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Weathering processes of geologic materials and the inputs of dry and humid atmospheric depositions yield the chemical composition of runoff at the watershed. When the ocean component is dominant, the inputs of Na+ can produce pH reduction in runoff water. The sodium dominance index (IDS) was determined as an estimation of weathering rate and resistance to acid deposition on Cuyaguateje, San Juan y Martínez and Mantua watersheds. The results show that linear regressions of IDS with pH are not significant in Cuyaguateje watershed, but they are significant in Mantua and San Juan y Martínez watersheds. These results are evidence of acidification processes originated by atmospheric inputs of marine salts. The IDS value for all studied watersheds has good correlation with annual flow of bicarbonates. [ABSTRACT FROM AUTHOR]

A wide and detailed review of specialized papers about methods and diagnose index used to soil erosion assessment was done. It was evident the variety of existent methods that allow researchers to select between all of them, those that better satisfy their aims and data availability. Methods based on erosion landform mapping, evaluation and thematic mapping of factors that influence on erosion, field observations, radioactive isotopes, and modeling are described, being remarkable the importance of Geographic Information Systems (GISs) for developing some of them. The exposed methods are classified in qualitative and quantitative taking into consideration the result type they offer. The methods and diagnose index used to soil erosion assessment in Cuba during the last decades was reviewed. [ABSTRACT FROM AUTHOR]