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Balinese Water Temple Networks
We draw on a time-honored agent-based simulation study to demonstrate two aspects helpful to understanding how integrated modeling may address resilience, simulating adaptation and network modeling. Lansing and Kremer (1993) describe an agricultural system in Bali that is dependent upon irrigation fed by rivers carrying rainfall runoff. Blocks of terraces are planted in rice. A tension with three main dimensions exists within the system involving a balance between yield, water use, and pest damage. Individuals seek to maximize yields, but if everyone plants each year, there would likely be insufficient precipitation to irrigate. Also, if farmers planted each block, pest populations can expand and severely reduce yields. In the 1970s, crop management was disorganized, all blocks were planted, plants were likely water-stressed, and pests reduced yields by up to 50 %, far greater losses than seen in the 1990s. Farmers are organized into groups called subaks, which
Fig. 9.2 Effects based on preliminary results of increasing or decreasing veterinary care on livestock in Mbaringon Samburu District, Kenya. The scenario included increasing or decreasing livestock survival by 3 % reflecting changes in care. Increasing veterinary care increased numbersof livestock per person (top, hashed line) and reduced the need for supplemental foods (bottom, hashed line)
coordinate to balance whether blocks are planted or in fallow. An intricate network of temples and shrines is present that promotes coordination. Whether crop yield would be highest if coordinated at very local scales, at the scale of the entire region, or at a scale similar to that of the temples was of interest to Lansing and Kremer (1993). Lansing and Kremer (1993 and cites therein) built an agent-based model of 172 subaks, with each containing information about the basin in which it occurs, where water is drawn from, and other information. The spatial connectedness of subaks was represented as a network, such that neighbors were aware of the management and crop performance of their neighbors. The simulation included estimates of rainfall, irrigation demand, rice growth stage, and pest load. Harvests varied in response to water stress and pest load. In early simulations, the authors found that subak-scale coordination reduced yields due to pests. Coordination across the region caused plants to be water-stressed. The coordination that was best was at a scale on par with that of temples and shrines that are located within subaks. But the authors continued to question how temple networks would form, and how they may coordinate cropping. Lansing and Kremer (1993) incorporated a learning component into their network. Subaks residents looked to neighboring subaks, and if the management system used produced greater yields, it was adopted. After initializing crop management to randomly selected systems, within a decade of simulated learning crop yields almost doubled. This clear example of simulating adaptation, and specifically irrigation within the Bali Temples system, has spawned expanded analyses (e.g., Janssen 2007; Lansing et al. 2009).
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