Mapping buried paleogeographical features of the Nile Delta (Egypt) using the Landsat archive

Abstract

Abstract. The contribution highlights the use of Landsat spectral-temporal metrics (STMs) for the detection of surface anomalies that are potentially related to buried near-surface paleogeomorphological deposits in the Nile Delta (Egypt), in particular for a buried river branch close to Buto. The processing was completed in the Google Earth Engine (GEE) for the entire Nile Delta and for selected seasons of the year (summer/winter) using Landsat data from 1985 to 2019. We derived the STMs of the tasseled cap transformation (TC), the Normalized Difference Wetness Index (NDWI), and the Normalized Difference Vegetation Index (NDVI). These features were compared to historical topographic maps of the Survey of Egypt, CORONA imagery, the digital elevation model of the TanDEM-X mission, and modern high-resolution satellite imagery. The results suggest that the extent of channels is best revealed when differencing the median NDWI between summer (July/August) and winter (January/February) seasons (ΔNDWI). The observed difference is likely due to lower soil/plant moisture during summer, which is potentially caused by coarser-grained deposits and the morphology of the former levee. Similar anomalies were found in the immediate surroundings of several Pleistocene sand hills (“geziras”) and settlement mounds (“tells”) of the eastern delta, which allowed some mapping of the potential near-surface continuation. Such anomalies were not observed for the surroundings of tells of the western Nile Delta. Additional linear and meandering ΔNDWI anomalies were found in the eastern Nile Delta in the immediate surroundings of the ancient site of Bubastis (Tell Basta), as well as several kilometers north of Zagazig. These anomalies might indicate former courses of Nile river branches. However, the ΔNDWI does not provide an unambiguous delineation.

The Sacred Waterscape of the Temple of Bastet at Ancient Bubastis, Nile Delta (Egypt)

“…Ancient Bubastis had access to the Pelusiac and perhaps also the Tanitic branch of the Nile, although the exact course and chronology of these Nile arms have not yet been determined (cf. [36][37][38]; Figure 1b). The additional vicinity of the Wadi Tumilat, the traditional overland route to Sinai and Palestine, gave Bubastis a very advantageous geographical position.…”

Sandhills, sandbanks, waterways, canals and sacred lakes at Sais in the Nile Delta

“…The proposed younger channel has left a strong signal in satellite imagery and drill augers on the western side of the Northern Enclosure archaeological area. A Landsat 5 TM (thematic mapper) image of wavelength 5 (shortwave infrared; USGS, 2020) shows a dark band along the western side of the enclosure, almost parallel to it, due to relative water retention of sediments, and is most likely to be related to grain-size effects of buried river branches (see Ullmann et al, 2020; this Special Issue; Fig. 6).…”

Preface: Special issue “Geoarchaeology of the Nile Delta”

“…The study of Ullmann et al (2020) analyses Landsat remote sensing data, acquired between 1985 and 2019 for the entire Nile Delta, to detect surface anomalies that are potentially related to buried near-surface palaeogeographical features. Using the normalized difference wetness index calculated for months with low and high evapotranspiration, anomalies in the immediate surroundings of several Pleistocene sand hills ("geziras") and tells of the eastern delta were identified.…”

“…A pioneer in this field was Manfred Bietak who reconstructed the river courses of the eastern delta on the basis of the contour maps of the Survey of Egypt (Bietak, 1975). In the following years, the geoarchaeological survey of the Amsterdam University Expedition continued this line of research in the northeastern delta with more detailed investigations on the early historical periods of ancient Egypt (van den Brink et al, 1986;van Wesemael, 1988;de Wit, 1993). At the same time, the geological exploration, especially of the northern delta, progressed through the extensive drilling campaigns of the Mediterranean Basin Program of the Smithsonian Institute from 1985 to 1994, analysing a total of 87 boreholes on-and offshore.…”

“…In recent years further geoarchaeological ventures evolved in the Nile Delta. To name two, the "Delta Survey" of the Egypt Exploration Society has created a database available online of all visited tells throughout the delta, which is continually updated (Wilson and Grigoropoulos, 2009;Spencer, 2016), and it is also worth mentioning that there is the ongoing geoarchaeological exploration of the sacred landscape of Bubastis being carried out by the University of Würzburg (Lange- Ullmann et al, 2019Ullmann et al, , 2020.…”