Abstract
Aim of study: The goal of this study is to analyse variations in curve number (CN) values produced by different cartographic data sources in a forested watershed, and determine which of them best fit with measured runoff volumes.Area of study: A forested watershed located in western Spain.Material and methods: Four digital cartographic data sources were used to determine the runoff CN in the watershed.Main results: None of the cartographic sources provided all the information necessary to determine properly the CN values. Our proposed methodology, focused on the tree canopy cover, improves the achieved results.Research highlights: The estimation of the CN value in forested areas should be attained as a function of tree canopy cover and new calibrated tables should be implemented in a local scale.
Highlights
The hydrologic response of a watershed in a rainfall-runoff event depends largely on the runoff threshold, which represents the volume of water that can be absorbed by the ground before surface runoff begins
Research highlights: The estimation of the curve number (CN) value in forested areas should be attained as a function of tree canopy cover and new calibrated tables should be implemented in a local scale
Even though the Soil Conservation Service curve number (SCS-CN) method has been widely studied for decades (NRCS, 2009), there are not several works focused on the validation of this approach in forested watershed
Summary
The hydrologic response of a watershed in a rainfall-runoff event depends largely on the runoff threshold, which represents the volume of water that can be absorbed by the ground before surface runoff begins It is an essential component of flood forecasting and warning systems (Carpenter et al, 1999). Even though the Soil Conservation Service curve number (SCS-CN) method has been widely studied for decades (NRCS, 2009), there are not several works focused on the validation of this approach in forested watershed. In this way, Kim & Lee (2008) concluded that the SCS-CN lookup tables depicts inaccurate runoff estimation especially in forested watersheds. Ajmal et al (2016) applied tabulated SCS-CN in forested areas and they confirmed that those tables were unreliable due to a runoff overestimation in all of their studied watersheds
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