1-Introduction and Background
The geography of ancient Egypt and its mythology are closely connected, with the annual flooding of the Nile shaping both the physical landscape and the cultural worldview. In ancient Egyptian cosmology, the world emerged from a primordial watery void (Nun) as the first land, or "primeval mound". This study focuses on Esna, Upper Egypt, home to the Temple of Khnum and several other unexcavated or demolished temple sites. Inscriptions from the temple, such as the Festival of Seizing the Staff, metaphorically describe the local terrain as marshlands and document processional routes. While traditional Egyptological methods have correlated some text-based place names with physical locations, they often lack quantitative spatial analysis, leaving the precise geomorphological context of these narratives largely undefined. Macro-topography remains stable for a long time, barring massive modern anthropogenic intervention. This research adopts a landscape-first approach. By leveraging open-source geographic information systems (GIS) and remote sensing, we mathematically translate qualitative ancient texts into a DEM-driven topographic model to reconstruct the historical landscape that inspired the legends.

2-Study Area and Open Data Sources
The study area is Esna, with five documented temple sites surrounding it: Temple of Khnum, House of God, the Temple of Isis, and Kom Mir. The construction of the Aswan High Dam has masked historical paleochannels and floodplains; insufficient data are available for hydrological reconstruction. Consequently, this study heavily prioritizes Digital Elevation Models (DEMs). We lean on declassified 1960s CORONA panoramic stereo pairs to extract a pristine bare-earth microtopography, capturing the landscape long before recent agricultural expansion and infrastructure projects leveled it. We then complement this historical topographic baseline with decades of multispectral data from Sentinel-2 and the Landsat program (Landsat 1–9) to monitor remaining vegetation patterns and water indices. Aligning with the core philosophy of FOSS4G, our primary computational platform (QGIS) and all incorporated remote sensing datasets are entirely open-access.

3-Methodology
To bridge the gap between mythological narratives and spatial reality, we developed a reproducible, DEM-centric workflow using QGIS and Python spatial libraries. The best method we can use is layer analysis, which can turn qualitative contents into different GIS layers. The layers can be easily linked and operated with different calculations. The methodology includes three parts:
First, textual descriptions are converted into topologically validated GIS layers. Layer 1 represents the "Primeval Mound" (elevated, unflooded zones), Layer 2 represents "Marshes & Lakes" (low-lying retention basins), and Layer 3 delineates the "Western Mountains" (the absolute safety boundary).
Second, we execute rigorous Topographic Surface Modeling. Based on terrain stability, we use QGIS terrain analysis algorithms to compute critical geomorphological variables from the historical DEM. By calculating slope, aspect, Topographic Position Index (TPI), and the Topographic Wetness Index (TWI), we quantitatively define the physical landscape characteristics, isolating potential ancient mounds from natural depressions.
Third, we perform Hydro-conditioning and Simulated Routing. Since modern hydrology is severely disrupted, we reverse-engineer the ancient floodpaths through the terrain. We apply open-source algorithms to hydro-condition the DEM—executing pit-filling, flow-direction, and flow-accumulation routing—to establish a hydrologically correct surface. A terrain-based inundation algorithm, such as the Height Above Nearest Drainage (HAND) model, is then deployed. By routing simulated water levels across this stable topography, the inundation results are meticulously calibrated to match the spatial descriptions in the ancient texts.

4-Preliminary Results and Archaeological Implications
Currently, the DEM-driven spatial analysis successfully bridges the text-to-terrain gap. Our analysis of Layer 3 (the "Western Mountains") exposes a significant divergence between mythological narratives and physical geography. While the inscriptions describe this western margin as an impassable, absolute safety zone, the DEM analysis reveals it to be a modest ridge with an average elevation of only 200 to 300 meters. Furthermore, extracting elevation profiles from our decadal remote-sensing time series confirms that this topography has remained geomorphologically static, ruling out historical degradation. This discrepancy suggests that the ancient characterization was a phenomenological exaggeration, likely stemming from limited mobility and the imposing visual perspective of looking westward from the low-lying Esna basin. Identifying this spatial hyperbole is archaeologically significant; it demonstrates a broader tendency for cognitive exaggeration within the temple texts, providing a critical, data-driven foundation for reinterpreting other geographic claims in the inscriptions.
Our geomorphological computations explicitly identified elevated landforms and topographical depressions that align flawlessly with the text-derived topological layers. The hydro-conditioned HAND model effectively simulates the historical flood recession zones, demonstrating how rising waters would inundate the natural basins (Layer 2) and expose the structurally sound primeval mounds for temple construction (Layer 1).

5-Conclusion and Future Work
This study establishes a robust methodological blueprint for landscape archaeology. By pivoting from a purely hydrological focus to a terrain-driven analysis, we demonstrate how open-source GIS tools can bypass modern infrastructural disruptions to reconstruct ancient environments. The calibrated, DEM-based inundation model not only contextualizes the past but also serves as a predictive tool.
Future work will focus on:
First, we will broaden the temporal depth of our spatial database by incorporating and georeferencing early historical cartography (e.g., 18th- and 19th-century expedition maps). This process will cross-validate our findings and further corroborate the millennial topographic stability of the Esna geomorphology.
Second, we will expand our textual dataset—currently focused on the Festival of Seizing the Staff—to include inscriptions from other major local events, such as the Festival of Raising the Sky. Cross-referencing these distinct mythological narratives will allow us to generate additional topological layers and conduct rigorous statistical evaluations to assess their spatial validity and accuracy.

References:
[1] Sauneron, S. (1962). Le temple d'Esna. Tome V: Les fêtes religieuses d'Esna aux derniers siècles du paganisme. Le Caire: IFAO.
[2] Abdel-Raham, A. M. (2009). The Lost Temples of Esna. BIFAO, 109, 1-8.
[3] Assmann, J. (1996). The Mind of Egypt: History and Meaning in the Time of the Pharaohs. Metropolitan Books.