Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands

National Academy of Sciences (NAS) | May 5th, 2015

Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800–9

Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800–950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water- conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period.

Drought, Water Law, and the Origins of California's Central Valley Project

University of Nevada Press | October 27th, 2016

This book is an account of how water rights were designed as a key part of the state’s largest public water system, the Central Valley Project. Along sixty miles of the

This book is an account of how water rights were designed as a key part of the state’s largest public water system, the Central Valley Project. Along sixty miles of the San Joaquin River, from Gustine to Mendota, four corporate entities called “exchange contractors” retain paramount water rights to the river. Their rights descend from the days of the Miller & Lux Cattle Company, which amassed an empire of land and water from the 1850s through the 1920s and protected these assets through business deals and prolific litigation. Miller & Lux’s dominance of the river relied on what many in the San Joaquin Valley regarded as wasteful irrigation practices and unreasonable water usage. Economic and political power in California’s present water system was born of this monopoly on water control. Stroshane tells how drought and legal conflict shaped statewide economic development and how the grand bargain of a San Joaquin River water exchange was struck from this monopoly legacy, setting the stage for future water wars. His analysis will appeal to readers interested in environmental studies and public policy.

Drought, water management, and agricultural livelihoods: Understanding human-ecological system management and livelihood strategies of farmer’s in rural California

Elsevier | July 11th, 2024

Droughts impede water balance recovery from fires in the Western United States

Nature Portfolio (Springer Nature) | January 2nd, 2024

A steady rise in fires in the Western United States, coincident with intensifying droughts, imparts substantial modifications to the underlying vegetation, hydrology and

A steady rise in fires in the Western United States, coincident with intensifying droughts, imparts substantial modifications to the underlying vegetation, hydrology and overall ecosystem. Drought can compound the ecosystem disturbance caused by fire, although how these compound effects on hydrologic and ecosystem recovery vary among ecosystems is poorly understood. Here we use remote sensing-derived high-resolution evapotranspiration (ET) estimates from before and after 1,514 fires to show that ecoregions dominated by grasslands and shrublands are more susceptible to drought, which amplifies fire-induced ET decline and, subsequently, shifts water flux partitioning. In contrast, severely burned forests recover from fire slowly or incompletely, but are less sensitive to dry extremes. We conclude that moisture limitation caused by droughts influences the dynamics of water balance recovery in post-fire years. This finding explains why moderate to extreme droughts aggravate impacts on the water balance in non-forested vegetation, while moisture accessed by deeper roots in forests helps meet evaporative demands unless severe burns disrupt internal tree structure and deplete fuel load availability. Our results highlight the dominant control of drought on altering the resilience of vegetation to fires, with critical implications for terrestrial ecosystem stability in the face of anthropogenic climate change in the West.

Droughts in California

Public Policy Institute of California (PPIC) | April 1st, 2021

Drowned Memories: The Submerged Places of the Winnemem Wintu

Journal of the World Archaeological Congress (Springer) | July 7th, 2009

This article is a brief overview of an instance where landscape inundation has disconnected culture from place. The Winnemem Wintu, a Native American tribe in Northern Ca

This article is a brief overview of an instance where landscape inundation has disconnected culture from place. The Winnemem Wintu, a Native American tribe in Northern California, had most of their ancestral landscape along the McCloud River submerged by the construction of Shasta Dam just after World War II. The tribe’s remaining traditional cultural properties are under continual threat of loss and/or destruction, leaving the tribe’s ability to practice traditional ceremonies crippled by legal battles and fights against the continual assertion of United States hegemonic power over tribal cultural identity. As part of archaeological research on these submerged places, the tribe’s spiritual leader, Caleen Sisk-Franco, and Tribal Headman, Mark Franco, spoke with the author about these threats and how their culture must adapt to meet them.

Dry groundwater wells in the western United States

Environmental Research Letters (IOP) | July 28th, 2017

Declining groundwater levels are common in parts of the western US, but their impact on the ability of wells to pump groundwater is not known. Here we collate groundwater

Declining groundwater levels are common in parts of the western US, but their impact on the ability of wells to pump groundwater is not known. Here we collate groundwater well records for the western United States and present the recorded locations, depths, and purposes of more than two million groundwater wells constructed between 1950 and 2015. We then use the well records to estimate the percentage of wells that were dry during the years 2013–2015. During the two-year period, dry wells were concentrated in rural areas with high agricultural productivity, such as parts of the California Central Valley and the High Plains. Our results support anecdotal evidence that wells used for domestic purposes are more susceptible to drying than wells used for agricultural purposes throughout California’s Central Valley because the former tend to be shallower. However, this is not the case in all regions. Our findings suggest that declining groundwater levels are threatening drinking water reliability and agricultural productivity, and consequently, have key implications for both domestic and agricultural water security. Ongoing reductions to groundwater storage are drying groundwater wells in the western US, and this manifestation of water scarcity warrants innovative groundwater management transcending status quos.

Dry Me a River: Ecological Effects of Drought in the Upper San Francisco Estuary

University of California, Davis (UC Davis) | May 24th, 2024

Dry Year Program (1978)

California State Water Resources Control Board (SWRCB) | January 1st, 1978

The importance of water was emphasized to all Californians during the 1975-76 water year. A high pressure system persisted off the West Coast for months, preventing Pacif

The importance of water was emphasized to all Californians during the 1975-76 water year. A high pressure system persisted off the West Coast for months, preventing Pacific storms from depositing moisture on major areas of the State. As a consequence, the 1975-76 period turned out to be the third driest water year in recorded State history, being surpassed only by the droughts of 1923-24 and 1930-31. With most of the State•s surface reservoirs substantial l y depleted and meager prospects for normal runoff, Governor Brown - on the last day of 1976 - announced an eight-point drought emergency program. In effect, the emergency program marshaled the resources and personnel of all state agencies in an effort to ease, as much as possible, the social and economic impact on Californians if the drought should continue for a second year . As it developed, 1976-77 became the driest year of record, amply justifying the Governor's foresight. The State Water Resources Control Board (State Board) role in the emergency program was to develop a program of water conservation in cooperation with the University of California; to determine the quantity of water which could be expected in critically dry areas; and to protect the priority of uses of that limited supply in accordance with the State's water rights law. This was particularly important in the case of agriculture, the State's No. 1 industry. It appeared likely that the available supply of water would not meet the needs of farms and orchards for the full growing season or meet the full demand of municipal and industrial users and instream needs. The State Board was concerned that water users would inadvertently interfere with the water rights of others unless forewarned of the extent of availability of water to them. In addition, the warnings would be conducive to early implementation of conservation measures. The State Board established the Dry Year Program as a function within its Division of Water Rights ( Division) . This program, designed to protect and enforce the priorities of users of surface water had four objectives : 1. To identify critical drought-impacted areas in Northern and Central California. 2. To provide information on water conservation and shortage to diverters in these areas. 3. To assure that the limited water supply available would be used in accordance with established rights. 4. To take enforcement action against violations of permit and license conditions, illegal diversions and waste or unreasonable use of water.

Dynamic flood modeling essential to assess the coastal impacts of climate change

Nature Portfolio (Springer Nature) | March 13th, 2019

Coastal inundation due to sea level rise (SLR) is projected to displace hundreds of millions of people worldwide over the next century, creating significant eco

Coastal inundation due to sea level rise (SLR) is projected to displace hundreds of millions of people worldwide over the next century, creating significant economic, humanitarian, and national-security challenges. However, the majority of previous efforts to characterize potential coastal impacts of climate change have focused primarily on long-term SLR with a static tide level, and have not comprehensively accounted for dynamic physical drivers such as tidal non-linearity, storms, short-term climate variability, erosion response and consequent flooding responses. Here we present a dynamic modeling approach that estimates climate-driven changes in flood-hazard exposure by integrating the effects of SLR, tides, waves, storms, and coastal change (i.e. beach erosion and cliff retreat). We show that for California, USA, the world’s 5th largest economy, over $150 billion of property equating to more than 6% of the state’s GDP and 600,000 people could be impacted by dynamic flooding by 2100; a three- fold increase in exposed population than if only SLR and a static coastline are considered. The potential for underestimating societal exposure to coastal flooding is greater for smaller SLR scenarios, up to a seven-fold increase in exposed population and economic interests when considering storm conditions in addition to SLR. These results highlight the importance of including climate-change driven dynamic coastal processes and impacts in both short-term hazard mitigation and long-term adaptation planning.