A One-dimensional Salinity Measurement Model in the Chao Phraya River with the Chao Phraya Barrage Dam Using a Shooting Method

Abstract

Sea water receding from the Gulf of Thailand causes salinity diffusion in the Chao Phraya River, Thailand, and the amount of northern water is reduced in the dry season. It has an impact on people, particularly the generation of tap water. The Samlae raw water pumping station is the major pumping station. The Ban Krachaeng subdistrict is located in Mueang district, Pathum Thani province, and is affected by saltwater intrusion, which causes the salinity level to exceed the recommended threshold. In order for the Metropolitan Waterworks Authority (MWA)'s water supply system to achieve the standard, the salinity index at the Samlae raw water pumping station is controlled to not exceed the surveillance threshold of 0.25 g/l in this research. A barrage dam consists of a number of large gates that can be opened or closed to control the amount of fresh water passing through. There is a Chao Phraya barrage dam which is across the Chao Phraya River at Chai Nat, the northern part of the focused area. The objective of this research is to demonstrate a onedimensional steady-state salinity measurement model in a river with a barrage dam. Irrigation is done in rivers with dams using the shooting method to estimate the solution. The results obtained from simulating simulated salinity measurements from Phra-Nakhon Tai Power Plant Station to Samlae Station demonstrated that the shooting method can be used to accurately estimate the solution. Freshwater flow velocity and salinity dissolving efficiency were discovered to be the most important elements controlling salinity levels. The suggested salinity control approach may help to regulate the salinity level until it reaches a normal level.