ABSTRACT:

This resource contains soil and river-sediment branched glycerol dialkyl glycerol tetraether (brGDGT) measurements and air and soil temperature records from the central Nepal Himalaya. The brGDGT dataset includes 56 soil samples collected from depths of 0–200 cm and 15 river-sediment samples collected between 2015 and 2024. The sediment samples comprise seven post-Gorkha riverbed deposits, seven deposits associated with the 2021 Melamchi flood, and one non-flood riverbed deposit from Yangri Khola. Reported variables include sampling location and elevation, sample depth and classification, individual GDGT peak areas and concentrations, total organic carbon, MBT′₅Me, and BIT index values. The resource also includes 35 air and soil temperature logger series from 10 monitoring sites spanning 772–4,300 m elevation in the Melamchi Valley. Temperature records cover October 2022 through May 2026 and are provided together with daily, monthly, and annual summaries. Depth-stratified MBT′₅Me–elevation calibration statistics, sample-level residuals, metadata, data dictionaries, quality-control information, and reproducible processing scripts are included. These data support evaluation of how soil-derived biomarker signals record sediment source elevations following earthquake-triggered landsliding and extreme flooding in mountain catchments.

ABSTRACT:

The data were collected in the Helambu region of central Nepal as part of the "Nepal-FRES" (Frontier Research in Earth Sciences) project to document the impacts of the 2021 Melamchi Flood, aiming to understand its cascading nature, the legacy of the 2015 Gorkha earthquake, and fluvial adjustment to such an extreme sediment transporting event.

Polygon KML files of landslides, active river channels, and river terraces were mapped using 50 cm-resolution pre- and post-event Pléiades stereo satellite imagery. This data package comprises:

 Melamchi Khola Catchment (study area)
 Landslides before the 2015 Gorkha earthquake, between 2015 and 2020, between Nov 2020 and Oct 2021 (Melamchi Flood), and between Oct 2021 and Dec 2023
 Obscured areas in which landslide mapping is incomplete due to the existence of clouds and shadow
 River channel of Melamchi Khola in Nov 2020 and Oct 2021 (w/ the thalweg line in Oct 2021)
 River terraces in Oct 2021
 Forested areas in Nov 2020 and Dec 2023