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Freshwater salinization is receiving increasing global attention due to its profound influence on nitrogen cycling in aquatic ecosystems and the accessibility of water resources. However, a comprehensive understanding of the changes in river salinization and the impacts of salinity on nitrogen cycling in arid and semi-arid regions of China is currently lacking. A meta-analysis was first conducted based on previous investigations and found an intensification in river salinization that altered hydrochemical characteristics. To further analyze the impact of salinity on nitrogen metabolism processes, we evaluated rivers with long-term salinity gradients based on in situ observations. The genes and enzymes that were inhibited generally by salinity, especially those involved in nitrogen fixation and nitrification, showed low abundances in three salinity levels. The abundance of genes and enzymes with denitrification and dissimilatory nitrate reduction to ammonium functions still maintained a high proportion, especially for denitrification genes/enzymes that were enriched under medium salinity. Denitrifying bacteria exhibited various relationships with salinity, while dissimilatory nitrate reduction to ammonium bacterium (such as Hydrogenophaga and Curvibacter carrying nirB) were more inhibited by salinity, indicating that diverse denitrifying bacteria could be used to regulate nitrogen concentration. Most genera exhibited symbiotic and mutual relationships, and the highest proportion of significant positive correlations of abundant genera was found under medium salinity. This study emphasizes the role of river salinity on environment characteristics and nitrogen transformation rules, and our results are useful for improving the availability of river water resources in arid and semi-arid regions.

[Objective]Water supply is the determinant factor restricting the development of arid and semi-arid areas.Therefore, scientific evaluation of the water-holding performance of typical stands in arid and semi-arid areas is an important basis for planning shelterbelt construction, regulating stand structure and selecting tree species.[Methods]Five typical plantation forests in Ordos Afforestation Field in Kubuqi Desert were taken as the research objects.The water-holding performance of canopy, understory vegetation, litter and soil layers were analyzed by field harvesting method and indoor immersion method.The fuzzy matter-element model was introduced to quantitatively evaluate the water-holding performance of different forest stands combining with European-style closeness.[Results](1)The canopy water-holding capacity of different tree species was significantly different, showing as the order:dry willow and poplar mixed forest＞elm forest＞poplar forest＞salix forest＞Pinus sylvestris forest, and the stand water holding capacity was between 2.36～9.98 t/hm².(2)The water holding capacity of understory vegetation in each stand was between 0.84～3.66 t/hm², and the biomass was between 1.33～3.92 t/hm².The biomass showed the same trend as the water holding capacity.(3)The water holding capacity of litter was between 1.96～29.25 t/hm², and the biomass was between 1.43～13.62 t/hm².The logarithmic function and power function could better describe the dynamic water holding capacity and dynamic water absorption rate of litter.(4)The soil capillary water holding capacity of each stand was between 543.80～645.71 t/hm², and the saturated water holding capacity was between 562.87～694.78 t/hm².(5)The European-style closeness decreased in the order:willow mixed forest(0.805 6)＞salix forest(0.387 7)＞elm forest(0.374 7)＞poplar forest(0.357 2)＞sylvestris pine forest(0.163 2).The greater the European-style closeness, the stronger the water-holding capacity of the stand.Among the five forest types, the water-holding capacity of the mixed willow forest was the strongest, and that of the sylvestris forest was the worst.[Conclusion]It is suggested that the proportion of mixed forests should be appropriately increased, and more forest stands should be rationally matched to construct and protect shelterbelts in the construction of artificial shelterbelts in arid and semi-arid areas in the future. [ABSTRACT FROM AUTHOR]

Arid and semi-arid areas are highly productive ecosystems that have a great diversity of species, among which grasses stand out. These species have ecological, environmental, and economic importance. The objective was to identify the ecological descriptors of 15 native species of grasses and diversity patterns through multivariate analysis techniques (principal component analysis, PCA, and cluster analysis, CA), in addition to identifying potential distribution areas (current and future) and regions of high and low diversity from 3841 accessions and 21 climatic variables. Among the main results, the extreme values, coefficient of variation, and median for each species could be determined. PCA determined that, with 10 variables, it was possible to explain 54.36% of the variation between the analyzed species. CA resulted in the formation of four statistically significant groups, with specific climatic characteristics. Regarding potential distribution areas and climate change, a reduction in distribution is expected (2050) on most of the current surface, with a possible opportunity zone in the north of the country. Finally, two hotspots (high diversity areas) and four coldspots (low diversity areas) were identified among the analyzed species. These results can be used to create strategies for sustainable use and the conservation of these resources. [ABSTRACT FROM AUTHOR]

The ecological quality of arid and semi-arid regions (ASRs) is fragile, and the evaluation of dynamic changes in the multi-factor, long-time-series ecological quality of these regions can provide a scientific basis for sustainable regional development. Based on the remote sensing ecological index (RSEI) and its derivative indices dedicated to monitoring ecological quality in ASRs, this study proposes a new modified RSEI (nmRSEI) suitable for ASRs. We used the nmRSEI to evaluate the dynamic changes in the ecological quality and analyse the factors driving these changes in the Aibugai River Basin in the middle of the Inner Mongolian Plateau in the arid core of Asia from 1986 to 2022. The results led to the following conclusions: (1) the use of the nmRSEI helps solve the problems related to the original greenness index, i.e. normalised difference vegetation index, which was readily affected by the soil background in areas with low vegetation coverage; (2) the new dryness index can meet the evaluation requirements for the surface dryness degree in >98.65% of the study area; (3) the introduced salinity index showed a significant negative correlation with the nmRSEI; (4) the nmRSEI exhibits a gradual downward trend (Slope = −0.00326/10a); and (5) temperature was the main factor controlling the ecological quality during the research period. The nmRSEI provides a fast and effective new method for regularly monitoring ecological quality in ASRs. In addition, driving factor analysis can provide theoretical support for ecological protection in ASRs and the realisation of the United Nations 2030 Sustainable Development Goals.

Arid and semi-arid areas are highly productive ecosystems that have a great diversity of species, among which grasses stand out. These species have ecological, environmental, and economic importance. The objective was to identify the ecological descriptors of 15 native species of grasses and diversity patterns through multivariate analysis techniques (principal component analysis, PCA, and cluster analysis, CA), in addition to identifying potential distribution areas (current and future) and regions of high and low diversity from 3841 accessions and 21 climatic variables. Among the main results, the extreme values, coefficient of variation, and median for each species could be determined. PCA determined that, with 10 variables, it was possible to explain 54.36% of the variation between the analyzed species. CA resulted in the formation of four statistically significant groups, with specific climatic characteristics. Regarding potential distribution areas and climate change, a reduction in distribution is expected (2050) on most of the current surface, with a possible opportunity zone in the north of the country. Finally, two hotspots (high diversity areas) and four coldspots (low diversity areas) were identified among the analyzed species. These results can be used to create strategies for sustainable use and the conservation of these resources.

Introduction: With global warming, the disaster losses caused by extreme precipitation events are increasing. The poor natural conditions and climate change make the arid and semi-arid mountainous grassland area a sensitive region of climate change. The study on the spatio-temporal variation characteristics of extreme precipitation events in this region is helpful to improve the ability of climate prediction and disaster prevention and reduction in grassland. Methods: Based on the daily precipitation data of four meteorological monitoring stations in the Yinshanbeilu from 1970 to 2020, the trend analysis, M-K test and wavelet analysis were used to select seven typical extreme precipitation indicators to analyze the temporal and spatial characteristics of extreme precipitation. Results and Discussion: The results showed that the precipitation in the Yinshanbeilu increased in the past 51a, and the number of heavy rain days increased significantly. The significance test of CDD and CWD showed that the number of continuous dry days and continuous wet days decreased abruptly. The spatial analysis showed that the high value areas of R95p, R95d and PRCRTOT were all located in Siziwang Banner, and it could be concluded that the extreme precipitation risk was the highest in Siziwang Banner, while the low value areas of SDII, Rx1day, R95p and PRCRTOT were all located in Sonid Right Banner, which could be inferred that the Sonid Right Banner was relatively dry. The first main cycle of the seven indexes of extreme precipitation almost runs through the whole time series, and the starting point of the minimum main cycle changes inconsistent. In addition to the number of consecutive dry days, the other indices have a good correlation with annual precipitation, flood season and monthly precipitation from June to September, and July is the peak period of extreme precipitation events. [ABSTRACT FROM AUTHOR]

For thousands of years, date fruit (Phoenix dactylifera L.) has been a popular diet in arid and semi‐arid locations. It has religious importance for Muslims and is especially important during the holy month of Ramadan. The global output of date fruits has been continuously expanding, with Arab nations accounting for a sizable portion. The emphasis of this research is on two popular semi‐dry Algerian date fruit types, Deglet Noor and Arechti, which are grown in the Ziban region. These fruits' physical parameters, such as size, sphericity, surface area, volumes, and density, were determined. The goal of this study was to create a mass model based on these physical attributes to help in the grading and sorting of date fruits. Fruit mass was shown to be closely connected to linear dimensions, arithmetic and geometric mean diameters, surface area, and volumes. Correlations between mass and physical attributes were established using a variety of mathematical models, including linear, quadratic, S‐curve, and power models. The results demonstrated the applicability of specific factors for mass modeling, offering useful insights for the development of system sizing and conservation. With good correlation, multivariate data analysis was employed to correctly estimate the mass of both kinds. This research advances our understanding of the physical features of Algerian date fruits and their connection to mass, allowing for better handling, sorting, and packing processes in the worldwide date market. [ABSTRACT FROM AUTHOR]

Flood and drought are natural phenomena whose probability of occurrence increases with changing weather conditions. Climate change has affected the hydrologic cycle's parameters and led to changes in temperature and precipitation pattern, which may increase the probability of occurrence of floods and droughts. Arid and semi‐arid areas are subject to extreme weather conditions and water resources scarcity. This study aims to assess drought and flood in Syria using remote sensing data. Monthly precipitation data have been collected from 10 land stations in the western part of Syria for the period (1991–2009) and satellite images for monthly precipitation from 1983 to 2020 were collected. The land stations data were used to correct the satellite images and correction equation was developed for each station. Standardized Precipitation Index (SPI) is used for analysis of drought and flood. Also, the main parameters for drought and flood, severity, intensity, duration, and the average return time were estimated. The results showed extreme flood events were recorded in 1988, 2002, 2012, and 2019 and extreme drought events were recorded in 1990, 2014, and 2016. The highest severity of drought and flood were recorded in 2014 and 1988 respectively. However, the highest intensity of droughts and floods was recorded in 2016 and 1988, respectively. If land station data are unavailable, as in the case of Syria owing to the protracted war, satellite images may be a useful source of data for drought and flood analysis after correction. This methodology can help in drought/flood analysis and estimate severity, intensity, duration, and the average return time of flood and drought in other locations of the world. The results proved that SPI is a useful tool to predict the time of occurrence of both flood and drought that could help decision‐makers for putting efficient plans for flood and drought risk management that could mitigate the impacts of such risks. [ABSTRACT FROM AUTHOR]

In the Horqin Sandy Land, the dynamics of the soil-plant-atmosphere-water system and changes in plant water availability significantly impact water resources management and vegetation restoration. This study determined the hydrogen and oxygen isotopic compositions (δD and δ18O) of precipitation, plant water, soil water, and groundwater as well as carbon isotopes of plant leaves during the growing season and different precipitation events (8.9 mm, 18.1 mm, and 28.3 mm) in 2020. Target areas included a semimobile dune with Artemisia halodendron communities (SMAH), a meadow corn field (MCF), and a meadow wetland dominated by Phragmites australis (MPA). The water uptake patterns of the three typical plants were determined using the Iso-Source model. The results showed significant differences in the seasonal variations of δD and δ18O in precipitation, plant water, soil water, and groundwater among SMAH, MCF, and MPA throughout the water cycle, which was attributed to the different origins, distribution, and evaporation mechanisms of water. The influence of precipitation on soil water transport processes varied with the change and transformation of rainfall intensity and ecosystem type. Water conditions and root distribution determined seasonal water use patterns of three plants. The water use efficiency (WUE) of the three typical plants followed the order: corn > Phragmites australis > Artemisia halodendron. And their seasonal WUE were not only consistent with the contribution rate of deep soil water, but also affected by the water use strategies adopted. However, the response of their WUE to rainfall pulses was not significant on the whole. Rainfall intensity, pre-rain mass soil moisture content characteristics and vegetation characteristics are important factors affecting the contribution distribution of different water sources to plants under rainfall events. Artemisia halodendron displays ecological plasticity against seasonal water deficit, facilitating its extensive colonization in dune ecosystem and further promoting the process of dune fixation. The distribution pattern of vegetation water use in the meadow ecosystem is not very ideal at present, and water-carbon processes would gradually become imbalanced in the long run. The research results will provide a reference for sustainable water resource utilization in semi-arid areas through ecohydrological processes.

Abstract Flood and drought are natural phenomena whose probability of occurrence increases with changing weather conditions. Climate change has affected the hydrologic cycle's parameters and led to changes in temperature and precipitation pattern, which may increase the probability of occurrence of floods and droughts. Arid and semi‐arid areas are subject to extreme weather conditions and water resources scarcity. This study aims to assess drought and flood in Syria using remote sensing data. Monthly precipitation data have been collected from 10 land stations in the western part of Syria for the period (1991–2009) and satellite images for monthly precipitation from 1983 to 2020 were collected. The land stations data were used to correct the satellite images and correction equation was developed for each station. Standardized Precipitation Index (SPI) is used for analysis of drought and flood. Also, the main parameters for drought and flood, severity, intensity, duration, and the average return time were estimated. The results showed extreme flood events were recorded in 1988, 2002, 2012, and 2019 and extreme drought events were recorded in 1990, 2014, and 2016. The highest severity of drought and flood were recorded in 2014 and 1988 respectively. However, the highest intensity of droughts and floods was recorded in 2016 and 1988, respectively. If land station data are unavailable, as in the case of Syria owing to the protracted war, satellite images may be a useful source of data for drought and flood analysis after correction. This methodology can help in drought/flood analysis and estimate severity, intensity, duration, and the average return time of flood and drought in other locations of the world. The results proved that SPI is a useful tool to predict the time of occurrence of both flood and drought that could help decision‐makers for putting efficient plans for flood and drought risk management that could mitigate the impacts of such risks.

Proper management and planning of water resources in their operation, distribution, and revitalization play an important role in sustainable development. This issue is of much higher importance in countries located in the arid and semi-arid regions of the world, such as Iran. Because it is inevitable to return and use indigenous technologies and knowledge and update them alongside modern technologies to achieve sustainable development, this research utilizes an extensive study of literature from internal and external sources and exploratory factor analysis to identify and assess the most important criteria or applicable factors of indigenous knowledge relevant to water resources planning and management in Yazd Province. Due to the high importance of the issue, attempts were made to use experienced and relevant faculty members from certain universities, as well as experts and specialists from all relevant organizations in Yazd Province. The results showed that six criteria—protection and stability, integrated management, holistic (comprehensive) approach, cost-effectiveness, compatibility, and dynamism—are found to be more important than others for the area. In the second step of this research, by means of BWM and creating a linear programming model, six principal factors were weighted, and their optimal weights were obtained. The integrated management criterion has the highest weight (0.413), and the holistic approach criterion has the lowest weight (0.048). Moreover, the protection and stability criteria and the cost-effectiveness criteria jointly rank second with a weight of 0.168, and the criteria of compatibility (0.119) and dynamism (0.084), respectively, rank third and fourth.

Introduction Soil classification is the systematic categorization of soils based on distinguishing soil characteristics, aiding in the comprehension of soil properties through soil surveys, and establishing suitable strategies for effective soil utilization and management. One of the main reasons for creating soil classification systems is to identify the differences in important soil characteristics for management purposes. Globally, Soil Taxonomy (ST) and the World Reference Base for soil resources (WRB) are widely used for soil classification. However, these two classification systems have varying criteria which can pose difficulties when exchanging classification results. After years of intensive worldwide testing and data collection, new versions of the ST and WRB systems have been released. In its current state, ST has a strong hierarchy with six categorical levels: order, suborder, great group, subgroup, family, and series (Soil Survey Staff, 2022), while the WRB has a flat hierarchy with only two categorical levels: reference soil groups and soil units (IUSS Working Group WRB, 2022). Several scientists have endeavored to evaluate the merits and demerits of these soil classification systems and offer recommendations for their enhancement. The arid and semi-arid regions located in the western and southwestern parts of Kohgiluyeh and Boyerahmad Province, distinguished by their considerable diversity in parent materials, topography, climate, and land use, present an excellent opportunity for scrutinizing and contrasting the effectiveness of soil classification systems. Remarkably, no prior research has delved into this subject in this specific geographical area. Consequently, this research aims to compare the effectiveness of the ST and WRB systems in characterizing soil attributes. Furthermore, it seeks to analyze the alterations that these two systems have undergone during an eight-year period, spanning from 2014 to 2022. Materials and Methods This study was conducted in the western and southwestern regions of Kohgiluyeh and Boyerahmad Province, specifically in the divisions of Gachsaran, Basht, Choram and Kohgiluyeh. A total of 26 soil profiles were excavated, described, and sampled based on aerial photos, satellite images, topographical and geological maps, as well as field observations. These profiles were selected following the soil description guide provided by the Department of Soil Conservation of the US Department of Agriculture. Subsequently, after reviewing the preliminary results and aligning with the research objectives, 12 representative soil profiles were chosen for further analysis. Soil samples were collected from all genetic horizons and transferred to the laboratory. After air-drying, the samples were passed through a two-millimeter sieve and the routine physical and chemical analyses were conducted, including soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon, cation exchange capacity (CEC), and gypsum analyses. For mineralogical studies, soil clay minerals were separated and identified using standard methods. Additionally, soil thin sections were prepared from intact soil samples of selected soil horizons and examined under a polarizing microscope. Finally, the soil profiles were classified based on the criteria outlined in Soil Taxonomy (2022) and WRB (2022). Results and Discussion Soil Taxonomy and WRB, as the two most popular classification systems, aim to encompass as manysoil characteristics as possible. According to the ST classification, the soils were classified into four orders: Entisols, Inceptisols, Alfisols, and Mollisols. In the WRB system, they were grouped into seven reference soil groups: Regosols, Flovisols, Luvisols, Cambisols, Kastanosems, Gypsysols and Glysols. The results revealed that WRB was significantly more effective in describing the characteristics of the studied soils. One of the key advantages of this two-level system is its flexibility, allowing for the inclusion of additional principal and supplementary qualifiers to cover all essential soil characteristics. Moreover, in many cases, WRB exhibits better prioritization compared to ST. For example, the presence of gypsic, combic, calcic horizons, as well as fluvic and gley properties, can allocate the soil to the reference groups of Gypsisols, Cambisols, Calsisols, Fluvisols, and Gleysols, respectively. However, a limitation of the WRB system is the absence of mineralogical information in soil classification. Enhancing this classification system's quality and making it more appealing to planners could be achieved by incorporating suitable mineralogical attributes for the reference groups or criteria that express soil fertility conditions with relatively straightforward measurements. In addition, it is proposed to add three subgroups to ST: Gypsic Haplustalfs, Fluventic Gypsiustepts and Cambic Haplustolls. Similarly, following the WRB model, it is recommended to introduce a qualifier in ST to indicate the presence of lithological discontinuity. Regarding the WRB system, suggestions include adding qualifiers such as "Cutanic" to gypsisols with clay films, "hypercalcic" to reference groups of Kastanozems and Luvisols with a calcic horizon comprising more than 50% of calcium carbonate, and "aridic" for better expression of soil characteristics with Aridic-Ustic moisture regimes. Conclusion The results of this research demonstrated that WRB is more effective in describing the conditions and characteristics of the studied soils. The WRB system, through its diverse set of qualifiers, is capable of representing field conditions more efficiently. However, it is suggested that the surveyors have the freedom to select an appropriate qualifier from the list provided by WRB without limitation, which can enhance its success in practical applications. Furthermore, it is recommended that both classification systems be used to categorize soils, not only to evaluate their efficiency for the soils in other regions but also to gain a comprehensive understanding of their suitability for different contexts.

Whether land use activities damage a sustainable human-environment ecosystem is one of the most fundamental questions about coupled humanenvironment systems. Therefore, humanities and naturalists are exploring the integration of human-environmental systems on a common denominator spatial basis using Remote Sensing and Geographic Information Systems. Since the 1960s, various methods and tools have been developed to address numerous spatial problems. Consequently, the term ‘Land Change Science’ was emerged as an interdisciplinary field in the 21st century, examining land dynamics in relation to environmental changes and global climate change. Although the Anatolian Peninsula mostly has a characteristic of arid and semi-arid climate and is heavily affected by land use dynamics, the term Land Change Science was found to be absent in the Turkish literature. This study contributes to the field by examining contemporary literature and filling a gap in the existing knowledge.

Drought is the most important factor limiting the growth and production of wheat in China. Arid and semi-arid regions and high water consumption in the agricultural sector have led to various deficit irrigation strategies. The effect of the hydrological process on yield production has been evaluated in rainfed cultivation of wheat for the three climatic stations of Gansu Province, Yellow River Valley, China. A general framework was provided for rainfed cultivation of wheat in arid and semi-arid regions. Moreover, the best time and amount of complementary irrigation and its effect on increasing yield production have been evaluated using grey wolf optimization algorithm. The results showed that rainfed cultivation of wheat in a humid regime could be suggested without complementary irrigation. Conducting two complementary irrigations in semi-humid regime can increase the final yield of wheat by more than 150 kg/ha. The maximum yields in sustainable management were obtained 4,844, 4,510, and 4,408 kg/ha for Longnan, Tianshui, and Dingxi, respectively. HIGHLIGHTS This paper focuses on the modeling of the soil, water, and crop system with more details to improve the applicability.; The proposed method is an optimal policy by applying rainfed management and complementary irrigation.;

Rapid urbanization threatens the ecological environment and quality of life by significantly altering land use and land cover (LULC) and heat distribution. One of the most significant environmental consequences of urbanization is the urban heat island effect (UHI). This study investigated the spatiotemporal characteristics of the SUHI and its relationship with land use types from 2000 to 2020 in Urumqi City, located in an arid and semi-arid region of northwestern China. Additionally, the ordinary least squares (OLS) and geographically weighted regression (GWR) models were used to quantify the relationship between the land surface temperature (LST) and influencing factors. The results showed that the area of the lower surface temperature classes has decreased significantly. In comparison, the area of the higher surface temperature classes has experienced a steady rise over the last two decades. From 2000 to 2020, the share of the area occupied by the temperature range <30 °C decreased by 67.09%. In addition, the LST varied significantly from one category of land use to another. The average LST of built-up land and unused land was higher than the average LST of other land use types in all years, while the average LST of grassland, forest land, and water bodies was significantly lower. Finally, the results of the GWR model showed that R2 and adjusted R2 of the GWR were 0.75 and 0.73, obviously larger than the 0.58 of the OLS models. The GWR model's higher R2 and adjusted R2 compared to the OLS model indicates that the relationship between LST and the influencing factors underlying the model may exhibit spatial non-stationarity, and the GWR model performs better than the OLS model. The results of both OLS and GWR models show that the normalized difference vegetation index (NDVI) and slope were negatively correlated with LST, while the urban index (UI) and normalized difference built-up index (NDBI) were positively correlated with LST. The findings of the study indicate that increasing green spaces and limiting the unplanned expansion of urban areas are effective measures to mitigate the UHIs in the study area. The results of the study may provide valuable insights into the spatiotemporal characteristics of the UHI and its drivers. Understanding the spatiotemporal characteristics of the UHI can help urban planners, policymakers, and scientists develop more effective urban cooling strategies and improve the urban thermal environment. [ABSTRACT FROM AUTHOR]

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In arid and semi-arid regions, rainfall takes on a critical significance to both agricultural and engineering construction activities, and the transport process and driving mechanism of soil water under rainfall conditions are in need of further investigation. To clarify the variations in soil moisture, temperature, and liquid and vapor flux under various rainfall scenarios, the Mu Us Sandy Land was selected as the study region, and a water–vapor–heat transport model was established using the Hydrus-1D software with in situ observed soil and meteorological data. The simulated results were in good agreement with the measured data during both the calibration and validation periods, suggesting that the model was accurate and applicable to the study region. The variations in the selected dry and rainy periods proved the significant effect of rainfall events on soil matric potential, temperature, and driving forces. When rainfall occurred, the hydraulic conductivity for liquid water rose by three to five orders of magnitude, driving the liquid water flow downward. In contrast, the vapor flux played a vital role in soil water movement, accounting for about 15% of the total water flux in the shallow layer when the soil was dry, while it became non-significant during rainy periods due to the reduction in hydraulic conductivity for vapor and the temperature gradient. These results clarified the mechanisms of soil liquid water and vapor movement in arid areas, which could provide scientific support for future studies on vegetation restoration and ecosystem sustainability in ecologically fragile areas. [ABSTRACT FROM AUTHOR]

Despite water shortages and infrequent rainfall in arid and semi-arid areas, their recent floods show that flooding tends to be more severe and life-threatening. However, flooding is a poorly understood natural hazard in arid and semi-arid areas and its management needs to address a set of challenges, some of which are unique to these zones. Hence, it is of great demand to develop a comprehensive understanding of Flood Risk Management (FRM) difficulties and needs that are significant in these regions. This review paper aimed to understand the current state of FRM in arid and semi-arid areas and to explore challenges existing in FRM of these zones, based on the authors' experiences from practice-based research. The study identified four main classes of challenges: (i) regional features and flood characteristics, (ii) operational challenges, (iii) technical challenges, and (iv) management/organizational challenges. It was then concluded that these FRM challenges are multidimensional and coupled together. After discussing the challenges, the study addressed requirements and provided an outlook on solutions, further improvements, and possibilities for FRM in these regions. [ABSTRACT FROM AUTHOR]

Introduction Soil classification is the systematic categorization of soils based on distinguishing soil characteristics, aiding in the comprehension of soil properties through soil surveys, and establishing suitable strategies for effective soil utilization and management. One of the main reasons for creating soil classification systems is to identify the differences in important soil characteristics for management purposes. Globally, Soil Taxonomy (ST) and the World Reference Base for soil resources (WRB) are widely used for soil classification. However, these two classification systems have varying criteria which can pose difficulties when exchanging classification results. After years of intensive worldwide testing and data collection, new versions of the ST and WRB systems have been released. In its current state, ST has a strong hierarchy with six categorical levels: order, suborder, great group, subgroup, family, and series (Soil Survey Staff, 2022), while the WRB has a flat hierarchy with only two categorical levels: reference soil groups and soil units (IUSS Working Group WRB, 2022). Several scientists have endeavored to evaluate the merits and demerits of these soil classification systems and offer recommendations for their enhancement. The arid and semi-arid regions located in the western and southwestern parts of Kohgiluyeh and Boyerahmad Province, distinguished by their considerable diversity in parent materials, topography, climate, and land use, present an excellent opportunity for scrutinizing and contrasting the effectiveness of soil classification systems. Remarkably, no prior research has delved into this subject in this specific geographical area. Consequently, this research aims to compare the effectiveness of the ST and WRB systems in characterizing soil attributes. Furthermore, it seeks to analyze the alterations that these two systems have undergone during an eightyear period, spanning from 2014 to 2022. Materials and Methods This study was conducted in the western and southwestern regions of Kohgiluyeh and Boyerahmad Province, specifically in the divisions of Gachsaran, Basht, Choram and Kohgiluyeh. A total of 26 soil profiles were excavated, described, and sampled based on aerial photos, satellite images, topographical and geological maps, as well as field observations. These profiles were selected following the soil description guide provided by the Department of Soil Conservation of the US Department of Agriculture. Subsequently, after reviewing the preliminary results and aligning with the research objectives, 12 representative soil profiles were chosen for further analysis. Soil samples were collected from all genetic horizons and transferred to the laboratory. After air-drying, the samples were passed through a two-millimeter sieve and the routine physical and chemical analyses were conducted, including soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon, cation exchange capacity (CEC), and gypsum analyses. For mineralogical studies, soil clay minerals were separated and identified using standard methods. Additionally, soil thin sections were prepared from intact soil samples of selected soil horizons and examined under a polarizing microscope. Finally, the soil profiles were classified based on the criteria outlined in Soil Taxonomy (2022) and WRB (2022). Results and Discussion Soil Taxonomy and WRB, as the two most popular classification systems, aim to encompass as many soil characteristics as possible. According to the ST classification, the soils were classified into four orders: Entisols, Inceptisols, Alfisols, and Mollisols. In the WRB system, they were grouped into seven reference soil groups: Regosols, Flovisols, Luvisols, Cambisols, Kastanosems, Gypsysols and Glysols. The results revealed that WRB was significantly more effective in describing the characteristics of the studied soils. One of the key advantages of this two-level system is its flexibility, allowing for the inclusion of additional principal and supplementary qualifiers to cover all essential soil characteristics. Moreover, in many cases, WRB exhibits better prioritization compared to ST. For example, the presence of gypsic, combic, calcic horizons, as well as fluvic and gley properties, can allocate the soil to the reference groups of Gypsisols, Cambisols, Calsisols, Fluvisols, and Gleysols, respectively. However, a limitation of the WRB system is the absence of mineralogical information in soil classification. Enhancing this classification system's quality and making it more appealing to planners could be achieved by incorporating suitable mineralogical attributes for the reference groups or criteria that express soil fertility conditions with relatively straightforward measurements. In addition, it is proposed to add three subgroups to ST: Gypsic Haplustalfs, Fluventic Gypsiustepts and Cambic Haplustolls. Similarly, following the WRB model, it is recommended to introduce a qualifier in ST to indicate the presence of lithological discontinuity. Regarding the WRB system, suggestions include adding qualifiers such as "Cutanic" to gypsisols with clay films, "hypercalcic" to reference groups of Kastanozems and Luvisols with a calcic horizon comprising more than 50% of calcium carbonate, and "aridic" for better expression of soil characteristics with Aridic-Ustic moisture regimes. Conclusion The results of this research demonstrated that WRB is more effective in describing the conditions and characteristics of the studied soils. The WRB system, through its diverse set of qualifiers, is capable of representing field conditions more efficiently. However, it is suggested that the surveyors have the freedom to select an appropriate qualifier from the list provided by WRB without limitation, which can enhance its success in practical applications. Furthermore, it is recommended that both classification systems be used to categorize soils, not only to evaluate their efficiency for the soils in other regions but also to gain a comprehensive understanding of their suitability for different contexts. [ABSTRACT FROM AUTHOR]

This study introduces the foundational principles behind the water footprint in water and food security for evaluating the managerial strategies of agricultural water management in arid areas. The role of green, grey, blue and white water footprints in yield production has been critically investigated to analyze the climate and economic risks. Therefore, a nonlinear hydro-economic framework, which integrates soil water content, food production and economics has been used for the semi-arid regions of China. Non-dimensional form of net benefit per drop was formulated to analyze the uncertainty of economic parameters. Root zone moisture was simulated to estimate crop yield, transpiration, evaporation, water required for irrigation and increase water quality. Five plants of potato, onion, tomato, eggplant and carrot were selected due to similarity in the plant growth season and market criteria. The results showed that the average effective rainfall contributed less than 15% to food production. The impact of the risk of economic fluctuations in achieving the expected net profit has been more than water. HIGHLIGHTS The impact of the water footprint on food security was considered to improve agricultural water management in arid areas.; A hydro-economic framework, which integrates soil water content, food production and economics has been used.; Non-dimensional form of net benefit per drop was formulated to analyze the uncertainty of economic parameters.;

Since the beginning of the 21st century, vegetation greening in China has continuously increased and ranks among the top globally, especially in the western and northern regions of the country. This study analyzed the characteristics of the greening rates of different vegetation types in China's arid and semi-arid regions in the northwest, using satellite-derived Normalized Difference Vegetation Index (NDVI) data from 2002 to 2021. Furthermore, the study explored the response of greening rates to climate change and its temporal effect. The study found that in the past two decades, the vegetation greening rates in the southeastern region of China's arid and semi-arid areas are higher than that in the northwest. Vegetation change in the arid and semi-arid regions of China exhibits significant spatial heterogeneity in response to climate change. The vegetation greening rates in the southeast of the study area increases with precipitation, while in the northwest, it is promoted by daytime temperature and day-night temperature difference. The greening rates of cultivated vegetation, grassland, and meadow thicket is mainly affected by precipitation, while the greening rates of alpine grassland is mainly affected by day-night temperature difference. In addition, the response of vegetation greening rates to climate in China's arid and semi-arid regions has significant time lag and cumulative effects. Climate changes before the growing season (February to May) can also affect vegetation greening rates during the growing season (June to September). The cumulative climate changes over four months have a greater impact on vegetation greening rate than those over two months. Our study quantified the contribution of climate change to the greening rates of different vegetation types, which can provide references for predicting the dynamic changes of vegetation under future climate change.

Water shortage is a concern in arid and semi-arid regions across the globe due to their lack of precipitation and unpredictable rainfall patterns. In the past few decades, many frameworks, each with their own criteria, have been used to identify and rank sites for rainwater harvesting (RWH), a process which is critical for the improvement and maintenance of water resources, particularly in arid and semi-arid regions. This study reviews the present state of the art in rainwater harvesting site selection for such regions and identifies areas for additional research. The results of a systematic review performed based on two major databases of engineering research, Scopus and Engineering Village, are presented. Sixty-eight relevant studies were found and critically analysed to identify patterns and unique features in the frameworks used. The results of this study show that 41% of the frameworks consider both biophysical and socioeconomic criteria, whereas the remaining 59% of the frameworks depend on biophysical criteria alone. The importance of each criterion is encapsulated through a suitability score, with 21% of the frameworks using a binary (0 or 1) indicator of whether the site matches a criterion or not and the other frameworks using graded scales of differing granularities, with 52% using a low-resolution scale of 1 to 3, 4, or 5, 7% using a medium-resolution scale of 1 to 10, and a further 7% using a high-resolution scale of 1 to 100. The remaining 13% of the frameworks did not specify the scale used. Importantly, this paper concludes that all existing frameworks for selecting RWH sites are solely based on biophysical and/or socioeconomic criteria; ecological impacts, the consideration of which is vital for building RWH systems sustainably, are currently ignored. [ABSTRACT FROM AUTHOR]

With the increased availability of global datasets and the consequent proliferation of national and global studies, regional analyses have taken a back seat. However, regional analyses with observed data form the backbone of localised planning to counter climate change and validation of global data. In this context, the spatiotemporal changes in rainfall over different time scales covering the sub-tropical arid and semi-arid regions over the Thar Desert area are studied. The station rainfall data of 137 stations (1973–2008) has been analysed using annual, seasonal, monthly time-series and rainfall indices ('Expert Team on Climate Change Detection and Indices' – ETCCDI). The Mann–Kendall and modified Mann–Kendall tests were used to compute the trends of the rainfall attributes. Application of ETCCDI on station data and at rarely touched Thar Desert area is the novelty of this study. Overall, rainfall shows a decreasing trend. Annual rainfall has decreased by about 16.8% over the study area, with the number of rainy days decreasing by only 2% (1973–2008). An important finding is a potential smoothing of the temporal distribution of rainfall with an overall decrease in monsoon rainfall in 96 (70%) stations and an increase in pre-monsoon rainfall in 104 (76%) stations. This finding is corroborated by a decrease in the continuous dry days in 115 (84%) stations and in the intensity of rainfall in 103 (75%) stations. In most of the cases, it has been found that the trends are non-significant in the western arid part of the Aravalli Range, while they are significant in the eastern part. [ABSTRACT FROM AUTHOR]

Global warming and human activities are complicating the spatial and temporal relationships between basin hydrologic processes and ecosystem quality (EQ), especially in arid and semi-arid regions. Knowledge of the synergy between hydrological processes and ecosystems in arid and semi-arid zones is an effective measure to achieve ecologically sustainable development. In this study, the inland river basin Ulagai River Basin (URB), a typical arid and semi-arid region in Northern China, was used as the study area; based on an improved hydrological model and remote-sensing and in situ measured data, this URB-focused study analyzed the spatial and temporal characteristics of hydrological process factors, such as precipitation, evapotranspiration (ET), surface runoff, lateral flow, groundwater recharge, and EQ and the synergistic relationships between them. It was found that, barring snowmelt, the hydrological process factors such as precipitation, ET, surface runoff, lateral flow, and groundwater recharge had a rising trend in the URB, since the 20th century. The rate of change was higher in the downstream areas when compared with what it was in the upstream and midstream areas. The multi-year average of EQ in the basin is 53.66, which is at a medium level and has an overall improving trend, accounting for 95.14% of the total area, mainly in the upstream, downstream southern, and downstream northern areas of the basin. The change in relationship between the hydrological process factors and EQ was found to have a highly synergistic effect. Temporally, EQ was consistent with the interannual trends of precipitation, surface runoff, lateral flow, and groundwater recharge. The correlation between the hydrological process factors and EQ was found to be higher than 0.7 during the study period. Spatially, the hydrological process factors had a synergistic relationship with EQ from strong to weak upstream, midstream, and downstream, respectively. In addition, ecosystem improvements were accelerated by government initiatives such as the policy of Returning Grazing Land to Grassland Project, which has played an important role in promoting soil and water conservation and EQ. This study provides theoretical support for understanding the relationship between hydrological processes and ecological evolution in arid and semi-arid regions, and it also provides new ideas for related research. [ABSTRACT FROM AUTHOR]

The study investigated the effect of colchicine (C) on seeds germination, as well as morph physiological traits of wheat, where dry wheat seeds were treated with colchicine at concentrations of (C) were (0.02, 0.04, 0.06, and 0.08 %) compared to soaking in distilled water (control). The variance analysis results of laboratory germination experiments as well as in field experiments under rain-fed conditions showed that there were significant differences (P < 0.05) in the mean of most of the studied quantitative traits: germination quality such as germination force (%), germination energy (%), and laboratory germination (%). Leaf area (cm2 ), root spread, stem diameter (cm), as well as wet and dry weight under the influence of the different concentrations of colchicine. Where the results showed that when used wheat seeds which pre-soaked with colchicine solution at a concentration of (0.06) % for 56 hours pre-sowing, led to an obvious significant increase in all studied traits morph physiological properties and seedling vigor when compared to the control (untreated seeds - treated with distilled water only) as well as when compared with other concentrations of colchicine

Ongoing climate change processes and increasing environmental pressure suggest the need to adjust the wine production systems worldwide to the new conditions while reducing their environmental pressure. The grapes' cultivation phase may be influenced by expected changes. It follows that existing grape wine cultivation systems should be analyzed to identify major 'hotspots' and opportunities for change. Several studies have analyzed materials, energy inputs, and related emissions along the grape wine life cycle. However, most research focuses on traditional grape wine growing areas, and no study has yet focused on grape wine grown in unconventional desert areas. The research presented in this paper analyzed the carbon footprint (CF) of grapes grown in the Mediterranean, semi-arid, and arid climatic regions in the state of Israel. It revealed that, on average, a ton of grapes generates 342 kg CO2 eq from the cradle to the farm gate. The product was analyzed using a life-cycle approach, with the aim of studying the CF of each phase according. Most emissions were found to be related to the use of fertilizers (37%), fuel for transportation and mechanization (19%), and water supply (17%). The CF of grapes in the arid region was found to be the highest at 361 kg CO2 eq compared to 317 kg CO2 eq in the semi-arid region and 346 kg CO2 eq in the Mediterranean region. The analysis emphasizes the arid and semi-arid potential to reduce its CF by implementing farm management practices, including the choice of grape varieties, changing vineyard infrastructure, fertilizers, water management, and more. As presented here, understanding cropping systems in these regions can promote a better adaptation of the cropping systems to the changing conditions around the world. [ABSTRACT FROM AUTHOR]

Today, the increase of the world's population and climate change has resulted in the reduction of fresh water resources and the increase of arid and semi-arid areas, and thus, it is necessary to find a new solution to increase the production of food resources. Aquaculture is one of the sources of food production, which can play a key role in fighting poverty and hunger. Sustainable aquaculture is strongly dependent on water quantity and quality, and also, optimal fish production can be determined by the physical, chemical and biological quality of water. Due to the current restrictions and the global increase in demand for aquatic products, unconventional waters (UWs) have been used in aquaculture. UWs include: recycled water, sewage, saline water, agricultural drains and water resulting from the process of sweetening and desalination of salty water. Today, these water resources have been used to grow all kinds of aquatic animals to provide food and protein. Considering the limited water resources in the world, the use of UWs is very effective and efficient in managing drought, and is considered as one of the ways to develop food production for humans. Due to its importance in areas facing water scarcity, the use of unconventional water resources (UWRs) to supplement or replace the use of conventional fresh water sources has been considered. In this review study, the importance of UWs and their sources, aquaculture products and aquatics that can be cultivated with the help of UWs are discussed. [ABSTRACT FROM AUTHOR]

An assessment of the total hydrologic response of arid and semi-arid river basins to various scenarios of climate change by considering evapotranspiration, streamflow, and snowmelt is essential for sustainable management of water resources. The Diyala River Basin in Iraq has been chosen as a typical case study of dozens of river basins in arid and semi-arid regions. Here, the Long Ashton Research Station-Weather Generator (LARS-WG), the Soil and Water Assessment Tool (SWAT), and the SWAT Calibration and Uncertainty Program (CUP) were used to evaluate the total response by considering three Representative Concentration Pathways (RCPs); RCPs 2.6, 4.5, and 8.5 over three periods, 2021–2040, 2041–2061, and 2061–2080. The results indicate that by the year 2080, the basin will experience a temperature increase by 6.6, 10.1, and 16.6% for RCP 2.6, RCP 4.5, and RCP 8.5, respectively. The corresponding reduction in precipitation will be 3.2, 6.4, and 8.7%, resulting in 38.8, 47.9, and 52.8% fall in streamflow for RCPs 2.6, 4.5, and 8.5, respectively. Due to the increase in temperature, an earlier and less contribution of snowmelt is expected in the projected streamflow. Our findings provide a useful reference and a guide to decision makers for developing adaption plans to sustainably manage water resources in the Diyala River Basin and other similar basins in arid and semi-arid regions. HIGHLIGHTS The study provides valuable information on possible future changes in streamflow under a changing climate.; LARS-WG, SWAT, SWAT-CUP, and three RCP scenarios to predict the hydrologic response of a river basin are used.; Precipitation is predicted to decrease, resulting in a reduction in streamflow.; This study supports the sustainable use of water resources in a changing climate.; This study serves the development of adaptation plans to climate change and its effects.;

• The model is optimized for global GPP and ET estimation with enhanced accuracy. • NIRv improves GPP precision by coupling with ET through f APAR. • ET simulations outperform foundational and remote sensing models. • The model shows higher correlation and lower RMSE for GPP estimation using NIRv. In arid and semi-arid regions, accurate estimates of global primary productivity (GPP) and evapotranspiration (ET) are critical for understanding and managing water and carbon cycling in these fragile ecosystems. In this study, an improved ET-photosynthesis model (PT-JPL-GPP) was used to optimize GPP and ET estimates in these ecosystems by introducing the near infrared reflectance index (NIRv). NIRv, an indicator of the light use efficiency of vegetation, was integrated into the PT-JPL model. Compared to the original PT-JPL and existing remote sensing models, this PT-JPL-GPP model displayed a higher correlation (R2 = 0.73) and lower BIAS (−19.57 %) for GPP estimation. ET estimates were also noticeably improved, the R2 increased by 0.03(SN-Dhr) to 0.16(US-SRC), and the Root Mean Square Error (RMSE) reduced by 0.57 mm/month (SN-Dhr) to 4.64 mm/month (US-SRC). Particularly at the GRA site, the R2 was increased from 0.63 to 0.74, and the RMSE and bias was decreased by 1.25 mm/month and 10.51 %, respectively. The PT-JPL-GPP model was comparable with GLEAM, VPM, MOD17, MOD16, and PML-V2 models. The PT-JPL-GPP model exhibits a lower root mean square error and higher correlation for estimating GPP, compared to the VPM, MOD17, and PML-V2 models. The PT-JPL-GPP model outperformed PT-JPL, MOD16 models for estimating ET, but was slightly poorer than GLEAM and PML-V2 models. Our results highlight the merits of NIRv for improving GPP and ET estimates. [ABSTRACT FROM AUTHOR]

The ecological quality of arid and semi-arid regions (ASRs) is fragile, and the evaluation of dynamic changes in the multi-factor, long-time-series ecological quality of these regions can provide a scientific basis for sustainable regional development. Based on the remote sensing ecological index (RSEI) and its derivative indices dedicated to monitoring ecological quality in ASRs, this study proposes a new modified RSEI (nmRSEI) suitable for ASRs. We used the nmRSEI to evaluate the dynamic changes in the ecological quality and analyse the factors driving these changes in the Aibugai River Basin in the middle of the Inner Mongolian Plateau in the arid core of Asia from 1986 to 2022. The results led to the following conclusions: (1) the use of the nmRSEI helps solve the problems related to the original greenness index, i.e. normalised difference vegetation index, which was readily affected by the soil background in areas with low vegetation coverage; (2) the new dryness index can meet the evaluation requirements for the surface dryness degree in >98.65% of the study area; (3) the introduced salinity index showed a significant negative correlation with the nmRSEI; (4) the nmRSEI exhibits a gradual downward trend (Slope = −0.00326/10a); and (5) temperature was the main factor controlling the ecological quality during the research period. The nmRSEI provides a fast and effective new method for regularly monitoring ecological quality in ASRs. In addition, driving factor analysis can provide theoretical support for ecological protection in ASRs and the realisation of the United Nations 2030 Sustainable Development Goals. • An improved RSEI applicable to the evaluation of ecological quality in arid and low vegetation cover areas was proposed. • The new greenness index can effectively solve the problem that the old greenness index is affected by the soil background. • The introduced new dryness index is able to meet the surface dryness evaluation requirements for 98.65% of the study area. • The reliability of nmRSEI was evaluated by introducing NPP, CLCD and EI. [ABSTRACT FROM AUTHOR]

Rapid urbanization threatens the ecological environment and quality of life by significantly altering land use and land cover (LULC) and heat distribution. One of the most significant environmental consequences of urbanization is the urban heat island effect (UHI). This study investigated the spatiotemporal characteristics of the SUHI and its relationship with land use types from 2000 to 2020 in Urumqi City, located in an arid and semi-arid region of northwestern China. Additionally, the ordinary least squares (OLS) and geographically weighted regression (GWR) models were used to quantify the relationship between the land surface temperature (LST) and influencing factors. The results showed that the area of the lower surface temperature classes has decreased significantly. In comparison, the area of the higher surface temperature classes has experienced a steady rise over the last two decades. From 2000 to 2020, the share of the area occupied by the temperature range 2 and adjusted R2 of the GWR were 0.75 and 0.73, obviously larger than the 0.58 of the OLS models. The GWR model’s higher R2 and adjusted R2 compared to the OLS model indicates that the relationship between LST and the influencing factors underlying the model may exhibit spatial non-stationarity, and the GWR model performs better than the OLS model. The results of both OLS and GWR models show that the normalized difference vegetation index (NDVI) and slope were negatively correlated with LST, while the urban index (UI) and normalized difference built-up index (NDBI) were positively correlated with LST. The findings of the study indicate that increasing green spaces and limiting the unplanned expansion of urban areas are effective measures to mitigate the UHIs in the study area. The results of the study may provide valuable insights into the spatiotemporal characteristics of the UHI and its drivers. Understanding the spatiotemporal characteristics of the UHI can help urban planners, policymakers, and scientists develop more effective urban cooling strategies and improve the urban thermal environment.

In arid and semi-arid regions, rainfall takes on a critical significance to both agricultural and engineering construction activities, and the transport process and driving mechanism of soil water under rainfall conditions are in need of further investigation. To clarify the variations in soil moisture, temperature, and liquid and vapor flux under various rainfall scenarios, the Mu Us Sandy Land was selected as the study region, and a water–vapor–heat transport model was established using the Hydrus-1D software with in situ observed soil and meteorological data. The simulated results were in good agreement with the measured data during both the calibration and validation periods, suggesting that the model was accurate and applicable to the study region. The variations in the selected dry and rainy periods proved the significant effect of rainfall events on soil matric potential, temperature, and driving forces. When rainfall occurred, the hydraulic conductivity for liquid water rose by three to five orders of magnitude, driving the liquid water flow downward. In contrast, the vapor flux played a vital role in soil water movement, accounting for about 15% of the total water flux in the shallow layer when the soil was dry, while it became non-significant during rainy periods due to the reduction in hydraulic conductivity for vapor and the temperature gradient. These results clarified the mechanisms of soil liquid water and vapor movement in arid areas, which could provide scientific support for future studies on vegetation restoration and ecosystem sustainability in ecologically fragile areas.

Qanats in the aquifer of the Tehuacán Valley (Mexico) represent an ancient way of using groundwater that is still practiced today. They are used mainly for agricultural irrigation. However, anthropogenic activities have jeopardized the use of these aquifers. We analyzed 24 qanats in the Tehuacán Valley to assess water quality. Based on 24 physicochemical variables, a water quality index (WQI) was constructed on a zero-to-100 scale, divided into five water quality classes. A decision-tree analysis was applied to identify the parameters with the highest influence on the WQI, considering the water quality classes as categorical responses and the values of physicochemical variables as drivers of these categories. We produced interpolation maps to identify trends. The relationship between the WQI and the normalized difference indices of vegetation and salinity (NDVI and NDSI, respectively) was analyzed using a ternary diagram. WQI scores showed that 12.5% of the qanats have very good quality; 25%, good quality; and the remaining (62.5%) range from moderate to unacceptable quality. The CHAID classification-tree method correctly explained 83.3% of the categories, with sulfates, alkalinity, conductivity, and nitrates as the main parameters that explain water quality. WQI was inversely related to NDVI and NDSI, showing seasonal differences. Interpolation maps suggest a better water quality in the northern zone of the aquifer. [ABSTRACT FROM AUTHOR]

This study examined the influence of water periods on river nitrogen cycling by analysing nitrogen functional genes and bacterial communities in the Qingshui River, an upstream tributary of the Yellow River in China. Nitrate nitrogen predominated as inorganic nitrogen during the low-flow seasons, whereas salinity was highest during the high-flow seasons. Overall, the functional gene abundance increased with decreasing water volume, and nitrogen concentrations were determined by various specific gene groups. The relative abundance of bacteria carrying these genes varied significantly across water periods. The abundance of Pseudomona, Hydrogenophaga (carrying narGHI and nirB genes), and Flavobacterium (carrying nirK, norBC, and nosZ genes) significantly increased during the low-flow seasons. Nitrogen transformation bacteria exhibited both symbiotic and mutualistic relationships. Microbial network nodes and sizes decreased with decreasing water volume, whereas modularity increased. Additionally, the water period affected the functional microbial community structure by influencing specific environmental factors. Among them, SO 4 2- primarily determined the denitrification, dissimilatory nitrate reduction to ammonium, and assimilatory nitrate reduction to ammonium communities, whereas NO 2 were the main driving factors for the nitrogen-fixing and nitrifying communities, respectively. These findings have substantial implications for better understanding the reduction in river nitrogen loads in arid and semi-arid regions during different water periods.- -N and Mg 2+ were the main driving factors for the nitrogen-fixing and nitrifying communities, respectively. These findings have substantial implications for better understanding the reduction in river nitrogen loads in arid and semi-arid regions during different water periods., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Despite water shortages and infrequent rainfall in arid and semi-arid areas, their recent floods show that flooding tends to be more severe and life-threatening. However, flooding is a poorly understood natural hazard in arid and semi-arid areas and its management needs to address a set of challenges, some of which are unique to these zones. Hence, it is of great demand to develop a comprehensive understanding of Flood Risk Management (FRM) difficulties and needs that are significant in these regions. This review paper aimed to understand the current state of FRM in arid and semi-arid areas and to explore challenges existing in FRM of these zones, based on the authors’ experiences from practice-based research. The study identified four main classes of challenges: (i) regional features and flood characteristics, (ii) operational challenges, (iii) technical challenges, and (iv) management/organizational challenges. It was then concluded that these FRM challenges are multidimensional and coupled together. After discussing the challenges, the study addressed requirements and provided an outlook on solutions, further improvements, and possibilities for FRM in these regions.

Water shortage is a concern in arid and semi-arid regions across the globe due to their lack of precipitation and unpredictable rainfall patterns. In the past few decades, many frameworks, each with their own criteria, have been used to identify and rank sites for rainwater harvesting (RWH), a process which is critical for the improvement and maintenance of water resources, particularly in arid and semi-arid regions. This study reviews the present state of the art in rainwater harvesting site selection for such regions and identifies areas for additional research. The results of a systematic review performed based on two major databases of engineering research, Scopus and Engineering Village, are presented. Sixty-eight relevant studies were found and critically analysed to identify patterns and unique features in the frameworks used. The results of this study show that 41% of the frameworks consider both biophysical and socioeconomic criteria, whereas the remaining 59% of the frameworks depend on biophysical criteria alone. The importance of each criterion is encapsulated through a suitability score, with 21% of the frameworks using a binary (0 or 1) indicator of whether the site matches a criterion or not and the other frameworks using graded scales of differing granularities, with 52% using a low-resolution scale of 1 to 3, 4, or 5, 7% using a medium-resolution scale of 1 to 10, and a further 7% using a high-resolution scale of 1 to 100. The remaining 13% of the frameworks did not specify the scale used. Importantly, this paper concludes that all existing frameworks for selecting RWH sites are solely based on biophysical and/or socioeconomic criteria; ecological impacts, the consideration of which is vital for building RWH systems sustainably, are currently ignored.

In the Horqin Sandy Land, the dynamics of the soil-plant-atmosphere-water system and changes in plant water availability significantly impact water resources management and vegetation restoration. This study determined the hydrogen and oxygen isotopic compositions (δD and δ 18 O) of precipitation, plant water, soil water, and groundwater as well as carbon isotopes of plant leaves during the growing season and different precipitation events (8.9 mm, 18.1 mm, and 28.3 mm) in 2020. Target areas included a semimobile dune with Artemisia halodendron communities (SMAH), a meadow corn field (MCF), and a meadow wetland dominated by Phragmites australis (MPA). The water uptake patterns of the three typical plants were determined using the Iso-Source model. The results showed significant differences in the seasonal variations of δD and δ 18 O in precipitation, plant water, soil water, and groundwater among SMAH, MCF, and MPA throughout the water cycle, which was attributed to the different origins, distribution, and evaporation mechanisms of water. The influence of precipitation on soil water transport processes varied with the change and transformation of rainfall intensity and ecosystem type. Water conditions and root distribution determined seasonal water use patterns of three plants. The water use efficiency (WUE) of the three typical plants followed the order: corn > Phragmites australis > Artemisia halodendron. And their seasonal WUE were not only consistent with the contribution rate of deep soil water, but also affected by the water use strategies adopted. However, the response of their WUE to rainfall pulses was not significant on the whole. Rainfall intensity, pre-rain mass soil moisture content characteristics and vegetation characteristics are important factors affecting the contribution distribution of different water sources to plants under rainfall events. Artemisia halodendron displays ecological plasticity against seasonal water deficit, facilitating its extensive colonization in dune ecosystem and further promoting the process of dune fixation. The distribution pattern of vegetation water use in the meadow ecosystem is not very ideal at present, and water-carbon processes would gradually become imbalanced in the long run. The research results will provide a reference for sustainable water resource utilization in semi-arid areas through ecohydrological processes. • The plants water use efficiency (WUE) followed the order: corn > Phragmites australis > Artemisia halodendron. • The response of plant WUE to rainfall pulses was not significant. • The plant species influence leaf stable carbon isotope characteristics. • Water conditions and vegetation characteristics determined the water use patterns of plants. [ABSTRACT FROM AUTHOR]

Global warming and human activities are complicating the spatial and temporal relationships between basin hydrologic processes and ecosystem quality (EQ), especially in arid and semi-arid regions. Knowledge of the synergy between hydrological processes and ecosystems in arid and semi-arid zones is an effective measure to achieve ecologically sustainable development. In this study, the inland river basin Ulagai River Basin (URB), a typical arid and semi-arid region in Northern China, was used as the study area; based on an improved hydrological model and remote-sensing and in situ measured data, this URB-focused study analyzed the spatial and temporal characteristics of hydrological process factors, such as precipitation, evapotranspiration (ET), surface runoff, lateral flow, groundwater recharge, and EQ and the synergistic relationships between them. It was found that, barring snowmelt, the hydrological process factors such as precipitation, ET, surface runoff, lateral flow, and groundwater recharge had a rising trend in the URB, since the 20th century. The rate of change was higher in the downstream areas when compared with what it was in the upstream and midstream areas. The multi-year average of EQ in the basin is 53.66, which is at a medium level and has an overall improving trend, accounting for 95.14% of the total area, mainly in the upstream, downstream southern, and downstream northern areas of the basin. The change in relationship between the hydrological process factors and EQ was found to have a highly synergistic effect. Temporally, EQ was consistent with the interannual trends of precipitation, surface runoff, lateral flow, and groundwater recharge. The correlation between the hydrological process factors and EQ was found to be higher than 0.7 during the study period. Spatially, the hydrological process factors had a synergistic relationship with EQ from strong to weak upstream, midstream, and downstream, respectively. In addition, ecosystem improvements were accelerated by government initiatives such as the policy of Returning Grazing Land to Grassland Project, which has played an important role in promoting soil and water conservation and EQ. This study provides theoretical support for understanding the relationship between hydrological processes and ecological evolution in arid and semi-arid regions, and it also provides new ideas for related research.

Biological soil crust is an important feature of desert ecosystem composition and surface landscape. Determining the role of biological soil crust in the energy flow and logistics cycle in the desert ecosystem is one of the frontier areas of ecological restoration in arid and semi-arid areas. Obtaining biological soil crust information from drone images is an efficient, fast, and low-cost method. However, due to the scattered and uneven growth of biological soil crusts and the complexity of the field environment, it is difficult to accurately extract biological soil crusts. In view of this, this study used the improved UNet++ model to extract biological soil crusts based on UAV image data. Firstly, the optimal Epoch, Backbone, and Loss function are selected and trained based on the network structure of UNet++ model. Then, the improved UNet++ model proposed in this paper, which takes ResNeXt as the Backbone and Soft Cross-Entropy Loss+Dice Loss as the Loss Function, is obtained. Finally, the test results of UNet++, U-Net, LinkNet, FPN, and PSPNet are compared with the improved UNet++ model in this paper. The results showed that the improved UNet++ model had the best segmentation effect, and the precision, recall, F1-Score, and IoU were 0.9788, 0.9501, 0.9495, and 0.9309, respectively. UAV image biological soil crust recognition based on the improved UNet++ model in this paper can obtain high-precision extraction results, provide good data support for studying the development of biological soil crusts in arid areas, and provide a new method for precise segmentation of different features in arid areas. In particular, it is of great significance to evaluate the governance effect of ecological restoration projects. [ABSTRACT FROM AUTHOR]

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Frequent flood hazards in the Raoyang River Basin in western Liaoning, China, have posed serious threats to people's lives and property. In an effort to study the simulation efficiencies of hydrological models in this arid and semi-arid catchment, this study examined the performance of the Xin'anjiang model, the Liaoning unsaturated model, and the DHF model in the Dongbaichengzi station watershed in the upper reaches of the Raoyang River, China. Additionally, this paper proposed an improved DHF model, which considers the impoundment and regulation of small- and medium-sized reservoirs in the upper reaches of the basin. The flood simulation results demonstrated that the Xin'anjiang model was difficult to apply in this area because the average value of its Nash–Sutcliffe efficiency (NSE) was as low as 0.31. Meanwhile, the simulation efficiencies of the Liaoning unsaturated model and the DHF model were higher than that of the Xin'anjiang model, but the relative error of flood peak discharge and runoff depth for most floods were still high and could not meet the actual forecast requirements by the Reservoir Administration Bureau of Liaoning Province. Overall, the improved DHF model showed the best efficiency, and the mean value of the NSE reached 0.79. Therefore, the improved DHF model has good applicability in the Dongbaichengzi station watershed in the upper reaches of the Raoyang River, China. [ABSTRACT FROM AUTHOR]

In recent years, Africa has seen much construction of large-scale hydrological infrastructures in the arid and semi-arid regions of numerous countries. This paper aims to quantify the effects of this form of hydrological infrastructure, especially the Upper Atbara and Setit Dam Complex (UASDC) in Eastern Sudan, on the land use/cover (LUC) and socioeconomic domains. This paper attempts to advance our understanding of this phenomenon by using multiple approaches. A framework using the integration of 3S technologies and a logical approach for quantifying the significance of the results to society has been developed. The method used Landsat5 TM in 2002, Sentinel2A in 2018, and statistical data to create the LUC map. The final map included seven classes; the overall accuracy of changes in LUC patterns was 94.9% in 2002 and 93% in the results reveal that significant changes occurred in terms of LUC, having a considerable effect on socio-economic development. The results were analyzed with the logical approach for overall objectives, where 85% represents S1, 3.3% represents S2, and 11.7% represents S3, respectively. This study provides an insight into further investigations of the dam's effect on climate and groundwater, and offers a new perspective on land use prediction, simulation, and environmental sustainability. [ABSTRACT FROM AUTHOR]

Nowadays, rainwater harvesting systems, particularly on the roof of the buildings in residential areas could be considered as a managerial procedure to reduce water crisis. This efficient method is being investigated and implemented in different countries all around the world. This study was conducted on the estimation of rainfall, runoff coefficient, and the calculation of the optimized tank volume and the total harvested amount of rainwater on the roofs of the residential areas in Torbat-e Jam. It is noteworthy to mention that the roofs’ surfaces are covered by waterproofing. This study aimed to estimate the amount of the harvested rainwater in the study area, and to apply this method in different areas of Torbat-e Jam, Razavi Khorasan Province, Iran. According to the results, the values of the roofs’ runoff coefficient and average rainfall were 0.9 and 154 mm, respectively. The results of the tank volume sensitivity analysis showed that the average peak 24-hour rainfall is the best rainfall index to calculate the tank volume. The total harvested amount of rainwater was 5,606 m3 considering the total surface of the roofs and the annual rainfall in the study area. Applying this procedure in other areas of Torbat-e Jam, the harvested rainwater was estimated as 772,806 m3. This amount of harvest resulted in 15.5% water saving.

The westerly winds and East Asian summer monsoon play a leading role in climate change of southwestern North America and eastern Asia since the Last Glacial Maximum (LGM), respectively. Their convergence in arid and semi-arid regions of the Asian continent (AAC) makes the regional climate change more complicated on the millennial-scale. There are still limitations in applying paleoclimate records and climate simulations of characteristic periods to investigate climate change patterns since the LGM in this region. In this study, we adopt two indexes indicating effective moisture and rely on a continuous simulation, a time slice simulation, and numerous paleoclimate records to comprehensively investigate the climate change modes and their driving mechanisms since the LGM in AAC. Results demonstrate a millennial-scale climate differentiation phenomenon and three climate change modes possibly occurring in AAC since the LGM. The western AAC largely controlled by the westerly winds is featured as wet climates during the LGM but relatively dry climates during the mid-Holocene (MH), coinciding with the climate change mode in southwestern North America. Conversely, dry conditions during the LGM and relatively wet conditions during the MH are reflected in eastern AAC governed by the East Asian summer monsoon, which leans to the climate change mode in eastern Asia. If climate change in central AAC is forced by the interaction of two circulations, it expresses wet conditions in both the LGM and MH, tending to a combination of the southwestern North American and eastern Asian modes. Precipitation and evaporation exert different intensities in influencing three climate modes of different periods. Furthermore, we identify the significant driving effects of greenhouse gases and ice sheets on westerly-dominated zones of AAC, while orbit-driven insolation on monsoon-dominated zones of AAC. [ABSTRACT FROM AUTHOR]