scholarly journals A Subregional Model of System Dynamics Research on Surface Water Resource Assessment for Paddy Rice Production under Climate Change in the Vietnamese Mekong Delta

Climate ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 41
Author(s):  
Tuu Nguyen Thanh ◽  
Van Pham Dang Tri ◽  
Seungdo Kim ◽  
Thuy Nguyen Phuong ◽  
Thuy Lam Mong ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
System Dynamics ◽  
Sea Level ◽  
Water Consumption ◽  
Human Activities ◽  
Environmental Changes ◽  
Mekong Delta ◽  
Coastal Areas ◽  
Dry Season

Effective water management plays an important role in socioeconomic development in the Vietnamese Mekong Delta (VMD). The impacts of climate change and human activities (that is, domestic consumption and industrial and agricultural activities) vary in different subregions of the delta. In order to provide intersectoral data for determining the significantly impacted subregions of the VMD, the present study simulated interactions between local climatic patterns, human activities, and water resources using a system dynamics modeling (SDM) approach with each subregion as an agent of the developed model. The average rainfall and temperature of 121 subregions in the VMD were collected during 1982–2012, and the future changes of climate by provinces were based on the Representative Concentration Pathways (RCP) scenarios (RCP4.5 and RCP8.5) by the end of 21st century. The assessment was based on the levels of impact of various factors, including (1) water consumption, (2) differences between evapotranspiration and rainfall, and (3) spatial distribution of salinity intrusion over the delta scale. In the coastal areas, as well as the central and upstream areas, water resources were projected to be affected by environmental changes, whereas the former, characterized by the lack of surface freshwater, would be affected at a greater scale during the dry season. Besides, the sea level rise would lead to an increase in negative impacts in the eastern coastal areas, suggesting that water-saving techniques should be applied not only for agriculture, but also for industry and domestic water consumption during the dry season. In addition, the south subregions (that is, the western subregions of the Hau River except for An Giang) were likely to be flooded due to the simulated high rainfall and seasonal rises of sea level during the wet season. Therefore, the alternative forms of settlement and livelihood should be considered toward balance management with changing delta dynamics.

scholarly journals Global warming and climate change with reference to South Africa. Some perspectives

2008 ◽  
Vol 27 (4) ◽  
pp. 294-306 ◽  
Author(s):  
Gawie De Villiers ◽  
Giel Viljoen ◽  
Herman Booysen
Keyword(s):  
Climate Change ◽  
South Africa ◽  
Global Warming ◽  
Human Activities ◽  
Industrial Revolution ◽  
Environmental Changes ◽  
Storm Surges ◽  
Flood Damage ◽  
Coastal Areas ◽  
Sufficient Evidence

According to the geological history of the earth, climate change is an integral part of environmental changes that occurred over time. Sufficient evidence is provided of recurrent wet and dry and cold and hot periods due to natural circumstances. Since the industrial revolution human activities increasingly contribute to air pollution by releasing huge volumes of carbon dioxide and other gasses into the atmosphere, so much so that it is generally accepted that increase in global warming the past decades is directly linked to human activities. Observable signs of human induced climate change include increasing average temperatures at many places, melting ice caps in polar areas, rising sea levels on a global scale and coastal disturbances and damages due to storm surges on coastal areas in various countries, also in South Africa. Consensus from a number of hydrological-meteorological circulation models show, for South Africa, a rise in average annual winter and summer temperatures of between 1.5 and 3.0 degrees Centigrade the following number of decades with a strong possibility of an increase in rainfall in the eastern parts and a decrease in rainfall in the western parts. Bigger floods and longer droughts should occur more frequently as well as severe sea onslaught activities along the eastern and south-eastern coastal areas. The net impact of the predictions on the community is negative. There is though other scientists who indicate that no concrete proof of climate change in South Africa exists; including changes with regard to river floods and droughts. According to more beneficial than detrimental. Despite the differences in opinion about the relative contribution of natural and human activities to the present global warming, changes in hydrological and characteristics of floods in several parts of South Africa in the immediate past, necessitate modifications to available models and approaches to flood damage management and control. Flood conditions need to be managed with applicable models. Modifications are furthermore essential as a result of meaningful demographic, social, physical and economic changes in the working and living environments of people and communities.

scholarly journals Future upstream water consumption and its impact on downstream availability in the transboundary Indus basin

2021 ◽  
Author(s):  
Wouter J. Smolenaars ◽  
Sanita Dhaubanjar ◽  
Muhammad K. Jamil ◽  
Arthur Lutz ◽  
Walter Immerzeel ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Water Consumption ◽  
Water Availability ◽  
Dry Season ◽  
Indus Basin ◽  
Future Climate Change ◽  
Relative Pressure ◽  
Steep Decline ◽  
The Impact

Abstract. The densely populated plains of the lower Indus basin largely depend on water resources originating in the mountains of the upper Indus basin. Although recent studies have improved our understanding of this upstream-downstream linkage and the impact of climate change, water use in the mountainous part of the Indus has been largely ignored. This study quantifies the comparative impact of upper Indus water usage on downstream water availability under future climate change and socio-economic development. Future water consumption and relative pressure on water resources vary greatly between upper Indus sub-basins and seasons. During the dry season, the share of surface water required within the upper Indus is high and increasing, and in some sub-basins future water requirements exceed availability during the critical winter months. In the lower Indus this causes spatiotemporal hotspots to emerge where seasonal water availability is reduced by over 25 % compared to natural conditions. This plays an important, but previously not accounted for, compounding role in the steep decline of per capita seasonal water availability in the lower Indus in the future due to downstream population growth. Increasing consumption in the upper Indus may thus locally lead to water scarcity issues, and increasingly be a driver of downstream water stress during the dry season. The quantified perspective on the evolving upstream-downstream linkages of the transboundary Indus basin, provided in this study, highlights that long-term water management here must account for rapid socio-economic change in the upper Indus and anticipate increasing upstream-downstream water competition between riparian states.

scholarly journals The Issue of Groundwater Salinization in Coastal Areas of the Mediterranean Region: A Review

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Micòl Mastrocicco ◽  
Nicolò Colombani
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Environmental Changes ◽  
Numerical Models ◽  
Mediterranean Area ◽  
Coastal Areas ◽  
Gis Mapping ◽  
Aquifer Management ◽  
Recent Climate ◽  
The Mediterranean

The Mediterranean area is undergoing intensive demographic, social, cultural, economic, and environmental changes. This generates multiple environmental pressures such as increased demand for water resources, generation of pollution related to wastewater discharge, and land consumption. In the Mediterranean area, recent climate change studies forecast large impacts on the hydrologic cycle. Thus, in the next years, surface and ground-water resources will be gradually more stressed, especially in coastal areas. In this review paper, the historical and geographical distribution of peer-review studies and the main mechanisms that promote aquifer salinization in the Mediterranean area are critically discussed, providing the state of the art on topics such as actual saltwater wedge characterization, paleo-salinities in coastal areas, water-rock interactions, geophysical techniques aimed at delineating the areal and vertical extent of saltwater intrusion, management of groundwater overexploitation using numerical models and GIS mapping techniques for aquifer vulnerability to salinization. Each of the above-mentioned approaches has potential advantages and drawbacks; thus, the best tactic to tackle coastal aquifer management is to employ a combination of approaches. Finally, the number of studies focusing on predictions of climate change effects on coastal aquifers are growing but are still very limited and surely need further research.

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

<p>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.</p><p>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.</p><p>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.</p>

Fluvial sediment fluxes response to modern climate change and human activities in the Tibetan Plateau and its margins

2021 ◽  
Author(s):  
Dongfeng Li ◽  
Xixi Lu ◽  
Ting Zhang
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Human Activities ◽  
Sediment Flux ◽  
The Tibetan Plateau ◽  
Fluvial Sediment ◽  
Sediment Fluxes ◽  
Cold Environments

<p>Sediment flux in cold environments is a crucial proxy to link glacial, periglacial, and fluvial systems and highly relevant to hydropower operation, water quality, and the riverine carbon cycle. However, the long-term impacts of climate change and multiple human activities on sediment flux changes in cold environments remain insufficiently investigated due to the lack of monitoring and the complexity of the sediment cascade. Here we examine the multi-decadal changes in the in-situ observed fluvial sediment fluxes from two types of basins, namely, pristine basins and disturbed basins, in the Tibetan Plateau and its margins. The results show that the fluvial sediment fluxes in the pristine Tuotuohe headwater have substantially increased over the past three decades (i.e., a net increase of 135% from 1985–1997 to 1998–2017) due to the warming and wetting climate. We also quantify the relative impacts of air temperature and precipitation on the increases in the sediment fluxes with a novel attribution approach and finds that climate warming and intensified glacier-snow-permafrost melting is the primary cause of the increased sediment fluxes in the pristine cold environment (Tuotuohe headwater), with precipitation increase and its associated pluvial processes being the secondary driver. By contrast, the sediment fluxes in the downstream disturbed Jinsha River (southeastern margin of the Tibetan Plateau) exhibit a net increase of 42% from 1966-1984 to 1985-2010 mainly due to human activities such as deforestation and mineral extraction (contribution of 82%) and secondly because of climate change (contribution of 18%). Then the sediment fluxes dropped by 76% during the period of 2011-2015 because of the operations of six cascade reservoirs since 2010. In an expected warming and wetting climate for the region, we predict that the sediment fluxes in the pristine headwaters of the Tibetan Plateau will continue to increase throughout the 21st century, but the rising sediment fluxes from the Tibetan Plateau would be mostly trapped in its marginal reservoirs.</p><p>Overall, this work has provided the sedimentary evidence of modern climate change through robust observational sediment flux data over multiple decades. It demonstrates that sediment fluxes in pristine cold environments are more sensitive to air temperature and thermal-driven geomorphic processes than to precipitation and pluvial-driven processes. It also provides a guide to assess the relative impacts of human activities and climate change on fluvial sediment flux changes and has significant implications for water resources stakeholders to better design and manage the hydropower dams in a changing climate. Such findings may also have implications for other cold environments such as the Arctic, Antarctic, and other high mountainous basins.</p><p>Furthermore, this research is under the project of "Water and Sediment Fluxes Response to Climate Change in the Headwater Rivers of Asian Highlands" (supported by the IPCC and the Cuomo Foundation) and the project of "Sediment Load Responses to Climate Change in High Mountain Asia" (supported by the Ministry of Education of Singapore). Part of the results are also published in Li et al., 2018 Geomorphology, Li et al., 2020 Geophysical Research Letters, and Li et al., 2021 Water Resources Research.</p>

scholarly journals Greening Implication Inferred from Vegetation Dynamics Interacted with Climate Change and Human Activities over the Southeast Qinghai–Tibet Plateau

2019 ◽  
Vol 11 (20) ◽  
pp. 2421 ◽  
Author(s):  
Li ◽  
Liu ◽  
Liu ◽  
Li ◽  
Xu
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Environmental Changes ◽  
Growing Season ◽  
Tibet Plateau ◽  
Ecological Environment ◽  
Upstream Region ◽  
High Mountain

Vegetation dynamics are sensitive to climate change and human activities, as vegetation interacts with the hydrosphere, atmosphere, and biosphere. The Yarlung Zangbo River (YZR) basin, with the vulnerable ecological environment, has experienced a series of natural disasters since the new millennium. Therefore, in this study, the vegetation dynamic variations and their associated responses to environmental changes in the YZR basin were investigated based on Normalized Difference Vegetation Index (NDVI) and Global Land Data Assimilation System (GLDAS) data from 2000 to 2016. Results showed that (1) the YZR basin showed an obvious vegetation greening process with a significant increase of the growing season NDVI (Zc = 2.31, p < 0.05), which was mainly attributed to the wide greening tendency of the downstream region that accounted for over 50% area of the YZR basin. (2) Regions with significant greening accounted for 25.4% of the basin and were mainly concentrated in the Nyang River and Parlung Tsangpo River sub-basins. On the contrary, the browning regions accounted for <25% of the basin and were mostly distributed in the urbanized cities of the midstream, implying a significant influence of human activities on vegetation greening. (3) The elevation dependency of the vegetation in the YZR basin was significant, showing that the vegetation of the low-altitude regions was better than that of the high-altitude regions. The greening rate exhibited a significantly more complicated relationship with the elevation, which increased with elevated altitude (above 3500 m) and decreased with elevated altitude (below 3500 m). (4) Significantly positive correlations between the growing season NDVI and surface air temperature were detected, which were mainly distributed in the snow-dominated sub-basins, indicating that glaciers and snow melting processes induced by global warming play an important role in vegetation growth. Although basin-wide non-significant negative correlations were found between precipitation and growing season NDVI, positive influences of precipitation on vegetation greening occurred in the arid and semi-arid upstream region. These findings could provide important information for ecological environment protection in the YZR basin and other high mountain regions.

scholarly journals Threshold effects of hazard mitigation in coastal human–environmental systems

2014 ◽  
Vol 2 (1) ◽  
pp. 35-45 ◽  
Author(s):  
E. D. Lazarus
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Social Dynamics ◽  
Environmental Changes ◽  
Hazard Mitigation ◽  
Nonlinear Effects ◽  
Time Frame ◽  
Global Scale ◽  
Coupling Mechanism ◽  
Environmental Systems

Abstract. Despite improved scientific insight into physical and social dynamics related to natural disasters, the financial cost of extreme events continues to rise. This paradox is particularly evident along developed coastlines, where future hazards are projected to intensify with consequences of climate change, and where the presence of valuable infrastructure exacerbates risk. By design, coastal hazard mitigation buffers human activities against the variability of natural phenomena such as storms. But hazard mitigation also sets up feedbacks between human and natural dynamics. This paper explores developed coastlines as exemplary coupled human–environmental systems in which hazard mitigation is the key coupling mechanism. Results from a simplified numerical model of an agent-managed seawall illustrate the nonlinear effects that economic and physical thresholds can impart into coastal human–environmental system dynamics. The scale of mitigation action affects the time frame over which human activities and natural hazards interact. By accelerating environmental changes observable in some settings over human timescales of years to decades, climate change may temporarily strengthen the coupling between human and environmental dynamics. However, climate change could ultimately result in weaker coupling at those human timescales as mitigation actions increasingly engage global-scale systems.

Coastal flooding in the Balearic Islands during the 21st century caused by sea level rise and extreme events

2020 ◽  
Author(s):  
Pau Luque Lozano ◽  
Lluís Gómez-Pujol ◽  
Marta Marcos ◽  
Alejandro Orfila
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Extreme Events ◽  
Storm Surges ◽  
Coastal Flooding ◽  
Coastal Areas ◽  
Balearic Islands ◽  
Mean Sea Level

&lt;p&gt;Sea-level rise induces a permanent loss of land with widespread ecological and economic impacts, most evident in urban and densely populated areas. The eventual coastline retreat combined with the action of waves and storm surges will end in more severe damages over coastal areas. These effects are expected to be particularly significant over islands, where coastal zones represent a relatively larger area vulnerable to marine hazards.&lt;/p&gt;&lt;p&gt;Managing coastal flood risk at regional scales requires a prioritization of resources and socioeconomic activities along the coast. Stakeholders, such as regional authorities, coastal managers and private companies, need tools that help to address the evaluation of coastal risks and criteria to support decision-makers to clarify priorities and critical sites. For this reason, the regional Government of the Balearic Islands (Spain) in association with the Spanish Ministry of Agriculture, Fisheries and Environment has launched the Plan for Climate Change Coastal Adaptation. This framework integrates two levels of analysis. The first one relates with the identification of critical areas affected by coastal flooding and erosion under mean sea-level rise scenarios and the quantification of the extent of flooding, including marine extreme events. The second level assesses the impacts on infrastructures and assets from a socioeconomic perspective due to these hazards.&lt;/p&gt;&lt;p&gt;In this context, this paper quantifies the effects of sea-level rise and marine extreme events caused by storm surges and waves along the coasts of the Balearic Islands (Western Mediterranean Sea) in terms of coastal flooding and potential erosion. Given the regional scale (~1500 km) of this study, the presented methodology adopts a compromise between accuracy, physical representativity and computational costs. We map the projected flooded coastal areas under two mean sea-level rise climate change scenarios, RCP4.5 and RCP8.5. To do so, we apply a corrected bathtub algorithm. Additionally, we compute the impact of extreme storm surges and waves using two 35-year hindcasts consistently forced by mean sea level pressure and surface winds from ERA-Interim reanalysis. Waves have been further propagated towards the nearshore to compute wave setup with higher accuracy. The 100-year return levels of joint storm surges and waves are used to map the spatial extent of flooding in more than 200 sandy beaches around the Balearic Islands by mid and late 21st century, using the hydrodynamical LISFLOOD-FP model and a high resolution (2 m) Digital Elevation Model.&lt;/p&gt;

scholarly journals Threshold effects of hazard mitigation in coastal human–environmental systems

2013 ◽  
Vol 1 (1) ◽  
pp. 503-530
Author(s):  
E. D. Lazarus
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Human Activities ◽  
Environmental Changes ◽  
Hazard Mitigation ◽  
Coupled System ◽  
Time Frame ◽  
Global Scale ◽  
Coupling Mechanism ◽  
Environmental Systems

Abstract. Despite improved scientific insight into physical and social dynamics related to natural disasters, the financial cost of extreme events continues to rise. This paradox is particularly evident along developed coastlines, where future hazards are projected to intensify with consequences of climate change, and where the presence of valuable infrastructure exacerbates risk. By design, coastal hazard mitigation buffers human activities against the variability of natural phenomena such as storms. But hazard mitigation also sets up feedbacks between human and natural dynamics. This paper explores developed coastlines as exemplary coupled human–environmental systems in which hazard mitigation is the key coupling mechanism. Results from a simplified numerical model of an agent-managed seawall illustrate the nonlinear effects that economic and physical thresholds can impart into coupled-system dynamics. The scale of mitigation action affects the time frame over which human activities and natural hazards interact. By accelerating environmental changes observable in some settings over human time scales of years to decades, climate change may temporarily strengthen the coupling between human and environmental dynamics. However, climate change could ultimately result in weaker coupling at those human time scales as mitigation actions increasingly engage global-scale systems.

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