Hydrologic and Hydraulic Analyses of Falaj and Stormwater Related to the Construction of New Sohar Airport

Mohamed Abdel-Latif and Hossam Mahmoud

ABSTRACT

The Sultanate of Oman is located within the arid to semi-arid zone with no rivers and very little rainfall. In this region, water shortage represents the most critical challenge for development. Oman’s main source of water supply is groundwater from rich groundwater aquifer recharged by rainfall. Omani people utilize groundwater through shallow and deep wells and Falaj. Falaj is a system of a natural conveyance channels and series of maintenance wells. Most of existing Falaj have been constructed hundreds or even thousands years ago.

There are two types of Falaj; being surface Falaj (Ghaili Falaj) and deep Falaj (Iddi Falaj). Deep Falaj consists of numerous wells (shafts) which are connected by an underground open channel. The channel is usually between 0.5 m and 1.0m high, and 0.5m to 2.0m wide. The channel depth can reach 50m below ground surface and some Falaj extend as much as 120 km, and their perennial flow continues throughout the year.

The Sultanate of Oman will construct a new international Sohar Airport. The Airport site was set aside by the government of Oman and the Sohar Development Company to serve the future aviation requirements of the Batinah Region. The property is a large rectangle approximately four square kilometers on each side with an additional 1.5km x 1km extension to the south on the western half of the property. A Falaj (Falaj Al Awhi) originates on the western side of the southern half of the property and flows underground in two forks that join about 1.0 kilometer east of the proposed runway alignment. In addition, the new airport runway and facilities will be constructed several valleys and interrupt the natural surface water flow of stormwater.

This presentation summarizes the study of the hydrologic and hydraulic (H&H) performance of the Falaj system and stormwater management of the newly constructed airport. The H&H study objectives are to:

  1. Provide stromwater management and flood control for the new airport
  2. Provide continuous uninterrupted flow through Falaj system during and following the construction of the airport.
  3. Protect the quality of the groundwater conveyed by the Falaj system form pollution as it passes through the airport.
  4. Protect the quality of groundwater that infiltrate and percolate through the airport ground area recharge groundwater water aquifer from pollution.
  5. Provide adequate access to safely maintain the Falaj system within the airport area while maintaining airport security.

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