Study of Intermittent-Irrigation Technique to Cropping Patterns and Water Availability at Pemali Kanan Irrigation Area in Brebes Regency

摘要

Paddy farming is closely related to irrigation water supply since it is a kind of plant that has a high water requirement. Therefore, in major areas in Indonesia, paddy is not recommended to be grown in dry season. In Brebes Regency, many farmers still pick paddy for all three planting seasons that they suffer from insufficient of irrigation water supply. The objectives of this study is to find out how water availability compared with water requirement at Pemali Kanan Irrigation Area in both periods (present time and 20 years to come) and is intermittent irrigation technique required to solve this water supply problem. This research is conducted by calculating water availabilty using FJ Mock Method, generating water availability for the upcoming 2 decades using Thomas-Fiering Method and analysing water requirements for all 13 cropping patterns. Output of the analysis shows that water availability of Pemali River in both periods are statistically identical. Meanwhile, the average water requirements are mostly negative. It means that water requirements for all 13 cropping patterns could be fulfilled by rainfall. The conclusion is that in most 2-weekly periods, rainfall could provide adequate water supply for all areas. Intermittent irrigation technique will only be required in a certain period that is the 3rd planting season which lasts from Juni to October.