Investigation of saltwater intrusion in thach han river system by mike hydro river package

Saltwater intrusion is one of the most severe problems for worldwide coastal regions, leading to negative impacts on both human and aquatic inhabitant communities. Quang Tri province, located in the Central Coast region of Vietnam, faces consequences of saltwater intrusion because of its dense river network and El Nino phenomena’s influences. To analyse hydrological, hydraulic processes as well as investigate saltwater intrusion’s situation in this province, the authors adopted MIKE HYDRO River package and obtained results with good agreements with measured data from survey campaigns. The present conditions scenario shows that saltwater intrudes Thach Han and Cam Lo rivers with a distance of 25.35 km and 15.04 km respectively, where the salt concentration is under 0.75‰ and water can be drunk and irrigated. The large discharge of 30 m3/s can only push saltwater only 1.85 km to the sea, which is insignificant in comparison with the value of seawater wedge length, saltwater intrusion in Thach Han river system can only be mitigated slightly. Since the authors only consider hydrological droughts, future scenarios in 2030 and 2050 have slight differences with the present, where topography and river flow remain unchanged. Based on the above results, non-structural measurements are not recommended to deal with saltwater intrusion for both present and future scenarios, and local authorities should consider structural solutions, e.g. constructions of anti-salt dams, during the decision-making process.