Extraction of fluvial networks from SPOT panchromatic data in a low relief, arid basin

Abstract

Euclidean distance classification of SPOT panchromatic data was used to delineate ephemeral, fluvial networks on low-relief, alluvial fan surfaces in an arid basin in the southwestern United States. The SPOT classified channel network was registered to a Universal Transverse Mercator (UTM) projection and compared to areas of channelized flow and a Strahler-ordered channel network extracted from U.S. Geological Survey 7½ minute topographic maps and black-and-white aerial photographs. One-pixel and two-pixel proximity searches of the SPOT classified image correctly classified over 80 per cent of the areas of channelized flow, 77 per cent of the second order and greater channel network, and 98 per cent of the fourth order and greater channel network. The SPOT channel network was simplified by elimination of lower-order channel segments to produce a network closely resembling (in terms of number of channel segments and total channel length) a network created for hydrological modelling from topographic maps. This suggests that SPOT panchromatic data can be used to delineate fluvial network for hydrological investigations in similar physiographic settings without existing topographic map or aerial photographic coverage.