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Nature-based Solutions (NbS) and other small-scale, decentralized infrastructure elements are increasingly recognized for their potential to reduce flood and drought impacts. Systematic evaluation approaches are now needed to identify effective spatial configurations and temporal staging for the implementation of NbS. This study develops and applies a hydrologic modeling framework to evaluate five NbS pathways combining alien invasive vegetation removal and replacement by indigenous grasslands or forest, and targeted soil conductivity modification to enhance infiltration. Pathways were assessed using multi-criteria metrics including hydrologic performance, feasibility, cost, and co-benefits for enhancing dry season flows. The five adaptation pathways were developed as representative combinations of short-, mid-, and long-term NbS interventions selected based on modeled hydrologic performance, feasibility, and stakeholder-identified implementation priorities and constraints. Pathway 1 and Pathway 2 emphasize the alien invasive vegetation removal and replacement with indigenous grasslands in different spatial sequences; Pathway 3 combines the alien invasive vegetation replacement with grasslands and soil modification; Pathway 4 combines the alien invasive vegetation replacement with grasslands and indigenous forest in different locations; and Pathway 5 combines the alien invasive vegetation replacement with indigenous grasslands and forest with soil modification at high-performing locations. Results show that each of the five adaptation pathways improves water availability relative to the baseline, with variations in their performance, feasibility, cost, and co-benefits. Across pathways, modeled average daily flow at the outlet increased from 6.0 m 3 /s (baseline) to 6.8–7.4 m 3 /s (+0.8–1.4 m 3 /s; ∼13–23%) under full-year conditions. Improvements were more pronounced during water-stressed periods: dry-season flow increased from 3.2 m 3 /s to 3.8–4.0 m 3 /s (∼19–25%), and flow in the driest year increased from 0.6 m 3 /s to 1.0–2.9. Pathway 5 enhanced the dry season flows the most while mitigating peak flows and providing ecosystem benefits. This research advances the integration of hydrologic modeling of decentralized land use changes and water system infrastructure elements with stakeholder-driven decision-making, thereby contributing to the adaptation planning and Adaptative Pathways Planning literature.
Mandavya et al. (2026) studied this question.