**Acknowledgements**

Thank you to the staff of the Department of Agriculture, Plantation and Forestry, Kendal Regency, Central Java Province and farmers who have provided information about the construction and improvement of tertiary irrigation networks. Likewise, we would like to thank all the staff of the Central Java of Assessment Institute for Agricultural Technology who have assisted in this survey, especially Mrs. Endah Winarni.

The survey activity for the improvement of the tertiary irrigation network on irrigated rice fields in Kendal Regency, Central Java was financed by the Indonesian Agency for Agricultural Research and Development, Ministry of Agriculture.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Appendices and nomenclature**

Indonesian farmers really need adaptation technology to climate change, especially farmers in paddy fields. One of the technologies for adapting to climate change is the improvement of tertiary irrigation networks in irrigated rice fields. The Indonesian government, especially the agriculture office, has data on irrigation networks (primary, secondary, and tertiary) and points for repairing tertiary irrigation networks. Determination of the point of improvement of the tertiary irrigation network is based on the possibility of primary and secondary irrigation networks, available water sources, and collaboration of water-user farmer associations and the government. Surveys of farmers using water after the improvement of the tertiary irrigation network show that the water source to meet the irrigation network greatly determines the commodities to be planted, the area of irrigation coverage, and the cropping index.

*Irrigation and Drainage - Recent Advances*
