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

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

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

Historical Background Water localities were exhausted Erosion Expansion Drought

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.

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

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.

Preliminary Data Without People: With People: Variable Values: rain-rate = 30 movement-radius = 3 initial-pop = 20 evap-frac = 4E-5 people-radius = 10 drank-per-tick = 5 Preliminary Data Without People: With People:

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

Water Usage

Population Increase

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

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

Sources http://www.pnas.org/content/107/50/21256.full http://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2016/02/23220945/Map_colorado-river_wikimedia.jpg https://www.sciencedaily.com/releases/2012/05/120510224444.htm https://environment.yale.edu/publication-series/documents/downloads/0-9/107Fort.pdf http://www.pnas.org/content/99/suppl_3/7275.short http://www.nationalgeographic.com/west-snow-fail/img/WSF_charts_2048.png http://www-tc.pbs.org/cowboysindianslawyers/images/topicfeature/map_final.gif