Increasing importance of 2021 temperature as a driver of streamflow drought spatial extent

Environmental Research Letters (IOP) | February 9th, 2021

Widespread streamflow droughts can pose substantially greater societal challenges than spatially less extensive events because of the complex realities of trans-regional

Widespread streamflow droughts can pose substantially greater societal challenges than spatially less extensive events because of the complex realities of trans-regional water management. In a warming climate, drought spatial extent may change along with changes in underlying hydro-meteorological contributors. Here, we assess changes in streamflow drought spatial extent over the period 1981–2018 across the conterminous United States, and how the importance of potential hydro-meteorological contributors has changed over time. We first derive a monthly time series of drought spatial extent and look at trends in streamflow drought spatial extent. We then determine the spatial percentage 'overlap' of precipitation droughts, temperature anomalies, snow-water-equivalent deficits, and soil moisture deficits with the area under streamflow drought to look at the changing influence of these contributors on spatial extent. Our results show that (1) the spatial extent of droughts has increased, mainly because of increases in the extent of small droughts; (2) streamflow drought extents overall substantially overlap with soil moisture deficits and the relationship of drought to precipitation and temperature anomalies varies seasonally; and (3) the importance of temperature as a contributor to drought extent has increased over time. We therefore conclude that continued global warming may further increase drought extents, requiring adaptation of regional drought management strategies.

Increasing water cycle extremes in California and in relation to ENSO cycle under global warming

Nature Portfolio (Springer Nature) | October 21st, 2015

Since the winter of 2013–2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and

Since the winter of 2013–2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and an extraordinary increase in wildfires. Identifying the effects of global warming on regional water cycle extremes, such as the ongoing drought in California, remains a challenge. Here we analyse large-ensemble and multi-model simulations that project the future of water cycle extremes in California as well as to understand those associations that pertain to changing climate oscillations under global warming. Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century; this projected increase in water cycle extremes is associated with a strengthened relation to El Niño and the Southern Oscillation (ENSO)—in particular, extreme El Niño and La Niña events that modulate California’s climate not only through its warm and cold phases but also its precursor patterns.

Independent Review Panel (IRP) Report for the 2014 Long-Term Operations Biological Opinions (LOBO) Annual Science Review

Delta Stewardship Council (Delta Council) | December 1st, 2014

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.

Integrated approaches to understanding and reducing drought impact on food security across scales

Current Opinion in Environmental Sustainability (Elsevier) | October 1st, 2019

Understanding the cross-scale linkages between drought and food security is vital to developing tools to reduce drought impacts and support decision making. This study re

Understanding the cross-scale linkages between drought and food security is vital to developing tools to reduce drought impacts and support decision making. This study reviews how drought hazards transfer to food insecurity through changes in physical processes and socio-environmental systems across a wide range of spatial and temporal scales. We propose a multi-scale, integrated framework leveraging modeling advances (e.g. drought and crop monitoring, water-food-energy nexus, decision making) and increased data availability (e.g. satellite remote sensing, food trade) through the lens of the coupled human–natural system to support multidisciplinary approaches and avoid potential policy spillover effects. We discuss current scale-dependent challenges in tackling drought-induced food security whilst minimizing water use conflicts and environmental impacts. 

Intensification of hydrological drought in California by human water management

American Geophysical Union (AGU) | January 25th, 2017

Interactions between snow cover and evaporation lead to higher sensitivity of streamflow to temperature

Nature Portfolio (Springer Nature) | December 4th, 2020

Estimates of potential evaporation often neglect the effects of snow cover on evaporation process. Here, we present a definition of potential evaporation that explicitly

Estimates of potential evaporation often neglect the effects of snow cover on evaporation process. Here, we present a definition of potential evaporation that explicitly accounts for landscapes that are partially covered by snow. We show that, in the presence of snowpack, our evaporation estimates differ from conventional methods that assume evaporation from a free water surface. Specifically, we find that conventional methods overestimate potential evaporation as well as aridity, taken as the ratio of atmospheric water demand to supply, in landscapes where snowfall is significant. With dwindling snow-cover, actual aridity increases, which could explain the reduction in streamflow with decreasing snowfall. We suggest that streamflow, and hence water availability, is more sensitive to temperature changes in colder than in warmer regions.

Interpreting Water Supply Forecasts

U.S. Bureau of Reclamation (USBR) | January 24th, 2012

For each Central Valley Project (CVP) allocation announcement, two forecasts are issued for each contract type by location within the CVP. Unless otherwise specified, all

For each Central Valley Project (CVP) allocation announcement, two forecasts are issued for each contract type by location within the CVP. Unless otherwise specified, all runoff forecasts are based on runoff volumes that would occur naturally without any upstream influences. For the February through May period, the runoff volume estimates are based on the observed inflow to date and current snow pack measurements made at the end of each preceding month. Water users need to know what the different forecasts represent if they are to use the information appropriately when making operational decisions. Following are explanations of each of the forecasts.

Just the Facts: Land, Water, and Agriculture in the Colorado River Basin

Babbitt Center for Land and Water Policy (Babbitt Center) | March 1st, 2022

Juvenile Production Estimate (JPE) Calculation and Use/Application of Survival Data from Acoustically-tagged Chinook Salmon Releases Report

Delta Stewardship Council (Delta Council) | February 21st, 2014

Each year, NOAA’s National Marine Fisheries Service (NMFS) estimates the number of juvenile winter-run Chinook salmon expected to enter the Delta. NMFS’ June 4, 2009

Each year, NOAA’s National Marine Fisheries Service (NMFS) estimates the number of juvenile winter-run Chinook salmon expected to enter the Delta. NMFS’ June 4, 2009, biological and conference opinion on the long-term operation of the Central Valley Project and State Water Project provides an incidental take limit on natural juvenile winter-run based on the juvenile production estimate.