Modeling Phosphorus in the Environment

Modeling Phosphorus in the Environment......Page 1
Preface......Page 3
Editors......Page 4
Acknowledgments......Page 5
Contributors......Page 6
Table of Contents......Page 8
Section I: Basic Approaches......Page 10
Table of Contents......Page 0
1.1 INTRODUCTION......Page 11
1.2 TYPES OF MODELS......Page 12
1.2.2 EXPORT COEFFICIENT MODELS......Page 13
1.3.1 DISSOLVED P......Page 14
1.3.2 PARTICULATE P......Page 16
1.4 FERTILIZER AND MANURE MANAGEMENT......Page 18
1.5 SPATIAL DATA REQUIREMENTS FOR MODELING......Page 19
1.7.1 FLUVIAL PROCESSES......Page 20
1.8 SUMMARY......Page 22
REFERENCES......Page 23
CONTENTS......Page 28
2.2.1 RUNOFF VOLUME......Page 29
2.2.1.1 Curve Number Method......Page 30
2.2.1.2 Curve Number Method Implementation......Page 32
2.2.1.3 Infiltration-Based Approaches......Page 36
2.2.1.3.1 Green and Ampt Approach Description......Page 37
2.2.2 HYDROGRAPH DEVELOPMENT......Page 39
2.2.2.1 Kinematic Flow Routing......Page 40
2.2.2.2 SCS Unit Hydrograph......Page 41
2.2.2.3 Hydrograph Development Implementation......Page 42
2.2.3 STREAMFLOW, OR CHANNEL, ROUTING......Page 43
2.2.3.2 Muskingum Routing Method......Page 44
2.2.3.3 Streamflow, or Channel, Routing Implementation......Page 46
2.2.4.1 Rational Formula......Page 47
2.2.4.3 Peak Runoff Rate Implementation......Page 48
2.3 MODELING EROSION AND SEDIMENT YIELD......Page 51
2.3.1 USLE-BASED APPROACHES......Page 52
2.3.2 USLE-BASED APPROACH IMPLEMENTATION......Page 55
2.3.3 PROCESS-BASED APPROACHES......Page 56
2.3.4 PROCESS-BASED APPROACH IMPLEMENTATION......Page 59
2.3.5 CHANNEL EROSION......Page 60
2.3.6 CHANNEL EROSION IMPLEMENTATION......Page 61
2.4 SUMMARY......Page 63
REFERENCES......Page 67
CONTENTS......Page 72
3.1.1.1 Model Based on Laboratory-Derived Relationships......Page 73
3.1.1.2 Model Based on Field-Derived Relationships......Page 76
3.1.2.1 Model Based on Laboratory-Derived Relationships......Page 80
3.2 MODELING PARTICULATE INORGANIC P IN SURFACE RUNOFF......Page 82
REFERENCES......Page 84
4.1 INTRODUCTION......Page 87
4.3.1.1 Vertical Flow......Page 89
4.3.1.2 Nonequilibrium and Preferential Flow......Page 92
4.3.1.3 Lateral Flow......Page 95
4.3.2.1 Inorganic P Leaching......Page 96
4.3.2.3 Preferential and Subsurface Particulate P Transport......Page 102
4.4 MODEL EVALUATION......Page 103
4.5 CONCLUSIONS......Page 104
REFERENCES......Page 105
5.1 INTRODUCTION......Page 110
5.2 ABIOTIC AND BIOTIC PROCESSES......Page 111
5.3.1 DETERMINING PHOSPHORUS SPIRALING......Page 114
5.3.2 STREAM PROPERTIES AND PHOSPHORUS SPIRALING......Page 118
5.4 ALGAL AND MICROBIAL PROCESSES......Page 119
5.5.1 SEDIMENT SOURCE EFFECTS......Page 120
5.5.2 SEDIMENT AND EQUILIBRIUM PHOSPHORUS CONCENTRATIONS......Page 122
5.6 IMPACT OF STREAM PROCESSES ON EUTROPHICATION......Page 125
5.7 MODELING PHOSPHORUS TRANSPORT IN STREAM CHANNELS......Page 127
5.8 CONCLUSIONS......Page 129
REFERENCES......Page 130
CONTENTS......Page 136
6.1 SOURCES OF UNCERTAINTY IN MODELING P TRANSPORT TO STREAM CHANNELS......Page 137
6.2 SOURCES OF UNCERTAINTY......Page 138
6.3 UNCERTAINTY IS NOT ONLY STATISTICS......Page 139
6.4 UNCERTAINTY ESTIMATION: FORMAL BAYES METHODS......Page 140
6.5 UNCERTAINTY ESTIMATION BASED ON THE EQUIFINALITY CONCEPT AND FORMAL REJECTIONIST METHODS......Page 142
6.6 UNCERTAINTY AS PART OF A LEARNING PROCESS......Page 145
6.7.1 THE MACRO MODEL......Page 147
6.7.2.1 Drainage Discharge and Phosphorous Concentrations......Page 148
6.7.3 MACRO IMPLEMENTATION WITHIN A MODEL REJECTION FRAMEWORK......Page 149
6.7.4.1 Using Initial Rejection Criteria......Page 151
6.7.4.3 Simulations for the Period from 1994 to 1995......Page 153
6.7.4.4 Simulations and Parameterizations for the Period 1995 to 1996......Page 155
6.8 LEARNING FROM REJECTION: WHAT IF ALL THE MODELS TRIED ARE NONBEHAVIORAL?......Page 158
6.9 WHAT ARE THE IMPLICATIONS FOR P MODELS?......Page 160
REFERENCES......Page 162
Section II: Models......Page 166
CONTENTS......Page 167
7.1 SWAT MODEL BACKGROUND......Page 168
7.2 PHOSPHORUS MODELING IN SWAT: SOIL PHOSPHORUS INTERACTIONS......Page 171
7.2.1 INITIALIZATION OF SOIL PHOSPHORUS LEVELS......Page 172
7.2.2 MINERALIZATION, DECOMPOSITION, AND IMMOBILIZATION......Page 174
7.2.3 INORGANIC PHOSPHORUS SORPTION......Page 175
7.2.5 FERTILIZER APPLICATION......Page 177
7.2.6 PHOSPHORUS UPTAKE BY PLANTS......Page 178
7.3.2 ORGANIC AND MINERAL PHOSPHORUS ATTACHED TO SEDIMENT IN SURFACE RUNOFF......Page 179
7.4 IN-STREAM PHOSPHORUS CYCLE......Page 180
7.5 VERSIONS OF SWAT......Page 181
7.6 SWAT MODEL APPLICATIONS......Page 183
7.7 MODEL LIMITATIONS......Page 186
7.8 SWAT MODIFICATIONS......Page 187
7.9 CONCLUSIONS......Page 188
REFERENCES......Page 189
8.1 BRIEF HISTORY OF MODEL DEVELOPMENT......Page 192
8.2 MODELING OF HYDROLOGY......Page 193
8.3 MODELING OF PHOSPHORUS......Page 198
8.4 MODELING OF SEDIMENT......Page 202
8.5 CALIBRATION......Page 205
8.6 CASE STUDY: UPPER ETOWAH RIVER WATERSHED......Page 206
8.7 COMPARING HSPF AND SWAT......Page 213
8.8 CONCLUSIONS......Page 214
REFERENCES......Page 215
CONTENTS......Page 218
9.2 WATERSHED PROCESSES CONSIDERED IN AnnAGNPS......Page 219
9.3 MODEL INPUTS AND OUTPUTS......Page 220
9.4 AnnAGNPS MODEL OF PHOSPHORUS PROCESSES......Page 222
9.4.1 SOIL INITIAL PHOSPHORUS CONTENT......Page 223
9.4.2 ORGANIC P SIMULATION PROCESSES......Page 224
9.4.3.1 Calculation of Inorganic P Additions to a Cell......Page 225
9.4.3.2 Calculation of Intermediate Inorganic P Mass Balance......Page 226
9.4.3.3.1 Loss through Surface Runoff......Page 227
9.4.3.3.3 Loss through Plant Uptake of Inorganic P......Page 228
9.5.1 STUDY WATERSHED AND MONITORING INFORMATION......Page 229
9.5.2 INPUT DATA PREPARATION......Page 230
9.5.3 SENSITIVITY ANALYSIS......Page 232
9.5.4 MODEL CALIBRATION AND VALIDATION......Page 235
REFERENCES......Page 241
10.1 INTRODUCTION......Page 244
10.2.2 WATER CYCLE......Page 245
10.2.3 SEDIMENT DETACHMENT AND TRANSPORT......Page 250
10.2.4 PHOSPHORUS TRANSFORMATIONS AND LOSSES......Page 251
10.3 VALIDATION AND APPLICATIONS......Page 255
10.5 CONCLUSIONS......Page 260
REFERENCES......Page 261
11.1 INTRODUCTION......Page 263
11.2 HISTORY AND DEVELOPMENT......Page 264
11.4 THE MODELING FRAMEWORK......Page 265
11.5 PHOSPHORUS PROCESSES......Page 270
11.6 CASE STUDIES......Page 271
REFERENCES......Page 277
12.1 HISTORY OF MODEL DEVELOPMENT......Page 279
12.3 PREDICTING INFILTRATION AND RUNOFF......Page 281
12.4 PREDICTING PHOSPHORUS IN RUNOFF......Page 286
12.6 SIMULATING MANAGEMENT AND BMPS......Page 287
12.7 SIMULATING IN-STREAM PROCESSES......Page 288
12.8.1 USE OF GWLF TO EVALUATE BMPS......Page 289
12.8.2 ACCURACY OF GWLF: COMPARISON OF SIMULATED TO MEASURED LOADS......Page 291
12.8.3 SIMULATION OF RUNOFF VOLUMES AND SOURCE AREAS......Page 294
12.10 AVAILABILITY OF MODEL......Page 297
REFERENCES......Page 298
Section III: Phosphorus Indices, Best Management Practices, and Calibration Data......Page 300
13.1.1 BACKGROUND......Page 301
13.1.2 DEVELOPMENT......Page 304
13.2.1 PARAMETERS......Page 306
13.2.2 CALCULATING A PHOSPHORUS INDEX VALUE......Page 322
13.3.1 EXAMPLES OF INDEX SITE ASSESSMENT AND INTERPRETATION......Page 323
13.4 INTEGRATION OF P INDICES INTO EXISTING MODELS OR NUTRIENT MANAGEMENT PLANNING SOFTWARE......Page 325
13.5 FIELD TESTING......Page 326
13.7 CONCLUSIONS......Page 327
REFERENCES......Page 328
CONTENTS......Page 333
14.2.1 OVERVIEW......Page 334
14.2.2 INCONSISTENCIES BETWEEN PRESCREENING TOOLS AND PIS......Page 335
14.2.4 LACK OF SLIDING SCALES IN OVERALL PI INTERPRETATIONS......Page 336
14.2.5 THE CHICKEN–EGG PROBLEM......Page 337
14.2.6 THE BERMUDA TRIANGLE......Page 339
14.2.7 TEMPORAL DISCONTINUITIES......Page 340
14.3.2 SOME INPUT DATA MAY NOT BE KNOWN DURING PLANNING......Page 341
14.3.4 GAMING THE SYSTEM......Page 342
14.4.1 POTENTIAL IMPLEMENTATION APPROACHES......Page 343
14.4.2.1 Interpreting the Risk Assessment Procedure......Page 345
14.4.2.3 Errors or Gaps in Soils Data......Page 346
14.4.2.4 Program Support and Maintenance......Page 347
14.5 CONCLUSIONS......Page 348
REFERENCES......Page 349
CONTENTS......Page 350
15.1 INTRODUCTION......Page 351
15.2.1 READILY MODELED......Page 353
15.2.3 SPECIALIZED MODELS......Page 356
15.2.4 CAVEATS......Page 357
15.2.5 MODEL COMPARISONS......Page 358
15.3.1 DEVELOPING A BMP TOOL......Page 359
15.3.2 EXAMPLE BMP TOOL APPLICATION......Page 361
15.4 COST CONSIDERATIONS OF BMP RECOMMENDATIONS......Page 362
15.5 COMBINING POLLUTION REDUCTION AND COST......Page 364
15.5.1 OPTIMIZING BMP SELECTION AND PLACEMENT......Page 365
15.5.3 THE GENETIC ALGORITHM......Page 366
15.5.4 CURRENT CHALLENGES IN OPTIMIZATION......Page 368
15.6 APPLICATIONS......Page 369
15.6.1 FARM-LEVEL EVALUATION, SUBDIVIDED BY HRUS (TBW)......Page 370
15.6.2 WATERSHED-LEVEL EVALUATION, SUBDIVIDED BY HRUS (TBW)......Page 371
15.7 SUMMARY......Page 374
REFERENCES......Page 375
16.1 INTRODUCTION......Page 381
16.2 PROJECT DESIGN FACTORS......Page 382
16.2.1 MONITORING RESOURCES......Page 383
16.2.2 FLOW CHARACTERIZATION......Page 384
16.2.3.1 Base Flow and Low Flow......Page 386
16.2.3.2 Storm Flow......Page 387
16.2.4 AUTOMATED STORM SAMPLING SETTINGS......Page 388
16.2.4.2 Sampling Interval......Page 389
16.2.5 ALTERNATIVE PROCEDURES (REGRESSION METHODS)......Page 393
16.3 UNCERTAINTY IN P TRANSPORT MEASUREMENT......Page 394
16.4 SUMMARY......Page 396
REFERENCES......Page 397
Section IV: Modeling in the Future......Page 400
17.1 INTRODUCTION......Page 401
17.3 SOIL PHOSPHORUS POOLS AND MODEL PARAMETERS......Page 402
17.4 LEACHING OF PHOSPHORUS......Page 404
17.5 BEST MANAGEMENT PRACTICES......Page 405
17.6 IN-STREAM PROCESSES......Page 406
17.8 CALIBRATION AND UNCERTAINTY......Page 407
17.9 DATA TO SUPPORT PHOSPHORUS MODELING......Page 408
REFERENCES......Page 409