[Bangkok - Tool & methods to increase the salt water solution efficiency in water supply of MWA]
Currently, the drought crisis in Thailand has been being intensified, resulting in less amount of water in the main dam. Normally, the freshwater is released from the dams of the Chao Phraya River basin for agriculture, consumption and it also helps push the seawater level away from raw water intake, but recently, the amount of released water has not been enough to push seawater causing saltwater intrusion to Sam Lae raw water pumping station. Thus, the seawater intrusion in raw water leads to increasing salinity of water supply. The Metropolitan Waterworks Authority (MWA) is responsible for the supply andservice of standard tap water for consumption, and therefore MWA has to solve this problem. However, the water use demand from the Chao Phraya River basin is highly up to 4.6 million cubic meters per day and MWA cannot find new raw water source. Besides, the water treatment plants of MWA were designed as conventional water treatment processes for surface water that is freshwater. Therefore, the water treatment plants cannot remove salinity from raw water; so, this solution was not effective enough. As a result, in certain times, MWA faces difficulty in treating saline water to maintain the standards.
For water supplied in Bangkok, Nonthaburi and SamutPrakan provinces
MWA develops a tool and methods to solve the saltwater problem that is more efficient and canreduce the impact. The development of tools requires integration of various data, both past andpresent, from both inside and outside the organization, such as data from numerous water quality and quantity analysisequipment installed in raw water sources, in order to an automatic salinity prediction model in the Chao PhrayaRiver 1-3 day in advance using LSTM (Long Short-Term Memory) tool. This could predict approximately 0.94 of Rsquaredand be a tool for planning and pumping raw water at an appropriate salinity level into raw water canal, which can reduce the number of raw water hours that are over-standardsalinity in March 2020 from 172 hours to 72 hours or representing a decrease of approximately 58 percent and adjustthe water production rate to suit the raw water pumping rate at the raw water pumping station that will not have an impacton customers. The aforementioned tool can be used to schedule and plan to effectively push the seawater away from theraw water pumping station by coordinating with the Royal Irrigation Department (RID). This is called the “Water HammerFlow Operation in the Chao Praya River”, letting large masses of water repel the high salinity wedge. RID increases released water/water diversion and opens the KhlongLat Pho floodgate during low tide (closedduring high tide) while MWA stops pumping raw water into raw water canal and adjust the water production rate to suitthe raw water pumping rate. This is how MWA copes with the seawater problem, which helps guide what to do next and set directions in seawater problem management.However, it would be great if there are more solutions to be discussed for this challenge.