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Purpose: Water retention capacity (WRC) is crucial for assessing the hydro-physical behavior of unsaturated soils. Dispersive soil, erodible and found mainly in arid regions, lacks sufficient WRC knowledge, hindering its stability evaluation in unsaturated state. This study aimed to explore the WRC of dispersive soil by measuring its matric suction (ψ) under coupling effects of dry density (ρd) and soluble salt content (η). Materials and method: Compacted specimens with different ρd and η were prepared. For each ρd-η case, six levels of soil mass water content were considered and the ψ was measured via filter paper method. Soil water characteristic curves (SWCCs) were fitted by van Genuchten model. Results and discussion: The WRC of dispersive soil enhances as ρd increases. Increasing η first weakens then strengthens the WRC, showing suction dependence. The air-entry value and residual state suction range within 0.95–17.8 kPa and 15.7–98.4 MPa, respectively. As for the air-entry value, increasing η from 0.3% to 2.0% decreases it from 36.0% to 58.7% when ρd increases, and its average growth rate changes from 174.5% to 265.3% when ρd exceeds 1.53 g/cm3. Increasing ρd reduces the average water loss rate of SWCC transition stage, while the impact of η is nonmonotonic, with an inflection point at 1.0%. Conclusions: The ρd and η influenced the WRC of dispersive soil individually and interactively. The effect of ρd links to the water release sequence from pores of different sizes, whereas that of η, rather complex and non-monotonic, relates to clay electrochemistry and salt phase. [ABSTRACT FROM AUTHOR]

Groundwater is crucial for multiple uses over the world, especially in arid and semiarid regions. However, human activities significantly decreased groundwater quality. In this study, the spatiotemporal variation of groundwater quality was evaluated in an arid area where long-term paper wastewater irrigation has been implemented. For this study, seven wells were regularly monitored for physicochemical parameters over a period of 1 year. Statistical and graphical approaches were applied to interpret the spatiotemporal variation of groundwater quality parameters in the wastewater irrigation zone. Correlation analysis was also carried out to reveal the sources of some major ions. The results indicate that the groundwater type in the study area is dominated by the Cl-Na, followed by the HCO-Na, the HCO-Ca·Mg, and the SO·Cl-Ca·Mg types. Groundwater in the area is significantly contaminated locally with fluoride, nitrite and ammonia, and the chemical oxygen demand levels were increased in some groundwater monitoring wells. Most contaminants showed an increasing trend from the Yellow River water irrigation zone toward the wastewater irrigation zone. Rock weathering, mineral dissolution, and cation exchange are important processes controlling groundwater quality, but human activities, such as wastewater irrigation, play an undeniable role in affecting groundwater quality in this area. The results of this study contribute to the understanding of the formation and circulation of groundwater under human activities and provide a scientific basis for regional water quality evaluation, water quality improvement, and protection. [ABSTRACT FROM AUTHOR]

Dry root rot (DRR) caused by Rhizoctonia bataticola [(Taub.) Butler] is an emerging disease of chickpea (Cicer arietinum L.) and a serious constraint to chickpea production in warm and arid regions. To identify the genomic regions conferring resistance to DRR, a total of 182 F9 derived Recombinant Inbred Lines (RILs) were developed from the cross between a susceptible line BG 212 and moderately resistant breeding line ICCV 08305. The parental lines and RILs were screened against Rb 6 isolate of R. bataticola using paper towel method under controlled environment at ICRISAT during 2016 and 2017. The RILs were genotyped with cost-effective SNP genotyping platform, Affymetrix® Axiom®CicerSNP array. As a result, a high-density genetic map with 13,110 SNP markers spanning 1224.11 cM with an average inter marker distance of 0.09 cM was developed. A single minor QTL ('qDRR-8') explaining 6.70% PVE with LOD scores 3.34 was identified on CaLG08 for DRR resistance which could be further explored for mining candidate genes and the linked SNP markers could be further validated for application in marker-assisted selection of DRR resistance in chickpea breeding programs. [ABSTRACT FROM AUTHOR]

This paper presents the results of a detailed review of the research literature on how nomadic pastoralists are being affected by climate change, how they are adapting, and challenges with using traditional knowledge in adaptation. It focuses on research that investigates local, and particularly traditional, knowledge of water, pasture, their variability, and livestock. This knowledge underpins nomadic livelihoods, so is a foundation for effective adaptation. Changes in the total amount of precipitation, and particularly shifts in its timing, and increases in the frequency and intensity of extreme events, are having the greatest impacts on herding livelihoods. Herders in drylands worldwide face common adaptation challenges: declining traditional water sources and pasture degradation. Herders' adaptation strategies fall into five major categories: movement to areas with better water and pasture, improving seasonal access to water, improving seasonal access to feed, shifts in herd composition, and livelihood diversification. Movement is central to nomads' adaptation, yet, as climate change takes hold, restrictions on movement are increasing for both socio-economic reasons and climate reasons. Many papers emphasised the importance of combining traditional knowledge and current science to guide adaptation decision-making at household, locality, and national levels. There is widespread concern about the decline in traditional knowledge. All the papers reviewed emphasised the need to support passing on traditional know-how. Herder women's know-how, in particular, is marginalised in the research literature, so their traditional knowledge should be a focus in further research. Herders' adaptations are mostly localised, incremental, and have a relatively short-term focus. As nomadic pastoralism moves further outside the range of historical experience, the possibility of more profound transformations looms. [ABSTRACT FROM AUTHOR]

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Drought is one of the most critical meteorological hazards that has a devastating effect on natural habitats, ecosystems, and many economic and social sectors. Due to these severe impacts of drought events, many studies have focused on drought monitoring, prediction, and risk analysis to aid drought preparedness plans and mitigation measures. This paper presents a new drought composite index (DCI) to measure the intensity and frequency of the hazard component of meteorological drought. The DCI considers multiple indicators, such as precipitation, temperature, evapotranspiration, wind speed, relative humidity, and sunshine duration. The DCI is validated through an application to the Brazilian semiarid context. Based on the expert's opinion, we define the weight of each indicator using the analytical hierarchy process. The results were compared with two other drought indices to provide an initial validation because the other indices are not exclusively meteorological indices. The DCI estimates for January 2019 show that the semiarid central region is the most critical. The findings also indicate that the drought intensity is growing in this region. [ABSTRACT FROM AUTHOR]

Open water transposition channels in hot and arid regions, like those in the São Francisco River Integration Project (PISF) in Brazil, suffer significant water losses through evaporation. This paper proposes covering these channels with photovoltaic (PV) panels to reduce evaporation while simultaneously generating clean energy. The research aims to quantify water savings and energy generation potential across all channel lengths and assess whether the generated solar power can substitute grid electricity for powering the transposition pumps during peak hours, thereby enhancing energy efficiency. This study analyzed the state-of-the-art of PV generation and calculated their solar potential. Identified the specific characteristics of PISF channels and watercourses considering the regional geography, meteorology, irradiation, and social peculiarities. And, finally, assessed the feasibility of covering the watercourses with solar panels. The results reveal that covering all current PISF channels with PV panels could save up to 25,000 cubic meters of water per day, significantly contributing to water security and improving the quality of life for the local population. Additionally, the project could generate 1200 gigawatt-hours of electricity annually, meeting the energy demands of the transposition pumps during peak hours and promoting energy efficiency within the project. This research paves the way for utilizing PV technology to address water scarcity challenges and enhance the sustainability of water infrastructure projects in arid regions worldwide. [ABSTRACT FROM AUTHOR]

This study aims to quantify meteorological–hydrological drought propagations and examine the potential impacts by climatic variability, LULC change (LULC), and human regulations. An integrated observation-modeling framework quantifies drought propagation intervals and assesses mechanisms influencing hydrological droughts. Meteorological droughts are characterized using the Standardized Precipitation Evapotranspiration Index (SPEI), and hydrological droughts are assessed through the Standardized Streamflow Index (SSI) across diverse climatic zones. Cross-correlation analysis between SPEI and SSI time series identifies the lag time associated with the highest correlation as the drought propagation interval. Mechanisms are investigated via a coupled empirical-process modeling framework incorporating the Soil and Water Assessment Tool (SWAT). Discrepancies between simulated and observed SSI time series help quantify the extent of human regulation impacts on hydrological drought characteristics and propagation. The Yellow River Basin (YRB), divided into six subzones based on climate characteristics, is selected as the case study. Key findings include: (1) Meteorological droughts were extremely severe across most YRB during the 1990s, while the 2000s showed some mitigation primarily due to precipitation increases. (2) Hydrological droughts and propagation times from meteorology to hydrology demonstrated substantial spatiotemporal variability. In general, summer propagation times were shorter than other seasons. (3) Propagation times were shorter in arid regions with cropland or built-up land cover versus grassland and woodland, while the reverse held for humid regions. (4) Human regulations prolonged propagation times, likely due to reservoir regulations designed to overcome water deficits. While the YRB is the focus of this paper, the methodologies and findings are applicable to other regions worldwide to enhance drought forecasting and water resource management. In various hydrological and climatic contexts worldwide. [ABSTRACT FROM AUTHOR]

The Ebinur Lake Basin is an ecologically sensitive area in an arid region. Investigating its land use and land cover (LULC) change and assessing and predicting its ecosystem service value (ESV) are of great importance for the stability of the basin's socioeconomic development and sustainable development of its ecological environment. Based on LULC data from 1990, 2000, 2010, and 2020, we assessed the ESV of the Ebinur Lake Basin and coupled the grey multi-objective optimization model with the patch generation land use simulation model to predict ESV changes in 2035 under four scenarios: business-as-usual (BAU) development, rapid economic development (RED), ecological protection (ELP), and ecological–economic balance (EEB). The results show that from 1990 to 2020, the basin was dominated by grassland (51.23%) and unused land (27.6%), with a continuous decrease in unused land and an increase in cultivated land. In thirty years, the total ESV of the study area increased from 18.62 billion to 67.28 billion yuan, with regulation and support services being the dominant functions. By 2035, cultivated land increased while unused land decreased in all four scenarios compared with that in 2020. The total ESV in 2035 under the BAU, RED, ELP, and EEB scenarios was 68.83 billion, 64.47 billion, 67.99 billion, and 66.79 billion yuan, respectively. In the RED and EEB scenarios, ESV decreased by 2.81 billion and 0.49 billion yuan, respectively. In the BAU scenario, provisioning and regulation services increased by 6.05% and 2.93%, respectively. The ELP scenario, focusing on ecological and environmental protection, saw an increase in ESV for all services. This paper can assist policymakers in optimizing land use allocation and provide scientific support for the formulation of land use strategies and sustainable ecological and environmental development in the inland river basins of arid regions. [ABSTRACT FROM AUTHOR]

Tecoma stans is a widely distributed tall ornamental shrub in the plains of Indian subcontinent and is considered an invasive species across Argentina, Australia, South Africa, Pacific Islands and tropical regions of Asia. Besides having an ornamental significance, T. stans has been extensively investigated for its pharmaceutical applications as a source of bioactive compounds. In addition, the shrub is cultivated commercially as a potted flowering plant. We believe that T. stans, being a hardy, invasive and aggressively growing species, holds a considerable potential and a promising solution for re-greening waste and degraded lands outside its invasive range, due to its wider adaptability and drought tolerant characteristics. The shrub is an excellent source of pollen and nectar, that attracts diverse insect-pollinators and several species of birds. The prudent plantation of this shrub has the potential to restore the ecology of barren landscapes, that can change its perspective of 'being invasive' to 'being ecologically healthy' across the tropical, semi-arid and subtropical regions worldwide. This paper reviews the current updates on ecology, life cycle including morphology, plant growth characteristics, flowering phenology, reproductive biology, breeding system and fruiting of T. stans. In addition, details on insect-pollinator diversity and natural regeneration potential have also been discussed, besides highlighting its therapeutic and landscape use. [ABSTRACT FROM AUTHOR]

Groundwater evapotranspiration (ETg) is a significant component of water and energy balance analyses in arid and semiarid environments; however, it is also one of the most challenging items to estimate. Estimation of ETg using diurnal groundwater-level fluctuation is considered cost-effective and straightforward, while more accurate estimation technology continues to be developed due to the complex set of factors that influence the variation of groundwater level. This paper proposes a method for calculating ETg that combines the analytical solution of the Boussinesq equation and dynamic harmonic regression analysis, which is a nonstationary approach to groundwater-level signal extraction. The presented approach can calculate ETg values with a high time resolution consistent with the groundwater-level monitoring frequency, and it is robust enough to handle large amounts of measurement data. More importantly, this method eliminates the influence of recharge during the groundwater-level-rise stage. The method is tested in bushland dominated by Sminthopsis psammophila in Mu Us Desert (northern China), which has a shallow water table. The results show that this method is easy to perform and it obtains a reasonable estimate of ETg in the unfrozen seasons, regardless of the disturbance of recharge that results in a sharp rise in groundwater level. However, the method does not work well in the frozen seasons because of the physical mechanisms of change in groundwater movement in the vadose zone and a strong barometric effect. Overall, the method provides a step toward accuracy of ETg estimation using diurnal groundwater-level fluctuation, and this paper provides guidelines for its use. [ABSTRACT FROM AUTHOR]

Hindgut of wild ruminants harbours diversified anaerobic bacteria with promising fiber degrading ability. Fibrolytic enzyme activity is strongly influenced by diet and host species which till date remains unexplored for harnessing their optimum benefits. The present study was conducted to isolate and characterize fiber degrading anaerobic bacteria from faeces of wild blue bull (Boselaphus tragocamelus) inhabiting in semiarid regions. A total of 167 isolates were obtained from 85 faecal samples using M-10 medium, on the basis of clear zones formed on Congo red plates 20 isolates were selected and designated as NLG1-20 for microscopic and biochemical characterization. Further, molecular confirmation was done by PCR analysis with universal 16S rDNA primers. All isolates were obligatory anaerobes except, NLG4, NLG19 and NLG20. Majority of the sugars tested were utilized by most of the isolates except arabinose. Fibrolytic enzyme activities revealed that NLG1 had highest endoglucanase activity, NLG13 had highest exoglucanase activity while NLG8 showed maximum xylanase activity. In case of FPase assay, highest and lowest values were observed in isolate NLG11 (8.96 U/mL) and NLG8 (5.58 U/mL), respectively. Phylogenetic analysis of the isolates revealed a highly diverse group of microbes mainly belonging to the family Paenibacillaceae which have not been previously characterized in ruminants for fiber degradation. Therefore, results obtained in the present study indicated that the screened isolates showed promising fiber degrading potential in terms of filter paper assay and fibrolytic enzyme activity which can be explored further for improving lignocellulose digestibility in ruminants as an additive. [ABSTRACT FROM AUTHOR]

Spent coffee ground (SCG) consists of the remainder left after brewing the coffee grounds. Due to its valuable composition, SCG can provide sufficient nutrients and support plant growth, particularly in arid agricultural lands where soil fertility needs to be improved. However, the effects of SCG are highly dependent on their nature (raw or treated) and the application rate. SCG treatments namely composting and vermi-composting or pyrolysis could result in a more useful product for agricultural use, making it easy to overcome the SCG phytotoxic effect. In this paper a critical review of the researches on SCG was presented. The aim of this review was (1) to highlight the difference between the characteristics of composted, vermi-composted and pyrolyzed SCG with respect to the raw one, and (2) to outline their impacts on both of the physico-chemical properties of the soil as well as the growth of plant. In summary, adding raw SCG may have benefits for physical chemical properties of the soil but not for plant growth, because of the phytotoxic components including polyphenols. Therefore, the application of raw SCG for plant production purposes, even at low rates (equivalent to 2.5%) is not recommended. The negative effect on plant growth can be overcome by SCG vermi-composting or composting/pyrolysis at 270 and 400 °C. Therefore, vermi-composting can be efficiently applied for SCG pre-treatment before their reuse as a soil fertilizer to ameliorate the properties of the soil and subsequently plant nutrition. [ABSTRACT FROM AUTHOR]

The desert sand-skipper Croitana aestiva Edwards is endemic to central Australia, a region with a semi-arid climate. The species was known from a total of eight specimens collected in 1966 and 1972 at three locations west of Alice Springs but was then not positively recorded for the next 35 years, leading to its listing nationally as an Endangered species. In February 2007 a population was rediscovered during targeted surveys following a significant rainfall event, leading to the broader question of how climate influences its life cycle. In this paper I describe the species' distribution, listing all the localities at which the species was observed during targeted surveys from 2007 to 2010. Adult phenology of one population over this period is presented, along with that for the closely related inland sand-skipper Croitana arenaria arenaria Edwards, which occurs in the same area. The desert sand-skipper is now known from 13 extant locations, of which 11 are new. This species has a calculated Extent of Occurrence of 1141 square kilometres and an Area of Occupancy of 48 square kilometres, but the true distribution is likely to be greater. Adults of both Croitana Waterhouse taxa are entirely dependent on adequate rainfall for emergence, with more adults after greater rainfall. Both taxa are threatened by the increased frequency and intensity of wildfires promoted by buffel grass (Cenchrus ciliaris L.) (Poaceae) an exotic pasture grass, as well as climate change. Implications for insect conservation: Baseline distributional information presented in this paper will be essential for monitoring and future assessments of conservation status. Understanding adult phenology will be crucial to future conservation efforts as the impacts of climate change in central Australia become clearer. [ABSTRACT FROM AUTHOR]

The degree of coupling coordination between Drinking Water Carrying Capacity (DWCC) and Population Spatial Agglomeration (PSA) is a primary indicator for assessing the sustainable development of society. However, current research using quantitative model methods to explore relationships between the DWCC and the PSA is extremely rare. In order to provide theoretical and methodological support for research of regional population control or water resource allocation, based on the idea of coupling and coordination in physics, this paper constructs a Comprehensive Evaluation Model of Drinking Water Carrying Capacity (CEMDWCC), a Population Spatial Aggregation Index Model (PSAIM) and a Coupling Coordination Model of Human Water Relationship (CCM-HWR). Then, we use of the output results of the CEMDWCC and the PSAIM as the input parameters for the CCM-HWR to integrate these three models together. Through the above processing, we deduce a quantitative analysis method for the degree of coupling and coordination between the DWCC and the PSA. On this basis, we further use Kunming, a region of the water-deficient severely as a research area to discuss the coupling coordination relationships of the DWCC and the PSA during 20 years from 1996 to 2015. The results demonstrate that, on the one hand, in the time dimensions, the coupling degree of the DWCC and the PSA fluctuates little, and it is basically in a straight development state during the 20-year study period. Moreover, the degree of coordination between them is moderately unbalanced and has not fluctuated much for many years in this period. This shows that the DWCC and the PSA have not yet reached a positive interaction state, which is not conducive to sustainable development in the future. On the other hand, in the spatial dimensions, there are certain spatial differences in different regions. These differences are explicitly manifested in the degree of coupling and coordination, which is the better in regions with more developed economies. On the whole, the results of the study are more consistent with the actual situation in the study area. In other words, the economically developed regions have relatively high population spatial concentration, and the DWCC has also reached a relatively high state. Moreover, in these areas, the coupling relationship between the DWCC and the PSA remains relatively stable, and the coordination relationship between them is more harmonious and orderly. As can be seen from the above research results, the research method in this paper can quantitatively analyze the coupling and coordination relationships between the DWCC and the PSA. Therefore, this method is of great importance for promoting research for the sustainable development of population, resources, environment, economy, and society in arid regions of the world. [ABSTRACT FROM AUTHOR]

This paper analyzes spatial and temporal changes of aridity in Argentina (1961–2022). The aridity degree, using Climatic Research Unit (CRU) monthly data, was defined through six climate types classified by De Martonne Aridity Index (DMI). Argentina presents a very arid, arid and semiarid region that extends from Puna to Patagonia, alongside two humid and very humid regions: one located in the Chaco-Pampas Plains and Mesopotamia, and another in the Patagonian Andes. Between these regions, there are subhumid areas with marked aridity variations. These structures persist over time, but advances or setbacks were observed in their bordering areas, with significant changes in the Andes (leading to more arid conditions) and the southwestern Pampas Plains (leading to more humid conditions) during the historical period. The contribution of temperature and precipitation changes to these DMI changes was quantified, indicating that precipitation modulated the DMI spatial changes, while temperature intensified or weakened the change magnitudes. The extension variations of the arid and semiarid regions in Argentina were related to three climate variability modes (El Niño – Southern Oscillation [ENSO], Pacific Decadal Oscillation [PDO] and South Atlantic Ocean Dipole [SAOD]). Significant correlations were found with PDO (r < 0) and SAOD (r > 0), which indicate that an increase in the area occupied by arid and semiarid climates are associated with PDO negative phase or SAOD positive phase. Moreover, when these phases occur simultaneously, the expansion of arid and semiarid regions is larger than under the action of an individual forcing. [ABSTRACT FROM AUTHOR]

Studying the internal relationship between urbanization process and cultivated land change can reveal the differential law of different urbanization processes and effectively protect cultivated land resources. Using the land-use change analysis method, this paper analyzed the quantity and quality change of cultivated land during the process of urbanization in the Bohai Rim region from 1990 to 2020 and explored its driving mechanism. The results show that the urbanization level in the Bohai Rim region increases by 31.06%, and 120 km2 farmland will be occupied for every 1% increase in urbanization level. The level of urbanization is higher in Beijing and Tianjin, medium in Liaoning and Shandong, and lower in Hebei. The area of cultivated land decreased year by year, and the decrease in dry land was the largest, followed by paddy land. Hebei, Shandong, and Liaoning have a high contribution rate to the reduction in cultivated land around the Bohai Sea. Population urbanization, spatial urbanization, and other factors have a significant impact on the study area, while economic urbanization and life urbanization show different laws. It is suggested that the development of urbanization can be promoted in a timely and appropriate manner, and the harmonious development of urbanization can be promoted by optimizing the layout of land use and avoiding excessive occupation of cultivated land at the expense of food security and ecological environment. [ABSTRACT FROM AUTHOR]

Several soiling mitigation solutions and cleaning techniques have been developed to maintain high efficiency of photovoltaic (PV) panels. First of its kind, the investigation of the adaptability of the cleaning systems to solar trackers has been performed. The majority of these systems are dedicated to fixed installations whereas only few systems that can be adapted to solar trackers are presented in the updated cleaning systems background. For this reason, this paper presents an innovative approach which consists of combining trackers with an integrated cleaning system that has been designed. Based on the conducted experimental study, a maximum of 7% in soiling losses has been found for the PV generator of 4 kWp equipped with a dual-axis tracker installed in Rabat-Morocco over almost 1 year. Consequently, a reduced cleaning prototype has been realized and tested to evaluate the energy recovery based on the performed cleaning. The automatic cleaning has presented a similar efficiency with the manual cleaning with a slight difference of 0.95 pp and an increase of energy of 11.5% in the arid region. Through the economic analysis carried out taking into account the gain in energy production, the automatic cleaning cost was 0.14 USD/kWh. It has been found that the cleaning technique based on the telescopic arm would be more effective if the tracker is installed in an arid region where soiling is higher than Rabat. In this case, the payback time of the cleaning solution is faster (8 to 9 years), hence its profitability. [ABSTRACT FROM AUTHOR]

Climate change and human activities have massively impacted the hydrological cycle. Thus, it is of the greatest concern to examine the effect of climate change on water management, especially at the regional level, to understand the possible future shifts in water supply and water-related crises and support regional water management. Fortunately, there is a high degree of ambiguity in determining the effect of climate change on water requirements. In this paper, the statistical downscaling (SDSM) model is applied to simulate the potential impact of climate on crop water requirements (CWR) by downscaling ET0 in the region of Western Maharashtra, India, for the future periods, viz., the 2030s, 2050s, and 2080s, across three meteorological stations (Pune, Rahuri, and Solapur). Four crops, i.e., cotton, soybean, onion, and sugarcane, were selected during the analysis. The Penman-Monteith equation calculates reference crop evapotranspiration (ET0). Furthermore, in conjunction with the crop coefficient (Kc) equation, it calculates crop evapotranspiration (ETc)/CWR. The predictor variables were extracted from the National Centre for Environmental Prediction (NCEP) reanalysis dataset for 1961–2000 and the HadCM3 for 1961–2099 under the H3A2 and H3B2 scenarios. The results indicated by SDSM profound good applicability in downscaling due to satisfactory performance during calibration and validation for all three stations. The projected ET0 indicated an increase in mean annual ET0 compared to the present condition during the 2030s, 2050s, and 2080s. The ET0 would increase for all months (in summer, winter, and pre-monsoon seasons) and decrease from June to September (monsoon season). The estimated future CWR shows variation in the range for cotton (− 0.97 to 2.48%), soybean (− 2.09 to 1.63%), onion (0.49 to 4.62%), and sugarcane (0.05 to 2.86%). The significance of this research lies in its contribution to understanding the potential impacts of climate change at a regional level. This study provides valuable insights into the expected changes in water demand for key crops. The research also manifests implementing an identical methodology for downscaling other environmental parameters using a similar approach. [ABSTRACT FROM AUTHOR]

The sustainable use of groundwater resources requires that the components of a regional water balance are understood with a high degree of accuracy, especially in arid and semi-arid regions. Although groundwater recharge is one of the most important components of a groundwater balance, its rate is one of the most uncertain components. Despite the simplicity and widespread use of water balance method (WB) for estimating groundwater recharge in arid and semi-arid regions, the accuracy of the groundwater recharge estimation depends on the accuracy of the other components in this method, so a reduction in errors that are associated with measuring these can improve the accuracy of recharge estimation. Therefore, the main objective of the current paper was to present a method for estimating groundwater recharge based on minimization of the sum total error of the system water and groundwater balance equations simultaneously. A set of correction coefficients that reflect the error in estimation of each component of balance equations, were applied to different components in annual scale. Reasonable ranges, obtained from error analysis, were considered for the correction coefficients and the sum of absolute errors in the overall system water balance and groundwater balance equations was minimized for the period of study. The proposed method was used to estimate groundwater recharge in Mahvelat basin in Khorasan Razavi province of Iran, as a case study. The minimization process used in this research reduced the error of system water and groundwater balance equations by 55% and 65%, respectively. Moreover, as the results of optimization process on the correction coefficients, the recharge coefficients due to precipitation and irrigation return flow were estimated to be 2% and 16.5%, respectively. [ABSTRACT FROM AUTHOR]

Hydrological drought is one of the most important natural phenomena affecting the various aspects of life on Earth, especially with the increasing impact of climate change around the world. Drought forecasting is one of the important strategies in preparing treatments to reduce the effects of drought on life, especially in water resource management. The process of forecasting hydrological drought is one of the complex issues in hydrology, especially in the semi-arid regions. In the current paper, a hybrid model was developed to predict hydrological drought, using two machine learning models, namely the K-Nearest Neighbor (KNN) and the K-means clusters. The results of the stream drought index for the (3, 6, 9, 12) months-time scale were used to predict the hydrological drought of the study area. The flow data of the Great Zab River in Iraq was used as the case study. The results showed the efficiency of the proposed hybrid model in predicting hydrological drought compared to using the KNN model. The results showed that the results of the hybrid model are better than the results of the KNN model by 85%. Thus, the proposed hybrid model has overcome the difficulty of predicting hydrological drought in semi-arid regions. [ABSTRACT FROM AUTHOR]

This paper investigated whether rainfall promotes dilution or increase in nutrient concentrations and which land use indicators are the main predictors of nutrients in intermittent rivers in a large Brazilian semiarid region. The total phosphorus (TP) and total inorganic nitrogen (TIN) were monitored between 2013 and 2018 at 92 river water quality monitoring sites. The monthly rainfall (Rn) was obtained from 575 rain gauges. Pearson's correlation (R) between Rn and nutrient concentration was performed. The correlation patterns were also analysed based on land use data: urban area (%), agricultural field area (%), demographic density (inhabitants/km2), sewer system coverage (%), and reservoir density (reservoir/km2). Backward stepwise regression was performed to identify predictors of nutrient concentrations. The results revealed a marginal effect of rainfall on nutrients when the effects of urbanisation outweigh all other aspects. However, in regions with greater accumulated rainfall and lower reservoir density, the rainfall was related to a linear increase in nutrient concentrations (R > 0.8). Contrastingly, in the basins with less accumulated rainfall and greater inter-basin hydrological disconnection, there was a linear reduction in nutrient concentration (R < − 0.5). In the backward stepwise regression, sewer system coverage and Rn had the greatest influence for TP, and the urban area was the strongest predictor for TIN. Importantly, our results demonstrated that in semiarid rivers in densely populated regions, there is no single pattern of variability in nutrient concentration, on a wide scale of assessment. Therefore, adaptative and decentralised management can be more effective in improving water quality in these regions. [ABSTRACT FROM AUTHOR]

The paper compares different approaches to the reconstruction of environmental conditions from rodent fossil complexes, namely, the bioclimatic method and the method of reconstructing soil and plant conditions considering voles. For the reconstruction, data from ten localities in Western Siberia dated to the second half of the Middle Pleistocene were analyzed. The bioclimatic method allowed us to reconstruct the arid climatic zone in the south of Western Siberia (the Pre-Altai Plain and the Middle Irtysh) and the moderately cold and arctic climate for the localities situated northwards. The method of reconstruction of soil and vegetation conditions showed the predominance of xerophytic plant communities for the southern localities and mesophytic, mesohygrophytic, and hygrophytic for the northern ones. As additional indicators of environmental conditions, specialized species were proposed: subterranean animals (Siberian zokor and northern mole voles) and briophages (West Siberian lemming). [ABSTRACT FROM AUTHOR]

Most studies and conceptualizations of tipping points in environmental and climatic systems have been conducted using natural science perspectives and approaches. Socio-scientific contributions—including Anthropology—are scarce. This has resulted in a limited understanding of the socio-cultural dimensions of tipping point phenomena at the local level. This paper contributes to ongoing discussion and provides an ethnographic study of local perceptions of desertification tipping points (DTPs) amongst Ovaherero pastoralists in Namibia's semi-arid Okakarara constituency. Following a qualitative approach, this study shows that experienced farmers are aware of these phenomena and have accumulated extensive knowledge enabling them to identify and anticipate DTPs in different, complementary ways. The paper discusses how DTPs are managed in a communally farmed setting and presents the challenges that livestock farmers face in practical prevention of DTPs. [ABSTRACT FROM AUTHOR]

Most studies and conceptualizations of tipping points in environmental and climatic systems have been conducted using natural science perspectives and approaches. Socio-scientific contributions—including Anthropology—are scarce. This has resulted in a limited understanding of the socio-cultural dimensions of tipping point phenomena at the local level. This paper contributes to ongoing discussion and provides an ethnographic study of local perceptions of desertification tipping points (DTPs) amongst Ovaherero pastoralists in Namibia's semi-arid Okakarara constituency. Following a qualitative approach, this study shows that experienced farmers are aware of these phenomena and have accumulated extensive knowledge enabling them to identify and anticipate DTPs in different, complementary ways. The paper discusses how DTPs are managed in a communally farmed setting and presents the challenges that livestock farmers face in practical prevention of DTPs. [ABSTRACT FROM AUTHOR]

This paper presents the linkages of climate change and desertification, sensitivity to desertification, and the combined effects of these environmental hazards on land productivity. The objective of this study is to investigate the multifaceted nature and impact of climate change and desertification in Babura and identify ways to reduce their impact on the environment. This study applied adjusted MEDALUS methodology (Mediterranean desertification and land use) using ten (10) indicators that affected the study area. Remote sensing and GIS were the main techniques used in indices computation and mapping. Erdas imagine 9.2 software was used for the supervised classification to first achieved categorization of image in land use land cover (LULC) thematic features. Shuttle radar topography mission (SRTM) data using spatial analyst tool in ArcMap (extension of ArcGis 10.3) was used to extract digital elevation model and generated from it slope gradient. The ten indicators were integrated into ArcMap and each weighted from 1 to 2 using weighted overlay in ArcMap; thus, the higher the weighting the higher the sensitivity to land degradation. The ten indicators were categorized into climate, soil, and vegetation indicators based on most significant available parameters quantified and assessed on their perceived influence on desertification. The reclassification of climatic indicators, particularly the areas of high rainfall against the areas of low rainfall, assumed higher weighting indicating higher sensitivity to land degradation. Approximately 48.72% of the study area, with Babura being particularly critical, is highly sensitive to desertification, while most of the study area (676.79–5950.44 m2) consists of areas with very low erosion protection quality. [ABSTRACT FROM AUTHOR]

Abnormal changes in temperature, precipitation, atmospheric carbon dioxide, or solar radiation are examples of climate change that may affect irrigation water demand. Studies show an increasing trend in the earth's surface temperature, with decreasing trends in rainfall. With most studies focused on predicting the extent of climate change, fewer studies focused on developing appropriate response strategies. This paper aims to propose a systematic approach to identify, analyze, and respond to the risks of climate change on irrigation water in arid regions using the Risk Management process. The compound effect of these risks was analysed using Monte Carlo Simulation, which indicated a 69% loss in crop production due to climate change at a 90% confidence level. The proposed responses to the risks of climate change include strategies to avoid, transfer, mitigate, and/or accept these risks. The study has made three contributions to the state of the art. First, to adopt a well-recognized risk management methodology in climate change studies. Second, to quantify the compound effect of climate change risks on irrigation water in arid regions. Third, to recommend a set of response strategies to help policymakers mitigate the inevitable harmful effect of climate change on irrigation water. [ABSTRACT FROM AUTHOR]

Qanat system, as a great human heritage, contributes to the sustainable management of groundwater in the arid and semiarid regions of the world. The main aim of this paper was to efficiency assessment of the environmental variables in the construction of the Qanat system in Iran. Using the geographical information system (GIS) and statistical method of receiver operation characteristic (ROC), the efficiency of 20 environmental variables was assessed based on divisions of 30 major hydrological basins. Results revealed that most physical parameters and anthropogenic characteristics have significant effects on the construction of Qanat water lines with an AUC index > 0.6. The Pearson correlation test also confirmed the positive and significant relationships between the Qanat system and mentioned environmental parameters. From a geological viewpoint, the results highlighted the effective role of Quaternary aged alluvial sediments with very high permeability and low density of crust rocks in arid soils of arid and semiarid regions, such as playa fields in NamakTehran, Kavir, Lut, and Siahkuh basins. Regarding the spatial expansion of the Qanat system in Iran, the higher effects of some test variables, such as the climatic element of temperature, fault density, and drainage density, were rejected due to poor discrimination values of the AUC index < 0.6. [ABSTRACT FROM AUTHOR]

Arid region water reservoirs have different characteristics and solutions from humid regions with the most water shortage in the world socio-economically. This paper outlines possible implementation methodologies, procedures and guidance for water storage in natural and artificial reservoirs for better operation and management rules taking into account the impacts of climate change. The literature is full of methodological applications regarding the impact of climate change on the hydro-meteorological records, but the same is not available in reservoirs (surface and underground), which is the scope of this paper. In addition, reservoir structures offer the necessary mitigation and adaptation activities against the effects of climate change to design, construct, maintain, operate or increase their existing capacity. To increase groundwater reservoir capacity in local aquifers, precipitation, associated flooding and flash flooding should be diverted to artificial groundwater recharges through precipitation and surface runoff harvesting activities. Definitions of fully or partially penetrating underground dams are also explained. The real groundwater feeding application is offered from the Kingdom of Saudi Arabia as arid region representative. Finally, a series of recommendations are presented for the future design and management of reservoirs. [ABSTRACT FROM AUTHOR]

Climate change poses a major threat to the semi-arid tropics, which is characterized by scanty and uncertain rainfall, infertile soils, poor infrastructure, extreme poverty and rapid population growth. These conditions present serious environmental, economic and social impacts on the agricultural community. In recent years, adaptation to climate change has become a major concern to farmers, researchers and policy makers alike. To enhance policy towards tackling the challenges that climate change poses to farmers, it is important to have knowledge on their perceptions of climate change, potential adaptation measures and factors affecting adaptation. In addition, the extent to which farmers' perceptions on climate change coincide with actual climatic data needs to be further examined. This paper, using a qualitative approach, looks into the perceived changes in rainfall and temperature, their impacts and adaptations strategies taken up by farmers in four villages in the states of Maharashtra and Andhra Pradesh. It also analyses the accuracy of these perceptions based on actual available climatic data. The paper also looks into the determinants of adaptive capacity by examining a case of improved water management as an adaptation mechanism. [ABSTRACT FROM AUTHOR]

Statistical downscaling of General Circulation Models (GCM) simulations is widely used for projecting precipitation at different spatiotemporal scales. However, the downscaling process is linked with different source of uncertainty including structural/parametric uncertainty of the model and output uncertainty. This research proposes a novel framework to assess the parametric uncertainty of downscaling model, and used this framework to assess the performance of different bias correction methods linked to the regression-based statistical downscaling model. The used downscaling framework in the current paper is Statistical Downscaling Model (SDSM). The conventional bias correction method linked with SDSM is the Variance InFlation method (VIF), this paper substitutes this method with three different bias correction methods including Local Intensity Scaling (LOCI), Power Transformation (PT), and Quantile Mapping (QM) to assess the associated parametric and global uncertainty of each method in different climate by using a new approach. The proposed method is applied to six different stations located in Iran and United States with different climate status. Average Relative Interval Length (ARIL), P-level, and Normalized Uncertainty Efficiency (NUE) are used as uncertainty indicators to evaluate the results. Results represent that in every assessed climate class, LOCI, and PT, work better than conventional VIF in both amount and occurrence modules of SDSM framework. More precisely, LOCI works better in station that has wet summer, while PT performs well in the stations where there is no or very limited precipitation in summer. Substituting LOCI with VIF, result in increasing the value of NUE by at least factor of 3 in occurrence and amount model which means the significant reduction in structural uncertainty. Also applying PT in arid regions improves the NUE indicator at least by factor 2 in occurrence and amount model and by factor 3 in output uncertainty assessment, and results in less parametric and output uncertainty. Results illustrate the important role of bias correction approaches in reducing structural, and output uncertainty and improving the statistical efficiency of the downscaling model. [ABSTRACT FROM AUTHOR]

At present, buildings in arid and hot regions are facing severe challenges of indoor comfort improvement and carbon emission reduction, especially in rural areas. Multi-objective optimization could be an effective tool for tackling the aforementioned challenges. Therefore, this paper proposes a life-cycle optimization framework considering thermal comfort, which is beneficial to promoting residents' motivation for low-carbon retrofit in arid climate regions. First, in response to the above problems, three objective functions are specified in the framework, which are global warming potential (GWP), life cycle cost (LCC), and thermal discomfort hours (TDH). To improve the optimization efficiency, this research uses Deep Neural Networks (DNN) combined with NSGA-II to construct a high-precision prediction model (meta-model for optimization) based on the energy consumption simulation database formed by the orthogonal multi-dimensional design parameters. The accuracy index of the modified model is R2 > 0.99, cv(RMSE) ≤ 1%, and NMBE ≤ 0.2%, which gets rid of the dilemma of low prediction accuracy of traditional machine learning models. In the scheme comparison and selection stage, the TOPSIS based on two empowerment methods is applied to meet different design tendencies, where the entropy-based method can avoid the interference of subjective preference and significantly improve the objectivity and scientific nature of decision analysis. Additionally, sensitivity analysis is conducted on the variables, which supports guidance for practitioners to carry out the low-carbon design. Finally, the multi-objective optimization analysis for a farmhouse in Turpan is taken as a case study to evaluate the performance of the framework. The results show that the framework could significantly improve the building performance, with 60.8%, 52.5%, and 14.2% reduction in GWP, LCC, and TDH, respectively. [ABSTRACT FROM AUTHOR]

With the rapid development of urban agglomerations in northwest arid and semiarid regions of China, the scope of the urban heat island (UHI) effect has gradually expanded and gradually connected, and has formed a regional heat island (RHI) with a larger range of impact to the regional environment. However, there are few studies on the heat island effect of urban agglomerations in arid and semiarid regions, so this paper selects the urban agglomeration of Hohhot, Baotou and Ordos (HBO) of Inner Mongolia, China as the study area. Based on the 8-day composite Moderate-resolution Imaging Spectroradiometer (MODIS) surface temperature data (156 scenes in all) and land use maps for 2005, 2010, and 2015, we analyze the spatiotemporal distributions of regional heat (cool) islands (RH(C)I) and the responses of surface temperatures to land-use changes in the diurnal and interannual surface cities. The results showed that: 1) from 2005 to 2015, urban areas showed the cold island effect during the day, with the area of the cold island showing a shrinking feature; at night, they showed the heat island effect, with the area of the heat island showing a first decrease and then an increase. 2) From 2005 to 2015, the land development (unutilized land to building land) brings the greatest temperature increase (ΔT = 1.36°C) during the day, while the greatest temperature change at night corresponds to the conversion of cultivated land to building land (ΔT = 0.78°C) exhibited the largest changes at night. From 2010 to 2015, the land development (grassland to building land) bring the greatest temperature increase (ΔT = 0.85°C) during the day, while the great temperature change at night corresponds to the conversion of water areas to building land (ΔT = 1.38°C) exhibited the largest changes at night. Exploring the spatial and temporal evolution of surface urban heat (cool) islands in urban agglomerations in arid and semiarid regions will help to understand the urbanization characteristics of urban agglomerations and provide a reference for the formulation of policies for the coordinated and healthy development of the region and co-governance of regional environmental problems. [ABSTRACT FROM AUTHOR]

The agricultural sector is the backbone of the Indian economy, where precision agriculture is playing a vital role in boosting productivity. The soil chemical parameters play an important role in precision agriculture. Analysis and prediction of micronutrient of the soil chemical parameters are highly insisted upon by farmers and agriculture researchers. The soil nutrients parameters can be analyzed from multispectral data through ISO cluster unsupervised classification. Understanding the nutrient level of soil is highly recommended for farming; early understanding may help to improve soil fertility and fully meet productivity requirements. This paper addresses the soil nutrients analysis by the regression method and its spectral indexed based on the prediction model by Iterative Self-Organizing (ISO) cluster unsupervised classification algorithm. Therefore, for this study, the Baggi, Ibrahimpur, Wai, Mogra, and Bori (for validation) villages were selected. These villages are located in the Amravati district and fall under Maharashtra provenance of India. From the study area, three soil nutrients parameters such as P, Fe, pH indices-based data were acquired from the spectral calculation of Sentinel-2 and Landsat-8 bands. The P, Fe and pH indices were calculated from the yellowness index (YI), ferrous oxide index, and carbonate level. The ISO cluster unsupervised mechanism has been used for prediction of soil chemical parameter indices out of 100 samples. The study regions recognition rate is 97% for P, 94.05% for Fe, and 69% for pH. During the validation process, four villages' results were used for the identification of soil nutrient parameters for Bori village. The results of the study area can be helpful for the development of the planning of soil fertility in the agriculture fields and effectively increase the crop yield production in the semi-arid region. [ABSTRACT FROM AUTHOR]

In this paper frequency analysis of annual extreme daily rainfall of 14 gauging stations located in an arid zone of Iran were performed using parametric and nonparametric approaches. The parametric methods include normal, two- and three-parameter log-normal, two-parameter gamma, Pearson and log-Pearson type III, extreme value type I (Gumbel), generalized extreme value and generalized logistic distributions. The nonparametric approach is Fourier series method. The data were fitted to all of above mentioned models and the results showed that the goodness of fit of the data to Fourier series is much better than other parametric methods. Thus the Fourier series can be used as an alternative approach for frequency analysis of extreme daily rainfall in an arid zone. In addition, the quantiles can be calculated by the Fourier series. [ABSTRACT FROM AUTHOR]

Green walls are a traditional system that has been rediscovered for addressing and combating effects of climate change on the urban environment. The greening of walls is one of the sustainable techniques towards green architecture, and it has become a significant part of the passive design. This research employed an integrated approach to create healthy urban spaces and improve people's overall quality of life through introducing the concept of biofacades to make a city more sustainable. Today, accelerated growth in urban development is occurring in Doha, the capital city of Qatar, including in large-scale urban developments and architecture and infrastructure projects, causing significant changes to the built environment. This paper assesses the performance of biofacades in Doha's hot and arid climate. For this purpose, four biofacade walls were installed on the campus of Qatar University, with plant species that are suitable for this region. These walls were regularly monitored to observe the adaptation of the biofacades to prevailing climatic conditions in Qatar. The project had three main steps. Step 1 involved the selection of suitable plants that could survive in Doha; Step 2 entailed the distribution of plants in four different orientations across the building; and Step 3 included monitoring, testing, measurement, observation, and analysis to determine the most suitable plants for the biofacade. The findings of this research will enable architects and engineers to formulate guidelines for the selection of appropriate plants to improve energy performance and reduce the urban heat island effect in the arid climate of Qatar. [ABSTRACT FROM AUTHOR]

The conversion of natural lands to agricultural uses is a significant threat to soil biodiversity. Within agriculture, monoculture based systems are the most common which often result in low biodiversity because they impact the abundance, diversity, and composition of soil macrofauna (SMF). The objective of this paper was to analyze SMF abundance and diversity across different agroforestry practices (AFP) in the drylands of southern Ethiopia. The soil monolith and soil samples were collected from homegarden, cropland, woodlot, and trees on soil and water conservation based AFP using the standard Tropical Soil Biology and Fertility Institute manual, and the identification was done based on morphological characteristics and standard identification keys. The abundance, occurrence, and community composition of SMF were significantly different across the different AFPs (P < 0.05). In this study, 378 SMF belonging to 13 families, including unnamed were identified. The soil ecosystem of AFP was dominated by earthworms (relative abundance = 0.43), followed by termites (relative abundance = 0.12). The homegarden AFP type had a significantly higher number of SMF occurrence index of 46.03 (174), followed by woodlot, 26.72 (101) practices, and the lowest was recorded under cropland, 12.70 (48). The abundance, diversity, richness, and similarity of SMF were significantly related to soil total nitrogen and organic carbon. Phosphorus and pH were significantly related to the abundance and richness of SMF. The homegarden and woodlot AFP types were suitable for SMF biodiversity conservation. [ABSTRACT FROM AUTHOR]

Managed Aquifer Recharge (MAR) has emerged as a multi-facet, sustainable and effective technique to replenish dwindling groundwater resources. Suitable site selection is an important step in the design phase of MAR process. Conventional methods of site suitability studies using GIS and Multi Criteria Decision Analysis (MCDA) does not address the aquifer's response to MAR, while limited modelling-based studies have considered the effect of surface hydraulic factors. In this paper, a fresh approach is presented, that utilises decision model, K-mean clustering technique and numerical model to identify optimal sites for MAR interventions. The methodology was applied in a semi-arid region of Lower Betwa River Basin (LBRB), India. Four different parameter combinations were employed that incorporated the impact of surface and subsurface parameters. Multiple model runs were executed using MODFLOW–NWT to assess the groundwater head response to the infiltrated volume of water. The results indicated that under the least head change category (< 0.7 m), the north and south–east regions of the LBRB were the most appropriate sites. The coalition of geomorphology and drainage density along with aquifer properties such as hydraulic conductivity, specific yield and aquifer thickness were found to be the best suited combination for site selection in LBRB, with maximum spatial coverage (16%) under it. It was observed that the choice of parameter combinations affected the range of groundwater head variations and depended upon the site-specific criteria of accepted head change ranges for determining the best suitable parameter combinations for MAR site selection. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to analyzing uncertainty in complex groundwater models based on the approximate Bayesian computation (ABC) framework and information-theoretic summary statistics. Two summary statistics using the concepts of mutual information and variation of information are formulated as distance function measures of the ABC. These signatures are utilized within an ABC rejection (ABC-REJ) algorithm to measure the similarity and dissimilarity of the generated samples to the true posterior distribution of the groundwater model parameters. This method was applied to groundwater model calibration and uncertainty analysis in an arid region of Oman with a complex hydrogeological setting and a hardrock-alluvial aquifer system. MODFLOW unstructured-grid was used for modelling groundwater dynamics. A three-dimensional stratigraphic model was developed based on borehole data, and five-layer grid cells were defined according to the material and elevations of the stratigraphic model. Results show that the model reproduces the observed data behaviour very well, including peaks and abrupt declines in the head, as well as the trend of fluctuations in the observation wells. A notable match between the observed and simulated heads indicates the accuracy of the ABC-REJ algorithm based on summary statistics for calibrating and analyzing groundwater models. [ABSTRACT FROM AUTHOR]

The detailed analyses of the water balance components (WBCs) of the catchment help assess the available water resources, especially in the arid climate regions for their sustainable management and development. This paper mainly used the Soil and Water Assessment Tool (SWAT) model to analyze the variation in the WBCs considering the change in the Land Use and Land Cover (LULC) and meteorological variables. For this purpose, the model used the inputs of LULC and meteorological variables between 2001 and 2020 at 5 years and daily time intervals, respectively, from the Chittar river catchment. The developed models were calibrated using SWAT-CUP split-up procedure (pre-calibration and post-calibration). The model was found to be good in calibration and validation, yielding the coefficient of determination (R2) of 0.94 and 0.81, respectively. Furthermore, WBCs of the catchment were estimated for the near future (2021–2030) at the monthly and annual scales. For this endeavor, LULC was forecasted for the years 2021 and 2026 using Cellular Automata (CA)-Artificial Neural Network (ANN), and for the same period, meteorological variables were also forecasted using the smoothing moving average method from the historical data. [ABSTRACT FROM AUTHOR]

Climate change impact started to play significant role since the last three decades almost in every aspects of life especially on meteorological and climatological events and their impacts on water resources, which are managed by engineering structures. Its effects on hydro-meteorological data are assessed by means of available methodologies, but the climate change impact of engineering water structures (dams, culverts, channels, wells, highways and their side drainages, levees, etc.) are not treated equally. This paper provides the review of the necessary adaptation, combat and mitigation activities against the climate change for protection, construction or augmentation of the engineering water structures design capacity. Additionally, land use practices and geomorphological changes also trigger the climate changes on the engineering water structures. The main aim of this paper is to present the impact of such changes on the engineering water structure capacity, operation and maintenance. [ABSTRACT FROM AUTHOR]

Sorghum has been promoted in arid and semi-arid areas due to its drought tolerance which makes it survive under harsh environmental conditions, but grain yields are very low, e.g., averaging 514 kg ha−1. The use of field edge rainwater harvesting techniques of tied contours and infiltration pits can be suitable options to capture rainfall and reduce runoff on the soils. Furthermore, integration of field edge rainwater harvesting with appropriate soil fertility management practices can potentially increase sorghum yields. The use of biomass transfer of nitrogen fixing trees such as Leucaena leucocephala is an agroforestry practice which can improve soil fertility through increasing mineral nitrogen, cation exchange capacity and porosity, water retention, and reduce soil bulk density. Other appropriate soil fertility management include integrated nutrient management (INM) where organic fertilisers such as cattle manure are mixed with inorganic fertilisers. These technologies are examples of climate smart agricultural practices that have the potential to increase sorghum yields. The integration of rainwater harvesting techniques and INM show improved sorghum yields ranging from 750 to 2100 kg ha−1 with potential of increasing yields in clay soils. However, currently there is little data available on the implementation of these technologies in semi-arid areas. This paper reviews and analyses the potential effect of integration rainwater harvesting, biomass transfer and INM on sorghum yields in semi-arid areas of Zimbabwe. [ABSTRACT FROM AUTHOR]

Although it is generally accepted that wetlands in drylands are subject to higher fire frequencies than wetlands in humid regions, little is known about how wetlands in varied hydrogeomorphic settings mediate runoff and material fluxes in the post-fire catchment landscape. This paper evaluates the intermediary role of wetlands in water and sediment dispersal through a wet season that followed the March 2015 wildfire in the Silvermine River catchment, Cape Town. Field and laboratory analyses of the development and dynamics of soil water repellency were conducted across terrestrial hillslope, river riparian zone and hillslope seepage wetland sites. The latter two sites had significantly lower soil water repellency than the terrestrial site immediately preceding the first large rainfall event, and soil moisture emerged as a significant predictor of soil water repellency, consistent with previous research. Remote sensing analysis of post-fire vegetation recovery revealed that the first emergence of new vegetation occurred within wetlands and other moisture-rich areas across the catchment, likely associated with intact rhizome networks of the predominant sprouting vegetation in these areas. This post-fire green flush could have served to enhance post-fire infiltration due to macropore flow along rhizome networks, and to reduce early wet season runoff and erosion due to the rapid establishment of rainfall-intercepting leaf and stem structures. Longitudinal investigations of post-fire river channel and bed sediment characteristics detected a transition in bed composition from gravel to sand through hillslope-channel coupling and channel bank erosion, and effective conveyance of sand through the catchment to a constructed wetland at the catchment outlet. Suspended sediment sampling upstream, within and downstream of this wetland suggested a relative sediment trap efficiency of ~ 87 to 99%, supporting previous observations of post construction aggradation at the head of the wetland, with serious implications for long term wetland maintenance and management. Insights from field and remote sensing studies were used to develop a conceptual geospatial model of the role of wetlands in varied hydrogeomorphic settings in post-fire catchment sediment (dis)connectivity. Hillslope seepage wetlands located across the burned region of the catchment were shown to play an important role in hillslope surface sediment trapping and erosion control, contrary to common assumptions, and sediment connectivity modelling is recommended as a tool for further research aimed at understanding the intermediary role of wetlands in drylands in material fluxes in post-fire landscapes. [ABSTRACT FROM AUTHOR]

Dates are a traditional and important part of the sustainable arid food system. As their popularity is growing worldwide, along with global climate change, there is an increasing need for a better understanding of the environmental aspects of the date production system. Israel is one of the major sources of the Medjool variety of dates. We use an environmental "footprint family" framework to analyze Medjool date production, and direct and indirect environmental interactions, and identify positive and negative hotspots. The research focuses on the Israeli Arava desert region. We found that producing 1 ton of marketable dates has an average material footprint of 1550 kg, a land footprint of 1 m2, and a water footprint of 2450 m3, which leads to 990 kg of solid waste and a carbon footprint of 4820 kg of CO2eq. The cultivation stage was responsible for most of the footprints, mainly due to the direct and indirect consequences of fertilizer usage and water production and intake. The significant differences between the plantations were traced back to their varying mix of palms' age and even more to the human factor and the cultivation methods of individual farmers. We suggest that the environmental footprint of dates can be reduced by adopting improved agricultural methods, such as lower-impact fertilizers and renewable energy. This paper is one of the first to embrace a systematic approach to analyzing dates grown in a desert area. These data can bridge the knowledge gap over the unique food system and crop and, therefore, can provide an initial data body for future research, policy-makers, and farmers as means to advance more efficient, less-intensive use of resources while enhancing production in arid areas and support local and global food security. [ABSTRACT FROM AUTHOR]

Weather and climate conditions drive the evolution of tropical glaciers which play an important role as water reservoirs for Peruvian inhabitants in the arid coast and semi-arid Andean region. The scarcity of long-term high-quality observations over Peruvian glaciers has motivated the extensive use of reanalysis data to describe the climatic evolution of these glaciers. However, the representativeness and uncertainties of these reanalysis products over these glaciers are still poorly constrained. This study evaluates the ability of the ERA5-Land reanalysis (ERA5L) to reproduce hourly and monthly 2 m air temperature and relative humidity (T2m and Rh2m, respectively) over several Peruvian glaciers. We compared the ERA5L with data from four on-glacier automatic weather stations (AWS), whose hourly time series were completed with nearby stations, for the period January 2017 to December 2019. Results indicates a better performance of the reanalysis for T2m (r >0.80) than for Rh2m (∼0.4< r <∼0.6) in all four glaciers. Concerning the observations, both parameters show a daily cycle influenced by the presence of the glacier. This influence is more prominent during the dry months when the so-called glacier damping and cooling effects are stronger. On a monthly time scale, the ERA5L validation for both parameters are better in wet outer tropical sites (RMSE between ±0.2°C for T2m and between 3%–7% for Rh2m) rather than in dry outer tropical sites (RMSE between ±0.2°C for T2m and between 3%–7% for Rh2m). Among all sites considered in the study, the Rh2m bias is the highest in the Cavalca glacier (correlation of 0.81; RMSE 13%, MAE 11% and bias 8.3%) and the lowest in Artesonraju glacier (correlation of 0.96; RMSE 3%; MAE 2.3% and bias — 0.8%). Based on certain considerations outlined in this paper, it is appropriate to use ERA5L to characterize T2m and Rh2m conditions on Peruvian glaciers, particularly in the wet outer tropics. [ABSTRACT FROM AUTHOR]

Water system management is a worldwide challenge, especially in arid and semi-arid regions. Ecological water conveyance projects aim to raise the groundwater table, thereby saving natural vegetation and curbing ecological deterioration. Since 2000, these projects have been implemented in the arid zone of northwest China, with generally successful outcomes. Taking a portion of the lower reaches of the Tarim River as the study area, this paper analyzes in detail the ecohydrological effects which have occurred since the launching of artificial water conveyance 20 years ago. The results show that the groundwater table in the upper, middle and lower segments of the Tarim River's lower reaches has been raised on average 4.06, 4.83 and 5.13 m, respectively, while the area of surface water bodies connected to those sections has expanded from 49.00 km2 to 498.54 km2. At the same time, Taitema Lake, which is the terminal lake of the Tarim River, has been revived and now boasts a water area of 455.27 km2. Other findings indicate that the surface ecological response is extremely sensitive and that the area of natural vegetation has expanded to 1423 km2. Furthermore, the vegetation coverage, vegetation index (NDVI), and Net Primary Productivity (NPP) have increased by 132 km2, 0.07 and 7.6 g C m−2, respectively, and the Simpson dominance, McIntosh evenness, and Margalef richness indices have risen by 0.33, 0.35 and 0.49, respectively, in the monitored sample sites. As well, the carbon sink area has expanded from 1.54% to 7.8%. Given the increasing intensity of the occurrence of extreme hydrological events and successive dry years, similar ecological water conveyance projects should be considered elsewhere in China and in other parts of the world. The water conveyance scheme has generally proven successful and should be optimized to enhance the benefits of ecological water conveyance under water resource constraints. [ABSTRACT FROM AUTHOR]

The paper contributes to the growing literature highlighting the significance of assessing risk and vulnerability, micro-level perceptions and adaptation decision-making in building resilience of farm communities to climate change in dryland region of India. To select a region for grassroots enquiry, spatial differential in risk to climate change was assessed in Rajasthan, using IPCC AR5 framework. Among the highly vulnerable and risky districts, Bikaner district was selected for elicitation of micro-level imperatives. Rising atmospheric temperature, inter-seasonal displacements of rainfall and recurrence of extreme events were perceived by the farmers resulting in resource degradation, production risks and erosion of households' socio-economic dynamics. As risk preventive measures, suitable adjustment in agricultural practices, natural resource management, shift to off-farm activities and other relief measures were adopted by the farmers. Farmer's choice of adaptation was influenced by several climatic, socio-economic and infrastructural & institutional factors in varying degree. Moreover, several financial, economic, infrastructural and informational bottlenecks to adaptations were reported during household survey and FGDs. The results suggest that capturing grassroots evidence is crucial for directing locally tailored adaptation strategies, along with the improving deficiencies in the developmental pathways for climate-resilient agriculture. [ABSTRACT FROM AUTHOR]

The most robust approach to ecological monitoring and assessment is the use of regionally calibrated indicators. These should be calculated based on collocated biological (response) and physicochemical (stressor) variables and an objective rating and scoring system. In developing countries, a frequent lack of financial and technical resources for monitoring has led to many environmental problems being overlooked, such as the degradation of streams, rivers, and watersheds. In this paper, we propose the Karun Macroinvertebrate Tolerance Index (KMTI) for application to rivers in the Karun River basin, which is the largest watershed in Iran, draining semi-arid mountainous regions. The KMTI is the first biological index specifically developed and calibrated for Iranian water resources. Benthic macroinvertebrates, physical habitat, hydromorphic, and water quality data were collected and measured at 54 sites across four seasons in 2018 and 2019. A total of 101 families of benthic macroinvertebrates belonging to eight classes and 21 orders were identified, and tolerance values were determined for 95 families. The KMTI was found to be most efficient in identifying ecological degradation when data were used from winter samples with a discrimination efficiency (DE) 90% and a four-season mean of 84.3%. Also, the best DE of the water quality classification table based on the KMTI index was equal to 86.9%. [ABSTRACT FROM AUTHOR]

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Vertical integration, which creates strategic linkages between national and sub-national levels, is being promoted as important for climate change adaptation. Decentralisation, which transfers authority and responsibility to lower levels of organisation, serves a similar purpose and has been in place for a number of decades. Based on four case studies in semi-arid regions in Africa and India, this paper argues that vertical integration for climate change adaptation should reflect on lessons from decentralisation related to governing natural resources, particularly in the water sector. The paper focuses on participation and flexibility, two central components of climate change adaptation, and considers how decentralisation has enhanced or undermined these. The findings suggest that vertical integration for adaptation will be strengthened if a number of lessons are considered, namely (i) actively seek equitable representation from marginal and diverse local groups drawing on both formal and informal participation structures, (ii) assess and address capacity deficits that undermine flexibility and adaptive responses, especially within lower levels of government, and (iii) use hybrid modes of governance that include government, intermediaries and diverse local actors through both formal and informal institutions to improve bottom-up engagement. [ABSTRACT FROM AUTHOR]