The Feasibility Surface: Mapping the Landscape of Run-of-River Hydropower Potential

Assessing run-of-river small hydropower (SHP) potential requires balancing conflicting technical, economic, and socio-environmental criteria. Traditional assessment frameworks rely on discrete point-based site inventories, which often overlook regional landscape constraints and project overlap. To overcome this limitation, this study introduces the concept of a Feasibility Surface (FS), a novel, continuous spatial landscape that maps overall development viability across an entire drainage basin. Operating within a Geographic Information System (GIS), we integrated the Analytic Hierarchy Process (AHP) to systematically weight nine multi-dimensional variables across Economic, Ecological, and Social criteria. Input layers were max-normalized using criterion-specific rules and aggregated through a weighted linear combination to generate a continuous Feasibility Index (FI). Applied to the Huazuntlán River basin in Mexico, the resulting continuous surface successfully delineates optimal development corridors, moving beyond fixed-point targets. Local one-at-a-time sensitivity analyses confirmed that these spatial clusters are physically robust and highly stable under weight variations. Furthermore, an exhaustive combinatorial search was executed over the continuous surface to extract optimal, non-overlapping multi-plant portfolios that avoid hydraulic interference. Mathematically and practically, this continuous feasibility landscape provides a valuable macro-screening tool for sustainable water resource planning. It allows environmental managers and energy developers to prioritize alternative exploitation corridors, balance localized ecological constraints, and optimize distributed renewable energy portfolios without compromising basin-scale ecological integrity.