Detection of Ancient Irrigation Canals in Deir El-Hagar Playa, Dakhla Oasis, Egypt, Using Egyptsat-1 Data

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Playa, Dakhla Oasis, Egypt, Using Egyptsat-1 Data Zaghloul, E. A. & S. M. Hassan and A. B.

1 JOINT US-EGYPT WORKSHOP ON SPACE TECHNOLOGY AND GEOINFORMATION FOR SUSTAINABLE DEVELOPMENT CAIRO-EGYPT, June 2010 Detection of Ancient Irrigation Canals in Deir El-Hagar Playa, Dakhla Oasis, Egypt, Using Egyptsat-1 Data Zaghloul, E. A. & S. M. Hassan and A. B. Mounir National Authority for Remote Sensing and Space Sciences (NARSS)

2 Abstract Dakhla Oasis is the second provincial oasis in Al- Wadi El-Gedid Governorate and lies about 198 km. north-west of Kharga Oasis. The Mid-Pleistocene lacustrine sediments exposed as erosional remnants in the Western Desert of Egypt provide evidence for a more humid climate than that which persists today. The persistence of climatic and hydrologic conditions amenable to maintaining a shallow freshwater lake would have allowed the region to be inhabited by a savanna fauna, as well as early human groups.

3 The most important playa is Deir El-Hagar Playa which located about 45 k. to the west of Mut (capital of the oasis) where the famous Pharaonic Deir El Hagar Temple is located. The extraction of geological features from satellite imagery is probably the most important objective of digital image analysis. The main aim of this work is to use High Pass Filter (HPF) image processing technique in order to enhance Egyptsat-1 satellite data to extract or mapping the archeological areas.

4 Bahariya Oasis Farafra Oasis Dakhla Oasis Kharga Oasis Fig. 1. The location of the study area

6 The present work deals with applying a high pass filter image processing technique on Egyptsat-1 data in order to enhance and emphasis the ancient irrigation canals in Deir El-Hagar playa which covers an area about 2.5 km and owed its water to the flowing natural springs located about 2 km to the south. The enhanced Egyptsat-1 images as well as the 3D prospective view prepared by draping the enhanced Egyptsat-1 over the ASTER Digital Elevation Model (DEM) with 15m spatial resolution indicate that the playa is semicircular basin that was covered by an extensive lake deposits

7 Although during the Neolithic pluvial period in the early Holocene when Terminal Paleolithic and Neolithic hunters and farmers spread over the Western Desert between 9500 and 5000 years ago, by 5000 BP with no rainfall, the lakes dried up and wind erosion under hyper-arid conditions has been the main process (Haynes, 1980) which forms the deflated playa surfaces in the western Desert in the form of Yarding.

9 Introduction Image processing software and hardware are becoming more efficient and less expensive. The use of more advanced statistics and probability theories in image processing in such neighboring disciplines as computer vision and artificial intelligence has also generated spill-over effect in satellite imagery interpretation.

10 Land Forms The area under consideration is nearly flat covering about 2.5 km with remnant of a recent playa in the form of Yardings. The playa abuts against a pediment surface which extends to the north-east and to the south-west. The pediment consists of a 30 m. succession of marl, shale, limestone, phosphate and sandstone of the Duwi Formation (Upper Cretaceous - Lower Maastrichtian- Campanian; Hermina et al., 1961). The deflated flat surface of the playa was dissected by an ancient system of irrigation canals from Roman and Pre-Roman times. Extensive areas in the nearby were cultivated depending on this water now covered by sand dunes and sand sheets.

11 Description of Deir El-Hagar Temple Deir El-Hagar, the Monastery of Stone, is a sandstone temple on the western edge of Dakhla Oasis, about 10 km from El-Qasr in the desert to the southern pediment of Gebel Eedmonstone and at the edge of the cultivated lands (Figs.1& 2). Edmondstone 1819 who is discovered the temple and found the temple half filled in with sand and he tried to clear it, though he soon abandoned the project and simply measured the structure. At that time, the sanctuary still had a roof and parts of three front columns were standing. After being buried in sand dunes and sand sheet for many centuries the temple has been uncovered, restored and partially reconstructed during the 1990s by the Supreme Council of Antiquities (SCA) and is now open to visitors.

12 The temple of Deir el-hagar represents one of the most complete Roman monuments in Dakhla Oasis. Dedicated mainly to the Theban Triad and to Thoth, construction of the temple began during the reign of the Roman Emperor Nero (AD 54-68), whose cartouche can be seen in the sanctuary. The walls also bear the names of Vespasian (AD 69-79) and Titus (AD 79-81) and the monumental gateway was decorated during the reign of Domitian (AD 81-96), although other Roman rulers have contributed to the decoration, with the latest inscription in the temple dating to the 3rd century AD.

13 In the immediate vicinity there is much evidence of agriculture in Roman times, including pigeon-houses. To the north-west of the temple is a Roman Period cemetery where crude human-headed terracotta coffins have been uncovered. The temple building measures 7.3m by 16.2m and has a well-preserved outer mud brick enclosure wall where some remains of painted plaster can still be seen. The main gateway is in the eastern side of the enclosure wall, while another gateway to the south, in the temenos wall of the sanctuary, depicts many Greek inscriptions and graffiti written by early travelers who wanted to record their visits to this sacred place.

14 (a) (b) Fig. 2 (a) Deir El-Hagar Temple Layout, (b) Deir El-Hagar Temple

15 Stratigraphy According to Zaghloul, 1999, three stratigraphic units identified (Table-1) within the playa sediments namely A- B and C at top are shown in (Table-1). The lower unit (A) is important because it contains Neolithic remains such as Lithic artifacts Bone fragments, Ostrich egg shell fragments. The total thicknesses of the exposed units are 3.10 m. It mainly consists of silt, sandy silt (Dikaka structure) sand and sandy clay with rare limestone pebbles and gravels. A 10 cm of burnet layer (Charcoal or Hearth) is located at the upper contact with the middle unit (B). Most probably, this surface represents a surface of living during the Neolithic time. A radio-carbon date gives the age of this charcoal sample to be 6500 B.P. (Haynes, personal communication).

16 General view of Deir El-Hagar Playa Playa Sediments and Dikkaka features

17 Some archaeological sites were recorded at the deflated surface of the playa. From the prehistoric studies of the Western Desert since the work of Catton-Thompson and Gardner (1932), Wendorf et al. (1980) Hassan (1978), Haynes (1983) and Zaghloul, It is clear that the record of changing climate and human occupation during the late Quaternary still incomplete.

18 Archaeological remains, pottery fragments and charcoal ( Hearth )

19 Table-1 Stratigraphic units identified within the playa sediments. (after Zaghloul, 1999)

20 At Deir El-Hagar playa, another site, 2 m below the above mentioned charcoal site, consist of aeolian sand inter-bedded with silt which includes Neolithic artifacts (Table 1). The works by Hassan (1978) and Wendorf et al. (1976) indicate that the Egyptian Sahara experienced a moist period from ca to 6000 BP. Probably during this moist phase, the playa was deposited. The dating of the charcoal sample from unit (C) substantiates this assumption. Table 2, is a paleo-climatic chart showing the archaeological succession and chronology for the western Desert (Haynes, 1983)...

21 Table -2 ; Paleo-climatic chart showing the archaeological succession and Chronology for the western Desert (Haynes, 1983).

22 Remote Sensing Convolution filtering A convolution kernel is a matrix of numbers that is used to average the value of each pixel with the values of surrounding pixels in a particular way. The numbers in the matrix serve to weight this average toward particular pixels. These numbers are often called coefficients, because they are used as such in the mathematical equations. Figure (3) shows the study area before and after applying the convolution filter. 57

23 Fig 3. Egyptsat-1 image before and after Appling the convolution filter with window 51x51

24 High-Frequency Kernels In this paper A high-frequency kernel with window (51 x 51) is used on Egyptsat-1 data in which a relatively low value is surrounded by higher values, like this the low value gets lower. Inversely, when this kernel is used on the the same image in which a relatively high value is surrounded by lower values the high value becomes higher. In either case, spatial frequency is increased by this kernel. Figure (3) shows high pass filter Egyptsat-1 image which emphasis the location of archeological sits. 56

25 Ancient Irrigation Canals Archaeological investigation has identified evidence of irrigation in Mesopotamia and Egypt as far back as the 6th millennium BCE, where barley was grown in areas where the natural rainfall was insufficient to support such a crop. Zaghloul, 1999 collect one charcoal sample suitable for radiocarbon dating within the semiplaya deposits. Ostrich egg-shell fragments and lithic-artifacts were found as deflated lag on the surface and appear to be derived from the pronounced erosional unconformity separating the playa mud from the semiplaya mud and sands.

26 Radiocarbon dating of the sample revealed a remarkable sequence of aggradation alternating with aeolian erosion and deflation and may represents a human living surface during that date. Zaghloul, 1999 detect the remains of the irrigation canals on the surface of the playa. These canals are the earliest record of irrigation in the period of Neolithic II (Table 2). Large scale agriculture was practiced and an extensive network of canals was used for the purpose of irrigation.

27 Enhanced derivatives Egyptsat-1 image shows the location of the temple and the traces of the ancient irrigation canals. Location of Deir El-Hagar Temple (1 ) - Remnant of ancient irrigation canals (2)- Source of water, Natural Spring ( 3) - Cultivated lands (4), Sand dunes (5) - Playa surface ( 6) and Edmonstone pediment (7).

28 The system comprises a network of irrigation canals gently sloping northward driven the water from the natural springs into the deflated surface of the playa (Figs.4 & 5). Most of these irrigation systems still exist undamaged up to now. The length of the main canal varies from m. to 2740 m. while the width varies from 4.5 m. to m.

29 Irrigation of fields at the level of the playa surface is implied by the remains of springs south of the temple. Over the centuries, the agriculture in the desert areas began to decay because of the salt in the alluvial soil, the sand dune encroachments and the lowering of the ground water level due to the climatic changes and the scares of rainfall precipitation in addition to the water over pumped.

35 Field photo showing traces of the ancient irrigation canals dissected the surface of the Playa

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