Reliability analysis of trickle emitter clogging using Weibull distribution

Clogging in drip emitters inhibits the hydraulic performance of a drip irrigation system. The variations in emitter clogging over time have to be statistically modeled in order to study its impact on uniformity of water application and to forecast the required de-clogging treatments. An experiment was carried out in an existing drip irrigation system laid in a farmer's Areca-nut orchard in Coimbatore, India. Discharge rates of trickle emitters from the field were measured for a period of 20 weeks. Data were analysed for clogging rates and their temporal variations at four levels of emitter clogging: 5%, 10%, 15%, and 20%. The Weibull theory was applied for fitting the temporal variations in emitter clogging caused by the saline nature of the irrigation water. A computer program in 'C' language was developed to estimate the Weibull parameters using the least square technique. The validation of the Weibull model for fitting the temporal distribution of emitter clogging was carried out with the help of the Chi-square test at the 5% level, which confirmed the goodness of fit. The Monte-Carlo method was used to simulate the time for clogging of emitters at different levels. The number of times de-clogging is required to keep the emitters within 5% clogging was found to be 11 per year for the selected drip irrigation system. Similarly the treatments required for 10%, 15% and 20% clogging limits were found to be 7, 5 and 4 times per year respectively.