LONG-TERM RECONSTRUCTION OF WATER LEVEL CHANGES FOR LAKE ATHABASCA BY ANALYSIS OF TREE RINGS

Author(s):  
Charles W. Stockton ◽  
Harold C. Fritts
2020 ◽  
Vol 46 (4) ◽  
pp. 813-823 ◽  
Author(s):  
Upendra Bhele ◽  
Burak Öğlü ◽  
Arvo Tuvikene ◽  
Priit Bernotas ◽  
Maidu Silm ◽  
...  

2011 ◽  
Vol 75 (3) ◽  
pp. 430-437 ◽  
Author(s):  
Liisa Nevalainen ◽  
Kaarina Sarmaja-Korjonen ◽  
Tomi P. Luoto

AbstractThe usability of subfossil Cladocera assemblages in reconstructing long-term changes in lake level was examined by testing the relationship between Cladocera-based planktonic/littoral (P/L) ratio and water-level inference model in a surface-sediment dataset and in a 2000-yr sediment record in Finland. The relationships between measured and inferred water levels and P/L ratios were significant in the dataset, implying that littoral taxa are primarily deposited in shallow littoral areas, while planktonic cladocerans accumulate abundantly mainly in deepwater locations. The 2000-yr water-level reconstructions based on the water-level inference model and P/L ratio corresponded closely with each other and with a previously available midge-inferred water-level reconstruction from the same core, showing a period of lower water level around AD 300–1000 and suggesting that the methods are valid for paleolimnological and -climatological use.


2013 ◽  
Vol 6 (3-4) ◽  
pp. 1-11 ◽  
Author(s):  
Andrea Kiss ◽  
József Laszlovszky

Abstract In the present paper an overview of published and unpublished results of archaeological and sedimentary investigations, predominantly reflect on 14th-16th-century changes, are provided and evidence compared to documentary information on flood events and long-term changes. Long-term changes in flood behaviour (e.g. frequency, intensity, seasonality) and average water-level conditions had long-term detectable impacts on sedimentation and fluvio-morphological processes. Moreover, the available archaeological evidence might also provide information on the reaction of the society, in the form of changes in settlement organisation, building structures and processes. At present, information is mainly available concerning the 16th, and partly to the 14th-15th centuries. These results were compared to the available documentary evidence on 14th-16th century Danube floods occurred in the Carpathian Basin.


2020 ◽  
Vol 12 (22) ◽  
pp. 3788
Author(s):  
Yakun Han ◽  
Jingui Zou ◽  
Zhong Lu ◽  
Feifei Qu ◽  
Ya Kang ◽  
...  

Wuhan, the largest city in central China, has experienced rapid urban development leading to land subsidence as well as environmental concerns in recent years. Although a few studies have analyzed the land subsidence of Wuhan based on ALOS-1, Envisat, and Sentinel-1 datasets, the research on long-term land subsidence is still lacking. In this study, we employed multi-temporal InSAR to investigate and reveal the spatiotemporal evolution of land subsidence over Wuhan with ALOS-1, Envisat, and Sentinel-1 images from 2007–2010, 2008–2010, 2015–2019, respectively. The results detected by InSAR were cross-validated by two independent SAR datasets, and leveling observations were applied to the calibration of InSAR-derived measurements. The correlation coefficient between the leveling and InSAR has reached 0.89. The study detected six main land subsidence zones during the monitoring period, with the maximum land subsidence velocity of −46 mm/a during the 2015–2019 analysis. Both the magnitude and the extent of the land subsidence have reduced since 2017. The causes of land subsidence are discussed in terms of urban construction, Yangtze river water level changes, and subsurface water level changes. Our results provide insight for understanding the causes of land subsidence in Wuhan and serve as reference for city management for reducing the land subsidence in Wuhan and mitigating the potential hazards.


Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1433
Author(s):  
Hong-Duck Sou ◽  
Masaya Masumori ◽  
Goro Ezaki ◽  
Takeshi Tange

Syzygium kunstleri, a woody plant species, adapts to hypoxic conditions by developing new adventitious roots. Here, we investigate its morphological adaptation to long-term water level changes and the sources and pathways of O2 supplied to its adventitious roots. Cuttings were cultivated in hydroponic and agar media, and then, the water level was increased by 6 cm following adventitious root emergence; afterward, O2 partial pressure changes were measured using a Clark-type O2 microelectrode. O2 concentrations in the adventitious roots decreased when N2 was injected, regardless of the presence of light, indicating that the O2 source was not photosynthetic when bark was removed. New adventitious roots developed near the surface when the water level increased, and O2 conditions above the raised water level influenced O2 concentrations in adventitious roots. O2 concentrations in adventitious roots that developed before the water level increased were lower than in the newly developed adventitious roots but increased when the O2 concentrations above the original water level increased. Our study highlights morphological changes, such as the development of adventitious roots, as environmental adaptation mechanisms. By revealing O2 sources in S. kunstleri under hypoxic environments, we offer insights into the challenges of long-term adaptation to changing environments in woody plants.


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