When prolonged and excessive rainfall the more water percolates and the water table (below the earth surface/soil) rises. The higher the water table the more the possibility increases for a spring to form in the sense that it would now be easier for the water to find a means of escaping the underground through perhaps a crack or a cave, etc.
You are testing for the presence of starch: Iodine dissolved in an aqueous solution of potassium iodide - reacts with starch producing a deep blue-black color. This reaction is the result of the formation of polyiodide chains from the reaction of starch and iodine.
This is because it is a monocot and monocots do not have a vascular cambium in their stems.
Though there's no question in the statement above I would assume that you are asking about the pH of the water that is acidic. The correct statement would be:
Any liquid that has a pH less than 7 is called acidic, a pH above 7 is basic or alkaline.
The water in the swimming pool has a high acid concentration due to the chlorine which causes the effect of redness in the eyes.
