Even a very simple game-theoretic model provides major insight into these coupled social-ecological dynamics (Lansing and Kramer 1993). The model presented here simulates the effects of decisions about irrigation on the growth of rice and rice pests across the entire watershed. As time goes forward and selected patterns of irrigation schedules are implemented, local variations in rice harvests influence future decisions by the farmers, creating a coupled social-ecological system governed by feedback from the environment (Lansing et al. 2009).
Lansing JS., Kremer JN. 1993. Emergent properties of Balinese water temples: coadaptation on a rugged fitness landscape. American Anthropologist 95:97-114.
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In the beginning, each subak in the model is randomly assigned a schedule of crops to plant for the next 12 months, thus defining their irrigation needs. Then, based on historic rainfall data, the model simulates rainfall, river flow, crop growth and pest damage. Rainfall varies by season and elevation, and in combination with groundwater inflow determines river flow. Harvest yields may be reduced by water stress or pest infestations. Pest population density in each field depends on local plant growth, as well as dispersal from neighboring fields. At the end of the year, harvests are tallied, and each subak selects its cropping schedule for the following year by comparing its harvest with those of neighboring subaks, and choosing the schedule that produced the best harvests. Through this process of trial and error, subaks – within just a few years – form different-sized clusters that share interconnected cropping patterns. Groupings simulated by the model closely resemble the real clusters of subaks that coordinate their irrigation schedules via the water temple networks.
You can explore these behaviors (and their outcomes) in the app* below. Use the 'setup' button to establish a new simulation. Then use the 'go' button to start – and stop – the simulation.
Questions:
You can explore these behaviors (and their outcomes) in the app* below. Use the 'setup' button to establish a new simulation. Then use the 'go' button to start – and stop – the simulation.
Questions:
- What happens when pests grow quickly or slowly? Or when they stay local or disperse easily?
- What happens if the rainfall is low or high?
- What coordinated cropping patterns do you see under these different starting conditions?
References:
Janssen MA. 2014. Lansing-Kremer model of the Balinese irrigation system (version 3). CoMSES Computational Model Library.
Lansing JS., Kremer JN. 1993. Emergent properties of Balinese water temples: coadaptation on a rugged fitness landscape. American Anthropologist 95:97-114.
Lansing JS, Cox MP, Downey SS, Janssen MA, Schoenfelder JW. 2009. A robust budding model of Balinese water temple networks. World Archaeology 41:112-33.
* This app was written by Marco Janssen, Arizona State University.
Janssen MA. 2014. Lansing-Kremer model of the Balinese irrigation system (version 3). CoMSES Computational Model Library.
Lansing JS., Kremer JN. 1993. Emergent properties of Balinese water temples: coadaptation on a rugged fitness landscape. American Anthropologist 95:97-114.
Lansing JS, Cox MP, Downey SS, Janssen MA, Schoenfelder JW. 2009. A robust budding model of Balinese water temple networks. World Archaeology 41:112-33.
* This app was written by Marco Janssen, Arizona State University.