Kwok, Chee Yan

Lee, Teang Shui

Mumin, Md Sham

Universiti Putra Malaysia Institutional Repository

UPM Research Report 1998: Volume 2INDICES OF PERFORMANCE FOR CONTINUOUSLYIRRIGATED RICE CULTIVATIONC.Y. Kwok, Md Sham Mumin and T.S. LeeFaculty of EngineeringUniversiti Putra Malaysia, 43400 UPM, Serdang, Selangor,MalaysiaKeywords: continuous irrigation, indices, performance.IntroductionMany rice farmers prefer to irrigate the fields continuously.Indicators of irrigation performance have been developed forupland irrigation or if it is used in rice rotational or intermit-tent irrigation is practised. When applied to continuous irri-gation extremely low efficiencies result. The aim of irriga-tion is to maintain the water at a predetermined level. Basedon this premise, the water needed or wasted to maintain thistarget was used in the index.Materials and MethodsA plot was selected in the Kerian Irrigation Scheme (AlfredoValera et al. 1991) and all parameters contributing to thewater balance of the plot were measured continuously. Irri-gation inflow and outflow were measured using Parshallflumes. The water level in the field was also measured. Rain-fall was recorded using an Electronic Pluviometer. Evapo-transpiration was however measured manually each day. Allother values were data logged. These measurements weremade over one season.264Results and DiscussionThe design water depth was used as the criteria for irrigationperformance. Two indices were suggested. The first was Ef-fective Water Use index or EWUI, which is the ratio of Ef-fective Water Use to Effective Supply. The target value is 1.If it is greater than 1 then this indicates inadequate supply. Avalue less than 1 shows the insufficient supply. The second,the Plot Consumption Index is one minus the Drainage Sup-ply Ratio. The target value is 1. If it is less than 1 then it in-dicates over supply or excessive irrigation. If it is a negativevalue there is excessive drainage, which could result fromheavy rainfall or uncontrolled inflow from adjacent plots. Inthe study, values of PCI on a weekly basis showed an initialvalue of 0.12 increasing to a maximum of 0.68 at midseason.Both these indices were able to show when the plot was re-ceiving excess or insufficient water with regards to meetingthe target design water level.ConclusionsThese indicators could be used as indicators of irrigation per-formance (Nihal, 199I) at the plot level. However the valuesassigned as the criteria will initially need some familiarisa-tion by users.ReferencesAlfredo Valera and Mohd. Nor Bin Hj. Mohd. Desa 1991. Design-Management Interactions of Malaysia's Kerian IrrigationScheme. International Irrigation Management Institute (lIMI). p.1-64.Nihal, F. 1992. Monitoring Irrigation Water Delivery Performance:The Concept of Cumulative Relative Water Supply (CRWS).Advances in Planning. Design and Management of IrrigationSystems as Related to Sustainable Land Use. Belgium. 1992. p.525-534.Supported by lRPA Grant OI-02-04-0J31

Indices of performance for continuously irrigated rice cultivation

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Indices of performance for continuously irrigated rice cultivation

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