A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1980

A multiple regression analysis is used to find the relationship between water shed area, A, average catchment rainfall, R, and annual streamflow, Q, of the small watershed area not greater than 1500 sq. km. The peak discharge estimated by TOMINAGA (1979) for the small irrigation project in Northeast is adopted to compute the peak discharge used for spillway design when the size of watershed area is known, the peak discharge per unit watershed area can be estimated from the graphs provided :(for 10, 20, 30 year s recurrence interval). Inlet drop spillway and Ogee spillways have been designed pass the peak discharge. Inlet drop spillway of 6-pipe row having a maximum diameter of 1.00 m can pass the peak discharge up to 39.5 ems when the dam height is 10.00 m. Ogee spill way having vertical and slope upstream face are selected in design. The crest length of spillways is upto 60.0 m. and the head of water over the crest ranges between 0.20 m and 1 .80 m, the peak discharge is upto 250 ems. Common outlet pipes have been designed to deliver water from reservoir to irrigation canals or the river. The size of pipe diameters are 0 . 20, 0 .30, 0.40, 0.50, 0.60 and 0.80 m. In some case this out let may be design in conjunction with a spillway for economy . Earth dams having the height upto 10.00 m have been designed. An earth canal with side slope of 1 vertical: 1 . 5 horizontal in section has been designed for distribution systems. Check, check drop and drop structures have been designed for on-farm system structures. 0 The 90 V-notch and the Cut-Throat Flume are devices used to measure the discharge in irrigation canals. The tables and graphed are investigated and provided for design purposes. These can be used t o expedite the design of all above structures.