Geospatial Modelling Geomorphic Typologies of the Binahaan River, Philippines

Abstract

Certain characteristics defining fluvial geomorphology have been linked with a wide range of ecological events that generate effects on the vital components of river systems. The Binahaan River in Leyte, Philippines, is important for irrigation and potable water distribution but little research has been conducted about it. Our objective was to generate baseline data on the river by developing a model showing the geomorphic typologies of its 4.5 km portion. Using Rosgen’s classification, we identified 12 typologies with the following key parameters: entrenchment ratio, width-to-depth ratio, sinuosity, slope, and channel material. Typology B5c — denoting moderate values for sinuosity and the entrenchment and width-to-depth ratios, and low slope range with sand as channel material — dominated the stretch. Data show that while some parts of the river are covered with silt/clay, sand occupied 57% of the identified typologies. Furthermore, many parts of the stretch were moderately entrenched and had high width-to-depth ratios. Sand mining generally disturbed the river and caused lower recovery potential for affected areas than the rest of the stretch. The identified typologies of the Binahaan River will be significant components for future research focusing on biodiversity and its relationship with the river’s geomorphology.