003.
Default, 0.05.
RUSLE2 – Rich database of operations and management scenarios
• NRCS employees compiled all likely managements by crop management zones
All inputs documented in a standard way and included when studies or projects are published
Electronic “Supporting Information” (like Environmental Science & Technology) is one good model
5. Clear methods for using water monitoring data in validating or improving results
STEPL
One issue: Calculating load from monitoring data of typical frequency
• LOADEST is a standard, but assumes a relationship between flow and concentration • Not always reasonable: Nitrate loads from tile drainage; seasonal effect overwhelms flow effect.
6. The effect of BMPs can be predicted and compared.
Didn’t we accomplish this 20 years ago?
BMP representation options
• • • BMPs are the heart of the model – RUSLE2 for BMPs related to erosion Physically-based methods for representing BMPs, but model imperfectly suited – Field-scale processes within SWAT BMP pollutant reduction efficiencies used – Many simple models such as STEPL, GWLF – Chesapeake Bay Model (HSPF)
If we don’t accurately represent major process, can’t represent BMPs
• Reduction efficiency methods are only reasonable if if processes are right, and we subtract from the right process • New BMPs for mitigating nitrate from tile drainage cannot be represented in many models Drainage Water Management Bioreactor
7. Quality of modeling process is known;
“Known quality” is goal of monitoring quality assurance program.
Monitoring requires Quality Assurance Project Plan (QAPP) to identify quality of monitoring • • • Example: In Ohio Credible Data Program, water monitoring data is classified into 3 levels: Level 1 – Educate the public and increase awareness Level 2 – Evaluate effectiveness of pollution controls, measure water quality trends Level 3 – Provide level of scientific rigor equivalent to state agency. Can we provide similar levels of quality for modeling projects?
What do we know about the quality of our modeling?
• • • Where good monitoring data are available, we have calibration and validation statistics. But how good is the monitoring?
– Recent papers on monitoring data uncertainty a good step forward Do good statistics translate into useful or “high quality” modeling?
Modeling standards?
• • • The idea of modeling standards was brought up in a session at the ASABE meeting last year.
Groups were formed to work on – Standards for communication of models – Standards for modeling People who are not full-time modelers would benefit from standard method of evaluating model implementation
How will we get there?
1. Recognize that modern software takes enormous numbers of programmer-years.
One post doc can’t develop a model with the quality that is needed.
Cathedral and the Bazaar
6. “Treating your users as co-developers is your least-hassle route to rapid code improvement and effective debugging.” 10. “If you treat your beta-testers as if they're your most valuable resource, they will respond by becoming your most valuable resource.” ideas is recognizing good ideas from your users. Sometimes the latter is better.
The worst of both worlds?
If Microsoft ran like our modeling community … Image: generalsocial.com
How does this help Joe the Watershed Manager?
Let’s look at models of successful collaborative development
• • • • Linux Wikipedia SWAT Others?
• Let’s keep advancing the science, extending capacity of our models….