Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms.
Recent Conditions
The instruments for this site were installed in the spring of 2009 and are used to monitor and detect changes in local conditions. Soil water content and ground water pressure are monitored at two nests on the same hillslope. Data for the site include:
- Rainfall
- Upper Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Lower Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Air Temperature, Relative Humidity, and Battery Voltage
Data are recorded every 5 minutes and updated on the graph every 30 minutes.
Project Background
Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms. Both shallow (<3 meter) and deep (≥3 meter) landslides can occur. Typically, shallow landslides occur as a result of high-intensity precipitation when the ground is already nearly saturated with water from previous storms. These types of events can occur during the height of the rainy season, from December through February. Deep-seated landslides can also occur during these times, but are also often triggered during the spring months (March through May), when water from rainfall has had a chance to make its way to deeper soil and bedrock.
The U.S. Geological Survey, in cooperation with local and state government organizations, operates several shallow landslide monitoring sites in the SFBA for research purposes. The goal of this research is to identify thresholds for widespread shallow landsliding and related high-mobility debris flows based on in-situ soil moisture conditions. This information is being used to develop landslide warning criteria with the National Weather Service. Monitoring data includes cumulative rainfall, rainfall intensity, soil water content, groundwater pressure, air temperature, and relative humidity. Infiltration of water from rainfall increases soil water content, cumulatively saturating the soil profile. However, periods without rainfall can lead to drying of the soil. If the soil profile is nearly saturated, additional intense precipitation can increase groundwater pressures which can, in turn, induce landslide movement.
Below are other science projects associated with this project.
Rainfall and Landslides in Northern California
Below are publications associated with this project.
Identifying physics‐based thresholds for rainfall‐induced landsliding
Variability in soil-water retention properties and implications for physics-based simulation of landslide early warning criteria
Monitoring subsurface hydrologic response for precipitation-induced shallow landsliding in the San Francisco Bay area, California, USA
- Overview
Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms.
Recent Conditions
The instruments for this site were installed in the spring of 2009 and are used to monitor and detect changes in local conditions. Soil water content and ground water pressure are monitored at two nests on the same hillslope. Data for the site include:
- Rainfall
- Upper Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Lower Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Air Temperature, Relative Humidity, and Battery Voltage
Data are recorded every 5 minutes and updated on the graph every 30 minutes.
Project Background
Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms. Both shallow (<3 meter) and deep (≥3 meter) landslides can occur. Typically, shallow landslides occur as a result of high-intensity precipitation when the ground is already nearly saturated with water from previous storms. These types of events can occur during the height of the rainy season, from December through February. Deep-seated landslides can also occur during these times, but are also often triggered during the spring months (March through May), when water from rainfall has had a chance to make its way to deeper soil and bedrock.
The U.S. Geological Survey, in cooperation with local and state government organizations, operates several shallow landslide monitoring sites in the SFBA for research purposes. The goal of this research is to identify thresholds for widespread shallow landsliding and related high-mobility debris flows based on in-situ soil moisture conditions. This information is being used to develop landslide warning criteria with the National Weather Service. Monitoring data includes cumulative rainfall, rainfall intensity, soil water content, groundwater pressure, air temperature, and relative humidity. Infiltration of water from rainfall increases soil water content, cumulatively saturating the soil profile. However, periods without rainfall can lead to drying of the soil. If the soil profile is nearly saturated, additional intense precipitation can increase groundwater pressures which can, in turn, induce landslide movement.
The USGS “BALT1” site is located in the San Francisco East Bay and consists of a cattle-protected enclosure with dataloggers monitoring the hillslope in the central part of the image. This slope is typical for many in the East Bay region that have generated mobile debris flows in the past. The area consists of grasslands over an approximately 1-meter-deep sandy soil layer, underlain by sandstone. (Public domain.) The USGS “BALT1” monitoring site showing datalogger enclosure, solar panel, air temperature sensor, and rainfall gage. The contents are contained within a fence enclosure to protect the instrumentation from grazing cattle. (Public domain.) - Science
Below are other science projects associated with this project.
Rainfall and Landslides in Northern California
A summary of recent and past landslides and debris flows caused by rainfall in northern California, and links to current shallow landslide monitoring. - Publications
Below are publications associated with this project.
Identifying physics‐based thresholds for rainfall‐induced landsliding
Most regional landslide warning systems utilize empirically derived rainfall thresholds that are difficult to improve without recalibration to additional landslide events. To address this limitation, we explored the use of synthetic rainfall to generate thousands of possible storm patterns and coupled them with a physics‐based hydrology and slope stability model for various antecedent soil saturatVariability in soil-water retention properties and implications for physics-based simulation of landslide early warning criteria
Rainfall-induced shallow landsliding is a persistent hazard to human life and property. Despite the observed connection between infiltration through the unsaturated zone and shallow landslide initiation, there is considerable uncertainty in how estimates of unsaturated soil-water retention properties affect slope stability assessment. This source of uncertainty is critical to evaluating the utilitMonitoring subsurface hydrologic response for precipitation-induced shallow landsliding in the San Francisco Bay area, California, USA
Intense winter storms in the San Francisco Bay area (SFBA) of California, USA often trigger shallow landslides. Some of these landslides mobilize into potentially hazardous debris flows. A growing body of research indicates that rainfall intensity-duration thresholds are insufficient for accurate prediction of landslide occurrence. In response, we have begun long-term monitoring of the hydrologic