indirect estimation of arvand river discharge using numerical modeling and remote sensing: a novel approach in water resources management

The river discharge is the most critical parameter in the hydrologic cycle, and its measurement is vital considering climate change and water resource management. due to local problems, the discharge of the arvand river, located in the middle east (hot-dry climate), has not yet been measured directly. the arvand river is considered the main source of freshwater inflow in the persian gulf and plays an essential environmental role in the northwest coastal zones of the persian gulf. for this reason, an indirect method was derived and used for the arvand river discharge in this study. this method estimates the river discharge based on the river plume dimension. for this purpose, numerical modeling extracted the relationship between river discharge and river plume area in the first part. thus, the persian gulf's temperature, salinity, and water circulation were modeled using fvcom. in the following, the sensitivity of the river plume to the discharge and wind was investigated more accurately by applying fourteen different wind modes plus eight different discharge modes to the model. the numerical model results indicate that the river plume of arvand is a surface-advected plume with a high sensitivity to wind fluctuations. numerous experiments extracted the mathematical relation between the plume area and the river discharge (pa-rd) within various wind conditions. a surface salinity of 37 psu determined the river plume border. the second step extracted the arvand river plume (salinity plume) area using remote sensing techniques. the linear relationship between the sea surface salinity in situ measurements and surface reflectance (sss-sr) of landsat tm5 satellite bands was obtained using a regression model at the river mouth in 1992. the surface salinity pattern at the arvand river mouth was revealed by applying the sss-sr relation to all of the landsat pixels. eventually, in 1992, the river plum (salinity plume) area was extracted, and then by substituting it in the pa-rd relation, the river discharge was estimated at 540 m³.s^-1. the present work is the first serious step toward studying the arvand river discharge.