Interdisciplinary assessment of sea-level rise and climate change impacts on the lower Nile delta, Egypt

Anthropogenic-induced environmental and ecological changes in the Nile Delta over the past half-century

Anthropogenic activities over the past half-century have had a negative impact on the wetland ecosystem in the Nile Delta, which provides essential provisioning and regulating services. Therefore, it is crucial to systematically investigate pollution levels and their ecological consequences at both spatial and temporal scales in order to promote sustainable development. In this study, data on metal pollution in the Manzala Lake were compiled through a systematic review of all published literature from 1968 to 2020. Additionally, agricultural data (including land use, pesticide and fertilizer usage, and discharge) and economic data for the same time period were collected to identify the main drivers of pollution. The results indicated an overall increasing trend in heavy metal concentrations during the study period. The average concentrations of metals, arranged in descending order, were as follows: Fe (15,115.5 μg/g) > Mn (722 μg/g) > Zn (115.4 μg/g) > Cu (65.9 μg/g) > Ni (62.5 μg/g) > Cr (58.1 μg/g) > Pb (54.1 μg/g) > Cd (4.7 μg/g) > Hg (0.1 μg/g). A linear regression model revealed that wastewater discharge, water reuse, and the use of pesticides and fertilizers are the main sources of heavy metal pollution in the Manzala Lake. Consequently, there has been a dramatic decrease in the biodiversity of fish and molluscan communities. The study also found a correlation between heavy metal pollution and socio-economic development, highlighting the urgent need for attention to the conservation, management, and sustainable development of the lake.

Evaluation of Food Security Based on Remote Sensing Data—Taking Egypt as an Example

Egypt, a country with a harsh natural environment and rapid population growth, is facing difficulty in ensuring its national food security. A novel model developed for assessing food security in Egypt, which applies remote sensing techniques, is presented. By extracting the gray-level co-occurrence matrix (GLCM) mean texture features from Sentinel-1 and Landsat-7 images, the arable land used to grow grain crops was first classified and extracted using a support vector machine. In terms of the classified results, meteorological data, and normalized difference vegetation index (NDVI) data, the Carnegie–Ames–Stanford approach (CASA) model was adopted to compute the annual net primary production (NPP). Then, the NPP yield conversion formula was used to forecast the annual grain yield. Finally, a method for evaluating food security, which involves four dimensions, i.e., quantity security, economic security, quality security, and resource security, was established to evaluate food security in Egypt in 2010, 2015, and 2020. Based on the proposed model, a classification accuracy of the crop distribution map, which is above 82%, can be achieved. Moreover, the reliability of yield estimation is verified compared to the result estimated using statistics data provided by Food and Agriculture Organization (FAO). Our evaluation results show that food security in Egypt is declining, the quantity and quality security show large fluctuations, and economic and resource security are relatively stable. This model can satisfy the requirements for estimating grain yield at a wide scale and evaluating food security on a national level. It can be used to provide useful suggestions for governments regarding improving food security.

Sustainability of the Water-Energy-Food Nexus in Caribbean Small Island Developing States

The sustainability of small island developing states (SIDS) of the Caribbean is fragile because of island size and topography, limited resources, population growth, natural disasters, and climate change. Current and projected sustainability in 2050 were assessed within the framework of the water–energy–food (WEF) nexus for 10 of 16 SIDS with the best databases. Values for each WEF sector below either Falkenmark indicators or regional averages were considered unsustainable (failing) for that sector. Overall, SIDS were considered unsustainable if they failed at least two of three sectors. Projected water sustainability for 2050 was based on population growth and climate change effects on precipitation and per capita water availability. All SIDS failed the food sector, and four failed the energy sector. Water was considered the ultimate control for long-term sustainability. Five SIDS currently fail the water sector, but all but the largest two SIDS are likely to fail this sector by 2050. The role of poor governance and associated lack of long-term planning for population growth, disasters, and climate change, adaptative management strategies, infrastructure investment with an emphasis on nature-based solutions, decentralized energy grids emphasizing renewable energy, and local food production are clearly impediments for reaching sustainability goals for Caribbean SIDS.

An In-Depth Analysis of Physical Blue and Green Water Scarcity in Agriculture in Terms of Causes and Events and Perceived Amenability to Economic Interpretation

An analytical review of physical blue and green water scarcity in terms of agricultural use, and its amenability to economic interpretation, is presented, employing more than 600 references. The main definitions and classifications involved and information about reserves and resources are critically analyzed, blue and green water scarcity are examined along with their interchange, while their causal connection with climate in general is analyzed along with the particular instances of Europe, Africa, Asia and the WANA region. The role of teleconnections and evaporation/moisture import-export is examined as forms of action at a distance. The human intervention scarcity driver is examined extensively in terms of land use land cover change (LULCC), as well as population increase. The discussion deals with following critical problems: green and blue water availability, inadequate accessibility, blue water loss, unevenly distributed precipitation, climate uncertainty and country level over global level precedence. The conclusion singles out, among others, problems emerging from the inter-relationship of physical variables and the difficulty to translate them into economic instrumental variables, as well as the lack of imbedding uncertainty in the underlying physical theory due to the fact that country level measurements are not methodically assumed to be the basic building block of regional and global water scarcity.

Morphological consequences of upstream water and sediment changes and estuarine engineering activities in Pearl River Estuary channels over the last 50 years

The relative contributions of decreased upstream sediment loads and local estuarine engineering activities to the estuarine channel geometry are poorly understood. In this study, we analyze the hydrological changes and identify the location, duration and intensity of the estuarine engineering activities based on the channel morphologic changes from 1965 to 2017 at the five stations in the Pearl River Estuary. Thereafter, the Mann-Kendall (M-K) statistical test, empirical orthogonal function (EOF) tests, and channel geometry reconstruction based on the hydrological coefficient were performed to quantitatively estimate the relative contributions from upstream dam construction and estuarine engineering activities. The results show that the geometric changes in the five transects over the last 50 years could be divided into three stages. Stage I extends over approximately 23-33 years at the different channel transects, during which the channel geometries were mainly influenced by natural factors, with a balance between erosion and deposition. Stage II occurred during the next 11-20 years and the changes in the cumulated water depth in comparison to the values in the previous adjacent years at this stage are approximately 5-25 times the values in stage I. The human activities (e.g., sand excavation) contribute to >70-90% of the extreme geometric changes. Stage III lasted for <3-11 years in the different transects with a slight depositional trend, and policies regulating sand excavation were implemented during this stage. The rapid increase in the channel area and water depth caused by sand excavation can cause the downcutting of the riverbed, a decrease in the water level, and redistribution of the water and sediment discharge. Therefore, the monitoring, simulation and analysis of the variation in the typical channel geometry over the long term provide important means to understand the human activities occurring and insights for future sustainable estuarine management.

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

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.

High-Resolution Climate Projections for a Densely Populated Mediterranean Region

The present study projected future climate change for the densely populated Central North region of Egypt (CNE) for two representative concentration pathways (RCPs) and two futures (near future: 2020–2059, and far future: 2060–2099), estimated by a credible subset of five global climate models (GCMs). Different bias correction models have been applied to correct the bias in the five interpolated GCMs’ outputs onto a high-resolution horizontal grid. The 0.05° CNE datasets of maximum and minimum temperatures (Tmx, and Tmn, respectively) and the 0.1° African Rainfall Climatology (ARC2) datasets represented the historical climate. The evaluation of bias correction methodologies revealed the better performance of linear and variance scaling for correcting the rainfall and temperature GCMs’ outputs, respectively. They were used to transfer the correction factor to the projections. The five statistically bias-corrected climate projections presented the uncertainty range in the future change in the climate of CNE. The rainfall is expected to increase in the near future but drastically decrease in the far future. The Tmx and Tmn are projected to increase in both future periods reaching nearly a maximum of 5.50 and 8.50 °C for Tmx and Tmn, respectively. These findings highlighted the severe consequence of climate change on the socio-economic activities in the CNE aiming for better sustainable development.

A system dynamics model to quantify the impacts of restoration measures on the water-energy-food nexus in the Urmia lake Basin, Iran

Water scarcity exacerbated by growing demand in different sectors has created environmental, social, and economic challenges in the Urmia Lake Basin, Iran. Tackling this problem requires an integrated approach considering the basin as an interconnected system where a change in one sector affects others. Here, a System Dynamics Model is developed to simulate the water-energy-food nexus in the Urmia Lake Basin as a holistic multi-sectoral system and to assess the impacts of proposed lake restoration measures, especially looking for trade-offs. Besides considering climate change impacts, the effect of different sets of measures including increasing irrigation efficiency, increasing return flows, inter-basin water transfers, crop land retirement, and reviving a portion of the lake on the natural resources and socio-economic state of the basin are analysed. Results show that Urmia Lake level is sensitive to climate change scenarios. A holistic restoration approach could be effective in increasing the lake level to the proposed ecological level by 2040. However, in doing so, electricity demand in the agricultural sector could grow significantly. It is shown that a 20% retirement of irrigated wheat lands to curb water demand, if coupled with a 20% increase in yield on 80% and 50% of irrigated and rain-fed fields respectively, will not reduce wheat production in the basin. The effectiveness of water demand management measures is highly dependent on continuous monitoring and enforcement, particularly in restricting growth in agricultural water consumption. This study considered all nexus sectors in a holistic way to assess the total impact of proposed measures which on paper look positive, but may have unexpected consequences such as increasing energy demand for electric pumps. In dialogue with Urmia Lake restoration practitioners, this work can feed in to inform effective decisions for the restoration of Urmia Lake.

Risk of extreme events in delta environment: A case study of the Mahanadi delta

Anthropogenic climate change is considered as one of the greatest environmental, social and economic threats to the future world. Low lying deltas all over the world are increasingly subjected to multidimensional risk of sea level rise, cyclone, surges and salinisation. The life and livelihood of the communities of such deltas are endangered due to climate change acting as risk multiplier. The Mahanadi delta in the state of Odisha, India is one of the such populous deltas with estimated 8 million population in 2011 with a density of 613 persons/km². Over the past decades, it experienced major climatic threats in the form of cyclone, surge inundation and flooding with variable intensities and impacts along and across the coast. The present research assessed the risk of climatic extreme events and their variability in the delta, with an intention of mitigation or adaptation to possible impacts in specific region. Synthetic Aperture Radar (SAR) data and daily rainfall data were used to extract flood inundation. Tropical Cyclone Risk Model (TCRM) along with surge decay function was used to estimate cyclonic wind speed and surge inundation and risk indices were computed using fuzzy logic based approach. The result shows that in the coastal districts, risk of severe cyclones rank above the heavy floods. Agriculture, the main livelihood of these districts (71%) is impacted adversely making the delta community vulnerable to such extreme events. Kendrapara followed by Bhadrak and Jagasinghpur districts appear to be most risk prone segment in the delta making the northern part comparatively more risk prone where focused mitigation and adaptation actions are needed.

Simulating climate change and socio-economic change impacts on flows and water quality in the Mahanadi River system, India

Delta systems formed by the deposition of sediments at the mouths of large catchments are vulnerable to sea level rise and other climate change impacts. Deltas often have some of the highest population densities in the world and the Mahanadi Delta in India is one of these, with a population of 39 million. The Mahanadi River is a major river in East Central India and flows through Chattisgarh and Orissa states before discharging into the Bay of Bengal. This study uses an Integrated Catchment Model (INCA) to simulate flow dynamics and water quality (nitrogen and phosphorus) and to analyze the impacts of climate change and socio-economic drivers in the Mahanadi River system. Future flows affected by large population growth, effluent discharge increases and changes in irrigation water demand from changing land uses are assessed under shared socio-economic pathways (SSPs). Model results indicate a significant increase in monsoon flows under the future climates at 2050s (2041-2060) and 2090s (2079-2098) which greatly enhances flood potential. The water availability under low flow conditions will be worsened because of increased water demand from population growth and increased irrigation in the future. Decreased concentrations of nitrogen and phosphorus are expected due to increased flow hence dilution. Socio-economic scenarios have a significant impact on water quality but less impact on the river flow. For example, higher population growth, increased sewage treatment discharges, land use change and enhanced atmospheric deposition would result in the deterioration of water quality, while the upgrade of the sewage treatment works lead to improved water quality. In summary, socio-economic scenarios would change future water quality of the Mahanadi River and alter nutrient fluxes transported into the delta region. This study has serious implications for people's livelihoods in the deltaic area and could impact coastal and Bay of Bengal water ecology.

The use of cartographic modeling to assess the impacts of coastal flooding: a case study of Port Said Governorate, Egypt

Low-set coastal areas are expected to aggravate inundation on account of sea level rise (SLR). The present study is planned to appraise the impacts of coastal flooding in Port Said city, Egypt by using remote sensing, GIS, and cartographic modeling techniques. To accomplish this scope, Landsat 8-OLI image dated 2016 and SRTM 1Arc-Second Digital Elevation Model (DEM) data were used. Landsat image was classified into seven land use and land cover (LULC) classes by using remote sensing and GIS's software. Different inundation scenarios 1.0, 2.0, and 3.0-m coastal elevation were used to figure the influence of SLR on the study area. Estimation of potential losses under SLR was made by overlaying the expected scenarios on land use. The inundation areas under the expected SLR scenarios of 1.0, 2.0, and 3.0 m were estimated at 827.49, 1072.67, and 1179.41 km², respectively. In conclusion, this study demonstrated that expected coastal flooding scenarios will lead up to serious impacts on LULC classes and coastal features in the study area.