Northeastern Qatari coast hydrodynamic modeling for assessment of sensitive ecosystems under anthropogenic and natural stressors

Abstract

The Northeastern Qatari coast, comprising diverse and sensitive flora and fauna communities (e.g. coral reefs and patches, seagrass meadows and turtles) is expected to undergo changes imposed by anthropogenic stressors (coastal development projects) in the near future. Therefore, the need to study the impacts of such scenarios on the existing ecosystems is pressing. Ecohydrological models are theoretical, mathematical representations of a natural system, made to understand the functionalities of the real ecological system under physical forcing. Using gathered data from sites, ecological associations are inferred and then combined to build a functional ecosystem model that mimics the real environment. These model systems are then used in order to assist the impact assessment of future scenarios on real systems. The aim of this study was to create hydrodynamic simulation along with a sediment transport model for a stretch of coastline off of Jabal Fuwairat. This aim was achieved using GEMSS modeler software, which requires the following data for a proper model (1) spatial data (that is included as shape files imported from ArcGIS), primarily the water body shoreline and bathymetry, additionally the locations, altitudes, and formations of man-made structures; (2) time-based data, that are varying in time (i.e. tidal changes, influx rate and temperature and meteorological data) and (3) Sediment composition. These data were collected and gathered into time varying data files that are loaded into a control file. A hydrodynamic model (HDM) simulating the spatial dynamics of the water was developed, calibrated and validated using field data. Additionally, a sediment transport model (STM) identifying, under present or simulated scenarios, the fate of the suspended sediment in the region and identifying potentially erosion and sedimentation area in the studied coastal zone is proposed. This STM assimilates data about sediment typologies, suspended particulate matter and currents near the seafloor (shear stress). Results from both HDM and STM models demonstrated that the study area is highly dynamic, being mainly controlled by tides and with relatively high shear stress (potential for erosion) in the northern and east-western boundaries. Considering these factors, the present research work intends to understand through a modeling approach the ecohydrological features of this area with special emphasis on the sediment dynamics and potential risks facing the sensitive coral reefs located in the area. This work provides three scenarios of future development that might take place in the area and shows the alteration of the dynamics of water and sediments accordingly. These simulations help the development of recommendations to decision makers for a better management of the considered coastal zone. It also provides a tool that can be replicated in future hydrodynamic studies along the Qatari coastal zone.