Data and code for "Dark fibre reveals contrasting subsurface thermal dynamics along a 40 km infrastructure corridor"

This record contains the processed data and analysis code supporting the manuscript **“Dark fibre reveals contrasting subsurface thermal dynamics along a 40 km infrastructure corridor.”** The study uses Brillouin optical time-domain reflectometry measurements acquired over approximately 54 days in summer 2021 along a deployed telecommunications fibre in southern China. The dataset supports comparisons among station infrastructure, buried farmland conduits, mountain trenches and tunnels, together with analyses of 17 mapped pond and ditch crossings and tunnel-overburden response. The deposit includes three analysis-ready MATLAB v7.3/HDF5 datasets; quality-control and installation-setting metadata; ERA5 hourly 2 m air temperature and precipitation series; derived statistical and plotting tables; Python scripts for the full-record, farmland, response-forcing, water-crossing and tunnel analyses; figure-reproduction code; and a MATLAB script documenting upstream processing from the original BOTDR matrix. Measurements are reported as apparent temperature change relative to the first acquisition. The native distance sampling interval is approximately 2 m, the instrumental spatial resolution is 20 m, and times are expressed in local time (UTC+8). The original interrogator output and complete raw BOTDR acquisition matrix are outside the scope of this record because of their volume and infrastructure sensitivity. See `README.md` for file descriptions, processing details, software requirements and reproduction commands.