The New Inland Sea

Scientific American | April 13th, 1907

The deep channel in the Alamo River, which passed Holtville in August, was gradually approaching Sharp's Heading, and it was recognized that when this cataract reached

The deep channel in the Alamo River, which passed Holtville in August, was gradually approaching Sharp's Heading, and it was recognized that when this cataract reached the heading it would be very difficult and expensive, and perhaps impossible, to maintain that heading. This, however, was not the only peril to the water supply of the valley. The channel of New River had eroded to such an extent that where the two streams separated it was estimated that four-fifths of the water was running down New River and only one fifth down the Alamo. While this proportion was favorable to the regimen of the Alamo and the safety of Sharp's Heading, it was very threatening in an other respect. It accelerated the cutting of the New River channel, in which was a great cataract four or five miles below the separation of the two streams, and this was, of course, advancing upstream. It was well recognized that when this cataract reached the Alamo the channel would be so deep that all of the water would run down New River and leave Sharp's Heading on dry land, without any water for the irrigation of the Imperial Valley. Threatened first with inundation, and next with the destruction of their entire water supply, the inhabitants of the Imperial Valley have naturally been almost in a state of panic for several months.

The Radical Groundwater Storage Test

Scientific American | October 19th, 2017

IN BRIEF California could better survive flood years and drought years by capturing floodwaters and using them to recharge underground aquifers that farmers and muni

IN BRIEF California could better survive flood years and drought years by capturing floodwaters and using them to recharge underground aquifers that farmers and municipalities now pump from when rains are scarce. To do so, water users and managers have to regard surface water and groundwater as one connected resource. A variety of test projects are proving that this approach can work. For example, farm fields can be flooded even when crops are growing so the water can percolate down into aquifers. Revising water rights and paying landowners to allow flooding can help the techniques work across California and the world.

The Rainfall Intensity-Duration Control of Debris Flows After Wildfire

American Geophysical Union (AGU) | May 23rd, 2023

The Science and Prediction of Post-Fire Debris Flows in the Western United States

U.S. Forest Service (USDA) | August 1st, 2017

Debris flows are among the most destructive hydrological consequences of fires in steep watersheds. The high likelihood of catastrophic wildfires in the western U

Debris flows are among the most destructive hydrological consequences of fires in steep watersheds. The high likelihood of catastrophic wildfires in the western United States and the encroachment of human activities into steep fire-prone areas have created the need to better understand, predict, and mitigate these hazards. This article highlights recent advances in understanding post-fire debris-flow generation and provides an overview of the evolution of hazard assessments in the western United States. Specific emphasis is placed upon free, publicly available toolsdeveloped by the U.S. Geological Survey (USGS) and available for analyses in support of Burned Area Emergency Response (BAER) and Emergency Watershed Protection (EWP) program activities. These tools consist of empirical models that predict the likelihood, potential volume, and the rainfall intensity-duration thresholds for debris flows in recently burned watersheds.

The season for large fires in Southern California is projected to lengthen in a changing climate

Nature Portfolio (Springer Nature) | February 17th, 2022

Southern California is a biodiversity hotspot and home to over 23 million people. Over recent decades the annual wildfire area in the coastal southern California region h

Southern California is a biodiversity hotspot and home to over 23 million people. Over recent decades the annual wildfire area in the coastal southern California region has not significantly changed. Yet how fire regime will respond to future anthropogenic climate change remains an important question. Here, we estimate wildfire probability in southern California at station scale and daily resolution using random forest algorithms and downscaled earth system model simulations. We project that large fire days will increase from 36 days/year during 1970–1999 to 58 days/year under moderate greenhouse gas emission scenario (RCP4.5) and 71 days/year by 2070–2099 under a high emission scenario (RCP8.5). The large fire season will be more intense and have an earlier onset and delayed end. Our findings suggest that despite the lack of a contemporary trend in fire regime, projected greenhouse gas emissions will substantially increase the fire danger in southern California by 2099.

The Uneven Nature of Daily Precipitation and Its Change

American Geophysical Union (AGU) | October 19th, 2018

Rain falls unevenly in time, which can lead to floods and droughts. It is widely known that precipitation is uneven, but it is difficult to quantify. Here we develop a me

Rain falls unevenly in time, which can lead to floods and droughts. It is widely known that precipitation is uneven, but it is difficult to quantify. Here we develop a measure for the unevenness of precipitation: the number of the wettest days each year in which half of the annual rain falls. We apply this to rain observed by gauges around the world. At all gauges combined, it takes only 12 days each year for half of the rain to fall. We also apply the measure to climate model simulations, with projections for the rest of the century. In the climate model simulations, the change in future rainfall is even more uneven than rainfall today: In a scenario with high greenhouse‐gas emissions, half of the increase in rainfall happens in the wettest 6 days each year. Rather than assuming more rain in general, society needs to take measures to deal with little change most of the time and a handful of events with much more rain.

The Untapped Potential of California’s Urban Water Supply: Water Efficiency, Water Reuse, and Stormwater Capture

Pacific Institute | April 12th, 2022

In this assessment, we quantify the potential for a range of water strategies in urbanized parts of California to both reduce inefficient and wasteful water uses and expa

In this assessment, we quantify the potential for a range of water strategies in urbanized parts of California to both reduce inefficient and wasteful water uses and expand local water supplies. This assessment finds that urban water-use efficiency improvements could reduce statewide urban water use by 2.0 million to 3.1 million acre-feet per year (AFY). The reuse potential of municipal wastewater is 1.8 million to 2.1 million AFY, and the stormwater capture potential is 580,000 AFY in a dry year to as much as 3.0 million AFY in a wet year. Previous assessments have shown that these efficiency and supply options are more cost effective than traditional – and increasingly hard to implement – options to expand supply. Programs to tap this potential would tremendously help solve California’s long-standing water problems.

The value of marsh restoration for flood risk reduction in an urban estuary

Nature Portfolio (Springer Nature) | March 21st, 2024

Topobathymetric Model for the Central Coast of California, 1929 to 2017

U.S. Geological Survey (USGS) | August 2nd, 2018

To support the modeling of storm-induced flooding, the USGS Coastal National Elevation Database (CoNED) Applications Project has created an integrated 1-meter topobathyme

To support the modeling of storm-induced flooding, the USGS Coastal National Elevation Database (CoNED) Applications Project has created an integrated 1-meter topobathymetric digital elevation model (TBDEM) for the Central California Coast. High-resolution coastal elevation data is required to identify flood, hurricane, and sea-level rise inundation hazard zones and other earth science applications, such as the development of sediment transport and storm surge models. The new TBDEM consists of the best available multi-source topographic and bathymetric elevation data for the onshore and offshore areas in Central California. The Central California TBDEM integrates 70 different topographic and bathymetric data sources including LiDAR point clouds, hydrographic surveys, single-beam acoustic surveys, and multi-beam acoustic surveys obtained from USGS, NOAA, and USACE. The topographic and bathymetric surveys were sorted and prioritized based on survey date, accuracy, spatial distribution, and point density to develop a model based on the best available elevation data. Because bathymetric data are typically referenced to tidal datums (such as Mean High Water or Mean Low Water), all tidally-referenced heights were transformed into orthometric heights that are normally used for mapping elevation on land (based on the North American Vertical Datum of 1988). The spatial resolution is 1-meter with the general location ranging from Point Conception to the Golden Gate Bridge, and extending offshore to a depth of at least 15 meters. The overall temporal range of the input topography and bathymetry is 1929 to 2017. The topography surveys are from 2008-2015. The majority of the bathymetry is from 1996-2011. Some of the nearshore void zone (not covered by lidar or multibeam) was filled with NOS surveys dating back as far as 1929.

Toward a Resilient Global Society: Air, Sea Level, Earthquakes, and Weather

American Geophysical Union (AGU) | April 30th, 2019

Society's progress along the four corners of prepare, adsorb, respond and adapt resilience square is uneven, in spite of our understanding of the foundational science and

Society's progress along the four corners of prepare, adsorb, respond and adapt resilience square is uneven, in spite of our understanding of the foundational science and a growing sense that urgent action is needed. The resilience vignettes describe the meaning and impact of current and near‐term change in four major domains: human health impacts from air pollution, coastal inundation from sea‐level rise, damaging earthquakes in populated areas, and impacts from extreme precipitation. Given our understanding of the scientific principles, societal action, from preparation to adaption, will be critical in minimizing the negative impacts of today's changes. The unprecedented rates of change in today's Earth system argue for urgent action in support of a resilient global society.