User Requirements Specification (URS)
| Document Version: 1.0 | Date: October 30, 2025 |
This page provides an overview. View the full URS document on GitHub.
Purpose
This User Requirements Specification defines the user requirements for the Casanova Drift Model (CDM), a mathematical model designed to simulate pesticide spray drift during agricultural applications.
Intended Users
- Agricultural researchers
- Regulatory scientists
- Environmental risk assessors
- Pesticide application specialists
- Software developers integrating drift modeling capabilities
Functional Requirements Summary
Input Requirements
| ID | Requirement | Description |
|---|---|---|
| FR-1.1 | Droplet Size Distribution | Pairs of droplet diameter (μm) and cumulative volume fraction |
| FR-1.2 | Atmospheric Properties | Dry air temperature, barometric pressure, relative humidity |
| FR-1.3 | Wind Velocity Profile | Wind velocity measurements at specified elevations |
| FR-1.4 | Application Parameters | Nozzle height, canopy height, pressure, angle, application rate |
| FR-1.5 | Field Geometry | Downwind depth, crosswind width, nozzle spacing |
| FR-1.6 | Solution Properties | Water density, dissolved solids density, mass fraction |
Processing Requirements
| ID | Requirement | Description |
|---|---|---|
| FR-2.1 | Atmospheric Property Calculations | Wet air density, dynamic viscosity, dew point, wet bulb temperature |
| FR-2.2 | Wind Profile Characterization | Friction height (z₀), friction velocity (Uf) |
| FR-2.3 | Droplet Transport Simulation | ODE integration for Z, X, Vz, Vx, Mw, Vvwx |
| FR-2.4 | Droplet Size Distribution Processing | Curve fitting or finite difference approximation |
| FR-2.5 | Deposition Calculation | On-field and off-field deposition as %IAR |
Output Requirements
| ID | Requirement | Description |
|---|---|---|
| FR-3.1 | Deposition Output | Distance–deposition pairs (%IAR) |
| FR-3.2 | Summary Report | Input parameters, derived properties, statistics |
| FR-3.3 | JSON Output | Machine-readable results in JSON format |
Integration Requirements
| ID | Requirement | Description |
|---|---|---|
| FR-4.1 | C API | C-compatible shared library API |
| FR-4.2 | CLI | Command-line executable with JSON I/O |
| FR-4.3 | R Package | R wrapper for model execution |
Non-Functional Requirements Summary
- Performance: Typical model run completes within 60 seconds; memory usage under 1 GB
- Numerical Accuracy: Relative tolerance 1×10⁻⁴; component-specific absolute tolerances
- Platform Support: Windows (x64), Linux (x64), macOS (x64, ARM64)
- Compiler Support: C++17 with MSVC, GCC, and Clang
- Error Handling: Clear error messages with customizable error handler
Validation Requirements
The system is validated against SETAC DRAW test cases:
| Case | Trial ID | Nozzle Type | Nozzle Pressure | Surfactant |
|---|---|---|---|---|
| B | FR_1_017 | AXI 11002 | 250 kPa | None |
| G | NL_1_660 | XR 11004 | 300 kPa | Agral |
| I | DE_4_006 | XR 11004 | 250 kPa | None |