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Geochemists have long recognized a correlation between rates of physical denudation and chemical weathering. What underlies this correlation? The Critical Zone can be considered as a feed-through reactor. Downward advance of the weathering front brings unweathered rock into the reactor. Fluids are supplied through precipitation. The reactor is stirred at the top by biological and physical processes. The balance between advance of the weathering front by mechanical and chemical processes and mass loss by denudation fixes the thickness of the Critical Zone reactor. The internal structure of this reactor is controlled by physical processes that create surface area, determine flow paths, and set the residence time of...
Hillslopes have been intensively studied by both geomorphologists and soil scientists. Whereas geomorphologists have focused on the physical soil production and transport on hillslopes, soil scientists have been concerned with the topographic variation of soil geochemical properties. We combined these differing approaches and quantified soil chemical weathering rates along a grass covered hillslope in Coastal California. The hillslope is comprised of both erosional and depositional sections. In the upper eroding section, soil production is balanced by physical erosion and chemical weathering. The hillslope then transitions to a depositional slope where soil accumulates due to a historical reduction of channel incision...
The purpose of the Conservation Effects Assessment Project (CEAP) cropland national assessment is to quantify the environmental benefits of conservation programs at the regional and national levels, which include both onsite and instream water quality benefits. Modeling is an effective tool for environmental assessment at the regional and national scale due to the complexities in nature at this scale. Two simulation models, the Agricultural Policy Environmental extender (APEX) and the Soil and Water Assessment Tool (SWAT), were used for the CEAP cropland national assessment. A subset of National Resources Inventory (NRI) sample points was selected to serve as "representative fields" for the CEAP cropland survey...
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This file represents the final version of an assessment of the extent, condition, and distribution of grassland types in Arizona as indicated by expert interviews and field verification. Coverage includes the state of Arizona, Southwestern portions of the state of New Mexico, and the Northern portion of Sonora, Mexico.
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The Desert Renewable Energy Conservation Plan (DRECP), a major component of California's renewable energy planning efforts, will help provide effective protection and conservation of desert ecosystems while allowing for the appropriate development of renewable energy projects. The DRECP is focused on the desert regions and adjacent lands of seven California counties - Imperial, Inyo, Kern, Los Angeles, Riverside, San Bernardino, and San Diego. It is being prepared through an unprecedented collaborative effort between the California Energy Commission, California Department of Fish and Wildlife, the U.S. Bureau of Land Management, and the U.S. Fish and Wildlife Service also known as the Renewable Energy Action Team....
Effects of the northern pocket gopher (Thomomys talpoides) on surface soilcharacteristics were examined at the alpinesite of Niwot Ridge, CO. We measured erosionof soil from gopher mounds and compared thecharacteristics of gopher mound (disturbed) andundisturbed soils in two major plant communitytypes. Our measurements of erosion indicatelong-term susceptibility of gopher-disturbedsoils to redistribution by water and/or wind inthis ecosystem. Ecosystem heterogeneityintroduced by the gopher is reflected insignificantly lower SOM in gopher mounds thanin surrounding undisturbed soils, acharacteristic which appears to be causallyassociated with other effects of gopherdisturbance including changes in soil textureand...
Modern short term sediment yields, averaged for geomorphic surfaces (mesa, steep colluvial slopes, gently sloping hillslopes, and the alluvial valley floor) with sediment traps and straw dams range from 0.2 to 1.8 kg.m-2. yr-1 and exceed long term sediment yield of 0.27 kg.m-2. yr-1 (10Be-based) in a heavily studied semi-arid drainage basin. The differences between sediment production and yield were most noticeable for the alluvial valley floor, where individual sediment traps and dams ranged up to 3.3 kg.m-2. yr-1. The alluvial valley floor is grazed and has a gas pipeline running through it; thus, the sediment yields on the alluvial valley floor likely represent human influence. Sediment yield in contributing...
Water erosion results in the mobilization and depletion of soil organic carbon (SOC), but studies providing direct experimental evidence of eroded C mineralization and its linkage to the global C cycle are lacking. A study was conducted to determine the mineralization of SOC in runoff from a southwestern Ohio Crosby soil (fine, mixed, mesic Aeric Ochraqualf) that had been under no-till (NT), chisel till (CT) and moldboard plow (MP) for 38 years. To simulate present and future soil erosion conditions, the 0–3 and 5–8 cm soil layers from triplicate soil blocks extracted from each tillage practice were used. Soil layers were transferred to runoff trays and simulated rainfall (30±5 mm h−1) was applied for 1 h. Runoff...
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Synopsis: Wind erosion control is typically needed in areas with low and variable precipitation and frequent droughts, and where high winds, high temperature and consequent high evaporation are common conditions, such as in southern Alberta. Potential average annual erosion rates from wind erosion are predicted using the wind erosion equation E= f(I, K, C, L, V) where I is the soil erodibility index, K is the soil-ridge-roughness factor, C is the climactic factor, L is the unsheltered, weighted travel distance of the wind across a field and V is the equivalent vegetated cover. Wind erosion can be controlled with one or more of the following five basic principles of wind erosion control: · Reduce field widths...
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Web Soil Survey (WSS) provides soil data and information produced by the National Cooperative Soil Survey. It is operated by the USDA Natural Resources Conservation Service (NRCS) and provides access to the largest natural resource information system in the world. NRCS has soil maps and data available online for more than 95 percent of the nation’s counties and anticipates having 100 percent in the near future. The site is updated and maintained online as the single authoritative source of soil survey information. Soil surveys can be used for general farm, local, and wider area planning. Onsite investigation is needed in some cases, such as soil quality assessments and certain conservation and engineering applications....
Restoration of ecological processes is key to restoring the capacity of ecosystems to support social, economic, cultural and aesthetic values. The sustainability of the restored system also depends on processes associated with carbon, nutrient and hydrologic cycles, yet most restoration monitoring is limited to plant community composition. Our research has shown that short-term plant composition monitoring is a necessary but insufficient predictor of long-term restoration success. Long-term (up to 75 years) studies in the western United States show that short-term monitoring of plant community composition alone incorrectly predicted the failure of treatments that were ultimately successful, and the success of treatments...
Geostatistical analyses show that the distribution of soil N, P and K is strongly associated with the presence of shrubs in desert habitats. Shrubs concentrate the biogeochemical cycle of these elements in ?islands of fertility? that are localized beneath their canopies, while adjacent barren, intershrub spaces are comparatively devoid of biotic activity. Both physical and biological processes are involved in the formation of shrub islands. Losses of semiarid grassland in favor of invading shrubs initiate these changes in the distribution of soil nutrients, which may promote the further invasion and persistence of shrubs and cause potential feedbacks between desertification and the Earth's climate system. Published...
Soil organic carbon (SOC) is a biophysical parameter, which is also directly linked to above ground land use and land cover (LULC). Currently changes in LULC and variations in SOC often are studied and modeled separately. However, both are conjoined and should be seen as part of a cascading ecosystem framework. This is not only true for SOC but also for other biophysical parameters which are governed by human activities. At a watershed scale, this relationship is exceptionally important and the focus should be towards studying the impact of LULC change on the levels of SOC in spatially explicit terms. To advance knowledge on this front, we studied transformations of LULC, erosion and SOC from the start of settled...
Land use land cover (LULC) plays an important role in influencing the spatial intensity of water erosion which is the primary governor of horizontal translocation of soil organic carbon (SOC). The fate of redistributed SOC through erosion remains debatable and the mineralization rate of exposed SOC protected in soil aggregates is the major focus of this argument. Cohesive spatially explicit modeling of SOC and erosion can potentially reduce some of the controversy. To this end we simulated erosion/deposition, and photosynthetic (in situ) flux of SOC in a small watershed of ~ 28.42 ha, located in the Big Creek basin of southern Illinois. The main objectives of this research were: (a) to study erosion and deposition...
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Grasslands of the Sky Islands region once covered over 13 million acres in southeastern Arizona and adjacent portions of New Mexico, Sonora, and Chihuahua. Attempts to evaluate current ecological conditions suggest that approximately two thirds of these remain as intact or restorable grassland habitat. These grasslands provide watershed services such as flood control and aquifer recharge across the region, and continue to support dozens of species of concern. Prioritizing conservation interventions for these remaining grassland blocks has been challenging. Reliable data on condition and conservation value of grasslands in the region have not been systematically summarized. State and national boundaries further complicate...
Abstract (from http://link.springer.com/article/10.1007%2Fs11069-015-1698-6): Chronic erosion in Hawaiʻi causes beach loss, damages homes and infrastructure, and endangers critical habitat. These problems will likely worsen with increased sea level rise (SLR). We forecast future coastal change by combining historical shoreline trends with projected accelerations in SLR ( IPCC RCP8.5) using the Davidson-Arnott profile model. The resulting erosion hazard zones are overlain on aerial photos and other GIS layers to provide a tool for identifying assets exposed to future coastal erosion. We estimate rates and distances of shoreline change for ten study sites across the Hawaiian Islands. Excluding one beach (Kailua) historically...
The definition of desertification accepted in the ad hoc conference held by UNEP in Nairobi in 1977 and confirmed at the Earth Summit on Environment and Development held in Rio de Janeiro in 1992 is: ?arid, semi-arid and dry-subhumid land degradation?. There is no global long-term trend in any rainfall change over the period of instrumental record (c. 150 years), but there has been an increase of 0�5�C in global temperature over the past 100 years. This increase seems partly due to urbanization, as there is no evidence of it resulting from atmospheric pollution by CO2and other warming gases (SO2, NO2, CH4, CFH etc.). On the other hand, the thermal increase is uneven, increasing with latitudes above 40� N and S....
Soil surface roughness may significantly impact runoff and erosion under rainfall. A common perception is that runoff and erosion are decreased as a function of roughness because of surface ponding and increased hydraulic roughness that reduces effective flow shear stress. The objective of this study was to measure the effects of initial surface roughness on runoff and erosion under controlled laboratory conditions. Initially, rough and smooth surfaces were exposed to five simulated rainfall applications at 5% and 20% slopes. In all cases, runoff was delayed for the case of the initially rough surface; however, this effect was temporary. Overall, no statistical differences in either total runoff or erosion were...
Aeolian erosion of natural dust on two types of hills located in a rocky desert was investigated by means of wind tunnel simulations and field measurements. The first hill showed an elongated, nearly symmetric shape and was oriented perpendicular to the wind, whereas the second hill was almost perfectly conical. Erosion was measured along three transects: one across the elongated hill (transect parallel to the wind) and two across the conical hill (transects perpendicular to each other and crossing at the summit). In the field, erosion was measured on erosion plots during two wind storms. In the wind tunnel, erosion was measured on topographic scale models. The wind tunnel experiments and field experiments showed...
The ability to predict the effects of dam removal in highly sediment-filled systems is increasingly important as the number of such dam removal cases continues to grow. The cost and potential impacts of dam removal are site-specific and can vary substantially depending on local conditions. Of specific concern in sediment-impacted removals is the volume and rate of reservoir deposit erosion. The complexity and potential accuracy of modeling methods used to forecast the effects of such dam removals vary substantially. Current methods range from predictions based on simple analysis of pre-dam channel geometry to sophisticated data-intensive, three-dimensional numerical models. In the work presented here, we utilize...
map background search result map search result map Basic principles of wind erosion control Desert Renewable Energy Conservation Plan Extent and Condition of Grasslands in Arizona, Northern Mexico, and Southwestern New Mexico Web Soil Survey Sustaining the Grassland Sea Sustaining the Grassland Sea Desert Renewable Energy Conservation Plan Extent and Condition of Grasslands in Arizona, Northern Mexico, and Southwestern New Mexico Basic principles of wind erosion control Web Soil Survey