Hydrothermal Memory of an Ancient Alluvial City: A Geomorphic–Urban Coupling Theory for Bogura, Bangladesh

Cities are normally studied as recent human constructions. Their thermal environment, drainage, land cover and infrastructure are usually modeled from contemporary variables such as building density, vegetation, road surfaces, rainfall and population. This paper proposes a different possibility: that a modern city may retain a measurable physical memory of landscapes that existed centuries or millennia before the present urban form. Bogura, Bangladesh, provides an unusually strong natural laboratory for testing this possibility. The modern city occupies a landscape shaped by the Karatoya and surrounding alluvial systems, while immediately to its north lies Mahasthangarh, an ancient urban centre whose environmental history has been reconstructed through geoarchaeological evidence. Previous satellite research has established substantial changes in the thermal environment of Bogura, while archaeological and geomorphological research has established long-term changes in the Karatoya system and the surrounding alluvial landscape. These research traditions, however, have largely remained separate. I propose the Ancient Landscape Inheritance Hypothesis (ALIH): the proposition that spatial differences in the modern thermal response of Bogura are partly controlled by inherited subsurface and geomorphic properties associated with former river corridors, alluvial deposits, drainage pathways and soil-moisture storage. To test this hypothesis, I introduce a proposed analytical construct called the Hydrothermal Memory Spectrum (HMS). Instead of measuring urban heat solely as an instantaneous difference in land-surface temperature, the HMS treats temperature as a time-dependent response to antecedent wetness, precipitation, vegetation state and urban surface conditions. The proposed framework combines historical geomorphology, archaeological evidence, multispectral and thermal satellite observations, radar observations, soil-moisture products, meteorological reanalysis, land-cover transition histories and targeted field measurements. The central statistical question is whether geomorphic inheritance modifies the temporal response of urban land-surface temperature to hydrological forcing after controlling for contemporary land cover, atmospheric conditions, elevation, seasonality and spatial dependence. No empirical results are fabricated in this manuscript. The paper establishes a falsifiable research program and identifies the measurements, models, controls and field validation required to determine whether ancient landscape structure remains dynamically observable in the modern urban climate. If supported and independently replicated, the framework could provide a general mechanism linking deep landscape history to present-day urban climate.