A groundwater flow model for water related damages on historic monuments – Case study West Luxor, Egypt

Abstract: In 1979 “The Ancient Thebes and its Necropolis” entered in the World Heritage List in a core zone of 7390 ha. Western Thebes holds the remains of about 36 temples in varying degrees of preservation and dating from archaic times (3100 – 2686 B.C.) to the Greco-Roman Period (332 B.C. – 395 A.D.). The temples of Medinet Habu, Ramesseum and Sethos I, are located in the western side of modern Luxor and are of special interest for this project. The Supreme Council of Antiquities (SCA), which belongs to the Ministry of Culture, has the main responsibility for all historical sites in Egypt. Research cooperation between SCA, the Department of Irrigation and Hydraulics at Ain Shams University in Cairo, and the Department of Water Resources Engineering (TVRL) at Lund University, was established as part of SIDA’s Swedish research Link program, for the purposes and realization of this project. Shallow groundwater is an important factor contributing to the deterioration of the Pharaonic monuments in Egypt. After the construction of the Aswan High Dam in the 1970s, the groundwater levels in many places along the River Nile valley have stabilized close to the ground surface (in Western Luxor between 0.5 and 4 m approximately). While the annual amplitude of the Nile was between 7 and 9 m before the High Dam was constructed, the amplitude today is approximately 3.5 m. The corresponding annual amplitudes for the groundwater level at Karnak Temple are approximately 4.5 and 1 m, respectively. The construction of the High Dam also meant that large quantities of water were used for irrigation of agricultural land. Since ancient times, the Nile has deposited layers of fine-grained alluvial soil several meters thick in the valley. The capillary zone of these soil layers reaches the ground surface, and constant transport of salts and water takes place in an upward direction due to evaporation. The result of this is a concentration of salts in the upper soil layers under and near the surface of the temple walls. The crystallization of these salts causes discolouring, and owed to the expansion during crystallization the building material can be crashed and the surfaces deteriorated. This combination of raised groundwater level, large irrigation schemes, and salinization, constitutes the problems encountered at the historic heritage sites. The main objectives of this research were to investigate the hydrogeological conditions at the West bank temples in order to identify where detailed field data is necessary for the success of a future groundwater model, and to propose engineering measures to lower the groundwater levels by at least 2.5 m, avoiding in this manner deterioration of the monuments caused by evaporation driven salt transport. The principal objective in the methodology was to use the available data to simulate the groundwater flow system in the specific area, using the computer code Modflow, which is an interface to the program GMS (Groundwater Modeling System), version 6.0. In order to improve the validity of the model, the access to reliable data related to inflows and outflows from the principal internal canals inside the model area is required. With a second set of field data, model verification could be completed and consequently the level of confidence of the model would increase. Results show that a reduction of irrigation rates over the model area is not sufficient to lower groundwater levels and it has to be combined with other measures, such as pumping and a better management of the internal canals and drainages flows. The fundamental problem is the raised groundwater table due to increased irrigation and reduced water level variations in the Nile, therefore, the most sustainable solution is to change or improve the irrigation systems in the area. Reducing urban and agricultural development impact is also important, and could be attainable with cooperation between local authorities, agencies and ministries.