Bruce McGurk

McGurk Hydrologic

Hydrologic variables such as evapotranspiration (ET) and soil water storage are difficult to observe across spatial scales in complex terrain. Streamflow and lidar-derived snow observations provide information about distributed hydrologic processes such as snowmelt, infiltration, and storage. We use a distributed streamflow dataset across eight bas...

Precipitation data in mountain basins are typically sparse and subject to uncertainty due to difficulties in measurement and capturing spatial variability. Streamflow provides indirect information about basin-mean precipitation, but inferring precipitation from streamflow requires assumptions about hydrologic model structure that influence precipit...

Regions of complex topography and remote wilderness terrain have spatially-varying patterns of temperature and streamflow, but due to inherent difficulties of access, are often very poorly sampled. Here we present a dataset of distributed stream stage, streamflow, stream temperature, barometric pressure, and air temperature from the Tuolumne River...

Given uncertainty in precipitation gauge-based gridded datasets over complex terrain, we use multiple streamflow observations as an additional source of information about precipitation, in order to identify spatial and temporal differences between a gridded precipitation dataset and precipitation inferred from streamflow. In particular, we test whe...

Snow cover and its melt dominate regional climate and water resources in many of the world's mountainous regions. Snowmelt timing and magnitude in mountains are controlled predominantly by absorption of solar radiation and the distribution of snow water equivalent (SWE), and yet both of these are very poorly known even in the best-instrumented moun...

Snow cover and its melt dominate regional climate and water resources in many of the world's mountainous regions. However, we face significant water resource challenges due to the intersection of increasing demand from population growth and changes in runoff total and timing due to climate change. Moreover, increasing temperatures in desert systems...

Removal of stream channel shading during timber harvest operations may raise the stream temper- ature and adversely affect desirable aquatic populations. Field work in California at one clearcut and one mature fir site demonstrated diurnal water temperature cycles and provided data to evaluate two stream temperature prediction techniques. Larger di...

Future streamflow is assessed for the Tuolumne River, a representative watershed in Sierra Nevada Mountains in California that provides 85% of the San Francisco Public Utility Commission's water supply for 2.5 million Bay Area residents and water to 8000 agricultural customers and over 200,000 electrical customers of the Turlock and Modesto Irrigat...

Seasonal snowcover in the Sierra Nevada of California is the primary source of streamflow tributary to the Sacramento-San Joaquin Delta. The blending of strategically placed on-the-ground measurements with broad-coverage satellite and aircraft measurements offers unprecedented estimates of snowpack, soil moisture, vegetation state and energy balanc...

Before Euro-American settlement fire was a common process in the forests of the Lake Tahoe Basin. The combination of drought, fire suppression, and past harvesting has produced ecosystems that are susceptible to high-severity wildfires. Consequently, a program of prescribed fire has been recommended but there is incomplete understanding of the ecol...

The collection of hydrometeorological data is becoming privatized, and competition within the industrial sector (utilities, weather forecasting, etc.) is intensifying. Disruption in collection and distribution of these data will adversely affect both the science community and general public. The problem extends beyond California and the United Stat...

A watershed disturbance index developed by the USDA Forest Service called equivalent roaded area (ERA) was used to assess the cumulative effect from forest management in California's Sierra Nevada and Klamath mountain ranges. The basins' ERA index increased as logging and road-building occurred and then decreased over time as management ceased and...

Past research by the authors has shown that percolating water from either rainfall or surface melt typically flows through the snowpack in vertical channels often referred to as flow fingers. The fingers develop during seasonal metamorphism or in response to rainfall, and between 15% and 25% of a cross-sectional area may transmit water and be near...

Ten pairs of snow sensors were analyzed to investigate the feasibility of predicting snow water equivalent at high-elevation, telemetered snow sensor sites from lower-elevation sensors. The need for this analysis stems from an agreement between the California Department of Water Resources and the USDA Forest Service to temporarily allow snow sensor...

Five east-west strips were harvested in 1962 to test the potential for snow redistribution in California's snow zone. Snow depth and water equivalent data were collected from 1962 through 1964 and again from 1982 through 1984. In both sets of measurements, the average absolute depths and snow water equivalents were generally significantly greater i...

The Soil Conservation Service Curve Number (CN) method is a well-accepted tool in applied hydrology, used for estimating runoff volumes from rainfall events. The guiding light of CN application has been Section 4 of the National Engineering Handbook (NEH-4) which has gone through several revisions. In lieu of any on-site information, the handbook p...

This document summarizes the environmental, health, and safety (EH and S) problems associated with 27 technological areas. A problem summary for each area provides an introduction to some of the major environmental implications and a discussion of major problems identified from the Annual Environmental Analysis Report (AEAR) and the Market Oriented...

The costs of producing silvicultural biomass on intensively managed, short-rotation farms at ten study sites are estimated. Cost estimates are derived by means of a computerized financial model, based on a conceptual production design that identifies the sequence of operations and activities for the farm and the materials and labor required. Site-s...

Land suitability criteria were developed and used to identify potentially available land for silvicultural biomass farms. Six land availability scenarios were chosen for analysis. The annual potential production of biomass energy was estimated on a regional basis assuming the use of 10 percent of the potentially available land in each of the six sc...

Four methods for measuring atmospheric deposition in the Sierra Nevada of California were compared during the winter of 1986-1987. A large (28 by 122-cm) polyvinyl chloride tube was compared to a Belfort precipitation gauge and to snowboards at both an exposed site, near Mammoth Lakes, and a site in a forest clearing, near Soda Springs. An Aerochem...

Since 1982, under an agreement between the California Department of Water Resources and the USDA Forest Service, snow sensors have been installed and operated in Forest Service-administered wilderness areas in the Sierra Nevada of California. Because analysis of snow water equivalent(SWE) data from these wilderness sensors would not be possible unt...

Hydropower facilities typically operate under 30-year licenses from the Federal Energy Regulatory Commission. In the recent licenses that have been obtained by Pacific Gas and Electric Company (Company), a key part of the license is the setting of the minimum streamflow regime in the river reaches that are affected by project facilities such as dam...

Studies have shown that changes in winter air temperature have an effect on snow deposition and runoff patterns in the Sierra Nevada. Hetch Hetchy Reservoir, on the Tuolumne River at 3,806 feet, impounds 459 square miles of Yosemite National Park watershed ranging up to 12,000 ft. Hetch Hetchy Water and Power (HHWP) manages Hetch Hetchy and two oth...