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From Climate Change to Migration: The Prospects in Iran
Published in Moonisa Aslam Dervash, Akhlaq Amin Wani, Climate Change Alleviation for Sustainable Progression, 2022
Both experiences and scientific studies prove the correlation between climate change and extreme events. Due to the frequency of heavy rainfalls and heat waves, areas affected by drought and tropical cyclone activity have increased (Bouwer, 2011; Mendelsohn and Saher, 2011). In such an atmosphere, the prediction is vulnerable; maybe, as we saw in 2019, a sudden flood, untimely rains or frosts would disrupt all the delightful forecasts! Or, as we are gazing at Lake Urmia, most farms would be poisoned by salt as a result of a dry lake. Locust invasion is a new, yet widespread threat for the southern and south-eastern provinces which lead to FAO's concern (FAO, 2020A). All of these unpleasant events can change calculations.
Desert, Desertification and Land Degradation
Published in Ajai, Rimjhim Bhatnagar, Desertification and Land Degradation, 2022
Desert areas often experience intense infrequent rainfall. Water erosion leads to the formation of erosional and depositional landforms, and erosional features such as sheet, rill and gully formations are quite common in desert areas (details given in Chapter 4). Following intermittent but intense rainfall, low-lying areas in deserts get filled with water. Such short-term lakes are called Playa lakes. They are shallow, often saline and short-lived, lasting from a few hours to several months. Once, their water evaporates, the dry lake bed is termed playa. Another feature is formed when sediment-laden streams flow down the steep mountain fronts to deposit sediments on the flat desert floor. These are called alluvial fans (Figure 2.10). They are common in many deserts. Bajadas are quite similar to alluvial fans except that they are broad and are formed by coalescing and overlapping alluvial fans. Bajadas as well as large alluvial fans are sources of groundwater in desert areas.
Water Resources of the United States
Published in Louis Theodore, R. Ryan Dupont, Water Resource Management Issues, 2019
Louis Theodore, R. Ryan Dupont
Throughout arid regions, the presence of dissolved minerals most widely limits the use of surface water and groundwater. Water is an effective natural solvent that dissolves minerals as it interacts with geologic materials on the land surface and within an aquifer system. Deep aquifers represent significant untapped water resources. The geochemical processes that occur under extreme temperatures and pressures over centuries, however, have increased the levels of salinity in most of these deep aquifers to that of seawater. Interactions between surface water and groundwater also control natural levels of salinity in streams and reservoirs. In many parts of the arid west, saline aquifers and thermal springs are major sources of base flow. The region’s characteristically high evaporation rates also increase surface and groundwater salinity. These natural processes are best illustrated by Utah’s Great Salt Lake, the largest surface-water body in the west, where salinity ranges from 5% to 25% by weight or 50,000 to 250,000 mg/L. For comparison, the salinity of the oceans is about 3.5% or 35,000 mg/L of total dissolved solids. Saline lakes, such as the Salton Sea and Mono Lake in California, are found in several closed basins in the west. Many more closed basins contain dry lake beds or playas such as Death Valley, California; Willcox Basin, Arizona; and the Bonneville Salt Flats in Utah. Trace elements also can occur naturally in water as part of the weathering process at levels that limit water use unless expensive treatment technology is applied (Anderson and Woosley 2005).
Machine learning-based prediction of sand and dust storm sources in arid Central Asia
Published in International Journal of Digital Earth, 2023
Wei Wang, Alim Samat, Jilili Abuduwaili, Philippe De Maeyer, Tim Van de Voorde
Although we evaluated the predictive performance of four ML methods based on multiple evaluation metrics in this study, the true distribution of SDS sources is crucial for model validation. More information on the spatial distribution of source areas based on SDS events should be used in prediction validation. In the model training process, a large number of non-SDS source points were randomly generated outside a 100-km buffer around SDS source points. With ground and aircraft observations, SDS source points can be associated with individual fields of farmland areas or dry lake beds where the eroding surface area is on the order of 1–100 km2 (Walker et al. 2009). Thus, 100 km is the maximum influence range of a given SDS source point, which is defined based on the potential dust source region. However, this can lead to SDS source points being mislabeled as non-SDS source points, which can result in biased predictions. Additionally, while the GEE platform allows users to rapidly analyze large spatial datasets, the higher-resolution data (90 m-Landsat) obtained thus far are difficult to apply to SDS source prediction across ACA. This also restricts the user’s ability to quickly display analysis results in the interactive map interface of GEE. Therefore, we used lower-resolution RS products and reanalysis data in this study. Additionally, upcoming studies should focus on the role of wind speed and vegetation in the control of SDS source areas (Al-Dousari et al. 2020). Relevant thresholds of these variables should also be considered to accurately predict SDS source areas.
Zebra rock and other Ediacaran paleosols from Western Australia
Published in Australian Journal of Earth Sciences, 2021
Laminated and varved shales of the Johnny Cake Member represent a different sedimentary facies (RG) of varved and laminated, red and green, shales, with thin sandstones and weathered tuffs of a lacustrine basin that was intermittently exposed like modern playas and salt lakes (Benison et al., 2007; Benison & Bowen, 2015). Thamberalg profiles with gypsum sand crystals are similar to dry lake Gypsids or Solonchak soils (McKenzie et al., 2004). Zebra rock (Wajing) profiles were rhyolitic feldspar and biotite tuffs with poorly drained lower horizons within the lake basins, and show acid sulfate weathering (Loughnan & Roberts, 1990). Red sandstone Danggang profiles were on local sandy soils, perhaps eolian lunettes which commonly flank playa lakes (Bowler, 1973; Fitzsimmons et al., 2014). Zebra rock’s intimate admixture of oxidised and gleyed areas with open system enrichment and depletion of iron over small distances, but with red at the top and grey at the bottom, is similar to soils within the zone of seasonal rise and fall of water-table (Vepraskas & Sprecher, 1997).
Simulating the meteorology and PM10 concentrations in Arizona dust storms using the Weather Research and Forecasting model with Chemistry (Wrf-Chem)
Published in Journal of the Air & Waste Management Association, 2018
Peter Hyde, Alex Mahalov, Jialun Li
Ideally, additional regulatory oversight could be brought to bear on these highly erodible land surfaces. Such oversight is hampered, however, by a different regulatory mechanism: the doubtful characterization of these dust storms as “natural, exceptional events” (Arizona Department of Environmental Quality [ADEQ] 2016). Ordinarily and traditionally, such natural events have been limited to forest fires and in 1980 the eruption of Mount St. Helens. Regions downwind of volcanic eruptions and forest fires cannot legitimately be held to achieve either air quality standards or visibility goals in their immediate aftermath, and, through the mechanism of natural/exceptional events, they are not. In most cases in Arizona, applying this legal mechanism to dust storms is problematic if not disingenuous. For those cases where truly natural landscapes such as dune fields and dry lake beds (playas) produce windblown dust, this policy makes sense and has been invoked. Contrariwise, when the trajectory of a dust storm, either dry cold front or monsoon, moves the storm cells over active or abandoned farm lands, it is present or former human activity that allows the gusty winds to erode the topsoils and produce the massive dust clouds. Invoking the “natural events” policy for these cases could be considered a regulatory ploy, one designed to keep such regions as Maricopa County in compliance with the federal air quality standards for PM10 and PM2.5. This regulatory end run may satisfy some of the regulators (and frustrate the public health community), but, more importantly, it poses a substantial roadblock for imposing emission reduction regulations on abandoned farm lands.