USGS Science⌕ Search

Geology topics

Research about Fresno County, California

Source-linked reports with geographic coverage including Fresno County, California.

5 recordsLinked to original sources
USGS2023

Elevated road segment (ERS) passage design may provide enhanced connectivity for amphibians, reptiles, and small mammals

Introduction: Designs for safe and effective road crossing structures for small animals are typically under-road microtunnels and culverts which have varying levels of effectiveness reported in the scientific literature. Many species, particularly migratory amphibians, may have limited ability to find and use passages if they are too far apart, resulting in substantial barrier effects. Methods: We designed a novel open elevated passage (elevated road segment: ERS), similar to a low terrestrial bridge, that could theoretically be built to any length based upon species needs and movement characteristics. A 30 m length prototype ERS was installed along a forest road with a history of amphibian road mortality in Sierra National Forest, Fresno County, CA, USA. From 2018 to 2021, we monitored small animal activity under the ERS in relation to surrounding roadside and forest habitats using active infrared cameras. Results: We documented a total of 8,815 unique use events, using species specific independence criteria, across 22 species of amphibians (3), reptiles (4), and small mammals (15). Poisson regression modeling of taxonomic group activity under the ERS, roadside and forest, showed that amphibian activity was highest in the forest habitat, no differences were observed for reptiles, and small mammal activity was highest under the ERS. However, mean activity estimates under the ERS were equal to or greater than the open roadside habitat for all 22 species, suggesting that adding cover objects, such as downed logs and vegetation may further enhance passage use. Discussion: Overall, results showed that the design of the ERS crossing has potential to provide high connectivity for a wide range of amphibian, reptile, and small mammal species while reducing road mortality. ERS systems can also be used in areas with challenging terrain and other hydrological and environmental constraints. Incorporating current road ecology science, we provide supplemental ERS concept designs for secondary roads, primary roads and highways to help increase the options available for road mitigation planning for small animals.

California↗
USGS2010

New tritium data on movement of groundwater in western Fresno County, California

Well waters along two traverse lines were sampled in 1963 and tested for tritium concentration. Haskell et al . [1966] estimated from the apparent thermonuclear tritium concentrations that groundwater had moved westward in the lower water‐bearing zone at a maximum velocity of 14–16.5 mi (23–27 km) in 9 yr. The maximum velocities and permeabilities estimated from the 1963 sampling were about an order of magnitude greater than the velocities and permeabilities suggested by prior hydrologic and geologic evidence. Consequently, in 1966–1970 the U.S. Geological Survey sampled and tested the tritium concentrations of well waters along the same two traverses but also extended the sampling eastward. On the basis of these analyses it is concluded that (1) thermonuclear tritium had not invaded the lower zone by 1970 within the extent of the 1963 sampling and (2) although the maximum westward movement of groundwater in the lower zone from 1955 to 1970 is indeterminate, it has been less than 4 mi (6.5 km) from the recharge area in 15 yr.

California↗
USGS1987

Rainfall and runoff quantity and quality characteristics of four urban land-use catchments in Fresno, California, October 1981 to April 1983

Rainfall and runoff quantity and quality were monitored for industrial, single-dwelling residential, multiple-dwelling residential, and commercial land-use catchments in Fresno, California, during 1981-82 and 1982-83 rain seasons. Storm-composite rainfall and discrete runoff samples were analyzed for physical, inorganic, organic, and biological constituents. Atmospheric dry-deposition- and street-surface particulate samples also were collected and analyzed. Except for the industrial catchment, highest runoff concentrations for most constituents occurred during initial storm runoff and then decreased throughout the remainder of the storm; constituent concentrations for the industrial catchment fluctuated greatly. Statistical testing of runoff-quality data showed higher concentration for most constituents for the industrial catchment. Lead showed lower concentrations for the industrial catchment than for the other three catchments. Event mean concentration (EMC) for most constituents for all but the industrial catchment were highest for the first two or three storms of the rain season after which they became almost constant; the industrial constituent EMC 's generally did not show any pattern. The organophosphorus compounds, parathion, diazinon, and malathion were the most prevalent pesticides detected in rainfall. Other pesticides detected in rainfall included chlordane, lindane, methoxychlor, endosulfan, and 2 ,4-D. Of these, only methoxychlor and endosulfan were not consistently detected in the runoff. (USGS)

California↗
USGS1966

Appraisal of near-surface subsidence on the Panoche Creek fan, Fresno County, California

Near-surface subsidence results chiefly from the compaction of deposits by an overburden load as the clay bond supporting the deposits is weakened by water percolating through the deposits for the first time since burial. About 100 square miles of alluvial-fan deposits in western Fresno County, California, have been affected by manmade near-surface subsidence within the past few decades. Subsidence of 3-5 feet is common and 10-15 feet of subsidence has occurred within small areas. Oren cracks form between areas undergoing different amounts of settlement, and are a characteristic feature of compaction due to wetting. Differential settlement occurring within short distances has destroyed or damaged ditches, canals, roads, pipelines, electric-transmission towers, and buildings, and has made the irrigation of crops difficult. The areas of known near-surface subsidence along the alinement of the San Luis Canal-California Aqueduct were compacted by ponding before construction of the canal. The 11 miles of canal alinement that cross the fan of Panoche Creek were not ponded before construction. ,Although a few reports of local residents to the California Department of Water Resources indicated that some very small areas of settlement had occurred after irrigation, it was generally considered that the fan would not be susceptible to widespread near-surface subsidence. The irrigated fields did not show the pronounced hummocky relief and subsidence hollows that were typical of the areas of known near-surface subsidence. Nit as strong was the evidence from core holes that showed that the deposits, even in areas that had never been irrigated, were roughly at field capacity instead of being moisture deficient. This seemed logical because Panoche Creek had been observed to flow for 1-5 months during years of heavy rainfall, in contrast to the ephemeral flow of streams on the Moreno Gulch fan to the northwest and on the Tumey Gulch fan to the south. It was assumed that if similar flows had occurred in the past, the deposits would have been wetted thoroughly from the land surface to the water table with each major period of flow and deposition.

California↗