Influence of hydrological element on qualitative-quantitative assessment of geodiversity for geosite recognition based on Western Samoa, SW Pacific

Geodiversity aspect concentrates on recognition and description of different elements of the abiotic nature, which range remains the same throughout majority of researchers; it includes geology, geomorphology, hydrology, climate, human and biological heritage (ex. Cultural objects and Fossils). However, here we decided to explore the hydrological aspect more precisely, which always mentioned but rarely described and/or implemented into assessment. Hence, we decided to explore it and calculate as an additional value for qualitative-quantitative assessment of geodiversity for geosite recognition. The assessment has developed based on the global parameter simply recognizable for two main elements geology and geomorphology, with an aim to highlight places of interest to minimize the area of field observation. Meanwhile, all other elements of geodiversity have considered as additional processes and materials which are influencing geological formation, where hydrology is setting eminent position.

            For assessment of hydrology, we concentrated on two of the most common parameters, which can be easily calculated from standard SRTM data: Strahler order and watershed basin. Strahler order is demonstrated streams as branch hierarchy, where the sources are considered as first order and the main river is the last possible order. The evaluation system is directly connected to Strahler order as the larges stream is likely to carry the most diverse variety of rock samples transported from the high elevation source areas. Additionally, watershed area parameters have been used as overlapping layer for the geological model to demonstrate what kind of rock particles can be transported by the river system in particular water basin. Hence, this research explores influence of hydrological element on results of qualitative-quantitative assessment of geodiversity based on territory of Western Samoa, which includes Savaii and Upolu Islands dominated by Holocene shield volcanos and post/shield scoria cones.