Study of salinity variation in the Sebou River Estuary (Morocco)

Abstract

The Sebou river estuary is a coastal zone with an important agricultural area and is becoming one of the most important industrial zones in Morocco. However, salt water intrusion affects the economic development of the whole region. Therefore, determination of the salinity distribution along this estuary is the main interest for water managers. The aim of this paper is to study the spatial and temporal distribution of salinity in water course. Field measurements revealed that salinity intrusion depends on the state of the tide and on the upstream tributary waters from Lalla Aïcha Dam. The effects of the combination of various situations (dam closed–dam open and high tide–low tide) have been studied. A one-dimensional mathematical model has been used to simulate salinity distribution along the estuary. The model is based on one-dimensional equations of continuity, momentum, and salt transport in natural waters. Calculations of the river water level provided by the model are in good agreement with field measurements. Additionally, salinity simulations along the Sebou estuary for different hydrodynamic river conditions reproduce the observed salinity trends and contribute to a better understanding of this natural phenomenon. The model used permits a rapid assessment of salt water intrusion in the Sebou estuary and can help to ensure the safety of water supply and to support decision-making interventions.

Keywords:

• Sebou river estuary
• Salinity intrusion
• Mathematical model
• HEC-RAS

Acknowledgment

The authors gratefully acknowledge the technicians at the Water Service of Kenitra town and the engineers of the National Agency of Ports for their availability and collaboration. They also thank Mr Othman Khabali for his contribution to the field measurements.

Notes

Presented at the 7th International Conference on Water Resources in the Mediterranean Basin (WATMED7) 8–11 October 2014, Marrakesh, Morocco