A Geomorphometric Approach to Estimate the Deterioration of Earthen Archaeological Sites by Rainfall and Diffusion Processes: The Huaca Chornancap (Eighth–14th Century <scp>ad</scp> ), Lambayeque, Peru

ABSTRACT Rain‐induced erosion processes can severely damage Earthen archaeological sites. Huaca Chornancap (HCH; eighth–14th century ad ) is a platform located in the Lambayeque region (Peru) exposed to seasonal rain due to El Niño Southern Oscillation (ENSO). We present data from a UAV‐based photogrammetric survey and produce a Digital Surface Model from which we compute selected morphometric parameters. Rills and gullyes affect the HCH steep flanks, whereas pits concentrates on the flat top. Slides induced by rain also affect the western flank. Results from a model evidence the HCH sectors where diffusive erosion processes are predicted to act over the next century. We determine a vertical erosion rates of 0.33 m/century by ENSO‐related rain, 0.13 m/century by splash erosion and &lt; 0.25 m/century by diffusion processes. Our findings emphasize the deteroriation of the HCH structural integrity. The methodological approach we propose may be applied to other earthen archaeological sites worldwide.