The Falaj system is an ancient water supply and distribution system used in several countries ranging from Morocco in the West to China in the East. While they are also discussed under the Persian name ‘quanat’, we are using the Arabic term, as our study site lies in Oman. The so called Daoudi Falaj collect groundwater, which is then channelled to places of consumption, mostly for irrigation within oases and plantations. There are more than 3000 Falaj still in operation alone in Oman, which are understood as a technique for sustainable use of water under semi-arid or arid conditions. Nowadays Falaj are under decline not only to the advent of additional sources (desalination), but also due to decline of groundwater discharge and of contamination.
Falaj Daris near the city of Nizwa, located inland Oman, belongs to one of five Omani Falaj that were inscribed by UNESCO on the World Heritage list in 2009. The total length of three channels amounts to about 8 km, delivering a discharge of up to 2000 l/s. The channels are connected to a clastic aquifer, located between the Hajar mountains in the North and ophiolite rocks in the South. The clastic aquifer has an extension of 6.5 km2.
For modelling of the Falaj we couple a 2D horizontal groundwater flow model with flow simulation of the network of 1D pipes. To our knowledge this is the first hydraulic model of an Falaj and its connected aquifer. It is set up by the COMSOL Multiphysics software and calibrated for aquifer transmissivities and inflow rates from the adjacent mountainous regions. We utilize groundwater and Falaj discharge measurements obtained from the Ministry of Regional Municipalities and Water Resources (MRMWR).
We present the model and its results. It is intended to include further data from observation campaigns. In a further step it is planned to extend the flow model by a transport simulation, which can be a useful tool to predict the spreading of contaminations.