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Langbein and Schumm (1958) connected precipitation to erosion in a right-skewed curve used in earth science textbooks for over six decades, where denudation increases with precipitation on the arid/semiarid limb and decreases in humid regions. Development of the catchment-averaged 10Be denudation method a quarter-century ago led geomorphologists to evaluate this hypothesis using data not influenced by the Anthropocene, with mixed findings. The Sonoran Desert in Arizona, USA, is optimal for investigating the longstanding hypothesis of increased erosion from arid to semiarid climates due to: (i) the modern orographic effect aligning elevated precipitation with altitude, mirroring Neotoma packrat midden paleoecology research for the Holocene and late Pleistocene; (ii) the region has been tectonically quiet for the residence times of analyzed 10Be ranging from ca. 8,000-110,000 years. Our significant finding echoes Langbein and Schumm's work, revealing heightened erosion along an elevation-precipitation gradient from arid to semiarid conditions. Notably, the significance of precipitation-elevation contrasts with the absence of significant correlation between 10Be denudation and attributes like slope, drainage area, relief, or landform type (e.g., alluvial fan, pediment, mountain watershed). Modern faunalturbation, increasing along this gradient, exposes more ground to rainsplash and overland flow at higher elevations, adding complexity to these results. Further insights unveil that (i) catchments in areas with substantial Quaternary base level reduction imitate tectonic effects, tripling 10Be denudation rates; (ii) basaltic boulders and cobbles yield an armoring influence; (iii) historical erosion acceleration due to urbanization and wildfires insignificantly affects 10Be denudation rates in the Sonoran Desert; and (iv) minute desert catchments yield anomalous erosion rates. [ABSTRACT FROM AUTHOR]

Land use changes often lead to soil erosion, land degradation, and environmental deterioration. However, little is known about just how much humans accelerate erosion compared to natural background rates in non-agricultural settings, despite its importance to knowing the magnitude of soil degradation. The lack of understanding of anthropogenic acceleration is especially true for arid regions. Thus, we used 10Be catchment averaged denudation rates (CADRs) to obtain natural rates of soil erosion in and around the Phoenix metropolitan region, Arizona, United States. We then measured the acceleration of soil erosion by grazing, wildfire, and urban construction by comparing CADRs to erosion rates for the same watersheds, finding that: (i) grazing sometimes can increase sediment yields by up to 2.3-2.6x, (ii) human-set wildfires increased sediment yields by up to 9.7-10.4x, (iii) after some post-fire vegetation recovered, sediment yield was then up to 4.2-4.5x the background yield, (iv) construction increased sediment yields by up to 5.0-5.6x, and (v) the sealing of urban surfaces led to one-tenth to one-half of the background sediment yields. The acceleration of erosion at the urban--rural interface in arid lands highlights the need for sustainable management of arid-region soils. [ABSTRACT FROM AUTHOR]

Cattle stock ponds on the fringe of metropolitan Phoenix, USA, experienced a wide range of land‐use changes over the period from 1989 to 2009. This research measures soil erosion from watersheds of different rock types, variable relief, and land uses. Monitoring sediment accumulation behind 18 earthen berms at each major land‐use transition enabled calculations of soil erosion rates. Compared with the first decade of study with more precipitation and cattle grazing, accelerated urbanization in the drier second decade increased soil erosion from wildfires by up to 4.2×, from exposure of bare ground due to building construction by up to 3.4×, and from bare ground exposure due to road and pipeline construction by up to 3.1× overgrazing alone. Stock pond watersheds underlain by granite experienced statistically significant higher erosion rates compared with watersheds underlain by metamorphic, basalt, and other rock types. Global sediment yield data for warm desert (BWh Köppen‐Geiger) sites reveal that our data plot consistently with other grazed study areas with a tendency for higher area‐specific sediment yields in smaller drainage areas. These sediment yield data, however, do not support previously published generalizations of anomalously high or low sediment yields from warm desert settings. Desert urbanization processes accelerate soil erosion, resulting in the need for regulatory agencies to impose new erosion mitigation strategies. [ABSTRACT FROM AUTHOR]