1. CE5504 – Surface Water Quality Modeling CE5504 Surface Water Quality Modeling General Lecture 2. Model Development

2. Empirical Models CE5504 – Surface Water Quality Modeling Secchi disk and chlorophyll (Chapra 1997, Figure 29.6)

3. Empirical Models CE5504 – Surface Water Quality Modeling Vollenwieder plot (Chapra 1997, Figure 29.1)

4. (Chapra 1997, Figure 29.4) Linked Empirical-Mechanistic Models CE5504 – Surface Water Quality Modeling

5. Mechanistic Mass Balance Models CE5504 – Surface Water Quality Modeling (Chapra 1997, Figure 1.5)

6. (Chapra 1997, Figure 18.8) Temporal Resolution CE5504 – Surface Water Quality Modeling

7. Spatial Resolution CE5504 – Surface Water Quality Modeling (Chapra 1997, Figure 16.1)

8. Time and Space Scale of Water Quality Problems CE5504 – Surface Water Quality Modeling (Chapra 1997, Figure 18.9)

9. Kinetic Resolution CE5504 – Surface Water Quality Modeling Total Phosphorus Available Particulate Phosphorus Refractory Particulate Phosphorus Dissolved Organic Phosphorus Soluble Reactive Phosphorus

10. Things should be made as simple as possible -- but no simpler. Albert Einstein image source: www.physik.uni-frankfurt.de/~jr/physpiceinstein.htmlwww.physik.uni-frankfurt.de/~jr/physpiceinstein.html The Guiding Principle

11. unlimited cost cost cost +  $ desired reliability Model Complexity Model Reliability Defensible, Credible, Cost-Effective

12. Model Complexity Screening  Management  Research Striking a Balance

13. 1925-1960 (Streeter-Phelps) Problems: untreated and primary effluent Pollutants: BOD Systems: streams and estuaries (1D) Kinetics: linear, feed forward Solutions: analytical Modeling: Historical Development CE5504 – Surface Water Quality Modeling (Chapra 1997)

14. 1960-1970 (Computerization) Problems: primary and secondary effluent Pollutants: BOD Systems: streams and estuaries (1D/2D) Kinetics: linear, feed forward Solutions: analytical and numerical Modeling: Historical Development CE5504 – Surface Water Quality Modeling (Chapra 1997)

15. 1970-1977 (Biology) Problems: eutrophication Pollutants: nutrients Systems: streams, lakes and estuaries (1D/2D/3D) Kinetics: nonlinear, feedback Solutions: numerical Modeling: Historical Development CE5504 – Surface Water Quality Modeling (Chapra 1997)

16. 1977- 2000 (Toxics) Problems: toxics Pollutants: organics, metals Systems: sediment-water interactions food chain interations, streams, lakes and estuaries Kinetics: linear, feed forward Solutions: analytical Modeling: Historical Development CE5504 – Surface Water Quality Modeling (Chapra 1997)

17. 2000 - present (Ecosytems) Problems: ecosystem change, climate, invasives Pollutants: natural components – carbon, nutrients, organisms Systems: primary production, food web interactions Kinetics: nonlinear, feedback Solutions: numerical Modeling: Historical Development CE5504 – Surface Water Quality Modeling (Chapra 1997) Benthic Invertebrates Phytoplankton Whitefish