In case ,you don't get what Ms. Sab said. )
You used 'the' when you are referring to A thing or A person that the listener knows what it is or who he is , or you have informed him from earlier statements.
A person walked in to my room . THE person then walked out . 'The' refer to that person you talk about in the first sentence (you have let him know who he is earlier).
The person who tell me a story will get a prize > Referring to that one person who tell him..
A person who tell me a story will get a prize> Referring to any person who can tell him.
Let us go to THE same place tomorrow ( you assumed he knows which place you are talking about ) There is only 'one' same place.
The Wayle means they is ONLY one river called 'Wayle' ,and its assumed you know which one since there is only one ,for example, The Great Wall of China , The British Museum ,etc.
THE park near my home > You can see that "the" here refers to THAT park that is near your house , not any other park , like The Bristish museum ( only ONE park that is near your house and he is talking about that and similarly only one British museum)
He is not talking about another river that cross THE park that is far away from your house , if there is one.
What is the Wayle? The Wayle IS a small river that cuts across THE park near my home.> This is to tell you that 'The Wayle' is one small river that cut .........( for your information, but there MAY BE other rivers like it and never said to you)
Which river cut across the park near your house ? The Wayle is THE small river that cuts across THE park near my home. > Here , he tells you that the Wayle is the only river , not any other rivers that cut ...