In arid and semi-arid regions it is quite often to encounter granular soils of high hydraulic conductivity. Loss of irrigation water occurs due to seepage as well as evaporation. Excess water resulting from irrigation of green yards in Eastern province of Saudi Arabia was found to seep down into ground or flow towards uncontrolled directions. Sand clay liners reinforced with geotextile materials can be designed to act as a smart barrier and used to harvest excess irrigation water. Engineering properties and hydraulic conductivity of the sand clay liners were investigated. The conditions for yielding optimum output were introduced based on the outcome of laboratory test results carried out for mixtures of Al Qatif clay material and fine dune sand. The study presents a framework for landscape designers to benefit from the idea and select the appropriate proportions that suit the intended liners. The collected water can be examined and used again in irrigation.

Three soil profiles were characterized from a sandy area situated in a transitional zone in the Tablas de Daimiel UNESCO wetland biosphere reserve (TDNP) in the Mancha Plain (Central Spain). The original thickness of the soil layer in this area was as much as 100 cm, but the combined effect of unbalanced cultivation (including irrigation) and an increasingly dry climate has partially eroded their natural properties, almost leading to a desertification process. The main properties of these soils, classified as Xeropsamments (Soil Survey Staff 2006) or Arenosols (IUSS Working Group WRB 2006), are the dominance of sand in the soil matrix, its basic character, and low soil organic matter and carbonate contents. Scanning electron microscopy of the quartz grain surfaces indicated that the superficial textures were commonly well preserved and characteristic of specific conditions of aeolian formation. Exoscopy revealed a mixture of sub-angular and rounded quartz morphotypes with well-preserved mechanical impacts on the grain surfaces. These percussion effects are characteristic of aeolian processes and confirmed that mechanical actions were more significant than chemical processes in their pedogenesis. This micromorphological study of the textural sands in the transitional zone of the TDNP revealed that the (red) sands were transported to this area by wind, probably from material of degraded red soils, and deposited on soil horizons previously developed over marls and limestones. The relict character of these materials and specially their susceptibility to degradation should be considered as a priority argument to preserve this area and introduce management measurements to avoid soil erosion.

Aeolian sand covers extensive areas of the Navajo Nation in the southwestern United States. Much of this sand is currently stabilized by vegetation, although many drier parts of these Native lands also have active and partly active dunes. Current prolonged drought conditions that started in the mid-1990s are producing significant changes in dune mobility. Reactivation of regional aeolian deposits due to drought or increasing aridity from rising temperatures resulting from climate change could have serious consequences for human and animal populations, agriculture, grazing, and infrastructure. To understand and document the current and future potential for mobility, seasonally repeated surveys were used to track the location of multiple active barchan dunes. By utilizing Real-Time Kinematic GPS field surveys and simultaneously collecting in-situ meteorological data, it is possible to examine climatic parameters and seasonal variations that affect dune mobility and their relative influences. Through analysis of the recorded data, we examined the fit of various climate parameters, and demonstrate that under the current prolonged drought, wind power is the dominant factor controlling dune mobility. Published by Elsevier B.V.

The formation and evolution of parabolic aeolian dunes depend on vegetation, and as such are particularly sensitive to changes in environmental controls (e.g., temperature, precipitation, and wind regime) as well as to human disturbances (e.g., grazing, agriculture, and recreation). Parabolic dunes can develop from the stabilisation of highly mobile barchan dunes and transverse dunes as well as from blowouts, as a consequence of colonisation and establishment of vegetation when aeolian sand transport is reduced and/or when water stress is relieved (by increasing precipitation, for instance). Conversely, existing parabolic dunes can be activated and may be transformed into barchan dunes and/or transverse dunes when vegetation suffers environmental or anthropogenic stresses. Predicted increases in temperature and drought severity in various regions raise concerns that dune activation and transformations may intensify, and this intensification would have far-reaching implications for environmental, social, and economic sustainability. To date, a broad examination of the development of parabolic dunes and their related transformations across a variety of climate gradients has been absent. This paper reviews existing literature, compares data on the morphology and development of parabolic dunes in a comprehensive global inventory, and scrutinises the mechanisms of different dune transformations and the eco-geomorphic interactions involved. This knowledge is then integrated into a conceptual framework to facilitate understanding and prediction of potential aeolian dune transformations induced by changes in environmental controls and human activities. This conceptual framework can aid judicious land management policies for better adaptations to climatic changes. (C) 2014 Elsevier B.V. All rights reserved.

An accumulated sand-belt formed along the upwind fringe of the desert oasis in Hexi corridor of Gansu province during the period of desert control for more than half a century. It is due to desertification combating through afforestation and setting up sand barriers. What ecological functions and ecological significance does it have? To find the answers, we conducted a comprehensive study of the sand-belt along the oasis fringe and analyzed the data of the 21 sample accumulated sand-belts. The results showed: 1) The accumulated sand-belt, as a result of desertification combating, has functions of windproof and sand-blocking. It is conducive to desertification combating along the oasis fringe. 2) Height is an important factor indicating the windproof function of the sand-belt. The taller the accumulated sand-belt, the greater the scope of desertification combating. 3) Currently, the accumulated sand-belt in Hexi oasis is still at the developmental stage. As long as it is well protected, sand invasion into farmland can be effectively controlled. In the future, the accumulated sand-belt will be a key point in desertification combating along the oasis fringe, especially on its sand ridge line. In the desert-oasis transitional area, fencing other than additional investment is needed. So less man-power measures will be taken if the sand-belt is taken into full use, which can reduce the fund investment and improve the effect of desertification combating.

In arid zones, many active aeolian dunes terminate at ephemeral and perennial desert rivers. The desert rivers show very high rates of sediment transport that cause deleterious downstream effects on the river system and ecology. High sediment loading has been attributed to severe water erosion of sparsely covered watersheds during infrequent but heavy rainfall. Although aeolian erosion is known to lead to high rates of wind-blown sand transport, direct confirmation of whether the aeolian processes accelerate or inhibit fluvial sediment loss is lacking. Here, we show that an aeolian-fluvial cycling process is responsible for the high rate of suspended sediment transport in a Sudalaer ephemeral desert channel in the Ordos Plateau of China. Frequent aeolian processes, but low frequency (once every 3years on average) flooding, occur in this region. Wind-blown saltating grains appeared to be unable to cross the desert channel because of interruption of channel-induced recirculating air flow, and therefore tended to settle in the channel during the windy seasons, leading to channel narrowing. During flooding, this narrowed channel was found to yield a threefold increase in suspended sediment loading and a 3.4-fold increase in the weight percentage of the 0.08-0.2mm sediment fraction on 18 July 2012. Loss of stored aeolian sand due to channel erosion accounted for about half of the total sediment yield in this watershed. These findings show that aeolian processes play an essential role in accelerating the sediment yield from a watershed characterized by aeolian-fluvial interplay and also suggest that the drier the region and the greater the aeolian process, the more the aeolian process contributes to fluvial sediment yield. Copyright (c) 2013 John Wiley & Sons, Ltd.

Large quantities of sand dunes occur along the NW and SE coastal belts which belong to very low rainfall Dry Zone coasts of Sri Lanka. The orientation depends on monsoonal wind directions, sand supply and wind strength. A scientific study on the dune sand deposits of the NW coastal belt in Sri Lanka was carried out to find out the suitability of the materials to be used for the construction industry in the Island. The distribution, thickness, type of materials and their physical properties were investigated in the field and some other tests were carried out in the laboratory. The laboratory analysis indicates that 95 % of the materials are quartz grains and the balance 5 % consists of a mixture of some heavy minerals, dust, clay, and fine sea shell fragments. Sand of fine to medium size with silt grains are sub-rounded to angular and tabular in shape. The degree of sorting and particle size of dune sands meets the soil properties required in the construction industry. The result indicates that dune sand could be effectively used in construction work without sieving and it is ideal for wall plastering due to its' uniformity. It could also be effectively used in concrete and in mortars mixing with coarse river sand and crushed rock sand.

This work focuses on the study of the effect of barley straws addition on the thermophysical properties of sand concrete intended for the construction of an external wall in arid regions. The work has been basically devoted to the study of the thermal properties of two river-dune sand concretes: one without barley straws (SC-W-BS) and another with barley straws (SC-BS). The effect of barley straws addition, wall thickness, air-gap within the wall, wall orientation as well as the wall surface coating on the time-lag (Phi) and decrement factor (f) of the materials have been discussed. The obtained results show that the addition of barley straws considerably improves the thermophysical properties of sand concrete (thermal conductivity, specific heat and density). In addition, the results obtained by the use of the EnergyPlus software and its application for an external wall made of these materials show that, in the case of SC-BS, the thermal insulation is markedly improved compared to the case of SC-W-BS. This thermal insulation is also improved when the thickness of the wall is higher and even a further improvement is possible if both faces of the wall are coated. Moreover, the addition of an air-gap within the wall, further improves its thermophysical behavior and the study of the wall orientation effect confirms the results of literature i.e. the south and east direction. Besides all that, the macro-structure of the studied composite appears relatively homogeneous with good adhesion 'straw-matrix'. (C) 2014 Elsevier B.V. All rights reserved.

The variability of climate in the South-West of Romania, in particular the lack of rainfall and low fertility of sandy soils, conduct to register in large surface important decreases of yields to the main crops. In this context, to promote sustainable agriculture in drought conditions, we have to found and recommend those species of plants that are more adaptable in existing thermo-hydric stress conditions and ensure good stability of yields obtained. The deepening drought in the south led to a chronic problem in southern Oltenia Plain, especially in area of sandy soils. Excessive droughts in 1992, 2000, 2002, 2007, manifested particularly severe in the South-West of Romania, was a typical example of a natural disaster. Harvests obtained in drought years were drastically affected and varied between 1-3 t/ha (maize), 1 t/ha (wheat), 500 kg/ha (soybean) and 500 kg/ha (sunflower) - [1]. Cowpea (Vigna unguiculata L. Walp) is one of the plants which recover with good results the biological potential of the mentioned area due to its resistance to drought and low claims against the natural fertility of the soil. Due to the high content of protein, both plant and grain, cowpea is considered the queen of areas with sandy soils, with multiple uses: human nutrition as pods or grains; improving soil fertility; inserting cowpea crop in rotation; using as green manure by cultivating the plant and in the stage of flowering and incorporating in the soil; through its participation in animal nutrition with sorghum or rye to obtaining of dried fodder and silage [2]. Because of biological and morphological particularities as: very strong root system with high power absorption, waxy coating on the leaves which would give a greater resistance to thermo-hydric stress conditions and the possibility of biological fixation of nitrogen thru symbiotic bacteria of Rhizobium genus, cowpea is successfully grown in different crop rotation on sandy soils area of Nigeria [3], [4]. Our research focused on increased resistance to drought, reduced requirements to soil fertility and high content of protein shows that cowpea can be a viable alternative for bean crop for human food and soybean crop used for animal feed, plants which are very sensitive to stress factors in areas with excessive drought.

This paper focuses on using geology theory analysis the factors of formation of the desertification in eastern Inner Mongolia area and puts forward prevention measures accordingly, emphasis on regional desertification prevention and control work should start from the objective reality. Desertification control work should pay attention to Geology theory.