A Two-Stage Framework to Prioritize Monitoring of Authorized River Aggregate Extraction in the Andean Amazon

Abstract River sand and gravel extraction can generate geomorphological and ecological pressure, yet environmental management is often constrained by incomplete information on actual extraction volumes. We developed a two-stage prioritization framework for the Misahuallí River basin in the Ecuadorian Andean Amazon using administrative authorizations issued during 2015–2025. Of 132 records examined, 68 authorizations were located within the basin and 62 were associated with the fluvial system, representing 1,067 ha and a cumulative authorized volume of 8.69 million m³. In the first stage, an Authorized Potential Pressure Index (APPI) integrated total authorized volume, daily authorized volume, authorized daily intensity per unit area, and administrative recurrence. The index was calculated for 52 records with complete information and ranged from 1.00 to 2.85; 22 records (42.3%) were classified as low, 13 (25.0%) as medium, and 17 (32.7%) as high potential pressure. Sensitivity analyses showed high rank concordance under alternative weighting and criterion-exclusion scenarios (Spearman’s ρ = 0.939–0.992). In the second stage, ecosystem services, social uses, field observations, multitemporal imagery, and an exploratory survey of 29 adult stakeholders were used to contextualize monitoring needs without being mathematically incorporated into the index or interpreted as evidence of causal impact. The framework provides a transparent screening approach for targeting administrative verification and environmental monitoring where extraction data are incomplete. Its use for current management requires verification of authorization status and should be complemented with measurements of effective extraction, sediment dynamics, channel change, water quality, and aquatic habitat.