The Library

Bali Runs Its Irrigation Through Temples

Bali schedules its rice irrigation through a network of water temples. It is a religious institution, and it works as engineering.

The island's farmers organise into cooperative units called subak, coordinated through temples that set the ritual calendar. That calendar decides who floods and who drains, and when.

In 1993 Lansing and Kremer modelled the system and found that simple local coordination rules reproduce the observed temple-based watering schedules. The schedules balance two things that pull in opposite directions: sharing a limited water supply, and flooding in sync so that pests lose their habitat at the same time across a wide area. Their field surveys found significantly fewer rice pests in subaks that fallowed in sync.

UNESCO inscribed the landscape in 2012 — roughly 19,520 hectares across five components, including the supreme water temple Pura Ulun Danu Batur — explicitly on the basis of the subak system.

The honest version: this has been argued over. A 2007 reanalysis found the self-organisation result depended on assumed pest dynamics and agent decision rules, and critics have argued the pest survey plots were too small to generalise from. So modelling and field surveys suggest the temples are doing coordination work. They do not prove a thousand years of priests were running a distributed computer.

We are also not repeating the common line that subak dates to the ninth century. The firmer anchor is a tenth-century inscription, and "firmer anchor" is doing real work in that sentence.

Sources

  1. Lansing JS, Kremer JN. "Emergent Properties of Balinese Water Temple Networks: Coadaptation on a Rugged Fitness Landscape." American Anthropologist 1993;95(1):97–114.
  2. UNESCO World Heritage Centre, "Cultural Landscape of Bali Province: the Subak System as a Manifestation of the Tri Hita Karana Philosophy" (inscribed 2012, ref. 1194rev).
  3. Janssen MA. "Coordination in irrigation systems: an analysis of the Lansing–Kremer model of Bali." Agricultural Systems 2007 — reanalysis contesting the result.