swcEcon 0.1.0

First CRAN release

New functions (16 exported)

• calc_bcr() – Benefit-cost ratio with discounting, benefit lag, residual value.
• calc_npv() – Net present value with annual cash-flow table.
• calc_irr() – Internal rate of return via bisection (Brent 1973).
• calc_pbp() – Simple and discounted payback period.
• calc_mrr() – Marginal rate of return (CIMMYT 1988).
• calc_mbcr() – Modified benefit-cost ratio (Gittinger 1982).
• calc_soil_loss_cost() – USLE-based soil loss economic valuation.
• calc_nutrient_cost() – NPK replacement cost from erosion.
• calc_water_value() – Groundwater recharge and runoff harvesting value.
• calc_irrigation_benefit() – Additional crop income from SWC-enabled irrigation.
• calc_employment() – Employment generation ratio with MGNREGS norm check.
• sensitivity_analysis() – One-at-a-time sensitivity analysis (8 scenarios).
• calc_switching_value() – Switching value for cost and benefit.
• monte_carlo_swc() – Stochastic BCR/NPV simulation (Pouliquen 1970).
• run_swc_pipeline() – Full appraisal pipeline in one call.
• generate_swc_report() – Self-contained HTML economic appraisal report.

Datasets (6)

• swc_benchmarks – Real: NABARD WDF Reports 2010-2022; PMKSY-WDC (GoI).
• usle_india_soils – Real: NBSS and LUP Technical Bulletin 132 (ICAR).
• rainfall_erosivity_india – Real: IMD + Bhattacharyya et al. (2010).
• swc_cost_norms – Real: PMKSY-WDC Common Guidelines (GoI 2015).
• watershed_projects – Hypothetical: set.seed(2025), 50 projects.
• farmer_adoption – Hypothetical: set.seed(2025), 120 households.

Technical notes

• All source files are pure ASCII – CRAN portable.
• Dataset documentation uses NULL sentinel pattern for roxygen2 compatibility.
• Zero runtime dependencies beyond base R (stats, graphics, grDevices, utils).
• markdown = FALSE in DESCRIPTION – plain Rd syntax throughout.

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