Restoration of Qaraoun Lake aquatic life based on wetland treatment concept

Qaraoun Lake, the largest artificial lake in Lebanon, suffered severe environmental issues due to discharging untreated domestic and industrial wastewater into it, throwing garbage, which transformed this lake into waste storage instead of using the water for agricultural purposes and making the surrounding places attractive for tourists as was before. Moreover, the violations on Litany River, Lebanon's main artery, also affected Qaraoun Lake. Therefore, this main reservoir suffers from annual blooms of potentially toxic cyanobacteria. Recently, tons of fish are washed up at the surface of the water, agricultural areas are irrigated with polluted water and the Qaraoun Lake is no longer an attractive touristic place. Besides, the climate change represented in lower precipitation and higher evaporation rates in the past few years in addition to the increase in the water demand due to the growth in the local population and the refugees from nearby countries have affected the vulnerability of the water sector in Lebanon. All these issues have resulted in the deterioration of the water quality, generating environmental issues, and seriously affecting the ecosystem. The purpose of this research is to investigate possible remediation strategies, which could help in the restoration of the Qaraoun reservoir. For this purpose, the Litani River water quality and hydrological data are collected from the Litani River Authority (LRA). Moreover, a hydrodynamic water quality model has been developed using Mike21 in order to restore the lake's aquatic life by eliminating the Litani River nutrients through constructed wetland concept, which reasonably simulated the water quality parameters of Qaraoun Lake. Consequently, the wetland could remarkably reduce the Litani River pollutants by 85%, 43.7%, 57%, and 56% for BOD, Phosphorous, Nitrate, and Ammonia, respectively. The resulted treated water, after passing the wetland, successfully improved the lake water quality and may lead to re-originate its ecosystem.