The 2018 Hokkaido Eastern Iburi Earthquake (Mj 6.7) caused numerous coseismic landslides (n = 7,837) covering over 700 km². This study aims to identify the post-earthquake morphological changes in drainage basins affected by the landslides, with particular interests in fluvial and slope processes. The study site is a catchment along the Atsuma River with less artificial modifications after the earthquake. Airborne laser scanning-derived Digital Elevation Models (DEMs) of October 2012 and September 2018, as well as unmanned aerial vehicle-derived multi-temporal DEMs and orthorectified images from April to October 2020 were collected. Based on these data, elevation change detection and analysis on geomorphometric parameters, including watershed geometry, channel networks, drainage patterns ,and stream profiles were conducted using geographical information system to characterize the post-earthquake morphological changes. We infer that, based on the increase in stream length and bifurcation ratio, channels on bare slope surfaces developed progressively to cause potentially higher surface runoff. With the interactions between fluvial and slope processes, as well as the assists by freeze-thaw actions on bare soil surfaces, further soil erosion and slope deformations are expected.

A higher level of campsite use generally results in a more extensive bare ground. Sustainable campsites must avoid unacceptable levels of bare-ground expansion and social crowding. Both the use level of the site and expansion of the bare-ground area are necessary parameters for identifying site sustainability. However, these data are not available for the 12 unmanaged campsites in Daisetsuzan National Park, northern Japan. Therefore, we measured the area of bare ground on each unmanaged campsite and analyzed the site sustainability of the three representative sites based on their use levels. First, we measured the area of bare ground on each of the 12 campsites using georeferenced aerial photographs in ArcMap 10.8.1. The area of bare ground on each campsite ranged from 46 m² to 3,603 m². Second, the Kuro-dake, Hakuun-dake, and Ura-Asahi campsites were selected to monitor the use level. We set up lapse cameras that took photographs of these three selected campsites every hour to record the daily site occupancy from July 12 to September 25, 2019. Among the three selected sites, the bare ground on the Kuro-dake campsite (394 m²) was the smallest, and that on the Ura-Asahi campsite (1,898 m²) was the largest. On the busiest day, one tent occupied only 8.8 m² on average in the Kuro-dake campsite. However, in the Ura-Asahi campsite, one tent occupied 146.0 m² on average. Management actions must be introduced to solve both overcrowding and overexpansion problems on campsites to enhance site sustainability.