Prehistoric Water Use in the American Southwest

1. Prehistoric Water Use in the American Southwest The Technology of the Hohokam, Anasazi, and Others By Chris McPhee Dept. of Anthropology University of Arizona

2. Key Players in Prehistoric Arizona • The Anasazi • Lived in the Four Corners region from 1200 BC until 1300 AD • Relied upon water conservation after settling into larger populations • Used water management techniques such as cobble mulch, checkdams, drainages, and gridded fields

3. Key Players in Prehistoric Arizona • The Hohokam • Lived in Central and Southeastern Arizona from 200 AD to 1450 AD • Intelligently managed the waters of the Salt and Gila rivers for irrigation agriculture • Used water management techniques such as canals and stream diversion

4. Location

5. Why is Water Important in Arid Environments? • The southwest US is an arid region, meaning that there is little available water • Precipitation can be very erratic • Water is the source of life in arid lands, plants and animals depend on it for survival (both wild and domesticated)

6. How was water harvested and used in Arizona during prehistoric times? Where did the water come from?

7. Water Use History in Arizona • Pre 2000 B.C.: Native American farmers rely upon dry farming techniques to raise newly imported tropical crops of corns, beans, squash, cotton and tobacco. Water access through rainfall and rivers. • By 1200 B.C. early farmers built canals to divert both floods and perennial flows from the Santa Cruz River into their fields. These canals are the oldest examples found in North America. • As early as 800 B.C.wells were dug in the Santa Cruz floodplain to tap high water tables.

8. AD 1100: Farmers shift fields to the bajadas above the Santa Cruz floodplain to apply rain runoff farming. Rock piling and terracing techniques are used in these elevated fields. • Late 1700’s: Farmers irrigating fields return excess surface water to the source river after irrigating. • Late 1800’s: Sam Hughes constructed a new, deep ditch to intercept water from the Santa Cruz river, now undercut to more than 20 feet below the floodplain surface. The ditch backfired due to heavy flow and ended up hurting local irrigation agriculture more than helping.

9. 1850’s-1860’s: The Gila River Pima, using water from the Gila River, produce enough surplus wheat and corn to feed nearly all incoming Anglo settlers. • 1860’s: Anglo farmers begin diverting water upstream on the Gila River from the Gila River Pima.

10. How did the Hohokam prehistoric people harvest water in the Sonoran Desert of Arizona that they occupied?

11. Hohokam Technologies • More available water in central Arizona in the form of perennial or seasonal rivers • Focus is on diverting surface water (from rainfall) to areas where it is needed (crops) • Settlements occur close to rivers to reduce the labor necessary to build canals

12. Canals and Stream Diversion (1000 AD)

13. Hohokam Canal Layout (circa 1000 AD)

14. Hohokam Canal Ruin at Present

15. Excavated Hohokam Canal Current Surface Courtesy of University of Arizona

16. How did the Anasazi prehistoric people (also called the Ancestral Pueblo) harvest water in the arid regions they occupied in northern Arizona?

17. Anasazi Technologies • Focused on preserving what little water there was. • Intent on capturing the rainfall and surface water that occurred on occasion.

18. Anasazi Cobble Mulch (1100 AD) Cobble Mulch = Stones provide shade, trap moisture, prevent evaporation, and prevent runoff of rain water.

19. Anasazi Drainages (900 AD) • Helps to direct water where people need it • Best if used in conjunction with natural drainages to capture the most water

20. Anasazi Checkdams (800 AD) Prevents water from flowing too quickly Allows better permeation of hard soils Helps in capture of surface water due to rains

21. Anasazi Gridded Fields (1100 AD) • Raised soil around edges traps water in specific field (like mini ponds) • Trees or crops planted in each unit • Prevents runoff from removing too much water during heavy rains

22. We live in a diverse planet with a variety of ecosystems and environments that challenge how people survive. How humans innovatively harvest water is what marks us as the intelligent, creative, and determined people we are.

23. What are other considerations that affect how humans harvest water?

24. Other Water Harvesting Technologies Used in other regions of North America, as well as South America • Climate considerations: Meant to cope with other problems besides arid climate • Technologies: Some technologies deal with climates that are too cold and wet • Geography: Others deal with obstacles presented by the topography of the land

25. Raised Bed Agriculture • Used in the 900’s by the Tiwanaku • Dries soil where the earth is too wet for crops to grow • Insulates crops against the cold ground

26. Other Technologies: Terracing • Popular in South America, even today • Used on steep mountainsides • Prevents rainfall from running off the mountain completely • Also provides a level platform for crops

27. How does water affect you in Arizona? • Do you live in an arid part of Arizona? (Find it on the map.) • Are there any rivers in Arizona? Are any close to you? Are your rivers dry most of the time?

28. How does water affect you in Arizona? 3. How do you get your water? Where does it come from? 4. Is rain important in your community? Why? 5. Do you harvest water? How could you? 6. Will Arizona always have water?