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Research about Phoenix, Arizona

Source-linked reports with geographic coverage including Phoenix, Arizona.

7 recordsLinked to original sources
USGS2021

Extreme precipitation across adjacent burned and unburned watersheds reveals impacts of low severity wildfire on debris-flow processes

In steep landscapes, wildfire-induced changes to soil and vegetation can lead to extreme and hazardous geomorphic responses, including debris flows. The wildfire-induced mechanisms that lead to heightened geomorphic responses, however, depend on many site-specific factors including regional climate, vegetation, soil texture, and soil burn severity. As climate and land use change drive changes in fire regime, there is an increasing need to understand how fire alters geomorphic responses, particularly in areas where fire has been historically infrequent. Here, we examine differences in the initiation, magnitude, and particle-size distribution of debris flows that initiated within the area burned by the 2019 Woodbury Fire in central Arizona, USA, and those that initiated in a nearby unburned area. Despite similar rainfall intensities, unburned watersheds were less likely to produce debris flows. Debris flows in unburned areas initiated from both runoff and shallow landslides, while debris flows only initiated from runoff-related processes in the burned area. The grain-size distribution making up the matrix of debris-flow deposits within the burned area generally had a lower ratio of sand to silt relative to debris flows that initiated in the unburned area, though there were no systematic differences in the coarse fraction of debris-flow sediment between burned and unburned areas. Results help expand our ability to predict postwildfire debris-flow activity in a wider range of settings, specifically the Sonoran Desert ecoregion, and provide general insight into the impact of wildfire on geomorphic processes in steep terrain.

Arizona↗
USGS2008

Does urbanization influence the spatial ecology of Gila monsters in the Sonoran Desert?

To assess whether urbanization influences the spatial ecology of a rare and protected venomous reptilian predator, the Gila monster Heloderma suspectum , we compared home range (HR) size and movement parameters at three sites varying in degree of urbanization in the Sonoran Desert. We predicted that the urban population of H. suspectum would exhibit smaller HRs, avoid human structures and show less movement. Multivariate analysis indicated that males generally exhibited larger HRs and had higher movement rates and activity levels than females at all three sites. Contrary to our predictions, however, HR size and movement parameters did not vary across the sites in relation to the level of urbanization. At the urban site, individuals often crossed narrow roads and regularly used artificial structures as refuges for extended periods. Furthermore, the population sex ratio at the urban site was female-biased, consistent with the expectation that occupation of larger HRs and higher movement rates results in higher mortality for males in urbanized areas. Gila monsters did not appear to alter certain aspects of their spatial ecology in response to low levels of human activity but additional work will be required to assess population viability and possible effects in the long term and with higher levels of urbanization.

Arizona↗
USGS1983

Streamflow losses and changes in ground-water levels along the Salt and Gila Rivers near Phoenix, Arizona — February 1978 to June 1980

From March 1978 to June 1980, high runoff from the Salt and Verde drainage basins combined with large carryover storage in a reservoir system led to the release of about 8.26 million acre-feet of water. About 2.89 million acre-feet of the water was diverted above Granite Reef Dam, and about 5.45 million acre-feet was released into the normally dry channel of the Salt River. The total streamflow losses in the 74-mile reach between Granite Reef and Gillespie Dams were at least 474,000 acre-feet. Most of the water infiltrated into the permeable alluvial deposits along the Sal and Gila Rivers and increased the amount of ground water in storage. From February 1978 to May 1980, ground-water levels in 169 wells that tap the alluvial deposits in the Salt River Valley rose an average of 35.5 feet. The rise in ground-water levels was a direct result of the infiltrating floodwaters and a marked decrease in ground-water pumpage. (USGS)

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