Predicting the Spatio-Temporal Evolution of DO and COD in the Bouregreg Estuary (Morocco): First Results

In Morocco, the Bouregreg estuary is located between Rabat and Salé at 34°2′9″N and 6°50′7″W, from its origins in the Middle Atlas Mountains to the Atlantic Ocean, it travels around 240 km. It is a part of a watershed with an area 9800 km2and an elevation range of 0 to 1627 m. This estuary is dominated by seawater, with minimal freshwater inflow for most of the year. Agricultural and industrial areas are located near the estuary mouth. Some urban sewage from Rabat and Sale is discharged directly into the estuary. According to our knowledge, there is no research on the water quality modeling in the Bouregreg Estuary. For the first time, dissolved oxygen (DO) and chemical oxygen demand (COD) are calculated in this study using an adopted 1-D numerical model (AQUASIM) based on reaeration rates and measured concentrations of DO and COD. Various statistical parameters were used to assess the accuracy of the AQUASIM model. The findings indicate that autumn has higher concentrations of DO along the estuary (from 3.18 mg/l at 7 km to 8.5 mg/l) than summer (from 2.97 mg/l at 7 km to 8 mg/l at the mouth). Additionally, from 39 mg O2/l at the mouth to 236 mg O2/l at 7 km, the average COD values increased. The present work will help to assess the variability and suitability of aquatic habitats, thereby providing enhanced information about the Bouregreg estuary ecosystem and a deeper understanding of its dynamics.