drawing water from Aridlands

Dalia Munenzon

On America's Great Plains, water in all states of wetness shapes both landscape and subterranean strata, bonding and holding down soil and flora. West of the 100th meridian, surface water is limited and annual precipitation on the plains is below 20 inches/ 50cm a year. As groundwater from aquifers is the primary source of life for any territory at the centre of agricultural production, the depletion of the Ogallala – the High Plains Aquifer – through hotter, drier and more unpredictable weather, jeopardises local ecosystems and communities. This invisible relationship between extraction, production, and the flow of natural resources is key to understanding future risks and opportunities for adaptation. Watershed-based readings of the landscape make these processes visible.

the High Plains Aquifer

Water from the saturated limestone sponge, the geological terminology for the aquifer, contributes to the annual production of $35 billion worth of crops, a quarter of national crop production. This remnant of an ancient ocean stretches from Texas to South Dakota and provides water to 112 million acres/4.6 million ha of farmland and grazing. Despite being deep underground, stationary groundwater and moving surface water are fundamentally intertwined as the aquifer discharges into streams and rivers. A decline in the aquifer's water level directly affects local streams that are drying at the rate of 6 miles per year.1

1 Ralls, Eric. 'The High Plains Aquifer Is in Danger of Drying Up' Earth.com, 15 Nov. 2017, https://www.earth.com/news/high-plains-aquifer-drying/.

Pumping for agriculture, industry, and residential use from the High Plains Aquifer started in the early 1900s, accelerating in the mid-century with technological developments in gas pumps. Since the 1950s, high-volume pumping has led to a water level drop of 325 billion gallons every year, between 9% and 30% of its volume, and is projected to lose 40% by 2070. With 90% of the water drawn being used for agriculture, the sustainability of long-term use is rooted in regional water management and use policies.

reading the landscape

In 1878, the geologist John Wesley Powell released his study on the farming and settlement capacity of territories west of the 100th meridian. In 'On the Arid Lands of the Western United States'2 he stated that there is insufficient surface water or precipitation to sustain European farming practices and that any farming will require irrigation. He proposed managing and dividing the territory based on watersheds, creating administrative structures based on the natural formation of the landscape to allow rational water distribution. His proposal was rejected. However, the projected climate changes and the rapid depletion of the High Plains Aquifer points to a concept worth revisiting.

2 Powell John Wesley et al. Report on the Lands of the Arid Region of the United States : With a More Detailed Account of the Lands of Utah. Belknap Press of Harvard University Press 1962.

cross-boundary recharging

The composition of sand and gravel in the High Plains Aquifer makes recharging complex and lengthy. Climate variability across the Great Plains, land cover changes and rate of water seepage result in recharge rates ranging from less than 1mm/year in parts of Texas to more than 150mm/year in the Nebraska Sandhills. This implies that the aquifer will take 6,000 years to recharge fully.

Each of the states across the HPA has different regulations for groundwater and surface water use. Some states view surface water as a public resource and groundwater as private property. There is an understanding between the neighboring state of shared ownership and responsibility over surface water resources. However, when one state is geographically located at the top of a watershed, its water use might dramatically reduce the access for the state at the lower basin of that river. Therefore, agreements are used to ensure the fair use of water between these states.

In an ironic twist, agreements are met by seeping HPA groundwater from one state and pumping it into river tributaries in another state. For example, Nebraska's

Cooperative Republican Platte Enhancement project involves purchasing retired farms and installing highcapacity wells to pump water from the HPA and pipe it to Medicine Creek.3 Despite regulations and policies that usually make a distinction between surface water and groundwater, this process causes an absurd situation in which a manufactured process increases the flow between the two – therefore introducing groundwater back into the 'regulatory' commons.

3 N-CORPE. (n.d.). N-CORPE, the Nebraska Cooperative Republican Platte Enhancement project. N-CORPE. Retrieved December 19, 2022, from https://www.ncorpe.org/

the commons as a commodity

Reducing the amount of water extracted for irrigation is connected to state and federal law, water rights, tax incentives, insurance mechanisms, and crop needs. Each state among the eight sharing the aquifer has rules and frameworks that allow (and unintentionally encourage) depletion. Water rights across each state both enable and limit use and distribution in various ways according to the flexibly defined 'beneficial use'.

In Nebraska, surface and groundwater are subject to public management and oversight. Groundwater is subjected to Correlative Water Rights, and Water First-inTime Rule limits surface water. An annual water assessment study evaluates comprehensive water conditions - ground and surface - per watershed. Kansas holds the jurisdiction of all water rights in its territory and allocates permits for use. In Oklahoma, groundwater use permits are issued per the land acreage held.

Texas differentiates between ground and surface water through rights given to landowners. Surface water is owned by the state and allocated by permits. According to the Rule of Capture, groundwater belongs entirely to the landowner overlying it - sometimes called the 'law of the biggest pump'– in a shared aquifer, over-pumping one property can impact neighbouring wells.

crops and stewardship

The Great Plains region has a strong connection to water and oil extraction. Post-WW2 industrialisation led to the development of technologies for these extractions, illustrated in the maps. They show the site, county, and extraction section on a large scale. The reliance on oil prices in agricultural production requires farmers to develop strategies for reducing their water demand when oil prices rise.

The crop type grown and how it is cultivated affects water demand. In the past, rising oil prices motivated farmers to explore new crops and diversify by combining perennial grasses to steer away from monocultures. Indigenous landscape management strategies and the integration of crops and livestock are rooted in the relationship between flora species and their support systems. Now, with the aquifer depletion, these practices should be re-examined. The main crops grown in each state are different in their water demand. From the 'thirsty' corn in Nebraska, consuming 22 to 30 inches of water per acre, cotton in Texas requiring 12 to 24 inches of water per acre, to grains such as sorghum, which only requires 15.5 inches of water per acre. As aquifer levels drop and droughts become more frequent, farmers adapt by reducing consumption and switching to drought-tolerant crops. Kansas farmers have reduced water consumption by a quarter without sacrificing profits, while West Texans are transitioning from water-intensive to drought-tolerant crops and grazing. Ultimately, decisions regarding planting and management are based on acreage and well capacity. Thus, removing the misguided notion of water abundance strengthens our understanding of ecological systems and relationships. And a closer relationship between the farmer, the soil, and the occupiers of his property.

Har vesting rainfall is becoming increasingly necessary in areas where recharge is nearly impossible and the water table is shallow. To effectively manage this deluge, it is essential to consider topography, large-scale watershed systems, and minor historical traces of water flow, such as draws. This vision requires collaborative management of resources between neighbours at a scale beyond just a single property. Reading the High Plains Aquifer environment through a watershed-geological lens is only complete by considering the final component of precipitation. p

Dalia Munenzon is an assistant professor of urban design in sustainable communities and infrastructure at the University of Houston Gerald D Hines College of Architecture and Design. www.daliamunenzon.com