An Assessment of the Hydrological Trends Using Synergistic Approaches of Remote Sensing and Model Evaluations over Global Arid and Semi-Arid Regions

Abstract

Drylands cover about 40% of the world’s land area and support two billion people, most of them living in developing countries that are at risk due to land degradation. Over the last few decades, there has been warming, with an escalation of drought and rapid population growth. This will further intensify the risk of desertification, which will seriously affect the local ecological environment, food security and people’s lives. The goal of this research is to analyze the hydrological and land cover characteristics and variability over global arid and semi-arid regions over the last decade (2010–2019) using an integrative approach of remotely sensed and physical process-based numerical modeling (e.g., Global Land Data Assimilation System (GLDAS) and Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System (FLDAS) models) data. Interaction between hydrological and ecological indicators including precipitation, evapotranspiration, surface soil moisture and vegetation indices are presented in the global four types of arid and semi-arid areas. The trends followed by precipitation, evapotranspiration and surface soil moisture over the decade are also mapped using harmonic analysis. This study also shows that some hotspots in these global drylands, which exhibit different processes of land cover change, demonstrate strong coherency with noted groundwater variations. Various types of statistical measures are computed using the satellite and model derived values over global arid and semi-arid regions. Comparisons between satellite- (NASA-USDA Surface Soil Moisture and MODIS Evapotranspiration data) and model (FLDAS and GLDAS)-derived values over arid regions (BSh, BSk, BWh and BWk) have shown the over and underestimation with low accuracy. Moreover, general consistency is apparent in most of the regions between GLDAS and FLDAS model, while a strong discrepancy is also observed in some regions, especially appearing in the Nile Basin downstream hyper-arid region. Data-driven modelling approaches are thus used to enhance the models’ performance in this region, which shows improved results in multiple statistical measures ((RMSE), bias (ψ), the mean absolute percentage difference (|ψ|)) and the linear regression coefficients (i.e., slope, intercept, and coefficient of determination (R2)).

Influence of phase change materials on thermal comfort, greenhouse gas emissions, and potential indoor air quality issues across different climatic regions: A critical review

“…Under the BWh climate, the mean annual precipitation levels are normally >18 mm, and evapotranspiration is low during summer (June and July) and rarely occurs during spring and winter 99 . In this study, cities that are found under BWh climate are Doha (Qatar), Al‐Kut (Iraq), Ouargla (Algeria), Ghardaia (Algeria), and Khartoum (Sudan) (refer to Table 2).…”

“…Under the BWh climate, the mean annual precipitation levels are normally >18 mm, and evapotranspiration is low during summer (June and July) and rarely occurs during spring and winter. 99 In this study, cities that are found under BWh climate are Doha (Qatar), Al-Kut (Iraq), Ouargla (Algeria), Ghardaia (Algeria), and Khartoum (Sudan) (refer to Table 2). In Doha (Qatar), living rooms built with PCM tiles in an environment with a high ambient temperature (32.8 C-43.0 C), and intense solar radiation levels of 841 W/m 2 were studied.…”

“…BSk climates normally have low mean annual precipitation levels of <18 mm, with the highest evapotranspiration levels occurring during summer (June-August)and the lowest in winter (December-January). 99 As indicated in Table 2, the main cities with a BSk climate are Kokshetau (Kazakhstan), Tehran (Iran), and El Bayad (Algeria). Adilkhanova et al 78 2).…”

Impact of aridity rise and arid lands expansion on carbon‐storing capacity, biodiversity loss, and ecosystem services

“…Thus, agriculture in arid lands generally uses crops which are more adapted or resistant to drought (Ihsan et al., 2016), expanding and using smart irrigation systems (Romdhane et al., 2020; Yu et al., 2021), using fertilizers (Dar et al., 2021), changing tillage practices (Shemdoe et al., 2009), and using transgenic genotypes (de la Pena & Pueyo, 2012). However, food production in many drylands globally has been significantly affected by aridification and desertification, which is especially problematic in regions such as the African continent where human populations still show high rates of growth (Elagib, 2014; Li et al., 2020). Predicted shifts from temperate to subtropical drylands, including changes such as the loss of temperature‐controlled seasonal cycles, phenological shifts, increases in frost‐intolerant species, and the dominance of C4 over C3 grasses, may render the cultivation of certain crop species economically unviable in some areas (Schlaepfer et al., 2017).…”

“…However, food production in many drylands globally has been significantly affected by aridification and desertification, which is especially problematic in regions such as the African continent where human populations still show high rates of growth (Elagib, 2014;Li et al, 2020). Predicted shifts from temperate to subtropical drylands, including changes such as the loss of temperature-controlled seasonal cycles, phenological shifts, increases in frost-intolerant species, and the dominance of C4 over C3 grasses, may render the cultivation of certain crop species economically unviable in some areas (Schlaepfer et al, 2017).…”