The Monsoon Pattern Analyses on the Irrigation Water Balance

The water balance for irrigation is affected by conditional monsoon patterns, including the beginning of the season and the duration. In a technical irrigation service, the actual dynamic of monsoon patterns may influence the crop pattern schedule and the standard operating rule of irrigation intake. Some significant impacts on the water balance characteristics can enlarge the water deficit during drought periods and reduce the efficiency of crop intensity. Its significance can be detected by conducting hydrological simulations of water availability and water demand in certain seasonal periods. Hence, the updated crop pattern schedule and the standard operating rule of irrigation intake can be adjusted correspondingly. Moreover, the social conflict during the water distribution can be diminished, and water efficiency can be increased as well as the crop intensity. This study is conducted at Tibu Kuning irrigation area, West Lombok Regency, West Nusa Tenggara Province using 15 daily rainfall data for 25-year from 1993 to 2017. The results show that the monsoon shift pattern in the study area has an interval of 3-year with the maximum shifting period is about one month. Moreover, the monsoon shift pattern has affected the reliability of irrigation water services. In this situation, an adaptive crop pattern schedule needs to be updated to maintain agricultural productivities. Based on the results obtained in this study, updating of the crop pattern schedule and the standard operating rule of irrigation intake can be be adjusted for the upcoming periods. © Published under licence by IOP Publishing Ltd.