scholarly journals Changes in Lake Area in Response to Climatic Forcing in the Endorheic Hongjian Lake Basin, China

2019 ◽  
Vol 11 (24) ◽  
pp. 3046
Author(s):  
Kang Liang ◽  
Yanzhong Li
Keyword(s):  
Climate Change ◽  
Correlation Analysis ◽  
Correlation Coefficient ◽  
Water Resource Management ◽  
Climatic Factors ◽  
Lake Basin ◽  
Type I ◽  
Lake Area ◽  
Climatic Forcing ◽  
Lag Period

Endorheic lakes are key components of the water cycle and the ecological system in endorheic basins. The endorheic Hongjian Lake wetland is China’s national nature reserve for protecting the vulnerable species of Relict Gull. The Hongjian Lake, once China’s largest desert freshwater lake, has been suffering from severe shrinkage in the last two decades, yet the variations in the lake area and its responses to climate change are poorly understood due to a lack of in situ observations. In this study, using Landsat remote sensing images, the Modified Normalized Difference Water Index, and nonparametric tests, we obtained the Hongjian Lake area changes on the annual, seasonal, and quasi-monthly scales during 1988–2014, analyzed the corresponding variations of the six climatic factors in the Hongjian Lake Basin (HJLB) using satellite-based products, and investigated the multi-scale response characteristics of lake area to climatic forcing using correlation analysis. The results showed that the lake area decreased during 1988–2014, and this process can be divided into two sub-stages, namely the first slight increasing sub-phase in 1988–1999 and the second significant declining sub-phase in 2000–2014. The shifts in patterns of the seasonal cycle had three types: as the natural rhythm of the lake changes has been broken by intensive human activities since the late 1990s, the natural bimodal type I has obviously changed into non-natural bimodal type II and unimodal type III, featured by a declining peak in July–September. The climatic wet/dry regime on multi-scales during 1988–2014 in the HJLB was generally warming and drying, mainly reflected by the increase in temperature (T), arid index (AI) and evaporation (ET0, ETa), and the decrease in the precipitation (Pre) and actual water difference (AWD). There were large differences in the climatic factors at different time scales, especially in the wet and dry seasons. When the lagged effect, the cumulative effect, and the lagged and cumulative combined effect were gradually considered, the correlation coefficient significantly increased, and the direction of the correlation coefficient became coincident with common sense. The correlation analysis identified a lag period of approximately 1–3 years on an annual scale, and a lag period of approximately 1–3 months on a monthly scale. This study could provide a certain scientific reference for climate change detection, water resource management, and species habitat protection in the HJLB and similar endorheic basins or inland arid regions.

scholarly journals Contrasting Evolution Patterns of Endorheic and Exorheic Lakes on the Central Tibetan Plateau and Climate Cause Analysis during 1988–2017

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1962
Author(s):  
Zhilong Zhao ◽  
Yue Zhang ◽  
Zengzeng Hu ◽  
Xuanhua Nie
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Climatic Factors ◽  
Global Climate ◽  
Rapid Expansion ◽  
Annual Precipitation ◽  
The Tibetan Plateau ◽  
Lake Area ◽  
Climate Change Research ◽  
Mean Temperature

The alpine lakes on the Tibetan Plateau (TP) are indicators of climate change. The assessment of lake dynamics on the TP is an important component of global climate change research. With a focus on lakes in the 33° N zone of the central TP, this study investigates the temporal evolution patterns of the lake areas of different types of lakes, i.e., non-glacier-fed endorheic lakes and non-glacier-fed exorheic lakes, during 1988–2017, and examines their relationship with changes in climatic factors. From 1988 to 2017, two endorheic lakes (Lake Yagenco and Lake Zhamcomaqiong) in the study area expanded significantly, i.e., by more than 50%. Over the same period, two exorheic lakes within the study area also exhibited spatio-temporal variability: Lake Gaeencuonama increased by 5.48%, and the change in Lake Zhamuco was not significant. The 2000s was a period of rapid expansion of both the closed lakes (endorheic lakes) and open lakes (exorheic lakes) in the study area. However, the endorheic lakes maintained the increase in lake area after the period of rapid expansion, while the exorheic lakes decreased after significant expansion. During 1988–2017, the annual mean temperature significantly increased at a rate of 0.04 °C/a, while the annual precipitation slightly increased at a rate of 2.23 mm/a. Furthermore, the annual precipitation significantly increased at a rate of 14.28 mm/a during 1995–2008. The results of this study demonstrate that the change in precipitation was responsible for the observed changes in the lake areas of the two exorheic lakes within the study area, while the changes in the lake areas of the two endorheic lakes were more sensitive to the annual mean temperature between 1988 and 2017. Given the importance of lakes to the TP, these are not trivial issues, and we now need accelerated research based on long-term and continuous remote sensing data.

scholarly journals Effects of Climate and Land Use/Land Cover Changes on Water Yield Services in the Dongjiang Lake Basin

2021 ◽  
Vol 10 (7) ◽  
pp. 466
Author(s):  
Wenbo Mo ◽  
Yunlin Zhao ◽  
Nan Yang ◽  
Zhenggang Xu ◽  
Weiping Zhao ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Water Resource Management ◽  
Water Source ◽  
Water Yield ◽  
Lake Basin ◽  
Lake Area ◽  
Land Use Land Cover ◽  
Lulc Changes ◽  
Regional Water

Spatial and quantitative assessments of water yield services in watershed ecosystems are necessary for water resource management and improved water ecological protection. In this study, we used the InVEST model to estimate regional water yield in the Dongjiang Lake Basin in China. Moreover, we designed six scenarios to explore the impacts of climate and land use/land cover (LULC) changes on regional water yield and quantitatively determined the dominant mechanisms of water yield services. The results are expected to provide an important theoretical reference for future spatial planning and improvements of ecological service functions at the water source site. We found that (1) under the time series analysis, the water yield changes of the Dongjiang Lake Basin showed an initial decrease followed by an increase. Spatially, water yield also decreased from the lake area to the surrounding region. (2) Climate change exerted a more significant impact on water yield changes, contributing more than 98.26% to the water yield variability in the basin. In contrast, LULC had a much smaller influence, contributing only 1.74 %. (3) The spatial distribution pattern of water yield services in the watershed was more vulnerable to LULC changes. In particular, the expansion of built-up land is expected to increase the depth of regional water yield and alter its distribution, but it also increases the risk of waterlogging. Therefore, future development in the basin must consider the protection of ecological spaces and maintain the stability of the regional water yield function.

CLINICAL, ECHOGRAPHIC, MORPHOLOGICAL AND IMMUNOLOGICAL CRITERIA FOR EVALUATING A WELL-FOUNDED SCAR ON THE UTERUS AFTER CESAREAN SECTION

2021 ◽  
Vol Special issue (1) ◽  
pp. 57-61
Author(s):  
Venera Kurbaniyazova ◽  
Keyword(s):  
Correlation Analysis ◽  
Cesarean Section ◽  
Correlation Coefficient ◽  
Significant Relationship ◽  
Strong Correlation ◽  
Type I Collagen ◽  
Morphological Features ◽  
Average Degree ◽  
Type I ◽  
Uterine Scar

The results of the conducted studies 102 of the manufacturer testify to the presence of essential clinical and echographic, immunological and morphological features of the "wealthy" or "insolvent" scar on the uterus after the cesarean section. The correlation analysis with the calculation of the Correlation coefficient of Gamma (G) indicates a statistically significant relationship between the average degree between the way of the delivery and the scar thickness (G = 0.55, p = 0.001), strong correlation between the ultrasound data (G = 0.74 , p = 0.002) and antibodies to type I collagen (G = 0.93, p = 0.003). Determining the level of antibodies to the type I collagen is the mostimportant criterion confirming the usefulness of the scar on the uterus.Keywords: cesarean section, uterine scar, pregnancy

The Coincident Relationships between the Qehan Lake Area Fluctuation and the Climate Change in the Nearly 40 Years

2011 ◽  
Vol 137 ◽  
pp. 286-290 ◽  
Author(s):  
Xi Chun ◽  
Mei Jie Zhang ◽  
Mei Ping Liu
Keyword(s):  
Climate Change ◽  
Inner Mongolia ◽  
Climatic Factors ◽  
Annual Precipitation ◽  
Lake Area ◽  
Annual Average ◽  
Average Temperature ◽  
Changing Patterns ◽  
Annual Evaporation ◽  
Annual Average Temperature

The objective of this study is to analyse the climate changing patterns chronologically for exposing the coincident relationships between the lake area fluctuation and the climate change in Qehan lake of Abaga county of Inner Mongolia. The results show that there’s highly interrelation between the changes of the lake area and the climatic factors here, the annual average temperature and annual evaporation are negatively interrelate to the lake area fluctuation, and the annual precipitation interrelate to it is positive. The lake area has descended about 75 km2 during the nearly past 40 years. There were about two considerable lake expansions in 1973, 1998 through the generally lake area descending process.

scholarly journals Relationships between Temporal and Spatial Changes in Lakes and Climate Change in the Saline-Alkali Concentrated Distribution Area in the Southwest of Songnen Plain, Northeast China, from 1985 to 2015

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3557
Author(s):  
Zhaoyang Li ◽  
Yidan Cao ◽  
Jie Tang ◽  
Yao Wang ◽  
Yucong Duan ◽  
...  
Keyword(s):  
Climate Change ◽  
Northeast China ◽  
Climatic Factors ◽  
Test Method ◽  
Annual Precipitation ◽  
Distribution Area ◽  
Lake Area ◽  
Songnen Plain ◽  
Contribution Rate ◽  
Large Lakes

The southwest of Songnen Plain, Northeast China, has an arid climate and is a typical concentrated distribution area of saline-alkali soil. The terrain here is low-lying, with many small, shallow lakes that are vulnerable to climate change. This paper used Landsat satellite remote sensing images of this area from 1985 to 2015 to perform interpretation of lake water bodies, to classify the lakes according to their areas, and to analyze the spatial dynamic characteristics of lakes in different areas. During the 30 years from 1985 to 2015, the number of lakes in the study area decreased by 71, and the total lake area decreased by 266.85 km2. The decrease was more serious in the east and northeast, and the appearance and disappearance of lakes was drastic. The Mann–Kendall test method was used to analyze trends in meteorological factors (annual mean temperature, annual precipitation, and annual evaporation) in the study area and perform mutation tests. Through correlation analysis and multiple generalized linear model analysis, the response relationship between lake change and climate change was quantified. The results showed that the average temperature in the area is rising, and the annual precipitation and evaporation are declining. Temperature and precipitation mainly affected lakes of less than 1 km2, with a contribution rate of 31.2% and 39.4%, and evaporation had a certain correlation to the total lake area in the study area, with a contribution rate of 60.2%. Small lakes are susceptible to climatic factors, while large lakes, which are mostly used as water sources, may be influenced more by human factors. This is the problem and challenge to be uncovered in this article. This research will help to improve our understanding of lake evolution and climate change response in saline-alkali areas and provide scientific basis for research into lakes’ (reservoirs’) sustainable development and protection.

Historical environmental changes in the Poyang Lake basin (Yangtze River, China) and impacts on agricultural activities

The Holocene ◽  
2021 ◽  
pp. 095968362110477
Author(s):  
Maofeng He ◽  
Fengxian Bu ◽  
Claudio O Delang ◽  
Jialin Xie ◽  
Quan Ye ◽  
...  
Keyword(s):  
Climate Change ◽  
Lake Water ◽  
Human Activities ◽  
Environmental Changes ◽  
Poyang Lake ◽  
Lake Basin ◽  
Lake Area ◽  
Poyang Lake Basin ◽  
Past 2000 Years ◽  
Floods And Droughts

Climate change and human activities have been an important part of studies regarding historical environmental changes in China over the past 2000 years. In this study, we focused on environmental changes, that is, natural disasters and human activities, in the Poyang Lake Basin over the past 2000 years, to analyze interactions between land use cover changes and human activities from the perspective of regional sustainable development. We collected historical records of climate and hydrology, floods and droughts, and rivers and lakes in the Poyang Lake area, and established time sequences for the floods and droughts, lake water level and lake area, amount of farming land, and population, in order to discuss interactions between changes in the environment and the climate, with emphasis on the impacts of extreme events on lake and river basin environment changes. The following results were obtained. First, climate changes in historical periods had wide-ranging and far-reaching impacts on agricultural production, especially disasters caused by climate change. Among the changes in the Poyang Lake basin environment, including river network systems, lake water levels, etc., changes in lake water volume are direct evidence of climate change, adaptation to climate change, and obvious phased characteristics. Second, in the process of changes to the lake and river network in the Poyang Lake Basin, social and economic development is accompanied by evolution of the lake. Increases and decreases in population, the scale of agricultural production, and lake environment changes have direct and significant interactions. Third, the Poyang Lake basin’s environmental changes during the historical period are mainly reflected in the pressure feedback mode of “population–agriculture” in the lake environment.

scholarly journals The Response of Net Primary Production to Climate Change: A Case Study in the 400 mm Annual Precipitation Fluctuation Zone in China

2019 ◽  
Vol 16 (9) ◽  
pp. 1497 ◽  
Author(s):  
Yang Li ◽  
Yaochen Qin
Keyword(s):  
Climate Change ◽  
Correlation Analysis ◽  
Primary Production ◽  
Correlation Coefficient ◽  
Land Surface ◽  
Partial Correlation ◽  
Net Primary Production ◽  
Annual Precipitation ◽  
The Future ◽  
Total Study Area

The regions in China that intersect the 400 mm annual precipitation line are especially ecologically sensitive and extremely vulnerable to anthropogenic activities. However, in the context of climate change, the response of vegetation Net Primary Production (NPP) in this region has not been scientifically studied in depth. NPP suffers from the comprehensive effect of multiple climatic factors, and how to eliminate the effect of interfering variables in the correlation analysis of NPP and target variables (temperature or precipitation) is the major challenge in the study of NPP influencing factors. The correlation coefficient between NPP and target variable was calculated by ignoring other variables that also had a large impact on NPP. This increased the uncertainty of research results. Therefore, in this study, the second-order partial correlation analysis method was used to analyze the correlation between NPP and target variables by controlling other variables. This can effectively decrease the uncertainty of analysis results. In this paper, the univariate linear regression, coefficient of variation, and Hurst index estimation were used to study the spatial and temporal variations in NPP and analyze whether the NPP seasonal and annual variability will persist into the future. The results show the following: (i) The spatial distribution of NPP correlated with precipitation and had a gradually decreasing trend from southeast to northwest. From 2000 to 2015, the NPP in the study area had a general upward trend, with a small variation in its range. (ii) Areas with negative partial correlation coefficients between NPP and precipitation are consistent with the areas with more abundant water resources. The partial correlation coefficient between the NPP and the Land Surface Temperature (LST) was positive for 52.64% of the total study area. Finally, the prediction of the persistence of NPP variation into the future showed significant differences on varying time scales. On an annual scale, NPP was predicted to persist for 46% of the study area. On a seasonal scale, NPP in autumn was predicted to account for 49.92%, followed by spring (25.67%), summer (13.40%), and winter (6.75%).

scholarly journals ADAPTATION STRATEGIES OF FOOD SECURITY FOR CLIMATE CHANGE

2015 ◽  
Vol 4 (3) ◽  
pp. 11-19
Author(s):  
Sajani Shrestha
Keyword(s):  
Climate Change ◽  
Food Security ◽  
Adaptation Strategies ◽  
Lake Basin ◽  
Lake Area ◽  
Business Service ◽  
Chemical Fertilizers ◽  
Small Shop ◽  
Structured Questionnaire ◽  
Impacts Of Climate Change

 The Rupa lake area in Lekhnath Municipality of Kaski district, at Rupa Lake basin areas of Nepal was selected to explore the impacts of climate change on livelihoods in term of food security. 20% of the wetland dependent communities constituted of sample household (HHs). Semi-structured questionnaire was taken for focused group consultations. It was found that majority of population (87%) of lake basin is dependent on agriculture for food security. There is a year-round food security for 50% of sample HHs, with 22% of this having surplus food. About 5% of HHs has food security for less than three months where as 19% HHs have food security for more than six months. Within this scenario, over 90% HHs responded to climate change in the form of rise in temperature (74%); unpredictable rainfall (77%); shift in rainfall (64%); and phonological changes (51%). About 74% of households are aware about the effect of climate change and had adopted different strategies to resist against the effect of climate change. Out of the 74% of HHs, more than 50% of the household use chemical fertilizers and agricultural inputs and other means to cope small shop (business), service, labor and remittance against the climate change.International Journal of Environment Volume-4, Issue-3, June-August 2015Page: 11-19

Analysis of the role of climatic and human factors in runoff variations (case study: Lighvan River in Urmia Lake Basin, Iran)

2019 ◽  
Vol 11 (1) ◽  
pp. 291-302 ◽  
Author(s):  
R. Kanani ◽  
A. Fakheri Fard ◽  
M. A. Ghorbani ◽  
Y. Dinpashoh
Keyword(s):  
Climate Change ◽  
Human Factors ◽  
Human Activities ◽  
Climatic Factors ◽  
Hydrologic Model ◽  
Climatic Variables ◽  
Data Series ◽  
Lake Basin ◽  
Discharge Data ◽  
The Impact

Abstract In recent years, river flows have significantly decreased due to regional or global climate change and human activities, especially in the arid and semi-arid regions. In this study, the effects of climate change and human activities on the runoff responses were examined using hydrologic sensitivity analysis and hydrologic model simulation in the Lighvan basin located in the northwest of Iran. The Mann–Kendall test was applied to identify the trends in hydroclimatic data series. Also, the Pettitt test was used to detect change points in the annual discharge values and climatic variables. The results showed that there was negative trend in discharge data series, and examination of the climatic factors indicated that there was an increase in the temperature values and a decrease in the relative humidity values at the basin. The rapid changes in runoff values and most of the climatic variables occurred in the mid-1990s. The effect percentages of the human factors and climatic factors on runoff reduction in all the models used were 65–84% and 16–35%, respectively. Therefore, the impact of human activities on the river flow changes was significant.

scholarly journals Sample Size Guideline for Correlation Analysis

2016 ◽  
Vol 3 (1) ◽  
pp. 37 ◽  
Author(s):  
Mohamad Adam Bujang ◽  
Nurakmal Baharum
Keyword(s):  
Correlation Analysis ◽  
Sample Size ◽  
Correlation Coefficient ◽  
Type I Error ◽  
Sample Size Calculation ◽  
P Value ◽  
Type I ◽  
Size Estimation ◽  
Study Objective ◽  
Type 1 Error

<p class="Abstract"><em>Correlation analysis is a common statistical analysis in various fields. The aim is usually to determine to what extent two numerical variables are correlate</em><em>d</em><em> with each other. One of the issues that are important to be considered before conducting any correlation analysis is to plan for the sufficient sample size. This is to ensure, the results that to be derived from the analysis be able to reach a desired minimum correlation coefficient value with sufficient power and desired type I error or p-value. Sample size estimation for correlation analysis should be in line with the study objective. Researchers who are not statistician need simpler guideline to determine the sufficient sample size for correlation analysis. Therefore, this study aims to tabulate tables that show sample size calculation based on desired correlation coefficient, power and type 1 error (p-value) values. Moving towards that, simpler guidelines are proposed to estimate sufficient sample size requirements in different scenarios.</em></p>

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