發送短信 : Time of concentration formulas for overland flow

 __   _     ______   _____      _____     ______  
| || | ||  /_   _// |  __ \\   |  ___||  /_   _// 
| '--' ||   -| ||-  | |  \ ||  | ||__    `-| |,-  
| .--. ||   _| ||_  | |__/ ||  | ||__      | ||   
|_|| |_||  /_____// |_____//   |_____||    |_||   
`-`  `-`   `-----`   -----`    `-----`     `-`'