A thesis submitted in partial fulfillment of the requirements for the degree of Master of E~gineering of the Asian Institute of Technology, Bangkok, Thailand.

Thesis (M.Eng.) - Asian Institute of Technology, 1972

Hydrologic events such as river discharge are often regarded as continuous processes. To make the analysis simple; hydrologists measure it at equal time intervals and assume the data obtained as discrete values. Using the same valid assumption, daily runoff records of Mae Ping River (Station Pl), Thailand, were obtained and analyzed. It was assumed further that daily flow observations in a particular month belonged to the same population. From these populations, samples of size n-years were drawn. Values of the mean, standard deviation, coefficient of variation, skewness coefficients, and serial correlation GO efficient of lag one, two, and three were obtained for each of the samples It was found that the relationships between the maximum positive and negative deviations of these statistical parameters in percentages of their long-term values, and the period of record used, can be described by the relation Y = Ýe{u221D}n where Ý and {u221D} are unknown constants, Y is the percent error, and n is the period of record used in years.