scholarly journals An Improved Conceptual Model Quantifying the Effect of Climate Change and Anthropogenic Activities on Vegetation Change in Arid Regions

2019 ◽  
Vol 11 (18) ◽  
pp. 2110
Author(s):  
Yu ◽  
Yang ◽  
Li ◽  
Yang
Keyword(s):  
Climate Change ◽  
Conceptual Model ◽  
Arid Regions ◽  
Vegetation Change ◽  
Hydrological Cycle ◽  
Anthropogenic Activities ◽  
Regional Scale ◽  
Anthropogenic Activity ◽  
Area Index ◽  
The Impact

Vegetation shows a greening trend on the global scale in the past decades, which has an important effect on the hydrological cycle, and thus quantitative interpretation of the causes for vegetation change is of great benefit to understanding changes in ecology, climate, and hydrology. Although the Donohue13 model, a simple conceptual model based on gas exchange theory, provides an effective tool to interpret the greening trend, it cannot be used to evaluate the impact from land use and land cover change (LULCC) on the regional scale, whose importance to vegetation change has been demonstrated in a large number of studies. Hence, we have improved the Donohue13 model by taking into account the change in vegetation cover ratio due to LULCC, and applied this model to the Yarkand Oasis in the arid region of northwest China. The estimated change trend in leaf area index (LAI) is 1.20%/year from 2001 to 2017, which accounts for approximately half of the observed (2.31%/year) by the moderate resolution imaging spectroradiometer (MODIS). Regarding the causes for vegetation greening, the contributions of: (1) LULCC; (2) atmospheric CO2 concentration; and (3) vapor pressure deficit were: (1) 88.3%; (2) 40.0%; and (3) −28.3%, respectively, which reveals that the largest contribution was from LULCC, which is probably driven by increased total water availability in whole oasis with a constant transpiration in vegetation area. The improved Donohue13 model, a simple but physics-based model, can partially explain the impact of factors related to climate change and anthropogenic activity on vegetation change in arid regions. It can be further combined with the Budyko hypothesis to establish a framework for quantifying the changes in coupled response of vegetation and hydrological processes to environment changes.

scholarly journals Monitoring the Responses of Deciduous Forest Phenology to 2000–2018 Climatic Anomalies in the Northern Hemisphere

2021 ◽  
Vol 13 (14) ◽  
pp. 2806
Author(s):  
Kevin Bórnez ◽  
Aleixandre Verger ◽  
Adrià Descals ◽  
Josep Peñuelas
Keyword(s):  
Climate Change ◽  
Northern Hemisphere ◽  
Deciduous Forest ◽  
Regional Scale ◽  
The United States ◽  
Deciduous Forests ◽  
Area Index ◽  
Temperature And Precipitation ◽  
Phenological Metrics ◽  
The Impact

Monitoring the phenological responses of deciduous forests to climate is important, due to the increasing frequency and intensity of extreme climatic events associated with climate change and global warming, which will in turn affect vegetation seasonality. We investigated the spatiotemporal patterns of the response of deciduous forests to climatic anomalies in the Northern Hemisphere, using satellite-derived phenological metrics from the Copernicus Global Land Service Leaf Area Index, and multisource climatic datasets for 2000–2018 at resolutions of 0.1°. Thereafter, we assessed the impact of extreme heatwaves and droughts on this deciduous forest phenology. We assumed that changes in the deciduous forest phenology in the Northern Hemisphere for the period 2000–2018 were monotonic, and that temperature and precipitation were the main climatic drivers. Analyses of partial correlations of phenological metrics with the timing of the start of the season (SoS), end of the season (EoS), and climatic variables indicated that changes in preseason temperature played a stronger role than precipitation in affecting the interannual variability of SoS anomalies: the higher the temperature, the earlier the SoS in most deciduous forests in the Northern Hemisphere (mean correlation coefficient of –0.31). Correlations between the SoS and temperature were significantly negative in 57% of the forests, and significantly positive in 15% of the forests (P < 0.05). Both temperature and precipitation contributed to the advance and delay of the EoS. A later EoS was significantly correlated with a positive Standardized Precipitation Evapotranspiration Index (SPEI) at the regional scale (~30% of deciduous forests). The timings of the EoS and SoS shifted by > 20 d in response to heatwaves throughout most of Europe in 2003, and in the United States of America in 2012. This study contributes to improve our understanding of the phenological responses of deciduous forests in the Northern Hemisphere to climate change and extreme climate events.

scholarly journals Assessment of Climate Change Impact on the Hydrology of the Kabul River Basin, Afghanistan

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Massouda Sidiqi ◽  
Sangam Shrestha
Keyword(s):  
Climate Change ◽  
River Basin ◽  
General Circulation ◽  
Arid Regions ◽  
Hydrological Cycle ◽  
Mean Annual Temperature ◽  
The Future ◽  
The Impact ◽  
Semi Arid ◽  
Kabul River

Climate change and variability affect the availability and management of water resources and the hydrological cycle, especially in arid and semi-arid regions. This research was conducted to analyse the impact of climate change on the hydrology of the Kabul River Basin, Afghanistan by using the outputs of three General Circulation Models under two representative concentration pathway scenarios: RCP 4.5 and RCP 8.5. Future climate data (precipitation and temperature) obtained from the climate models were bias-corrected using the delta change approach. Maximum and minimum temperature and precipitation were predicted for the three future periods: 2020s (2010–2039), 2050s (2040–2069), and 2080s (2070–2099) against the baseline period 1961–1980. The o o o mean annual temperature in the basin is projected to increase by 1.8 C, 3.5 C, and 4.8 C in the 2020s, 2050s, and 2080s, respectively. The projected annual precipitation is expected to decline by approximately 53 to 65% for the whole river basin under both scenarios in the future period. The well-calibrated and validated Soil Water Assessment Tool (SWAT) was used to simulate the future streamflow in the basin. The mean annual streamflow is projected to increase by 50 to 120% in the future. This study provides valuable information for guiding future water resource management in the Kabul River Basin and other arid and semi-arid regions of Afghanistan.

scholarly journals Multi-method assessment of reservoir effects on hydrological droughts in an arid region

2016 ◽  
Author(s):  
Sally Rangecroft ◽  
Anne F. Van Loon ◽  
Héctor Maureira ◽  
Koen Verbist ◽  
David M. Hannah
Keyword(s):  
Arid Regions ◽  
Anthropogenic Activities ◽  
Hydrological Regime ◽  
Threshold Level ◽  
Anthropogenic Activity ◽  
Observation Data ◽  
Weap Model ◽  
Level Method ◽  
The Impact ◽  
Hydrological Droughts

Abstract. Increasing pressures on water resources in arid regions have led to their increased management and construction of dams; however, the impacts of these anthropogenic activities on hydrological droughts have yet to be incorporated and assessed. Here, the impact of the Santa Juana dam on hydrological drought characteristics downstream has been analysed in the Huasco basin in northern Chile. Two different methods of drought analysis, threshold level method and standardised indices, were applied to observed and modelled data. An upstream-downstream approach was taken for the observation data, analysing the "disturbed" (post-dam) period and the "undisturbed" (pre-dam) period to allow for an assessment of the onset of the significant anthropogenic activity on the hydrological regime. Modelled data from the Water Evaluation And Planning (WEAP) model generated a naturalised scenario and human-influenced scenario for similar analysis. Our findings show the characteristics of recent drought events in the basin (1965–2013). The reservoir is shown to help alleviate hydrological droughts by reducing frequency, duration and intensity of drought events, though it did not alleviate major multi-year drought events. A delay in timing of drought events has been observed also with the presence of the dam. The reliability of these different methods and approaches to quantify the impact of the dam are evaluated, with concluding recommendations that the threshold level method using an undisturbed threshold may be the most suitable. These findings show an applicable way forward with quantifying the human influence on hydrological droughts, a method that can be applied elsewhere, and on other human activities.

scholarly journals Response of grassland productivity to climate change and anthropogenic activities in arid regions of Central Asia

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9797
Author(s):  
Xu Bi ◽  
Bo Li ◽  
Lixin Zhang ◽  
Bo Nan ◽  
Xinshi Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Central Asia ◽  
Human Activity ◽  
Arid Regions ◽  
Net Primary Production ◽  
Anthropogenic Activities ◽  
Grazing Pressure ◽  
Anthropogenic Activity ◽  
Grassland Degradation ◽  
Basin System

Background Quantitative evaluations of the relative impacts of climate change and anthropogenic activity on grasslands are significant for understanding grassland degradation mechanisms and controlling degraded grasslands. However, our knowledge about the effects of anthropogenic activities and climate change on the grassland in a mountain basin system in arid regions of Central Asia is still subject to great uncertainties. Methods In this research, we have chosen the net primary productivity (NPP) as an index for revealing grassland dynamics processes. Moreover, the human appropriation of net primary production (NPPH), which was calculated as the potential NPP (NPPP) minus the actual NPP (NPPA), was applied to distinguish the relative influences of climate change and human activities on the grassland NPP variations in a mountain basin system of Central Asia from 2001–2015. Results The results indicated that the grassland NPPA showed an increasing trend (35.88%) that was smaller than the decreasing trend (64.12%). The respective contributions of human activity, climate change and the two together to the increase in the NPPA were 6.19%, 81.30% and 12.51%, respectively. Human activity was largely responsible for the decrease in the grassland NPPA, with the area experiencing human-induced decreases accounting for 98.21% of the total decreased area, which mainly occurred during spring/autumn pasture and winter pasture. Furthermore, the average grazing pressure index (GPI) values of summer pastures, spring/autumn pasture and winter pastures were 1.04, 3.03 and 1.83, respectively, from 2001–2015. In addition, negative correlations between the NPP and GPI occupied most of the research area (92.41%). Discussion Our results indicate that: (i) anthropogenic activities were the primary cause of the reduction in the grassland NPP, especially grazing activities. (ii) For areas where the grassland NPP has increased, precipitation was the dominant climatic factor over temperature in controlling the grassland NPP changes in the study area. (iii) The findings of the current research indicate that some measures should be taken to reduce livestock pressure, and artificial grasslands can be built along the Irtysh River and the Ulungur River to relieve grazing pressure on spring/autumn pastures and winter pastures. Our results could provide reliable information for grassland management and the prevention of grassland degradation in arid regions of Central Asia.

scholarly journals Ground-Based MAX-DOAS Observations of Tropospheric NO2 and HCHO During COVID-19 Lockdown and Spring Festival Over Shanghai, China

2021 ◽  
Vol 13 (3) ◽  
pp. 488
Author(s):  
Aimon Tanvir ◽  
Zeeshan Javed ◽  
Zhu Jian ◽  
Sanbao Zhang ◽  
Muhammad Bilal ◽  
...  
Keyword(s):  
Air Quality ◽  
Anthropogenic Activities ◽  
Anthropogenic Activity ◽  
Hysplit Model ◽  
Vertical Column ◽  
Weekly Cycle ◽  
Spring Festival ◽  
Level 1 ◽  
Reduced Mobility ◽  
The Impact

Reduced mobility and less anthropogenic activity under special case circumstances over various parts of the world have pronounced effects on air quality. The objective of this study is to investigate the impact of reduced anthropogenic activity on air quality in the mega city of Shanghai, China. Observations from the highly sophisticated multi-axis differential optical absorption spectroscope (MAX-DOAS) instrument were used for nitrogen dioxide (NO2) and formaldehyde (HCHO) column densities. In situ measurements for NO2, ozone (O3), particulate matter (PM2.5) and the air quality index (AQI) were also used. The concentration of trace gases in the atmosphere reduces significantly during annual Spring Festival holidays, whereby mobility is reduced and anthropogenic activities come to a halt. The COVID-19 lockdown during 2020 resulted in a considerable drop in vertical column densities (VCDs) of HCHO and NO2 during lockdown Level-1, which refers to strict lockdown, i.e., strict measures taken to reduce mobility (43% for NO2; 24% for HCHO), and lockdown Level-2, which refers to relaxed lockdown, i.e., when the mobility restrictions were relaxed somehow (20% for NO2; 22% for HCHO), compared with pre-lockdown days, as measured by the MAX-DOAS instrument. However, for 2019, a reduction in VCDs was found only during Level-1 (24% for NO2; 6.62% for HCHO), when the Spring Festival happened. The weekly cycle for NO2 and HCHO depicts no significant effect of weekends on the lockdown. After the start of the Spring Festival, the VCDs of NO2 and HCHO showed a decline for 2019 as well as 2020. Backward trajectories calculated using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated more air masses coming from the sea after the Spring Festival for 2019 and 2020, implying that a low pollutant load was carried by them. No impact of anthropogenic activity was found on O3 concentration. The results indicate that the ratio of HCHO to NO2 (RFN) fell in the volatile organic compound (VOC)-limited regime.

scholarly journals Assessment of the impact of climate change on the freshwater availability of Kaduna River basin, Nigeria

2018 ◽  
Vol 38 (1) ◽  
pp. 105-114 ◽  
Author(s):  
Gloria C. Okafor ◽  
Kingsley N. Ogbu
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Water Availability ◽  
Hydrological Cycle ◽  
Temporal Trends ◽  
Kendall Test ◽  
Well Being ◽  
Trend Test ◽  
Climate Indices ◽  
The Impact

AbstractChanges in runoff trends have caused severe water shortages and ecological problems in agriculture and human well-being in Nigeria. Understanding the long-term (inter-annual to decadal) variations of water availability in river basins is paramount for water resources management and climate change adaptation. Climate change in Northern Nigeria could lead to change of the hydrological cycle and water availability. Moreover, the linkage between climatic changes and streamflow fluctuations is poorly documented in this area. Therefore, this study examined temporal trends in rainfall, temperature and runoff records of Kaduna River basin. Using appropriate statistical tools and participatory survey, trends in streamflow and their linkages with the climate indices were explored to determine their amplifying impacts on water availability and impacts on livelihoods downstream the basin. Analysis indicate variable rainfall trend with significant wet and dry periods. Unlike rainfall, temperature showed annual and seasonal scale statistically increasing trend. Runoff exhibit increasing tendency but only statistically significant on annual scale as investigated with Mann–Kendall trend test. Sen’s estimator values stood in agreement with Mann–Kendall test for all variables. Kendall tau and partial correlation results revealed the influence of climatic variables on runoff. Based on the survey, some of the hydrological implications and current water stress conditions of these fluctuations for the downstream inhabitants were itemized. With increasing risk of climate change and demand for water, we therefore recommend developing adaptive measures in seasonal regime of water availability and future work on modelling of the diverse hydrological characteristics of the entire basin.

Vulnerability of coastal areas to increased aquifer saturation due to climate change

2021 ◽  
Author(s):  
Alexandre Gauvain ◽  
Ronan Abhervé ◽  
Jean-Raynald de Dreuzy ◽  
Luc Aquilina ◽  
Frédéric Gresselin
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Large Scale ◽  
Regional Scale ◽  
Drainage System ◽  
Hydrological Regime ◽  
Coastal Areas ◽  
Western Coast ◽  
Study Sites ◽  
The Impact

&lt;p&gt;Like in other relatively flat coastal areas, flooding by aquifer overflow is a recurring problem on the western coast of Normandy (France). Threats are expected to be enhanced by the rise of the sea level and to have critical consequences on the future development and management of the territory. The delineation of the increased saturation areas is a required step to assess the impact of climate change locally. Preliminary models showed that vulnerability does not result only from the sea side but also from the continental side through the modifications of the hydrological regime.&lt;/p&gt;&lt;p&gt;We investigate the processes controlling these coastal flooding phenomena by using hydrogeological models calibrated at large scale with an innovative method reproducing the hydrographic network. Reference study sites selected for their proven sensitivity to flooding have been used to validate the methodology and determine the influence of the different geomorphological configurations frequently encountered along the coastal line.&lt;/p&gt;&lt;p&gt;Hydrogeological models show that the rise of the sea level induces an irregular increase in coastal aquifer saturations extending up to several kilometers inland. Back-littoral channels traditionally used as a large-scale drainage system against high tides limits the propagation of aquifer saturation upstream, provided that channels are not dominantly under maritime influence. High seepage fed by increased recharge occurring in climatic extremes may extend the vulnerable areas and further limit the effectiveness of the drainage system. Local configurations are investigated to categorize the influence of the local geological and geomorphological structures and upscale it at the regional scale.&lt;/p&gt;

Impact of climate change on abstraction for hydropower and public water supply in Wales, UK

2021 ◽  
Author(s):  
Richard Dallison ◽  
Sopan Patil
Keyword(s):  
Climate Change ◽  
Water Supply ◽  
Hydrological Cycle ◽  
Mitigation Measures ◽  
Public Water Supply ◽  
Worst Case ◽  
Efficient Operation ◽  
Substantial Impact ◽  
Impact Of Climate Change ◽  
The Impact

&lt;p&gt;The impact of climate change on the hydrological cycle and catchment processes has been extensively studied. In Wales, such changes are projected to have a substantial impact on hydrological regimes. However, the impact on the water abstraction capability of key sectors in the country, such as hydropower (HP) and public water supply (PWS), is not yet fully understood. We use the Soil and Water Assessment Tool (SWAT) to generate future (2021-2054) daily streamflows under a worst-case scenario of greenhouse gas emissions (Representative Concentration Pathway 8.5) at two large catchments in Wales, the Conwy and Tywi. SWAT streamflow output is used to estimate the abstractable water resources, and therefore changes in the average generation characteristics for 25 run-of-river HP schemes across Conwy and Tywi and the total unmet demand for a single large PWS abstraction in the Tywi. This unmet PWS demand is assessed using the Water Evaluation And Planning (WEAP) system under increasing, static, and declining demand scenarios. Mann-Kendall trend analysis is performed to detect and characterise the trends for both sectors.&lt;/p&gt;&lt;p&gt;Results show greater seasonality in abstraction potential through the study period, with an overall decrease in annual abstraction volume due to summer and autumn streamflow declines outweighing increases seen in winter and spring. For HP, these trends result in a projected decline in annual power generation potential, despite an increasing number of days per year that maximum permitted abstraction is reached. For PWS, under all future demand scenarios, annually there is an increase in the number of days where demand is not met as well as the total shortfall volume of water. Our results suggest that currently installed HP schemes may not make optimal use of future flows, and that the planning of future schemes should take account of these to ensure the most efficient operation is achieved. Moreover, PWS supply sustainability is under threat and will require management and mitigation measures to be implemented to ensure future supplies. Overall, our study provides a novel perspective on the future water resource availability in Wales, giving context to management planning to ensure future HP generation efficiency and PWS sustainability.&lt;/p&gt;

scholarly journals Monitoring the Impact of Environmental Manipulation on Peatland Surface by Simple Remote Sensing Indices

2018 ◽  
Vol 23 ◽  
pp. 00030 ◽  
Author(s):  
Anshu Rastogi ◽  
Subhajit Bandopadhyay ◽  
Marcin Stróżecki ◽  
Radosław Juszczak
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Vegetation Index ◽  
Near Infrared ◽  
Near Infrared Reflectance ◽  
Area Index ◽  
Environmental Manipulation ◽  
Chlorophyll Index ◽  
The Impact ◽  
Remote Sensing Indices

The behaviour of nature depends on the different components of climates. Among these, temperature and rainfall are two of the most important components which are known to change plant productivity. Peatlands are among the most valuable ecosystems on the Earth, which is due to its high biodiversity, huge soil carbon storage, and its sensitivity to different environmental factors. With the rapid growth in industrialization, the climate change is becoming a big concern. Therefore, this work is focused on the behaviour of Sphagnum peatland in Poland, subjected to environment manipulation. Here it has been shown how a simple reflectance based technique can be used to assess the impact of climate change on peatland. The experimental setup consists of four plots with two kind of manipulations (control, warming, reduced precipitation, and a combination of warming and reduced precipitation). Reflectance data were measured twice in August 2017 under a clear sky. Vegetation indices (VIs) such as Normalized Difference Vegetation Index (NDVI), Photochemical Reflectance Index (PRI), near-infrared reflectance of vegetation (NIRv), MERIS terrestrial chlorophyll index (MTCI), Green chlorophyll index (CIgreen), Simple Ration (SR), and Water Band Index (WBI) were calculated to trace the impact of environmental manipulation on the plant community. Leaf Area Index of vascular plants was also measured for the purpose to correlate it with different VIs. The observation predicts that the global warming of 1°C may cause a significant change in peatland behaviour which can be tracked and monitored by simple remote sensing indices.

scholarly journals Expected changes in water resources availability and water quality with respect to climate change in the Elbe River basin (Germany)

2005 ◽  
Vol 36 (4-5) ◽  
pp. 321-333 ◽  
Author(s):  
Valentina Krysanova ◽  
Fred Hattermann ◽  
Anja Habeck
Keyword(s):  
Climate Change ◽  
Water Quality ◽  
River Basin ◽  
Hydrological Cycle ◽  
Water Discharge ◽  
Regional Scale ◽  
Elbe River ◽  
Elbe River Basin ◽  
The Mean ◽  
The Elbe River

Reliable modelling of climate–water interactions at the river basin and regional scale requires development of advanced modelling approaches at scales relevant for assessing the potential effects of climate change on the hydrological cycle. These approaches should represent the atmospheric, surface and subsurface hydrological processes and take into account their characteristic temporal and spatial scales of occurrence. The paper presents a climate change impact assessment performed for the Elbe River basin in Germany (about 100 000 km2). The method used for the study combines: (a) a statistical downscaling method driven by GCM-predicted temperature trend for producing climate scenarios, and (b) a simulation technique based on an ecohydrological semi-distributed river basin model, which was thoroughly validated in advance. The overall result of the climate impact study for the basin is that the mean water discharge and the mean groundwater recharge in the Elbe basin will be most likely decreased under the expected climate change and diffuse source pollution will be diminished. Our study confirms that the uncertainty in hydrological and water quality responses to changing climate is generally higher than the uncertainty in climate input. The method is transferable to other basins in the temperate zone.

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