Articles

Exploring the Repositioning of Health, Extreme Hydrologic Events, and Global Change

Chrysanthus Chukwuma Sr
Executive Director, Dept of Future Studies, The Chrysanthus Centre for Future-oriented Studies, Abakaliki, Ebonyi State, Nigeria.

Received Date: 06 August 2024, Accepted Date: 13 August 2024, Published Date: 16 August 2024

*Corresponding author: Chrysanthus Chukwuma Sr, Executive Director, Dept of Future Studies, The Chrysanthus Centre for Future-oriented Studies, Abakaliki, Ebonyi State, Nigeria.

Citation: Chrysanthus Chukwuma Sr. (2024). “Exploring the Repositioning of Health, Extreme Hydrologic Events, and Global Change”. International Journal of Medical Research and Medical Case Reports, 1(2); DOI: http;/08.2024/ijmrmcr/007.

Copyright: © 2024 Chrysanthus Chukwuma Sr. This is an open-access article distributed under the terms of the Creative Commons Attribution 4. 0 international License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract:
Climate change imposes a tremendous impact on global technology due to a warmer climate resulting in grave morbidity and mortality in the near future from risks, such as extreme hydrologic events, heat, diarrhea, malaria, emerging and reemerging diseases as depicted on the health and healthcare spectra. The intrinsic challenge of the climate and hydrologic scientific, technical and research milieu is understanding or elucidating the characterisation of the changes in climate and hydrology as well as the perspicuous anomalies in reconciling extreme peculiarities as outcome of nature and anthropogenic activities. Increasing events have intensified future-oriented studies of the spatiotemporal variabilities in local, regional and global extreme precipitation and temperature. Evidentially, extreme hydrological events, EHEs, such as droughts and floods encounter spatiotemporal variations, with remarkable intensification and augmentation of extreme drought and precipitation. These are not mere perturbations of weather events but culminate in extremes, evidenced as depreciated agricultural produce, infrastructural excoriation, combined natural and anthropogenic entropy, crises and conflicts. Precipitation is a primordial ingredient of the hydrological cycle and a prime indicator of climate change. Climate change has overwhelmingly influenced extreme precipitation events with aggravated intensity and frequency, accompanied by an increased latitude for natural disasters. Thus, hydrological extremes as floods and droughts are critical natural and anthropogenic hazards. Extreme hydrometeorological events are drivers of hazardous hydrological and geomorphical  reactions, such as floods, landslides, and debris flows which constitute substantial global health threats to society which necessitate technological interventions. Hydrologic change emerge from a plethora of drivers which generally stress and transform hydrologic systems and water cycle. The direct stressors on hydrologic systems encompass expansive land-cover modification, urbanization, industrialization and stringent engineering interventions. There are projections that the hydrological cycle may intensify due to global warming because global warming accelerates mechanisms of the hydrologic cycle globally culminating in aggravated intense droughts and wet periods which impact on the health and sustainability of modern societies. The frequency and severity of hydrologic extremes have increased due to nature and human interference; thus, incessantly compromising critical natural events. Emanating from climate change, flash floods have increased, with projections to increase in the future. In essence, health, global change and extreme hydrology summarise this article.

Keywords: mortality; comorbidities; frequency analysis; global warming; dynamics; cardiovascular disease; flood; environment; climate change; agricultural productivity.

Introduction:
Climate change elevates the risk of morbidity and mortality due to increasing temperature, intensively frequent heavy rains and runoff, and the impacts of storms. Health effects may involve gastrointestinal, nervous, respiratory, liver and kidney disorders [1, 2]. The extant quantity of water pertaining as groundwater, rivers, lakes, streams and ponds may encompass a vast expanse, resulting in excess of available spread. This demonstrates the importance of the limited and treasurable characterisation of water, particularly freshwater. Water forms part of both the surface and inside of the Earth. Thus, water obliterates a preponderant surface of the Earth in comparison to the land mass. The water dominance paves the contour for climate, undergirds a bountiful biodiversity, and human civilization for sustainability. With the prevailing challenges of pollution, intense climate change, and extreme hydrologic events, it is pertinent to consider the conservation and sustainable management of our water resources for the future. This review provides current drivers and typologies of extremes in disparate geopolitical arenas with highlights, challenges, constraints, issues and opportunities in inter alia predicting and forecasting hydrological extremes spatiotemporally. Extreme hydrological events, such as floods and droughts, exert significant impacts on both anthropogenic and natural systems influencing health and healthcare. The duration, intensity and frequency of the events may alter as a consequence of climate change, therefore, creating and presenting opportunities for management and adaptation of water resources [1-3]. Within the context of climate change warming the atmosphere, the hydrology of the Earth shifts with propensity to cause floods and droughts in the extreme. It is pertinent for policy- and decision-makers to improve the understanding of prevailing transformations in hydrologic extremes in readiness for untoward changing events in health and the environments.

Characterisation of the hydrological cycle:

Hydrologic issues are  extreme events [4] associated with water presence, motion and hazards including flooding, droughts and correlated events, such as landslides, river scour and deposition. These act as a framework for sustainable and safe drinking-water and health in endpoint characterization variables regarding water consumption on human health[1]. Floods, limnic eruptions, and Tsunami are instances of hydrological disasters which pose as the most adverse climate change which affect the environment, human lives [5], and health as well as how they are significantly induced by wind and water. Hydrologic connotes water or the impact of water on the terrestrial ambient, with a devastating flood presenting as an instance of a hydrologic disaster. The hydrologic cycle comprises incessant water circulation in the terrestrial-atmosphere domain. The water cycle is the upward motion of water from the terrestrial and aquatic environments to the atmosphere, and its reversal to the terrestrial sphere. Therefore, the hydrological cycle of the earth encompasses all mechanisms whereby water moves from the terrestrial and aquatic surface upwards to the atmospheric conundrum, with transformation and reversal downwards as precipitation. Thus, the hydrological cycle is dependent on multiple factors including atmosphere, land and maritime surfaces. Hydrologic activity, such as the response, action and impact of water on other natural resources emerge in diverse morphological interactions as erosion, freezing and thawing as well as catastrophic events like tornadoes, severe storms, hurricanes, tropical storms, floods, wildfires, earthquakes and droughts. Hydrological conditions are instances which determine the spatiotemporal dissemination of floral species in wetlands, wherein water depth and hydrological fluctuations predictably impact the interspecies interactions of manifest wetland species. Hydrological processes, such as evaporation, transpiration, condensation,  precipitation and runoff are the most crucial aspects of the water cycle. Runoff related to varied trajectories whereby liquid water meanders across land. Snowmelt is an aspect of emergent runoff as snow or glaciers thaw into streams or pools. Inasmuch as the overall quantity of water in the cycle is invariably constant, its dissemination within diverse mechanisms changes incessantly.

Defining hydrological extremes and events in health:

The health impacts related with climate-correlated changes in extreme events exposure include morbidity, mortality and aggravated underlying medical condition[1]. This study entails hydrological extremes in the past and the future. Changes in hydrological extremes have been examined by means of  disparate observations, investigations and modeling datasets. Climate change and impacts on hydrological extremes and their attendant risks have undergone evaluation regionally and globally. The natural consequences of climate on the changes in hydrological extremes must be observed disparately from those impacts due to anthropogenic activities which affect health [6, 7] by utilising integrated impact models with a view of the uncertainties in hydrological extremes across datasets and models. Insights into these challenges, issues and opportunities may identify and expose vulnerable regions and develop effective and efficient adaptation modalities regarding future climate change globally.

Despite technological progress and intensive research, the risk of weather-associated disasters defies eradication, and remains well-nigh impossible. Annually, disasters are becoming both more frequent and more destructive, causing material and pecuniary losses, as well as several thousand mortalities globally. Furthermore, hazardous weather events constitute the aegis of an accelerated upward trend, as the extent of material dissipation heighten by an unprecedented extent in inflation-adjusted pecuniary terms.  Increasing evidence of extant planetary climate change or gobal warming has caused pronounced modifications regarding extreme hydro-meteorological events, with potential outcome in expansive remarkable alterations. Empirically, changes in extremes are  astronomically evident, exerting more impact than mean value changes. The rising extremes include the evidenced hot days and tropical nights, duration, heatwave intensity,  as well as precipitation intensity with resultant floods, landslides and mudflows; drought frequency, severity and duration; thawing of glacier and snow, intensity of tropical cyclone, as well as surging of sea level and storms. There is projected ubiquitous decrement in cold extremes, such as number of cool days and nights, including frost days. Increased climate extremes associated with climate change may precipitate physical infrastructural impairment and human  displacement, excruciating and adverse impacts on agricultural produce as well as fresh water quality and availability [8].

Exploring droughts and floods:

Although, the World Health Organization (WHO) regards flood as a risk factor in the transmission of cholera, drought is not explicitly recognized[1, 6, 7]. Naturally, extreme hydrological events, EHEs, such as droughts and floods exhibit spatiotemporal variations. Increased events in recent decades have intensified research of the spatiotemporal variability of future extreme precipitation and temperature. Research of the implications on the EHEs as a result of the uncertainty of predicted climate changes, necessitates detailed spatiotemporal analysis of precipitation and temperature. Also, for optimum planning and decision-making mechanism to tackle EHEs, elucidating these climate changes necessitates further information to enhance elucidation of spatiotemporal analysis of extremes [9].

Drought has gained prominence due to its occurrence over a continental scale with protracted duration of decades [10, 11]. Although, certain floods are localized with limited  duration, others can overwhelm a basin for a duration of one month. In nature, these hydrological events oppose each other but they are not exceedingly mutually exclusive due to their occasional simultaneous occurrence. The misleading, misinterpreting and omitting in statistics of the probability of extreme events in drainage design codes may culminate in inchoate capacity of drainage systems. This is one of the main aetiologies of floods frequency, particularly in coastal habitats [12].

East Africa presents an intricately-complex hydrologic, climate and socio-economic context, susceptible to climate change-induced hydrological extremes.  Droughts and floods remain the principal regional challenges. Currently, incessant modifications across droughts and floods have frequently occurred and of common concern. There are extant heterogeneity of extremes, and climate change impact augmentation in intensity and duration of extremes. The significance of local and antecedent presentations in transforming the characterisations of extremes is vital to explicate drivers and interactions. Observational and modeling tools must harness the associations and extremes on brief timescales. Inasmuch as, there are improved forecasting regarding the extremes, the availability of inter alia expedient information and meteorological variables necessitates future studies [13].

Nowadays, extreme hydrological events such as inter alia flash floods, droughts, and severe storms intensely impact on the global economic, environmental, and social systems [14]. Acquisition of vital and practical information to plan and manage regional water resources, assess risks of hydrological events, decrease and adapt to climate change impacts. It is needful to evaluate, estimate, assess and analyse trends of extreme hydrological events as  nonparametric and parametric. Nonparametric tests are in greater application than parametric tests because development of parametric methods are based on assumptions of normality, static, and time series independence, whereas these assumptions are not satisfactorily ubiquitous in a hydrological time series, but nonparametric methods are applicable in linear and nonlinear time series.

Precipitation and climate change:

Invariably, change in precipitation or climate  impacts human health. Elevated temperatures and wildfires, and diminishing precipitation may culminate in rising ozone and particulate matter, with aggravated cardiovascular risks. However, certain populations have more vulnerability to the health impacts of climate change [1]. Precipitation is a vital aspect of the hydrological cycle and a key climate change indicator [15]. Due to climate change, extreme precipitation events have increased globally and regionally in frequency and intensity, with tendency to a higher probability of natural disasters [16]. Extreme rainfall and floods have increased in frequency and severity due to climate change and urbanization, with resultant estimation and assessment of the probable maximum precipitation, PMP [17]. Climate theory pertains that core components of the climate system, such as precipitation, evapotranspiration, and reservoirs of atmospheric and soil moisture, alter as the climate warms, regarding means and extremes.

The hydrological cycle is projected to intensify with global warming, with the potential of exacerbating the intensity of extreme precipitation events and flooding risk. However,  the changes usually present differently from the proposed augmentation in the atmospheric water‐holding capacity in warmer conditions, particularly during restricted water availability. The association of changes in extreme precipitation and flood intensities in terms of the termination of the 21st Century with quantification of spatiotemporal water availability [18]. Intensified extreme precipitation and flood events encompassing every climate region increases concurrently with enhanced water availability from dry to wet regions. Pari passu, increased intensity in extreme precipitation and flood with the seasonal cycle of water availability prevails. The association between extreme precipitation and flood intensity changes, while spatiotemporal water availability persists with less extreme events [19].

The probability estimates of an extreme hydrological event, for instance, an uncommon low flow or drought, and the concurrent reverse phase related to the event are vital for water resource design, management, prediction,  and projection. Frequency analysis of erstwhile events is an established tool for the severity assessment of an extreme event and the probability  in the future per occurrence of the event. Estimate of a design event focuses on the lower or upper tail of the probability distribution, where  observations are seldom detectable,  implying broad uncertainties in estimation. There are, however, limited options in operational practice, and possibly, increasingly crucial is the realisation of innate restrictions in the procedure [20].

Climate vulnerability has tended to focus on the anthropogenic inducements on climate change and global warming, frequently excluding superimposable threats, such as carbon dioxide emissions, population growth and the stress on energy sources  accrued from emerging global affluence [21, 22] and deteriorating health. It is expedient to evaluate the encompassing range of threats employing the bottom-up strategy on vital resources of food, ecosystems [23], energy, human health [24, 25] and water as well as  configuring the threats, deciphering preventive approaches and adaptations.

Adaptation to extreme hydrological events aids in catastrophic risk management and health:

The disaster risk management strategy for a changing climate integrates the management of extreme and slow-onset events via near-, medium-, and long-run risk decrement and adaptation process in ardent collaboration with public and private sectors of production as well as other stakeholders. The involvement in health and disaster management engage critical perspicacious emerging and reemerging health and developmental threats which tend to excoriate organizational capacity and sustainability[24, 25]. The association of coping, coping capacity, adaptive capacity, and the coping range [26] as well as adaptation to climate change impacts have undergone intensive assessment. Incontrovertibly, it is pertinent to assess the diversity in practices, options, challenges, issues, constraints, opportunities and capacity for effective, efficient and sustainable adaptation [27].

Extreme events in current climate conditions may be ubiquitous or scarce within future climate presentations. Elucidating the indicators of vulnerability and adaptive capacity are  vital to implement  proper adaptation modalities [28].

Adaptation in human systems correlates to the adjustment mechanism to real or expected climate with its impacts to moderate hazard or explore efficient and effective opportunities. Within natural systems, the adjustment mechanism to the real climate, its impact and anthropogenic intervention [29-31] can induce adjustment to the climate expected.

Within the local, regional or global scales, the extant inequitable influence of coping strategies and adaptive capacity may present further adaptation challenges and constraints as well as impediment to disaster risk management. Climate change adaptation processes are important  and sustainable for both decrement and management of risks due to extreme hydrological events. In pertinence to adaptation [32], the adjustment strategies to actual impacts and the expected impacts of climatic extremes entail adaptation. This is the scenario considering as these modalities are directed to mitigate, moderate and ensure beneficial explotation of presenting opportunities. Understanding exposure and vulnerability parameters constitute prime aspects for effective mechanisms in the adaptation to climatic extremes, mainly as a risk management trajectory to ameliorate vulnerability. Essentially, adaptive procedures invariably provide both short- and long-run benefits and opportunities.

Even though, climate change adaptation modalities are extant globally, adaptation interests in the risks of hydrological extreme prevail because adaptation is a more confounding venture [33]. This is attributed to the justifiable pertinence of adaptation as the occurrence of droughts and floods is increasingly perturbed by innate complexity and uncertainty. This may also explicate the confounding stance in adaptation attributable to the role of contextual cases which are frequently impaired by extensive variations of local vulnerabilities and disparities in policies and economic variables. A superimposed explanation for the confounding adaptation relates to the mode of adaptation regarding both policy and institutional mechanisms employed for the realisation of adaptation modalities. Amelioration initiatives target global phenomena but adaptation initiatives relate to local responses to issues  which are prevalent and experienced globally.

There are variations in climate change adaptation locally, regionally and globally. These highly depend on the vulnerability,  susceptibility and sensitivity to environmental effects.  It is expedient to adapt to the increasing occurrence and extremity of floods and droughts, otherwise, enhanced socio-economic dissipations will result [34]. Flood risk management via adaptation will be more effective with the utilisation of an integrated approach.  A combination of adaptive approaches, such as flood control infrastructure, an insurance risk financing scheme, and nature-based remedies may offer essential integration. There are spatial variations in the integration of disparate adaptation modalities. The variations are influenced by  prevailing risk levels, political benefits and pecuniary potential [35].  Flood control infrastructure may constitute strategies for adaptation to the extreme flood events, whereas traditional structural controls tackling floods have been ineffective, particularly when extreme and rare events are increasingly inimical, also with subversive inpact on the flood control structures. Instances of residual risks due to flood control dam inadequacies are evidenced globally,  thus exposing  the limitations of employing structural risk decrement procedures which augment the issues during extreme events.

Adaption to climate change inculcates optimistic procedures directed to the preparation and adjustment to present and future extreme events and the culminating  environmental impacts. Adaptation of droughts and floods as the major hydrological extreme events necessitate that both formal and informal institutional arrangements are available to facilitate the adaptive mechanisms; wherein,  the informal arrangements have remarkably facilitated community collective actions in contradistinction to formal institutions [36]. Also, the enabling functions in adaptation characterisations and implementation, policy frameworks are formidable accoutrements operated by governments as enabling milieu for functional institutional arrangements. Adaptation practices regarding droughts include enhancement of water supply and demand aspects mechanisms for water efficiency. The essence and integrity for incremental adaptation initiatives  concern the maintenance of the system. The transformational adaptation strategies target the basic characterisations of a system in responding to climate change and the resultant deleterious impacts. Drought and flood early warning systems function as the adaptation mechanisms, essentially deployed to drive or mobilise extreme adaptation measures.

Dryland Rivers and streams associated with food web dynamics:

Climate change influences availability, quality and diversity of food, spiking food and nutrition crises. The standard strategies to interprete, explicate and understand the presenting indicators for river health in variable systems[20, 30, 31]. As a result of the extreme hydrological variability and opportunistic biotic responses to flood pulses, dryland rivers are amenable to specific food webs. In these systems, primary productivity and heterotrophy are vital for food web sustenance [37, 38]. Due to flows which provide rewetting and upstream delivery, there are episodic particulate and dissolved resources, and autochthonous formation frequently occurs remarkably, and within a brief period generates an extensive biomass [39]. The biomass preponderance can culminate in elevated quantities of secondary production.

Frequently, consumers in dryland systems are  generalists with  adaptations for the exploitation of pulses in resources concomitantly with modifications in resource presentations. A vast majority of dryland river consumers have characterisations which alternatively permit them to harness an expansive range of resources or persist awaiting sustainable conditions and resources. The extant interactions in dryland rivers are tightly bonded due to adaptations to variable flow regimes periodically characterized by nadir flow and drying. Organisms in perennial streams are susceptible to fauna devastation during droughts with resultant trophic rewiring [40]; conversely, organisms in dryland rivers adapt to prolonged drying periods. It is evident that food webs in these systems are restricted within these periods, but core ecological interactions endure, culminating in similar topologies as food webs consumers [41] in the precinct. Furthermore, aquatic consumers in dryland rivers do depict relatively stringent trophic interactions to terrestrial food webs; partly due to ardent production of intensive linkages with terrestrial systems. It is supposed that aridity augments terrestrial consumer responses to water proliferation, thus in drylands referring to water as a trophic currency [42, 43],  a unit of value to determine species interactions in terrestrial food webs. This suggests that dryland river food webs portray resistant multiscale backbones [44] which undergird the persistence of core ecological functionalities in these systems during drought.

Tolerance to Flooding and Submergence:

Root health is crucial for crop survival during flooding. In rice, augmenting flooding tolerance necessitates combined tolerance of submergence and of stagnant flooding. Agricultural areas are vulnerable to flooding and ponding due to the augmented excessive precipitation and hydrologic extremes. Within this milieu, plant breeders strive to identify and develop genetic technologies to promote crop productivity. Rice constitutes a veritable instance in breeding regarding crop tolerance [45] to flooding. A vast majority of rice cultivars can merely tolerate flooding for circa one week, but a class of ethylene-response-factor-like genes have been identified which play a role in flooding/submergence tolerance [46]. Ethylene accumulation retards cytokine-mediated senescence and induces dormancy in submergence.

Climate impacts and concomitant environmental susceptibilities are limned as multifarious  entities. Instances of multiple environmental stresses are excess heat, flooding, drought, and elevated soil salinity [47]. Enhanced frequency of these stresses  influence crop yields untowardly in excess of the impacts of alterations in mean temperature and precipitation, as well as aggravate the latitude of agricultural produce when vying with numerous and diverse stresses spatiotemporally. Agriculture will not preponderate the future transformations of crop species with tolerances to select abiotic stress variables associated with climatic events. Plant breeders are confronted with the constraints of integrating  or piling multiple abiotic stress tolerance traits or components into every novel cultivar to offer tolerance to an expansive spectrum of excruciating climate spheres. These constitute arduous tasks because stacking multiple genes into a sole elite cultivar necessitate to combine the time for the pertinent breeding cycles, information, knowledge and understanding of trait interaction for productivity maximization.

Challenges for sustainable land and water management:

Drinking water, food and energy security, climate change, water-borne diseases, water-related disaster management as well as maintainance of sustainable environmental quality and land use management are certain present and future major challenges[1, 2, 6, 7].

Land use change has produced realistic impacts on hydrological extremes, such as aggravating dry or wet ambient, and a lackadaisical future trajectory that may superimpose on the risk [48]. A progressive culture of soil sealing from urban sprawls, megacities and giant industries is in the ascendancy, and  Its hydrologic impacts on flood frequency have been established [49]. Additionally, soil sealing drives the dissipation of diverse ecosystems which are vital for lowland communities, such as biodiversity, agricultural produce, water absorption, soil filtering and buffering capacity. Furthermore, there emerges dissemination of  environmental issues of cities, such as atmospheric- or light-pollution expansively present in different areas, impeding effective impact.

Future land use plan must target increased resilience of lowland communities to hydrologic extremes. Due to increasing unpredictability and intensity of climate presentations, in dryness and wetness, it is imperative to improve the landscape buffering functionality. Improved rainwater and surface water retention in the course of a catchment, attenuated peak flow is tenable while water supply is augmented during drought. Sustainable land and water management [50] must embrace all aspects of the landscape to promote water storage in agricultural areas [51] and ditches, including infiltration in urban contexts, or retention in the course of major rivers for the protection of the unique, precious, albeit delicate lowlands.

An extant challenge for sustainable land and water management and in climate adaptation and mitigation projects is the recognition of Sustainable land management (SLM) as key to diminished land degradation rates, and desertification obliteration, with assurance for greener and more sustainable future, and concerted keeping of the faith to circumvent issues and challenges such as water scarcity, pollution, ecosystem cadastral [23] devastation and untoward environmental health measures[31].

Objectives of hydrological frequency analysis:

Hydrological frequency analysis (HFA) relies on a number of assumptions on the data series, especially independence, homogeneity and stationarity. Severe economic and social repercussions may emanate from extreme hydrological events, such as floods, droughts, and storms. Numerous studies specifically adhere to either event with disparate approaches and select regions. In water resources management, drought is paramount, whereas extreme precipitation and flood estimates constitute the formulation of hydraulic and hydrologic structures. Understanding the characterisations inextricably-linked with these extreme hydrological events is crucial for accurate assessment of the risk in the design and operation of water infrastructures. An inadequate assessment of design floods culminates in material and  human life disruption. An overestimation results in over-sizing of hydraulic structures inculcating supplementary costs. It is fundamental to undertake the warranted models for appropriate and accurate prediction of these events [52]. Hydrologic extreme events are not estimable, predicted, or merely conducted on deterministic information with adequate skill and lead time [53]. Rather, a probabilistic trajectory is pertinent to inculcate the impacts of such events into decisions. On the presumption that successive events are independent in timing and magnitude, hydrologic frequency analysis is deployable as a decision tool through estimable presenting event or a combination of events. Certain engineering tools utilise, hydrologic frequency analysis, HFA such as hydraulic and municipal structure design per culverts and storm sewers as well as evaluation of landslide hazard.

Mechanisms in hydrologic extremes and variabilities:              

Extreme weather events due to the ENSO cycle can affect population health through the associated droughts, floods, heat waves, and disruptions in food ... The health risks of climate change arise from the interactions of the hazards associated with a changing climate (e.g. increases in the frequency and intensity of extreme weather and climate events, such as drought), the communities exposed to those hazards, the susceptibility of communities to adverse health impacts when exposed, and the capacity to prepare for and cope with the hazard. Globally, there is an increasing incidence of hydrological extremes and variability; and from top-bottom multi-decadal model predictions, the future climate will contain elevated moisture concentration. The increased water-holding capacity of the atmosphere may enhance the frequency of heavy precipitation events, as extreme precipitation is restricted by the atmospheric moisture concentration. The trend for increasing dry periods between rainfall events also pertains but  models are inconsistent in this aspect [54]. A protracted projection by climate models for increased dry summer in the mid-latitudes, with a concurrent enhanced probability of drought pertains [55, 56] There is projected aridity increase in soybean-growing regions in the Americas excepting northeast Argentina and Uruguay as well as Southeast Asia due to impacts of regional warming partly attributable  to human greenhouse gas emissions. Global net primary crop production will be diminished by 10%, and by 2050, the climate is expected with the SRES A2 emission scenario because of decline in regional precipitation, elevated temperatures resulting in increased agricultural water restriction and unrestrained crop degradation [57]. Increased carbon dioxide offsets [58] these deranging impacts, but the extent of the impact is not definite. Elevated atmospheric moisture level may ameliorate the warming impact on vapor pressure decrement that rises exponentially with temperature and drives transpirational water dissipation from plants, however, certain rise in evapotranspiration may inevitably transpire. Simulation studies are liable to overestimate high temperature impact on crop water use by neglecting vapour pressure increase [59]. Also, less abundant tillage and cover crops are employed to augment bulk density, organic matter content [60] and enhance soil volumetric water level and assist conservation of soil moisture [61]. Deeper rooting aided by osmotic root adjustment to undergird cell turgor, when tissue water potential depletes, is naturally positioned to improve transpiration and yield. Enhanced tolerance to aluminum, detected in toxic levels in lower soil horizons, correlates with drought tolerance in a slow-wilting genotype. Tolerance to aluminum correlated with citrate level in root tips, proposing that citrate discharge may be connected in aluminum exclusion in tolerant genotypes [62]. Breeding and genetic transformations for this trait may be of worth.

Improved water use efficiency may occur leading to elevated atmospheric carbon dioxide concentrations due to net photosynthesis being higher and transpiration lower because of diminished stomata conductance [63]. These two are contributory factors to yield proficiency in soybean, but decreased transpirational cooling results in higher leaf temperatures and deficits in leaf-to-air vapor pressure, accompanied by elevated transpiration and respiration, thus depreciating net profit of crop biomass. 

Nitrogen fixation is more sensitive to water deficiency  than several other mechanisms, such as photosynthesis, biomass production, transpiration, and nitrogen soil uptake. Elevated levels of nitrogen compounds,  ureides in water-stressed plants may indicate that nitrogen fixation is suppressed in the nodule through feedback regulation of nitrogenase activity [64]. Suggestively, protracted nitrogen fixation during water stress obliterates premature senescence [65] and improves HI, with resultant increased yield [66, 67] and profuse beneficial  improvement in trait and trend.

Extreme hydrological events and global warming:

Warmer temperatures and shifting weather patterns debilitate air quality, resulting in respiratory and cardiovascular health effects as well as asthma tic episodes. Expected increase in severity, quantity and number of Wildfires with climate change, prompt smoke and other untoward or unhealthy atmospheric pollutants. Extreme weather events invariably impact human health inflicting injuries, loss of human lives, diseases, and mental disorders, and comorbidities. The multidimensional trajectories of extreme hydrologic events tend to (i) superimpose on strategies to determine hydrological extremes and to relate the spatiotemporal trajectories; (ii) unravel nascent observations, datasets, and modeling tools to elucidate hydrological extremes; (iii) provide estimation and assessment of  changes in hydrological extremes, both droughts and floods; (iv) explicate attributes and characterisations of changes in hydrological extremes; and (v) grant projections, predictions and forecastings of hydrological extremes and societal impacts under global warming. Global warming preponderates average precipitation and evaporation, leading to frequent occurrence of extreme climate and hydrological events [68]. Within the context of climate warming, extreme climate and hydrological events frequently result [69]. Global warming aggravates the hydrological cycle and increases average precipitation and evaporation [70]. Concomitantly, precipitation variability may change, exerting direct effects on evaporation, runoff, and soil humidity. Indubitably, there is geopolitical convergence [71] of countries on the scientific basis of climate change but divergence persists on which country is the major culprit, how to identify and track emissions-decrement goals, and the rationale to compensate vulnerable geopolitical areas. Governments must prevent the global average temperature from rising by 1.5°C.

Discussion:
Increased severe storms, droughts, warming and rising oceans, species dissipation, insufficient food, aggravated health risks [31], poverty and displacement, and extreme hydrological events, such as floods and droughts, increase the risk of water disasters, which are resultant preponderant challenges and issues to human survival [72]. Frequency analysis is pertinent in the design and modelling of hydrological systems but is usually statistically restricted by the overall spatiotemporal observation period [73]. Notwithstanding, observing, understanding and modelling the hydrological extremes in a changing climate remain a challenge. Currently, preponderance of hydroclimatic observations are available due to accelerated technology development for the acquisition of land surface parameters that facilitate to explicate and model hydrological extremes. Conversely, hydrologists strive to elucidate extreme events through the improvement of physically-based models for an optimistic assessment of regional and global effects of hydrological extremes. Elucidation of hydrological extreme events is tenable through aggregation of datasets and hydrological models for the future.

Conclusion:
Climate change and the transforming trajectories of extreme weather have the capability to excoriate the potential of public health systems. This study adopts the risk assessment framework that addresses and focuses on vulnerability, impacts, and adaptation. The hydrological cycle has been predominantly impacted by climate change. Climate-induced hydrological extremes, such as floods and droughts, have preponderated within past decades, with the trajectory and trend perspicuously remaining unabated into the future. These hydrological extremes are the prime drivers of numerous natural disasters, with resultant health and economic depreciations and  infrastructural excoriations, as well as unprecedented future threats to anthropogenic activities due to  climate change. In these aspects, it becomes imperative to be fully aware of hydrological extremes and the impacts for risk management and strategic adaptation for the future. Thus, extreme weather events have been on the increased, and are correlated to global warming. Such weather events are likely to be contributary to and elevate the risk for an expansive spectrum of vector- and non-vector-borne diseases and infestations in animals, humans, and plants with resultant untoward sequelae.