scholarly journals 501 Years of Spring Precipitation History for the Semi-Arid Northern Iran Derived from Tree-Ring δ18O Data

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 889
Author(s):  
Zeynab Foroozan ◽  
Jussi Grießinger ◽  
Kambiz Pourtahmasi ◽  
Achim Bräuning
Keyword(s):  
Tree Ring ◽  
Large Scale ◽  
Major Influence ◽  
World Knowledge ◽  
Spring Precipitation ◽  
Northern Iran ◽  
Climate Conditions ◽  
Atmospheric Circulation Indices ◽  
The Impact ◽  
Semi Arid

In semi-arid regions of the world, knowledge about the long-term hydroclimate variability is essential to analyze and evaluate the impact of current climate change on ecosystems. We present the first tree-ring δ18O based hydroclimatic reconstruction for northern semi-arid Iran spanning the period 1515–2015. A highly significant correlation between tree-ring δ18O variations of juniper trees and spring (April–June) precipitation reveals a major influence of spring water availability during the early growing season. The driest period of the past 501 years occurred in the 16th century while the 18th century was the wettest, during which the overall highest frequency of wet year events occurred. A gradual decline in spring precipitation is evident from the beginning of the 19th century, pointing to even drier climate conditions. The analysis of dry/wet events indicates that the frequency of years with relatively dry spring increased over the last three centuries, while the number of wet events decreased. Our findings are in accordance with historical Persian disaster records (e.g., the severe droughts of 1870–1872, 1917–1919; severe flooding of 1867, the 1930s, and 1950). Correlation analyses between the reconstruction and different atmospheric circulation indices revealed no significant influence of large-scale drivers on spring precipitation in northern Iran.

A multi-century spring precipitation history for northern Iran derived from tree-ring δ18O 

2021 ◽  
Author(s):  
Zeynab Foroozan ◽  
Jussi Grießinger ◽  
Kambiz Pourtahmasi ◽  
Achim Bräuning
Keyword(s):  
Tree Ring ◽  
Large Scale ◽  
Regional Climate ◽  
Spring Precipitation ◽  
Northern Iran ◽  
The Past ◽  
Precipitation Record ◽  
Hydroclimatic Variability ◽  
Semi Arid

<p>Knowledge about the long-term hydroclimatic variability is essential to analyze the historic course and recent impact of climate change, especially in semi-arid and arid regions of the world. In this study, we present the first tree-ring δ<sup>18</sup>O chronology for the semi-arid parts of northern Iran based on juniper trees. We were able to reconstruct past hydroclimatic variability for the past 500 years. The highly significant correlation between tree-ring δ<sup>18</sup>O and spring precipitation indicates the primary influence of spring moisture availability on δ<sup>18</sup>O variations. The thereof derived precipitation reconstruction reveals short and long-term variability of precipitation intensity, duration, and frequency of dry/wet events. During the past 500 years, the driest period occurred in the 16<sup>th</sup> century, whereas the 18th century was comparably wet. A gradual decline in the reconstructed spring precipitation is evident since the beginning of the 19th century, culminating in the continuing drought of the 20<sup>th</sup> century. An analysis of dry/wet years indicated that over the last three centuries, the occurrence of years with a relatively dry spring is increasing. In contrast, more humid spring conditions are decreasing. However, the overall frequency of the occurrence of extreme events increased over the past five centuries. In addition, past hydrological disasters recorded in Persian history were well represented in our reconstruction. Correlations between our reconstructed precipitation record and large-scale circulation systems revealed no significant influence of large-scale climatic drivers on spring precipitation variations in north Iran, which therefore seem to be mostly controlled by a regional climate forcing.</p>

scholarly journals External Groundwater Alleviates the Degradation of Closed Lakes in Semi-Arid Regions of China

2019 ◽  
Vol 12 (1) ◽  
pp. 45 ◽  
Author(s):  
Jiaqi Chen ◽  
Jiming Lv ◽  
Ning Li ◽  
Qingwei Wang ◽  
Jian Wang
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Isotopic Signature ◽  
Water Infiltration ◽  
Agricultural Irrigation ◽  
Lake Area ◽  
Daihai Lake ◽  
Huangqihai Lake ◽  
The Impact ◽  
Semi Arid

There are a large number of lakes with beaded distribution in the semi-arid areas of the Inner Mongolian Plateau, and some of them have degraded or even disappeared during the past three decades. We studied the reasons of the disappearance of these lakes by determining the way of replenishment of these lakes and the impact of the natural-social environment of the basin, with the aim of saving these gradually disappearing lakes. Based on remote sensing image and hydrological analysis, this paper studied the recharge of Daihai Lake and Huangqihai Lake. The deep learning method was used to establish the time-series of lake evolution. The same method was combined with the innovative woodland and farmland extraction method to set up the time-series of ground classification composition in the basins. Using relevant survey data, combined with soil water infiltration test, water chemical, and isotopic signature analysis of various water bodies, we found that the Daihai Lake area is the largest in dry season and the smallest in rainy season and the other lake is not satisfied with this phenomenon. In addition, we calculated the specific recharge and consumption of the study basin. These experiments indicated that the exogenous groundwater is recharged directly through the faults at the bottom of Daihai Lake, while the exogenous groundwater is recharged in Huangqihai Lake through rivers indirectly. Large-scale exploitation of groundwater for agricultural irrigation and industrial production is the main cause of lake degradation. Reducing the extraction of groundwater for agricultural irrigation is an important measure to restore lake ecology.

Genesis and Evolution of Black Soil in the Eastern Mediterranean

2020 ◽  
Author(s):  
Hussam Hag Mohamed Husein ◽  
Wahib Sahwan ◽  
Bernhard Lucke ◽  
Rupert Bäumler
Keyword(s):  
Eastern Mediterranean ◽  
Dead Sea ◽  
Black Soil ◽  
Parent Material ◽  
Climate Conditions ◽  
Lacustrine Deposits ◽  
Evolution And Development ◽  
Semi Arid Region ◽  
The Impact ◽  
Semi Arid

<p><strong>A</strong><strong>bstract</strong></p><p>Knowledge about the genesis and evolution of black soils in the Eastern Mediterranean is vital for sustainable land management as well as for revealing the current and past climate conditions that were decisive for their evolution and development. Hence, it is important to study this type of soil as it only occurs very rarely in the semi-arid region. Answers on the conditions of formation and type of paleoclimate that prevailed during its development can be found in the surrounding environment. In this study, the black soils that currently occur in the Eastern Mediterranean were analyzed in different bioclimatic zones and were found to genetically belong to two soil types: 1-Calcareous black soil (ProperRendzina-Typic Rendolls), 2-Hydromorphic black soil (Haploxerolls). The impact of the relief was obvious on both thickness of the solum and the mollic horizon. Proper Rendzina (Typic Rendolls) occurs on toe slopes and feet slopes, Para-Rendzina (Lithic Rendolls) on shoulders and Chernozems on a flat plain. Regarding the Rendzina, the color reflects the origin of the prevailing parent material from which they are derived: Proper Rendzina forms on limestone, chalk, sandstone, conglomerates, and claystone; Reddish Rendzina on Dolomite and hard limestone, and Grayish Rendzina on Serpentine. It was also found that the Hydromorphic black soils (Haploxerolls, Calcic Chernozems) only occur on calcic marl and lacustrine deposits under saturation conditions and bad drainage in the depressions that formed by the Dead Sea faults. The soil has a thick dark mollic horizon with a high content of organic matter.</p><p><strong>Keywords</strong>: semi-arid, black soil, Rendzina, Chernozems, eastern Mediterranean.</p><p> </p>

scholarly journals Multi-decadal river flow variations in France

2014 ◽  
Vol 18 (2) ◽  
pp. 691-708 ◽  
Author(s):  
J. Boé ◽  
F. Habets
Keyword(s):  
Soil Moisture ◽  
Large Scale ◽  
River Flow ◽  
Decadal Variability ◽  
Internal Variability ◽  
Spring Precipitation ◽  
Main Mode ◽  
River Flows ◽  
Decadal Variations ◽  
The Impact

Abstract. In this article, multi-decadal variations in the French hydroclimate are investigated, with a specific focus on river flows. Based on long observed series, it is shown that river flows in France generally exhibit large multi-decadal variations in the instrumental period (defined in this study as the period from the late 19th century to the present), especially in spring. Differences of means between 21 yr periods of the 20th century as large as 40% are indeed found for many gauging stations. Multi-decadal spring river flow variations are associated with variations in spring precipitation and temperature. These multi-decadal variations in precipitation are themselves found to be driven by large-scale atmospheric circulation, more precisely by a multi-decadal oscillation in a sea level pressure dipole between western Europe and the eastern Atlantic. It is suggested that the Atlantic Multidecadal Variability, the main mode of multi-decadal variability in the North Atlantic–Europe sector, controls those variations in large-scale circulation and is therefore the main ultimate driver of multi-decadal variations in spring river flows. Potential multi-decadal variations in river flows in other seasons, and in particular summer, are also noted. As they are not associated with significant surface climate anomalies (i.e. temperature, precipitation) in summer, other mechanisms are investigated based on hydrological simulations. The impact of climate variations in spring on summer soil moisture, and the impact of soil moisture in summer on the runoff-to-precipitation ratio, could potentially play a role in multi-decadal summer river flow variations. The large amplitude of the multi-decadal variations in French river flows suggests that internal variability may play a very important role in the evolution of river flows during the next decades, potentially temporarily limiting, reversing or seriously aggravating the long-term impacts of anthropogenic climate change.

scholarly journals Impacts of Large-Scale Open-Pit Coal Base on the Landscape Ecological Health of Semi-Arid Grasslands

2019 ◽  
Vol 11 (15) ◽  
pp. 1820 ◽  
Author(s):  
Zhenhua Wu ◽  
Shaogang Lei ◽  
Qingqing Lu ◽  
Zhengfu Bian
Keyword(s):  
Large Scale ◽  
Landscape Planning ◽  
Open Pit ◽  
Ecological Health ◽  
Gradual Decline ◽  
Temporal And Spatial ◽  
Arid Grasslands ◽  
Landscape Ecological ◽  
The Impact ◽  
Semi Arid

Coal is an important energy resource in the world, especially in China. Extensive coal exploitation seriously damaged the grassland and its fragile ecosystem. However, temporal and spatial impact laws of open-pit coal exploitation on Landscape Ecological Health (LEH) of semi-arid grasslands are still not clear. Therefore, the main objective of this paper is to study impact of Large-scale Open-pit Coal Base (LOCB) on the LEH of semi-arid grasslands from the perspectives of temporal and spatial. Taking Shengli LOCB of Xilinguole grassland in Inner Mongolia as an example, we demonstrate a conceptual model of LOCB impact on LEH of semi-arid grasslands, and establish a research system called landscape Index-pattern Evolution-Driving force-Spatial statistics (IEDS). A complete process integrated from investigation, monitoring, and evaluation to the analysis of impact laws was developed. Result indicated that coal mining causes gradual increase of landscape patches, landscape fragmentation, gradual decline of landscape connectivity, complexity and irregularity of landscape shape, enhancement of landscape heterogeneity and complexity, gradual decline of landscape stability, gradual decrease of grassland landscape and annual increase of unhealthy grassland landscape. The LEH of grassland basically belongs to the state of slight deterioration. In the past 15 years, the spatial and temporal distribution characteristics of LEH in the study area are similar. This study provides scientific reference for ecological disturbance research, environmental protection, landscape planning, restoration and renovation of ecological environment in mining areas. At the same time, future research should integrate geological, hydrological, soil, vegetation, microorganisms, animals, climate, and other perspectives to study the impact of mining on landscape ecology deeply.

scholarly journals Modelling Small-Scale Storage Interventions in Semi-Arid India at the Basin Scale

2021 ◽  
Vol 13 (11) ◽  
pp. 6129
Author(s):  
Robyn Horan ◽  
Pawan S. Wable ◽  
Veena Srinivasan ◽  
Helen E. Baron ◽  
Virginie J. D. Keller ◽  
...  
Keyword(s):  
Water Resource Management ◽  
Large Scale ◽  
Data Availability ◽  
Small Scale ◽  
Catchment Scale ◽  
Check Dams ◽  
Basin Scale ◽  
The Impact ◽  
Availability Assessment ◽  
Semi Arid

There has been renewed interest in the performance, functionality, and sustainability of traditional small-scale storage interventions (check dams, farm bunds and tanks) used within semi-arid regions for the improvement of local water security and landscape preservation. The Central Groundwater Board of India is encouraging the construction of such interventions for the alleviation of water scarcity and to improve groundwater recharge. It is important for water resource management to understand the hydrological effect of these interventions at the basin scale. The quantification of small-scale interventions in hydrological modelling is often neglected, especially in large-scale modelling activities, as data availability is low and their hydrological functioning is uncertain. A version of the Global Water Availability Assessment (GWAVA) water resources model was developed to assess the impact of interventions on the water balance of the Cauvery Basin and two smaller sub-catchments. Model results demonstrate that farm bunds appear to have a negligible effect on the average annual simulated streamflow at the outlets of the two sub-catchments and the basin, whereas tanks and check dams have a more significant and time varying effect. The open water surface of the interventions contributed to an increase in evaporation losses across the catchment. The change in simulated groundwater storage with the inclusion of interventions was not as significant as catchment-scale literature and field studies suggest. The model adaption used in this study provides a step-change in the conceptualisation and quantification of the consequences of small-scale storage interventions in large- or basin-scale hydrological models.

scholarly journals Reopening Schools and the Dynamics of SARS-CoV-2 Infections in Israel: A Nationwide Study

2021 ◽  
Author(s):  
Ido Somekh ◽  
Tamy Shohat ◽  
Lital Keinan Boker ◽  
Eric A F Simões ◽  
Eli Somekh
Keyword(s):  
Large Scale ◽  
Age Groups ◽  
Morbidity And Mortality ◽  
Major Influence ◽  
Nationwide Study ◽  
Social Distancing ◽  
Temporal Differences ◽  
Mortality Risks ◽  
The Impact

Abstract Background The benefits of school reopening must be weighed against the morbidity and mortality risks and the impact of enhancing spread of COVID-19. We investigated the effects of school reopening and easing of social distancing restrictions on the dynamics of SARS-CoV-2 infections in Israel, between March-July 2020. Methods We examined the nationwide agewise weekly incidence, prevalence, SARS-CoV-2 PCR tests, their positivity, COVID-19 hospitalizations and associated mortality. Temporal differences in these parameters following school reopening, school ending, and following easing of restrictions such as permission of large scale gatherings, were examined. Results The incidence of SARS-CoV-2 infections gradually increased following school reopening in all age groups, with a significantly higher increase in adults compared to children. Higher relative ratios (RRs) of sample positivity rates 21-27 days following school reopening relative to positivity rates prior to openings were found for the age groups 40-59 (RR: 4.72, 95% CI: 3.26 - 6.83) and 20-39 years (RR: 3.37 [2.51 - 4.53]), but not for children aged 0-9 (RR: 1.46 [0.85 - 2.51]) and 10-19 years (RR: 0.93 [0.65 - 1.34]). No increase was observed in COVID-19 associated hospitalizations and deaths following school reopening. In contrast, permission of large-scale gatherings was accompanied by increases in incidence and positivity rates of samples for all age groups, and increased hospitalizations and mortality. Conclusions This analysis does not support a major role of school reopening in the resurgence of the COVID-19 curve in Israel. Easing restrictions on large scale gatherings was the major influence on this resurgence.

scholarly journals Multi-decadal river flows variations in France

2013 ◽  
Vol 10 (9) ◽  
pp. 11861-11900 ◽  
Author(s):  
J. Boé ◽  
F. Habets
Keyword(s):  
Soil Moisture ◽  
Large Scale ◽  
Decadal Variability ◽  
Internal Variability ◽  
Historical Period ◽  
Spring Precipitation ◽  
Main Mode ◽  
River Flows ◽  
Decadal Variations ◽  
The Impact

Abstract. In this article, multi-decadal variations in French hydroclimate are investigated, with a specific focus on river flows. Based on long observed series, it is shown that river flows in France generally exhibit large multi-decadal variations on the historical period, especially in spring. Differences of means between two 21 yr periods of the 20th century as large as 40% are indeed found for many gauging stations. Multi-decadal spring river flows variations are associated with variations in spring precipitation and temperature. These multi-decadal variations in precipitation are themselves found to be driven by large-scale atmospheric circulation, more precisely by a multi-decadal oscillation in a sea level pressure dipole between western Europe and the East Atlantic. It is suggested that the Atlantic Multidecadal Variability, the main mode of decadal variability in the North Atlantic/Europe sector, controls those variations in large-scale circulation and is therefore the main ultimate driver of multi-decadal variations in spring river flows. Multi-decadal variations in river flows in other seasons, and in particular summer, are also noted. As they are not associated with significant surface climate anomalies (i.e. temperature, precipitation) in summer, other mechanisms are investigated based on hydrological simulations. The impact of climate variations in spring on summer soil moisture, and the impact of soil moisture in summer on the runoff to precipitation ratio, could potentially play a role in multi-decadal summer river flows variations. The large amplitude of the multi-decadal variations in French river flows suggests that internal variability may play a very important role in the evolution of river flows during the next decades, potentially temporarily limiting, reversing or seriously aggravating the long-term impacts of anthropogenic climate change.

scholarly journals Assessing the Impact of Land Cover, Soil, and Climate on the Storage Potential of Dryland Sand Dams

2021 ◽  
Vol 3 ◽  
Author(s):  
Jessica A. Eisma ◽  
Siddharth Saksena ◽  
Venkatesh Merwade
Keyword(s):  
Climate Change ◽  
Groundwater Recharge ◽  
Large Scale ◽  
Rainfall Variability ◽  
Performance Criteria ◽  
Intraseasonal Variation ◽  
Climate Conditions ◽  
Water Storage Capacity ◽  
Storage Potential ◽  
The Impact

Sand dams, a water-harvesting structure employed by rural communities in drylands have an inconsistent record of effectiveness. While many sand dams are highly functioning, improper siting, siltation, seepage, and high rates of evaporation from shallow sand reservoirs inhibit the water storage capacity of some sand dams. This study examines large-scale drivers of sand dam storage potential through analysis of an integrated surface and subsurface flow model. Multiple simulations were run, and comparative simulation analyses consider the effect of geomorphological factors, intraseasonal rainfall variability, and future climate conditions on sand dam performance criteria. The analyses revealed that a watershed highly cultivated with low water crops actually reduces evapotranspiration below that of natural vegetation and supports higher groundwater recharge. Additionally, intraseasonal variation and volume of rainfall impact sand dam performance less than the prevailing pattern and duration of dry and rainy seasons. Sand dams constructed in watersheds with sandier soils may experience greater connectivity with the stream margins and thus provide additional groundwater recharge. Lastly, climate change may improve some conditions desirable for sand dam performance, such as extending the duration of the rainy season and reducing overall evapotranspiration. However, the interactions between the expected climate change conditions and other geomorphological factors may result in a net decline in sand dam performance. The results of this study may help identify watersheds that are likely to support a sand dam with high potential for capturing and storing water throughout the dry season.

scholarly journals Spatiotemporal Analysis of Vegetation Cover in Kurdistan Region-Iraq using MODIS Image Data

2020 ◽  
Vol 1 (1) ◽  
pp. 01-07
Author(s):  
Yaseen Mustafa
Keyword(s):  
Large Scale ◽  
Image Data ◽  
Spatiotemporal Analysis ◽  
Major Influence ◽  
Kurdistan Region ◽  
Climate Conditions ◽  
North East ◽  
The North ◽  
West Part ◽  
Modis Image

The rapidly and wide use of remote sensing and accurately obtain information on the spatiotemporal distribution of large-scale vegetation is of great significance for improving and managing the Environment. To assess and analyze the spatiotemporal variation of vegetation status in Kurdistan Region of Iraq (KRGI), we used time series NDVI-based vegetation that are extracted from MOD13Q1 MODIS product over 20 years (2000 - 2019). The results showed that vegetation was mainly distributed in the north-east to south-east of the KRGI, while west region has less distributed and almost no vegetation. This is clearly remarkable in the south-west part of the region (Garmian administration). While, the most dominated vegetation province was Duhok province in KRGI during study period. There is a noticeable temporal variation in vegetation over a period of 20-year in the KRGI. The lower vegetated cover area is observed in the years 2000, 2008, and 2009. The increase/decrease of vegetated cover area is not only effected by climate conditions. The anthropogenic resource is also one of the main resources that has a major influence on the increase/decrease of vegetation.

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