April 8 DCDC Water/Climate Briefing
Land-use Change and its Effects on the North American Monsoon
Southern Arizona and New Mexico receive 40-60% of their annual rainfall in the summer, as part of the North American Monsoon (NAM).
Modeling studies suggest that 15-25% of this rainfall first falls on Mexican land, is transpired by vegetation, and subsequently is transported northward across the border to the US.
The natural ecosystems in Sierra Madre Occidental and the adjacent Gulf of California are known for their rapid greening and large transpiration rates at the onset of the monsoon, which promote the recycling of precipitation back into the atmosphere and facilitate further rainfall.
Two primary human activities have dramatically changed the region’s hydrologic cycle and evapotranspiration rates: irrigated agriculture and deforestation for grazing activities.
Join us for a presentation of cutting-edge science and modeling!
As the River Runs Dry: The Southwest’s Water Crisis
By Brandon Loomis and Mark Henle, The Republic | azcentral.com
LAS VEGAS – The patroller stopped his water district truck and grabbed his camcorder.
“Here we go,” he said, sliding from the cab and pointing his lens at the fine spray of water and rainbow rising from pop-up sprinklers on the lawn of a low-slung ranch home.
“Thursday,” he spoke, recording the day as evidence. No watering allowed on Thursdays.
Welcome to the future, where every drop of Colorado River water is guarded and squeezed. Only here, in the city that gets 90 percent of its water from the fickle and fading river, the future is now.
The vast and highly urbanized Southwest, built on the promise of a bountiful river propped up by monumental dams, is up against its limits. Already tapped beyond its supply, the river is now threatened by a warming climate that shrinks its alpine source.
New DCDC Publication
Planning for Demand Uncertainty in Integrated Water Resource Management
Ray Quay, Decision Center for a Desert City
Because water supply and demand face equally uncertain futures, a strategy that considers their relationship and anticipates a range of possible future scenarios for these two fundamental aspects of water use might be the wisest approach for water resource managers.
Uncertainty has been a driving factor in water resource planning for several decades, particularly in arid regions and in those with a high degree of interannual variability in precipitation.
In the last few decades, anticipatory governance has emerged as an approach for planning under conditions of high uncertainty.
In shifting from a predict-and-plan approach, water resource managers are anticipating a wide range of futures, developing response strategies, and adapting to anticipated changes as needed.