1. Modeling Anasazi Water Distribution
John B., Haley G., Benjamin I.

2. Historical Background
Water key to the birth and development of society
Earliest methods incorporate land
Moved to logs and then iron (America)

3. Historical Background
American southwest is a fragile environment
Unpredictable rainfall
Initial water source = pooled water
Three popular methods emerged:
Planting crops where they could reach the water table
Dryland agriculture
Collecting runoff to irrigate fields
Channel-based irrigation used most frequently
Constructed dams
Constructed reservoirs
Deep cut arroyos developed

4. Historical Background
Water localities were exhausted
Erosion
Expansion
Drought

5. Model Setup and Initialization
GIS Data used to form an elevation plot of the Long House Valley
Each point has several data values denoting important data
Latitude and longitude
Elevation
Height of the water surface above that point
Initially, the water surface is set at an elevation of 45, so all points will elevation higher than 45 do not have water present at the beginning of the model.

6. Behavior Criteria of Simulated Water
Upon each iteration:
Raindrops are created at an amount determined by the global variable rain-rate and assigned to random x and y coordinates
Each raindrop moves to the location with the lowest relative elevation within the radius defined by global variable movement-radius
Rel-elev = elev + ( count turtles-here * drop-depth )
A fraction of the existing water drops, determined by the global variable evap-frac, are removed from the map to simulate evaporation

7. Behavior Criteria of Simulated People
Upon each iteration:
If insufficient water supplies are present at the current location, the family will move to a new location with more water resources.
After a set amount of time, defined by the variable max-time-since-water, the family will be removed from the map.
After a set amount of time, defined by the variable reprod-age, the family will sprout another family.

9. Preliminary Data Without People: With People: Variable Values:
rain-rate = movement-radius = initial-pop = 20
evap-frac = 4E people-radius = drank-per-tick = 5
Preliminary Data
Without People:
With People:

10. Current Problems
The current day American Southwest gets the vast majority of its water from the Colorado River System
Provides drinking water to over 35 million people
Primary source of agricultural irrigation in Colorado, Utah, New Mexico, Arizona, Nevada, and California (80-90% of water that is extracted)
Water usage is beginning to eclipse the available water supply
More water taken out than is being replenished naturally
The remaining ~10% of available water must sustain the industrial and domestic needs of the Southwest

11. Water Usage

12. Population Increase

13. Diversion of Flow
Starting in the 1920s, Western States began to construct dams and channels, diverting massive amounts of water to rising cities as well as agricultural centers
Since then, hundreds of dams have been built to irrigate previously arid areas
For example, the Hoover Dam impounds Lake Mead, the largest reservoir in the United States which provides water to over 20 million people and large areas of farmland

14. Parallels to Anasazi
Water necessary for agricultural-based food systems
Even though modern food systems have become more complex, they still rely on water and farming
There is a strong lack of knowledge about the future effects of water diversion
Water systems are very complex and difficult to predict
Population increases exacerbating stresses on water supply
Cost vs. Benefit Analysis
Current water prices do not reflect the true value of water, leading to unsustainable decision making and business practices
Anasazi similarly failed to appreciate actual value of water, treating it as if it was unlimited

15. Sources http://www.pnas.org/content/107/50/21256.full