Search

Conventional tillage coupled with monocropping and limited recycling of crop residues along with increased pressure from human and livestock population has led to the degradation of the soil, water resources, and the environment in the Middle East and North Africa (MENA). Conservation Agriculture (CA) considered as "climate-smart" agriculture, strives to achieve acceptable profits along with high and sustained production levels while concurrently conserving and regenerating soils and protecting the environment. The objectives of this paper are to review and synthesize available findings on CA, its past trends, current opportunities and challenges, evidence on potential benefits from its adaptation, to discuss its future outlook, and to make relevant recommendations for interventions and novel research needs for its wider diffusion in the region. In MENA, major research on CA has been mainly conducted in Morocco, Tunisia, Iran, and Syria, while Jordan, Lebanon, Iraq, Egypt embarked CA research fairly recently. About 25-40% out of the 53 million hectares total arable land is estimated to be suitable for CA in the region. In recent years a growing number of studies carried under a range of climatic, soil, management and cropping conditions in many countries of MENA reported several benefits including higher and more stable yields and profits, reduced risks of crop loss, labor requirements, soil erosion, and improved soil moisture and quality under CA system. Despite its benefits, adoption of CA in MENA is still very low for various reasons including: lack of affordable and well-adapted seeders, the complexity of the CA system which posed a major challenge for mostly uneducated farmers to comprehend, ill-conceived policies that promote cereal intensification hence inadvertently promote monocropping, tradeoffs between residue retention and livestock feed, lack of adequate policy and institutional framework and incentives to enhance farmers' adoption, and the private sector's active involvement in the dissemination of CA. The wider acceptance of CA requires the development of affordable and versatile no-till seeder alongside the implementation of integrated crop management practices. CA-based bundled agronomic management practices must be tailored to the biophysical and socio-economic environment. Finally, effective strategies for upscaling CA in MENA has to be developed by taking into consideration the unique features of the region. Despite the daunting past adoption trends and current challenges, we predict a bright future for CA in the region due to several factors including: rising energy prices and wage rates, the emergence of younger and more educated farmers, the advent of climate change, the increasing awareness on the degradation of land and water resources among farmers and policy makers, changes in dietary preferences subsequently increasing trends in demand and prices of legumes are expected to increase the desirability of CA and enhance its wider diffusion in MENA. [ABSTRACT FROM AUTHOR]

Abstract Archaeological studies typically describe arid areas as extremely unpleasant areas for human occupation and use. Without suggesting that arid areas are pleasant places, however, this paper provides a reassessment of the meaning of aridity for an area showing a vast amount of evidence of (past) human activities. Several climatic proxy data suggest that at the transition between the late Bronze Age and the Early Iron Age (around c. 1300-1100 BC) the southern Levant witnessed more arid conditions, while after 1100 BC relatively moist conditions would have prevailed. In drylands, small changes in temperature and water availability can have large effects on subsistence options. Building on cooperation between an archaeologist and a water scholar, this paper offers an approach to study how people in the past were able to craft a livelihood in the arid environments in the southern Levant and elsewhere. Focusing on the Zerqa area, the paper explores the potential of this cooperation by studying effects of climatic changes at the transition from the Late Bronze Age to the Iron Age through a modelling approach. Changes in temperature and moisture availability were simulated, showing that increased aridity could have been met by either naturally available water (especially groundwater) or artificially added water (although the timing appears to be crucial). While the model approach under discussion offers an approximation of the past, it shows the potential impact of climatic changes on the subsistence of past communities. It shows that details can mean the difference between survival or collapse. Highlights • Modelling provides boundaries for thinking about ancient resilience. • Rainfed crop yields could be sustained with irrigation, even in the frequent dry years. • Increasing aridity might have been a trigger for expanding the irrigation system. • The Zerqa Triangle was affected by the LBA crisis, yet continuity is visible as well. • Aridity did not necessarily bring crisis, even in arid areas like the Zerqa Triangle. [ABSTRACT FROM AUTHOR]

The effects of global climate change and human activities are anticipated to significantly impact ecosystem services (ESs), particularly in urban agglomerations of arid regions. This paper proposes a framework integrating the dynamic Bayesian network (DBN), system dynamics (SD) model, patch generation land use simulation (PLUS) model, and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model for predicting land use change and optimizing ESs spatial patterns that is built upon the SSP-RCP scenarios from CMIP6. This framework is applied to the oasis urban agglomeration on the northern slope of the Tianshan Mountains in Xinjiang (UANSTM), China. The findings indicate that both the SD model and PLUS model can accurately forecast the distribution of future land use. The SD model shows a relative error of less than 2.32%, while the PLUS model demonstrates a Kappa coefficient of 0.89. The land use pattern displays obvious spatial heterogeneity under different climate scenarios. The expansion of cultivated land and construction land is the main form of land use change in UANSTM in the future. The DBN model proficiently simulates the interactive relationships between ESs and diverse factors. The classification error rates for net primary productivity (NPP), habitat quality (HQ), water yield (WY), and soil retention (SR) are 20.04%, 3.47%, 4.45%, and 13.42%, respectively. The prediction and diagnosis of DBN determine the optimal ESs development scenario and the optimal ESs region in the study area. It is found that the majority of ESs in UANSTM are predominantly influenced by natural factors with the exception of HQ. The socio-economic development plays a minor role in such urban agglomerations. This study offers significant insights that can contribute to the fields of ecological protection and land use planning in arid urban agglomerations worldwide. • An integrated framework combining DBN, SD, PLUS and InVEST models was proposed. • Impact of natural and socioeconomic factors on ESs was determined under climate scenarios. • The spatial pattern of ESs was optimized and partitioned using DBNs. • ESs in arid oasis urban agglomerations are mainly affected by natural factors. [ABSTRACT FROM AUTHOR]

The agricultural and environmental functionality of irrigation districts is sometimes controversial, with salinity as a frequent argument in the arid countries. In the 20th century, the Spanish Ministry of Agriculture studied the degree and extent of salinity and other facets of irrigated districts in Spain by conducting soil surveys and land evaluations from the 1940s to the early 1980s. This article presents a--probably partial--list and the available details of these studies for the Ebro Basin. We had access to some of these studies, although for most of them we only have indirect information; we also indicate the existence of these kinds of studies for other regions of mainland Spain. However, updated systematic estimations of the extent and degree of soil salinity are unavailable for most of the irrigated lands in Spain and for many other dry countries. A feasible task, as shown further in the article, is screening the value of the still readable studies and selecting the irrigation districts whose past documentation and present status allow for a new evaluation of soils, or at least measuring their actual salinity for comparison with the previous data. The results will help irrigators, government agencies, and other stakeholders in the appraisal of the effects of agricultural practices--chiefly the application of water--and to re-design them if needed. We advocate for the collection and critical review of the surviving soil studies, and for their rescue through scanning and digitalization. This task is compelling due to the decay of the existing paper documents. [ABSTRACT FROM AUTHOR]

The southern rivers of Peru originate in the Andes Mountains and flow in a southwestern direction to the Pacific Ocean through one of the most hyper-arid regions of the world. During each sub-equatorial summer from December to February, rains and snow melt in the Andes increase the streamflow in these rivers, even as they pass through the 100 km arid zone to the ocean. This study quantified seasonal dynamics of 34 trace metal elements (TM) and other constituent concentrations in four southern river basins of Peru (Chili-Quilca, Tambo, Camana-Majes-Colca, and Ocoña) during 2019–2020. Consistent with previous studies, we observed that: (1) the river water in the southern basins had relatively high concentrations of B, As, Fe, Al, Mn, P, Pb and Ni, with As the most ubiquitous toxic TM in all the basins, often detected at concentrations surpassing Peruvian and USEPA regulated concentrations; and (2) basins with the most to least toxic TM contamination were the Tambo > Chili-Quilca > Camana-Majes-Colca > Ocoña. Seasonal streamflow strongly influenced the concentrations of twenty TM, with 15 TM (Al, Au, Ba, Cd, Co, Cu, Fe, Gd, Mn, Ni, P, Pb, Ti, Yb and Zr) consistently higher in the wet season, and with As, B, Ge, Li, and Pd higher in the dry season. Our results improve the understanding of seasonal variability and vulnerability in western Andes superficial water sources, which are highly influenced by both local geogenic and anthropogenic conditions. A Spanish translation of this paper is available in the online Supplementary Material. [Display omitted] • Arsenic is the most ubiquitous contaminant in surface waters of Southern Peru. • Al, Fe, As, B, Mn, P, Pb, and Ni exceeded the Peruvian water quality regulation. • Out of 34 metals studied, 14 showed a strong seasonal behavior (e.g., As, Pb and B). • Total recoverable metals trended better rather than dissolved metal with season. [ABSTRACT FROM AUTHOR]

The human history of southern Africa’s drylands is a history of discontinuities. This paper identifies several instances where different kinds of discontinuity seem apparent and different kinds of approaches have been, or could be, taken to address them over the past 25,000 years (the approximate time-frame of the Later Stone Age). Fundamental to all the cases examined is a basic feature of southern Africa’s geography, the distinction between summer-, winter-, and year-round-rainfall regimes that cuts across the sub-continent’s arid and semi-arid zones. Drawing where possible on emerging genetic and linguistic, as well as archaeological, data the paper then discusses a series of spatial and/or temporal hiatuses in the region’s cultural history from the Last Glacial Maximum to the introduction of domestic livestock. It concludes by considering two further discontinuities that underlie almost all studies of Later Stone Age hunter-gatherers and herders in southern Africa, regardless of environmental location: the relatively limited degree to which an archaeological record exists for the groups whose ethnographies are most heavily consulted, and the even more troubling disconnect arising from the extension across the whole of southern Africa of ethnographic analogies drawn from a very few populations living in its dryland biomes. [ABSTRACT FROM AUTHOR]

Abstract Over the last 30 years, geoarchaeological surveys undertaken in the Near East have offered a powerful way of studying, inter alia, water supply systems at a microregional to regional scale. However, efforts to synthesize the results of surveys at a sub-continental scale in order to understand local differences and similarities, and compare local strategies through time, require specific tools. In this paper, we develop a methodology designed to characterize and facilitate comparison of strategies employed across the arid areas of Western Syria. This requires microregional field studies undertaken at the level of specific landscapes to be integrated within a wider GIS framework, based upon thematic layers (soils, rainfalls, hydrology) at a uniform spatial scale of assessment (in this case the pixel of a Landsat image), and a common description of the agronomic potential in those areas in which specific hydraulic installations were employed. In contrast to the usual practice of modelling, which depends upon the downscaling of environmental data (land cover, rainfall maps) generated at a continental scale, we stress here the need to generalize upwards, from observations made at the microregional level, by using common descriptors and qualitative indicators. The GIS analysis of these data provides a weighted average model derived from field evidence for the different technical choices made (i.e. the decision to utilize specific water management devices) in relation to the various agronomic landscapes. Highlights • Long term history of Syrian arid steppic landscapes enlighted by water mastering techniques • Modelling spatial location of past water management devices in arid areas • Modelling the regional agronomic potential in Near East arid areas [ABSTRACT FROM AUTHOR]

Abstract MARAS (Monitoring of Arid and Semiarid Regions) consists of 379 ground monitors in Patagonia, a 624.500 km2 semiarid area of southern Argentina and Chile. The objective of this paper was to describe the system and analyze four variables of the initial data base. Floristic composition, diversity and cover were analyzed with intercept lines (500 points). Patches (resource-sinks areas) and Interpatches (areas that loose resources) were described using Gap intercept lines (50 m). Eleven Landscape Functional Analysis indicators were recorded in 10 interpatches: Soil stability, Infiltration and Nutrient cycling. Vegetation Cover was 43 ± 2%, Richness 15 ± 7 species/monitor, Interpatch Size 154 ± 134 cm and LFA Stability Index 46 ± 1%. Cover, Richness and Stability maps had bimodal distribution and maximum in S and NE areas, following rainfall gradients. Variability analysis shows that cover estimations are within 5% error at site and regional scales. Graphical analysis of single monitors shows observational biases in interpatch size and LFA Stability index. Richness estimations correlate significantly with α diversity (R2 = 0.80). Analysis of 5-year change in 115 monitors shows significant reductions in cover and interpatch length, especially N of the region. These base line evaluations enable analysis of future changes that were not possible with multiple techniques and isolated data bases. Highlights • 379 ground monitors of vegetation and soil were installed in Patagonia. • Six teams in two countries shared a single protocol and data base. • Errors of estimations at site and regional scales are acceptable. • Contour maps of main variables show gradients associated to aridity. • This baseline enables future change evaluation. [ABSTRACT FROM AUTHOR]

Highlights • A new formation mechanism of banded vegetation on hillsides of semiarid area is proposed. • The stronger internal competition reaction between plants leads to increase of wavelength of the vegetation stripes. • The migration speed of the vegetation stripes decreases with the increase of the internal competition intensity. Abstract Self-organised patterns of vegetation are a characteristic feature of semi-deserts. In this paper, we find the internal competition reaction between plants can lead to the formation of spatial vegetation patterns, which is different from the normal formation mechanism of long-range competition and short-range facilitation. It is also found that the internal competition between biomass has an effect on the characters of banded vegetation. In particular, it is shown that the internal competition reaction leads to the decrease of the migration speed and the increase of the wavelength of the stripe patterns. [ABSTRACT FROM AUTHOR]

Abstract Past water resource developments in dryland regions rarely estimated the full suite of environmental and social impacts arising from damming and diverting water for food production. Nowadays there is a greater focus on sustainable resource development which considers the economic, social and environmental costs and benefits. A challenge is to apply tools and methods which can capture the often disparate knowledge and data describing many costs and benefits. This paper describes a proof of concept application of a large Bayesian Decision Net to estimate the total utility of water resource development according to criteria of social, economic and environmental sustainability. We focus on two water-scarce catchments in remote northern Australia which are under investigation for development. The study catchments contain a diverse set of ecosystem services and socio-cultural values, including important Indigenous values and high value freshwater ecosystems. The Bayesian Decision Net was shown to have many properties that made it useful for performing a social, economic and environmental sustainability assessment, in particular its ease of construction; its ability to handle quantitative and qualitative data types; its preservation of system knowledge and; its ease of use in aiding decision making. From the perspective of the sustainability assessment in our case study, the total utility of water resource development for new irrigation is negative in both the studied catchments. The overall utility of water resource development could be positive if irrigation development is highly sensitive to the environment and there are very low environmental impacts, and much higher net economic returns to irrigators eventuate, possibly through higher commodity prices, lower capital costs of irrigation development or some combination of both. Highlights • Development of water resources involves trade-offs between economy and environment. • Integrated social-environment-economy sustainability (SEES) assessments support trade-offs analyses. • Bayesian Decision Networks (BDNs) support SEES assessments with diverse data types. • BDN applied to irrigation development scenarios of two remote catchments in north Australia. • The economic and ecosystem service benefits of the case study irrigation developments are questionable. [ABSTRACT FROM AUTHOR]

Desert tourism has grown steadily in several regions of the world, due to a post-modern fascination with remoteness, barrenness, silence and solitude. This paper evaluates the trend towards tourism development in South Africa's arid Karoo region. It utilises several methodologies – analysis of discourse, demand and supply – to track the changing profile of tourism in the Great Karoo. The paper concludes that the reputation of the Karoo has shifted profoundly from being hostile, dangerous and boring to being attractive, enticing and spiritual. At the same time, tourists are increasingly expressing favourable opinions of the Karoo as a destination, while accommodation facilities are growing apace. The overview also finds that tourism services in some Karoo towns are developing at a much faster rate than others, so the tourism performance is uneven. A survey of tourists in the Karoo found that the arid environment and small-town ambience offer significant attractions, and Karoo guest houses have a positive outlook for the future. These findings suggest that the Great Karoo is indeed in the process of becoming a tourism destination. [ABSTRACT FROM AUTHOR]

The aspirational goal of a land degradation neutral world, to be realized by reducing the rate of land degradation and increasing the rate of restoration of degraded land, was agreed at the Rio+20 Conference in 2012. This paper evaluates the feasibility of introducing a Land Degradation Neutral (LDN) scheme as an activity of the United Nations Convention to Combat Desertification (UNCCD). It concludes that national and international implementation would involve political, organizational and technological challenges. Monitoring restoration of desertified land by revegetation would be feasible immediately, but monitoring cuts in national rates of desertification would not, because no baseline rates are currently available; national and international scientific capacities to measure desertification are limited; and further scientific knowledge is required to supplement existing knowledge of desertification processes and of land use and land cover change processes generally. This paper therefore suggests introducing an LDN scheme in phases. Phase 1 would focus on restoring degraded lands, improving national land use planning systems, and establishing international and national monitoring capacities. Phase 2 would reduce desertification rates with the help of fully integrated land use planning and monitoring systems. Phase 3 would set a target year for realizing an LDN goal, based on experiences in Phases 1 and 2. All three phases would be informed by accessing existing scientific knowledge, and gaining new knowledge by launching a scientific LDN process that can evolve in parallel with the political process. [ABSTRACT FROM AUTHOR]

Water is a scarce resource in arid regions, and hence water harvesting is critically important in these regions for which many different means are adopted including groundwater and rainwater harvesting. This paper examines the feasibility of rainwater harvesting from roof catchments in arid regions of Australia. For this, ten representative locations in the arid regions of Australia are selected. Also, ten different sizes of rainwater tanks ranging from 5 kL to 50 kL and three different combinations of water uses are considered. A model is developed to simulate the performance of a rainwater harvesting (RWH) system. It is found that the reliability of a RWH system is highly dependent on mean annual rainfall at the location of interest. It is found that a 20 kL tank can provide a reliability of 61%–97% for toilet and laundry use depending on the location within the Australian arid regions. At the current water price, RWH system is not financially viable in the Australian arid regions. The methodology adopted in this paper can be adapted to other similar arid regions of the world. [ABSTRACT FROM AUTHOR]

Groundwater markets improve the agricultural economy by transferring water entitlements from low-efficient users to high-efficient ones to maximize productivity. Aiming at developing an efficient groundwater market, the environmental effects of the market mechanism should be assessed, and a reliable method for monitoring water consumption needs to be employed. Toward this end, this paper proposes three annual smart groundwater market mechanisms to maximize water net benefits, minimize groundwater withdrawal, and precisely measure water consumption in agricultural fields. To guarantee the aquifer's safe yield in each mechanism, a groundwater simulation model (i.e., Groundwater Modeling System (GMS)) is used to control groundwater table drawdown at the end of the planning horizon. In addition, the fields' evapotranspiration (ET) is estimated using Surface Energy Balance Algorithm for Land (SEBAL) and Mapping Evapo Transpiration at high Resolution with Internalized Calibration (METRIC) algorithm to measure the net groundwater consumption during the market. In this regard, we evaluated the algorithms' performances using observed data from a local lysimeter. They are applied to the Nough plain in Iran to assess the effectiveness of the proposed market framework. The findings illustrate their efficiency in recovering approximately 80% (23.33 million cubic meters (MCM)) of groundwater loss due to overexploitation in the study area and increasing the users' annual benefits by 10.6% compared to the non-market condition. In addition, results imply that the METRIC model approximates daily crop ET with a higher accuracy level than the SEBAL model with RMSE, MAE, and Percentage Error of 0.37 mm/day, 0.32 mm/day, and 14.92%, respectively. This research revealed that the proposed market framework is a powerful tool for reallocating water entitlements and increasing water productivity in arid and semi-arid regions. • A groundwater market is proposed to promote economic and environmental situation. • The uncertainty of available water is incorporated in the proposed methodolgoy • Designed market mechanisms recover nearly 85% of groundwater loss in the study area. • The market framework raises the economic benefit by 128.7 billion rials annually. • METRIC algorithm approximates daily crop evapotranspiration with RMSE of 0.37 mm. [ABSTRACT FROM AUTHOR]

Abstract: Biofuels are considered as a climate-friendly energy alternative. However, their environmental sustainability is increasingly debated because of land competition with food production, negative carbon balances and impacts on biodiversity. Arid and semi-arid lands have been proposed as a more sustainable alternative without such impacts. In that context this paper evaluates the carbon balance of potential land conversion to Jatropha cultivation, biofuel production and use in arid and semi-arid areas. This evaluation includes the calculation of carbon debt created by these land conversions and calculation of the minimum Jatropha yield necessary to repay the respective carbon debts within 15 or 30 years. The carbon debts caused by conversion of arid and semi-arid lands to Jatropha vary largely as a function of the biomass carbon stocks of the land use types in these regions. Based on global ecosystem carbon mapping, cultivated lands and marginal areas (sparse shrubs, herbaceous and bare areas) show to have similar biomass carbon stocks (on average 4–8 t C ha−1) and together cover a total of 1.79 billion ha. Conversion of these lands might not cause a carbon debt, but still might have a negative impact on other sustainability dimensions (e.g. biodiversity or socio-economics). Jatropha establishment in shrubland (0.75 billion ha) would cause a carbon debt of 24–28 t C ha−1 on average (repayable within 30 year with yield of 3.5–3.9 t seed ha−1 yr−1). Land use change in the 1.15 billion ha of forested area under arid and semi-arid climates could cause a carbon debt between 70 and 118 t C ha−1. This debt requires 8.6–13.9 t seed production ha−1 yr−1 for repayment within 30 years. If repayment is required within 15 years, the necessary minimum yields almost double. Considering that 5 t seed ha−1 yr−1 is the current maximum Jatropha yield, conversion of forests cannot be repaid within one human generation. Repayment of carbon debt from shrubland conversions in 30 years is challenging, but feasible. Repayment in 15 year is currently not attainable. Based on this analysis the paper discusses the carbon mitigation potential of biofuels in arid and semi-arid environments. [Copyright &y& Elsevier]

A practical approach for the assessment of surface water and groundwater resources in rain-fed mid-mountain domains of arid to semi-arid zones is much needed, especially in rural areas for which groundwater is the only reliable and permanent water supply source. This is the case in the Coquimbo region (29°15′- 32°10′ S latitude) of north-central Chile, where groundwater is needed for human consumption but also for agricultural and mining activities at a small to medium scale. This paper examines the usefulness of community knowledge, as encoded in the historical record, for identifying water resources. The existing record of wells and springs in the Coquimbo region is used as a guide to the identification and characterization of structural patterns that may influence the distribution of water resources. The proposed approach combines simple graphical, statistical and geostatistical methods to identify patterns, likely related to local and regional structural controls that influence the distribution of groundwater resources. In the Coquimbo area, these influences tend to align in NW and NE orientations that approximately coincide with regional geological trends. The methodology presented has the potential to form a first step in the search for additional water resources in the Coquimbo region, and may be useful for targeting detailed field studies on the basis of community and historical knowledge in many arid and semi-arid rural areas. [ABSTRACT FROM AUTHOR]

For several decades it been argued that episodic behavioral dynamism provides a better explanation for Australian arid zone social organization than earlier models founded on perceptions of long term, widespread cultural conservatism. This new understanding continues to develop with the consideration of rock art as a behavioral proxy. The development of a rock art style sequence in the Australian Western Desert has modelled for changing occupation indices and art production modes through time based on environmental changes and their likely effects on mobility patterns and territoriality (McDonald and Veth, 2013a). This model which sees rock art accompanying the first peopling of Australia’s deserts and stands in stark contrast to that of Smith (2013) which sees rock art as a mid-Holocene addition to the adaptive social repertoires of arid-zone peoples. We have argued that rock art provides evidence for an early mapping onto arid landscapes and that there is a long, albeit syncopated, arid zone style chronology. Early pigment rock art dates from Sulawesi (Aubert el al., 2014) support the view that symbolic behaviour was part of the social repertoire of human groups colonizing Australia and its interior. This paper tests the arid-zone style sequence by quantifying the synchronic and diachronic stylistic discontinuities observable at Kaalpi and Katjarra – two style provinces in the Australian Western Desert. While stylistic variability in the recent past demonstrates the nature of synchronic discontinuity in arid zone symbolic behaviour, punctuated changes in style graphics and changes in the way that this art has been placed through time demonstrate deep-time stylistic discontinuities, providing support for the phased art sequence and evidence for earlier configurations of arid-zone social networks. [ABSTRACT FROM AUTHOR]

Long-term impacts of drought, such as groundwater decline, can emerge during a persisting drought. Though not easily visible, they are severe and harder to cope with. Groundwater is considered a resilient source during drought in semi-arid areas. In this paper the response of a coastal aquifer to meteorological drought severity is investigated. The relation between drought severity and natural undisturbed coastal aquifer flow conditions is determined, based on the seawater intrusion extent, at a temporal scale. The Reconnaissance Drought Index (RDI) is used to assess the meteorological drought severity, since it incorporates precipitation and potential evapotranspiration, which both affect the recharge processes. Recharge volumes for different timeseries, estimated through a hydrological model, are used as input to a transient variable-density and salt transport numerical model. An indicator based on the freshwater volume and RDI index, are used to assess the aquifer response to drought. The multi-year drought effect is also investigated. The results show that the RDI index can be utilised successfully to associate the meteorological drought with aquifer flow conditions. Specifically, a reliable early prediction of the freshwater availability at the end of the hydrological year can be achieved by the RDI of the first semester. [ABSTRACT FROM AUTHOR]

Mammalian species inhabiting arid landscapes exhibit various levels of mobility in order to cope with unpredictable spatiotemporal dispersion of resources. However, the space use and ranging behavior of many species in drylands is poorly understood, especially for large carnivores in Asia. Accommodating the long-distance movements of mammalian carnivores is a major challenge in conservation, particularly for threatened and highly mobile species. The Asiatic cheetah Acinonyx jubatus venaticus , a critically endangered subspecies found only in arid areas of Iran, exhibits high levels of mobility. In the absence of satellite collars, this paper outlines ranging patterns of the majority of the Asiatic cheetah’s known population. A total of 17 independent cheetahs (11 males; 6 females) were detected with camera traps that were deployed on eight reserves between January 2011 and May 2016. The animals displayed extensive movements (up to 217 km between furthest known locations) and at least nine adult cheetahs were known to move between multiple reserves in central Iran. This mobility may follow a “nomadic” ranging pattern, a non-sedentary behavior with irregular timing and movement directions. The ranging behavior documented here must be considered when designing monitoring efforts to determine population and occupancy trends for this wide-ranging elusive carnivore. Although preliminary, our results show that improving protection beyond the current network of cheetah reserves, particularly along corridors, should be a top priority to safeguard the persistence of the Asiatic cheetah. [ABSTRACT FROM AUTHOR]

Abstract: Southern Spain’s semi-arid habitats are a Mediterranean ecosystem modelled mainly by historic factors which make them unique in comparison with North African deserts. Southern Spanish vertebrates have adapted to the recent emergence of semi-arid habitats in varying degrees of success. This paper reviews the current status of these terrestrial vertebrates (amphibians, reptiles, birds and mammals), their origins and their main features in relation to this biogeographic area. The vertebrate fauna of the semi-arid southeast of the Iberian peninsula differs widely from the one in the semi-arid Maghreb mainly because the former is composed by generalist vertebrates and much less so by species adapted to arid conditions. Moreover, a large fraction of the vertebrates in the semi-arid Iberia does not exploit the semi-arid areas but depends on riparian and human-managed habitats. The species diversity is rather low since only a small fraction of Palaearctic, European or Mediterranean species can adapt to the ecological limitations imposed by aridity and dwell in these semi-arid habitats. Such adaptations comprehend features like trophic plasticity, low morphological specialization, high dispersal ability, shortened life cycles and behavioural mechanisms to exploit the limited resources available. This paper identifies major conservation issues and proposes specific courses of action. [Copyright &y& Elsevier]

Abstract: This is the first of two papers that describe the surface hydrology of the Lake Eyre Basin (LEB) (1,140,000km2) in central Australia and compares some key characteristics with those observed from arid regions globally. This paper concentrates on annual rainfall, whereas the second paper is devoted to streamflow. The first part describes the LEB''s climate (arid to semi-arid), which is dominated by a subtropical high pressure ridge stretching latitudinally across central Australia. Then follow major analyses that include the characteristics of rainfall, wet and dry spell lengths and cumulative surpluses and deficiencies, rainfall trends and intra- and inter-decadal fluctuations, and the relationship between rainfall and El Niño-Southern Oscillation (ENSO). The paper concludes with six conclusions, the key ones being: the variability of the annual rainfall (based on the coefficient of variation) in the LEB is approximately 60% greater than that found for stations located in arid regions in the rest of the world; there is a bias towards longer lengths of dry years than observed in the rest of Australia; and, there is a significant lag correlation between rainfall and ENSO, particularly in the east and in the latter part of a year. [Copyright &y& Elsevier]

Abstract: This is the second of two papers examining the surface hydrology of the Lake Eyre Basin (LEB) (1,140,000km2) in Australia. The streams are unregulated and are characterised by extreme discharge variation. The analyses reported cover only surface hydrology and include comparisons with arid zone catchments globally. The paper discusses spatial runoff and annual streamflow characteristics, flow duration and baseflow index (BFI) analyses, annual flood frequency analysis and flood transmission losses, a water balance study, wet and dry run length analysis and, finally, yield from hypothetical reservoirs located across the LEB. There are 12 conclusions listed at the end of the paper. We identify two highlights as follows: [•] The coefficient of variation of annual flows, Cv, varies from 0.98 to 2.62. Compared with 45 arid zone rivers world-wide excluding Australian rivers, the annual Cv of the LEB streams are approximately double the average variability found world-wide. [•] Large transmission losses occur as flood flows move down the middle reaches of the major river systems. The transmission losses vary non-linearly with flood size as a result of differing transmission efficiencies between primary channels and the floodplain, and varying floodplain utilisation. [Copyright &y& Elsevier]

Abstract: This paper establishes an eight thousand year history of anthropogenic metal pollution at one of the oldest, most important and longest sustained sites of the extraction and smelting of copper ores in the Old World: the Faynan Orefield in Jordan, which is located between the hyper-arid southern desert and the front of the wetter Mountains of Edom. The modern land surface is shown, in significant part, to be a complex palimpsest of archaeological sites, metal pollution of various ages and ore processing deposits. Quantitative and qualitative observations of the storage and cycling of heavy metals through the local natural and domestic systems have produced a body of information on processes with which the past has been interpreted. Heavy metal concentrations in semi-continuous sedimentary bodies indicate that over the last 1500years, metals were removed by natural processes at a comparatively slow rate given the scale of the original anthropogenic metal burden: the proportions of lead with respect to copper have increased as the overall metal burden has been lowered. Distinctive anthropogenic metal-pollution signatures have been detected in ash- and charcoal-rich deposits that were discarded onto the banks of a perennial stream in the late Neolithic. At present, the nature of the human activities that might have produced these pollution signatures is unknown. Substantial metal pollution from industrial-scale smelting activity was present from the Early Bronze Age. The intensity of heavy metal pollution produced in Classical Times locally exceeded that recorded at major European copper smelting centres in the nineteenth century A.D. The pollution evidence indicates that intensive copper smelting at the immediate area took place until approximately the end of the Byzantine period; with the exception of one further minor episode of smelting radiocarbon dated to cal. BP 530–330. An observed partial, but perhaps significant, parallelism is also noted between this local record and the records of the metal burdens of the northern hemisphere determined at mire or ice-sheet sites at high-altitudes or high-latitudes. The paper discusses the extent to which this parallelism might be a geochemical indicator of the actual existence of “economic systems” of a geographical scope and scale to have both exercised substantial “pull” upon the resources of such isolated and difficult locations at the Wadi Faynan, and to have generated sufficient overall metal pollution to have materially altered the chemistry of the global atmosphere. The comparative absence of quantitative information upon the nature, spatial scale and impacts of human, industrial and natural processes affecting metal-pollution in other metal-rich arid lands provides a significant impediment to such approaches that seek to research “locally and think globally”. [Copyright &y& Elsevier]

Abstract: We discuss a new conceptual framework for arid and semi-arid systems that accounts for nonlinear dynamics and cross scale interactions in explaining landscape patterns and dynamics. Our framework includes a spatial and temporal hierarchy, and five key interacting components that connect scales of the hierarchy and generate threshold behaviors: (1) historical legacies that include climate, disturbance, and management regimes, (2) dynamic template of patterns in ecological variables and spatial context, (3) vertical and horizontal transport processes (fluvial, aeolian, animal), (4) rate, direction, and amount of resource redistribution between high and low resource areas, and (5) feedbacks among plants, animals, and soils. We illustrate how this framework can be used to understand, forecast, and manage ecological systems that exhibit nonlinear dynamics across a range of spatial and temporal scales. This paper provides the foundation for a series of papers from the Jornada Experimental Range ARS-LTER research site in southern New Mexico, USA that support this new conceptual framework. [Copyright &y& Elsevier]

With their modest rainfall, arid regions are characterized by relatively fewer species than the better-watered biomes. But this makes it all the more important that the biodiversity that is present in arid environments be given even higher priority; for each species lost from an arid region, the percentage of loss for the region''s biodiversity is much higher than in more species-rich regions. And some species, such as bees and ants, are particularly diverse in arid habitats. Realizing the importance of biodiversity in the arid regions where they live, local people have devised numerous ways of limiting their impact. Historically, such regions have been especially subject to changes in climate, which affect productivity; these changes have often been accompanied by conflicts. The paper will describe these from various parts of the arid world, as a basis for comparison. The paper will also examine economic issues relating to biodiversity in arid lands, focusing especially on the relationship between biodiversity and various kinds of development projects. The major challenges in implementing the Convention on Biological Diversity (CBD) in arid lands lie not so much in the biology of the species concerned, but rather in the social, economic, and political arenas within which people operate. We need to build a broader constituency for conserving biodiversity, extend the responsibility for conserving biodiversity far beyond government, bring local people into the conservation movement, ensure that sufficient information is available to those who need it, restore degraded ecosystems, and stimulate far greater public support for biodiversity. [Copyright &y& Elsevier]

With conservation of biological diversity depending as much on socioeconomic as on biological processes, this paper stresses the importance of clear policy objectives to guide strategies for preserving biological diversity. The first requirement is to define the essential elements and socioeconomic importance of biological diversity, so that these can be accommodated adequately in a national programme for sustainable rural development.Efficient application of this programme requires that its goals be clearly enunciated in national policy. There should also be maximum political support for its effective sociopolitically, economically and ecologically rationalised implementation by an accountable authority through a conducive institutional framework. Experience suggests that proprietorship and price are prime elements that need to be reconciled in such a framework of positive and negative incentives to individuals, to mitigate the opportunity costs and encourage the conservation of biodiversity. The present paper considers how these institutional requirements may be met, with particular reference to the special characteristics found in arid areas. [Copyright &y& Elsevier]

The present paper examines the influence of physical catchment properties on baseflow in semi-arid environments. It relates the dimensionless quantity, baseflow index (BFI) derived from data-based mechanistic modelling approach to dimensionless indices representing topographic, geologic and climatic properties. The relationship is derived using a progression of techniques, from inspection and correlation analysis, through stepwise regression and finishing with multiple regression. The BFI has a strong relationship with climate and geology. Catchments with high rainfall or low evapo-transpiration underlain with granites or basalt tend to give high baseflow. Within the topographical parameters tested, drainage density index has strong relationship with BFI. The approach used in this paper provides a viable alternative for baseflow estimation on ungauged semi-arid catchments using drainage density, geology and climate indices as key factors. [Copyright &y& Elsevier]

Urbanization has brought about dramatic changes in the urban environment in China and its associated human population and transportation systems in recent years. However, urbanization in the oases of arid regions of China has been little studied and remains poorly understood. This paper aims to analyze spatiotemporal changes in an urban landscape along major vehicular road transects and compare the relationship between urban growth and transportation in Jiuquan, an oasis city in an arid region of China. We integrated remote sensing images, landscape metrics, and urban-rural gradient analysis to address these questions. The results showed that major vehicular roads stimulated Jiuquan's urban expansion, especially with regard to built-up land containing urban green land areas. Oasis urbanization not only increased landscape fragmentation and structural complexity, but also followed a linear branching, leapfrogging growth pattern characterized by “axial clumps” extending from downtown into rural areas along the road network. The primary source of urban land was not agricultural land, but unused land. These results also indicated that the transect approach implemented along representative roads was effective for studying the urbanization of oasis cities. Such an approach could be applied to master planning in similar oasis cities throughout arid China. [ABSTRACT FROM AUTHOR]

This paper investigates how Borana pastoralists of southern Ethiopia have adapted resource use and livestock mobility practices amid multiple constraints including rising population, loss of rangeland to other pastoral communities and changing access rights, among others. This study uses an innovative multi-scalar methodology to understand how herders' grazing management decisions are made within a context of communal regulations governing access to resources. Grazing itinaries specifying the grazing units used during the past year were established for 91 cattle herds and daily mobility was recorded through 12 months of GPS data monitoring of three herds in three zones within the Borana rangelands. The results revealed communal reorganisation of the grazing areas into units with designated periods of access. Despite the reorganization, herd mobility is severely limited, but to different degrees. In the zones facing most constraints, herd mobility is restricted to the grazing areas within proximity of the respective herder's settlement. However in all the areas, movement outside the herd owners' zone of residence is only practiced as escape mobility, ‘ baqa’ (to flee); instead of the formerly common ‘ godanna’ (to move). These constraints impede fundamental herd mobility needed to meet livestock nutrient requirements, which then affects resilience of the pastoral system. [ABSTRACT FROM AUTHOR]

This paper develops and applies an integrated and participatory methodological framework to assess land degradation in pastoral systems through an ecosystem services (ES) lens in a semi-arid region of northern Nicaragua. We initially integrated local and scientific knowledge to assess ecological changes and understand the links with ecosystem services supplied by the local grazing system. Hence, we discuss land degradation features and test a state-and-transition ecological model, that is, we developed jointly with local farmers the hypotheses to understand transitions between ecological states and these hypotheses were then evaluated through an inventory of vegetation and an assessment of soil properties and seed bank composition. The assessment reveals that shifts in ecological state do not cause permanent soil properties changes, but that at a landscape scale they can limit production, affecting local livelihoods. The framework proposed provided local farmers with relevant information and facilitated communication with researchers, enabling them to use the co-constructed knowledge to implement adaptive management strategies to improve local productive systems. [ABSTRACT FROM AUTHOR]

Identifying, recording and monitoring land cover change on the Earth's surface is a complex procedure. Spatio-temporal modelling is an effective approach to simplifying and simulating the process. Existing spatio-temporal modelling methods are typically based on either, an overlay of multi-temporal land cover maps, or temporal trend analysis of spatial pattern indices. Consequently, an understanding of the spatial dynamics of any changes is either fragmental in the former case, or invisible in the latter case, due to the lack of adequate geographical location information. In the arid zone of western China, a widely accepted belief is that rapid farmland expansion and the subsequent abandonment of the farms, or their mis-management, would lead to soil salinisation and desertification. In order to better understand the spatio-temporal pattern of farmland change, this paper proposes an integrated approach that combines the two methods of pixel-based trajectory analysis and class-level spatial pattern metrics. Multi-temporal remote sensing images were collected beginning in 1994, a year that captured the initial effects of the period of rapid farmland expansion. Historical change trajectories were established for each pixel and categorized according to change types ( i.e . expanding or shrinking). The spatial dynamics of farmland change can then be illustrated by mapping the change trajectory classes. Spatial patterns of farmland change were quantified by employing distribution-related landscape metrics, such as indices of interspersion (IJI), connectivity (COHESION) and isolation (ENN), to analyse farmland development models of the two river basins in the study area. Shape indices, including overall shape (nLSI) and edge shape (FRAC), were applied to appraise the structural stability of the farmlands over time. Results indicate that, over the past two decades, the area subject to farmland expansion was significantly larger than that experiencing farmland abandonment. The relatively rapid expansion of farmland exhibited a concentrated pattern, and generally followed a layer-based development model. The study showed that the proposed research method effectively visualized and quantified the spatio-temporal dynamics of farmland change. [ABSTRACT FROM AUTHOR]

The paper analyzes local perceptions and practices related to the quality, extraction, and use of fuels firewood by the inhabitants of two protected areas. Our working model assumes the existence of patterns of preference, use and acquisition of firewood, depending on the social actors involved, and their perceptions. Our research developed through: the making of a reference collection and the applicationand of in-depth interviews and semi-structured surveys. We identified the most frequently used species and those with the greatest number of uses. The presence of patterns in the provisioning of energy source, and of firewood gathering and use, were identified in different actors. Through the application of a PCA analysis, and the study of native categories, patterning in the grouping of species was established, according to the local firewood classification. The latter relate to differences in the ease of ignition, in the durability and temperature of the flame and/or embers and the amount and type of smoke or ash produced. On the basis of ecological and perceptual information, a ranking of local priorities for the conservation of woody species is proposed. Finally, we discuss the relevance of sociocultural patterns of local perceptions of firewood use for conservation. [ABSTRACT FROM AUTHOR]

The paper focusses on the impact on dryland ecosystems of conflicting governance in the regulations of land use, water for irrigation and electric energy from photovoltaic installations (PV). The research uses the empirical results of a panel data model based on long time series that enable sensitivity of the main crops to energy cost and the viability of the solar panel system connected to the grid to be identified. We present evidence of the private and social benefits of investments in PV to improve the gross margin of farmers and decrease the carbon footprint of the irrigated areas. Relevant regional disparities in the sensitivity of the main crops explain the regional competition for low-cost water resources and the social conflicts associated with water governance. The Feed-In Tariff system for a PV system is evaluated as a tool to reach clean energy targets and preserve the populations working and living in irrigated drylands. An evaluation of the water desalination plants based on PV is analysed as an alternative to balance the hydric resources of intensive irrigated systems. The main conclusion is that coordinated regulation in energy and water policies may improve farmers' profitability and accelerate the speed in reaching environmental targets in drylands. • The paper assesses the economic viability of grid-connected photovoltaic installations of principal crops. • Since the liberalisation of the energy market, the electricity bill of irrigators become substantially higher. • Adaptation to climate change means to switch to PV irrigated systems to preserve gross land margins. • The contradictory and time unstable regulations send conflicting signals slowing the path to a clean irrigation system. • Our main conclusion is that the European Commission has a relevant task in coordinating water and energy regulations in arid lands. [ABSTRACT FROM AUTHOR]

The arid region of Northwest China, located in the central Asia, responds sensitively to global climate change. Based on the newest research results, this paper analyzes the impacts of climate change on hydrology and the water cycle in the arid region of Northwest China. The analysis results show that: (1) In the northwest arid region, temperature and precipitation experienced “sharply” increasing in the past 50 years. The precipitation trend changed in 1987, and since then has been in a state of high volatility, during the 21st century, the increasing rate of precipitation was diminished. Temperature experienced a “sharply” increase in 1997; however, this sharp increasing trend has turned to an apparent hiatus since the 21st century. The dramatic rise in winter temperatures in the northwest arid region is an important reason for the rise in the average annual temperature, and substantial increases in extreme winter minimum temperature play an important role in the rising average winter temperature; (2) There was a significant turning point in the change of pan evaporation in the northwest arid area in 1993, i.e., in which a significant decline reversed to a significant upward trend. In the 21st century, the negative effects of global warming and increasing levels of evaporation on the ecology of the northwest arid region have been highlighted; (3) Glacier change has a significant impact on hydrology in the northwest arid area, and glacier inflection points have appeared in some rivers. The melting water supply of the Tarim River Basin possesses a large portion of water supplies (about 50%). In the future, the amount of surface water will probably remain at a high state of fluctuation. [ABSTRACT FROM AUTHOR]

Native desert plants have structural adaptations that maximize photosynthesis rates and minimize water loss. They can be successfully utilized as soil cover crops in drip-irrigated vineyards where water availability is low. The objective of this paper is to study seed germination conditions and to recommend which best species is most apt as soil cover crop in drip-irrigated vineyards. Seed weight (the higher the seed weight, the greater the success of mechanical seeding) and germination tests (at 15, 20, 25, 30, and 35 °C in light and dark conditions) were carried out for six species native to Mendoza, Argentina. Germination percentage (GP) and mean time germination (MTG) were calculated. Digitaria californica (C 4 ) had the highest GP (97% in light condition), which is recommended as a cover crop because of its seed germination potential. Pappophorum phillippianum (C 4 ) had a 70% GP in light conditions (regardless of temperature) and a high seed weight. Leptochloa dubia (C 4 ) and Sporobolus cryptandrus (C 4 ) reached the highest GP at the highest temperature, although S. cryptandrus had the lowest seed weight. Nassella tenuis (C 3 ) averaged 54% GP at 25 °C in light conditions. The GP of Setaria leucopila (C 4 ) was not affected by temperature (26% in light, and 16% in darkness). Based on the GP results, S. leucopila was the worst choice of the six species. Hence, during seeding, soil temperature should be high (>20 °C) to ensure a rapid plant establishment of all species. [ABSTRACT FROM AUTHOR]

Water systems lie at the interface between nature and culture and in that perspective are a rich but under-explored research object. Their temporalities (construction, maintenance, abandonment) represent an image of a social, cultural, economic and political context as well as changing environmental conditions. This socio-environmental signature recorded in the spatial organization, sedimentary fill and profile of hydraulic structures can be reconstructed by means of a systemic cross-disciplinary approach (geoarchaeology, chronology and paleoenvironment). The principle and limits of the methods applied to this research object are presented and discussed in this paper. While they can be applied to different environmental contexts, they will be presented through the example of Hohokam irrigation systems in the semi-arid Phoenix basin, Arizona, where this approach has been applied as a whole. As water systems are structural elements of the spatial and socio-political organization of societies, this approach will provide elements to discuss the relative impact of human and/or environmental factors on landscape change and cultural shifts, and measure the long-term vulnerability and resilience of agricultural communities to regional environmental changes. [ABSTRACT FROM AUTHOR]

A significant part of the world's largest river basins are located in areas of arid and semi-arid climate, such as the Amu Darya, Jordan, Murray-Darling, Yellow River, and Aksu-Tarim river basin. These river basins are experiencing water scarcity resulting in conflicts between upstream and downstream, conflicts between water users, and degradation of the natural ecosystems. Therefore, in many river basins, including the Aksu-Tarim river basin, water quota systems have been established, in order to allocate water under scarcity. The Aksu-Tarim river basin (NW China) has developed into one of the most important cotton production areas worldwide. In this paper, we aim at assessing the water consumption through irrigated agriculture, mainly cotton, and natural vegetation in the Aksu-Tarim river basin against the background of this water quota system. Firstly, we map the evapotranspiration (ET a ) as water consumption of irrigated agriculture and natural vegetation in the Aksu-Tarim river basin. Secondly, we calculate water balances and relate them to the water quota system. We employed the remote sensing method Simplified Surface Energy Balance Index (S-SEBI), in order to map ET a based on MODIS satellite images for the growing seasons 2009, 2010, and 2011. Thereby, the MODIS products 8-day land surface temperature (MOD11A2), 16-day albedo (MCD43A3), and 16-day NDVI (MOD13A1) were used. The ET a of cotton ranges from 884 to 1198 mm. The ET a of the natural vegetation of a total coverage ranges from 715 in 2009 to 960 mm in 2011, clearly following the annual runoff of the Aksu and Tarim River. The water balance of the Aksu-Tarim river basin is −3.25 to −3.73 km 3 , 0.1–0.53 km 3 , and −3.55 to −4.12 km 3 in 2009, 2010, and 2011, respectively. The water quotas along the Aksu River and the upper reaches of the Tarim are exceeded by water consumption, while the quotas along the middle and lower reaches are not met. Considerable amounts of groundwater, including fossil groundwater, are exploited for irrigation along the Aksu and Tarim River, which must be regarded as exploitation of a non-renewable resource. [ABSTRACT FROM AUTHOR]

Since the Achaemenid Empire in 532-332 BCE, the 'Qanat' became the central irrigation system in the arid and semi-arid lands. Several terms are used for 'Qanat' in different regions, including the Karez, Qanat, Falaj type Daudi, Qanat Romani, Fuqara (Foggara), or Khettara as known in Central Asia, Persia, Southeast Arabia, Levant, North Africa, or Morocco respectively. Typically, the ground, spring or surface water (i.e. seasonal floods or river-fed) sources feed similar irrigation system. Based on thirteen years of extensive survey and analysis work (i.e. Sinai Peninsula Research 2000-2013 CE), this paper presents a rediscovered-new Qanat system in the High Mountains of Sinai Peninsula (i.e. UNESCO World Heritage Site 'WHS' no. 954) under chronological open question with Levantine reflections. In 1970s CE, the present Sinaitic site of Farsh Abu A'lwan or the anciently known Farsh Shamma'a was archaeologically surveyed without a direct reference to the Qanat system in-situ. Scientifically, it is an argumentative and unique Qanat system in terms of chronology, location (region), site (local-setting), water source, size and household utility. It is the only discovered 'Qanat' across the Sinai, connecting the Near East and North Africa. [ABSTRACT FROM AUTHOR]

Located in the hinterland of the Eurasian continent, the inland areas of northwestern China have an arid climate and are confronted with continuing challenges in water resources quantity and quality. Reclaimed water plays an important role in maintaining the sustainable use of urban water resources, especially in arid regions. In this paper, a system dynamics urban reclaimed water model (SDURWM) considering the status of arid regions in northwestern China was constructed. The supply and demand balance index (RWB) and the utilization efficiency index (RWUE) of reclaimed water were proposed as evaluation indicators. The potential of reclaimed water utilization (2016–2025) in three typical cities with similar natural environments and population sizes but with large economic differences were estimated by the SD model. Then the relevant values of reclaimed water quota, supply and resident awareness were adjusted within the range of 10%–20%. The predicted results from intervention demonstrate that the RWB of three cities will be closer or maintain to the ideal value, and that the RWUE will increase by about 0.1, compared with the non-intervention results. This indicates that a minor change of the targeted policies can invigorate the capacity of reclaimed water use in droughty cities. This paper provides some effective solutions for the government's planning of developing the potential of reclaimed water. • Established a SD model for urban reclaimed water utilization in arid areas. • Proposed RWB and RWUE for evaluating the comprehensive utilization potential of reclaimed water. • Explored targeted measures to improve the utilization of reclaimed water in typical arid cities of northwest China. [ABSTRACT FROM AUTHOR]

Abstract: In many parts of the world the boundaries between grassland and shrubland biomes have changed substantially over the course of the last century. Many are projected to shift further from being grass-dominated to shrub-dominated by 2050 under global climate change and land use change projections. This paper used long-term surveys and repeat photography to assess vegetation change at the shrubland-grassland ecotone in semi-arid, South Africa. Changes in several climate variables as well as in the cover of grasses and dwarf shrubs over three time periods (1962, 1989 and 2009) were investigated at eight localities within a broad 500 km ecotone between the Grassland and Nama-karoo biomes. Results showed that for most sites grass cover has increased and that dwarf shrub cover has decreased over time. This contradicts earlier views which warned against the expansion of dwarf shrublands in response to over-grazing as well as more recent views which suggest that more mesic biomes in the Karoo Midlands will contract in response to climate-induced aridification. The decline in stocking densities and more conservation-friendly land management practices together with an increase in large wet events in the Nama-karoo biome may have contributed to the increase in grass cover. [Copyright &y& Elsevier]

In the arid and semi-arid regions of the southeast of Spain, the low availability of water for irrigation requires the development of new water-conserving irrigation techniques. This leads to the use of precision agriculture technologies that permit an improvement in performance or reductions in the consumption of water and fertilisers. In this context, the use of digital photography enables plant growth monitoring, which allows crop water requirements to be determined from variables that are directly related to evapotranspiration. One of these variables is the percentage of ground cover, which has also been correlated with plant height. This paper presents a new method based on computer vision for estimating the crop coefficient (K c) of lettuce crops from the percentage of ground cover (PGC) extracted from digital photographs. In contrast to other methods reported in the literature, plant height (h) is estimated first; then, the term PGC/h is correlated with K c. The method was successfully applied to and validated using a commercial crop of lettuce (Lactuca sativa L. cv. ‘Hierro’) located in the southeast of Spain. [ABSTRACT FROM AUTHOR]

Abstract: Mediterranean environments are typical of semi-arid regions, dominated by episodes of torrential rain in which the critical variable is not the total rainfall, but the intensity. This paper studies the maximum rainfall intensities at different observation time scales, from 5 min to 24 h, over eastern Spain from 1994 to 2007. The statistical rainfall characteristics for each time scale are analysed and the effects of specific geographical factors – altitude, aspect and distance to the sea – for each observation interval are tested. The results show that extreme intensities are heavily dependent on the time scale. There are two important turning points in this trend, at 1 h and 6 h. With regard to the influence of geographical factors, distance from the sea is particularly important as it is significant for almost all observation time scales. Altitude is only significant between time scales of 30 min and 6 h. Aspect is not significant. Two intensity patterns are also observed: the first includes the highest intensities, at altitudes from 200 to 400 m and at locations 20–30 km from the sea, while the second is related to lower intensities, higher altitudes (900–1000 m) and longer distances to the sea (90–100 km). [Copyright &y& Elsevier]

Abstract: Degradation in arid rangelands is an on-going concern, as they appear to be trapped in a vicious circle of desertification–marginalization–impoverishment. Recent theoretical developments in dryland research strive to provide keys to understanding linked social-ecological systems and land management. One approach, the desert-syndrome, depicts the socio-ecological evolution of drylands as being determined mainly by ecological factors. A second approach, the adaptive management paradigm, acknowledges the existence of socio-ecological systems in drylands which are considered to have adapted to a given political–economic context and a given range of economic and ecological variability. This paper proposes a conceptual framework integrating both approaches in order to point out supplementary important drivers of the socio-ecological evolution of drylands systems, especially rangelands at the global economic and political scale. The analysis is broadly conducted from a political ecology and co-evolutionary perspectives and discusses three main factors: (1) world-wide application of western-based paradigms in resource management and their effect on rangelands, (2) the fossil-fuel based Green Revolution, and (3) capitalist institutions used to regulate agricultural trade and the corresponding tools and policies. The marginalization of arid rangelands is avoidable, but requires real changes in the current general political and economic rationale under which resources are allocated. [Copyright &y& Elsevier]

Abstract: We describe in this paper a traditional charcoal making technology occasionally adopted by Tuareg people in the hyper-arid central Sahara (SW Libya). This methodology (called esed) has been identified thanks to ethnobotanic and ethnographic interviews with people living in the Tadrart Acacus massif (the kel Tadrart Tuareg) and confirmed by macroscopic and micromorphological analyses of residual field evidence. Esed consisted of burning in situ trunks of dead Acacia tortilis (Forssk.) Hayne; subsequently, small portions of collapsed and still-burning wood were buried with sand in an attempt to ensure combustion under anoxic conditions. Our interviews elucidated that the esed technology is well known by people living in the region and has possibly been practiced for a long time. Surprisingly, local informants highlighted that esed was employed to made charcoal only during years marked by abrupt reduction of precipitation and consequently of natural resources. The last employment of esed dates to the dry phase of the mid-1970s, when charcoal was used as an exchangeable good. The discovery of this charcoal making technology shed new light on the capability of Tuareg to manage the few natural resources available in marginal environments and to cope with rapid climate changes. [Copyright &y& Elsevier]

Abstract: Recurrent droughts in arid and semi-arid regions are already rendering agricultural production, mainstay of subsistence livelihoods, uncertain. In order to mitigate the impact of drought, agricultural organizations must increase their capacity to adapt. Institutional adaptation refers to the creation of an effective, long-term government institution or set of institutions in charge of planning and policy, and its capacity to develop, revise, and execute drought policies. Using the Fars Agricultural Organization in Iran, as a case study, this paper explores the institutional capacities and capabilities, necessary to adapt to the drought conditions. The STAIR model was used as a conceptual tool, and the Bayesian network and Partial Least Squares (PLS) path modeling was applied to explain the mechanisms by which organizational capacities influence drought management. A survey of 309 randomly selected managers and specialists indicated serious weaknesses in the ability of the organization to apply adaptation strategies effectively. Analysis of the causal models illustrated that organizational culture and resources and infrastructure significantly influenced drought management performance. Moreover, managers and specialists perceived human resources and strategy, goals, and action plan, respectively, as the main drivers of institutional adaptation to drought conditions. Recommendations and implications for drought management policy are offered to increase organizational adaptation to drought and reduce the subsequent sufferings. [Copyright &y& Elsevier]

In a recent paper, Benson and Grimstead (2019) determined that only minimal amounts of maize could have been grown in Chaco Canyon due to its aridity, short growing season, and frequent summer flooding of the valley floor. In this paper it is shown that deer and rabbit densities within semiarid regions such as the Canyon are such that 2300 Canyon residents would eliminate essentially all small and large mammals within a year. This implies that food (meat and maize) must have been imported from one or more outlying areas to feed the Canyon's residential population. This would have entailed ~18,000 annual trips to the Canyon by porters carrying 45 kg. Although some Sr-isotope data on archaeofauna and maize recovered from Chaco match Sr-isotope values of soil extracts collected in the Canyon (Benson, 2010, 2012; Grimstead et al., 2016), the Canyon's low mammal densities and poor agricultural potential led to a search for other food-source areas with matching Sr-isotope ranges. New isotopic data indicated that the Chuska mountain region appears to be a primary source of these materials. However, there are also a number of other high-elevation relatively wet regions on the periphery of the San Juan Basin with soils having Sr-isotope values that match Chaco Canyon archaeofaunal values, especially values obtained on deer. • Low mammal densities in Chaco could not supply enough meat to feed 2300 residents. • 87Sr/86Sr data suggest archaeofauna came mainly but not only from the Chuskas. • In order to feed 2300 Chaco residents, porters carrying 44 kg must make 18,000 annual trips. [ABSTRACT FROM AUTHOR]

Abstract: The analysis of dietary traits of ungulates through tooth microwear and mesowear has been applied to archaeological sites to investigate seasonal changes in settlements by hunter–gatherers. In this paper we propose to test the hypothesis that tooth microwear (combined to mesowear) is able to indicate seasonality in the diet of extant ungulates in arid habitats (semi-deserts or steppe). The material analyzed comes from six faunal monospecific assemblages of guanaco (Lama guanicoe) resulting from a mass mortality event in winter 2000 near the Cardiel Lake in Southern Patagonia (Province of Santa Cruz, Argentina). Mesowear results indicate that the guanacos from the Cardiel Lake area are mixed feeders, and thus, have a diet that shifts seasonally. Moreover, microwear analysis supports the hypothesis that tooth microwear is able to indicate seasonality in the diet of extant guanaco in arid habitats. The pattern is clear for the winter sample and needs to be confirmed for a summer sample. Consequently, tooth microwear is proposed as a new potential proxy for detecting seasonal occupation in archaeological sites in Patagonia and other arid environments. [Copyright &y& Elsevier]

Abstract: This review is concerned with the aeolian geomorphology of the Namib Sand Sea, part of the Namib Desert in Namibia, south-west Africa, concentrating in particular on studies made over the past 50 years. The paper covers: sand sea organisation and dune patterns; and the dynamics of individual dunes. It demonstrates that studies in the Namib Sand Sea have been important to a much wider understanding of the geomorphological development of global sand seas. [Copyright &y& Elsevier]

Abstract: Carbon stocks and carbon accumulation in the earth''s drylands have gained increasing attention. The winter-cold deserts of Middle Asia, i.e. in Kazakhstan, Uzbekistan, and Turkmenistan, cover an area of 2.5 million km2. Within these deserts, the two Saxaul species White Saxaul (Haloxylon persicum Bunge ex Boiss. & Buhse) and Black Saxaul (Haloxylon aphyllum (Minkw.) Iljin) are dominant woody species with a potential distribution area of about 500,000 km2. From the 1950s until today, the Saxaul vegetation has been degraded through logging and over-grazing. In this paper, we estimate the current and potential living above ground and below ground biomass of the Saxaul vegetation and its carbon stock. The living above ground biomass ranges between 1.5 t/ha and 3 t/ha. The potential carbon stocks above ground and below ground amount to 29.4–52.1 million t and 22–81.4 million t, respectively. Today, only 11%–28% of the potential biomass and carbon stock have remained. The carbon stock of the Saxaul vegetation is low compared to other ecosystems of the earth, but restoration and conservation of Saxaul vegetation is one way to sequester carbon through vegetation for Uzbekistan and Turkmenistan, which do not have much other woody vegetation. [Copyright &y& Elsevier]

Surface water is one of the constraining resources for herbivore populations in semi-arid regions. Artificial waterpoints are constructed by wildlife managers to supplement natural water supplies, to support herbivore populations. The aim of this paper is to analyse how a landowner may realize his ecological and economic goals by manipulating waterpoints for the management of an elephant population, a water-dependent species in the presence of water-independent species. We develop a theoretical bio-economic framework to analyse the optimization of wildlife management objectives (in this case revenue generation from both consumptive and non-consumptive use and biodiversity conservation), using waterpoint construction as a control variable. The model provides a bio-economic framework for analysing optimization problems where a control has direct effects on one herbivore species but indirect effects on the other. A landowner may be interested only in maximization of profits either from elephant offtake and/or tourism revenue, ignoring the negative effects that could be brought about by elephants to biodiversity. If the landowner does not take the indirect effects of waterpoints into consideration, then the game reserve management, as the authority entrusted with the sustainable management of the game reserve, might use economic instruments such as subsidies or taxes to the landowners to enforce sound waterpoint management. [Copyright &y& Elsevier]