Inflation Reduction Act of 2022

United States Congress | August 6th, 2022

Click "get document" for the entire bill. Scroll below to see its drought relief amendment.

Click "get document" for the entire bill. Scroll below to see its drought relief amendment.

Influence of agricultural managed aquifer recharge on nitrate transport: The role of soil texture and flooding frequency

Soil Science Society of America (SSSA) | June 9th, 2021

Agricultural managed aquifer recharge (Ag-MAR) is a concept in which farmland is flooded during the winter using excess surface water to recharge the underlying groundwat

Agricultural managed aquifer recharge (Ag-MAR) is a concept in which farmland is flooded during the winter using excess surface water to recharge the underlying groundwater. In this study, we show how different recharge practices affect NO3− leaching and mineralization–denitrification processes in different soil systems. Two contrasting soil textures (sand and fine sandy loam) from the Central Valley, Califor- nia, were repeatedly flooded with 15 cm of water at varying time intervals in field and soil column experiments. Nitrogen species (NO3–, NH4+, total N), total C, dis- solved O2, and moisture content were measured throughout the experiments. Results show that when flooding occurs at longer intervals (every 1–2 wk), N mineralization increases, leading to an increase of mobile NO3− in the upper root zone and leach- ing of significant quantities of NO3− from both soil textures (137.3 ± 6.6% [sand] and 145.7 ± 5.8% [fine sandy loam] of initial residual soil NO3−) during subsequent flooding events. Laboratory mineralization incubations show that long flooding inter- vals promote mineralization and production of excess NO3− at rates of 0.11–3.93 mg N kg–1 wk–1 (sand) and 0.08–3.41 mg N kg–1 wk–1 (fine sandy loam). Decreasing the flooding frequency to 72 h reduces potential mineralization, decreasing the amount of NO3− leached during flooding events (31.7 ± 3.8% [sand] and 64.7 ± 10.4% [fine sandy loam] of initial residual soil NO3–). The results indicate that implementing recharge as repeated events over a long (multiple-week) time horizon might increase the total amount of NO3− potentially available for leaching to groundwater.

Influence of fine particle content in debris flows on alluvial fan morphology

Nature Portfolio (Springer Nature) | December 16th, 2022

Alluvial fans are large-scale depositional structures commonly found at the base of mountain ranges. They are relatively soil-rich compared to the rocky terrains, or catc

Alluvial fans are large-scale depositional structures commonly found at the base of mountain ranges. They are relatively soil-rich compared to the rocky terrains, or catchment areas, from which their material originates. When frequented by debris flows (massive, muddy, rocky flows) they contribute significantly to local hazards as they carry focused, collisional, fast-moving materials across alluvial fans, unpredictable in size, speed, and direction. We research how fine particle content in debris flows correlates with directional changes, i.e., debris flow avulsions. Toward this, we analyzed field data from two neighboring alluvial fans in the White Mountains (California, USA) that exhibit dramatically different topographies despite their proximity and associated similar long-term climates. Informed by these measurements, we performed long-term and incremental alluvial fan experiments built by debris flows with systematically-varied fine particle content. We found that (1) decreasing fine particle content increases the variability of fan slopes and associated channelization dynamics, and (2) for all mixtures longer-term continuous alluvial fan experiments form more complex surface channelizations than repeated flows for the same total time, indicating the importance of both particle sizes and timescales on alluvial fan surface morphology.

Influence of temperature and precipitation variability on near-term snow trends

Climatic Change (Springer) | October 17th, 2014

Snow is a vital resource for a host of natural and human systems. Global warming is projected to drive widespread decreases in snow accumulation by the end of the century

Snow is a vital resource for a host of natural and human systems. Global warming is projected to drive widespread decreases in snow accumulation by the end of the century, potentially affecting water, food, and energy supplies, seasonal heat extremes, and wildfire risk. However, over the next few decades, when the planning and implementation of current adaptation responses are most relevant, the snow response is more uncertain, largely because of uncertainty in regional and local precipitation trends. We use a large (40-member) single-model ensemble climate model experiment to examine the influence of precipitation variability on the direction and magnitude of near-term Northern Hemisphere snow trends. We find that near-term uncertainty in the sign of regional precipitation change does not cascade into uncertainty in the sign of regional snow accumulation change. Rather, temperature increases drive statistically robust consistency in the sign of future near-term snow accumulation trends, with all regions exhibiting reductions in the fraction of precipitation falling as snow, along with mean decreases in late-season snow accumulation. However, internal variability does create uncertainty in the magnitude of hemispheric and regional snow changes, including uncertainty as large as 33 % of the baseline mean. In addition, within the 40-member ensemble, many mid-latitude grid points exhibit at least one realization with a statistically significant positive trend in net snow accumulation, and at least one realization with a statistically significant negative trend. These results suggest that the direction of near-term snow accumulation change is robust at the regional scale, but that internal variability can influence the magnitude and direction of snow accumulation changes at the local scale, even in areas that exhibit a high signal-to-noise ratio.

Landslides: Processes, Prediction, and Land Use

American Geophysical Union (AGU) | January 1st, 2006

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 18. Landslides are a constant in shaping our landscape. Whether by

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 18. Landslides are a constant in shaping our landscape. Whether by large episodic, or smaller chronic, mass movements, our mountains, hills, valleys, rivers, and streams bear evidence of change from landslides. Combined with anthropogenic factors, especially the development and settlement of unstable terrain, landslides (as natural processes) have become natural disasters. This book charts our understanding of landslide processes, prediction methods, and related land use issues. How and where do landslides initiate? What are the human and economic consequences? What hazard assessment and prediction methods are available, and how well do they work? How does land use, from timber harvesting and road building to urban and industrial development, affect landslide distribution in time and space? And what is the effect of land use and climate change on landslides? This book responds to such questions with: • Synopses of how various land uses and management activities influence landslide behavior • Analyses of earth surface processes that affect landslide frequency and extent • Examples of prediction techniques and methods of landslide hazard assessment, including scales of application • Discussion of landslide types and related costs and damages Those who study landslides, and those who deal with landslides, from onset to after-effects—including researchers, engineers, land managers, educators, students, and policy makers—will find this work a benchmark reference, now and for years to come.

Large and inequitable flood risks in Los Angeles, California

Nature Portfolio (Springer Nature) | October 31st, 2022

Flood risks in the United States have historically been underestimated, particularly with respect to human well-being and within low-wealth and marginalized communities.

Flood risks in the United States have historically been underestimated, particularly with respect to human well-being and within low-wealth and marginalized communities. Here, we characterize a fuller range of risks in Los Angeles, California, using a quantitative framework that intersects flood hazards from rainfall, streamflow and storm tides with measures of exposure and vulnerability including ethnicity, race and socioeconomic disadvantage. We find that between 197,000 and 874,000 people (median 425,000) and between US$36 billion and US$108 billion in property (median US$56 billion) are exposed to flooding greater than 30 cm within the 100-year flood zone, risk levels far above federally defined floodplains and similar to the most damaging hurricanes in US history. These risks are disproportionately higher for non-Hispanic Black and disadvantaged populations, burdening communities that may have greater challenges recovering and reinforcing socioeconomic inequities. Our framework creates opportunities for transparently and equitably reducing flood risks in urban areas.

Large-Scale Environments of Successive Atmospheric River Events Leading to Compound Precipitation Extremes in California

American Meteorological Society (AMS) | February 18th, 2022

Successive atmospheric river (AR) events—known as AR families—can result in prolonged and elevated hydrological impacts relative to single ARs due to the lack of reco

Successive atmospheric river (AR) events—known as AR families—can result in prolonged and elevated hydrological impacts relative to single ARs due to the lack of recovery time between periods of precipitation. Despite the outsized societal impacts that often stem from AR families, the large-scale environments and mechanisms associated with these compound events remain poorly understood. In this work, a new reanalysis-based 39-yr catalog of 248 AR family events affecting California between 1981 and 2019 is introduced. Nearly all (94%) of the interannual variability in AR frequency is driven by AR family versus single events. Using k-means clustering on the 500-hPa geopotential height field, six distinct clusters of large-scale patterns associated with AR families are identified. Two clusters are of particular interest due to their strong relationship with phases of El Niño–Southern Oscillation (ENSO). One of these clusters is characterized by a strong ridge in the Bering Sea and Rossby wave propagation, most frequently occurs during La Niña and neutral ENSO years, and is associated with the highest cluster-average precipitation across California. The other cluster, characterized by a zonal elongation of lower geopotential heights across the Pacific basin and an extended North Pacific jet, most frequently occurs during El Niño years and is associated with lower cluster-average precipitation across California but with a longer duration. In contrast, single AR events do not show obvious clustering of spatial patterns. This difference suggests that the potential predictability of AR families may be enhanced relative to single AR events, especially on subseasonal to seasonal time scales.

Levee Decisions and Sustainability for the Sacramento-San Joaquin Delta

University of California, Davis (UC Davis) | August 15th, 2010

Levee Failures in the Sacramento-San Joaquin River Delta: Characteristics and Perspectives

Texas A&M University | December 15th, 2011

Between 1850 and 1922, agriculturalists built 1,700 kilometers of levees to convert 250,000 hectares of tidal marsh to farmland where the San Joaquin and Sacramento River

Between 1850 and 1922, agriculturalists built 1,700 kilometers of levees to convert 250,000 hectares of tidal marsh to farmland where the San Joaquin and Sacramento Rivers enter the San Francisco Bay (the Delta). Drained, farmed and isolated from the water channels, the organic soils behind the levees subsided to elevations as low as 8 meters below sea level, turning "levees" into "dams" that hold back water constantly. Engineers built water transfer projects in the mid-20th century, transferring water from the south Delta to 25 million Californians who now rely on the "dams" accidentally converted into supply channels. In 1972, however, a levee failure caused a salt-water intrusion into the Delta, raising the prominence of the polemic Peripheral Canal which, if built would replace the levees in the trans-Delta water transport role. Levee failures in 2004 (the Delta) and 2005 (New Orleans) have re-ignited the debate, fueled by comments made by public officials who warned that the Delta levees posed more risk of failure than did the pre-Katina Louisiana levees. This background motivates two research questions: What are the social perspectives regarding levee failures of the experts managing the Delta; and what is the history of levee failures that might support their perspectives? The research employed Q-Method to identify and describe four social perspectives: Delta Sustainers, Abandon the Levees, Levee Pragmatists, and Multi-Purpose Levee Advocates. A critical element underlying differences among the perspectives revolved around the perceived history of failures of Delta levees. This dissertation employed semi-structured interviews, archival record searches, and historic map and aerial photograph comparisons to compile a history of 265 levee failures since 1868, many of which are referenced to location, segment, and levee type. In addition, the dissertation compiled a list of emergency repairs and successful flood-fights. The history of failures indicates that important levees of the Delta have performed significantly better than previously identified. Sharing these social perspectives and research results among the key actors addressing Delta issues may lead to improved consensus decisions.

Little Ice Age flood events recorded in sag pond sediments in the Carrizo Plains National Monument, California

Nature Portfolio (Springer Nature) | March 8th, 2024

In California, severe precipitation events (SPEs) are often associated with winter season atmospheric rivers. These SPEs can generate hurricane-scale precipitation, creat

In California, severe precipitation events (SPEs) are often associated with winter season atmospheric rivers. These SPEs can generate hurricane-scale precipitation, creating a variety of natural hazards such as floods and landslides. For California, the most complete SPE-flood record yet generated is a 9000-year paleoflood reconstruction from the Santa Barbara Basin (Du et al. in Mar Geol 397:29–42, 2018). Finding terrestrial counterparts to compare to the Santa Barbara Basin is a challenge in Southern California where lake basins are rare and the terrestrial spatiotemporal signature of SPE floods remains largely unconstrained. Here, we present five 1–2 m sediment cores from a sag pond along the San Andreas Fault in the southern Carrizo Plain. The most complete record (core CLPC21-4) was selected for a variety of chronological, sedimentological, and biological analyses. Principal Component Analysis on these data reveals two end member sediment unit types: event versus ambient sedimentation. We focus on the two thickest sediment units likely generated by SPEs. These two units (EU 1 and EU 2) are especially distinct within CLPC21-4, characterized by erosive bases, above average sand content, normal grading, low magnetic susceptibility, and low total organic matter. Moreover, they are visually apparent across all five cores within the sag pond and thin from source to sink. Age control for the two units is constrained by AMS 14C dates on discrete organic materials and supported by the identification of Erodium’s first appearance ca. 1750–1765 CE in the Santa Barbara region. Using these age constraints, we infer the maximum limiting age range for Event Unit 1 from 1470 to 1640 CE and Event Unit 2 from 1740 to 1800 CE. Within the limits of dating, site-specific proxy sensitivities, and inherent meteorological heterogeneity, we propose a probable correlation to Santa Barbara Basin flood events at 1525 CE and 1760 CE. Our results suggest that sag ponds may represent a viable and untapped paleoclimatic archive for California. Future work will focus on a latitudinal series of sag ponds to determine the spatiotemporal sequence and correlativity of SPEs in the sediment record.