Reconstructing a mid-Holocene hydrographic network in the great Rann of Kutch and its role in Dholavira's maritime links

Dholavira, one of the most advanced Harappan cities, flourished on the island of Khadir in the Great Rann of Kutch (GRK), a vast, tectonically active salt marsh in western India. The presence of this large Bronze Age metropolis within the GRK and the GRK's role in its maritime trade remain open questions. In this study, we combine sediment texture analysis, optically stimulated luminescence (OSL) dating, and provenance fingerprinting using detrital zircon U-Pb geochronology and Sr-Nd isotopic ratios to reconstruct the mid-Holocene hydrographic network in the eastern GRK and its connectivity to the Arabian Sea. Our findings reveal that an ephemeral river system, likely a distributary of the river Nara, created a transient estuarine corridor during the Mid-Holocene sea-level highstand, enabling sediment transport from Indus-derived sources mixed with local materials from the GRK islands. Detrital zircon age spectra confirm provenance links to recycled Thar Desert sands enriched with Indus detritus, supporting a dynamic fluvial network that periodically connected inland areas to coastal waters. This ephemeral connectivity likely provided a maritime link that enabled Harappan traders from Dholavira and nearby cities to access Arabian Sea trade routes. Our results resolve the longstanding debate about GRK's paleo-environmental role and demonstrate how subtle, monsoon-driven fluvial systems facilitated one of ancient history's most advanced maritime trade networks, thereby refining our understanding of the Harappan civilization's geographic reach and economic strategies.