Nacl content of river water at Chungliangchen varies with the flow and ebb of tide,being generally higher at low tide. This is attributed to the effect of drainage water which flows into the river at low Tide.The seasonal fluctuation of Nacl content of river is studied.Nacl content at high tide is highest between the second half of June and the first half of July.During this,period,the Nacl content ar high tide may exceed that at low tide in some years.The significance of this as regards irrigation and effect on crop is a discussed.