Modeling the impact of future rainfall changes on the effectiveness of urban stormwater control measures

Springer Nature | February 19th, 2024

The convergence of urban expansion, deteriorating infrastructure, and a changing climate will escalate the risks of stormwater pollution and urban flooding in the coming

The convergence of urban expansion, deteriorating infrastructure, and a changing climate will escalate the risks of stormwater pollution and urban flooding in the coming decades. Using outputs from an ensemble of global climate models to drive a high spatial resolution stormwater model, we analyzed climate change impacts on urban stormwater runoff and control measures for 23 cities across the United States. Runoff model outputs for two future emissions scenarios ending in 2055 were compared against a historical scenario to assess changes. All cities showed increases in average annual stormwater runoff, with changes up to 30% over the next 30 years due to a greater frequency of high intensity storm events. Runoff model outputs showed substantial variation across cities with untreated stormwater runoff increasing by as much as 48%. Patterns of future runoff impacts within cities will affect the performance of distributed treatment strategies such as Green Stormwater Infrastructure (GSI) to meet municipal water quality improvement and runoff reduction goals. Results indicate that adoption of adaptable design standards and decision support tools that readily accommodate projected precipitation changes are critical for supporting more resilient designs of stormwater control measures.

Moisture vs. Wind-Dominated Flavors of Atmospheric Rivers

American Geophysical Union (AGU) | November 20th, 2020

Atmospheric rivers (ARs) are essential features of the global water cycle. Although AR definitions are commonly based on integrated vapor transport (IVT), ARs of a given

Atmospheric rivers (ARs) are essential features of the global water cycle. Although AR definitions are commonly based on integrated vapor transport (IVT), ARs of a given IVT can induce a wide range of surface precipitation and wind impacts. We develop an AR “flavor” metric that partitions AR IVT into moisture-dominant and wind-dominant components. We use this metric to create a climatological catalog of “wet” and “windy” ARs along the U.S. West Coast from 1980 to 2016. Windy ARs are generally associated with stronger surface winds than are wet ARs, with the largest differences at low IVT. Windy ARs are also associated with greater daily precipitation totals than are wet ARs, with the difference widening at higher IVT, notably over mountainous regions. Pacific Northwest ARs have become increasingly moisture dominated over 1980–2016, which has important implications for western U.S. water availability and flood risk.

More extreme precipitation in the world's dry and wet regions

Nature Portfolio (Springer Nature) | March 7th, 2016

Intensification of the hydrological cycle is expected to accompany a warming climate. It has been suggested that changes in the spatial distribution of precipitation will

Intensification of the hydrological cycle is expected to accompany a warming climate. It has been suggested that changes in the spatial distribution of precipitation will amplify differences between dry and wet regions, but this has been disputed for changes over land. Furthermore, precipitation changes may differ not only between regions but also between different aspects of precipitation, such as totals and extremes. Here we investigate changes in these two aspects in the world’s dry and wet regions using observations and global climate models. Despite uncertainties in total precipitation changes, extreme daily precipitation averaged over both dry and wet regimes shows robust increases in both observations and climate models over the past six decades. Climate projections for the rest of the century show continued intensification of daily precipitation extremes. Increases in total and extreme precipitation in dry regions are linearly related to the model-specific global temperature change, so that the spread in projected global warming partly explains the spread in precipitation intensification in these regions by the late twenty-first century. This intensification has implications for the risk of flooding as the climate warms, particularly for the world’s dry regions.

Multi-sensor remote sensing captures geometry and slow-to-fast sliding transition of the 2017 Mud Creek landslide

Nature Portfolio (Springer Nature) | August 14th, 2025

Click here for the USGS California Science Center page about the Mud Creek landslide

Click here for the USGS California Science Center page about the Mud Creek landslide

National-Scale Flood Hazard Data Unfit for Urban Risk Management

American Geophysical Union (AGU) | July 19th, 2024

Natural Hazard Mitigation Saves Interim Report

Federal Emergency Management Agency (FEMA) | June 30th, 2018

Natural infrastructure in sustaining global urban freshwater ecosystem services

Nature Portfolio (Springer Nature) | October 21st, 2021

Rapid urbanization throughout the globe increases demand for fresh water and the ecosystem services associated with it. This need is conventionally met through the constr

Rapid urbanization throughout the globe increases demand for fresh water and the ecosystem services associated with it. This need is conventionally met through the construction of infrastructure. Natural infrastructure solutions have increased to provide freshwater ecosystem services, but little global research has examined the intricate relationships between built and natural infrastructure for providing freshwater ecosystem services to cities across the globe. Using network analysis, here we examine the interrelationships between built and natural infrastructure in 2,113 watersheds for 317 cities worldwide, focusing on four key freshwater ecosystem services: freshwater provision, sediment regulation, flood mitigation and hydropower production. Our results indicate that protected wetlands contribute to sustaining freshwater provision to cities. Forest cover in protected areas can improve the capacity of large dams in reducing sediment loads and producing hydropower, but cities mainly depend on reduced impervious surfaces and more green spaces within urban areas for flood mitigation. Improved understandings of the role of natural infrastructure in urban water networks must underpin strategic decision-making to sustainably provide freshwater ecosystem services to global cities.

Nature-based solutions extend the lifespan of a regional levee system under climate change

Nature Portfolio (Springer Nature) | May 9th, 2025

Navigating a Flood of Information Evaluating and Integrating Climate Science into Groundwater Planning in California

Union of Concerned Scientists | November 1st, 2017

In early 2017, northern California experienced record-setting levels of precipitation. The amount of rain and snow from October 2016 through February 2017 was the greates

In early 2017, northern California experienced record-setting levels of precipitation. The amount of rain and snow from October 2016 through February 2017 was the greatest in the 122 years of California record-keeping. As the reservoir behind Oroville Dam quickly filled to capacity, a torrent of excess water was let out through the main spillway. Shortly thereafter the spillway began to collapse, leading to massive soil erosion and concerns that the erosion could undermine the dam itself. Fears of a catastrophic dam breach led to the evacuation of around 180,000 residents downstream from the dam. While we do not know how much climate change contributed to this particular event, we do know that climate change is making extreme events more common (Black et al. 2016; Mote et al. 2016; Otto 2016). While reports indicate that management failures may have played in an important role in the Oroville disaster, it is also true that this event took place in the context of extreme weather, and that climate change is increasing pressure on structures and communities. This finding is not limited to highprofile infrastructure such as the Oroville Dam. Much of our water infrastructure, management tools, institutions, and planning mechanisms are not designed for the increased magnitude and frequency of such extremes—making the state, its environment, and its water resources vulnerable to the changes we are likely to see in the coming decades. In California, groundwater contributes more than half of the state’s water supply during dry years (DWR 2009). Therefore, understanding the impacts that climate change will have on this critical resource will be of particular importance for the state’s water and food security over the long term. To that end, Governor Jerry Brown issued Executive Order B-30-15 that, along with setting ambitious greenhouse gas reduction targets, requires state agencies take climate change into account in their planning and investment decisions. In addition, California’s Sustainable Groundwater Management Act (SGMA), passed by the legislature in 2014, requires that Groundwater Sustainability Agencies (GSAs) explicitly assess the impacts of climate change and incorporate these assessments into their Groundwater Sustainability Plans (GSPs). Under the legislation, GSAs must develop and implement GSPs to achieve sustainable groundwater management in all high- and medium-priority groundwater basins in the state. Within these plans, GSAs are required to provide “[p]rojected water budget information for population, population growth, climate change, and sea level rise” (CWR 354.18(d)(3)). Additionally, projected water budgets must “identify the uncertainties of these projected water budget components,” including uncertainties in projected hydrology, water demand, and surface water supply resulting from sea level rise, land use changes, population growth, and climate change (CWR 354.18(c)(3)). To meet these regulatory requirements, plans must “rely on the best available information and best available science to quantify the water budget for the basin” (CWR 354.18(e)). Yet, it can be difficult to identify the best approach to incorporating climate change into local plans. The purpose of this white paper is to assist in that challenging task. The consequences of not incorporating climate change into water planning can be severe, leading to unforeseen costs and even threatening lives. It is therefore the intention of this white paper to: • provide water managers and other decision-makers across the state with an overview of climate models, their component parts, and key terminology • provide a framework for evaluating and comparing the various approaches currently employed by the state and federal agencies to incorporating climate change into state-level water planning documents • recommend a four-step process to incorporate future climate projections into local GSPs Recognizing the importance of climate change impacts on the state’s water supply, the California Department of Water Resources (DWR) has devoted a significant amount of time and expertise to integrating climate change into water planning. In 2012, DWR convened the Climate Change Technical Advisory Group (DWR CCTAG) to advise DWR on the scientific aspects of climate change, the impact of climate change on water resources, the use and creation of planning approaches and analytical tools, and the development of adaptation responses. The DWR CCTAG released a report in 2015, Perspectives and Guidance for Climate Change Analysis, which makes several recommendations for future work. One central theme is the need to develop guidance and support for water managers and planners. Factoring climate change into water management decisions requires future projections of how climate change will impact water-relevant factors such as temperature and precipitation—projections that are generally derived from global climate models. However, incorporating climate change into water planning for any given community or groundwater basin can be difficult, not only because of the technical expertise required to do so, but also because the effects of climate change are spatially and temporally variable. Although the scientific community has high confidence in a key set of variables for the planet as a whole, translating global estimates of climate change to specific geographical areas creates uncertainty. Fortunately, there are tools and methods to address uncertainty. As is the case for other natural phenomena that are difficult to predict with precision, such as earthquakes, uncertainty cannot be an excuse for inaction. Scientific and technical tools can substantially assist in creating plans that cope with an uncertain future. This white paper does not directly address the role of hydrologic models themselves, but rather addresses how climate change information can be incorporated into hydrologic models as water managers seek to comply with the requirements of SGMA. The process of incorporating climate change into water management decisions has several steps, starting with running global climate models to produce future climate projections, which are then used as inputs to hydrologic models (Figure 1). We recognize that GSAs are likely to engage at different levels of technical sophistication with climate data and that the majority will seek out the services of technical experts. Ultimately, it is our intent that this white paper equip water managers with sufficient knowledge about climate change projections to understand, evaluate, and direct the work of the technical experts and consultants. Using appropriate climate change information is vital to ensuring that water managers capture potential future water resource conditions. This white paper is organized into three main sections. The first section provides a general overview of climate models, including their strengths and limitations and the type of information they can provide, and describes a framework for incorporating their output into management decisions. The second section addresses how to incorporate climate change into planning involving imported water supplies. The third section turns to planning for local water supplies and proposes a process for incorporating appropriate climate change data into GSPs.

New Life for Eroding Shorelines: Beach and Marsh Edge Change in the San Francisco Estuary

San Francisco Estuary Institute (SFEI) | April 1st, 2020

Wind, waves, storms, and changing water levels have reshaped shorelines for millennia and continue to do so today. The current shape of the San Francisco (SF) Estuary sho

Wind, waves, storms, and changing water levels have reshaped shorelines for millennia and continue to do so today. The current shape of the San Francisco (SF) Estuary shoreline is relatively new; 15,000 years ago, the California shoreline was west of the Farallon Islands and 140 meters below its current level (Cohen and Laws 1992, Malamud-Roam et al. 2007). By approximately 6,000 years ago (the end of the last glacial epoch), the sea had risen to nearly its present level and filled what is now San Francisco Bay, allowing marshes to form and maintain themselves (Atwater 1979). More recently, humans have changed the shape of the shoreline. During the 1850s, many marshes expanded extensively due to increased sediment supply from hydraulic mining in the Sierra Nevada (Gilbert 1917, Goals Project 1999). Diking, dredging, and filling of marshes for agricultural and urban development began in the late 19th century and continued through the first half of the 20th century.  Today, humans continue to reshape the shoreline through continued diking, dredging and filling as well as restoration projects, urbanization of watersheds, ferry wakes, and many other means. The most wide-ranging impact of human activity on the shape of shorelines is global climate change caused by greenhouse gas emissions, which is accelerating the rate of sea level rise worldwide (OPC 2018). Sea level rise is likely to cause much more dramatic changes in the shape of shorelines than have been seen in recent centuries. The magnitude and pace of change will depend on the rate of sea level rise, existing shoreline conditions, and the ability of shorelines to adapt.