Climate change and human lakeside adaptation in the Central Afar Region (Lake Abhe basin, Ethiopia & Djibouti) during the Later Stone Age - Neolithic transition: a multi-scalar and multi-proxy approach

Throughout the last 20 ka, tropical Africa was the site of significant hydrological changes related to variations in the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that gradual long-term monsoon humid oscillations (African Humid Period ~14 &#8211; ~6 ka) were punctuated by centennial-scale episodes of hyperaridity (HS1, YD, 8.2 ka, 4.2 ka). These abrupt hydrological changes could have caused drastic transformations in landscape patterns, providing favourable ecosystems, but also produced arid environments that may have restricted human exploitation of the landscape.The Abhe Lake basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater and terrigenous inputs from the Ethiopian Highlands, and is a hydro-sedimentary system sensitive to hydroclimatic change. Since 2014, in the context of the VAPOR-Afar and PSPCA programs (in Ethiopia and Djibouti respectively), we have intensified scientific investigations over this basin with the objective of exploring the evolution of Holocene hydroclimatic change, its impact on landscapes and on prehistoric human behaviour during one of the most forcible transitions in human history, that from a dominantly hunter-gathering way of life to the food production societies one.We present the first results of this research that combines paleoclimatological, geomorphological and geoarchaeological studies based on a new set of 14C datations on two lacustrine cores, on several morpho-sedimentary outcrops and on 8 new archaeological sites spanning the Early to Late Holocene. Our results allow us to: a) refine the temporal occurrence and the modalities of the African Humid Period and of the 8.2 and 4.2 ka hyperarid episodes, coupling paleolake-level reconstitution and lacustrine sediment analysis (paleolimnology, geochemistry); b) evaluate the impact of these hydroclimatic oscillations on perilacustrine sedimentary formation processes, especially for pedogenic formations; c) and better understand the relationship between environmental change and the development of one of the most important economic and cultural innovations, that of domestication. &#160;

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Hydro-climatic fluctuations and their impact on Lake Abhe environments (Ethiopia & Djibouti): a lesson from the past 10,000 years

10.5194/egusphere-egu21-4634 ◽

2021 ◽

Author(s):

Carlo Mologni ◽

Laurent Bruxelles ◽

Fabien Arnaud ◽

Pierre Sabatier ◽

Anne-Lise Develle ◽

...

Keyword(s):

East African ◽

Climatic Fluctuations ◽

Climatic Oscillations ◽

Sedimentary Records ◽

Hydrological Changes ◽

Precession Cycle ◽

Afar Region ◽

Geomorphic Features ◽

Sedimentary System ◽

The Impact

Throughout the last 14 ka, tropical Africa experienced significant hydrological changes that were mainly driven by the orbital precession cycle, which controls the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that long-term monsoon humid oscillations (African Humid Period / AHP ~14 &#8211; ~6 ka) were punctuated by centennial-scale episodes of hyperaridity. However, the abrupt or gradual aridification modalities since the end of the AHP and the modalities of the centennial-scale episodes, as well as their impacts on past and current environments are still debated.The Lake Abhe basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater originating in the Ethiopian Highlands, and represents a hydro-sedimentary system sensitive to hydro-climatic changes in East Africa. Today it is characterized by residual lakes (Gamari and Afambo lakes) and a hyper-arid climate, while during the AHP, the Abhe basin was occupied by a Mega-lake and by humid environmental conditions. Holocene climatic disruptions drastically changed the landscapes and ways of life along this basin.&#160;&#160;The aim of this study is to describe, interpret and estimate the impact of hydro-climatic oscillations on the evolution of Lake Abhe&#8217;s littoral lacustrine environments and palaeolandscapes since the AHP from different viewpoints.Indeed, this research combines paleoclimatological and geomorphological studies based on a new set of 14C ages on two lacustrine cores and on several morpho-sedimentary outcrops spanning the Early to Late Holocene. Our results allow us to: a) refine the temporal occurrence and the hydrological modalities of the AHP including short-term arid episodes linked to Younger Dryas and 8.2 ka North Atlantic events; b) recognise some paleo-shoreline geomorphic features linked to lake level fluctuations, as well as the development littoral pedological horizons and the activation/shutdown of the perilacustrine fluvial network during humid and arid events; c) track these changes until the present day, and discuss their evolution scenario in the near future.Comparing with other regional climatic records, we show how Lake Abhe basin was highly reactive to East African monsoonal regimes, and how current hydrological changes could impact its environments.&#160; &#160;&#160;&#160;&#160;

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Carbon Dynamics in the Northeastern Qinghai–Tibetan Plateau from 1990 to 2030 Using Landsat Land Use/Cover Change Data

Remote Sensing ◽

10.3390/rs12030528 ◽

2020 ◽

Vol 12 (3) ◽

pp. 528 ◽

Cited By ~ 1

Author(s):

Jingye Li ◽

Jian Gong ◽

Jean-Michel Guldmann ◽

Shicheng Li ◽

Jie Zhu

Keyword(s):

Land Use ◽

Tibetan Plateau ◽

Carbon Storage ◽

Sharp Decrease ◽

Total Carbon ◽

Qinghai Lake ◽

Lake Basin ◽

Ecosystem Carbon ◽

Trade Offs ◽

The Impact

Land use/cover change (LUCC) has an important impact on the terrestrial carbon cycle. The spatial distribution of regional carbon reserves can provide the scientific basis for the management of ecosystem carbon storage and the formulation of ecological and environmental policies. This paper proposes a method combining the CA-based FLUS model and the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model to assess the temporal and spatial changes in ecosystem carbon storage due to land-use changes over 1990–2015 in the Qinghai Lake Basin (QLB). Furthermore, future ecosystem carbon storage is simulated and evaluated over 2020–2030 under three scenarios of natural growth (NG), cropland protection (CP), and ecological protection (EP). The long-term spatial variations in carbon storage in the QLB are discussed. The results show that: (1) Carbon storage in the QLB decreased at first (1990–2000) and increased later (2000–2010), with total carbon storage increasing by 1.60 Tg C (Teragram: a unit of mass equal to 1012 g). From 2010 to 2015, carbon storage displayed a downward trend, with a sharp decrease in wetlands and croplands as the main cause; (2) Under the NG scenario, carbon reserves decrease by 0.69 Tg C over 2020–2030. These reserves increase significantly by 6.77 Tg C and 7.54 Tg C under the CP and EP scenarios, respectively, thus promoting the benign development of the regional ecological environment. This study improves our understanding on the impact of land-use change on carbon storage for the QLB in the northeastern Qinghai–Tibetan Plateau (QTP).

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Mixed NNLO QCD×electroweak corrections of $$ \mathcal{O} $$(Nfαsα) to single-W/Z production at the LHC

Journal of High Energy Physics ◽

10.1007/jhep12(2020)201 ◽

2020 ◽

Vol 2020 (12) ◽

Author(s):

Stefan Dittmaier ◽

Timo Schmidt ◽

Jan Schwarz

Keyword(s):

Z Bosons ◽

Leading Order ◽

Current Standard ◽

Gauge Invariant ◽

Mass Distributions ◽

Self Energy ◽

Electroweak Gauge Boson ◽

First Results ◽

Invariant Part ◽

The Impact

Abstract First results on the radiative corrections of order $$ \mathcal{O} $$ O (Nfαsα) are presented for the off-shell production of W or Z bosons at the LHC, where Nf is the number of fermion flavours. These corrections comprise all diagrams at $$ \mathcal{O} $$ O (αsα) with closed fermion loops, form a gauge-invariant part of the next-to-next-to-leading-order corrections of mixed QCD×electroweak type, and are the ones that concern the issue of mass renormalization of the W and Z resonances. The occurring irreducible two-loop diagrams, which involve only self-energy insertions, are calculated with current standard techniques, and explicit analytical results on the electroweak gauge-boson self-energies at $$ \mathcal{O} $$ O (αsα) are given. Moreover, the generalization of the complex-mass scheme for a gauge-invariant treatment of the W/Z resonances is described for the order $$ \mathcal{O} $$ O (αsα). While the corrections, which are implemented in the Monte Carlo program Rady, are negligible for observables that are dominated by resonant W/Z bosons, they affect invariant-mass distributions at the level of up to 2% for invariant masses of ≳ 500 GeV and are, thus, phenomenologically relevant. The impact on transverse-momentum distributions is similar, taking into account that leading-order predictions to those distributions underestimate the spectrum.

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Cooling Efficiencies of a NiTi-Based Cooling Process

Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation and Control of Adaptive Systems; Integrated System Design and Implementation ◽

10.1115/smasis2013-3249 ◽

2013 ◽

Cited By ~ 6

Author(s):

Marvin Schmidt ◽

Andreas Schütze ◽

Stefan Seelecke

Keyword(s):

Solid State ◽

Thermodynamic Analysis ◽

Cooling System ◽

Analysis Method ◽

Efficiency Ratio ◽

Cooling Process ◽

First Results ◽

Work Input ◽

Underlying Mechanisms ◽

The Impact

Energy saving and environmental protection are topics of growing interest. In the light of these aspects alternative refrigeration principles become increasingly important. Shape memory alloys (SMA), especially NiTi alloys, generate a large amount of latent heat during solid state phase transformations, which can lead to a significant cooling effect in the material. These materials do not only provide the potential for an energy-efficient cooling process, they also minimize the impact on the environment by reducing the need for conventional ozone-depleting refrigerants. Our paper, presenting first results obtained in a project within the DFG Priority Program SPP 1599 “Ferroic Cooling”, focuses on the thermodynamic analysis of a NiTi-based cooling system. We first introduce a suitable cooling process and subsequently illustrate the underlying mechanisms of the process in comparison with the conventional compression refrigeration system. We further introduce a graphical solution to calculate the energy efficiency ratio of the system. This thermodynamic analysis method shows the necessary work input and the heat absorption of the SMA in stress/strain- or temperature/entropy-diagrams, respectively. The results of the calculations underline the high potential of this solid-state cooling methodology.

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Response of Sensitive and Resistant Snap Bean Genotypes to Nighttime Ozone Concentration

Journal of the American Society for Horticultural Science ◽

10.21273/jashs04808-19 ◽

2020 ◽

Vol 145 (6) ◽

pp. 331-339

Author(s):

Kirsten L. Lloyd ◽

Donald D. Davis ◽

Richard P. Marini ◽

Dennis R. Decoteau

Keyword(s):

Leaf Age ◽

Acute Injury ◽

Yield Response ◽

Yield Losses ◽

Foliar Injury ◽

Snap Bean ◽

Stirred Tank Reactors ◽

First Results ◽

Significant Yield ◽

The Impact

Effects of nighttime (2000 to 0700 hr) O3 on the pod mass of sensitive (S156) and resistant (R123) snap bean (Phaseolus vulgaris) genotypes were assessed using continuous stirred tank reactors located within a greenhouse. Two concentration-response relationship trials were designed to evaluate yield response to nighttime O3 exposure (10 to 265 ppb) in combination with daytime exposure at background levels (44 and 62 ppb). Three replicated trials tested the impact of nighttime O3 treatment at means of 145, 144, and 145 ppb on yields. In addition, stomatal conductance (gS) measurements documented diurnal variations and assessed the effects of genotype and leaf age. During the concentration-response experiments, pod mass had a significant linear relationship with the nighttime O3 concentration across genotypes. Yield losses of 15% and 50% occurred at nighttime exposure levels of ≈45 and 145 ppb, respectively, for S156, whereas R123 yields decreased by 15% at ≈150 ppb. At low nighttime O3 levels of ≈100 ppb, R123 yields initially increased up to 116% of the treatment that received no added nighttime O3, suggesting a potential hormesis effect for R123, but not for S156. Results from replicated trials revealed significant yield losses in both genotypes following combined day and night exposure, whereas night-only exposure caused significant decreases only for S156. The gS rates ranged from less than 100 mmol·m−2·s−1 in the evening to midday levels more than 1000 mmol·m−2·s−1. At sunrise and sunset, S156 had significantly higher gS rates than R123, suggesting a greater potential O3 flux into leaves. Across genotypes, younger rapidly growing leaves had higher gS rates than mature fully expanded leaves when evaluated at four different times during the day. Although these were long-term trials, gS measurements and observations of foliar injury development suggest that acute injury, occurring at approximately the time of sunrise, also may have contributed to yield losses. To our knowledge, these are the first results to confirm that the relative O3 sensitivity of the S156/R123 genotypes is valid for nighttime exposure.

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Macro and microeconomic analysis of the impact of the covid-19 pandemic in Chile and the projections of the central bank's

International Research Journal of Management IT and Social Sciences ◽

10.21744/irjmis.v8n3.1471 ◽

2021 ◽

Vol 8 (3) ◽

Author(s):

Rodrigo Barra Novoa

Keyword(s):

Central Bank ◽

Medium Term ◽

Social Growth ◽

Representative Data ◽

First Approximation ◽

Microeconomic Analysis ◽

The Social ◽

First Results ◽

Business Profitability ◽

The Impact

This article offers a first approximation of the impacts of the COVID-19 pandemic on the Chilean macro and microeconomic environment, using representative data from the latest formal surveys in the country. Here, the number of active firms plummeted in part due to the social crisis that began on October 18, 2019, and losses were felt in most industries due to the pandemic crisis that continues to generate job losses and low business profitability. These first results have implications for central bank policies and can predict medium and medium-term projections, especially for the country's economic and social growth.

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Relating Land Use/Cover and Landscape Pattern to the Water Quality under the Simulation of SWAT in a Reservoir Basin, Southeast China

Sustainability ◽

10.3390/su131911067 ◽

2021 ◽

Vol 13 (19) ◽

pp. 11067

Author(s):

Kaige Lei ◽

Yifan Wu ◽

Feng Li ◽

Jiayu Yang ◽

Mingtao Xiang ◽

...

Keyword(s):

Water Quality ◽

Land Use ◽

Google Earth ◽

Landscape Patterns ◽

Buffer Size ◽

Construction Land ◽

Drinking Water Standard ◽

Reservoir Basin ◽

The Impact ◽

Cover Pattern

Understanding the relationship between land use/cover pattern and water quality could provide guidelines for non-point source pollution and facilitate sustainable development. The previous studies mainly relate the land use/cover of the entire region to the water quality at the monitoring sites, but the water quality at monitoring sites did not totally reflect the water environment of the entire basin. In this study, the land use/cover was monitored on Google Earth Engine in Tang-Pu Reservoir basin, China. In order to reflect the water quality of the whole study area, the spatial distribution of the determinants for water quality there, i.e., the total nitrogen and total phosphorus (TN&TP), were simulated by the Soil and Water Assessment Tool (SWAT). The redundancy analysis explored the correlations between land use/cover pattern and simulated TN&TP. The results showed that: (1) From 2009 to 2019, forest was the dominant land cover, and there was little land use/cover change. The landscape fragmentation increased, and the connectivity decreased. (2) About 25% TP concentrations and nearly all the TN concentrations at the monitoring points did not reach drinking water standard, which means nitrogen and phosphorus pollution were the most serious problems. The highest output per unit TN&TP simulated by SWAT were 44.50 kg/hm2 and 9.51 kg/hm2 and occurred in areas with highly fragile landscape patterns. (3) TN&TP correlated positively with cultivated and construction land but negatively with forest. The correlation between forest and TN&TP summited at 500–700-m buffer and construction land at 100-m buffer. As the buffer size increased, the correlation between the cultivated land, and the TN weakened, while the correlation with the TP increased. TN&TP correlated positively with the Shannon’s Diversity Index and negatively with the Contagion Index. This study provides a new perspective for exporting the impact of land use/cover pattern on water quality.

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Seismostratigraphic Interpretation of Upper Cretaceous Reservoir from the Carpathian Foreland, Southern Poland

Energies ◽

10.3390/en14227776 ◽

2021 ◽

Vol 14 (22) ◽

pp. 7776

Author(s):

Andrzej Urbaniec ◽

Anna Łaba-Biel ◽

Anna Kwietniak ◽

Imoleayo Fashagba

Keyword(s):

Late Cretaceous ◽

Upper Cretaceous ◽

Tectonic Setting ◽

Small Scale ◽

Reservoir Properties ◽

Southern Poland ◽

Seismic Sequence Stratigraphy ◽

First Results ◽

Depositional Architecture ◽

The Impact

The Upper Cretaceous complex in the central part of the Carpathian Foreland (southern Poland) is relatively poorly recognized and described. Its formations can be classified as unconventional reservoir due to poor reservoir properties as well as a low recovery factor. The main aim of the article is to expand knowledge with conclusions resulting from the analysis of the latest seismic data with the application of seismic sequence stratigraphy. Moreover, the seismic attributes analysis was utilized. The depositional architecture recognition based on both chronostratigraphic horizons and Wheeler diagram interpretations was of paramount importance. A further result was the possibility of using the chronostratigraphic image for tectonostratigraphic interpretation. Two distinguished tectonostratigraphic units corresponding to megasequences were recognized. A tectonic setting of the analyzed interval is associated with global processes noticed by other authors in other parts of the central European Late Cretaceous basin, but also locally accompanied by evidence of small-scale tectonics. This study fills the gap on the issue of paleogeography in the Late Cretaceous sedimentary basin of the Carpathian Foreland. It presents the first results of detailed reconstruction of the basin paleogeography and an attempt to determine the impact of both eustatic and tectonic factors on sedimentation processes.

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Desiccation-crack-induced salinization in deep clay sediment

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-9-13155-2012 ◽

2012 ◽

Vol 9 (11) ◽

pp. 13155-13189

Author(s):

S. Baram ◽

Z. Ronen ◽

D. Kurtzman ◽

C. Küells ◽

O. Dahan

Keyword(s):

Isotopic Composition ◽

Conceptual Model ◽

Pore Water ◽

Vadose Zone ◽

Land Surface ◽

Water Infiltration ◽

Arid Environments ◽

Desiccation Cracks ◽

The Impact ◽

Desiccation Crack

Abstract. A study on water infiltration and solute transport in a clayey vadose zone underlying a dairy farm waste source was conducted to assess the impact of desiccation cracks on subsurface evaporation and salinization. The study is based on five years of continuous measurements of the temporal variation in the vadose zone water-content and on the chemical and isotopic composition of the sediment and pore-water in it. The isotopic composition of water stable isotopes (δ18O and δ2H) in water and sediment samples, from the area where desiccation crack networks prevail, indicated subsurface evaporation down to ∼3.5 m below land surface, and vertical and lateral preferential transport of water, following erratic preferential infiltration events. Chloride (Cl-) concentrations in the vadose zone pore water substantially increased with depth, evidence of deep subsurface evaporation and down flushing of concentrated solutions from the evaporation zones during preferential infiltration events. These observations led to development of a Desiccation-Crack-Induced Salinization (DCIS) conceptual model. DCIS suggests that thermally driven convective air flow in the desiccation cracks induces evaporation and salinization in relatively deep sections of the subsurface. This conceptual model supports previous conceptual models on vadose zone and groundwater salinization in fractured rock in arid environments and extends its validity to clayey soils in semi-arid environments.

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Riparian Vegetation Dynamic and River Stability on Intermittent Rivers: Impact of Water Transfer Project on Tropical Drylands

10.5194/egusphere-egu21-13485 ◽

2021 ◽

Author(s):

Camilla Santos ◽

Leonardo Dantas Martins ◽

Kenia Sousa da Cruz ◽

Jonas Otaviano Praça de Souza

Keyword(s):

Vegetation Cover ◽

Riparian Vegetation ◽

Google Earth ◽

Water Transfer ◽

Lateral Stability ◽

Hydrological Changes ◽

Vertical Incision ◽

Short Period ◽

Geomorphic Units ◽

The Impact

Rivers on semiarid landscapes typically are characterised by sandy geomorphic units and riverbanks, a natural factor that enhances lateral mobility. Vegetation cover is a crucial factor on lateral instability due to its impact on riverbank and geomorphic units erosion resistance. Nevertheless, riparian vegetation on intermittent and ephemeral channels show growing patterns directly affect by the flow temporality, that controls the water availability. Extended dry intervals hinder the succession ecological on geomorphic units, like bars and islands, and riverbanks and retard the growing process. This work analysed the effects of hydrological changes, caused by one water transfer project, on the bio-geomorphological patterns on riverbanks of a main intermittent river of Brazilian Drylands. Flow data series was used to understand the hydrological pattern changes; Google Earth images and UAV surveys to analyse the vegetation and riverbank behaviour from 2008 to 2020.&#160; Lastly, the identification of riverbank material resistance was based on sedimentology analysis. &#160;The water transfer Project PISF (Projeto de Integra&#231;&#227;o do S&#227;o Francisco), operating since 2017 March, increase the average flow days from 137,5 to 260/300 days and decreasing the continuous dry period from 200 to 30/45 days. The impact on average annual discharge was slightest, whereas the average water transfer volume was 3m3/s. It is essential to highlight the short period of data posterior to the water transfer and the non-regulatiry of water volume transferred; what limits the temporal representativity of the results. There were different types, and level of impacts depending on the river reach characteristics. However, in general, the longer flow permanence increases riparian vegetation density, vertical incision, and lateral stability. Riparian vegetation cover increase, from 20% to 100% on the 9 reaches analysed, across the entire channel, including bedrock reaches, with riverbanks having some rock outcrops percentage. The main changes were on sand bed reaches, that used to have, before 2017, a dynamic braiding pattern, without a clear main incised channel and thalweg shifting. Afterwards, the flow permanence, due to the water transfer project, enabled herbaceous stratus temporal continuity, contributing to surface stability and progressive bushes/trees cover growing. Lastly, the increase in lateral stability, mainly on thalweg position, facilitates the vertical incision on the sand bed reaches, representing 85% of this channel. As a secondary impact, there were necessary, to the road network, built floodway crossings at several points, which changes the channel morphology and the (dis)connectivity process. It can generate distinct channel position and morphology changes causing water and sediment retention upstream and erosion downstream. Lastly, there were slight differences in textural characteristics on riverbanks and geomorphic units, with a rise in fine sediment on the most vegetated areas/units. This analysis reveals that a fast response of riparian vegetation and sand bed reaches morphology, affecting the bio-geomorphological process and all environmental dynamic. It points to fundamental elements which need monitoring after hydrological changes, especially to intermittent and ephemeral rivers.

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