Morphometric analysis of the channel heads based on different LiDAR resolutions

Abstract

Due to a small size of channel heads it is difficult to determine their development without direct field measurements. Digital Elevation Models (DEMs) are often used for morphometric analyses of the drainage network in the wider spatial scale. The aim of the article is (1) to determine the possibility of using the high resolution terrain models (based on ALS and TLS) for morphometric analysis of such small forms as channel heads, (2) to create the classification of channel heads based on morphometric parameters resulting from different hydro-geomorphologic processes. The analysis of channel heads morphometry in the Bieszczady Mountains (Eastern Carpathians) was made on the basis of high-resolution DEMs (0.02 m) using a Terrestrial Laser Scanner (TLS). DEM of Differences analysis was used to obtain detailed morphometric parameters of channel heads. The analysis of the measurement uncertainty of channel heads morphometric parameters obtained on the basis of DEMs of different resolution and made using two LiDAR techniques (ALS, TLS) showed that for such a small landforms the reliable values of morphometric parameters was obtained on the basis of models with a resolution of not less than 0.1 m. In other cases the measurement error is above 5%. Most of the measurements based on ALS data are underestimated in relation to estimations based on TLS data, especially for small channel heads. Principal Component Analysis was the method of distinguishing of two basic morphologic types of channel heads: 1 – spring-fed channel heads, large and extended with uneven bottom resulting from soil creeping, and 2 – forms related to shallow subsurface flow, small and elongated, shaped by linear erosion. In total, 1505 m3 of slope material were removed from the analysed 16 channel heads. This indicates that, despite the small size, channel heads play an important role in the sediment fluxes on the slopes.