Evaluación del Índice de Calidad del Agua de Riego (IWQI) en los principales ríos de la provincia del Carchi, Ecuador para el periodo enero-junio 2025.

Abstract

This study assessed the irrigation water quality of the main rivers in the province of Carchi (Ecuador) from January to June 2025, using the Irrigation Water Quality Index (IWQI). Seven sampling points were selected upstream of agricultural water intake sites. Physicochemical parameters analyzed included TDS (5–310 mg/L), electrical conductivity EC (0.04–0.15 dS/m), pH (7.25–7.63), Ca²⁺ (0.28–1.53 meq/L), Mg²⁺ (0.27– 1.51 meq/L), Na⁺ (0–4.35 meq/L), K⁺ (0.15–1.28 meq/L), HCO₃⁻ (0.33–1.88 meq/L), Cl⁻ (≤ 0.00055 meq/L), SO₄²⁻ (2.15–6.81 meq/L), and BOD₅ (19–73 mg/L). From these results, the following indicators were calculated: Sodium Adsorption Ratio (SAR: max. 8.87 at M5), Sodium Percentage (%Na: max. 82.89% at M5, exceeding FAO thresholds), Magnesium Adsorption Ratio (49.66–49.71%), Residual Sodium Carbonate (–1.67 to 0.24 meq/L), and Permeability Index (42–102). IWQI values ranged from 66 to 72, classifying the water as "good" to "very good" for irrigation purposes. Sample M2 showed the highest BOD₅ (73 mg/L), indicating organic contamination, while M5 exhibited the most critical values for Na⁺, SAR, and %Na, signaling a sodicity risk. Principal component analysis explained over 90% of the variance, identifying EC, Na⁺, SAR, and %Na as key variables. Cluster analysis grouped the samples into two clusters: (M3, M5, and M7), showing sodicity risk, and (M1, M2, M4, and M6), with more stable parameters.n conclusion, irrigation water in Carchi is generally suitable for agricultural use, although specific locations exhibit signs of organic pollution (M2) and sodicity (M5), warranting continuous monitoring and preventive management.