In recent years, we have faced torrential rains in the coastal areas and due to these rains, we have witnessed the flooding of rivers and floods into the Persian Gulf, the amount of nutrient discharge from land sources to the environment of the Persian Gulf has changed. The Arvand river in the northern part of the Persian Gulf, which has emerged from the confluence of the Tigris, Euphrates, and then Karun rivers, is the wateriest river entering the Persian Gulf. The discharge of water from this river to the Persian Gulf is often seasonal and proportional to the rainfall fluctuations in the Tigris, Euphrates, and Karun rivers. The highest amount of its discharge is in the form of floods in the spring of every year, which originates from the flow of surface water. In April 2019, floods occurred in several provinces of the country, including Khuzestan province, and as a result, a large amount of freshwater entered the Persian Gulf through Arvandrud. Considering the importance of the environment of the Persian Gulf and the direct and indirect effects of the flood, this research aims to investigate the effects of this flood on the loading of nutrients in the coastal and offshore waters of the northwest of the Persian Gulf, in two time periods before the occurrence of the flood (September 2018) and after the flood (April 2019) has been taken place. Studying the trend of nutrient concentration changes and comparing the results with the period before the flood, as well as obtaining basic information from the waters of the study area to protect the sensitive environment and sustainable development of the Persian Gulf, shows the application of this research. Sampling was carried out in the two stations 1 and 2 and in the water, column depending on the depth of each station (surface, middle, and bed) and in the two time periods mentioned, by the Persian Gulf marine probe, affiliated with the National Research Institute of Oceanography and Atmospheric Sciences. To measure nutri