Developmental of pump operation and suspension criteria for optimum rainfall utilization.

Date

1984

Abstract

The study was conducted in the 3, 472-ha Libmanan-Cabusao Pump Irrigation System, Libmanan, Camarines Sur from the wet season of 1982 to the wet season of 1983 as one of the components of an integrated collaborative research project between IRRI and NIA. The general objective of this study was to determine was to determine a set of practically usable criteria for optimal pumping operations to best utilize different amounts of rainfall. The specific objectives were: (1) to determine the rainfall pattern and distribution within the service area; (2) to assess the actual effective rain-fall at different sections of the systems; (3) to determine the hydraulic response at selected points in the system when different number of pumps are in operation, and (4) to develop for the system a rational and practically operable schedule of pump operation and pumping suspension and/or cutback for different amounts of rainfall. Rainfall distribution in the service area is generally uniform for amounts equal to and greater than 8mm. Using the rainfall amounts measured at station 1, the corresponding mean rainfall for the system can be estimated; accounting for 81% of its variability. The heavy rainfall months are from July to December with the peaks concentrated in the months of July and November. The tail-end sections of the system showed the highest spill-way height of 88.3 mm in the wet season, and effective rainfall of 93.1% and 75.8% in the dry and wet seasons, respectively. Seasonal variations in spillway heights and freeboards in the system were not significantly different. On the average, the system had a high effective rainfall of 67%, spillway height of 72 mm and a freeboard of 48.7mm. Rainfall amounts of up to 50 mm can be considered 100% effective. Greater than this, adjustments have to be done to determine its equivalent effective amount. The systems need to operate fixed number of pumps and limit pumping manipulation in response to rainfall occurrences to adjusting its operating hours. Due to different cutback durations for the different sections, checks have to be implemented at the uppermost junction of the canals and use of HRTe of that location as the basis for the timing of the check. The remaining operating hours after a cutback should be tested against the HRTs for the irrigation sections if further operation is necessary. The suspension duration: Rainfall (SD:RF) ratio is dependent only on the irrigation schedule of a particular irrigation section.

Document Type

Master Thesis

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 995 1984 A2 S96

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