<p>At present, watersheds are encountering various adverse changes in their ecosystems, and their degradation has accelerated over time. This study aimed to evaluate the reliability, resilience, and vulnerability of the Talar Mazandaran watershed in Iran. The analysis utilized the precipitation concentration index (PCI), temperature condition index (TCI), and vegetation condition index (VCI) during the time frames of 2000–2010 and 2011–2021. Data from the Tropical Rainfall Measuring Mission and Terra satellite for rainfall, temperature, and vegetation were acquired for the 2000–2021 period and merged. The reliability (R_el), resilience (R_es), vulnerability (V_ul), and overall health (R_elR_esV_ul) indices for different sub-watersheds were determined. In terms of temporal changes, R_el, R_es, V_ul, and the health index were 11.97%, 13.66%, 5.15%, and 11.31%, respectively, higher in 2011–2021 compared with 2000–2010. In terms of spatial changes, R_el was 0.5 for all sub-watersheds. R_es varied from 0.23 to 0.34, with an average value of 0.27, corresponding to a relatively low-positive tendency. V_ul ranged from 0.56 to 1 and exhibited an average value of 0.78, corresponding to the relatively high-positive tendency. Finally, the health index varied in the range of 0.44 to 0.49 across different sub-watersheds, with an average value of 0.47, corresponding to the moderate-positive tendency. Given the impact of climate change, future research must evaluate the role of climatic factors, including temperature, the number of rainy days, precipitation type, and temporal changes in precipitation. This study’s findings can validate the use of remotely sensed climatic data in data-scarce regions for assessing watershed health.</p>