Geoarchaeological Methods for Landscape Reconstruction at the Excavation Site of Naga, Central Sudan

Geoarchaeological Methods for Landscape Reconstruction at the Excavation Site of Naga, Central Sudan

Geoarchäologische Methoden zur Landschaftsrekonstruktion an der Ausgrabungsstätte von Naga, Zentralsudan

Jonas Berking, Julia Meister, Burkart Ullrich, Michael Schott, Georg Kaufmann and Brigitta Schütt

DIE ERDE 142 2011 (3) Contributions to Geoarchaeology pp. 289-313

• Geophysical prospection – Terrain modelling – 3D visualisation – Arid environments

Fig. 1 The study site and its location in NE Africa. a: Location in Africa, b: Central places during the

Meroitic Period (including the capitals of the former kingdoms, Napata and Kerma), c: The city of

Naga, including pertinent features / Das Untersuchungsgebiet in NE-Afrika. a: Lage in Afrika,

b: Zentralorte während der Meroitischen Periode (einschl. der Hauptstädte der früheren

Königreiche, Napata und Kerma), c: Die Stadt Naga (mit erhaltenen Anlagen)

   The archaeological excavation site of Naga, remains of a Meroitic city, is located in the semi- arid region along the fringe of the north-eastern Sahel and the south-eastern Sahara desert, in central Sudan, 150 km north of Khartoum and 40 km south of the Nile. During its heyday the city was a highly developed central place, with a large population and a booming economy. Naga has been the object of archaeological research for several decades – and of geoscientific inves- tigation since 2008. The first step for the investigation was to select adequate methods that combine the advantages of various subdisciplines and approaches. The study presented employs techniques from terrain modelling, geophysics and environmental analytics to evaluate field data with the aim of a comprehensive landscape reconstruction.

1. Introduction 

  Naga was a major city in central Sudan from the 3rd century BCE (Before Common Era) to the 4th century CE (Common Era) (Wildung and Kröper 2006). The city was part of the Meroitic Culture, which developed in the Kingdom of Kush during the first millennium BCE. This kingdom had its first capital, Napata, north of the 4th cataract, but later moved it southward to Meroe, located between the 6th and 5th cataract (Adams 1974), i.e., the capitals of the Kingdom of Kush were founded in direct proximity to the Nile River. By contrast, the city of Naga was sit- uated in the remote hinterland away from the Nile. This considerable distance from any per- ennial freshwater source led to the construction of one of the most fascinating geoarchaeologi- cal objects at Naga: the open water-storage ba- sin known as the “Great Hafir” of Naga (Fig. 1). With 11 Figures and 3 Tables

1.1 Scope of the study 

  Geoarchaeology applies geoscientific methods to answer archaeological questions (Rapp and Hill 2006). The present study aims to apply methods from terrain modelling, geophysics and environ- mental analytics in order to generate a comprehen- sive landscape reconstruction primarily based on field data. Our main interest is to reconstruct the palaeo-topography during Meroitic times and to evaluate the different methods used for the study. The target area presented here is the “Great Hafir”, where the various methods applied to investigate surface and sub-surface topography have already been interlinked. Here information on the palaeo- topography and the combination with sub-surface sedimentological and geophysical approaches are already processed, which allows the reconstruction of the environmental situation in Meroitic times and the changes which have occurred since. 

1.2 Study site 

  The remains of the city of Naga are located on the right bank of Wadi Awatib, about 150 km north of the Sudanese capital Khartoum, and about 40 km south of the River Nile (Fig.1). Wadi Awatib is an ephemeral stream that drains an area of 2360 km² and enters the Nile between the 5th and the 6th cataract, close to the town of Shendi. The area is characterised by one rainy season per year occurring during summer. Aver- age annual rainfall totals 95 mm (Berking and Schütt 2011); its temporal variability and spatial distribution are virtually unknown. Most of the rainfall results from the northward shift of the Intertropical Convergence Zone (ITCZ), which produces short and heavy convective rain events (Berking et al. 2010). The groundwater table in the wadi is about 75 metres below the surface, measured in two wells close to the excavation site of Naga (Berking et al. 2010). The groundwater is of fossil origin and is not regenerated by present-day rainfall (M. Edmunds, pers. comm.). 

  Both sides of Wadi Awatib are flanked by escarp- ments formed in Cretaceous sandstones, rising up to 90 m above the valley bottom. These me- sas shape the open landscape, and Meroitic tem- ples and other sites such as Naga are often lo- cated directly at the footslopes of these ridges (Berking and Schütt 2011). Soils along the footslopes are red-brown Regosols, whereas in the upper part of the hillslopes and on top of the mesas soils show only initial development. Flu- visols predominate in the alluvial plain. In these Fluvisols, ascending soil water and evaporation cause the formation of sub-surface incrusta- tions (Berking and Schütt 2011). 

  The entire area is characterised by sparse, drought-resistant vegetation, adapted to the lo- cal climatic conditions and modified by land use. Acacia tortilis and Acacia mellifera are the most prominent tree species, occurring either as riv- erine forest or in little patches next to the river- beds, here associated with Astrebla s. and Pani- cumturgidum (Aktar-Schuster and Mensching 1993). Whereas the vegetation in the middle and lower course of Wadi Awatib shows the typical contracted pattern of drylands, a dense vegetation cover occurs in its headwater areas. 

  The founding of the city of Naga cannot be dated precisely. Its development possibly started in the 3rd century BCE (Wildung, pers. comm. 2009). Naga is regarded as one of the major towns dur- ing the late Meroitic phase. Meroitic society is characterised by both Egyptian and African at- tributes, and Naga also displays remarkable Hel- lenistic style elements (Wildung and Kröper 2006, Wolf et al. 2008). The site of the city in- cludes various constructions such as temples, administrative buildings and cemeteries. The city covers an area of about 1.2 km2 (121 ha) (Fig. 1c).

  Today the area is only sparsely settled by peas- ants or semi-nomads, who raise cattle and live on runoff-fed agriculture, cultivating sorghum in the floodplains of Wadi Awatib (Gabriel 1997). 

At least since Meroitic times, floodwater harvest- ing has been practised in the area, by collecting surface water in artificial basins, known as hafirs (Arabic: dig). Hafirs are dug into the ground. The resulting depressions are encircled by walls built of the excavated material. The use of small hafirs is still common in the area, and their water is pre- dominantly used for irrigation and for cattle farm- ing. The Great Hafir of Naga (Fig. 2) is located on the right river bank of Wadi Awatib, about 0.5 km upstream of Naga at the confluence of a minor tributary. Its construction dates back to Meroitic times; at present it is inactive owing to siltation (Kleinschrot 1984, 1986, Hinkel 1991). A similar hafir at Musawwarates Sufra, about 30 km NE of Naga, also dating from the Meroit- ic phase, was studied using geophysical and ar- chaeological methods (Scheibner 2004).

Fig.11 Reconstruction of the Great Hafir of Naga; (a) 2.5D block diagram (5 times vertically exaggerated) of the hafir; (b) a first-order approximation of the average depth of the inner basin / Rekonstruktion des Großen Hafirs von Naga; (a) in einem 2,5D-Diagramm und (b) einer ersten Näherung zur mittleren Tiefe des inneren Beckens 

of Figure 4. The block diagram is superimposed by the true coloured IKONOS image and is 4 times

vertically exaggerated. / Die Stadt Naga in einer 2,5D-Visualisierung. Die roten Fähnchen zeigen

die Messpunkte aus Figur 4. Das Blockdiagramm ist 4-fach überhöht dargestellt und durch eine

echtfarbene IKONOS-Szene überlagert. 

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