GeoLedger: blockchain and GIS architecture for trusted emergency incident mapping

Most existing emergency management systems are centralized, leaving critical information vulnerable to unauthorized access, manipulation, and single points of failure. Blockchain has been extensively studied as a decentralized means of improving the security, integrity, and auditability of incident data. However, using full incident payloads on the blockchain is constrained by latency, throughput, and storage limits imposed by high-volume incident streams, which hinder real-time visualization and rapid decision-making. This paper presents GeoLedger, a blockchain–GIS architecture for secure, ledger-backed geospatial representation of emergency event data. In GeoLedger, incident data are first normalized by a registration authority before being compacted into signed metadata digests and content pointers anchored to a permissioned ledger. Incident narratives are then stored securely in off-chain repositories. The on-chain records are projected onto a GIS dashboard as interactive geospatial markers, enabling operators to inspect incident types, times, locations, and blockchain transaction identifiers without exposing full incident details to all participants. A prototype utilizing a custom Ethereum-compatible permissioned blockchain and a Python GIS layer was implemented and evaluated using replayed London Fire Brigade incident traces. The results show that GeoLedger attains average latencies of approximately 400 ms for incident-to-visualization and delivers a 20%–30% increase in sustained throughput at high incident rates compared with full-payload centralized and blockchain approaches. GeoLedger also yields significant reductions in the on-chain communication and storage required by committing metadata alone. The security analysis demonstrates that GeoLedger enhances integrity, accountability, and privacy against forgery, tampering, and unwarranted disclosure, supporting its deployment in large-scale, time-critical emergency operations.