NEWS

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swcEcon 0.1.0 (2026-04-16)

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.