In the museum (national water museum), there were different levels for water, such as tube level, glass level and triangular level. They were used by Iranian many years ago to determined level of water in different lands.
Also there were scaled water clocks in ancient Iran and after. Two famous scientists; Haseb Karaji (4 century AH, Isfahan) and Mahmoud Khojandi (4 century AH, Khojand) who are famous in innovation and maker of measuring and surveying earth slope equipment and qanat slope indicator have played an important role in history of Iran water.