1. The Cross-scale Interplay between Social and Biophysical Context and the Vulnerability of Irrigation-dependent Societies: Archaeology’s Long-term Perspective
Margaret Nelson, Keith Kintigh, David Abbott, and John Anderies NABO & LTVPP Resilience & Vulnerability to Climate Change Conference – 12 Dec. 2010

2. Issues Tradeoffs between Robustness and Vulnerability
How did the different physical and social infrastructures affect the persistence of farming societies

3. 3 Sequences – AD

4. Commonalities Semi-arid environments,
Corn beans and squash dominant crops.
Crops need more water than direct rainfall
Therefore all required infrastructural investments

5. Mimbres – Ditch Irrigation & Runoff

6. Ditch Irrigation Investment Physical Infrastructure
Construction & Maintenance Modest
Social Infrastructure
Land allocation system
Little for construction & maintenance
Little for water distribution

7. Ditch Irrigation Trade-offs
Robustness
Higher productivity
Commitment to place enables storage
Lower levels of community integration
Vulnerabilities
Dry Periods - rare climate events
Resource depletion – soils and faunal
Enables population growth toward population-resource imbalance

8. Zuni – Floodplain/Sand Dune Farming

9. Zuni (& Mimbres) Runoff Farming

10. Runoff Farming Investment Vulnerabilities
Physical Infrastructure – small construction little to no maintenance
Social infrastructure – land allocation, made worse by aggregation & nucleation
Patchy Summer Rainfall- spread fields
Vulnerabilities
Rainfall Timing
Dry Periods
Potential for population
growth to resource
imbalance

11. Hohokam Irrigation

13. Irrigation Investment
Physical Infrastructure
Very large construction
Very large annual maintenance
Social Infrastructure
Organization for Allocation
Organization for Management
Organization for Maintenance

14. Irrigation Robust to Vulnerable to Spatial & temporal
variability in precipitation
Vulnerable to
Dry periods
Floods that wash out headgates
Shortfall for tail enders
Inadequate organization for allocation
Failure to organize large scale labor for cleaning
Commitment to place/wild resource depletion

15. Notes
I’ve focused on agriculture but exchange and other factors are quite important in understanding the trajectories
All these systems last a long time
Ubiquitous trade-offs between robustness and vulnerabilities
Some commitment to place is entailed by agriculture
This enables population growth which can easily lead to a population resource imbalance