Long-term Water Availability Research Articles

Toward an Integrative Overview of Stygobiotic Crustaceans for Aquifer Delimitation in the Yucatan Peninsula, Mexico

The Yucatan Peninsula (YP) presents heterogeneous environments in a karstic landscape that has been formed from permeable sedimentary rocks dating from the Cretaceous period. Its aquifers now face significant pressure from tourism, agriculture, soil use changes and population growth. Aquifer delimitation typically relies on environmental and socioeconomic criteria, overlooking the subterranean fauna. Stygobiotic crustaceans are highly diverse in the YP’s subterranean karstic systems, expressing adaptations to extreme environments while often also displaying the primitive morphology of evolutionary relics. With distributions restricted to specific environments, they are potential markers of water reserves. A literature review recovered records of 75 species of crustaceans from 132 subterranean systems in the YP, together with geomorphological, hydrological, hydrogeochemical and historical precipitation data. Fourteen UPGMA clusters were informative for mapping species composition, whereby the “Ring of Cenotes”, “Caribbean Cave” and “Cozumel Island” regions were delineated as consolidated aquifers. These aquifers are distinguished by abiotic factors as well: freshwater species dominate the Ring of Cenotes, while marine-affinity species characterize the Caribbean Cave and Cozumel Island aquifers. Stygobiotic crustaceans, being linked to geologically ancient water reserves and having a restricted distribution, offer a complementary tool for aquifer delimitation. Their presence suggests long-term and stable water availability. The use of these unique organisms for integrative aquifer delimitation can provide a way to improve the monitoring networks of regional aquifers.

Климатические изменения годового стока рек Северного Приохотоморья

The aim of this study was to assess the climatic changes in the annual river runoff of the Northern Okhotsk Sea region within the Magadan region. In the present work the analyzed series end with data for 2019. Observation series of river runoff at eight hydrological stations were used in this work. By the method of hydrological analogy, these series were brought to a multiyear period by restoring year-on-year values. Thus, the series of annual runoff for 1958–2019 were analyzed. The research method was the analysis of runoff time series for the presence of homogeneity in the mean (Student’s criterion), as well as spectral analysis. Comparison of mean long-term values of runoff layers for two periods (1958–2000 and 2001–2019) showed that the “norm” increased by 5–37%. It should be noted that these changes are not random according to the Student’s criterion with significance level of 5%. The presence of a trend in long-term water availability fluctuations is also evidenced by the time course of the dynamic mean annual runoff. Analysis of the runoff series, mean annual air temperature and total annual precipitation made it possible to conclude that annual runoff increase is caused by climatic changes, mainly by an increase in precipitation. It is possible that runoff increase is also due to the thawing of ice in the permafrost strata. But you should pay attention to the fact that with climate warming, moisture losses for evapotranspiration increase, primarily due to the growth of trees and shrubs. Moreover, this effect is more noticeable in large catchments. A 6-year cyclicity was revealed in the long-term fluctuations of annual runoff. These fluctuations are most likely a non-stationary complex Markov process. The results of this work will be useful for hydrological calculations, long-term and ultra-long-term runoff forecasts, and studying the river – sea ecosystems. Further hydrological studies should be carried out with the obligatory study of evapotranspiration in various landscape conditions.

Effects of Climate Change on Streamflow in the Godavari Basin Simulated Using a Conceptual Model including CMIP6 Dataset

Hydrological reaction to climate change anticipates water cycle alterations. To ensure long-term water availability and accessibility, it is essential to develop sustainable water management strategies and better hydrological models that can simulate peak flow. These efforts will aid in water resource planning, management, and climate change mitigation. This study develops and compares Sacramento, Australian Water Balance Model (AWBM), TANK, and SIMHYD conceptual models to simulate daily streamflow at Rajegaon station of the Pranhita subbasin in the Godavari basin of India. The study uses daily Indian Meteorological Department (IMD) gridded rainfall and temperature datasets. For 1987–2019, 70% of the models were calibrated and 30% validated. Pearson correlation (CC), Nash Sutcliffe efficiency (NSE), Root mean square error (RMSE), and coefficient of determination (CD) between the observed and simulated streamflow to evaluate model efficacy. The best conceptual (Sacramento) model selected to forecast future streamflow for the SSP126, SSP245, SSP370, and SSP585 scenarios for the near (2021–2040), middle (2041–2070), and far future (2071–2100) using EC-Earth3 data was resampled and bias-corrected using distribution mapping. In the far future, the SSP585 scenario had the most significant relative rainfall change (55.02%) and absolute rise in the annual mean temperature (3.29 °C). In the middle and far future, the 95th percentile of monthly streamflow in the wettest July is anticipated to rise 40.09% to 127.06% and 73.90% to 215.13%. SSP370 and SSP585 scenarios predicted the largest streamflow increases in all three time periods. In the near, middle, and far future, the SSP585 scenario projects yearly relative streamflow changes of 72.49%, 93.80%, and 150.76%. Overall, the findings emphasize the importance of considering the potential impacts of future scenarios on water resources to develop effective and sustainable water management practices.

The last glaciers in Africa and their environmental implications

Climate models and ongoing monitoring studies predict the remaining glaciers in Africa are predicted to disappear by the middle of the 21st Century. These will likely be the only glaciers present on the continent for some tens of thousands of years, until the next global ice age. This paper considers the implications of the shrinking cryosphere in Africa for the surrounding environment and local communities. Glacier retreat will give rise to significant and irreversible downstream effects on East African mountain landscapes in future decades, including impacts on water resources; slope stability and geohazards; ecosystems and ecosystem services; and human socioeconomic and cultural activities and heritage. This foresight study is the first to discuss future environmental impacts of deglacierization in East Africa, and this is framed around understanding the interconnections that exist between physical and human landscape elements in mountainous regions. A key outcome is the identification of elements of mountain systems that are most sensitive to environmental disturbance as a result of global warming, such as long-term water availability and processes that give rise to geohazards, and highlighting the need for management and mitigation of these varied impacts.

How much water did Iran lose over the last two decades?

Study areaIran. Study focusIran, once a pioneer of sustainable water management, is currently facing water bankruptcy. Aggressive exhaustion of non-renewable water has led to a suite of environmental and socio-economic problems across the country. Nevertheless, the understanding of Iran’s water loss is still incomplete due to a lack of conclusive data. In this study, we employ satellite gravimetry observations, in-situ and globally precipitation data, and gauged groundwater level to investigate the total water storage (TWS) loss in Iran over the last two decades. New hydrological insights for the regionWe quantify Iran’s water loss using a data-driven approach supported by a Monte-Carlo simulation. Our analysis indicates TWS loss of 211 ± 34 km3 (> twice Iran’s annual water consumption) within the 2003–2019 period. The mean groundwater level has dropped significantly at a rate of − 28 ± 1.4 cm/yr. This tremendous water loss happened despite an overall increased relative precipitation rate of + 4.9 ± 0.02 km3/yr. Thus the TWS loss can only be explained by drastic overexploitation of non-renewable water resources. Two major extreme events occurred during the study period, namely the 2007 drought and early 2019 floods. The former resulted in a total 115 ± 0.6 km3 water loss, one-third of the long-term annual precipitation. Approximately the same amount was brought back by a series of extreme precipitation events leading to floods in early 2019. Our results raise critical issues regarding unsustainable water management in Iran and highlight the crucial role of spaceborne measurements for understanding short-term and long-term water availability change in the absence of sufficient ground data.

Non-Toxic Increases in Nitrogen Availability Can Improve the Ability of the Soil Lichen Cladonia rangiferina to Cope with Environmental Changes.

Climate change and atmospheric nitrogen (N) deposition on drylands are greatly threatening these especially vulnerable areas. Soil biocrust-forming lichens in drylands can provide early indicators of these disturbances and play a pivotal role, as they contribute to key ecosystem services. In this study, we explored the effects of different long-term water availability regimes simulating climate changes and their interaction with N addition on the physiological response of the soil lichen Cladonia rangiferina. Three sets of this lichen were subjected to control, reduced watering, and reduced watering and N addition (40 kg NH4NO3 ha−1 year−1) treatments for 16 months. Finally, all samples were subjected to daily hydration cycles with N-enriched water at two levels (40 and 80 kg NH4NO3 ha−1 year−1) for 23 days. We found that reduced watering significantly decreased the vitality of this lichen, whereas N addition unexpectedly helped lichens subjected to reduced watering to cope with stress produced by high temperatures. We also found that long-term exposure to N addition contributed to the acclimation to higher N availability. Overall, our data suggest that the interactions between reduced watering and increased N supply and temperature have an important potential to reduce the physiological performance of this soil lichen.

Assessing Variations in Water Use Efficiency and Linkages with Land-Use Changes Using Three Different Data Sources: A Case Study of the Yellow River, China

The dependence of water use efficiency (WUE) on changes in land cover types is crucial for understanding of long-term water availability and assessment of water-saving strategies. Investigating the impact of land cover types on ecosystem WUE has important implications when revealing water dynamics and land management. However, the determination of WUE and its dominant factors have always been subject to high data dependency and large calculation consumption within large basins. This paper proposes a framework for processing actual evapotranspiration (AET) and WUE calculation by coupling the Maximum Entropy Production (MEP) method with the Google Earth Engine (GEE). By employing the proposed framework and three data sources available in the GEE platform, results for actual ET and WUE from 2001 to 2020 were obtained in the Yellow River Basin (YRB). The results show that the proposed framework provides an acceptable estimation of actual ET via validation with Eddy Covariance flux sites in the YRB. The calculated WUE values varied greatly in different sub-basins within the YRB, indicating a cumulative growth rate of about 56% during the past 20 years. The dominant factor that led to these changes was the transition from Grasslands into other land-use types. Our results suggest that the use of the GEE platform coupled with the MEP method offers new possibilities for advancing understanding of water exchange and water resource management.

Leaf trait modification in European beech trees in response to climatic and edaphic drought.

Leaf morphological and physiological traits control the carbon and water relations of mature trees and are determinants of drought tolerance, but it is not well understood how they are modified in response to water deficits. We analysed five sun-canopy leaf traits (mean leaf size (LS), specific leaf area (SLA), Huber value (HV), water potential at turgor loss point (Ψtlp ) and foliar carbon isotope signature (δ13 C)) in European beech (Fagus sylvatica L.) across three precipitation gradients sampled in moist (2010), dry (2019) and very dry (2018) summers, and tested their response to short-term water deficits (climatic water balance (CWB) preceding sample collection) and long-term water availability (mean annual precipitation (MAP), plant-available soil water capacity (AWC) and neighbourhood competition). Across the 34 sites, LS varied seven-fold (3.9-27.0 cm2 ), SLA four-fold (77.1-306.9 cm²·g-1 ) and HV six-fold (1.0-6.65 cm2 ·m-2 ). In the 2018 dataset, LS showed a negative and HV a positive relationship to MAP, which contradicts relations found in multi-species samples. Average Ψtlp ranged from -1.90 to -2.62 MPa and decreased across the sites with decreasing CWB in the month prior to measurement, as well as with decreasing MAP and AWC in 2019. Studied leaf traits varied considerably between years, suggesting that mast fruiting and the severe 2018 drought caused the formation of smaller leaves. We conclude that sun-canopy leaf traits of European beech exhibit considerable plasticity in response to climatic and edaphic aridity, and that osmotic adjustment may be an important element in the drought response strategy of this anisohydric tree species.

A hydro-climatological outlook on the long-term availability of water resources in Cauvery river basin

The past few decades have witnessed massive shifts in land-use patterns, land management practices and water demand in the river basins of peninsular India. Changes in hydrologic regimes of different components of the water cycle pose immense challenge to water security at the catchment scale. This paper provides a comprehensive overview and a quantitative assessment of the long-term availability of water resources in the Cauvery river basin, a major river basin in peninsular India. The Cauvery has been a contentious river for decades regarding water sharing among its riparian states of Karnataka and Tamil Nadu. Moreover, the river basin is characterized by extensive regional variability in both surface water and groundwater distributions and has faced acute water management challenges at multiple space and time scales. A descriptive overview of the major water security challenges faced by the basin is presented along with a detailed synthesis of hydrological modelling approaches and statistical methods to assess the basin’s long-term water availability. The Variable Infiltration Capacity (VIC) model is implemented to evaluate the long-term water balance components at the catchment scale for the period 1951–2016. Decadal Land Use Land Cover (LULC) in the basin for the years 1985, 1995 and 2005 are analysed. The statistical trends in hydrometeorology and extreme climatology of the basin are evaluated at seasonal and annual scales. Seasonal flow behaviour and influence of climate and human activities on streamflow are also assessed. A drought duration analysis is performed to infer about the implications of spatial distribution of water availability across the basin. The results show significant trends in the water balance components and the basin’s hydro-climatology. The LULC analysis shows notable changes in land use patterns due to human activities. Alterations in the predictability and temporal variability of streamflow are observed after the construction of dams which may affect the downstream water availability. This research highlights the importance of comprehensive synthesis of hydrological modelling approaches with hydrological signatures to understand the dynamics of hydrological processes at catchment scale with an objective of providing insights for effective planning and allocation of water resources and judicious management of water demands.

Drivers and extent of surface water occurrence in the Selenga River Delta, Russia

Study regionSelenga River Delta (SRD), Russia. Study focusHow is water occurrence changing in the SRD, and what are the hydroclimatic drivers behind these changes? The presence of water on the surface in river deltas is governed by land use, geomorphology, and the flux of water to and from the Delta. We trained an accurate image classification of the Landsat satellite imagery during the last 33 years to quantify surface water occurrence and its changes in the SRD. After comparing our estimations with global-scale datasets, we determined the hydrological drivers of these changes. New hydrological insights for the regionWe find mild decreases in water occurrence in 51% of the SRD's surface area from 1987–2002 to 2003–2020. Water occurrence in the most affected areas decreased by 20% and in the most water-gaining areas increased by 10%. We find a significant relationship between water occurrence and runoff (R2 =0.56) that does not exist between water occurrence and suspended sediment concentration (SSC), Lake Baikal's water level, and potential evapotranspiration. The time series of water occurrence follows the peaks in the runoff but not its long-term trend. However, the extremes in SSC do not influence surface water occurrence (R2 <0.1), although their long-term trends are similar. Contrary to expected, we find that the Delta has a relatively stable long-term water availability for the time being.

Spatial variability in tree-ring carbon isotope discrimination in response to local drought across the entire loblolly pine natural range

Considering the temporal responses of carbon isotope discrimination (Δ13C) to local water availability in the spatial analysis of Δ13C is essential for evaluating the contribution of environmental and genetic facets of plant Δ13C. Using tree-ring Δ13C from years with contrasting water availability at 76 locations across the natural range of loblolly pine, we decomposed site-level Δ13C signals to maximum Δ13C in well-watered conditions (Δ13Cmax) and isotopic drought sensitivity (m) as a change in Δ13C per unit change of Palmer's Drought Severity Index (PDSI). Site water status, especially the tree lifetime average PDSI, was the primary factor affecting Δ13Cmax. The strong spatial correlation exhibited by m was related to both genetic and environmental factors. The long-term average water availability during the period relevant to trees as indicated by lifetime average PDSI correlated with Δ13Cmax, suggesting acclimation in tree gas-exchange traits, independent of incident water availability. The positive correlation between lifetime average PDSI and m indicated that loblolly pines were more sensitive to drought at mesic than xeric sites. The m was found to relate to a plant's stomatal control and may be employed as a genetic indicator of efficient water use strategies. Partitioning Δ13C to Δ13Cmax and m provided a new angle for understanding sources of variation in plant Δ13C, with several fundamental and applied implications.

Hydrological Modeling of Green Infrastructure to Quantify Its Effect on Flood Mitigation and Water Availability in the High School Watershed in Tucson, AZ

Green Infrastructure (GI) practices are being implemented in numerous cities to tackle stormwater management issues and achieve co-benefits such as mitigating heat island effects and air pollution, as well as water augmentation, health, and economic benefits. Tucson, Arizona is a fast-growing city in the semiarid region of the southwest United States and provides a unique landscape in terms of urban hydrology and stormwater management, where stormwater is routed along the streets to the nearest ephemeral washes. Local organizations have implemented various GI practices, such as curb cuts, traffic chicanes, roof runoff harvesting, and retention basins, to capture the excess runoff and utilize it on-site. This study models the 3.31 km2 High School watershed in central Tucson using the Automated Geospatial Watershed Assessment (AGWA) tool and the Kinematic Runoff and Erosion (KINEROS2) model. Each parcel in the watershed was individually represented using the KINEROS2 Urban element to simulate small-scale flow-on/flow-off processes. Seven different configurations of GI implementation were simulated using design storms, and we stochastically generated 20 years of precipitation data to understand the effects of GI implementation on flood mitigation and long-term water availability, respectively. The design storm analysis indicates that the configuration designed to mimic the current level of GI implementation, which includes 175 on-street basins and 37 roof runoff harvesting cisterns, has minimum (&lt;2%) influence on runoff volume. Furthermore, the analysis showed that the current level of GI implementation caused an increase (&lt;1%) in peak flows at the watershed outlet but predicted reduced on-street accumulated volumes (&gt;25%) and increased water availability via GI capture and infiltration. When the GI implementation was increased by a factor of two and five, a larger reduction of peak flow (&lt;8% and &lt;22%, respectively) and volume (&lt;3% and &lt;8%, respectively) was simulated at the watershed outlet. The 20-year analysis showed that parcels with roof runoff harvesting cisterns were able to meet their landscape irrigation demands throughout the year, except for the dry months of May and June. Additionally, stormwater captured and infiltrated by the on-street basins could support xeric vegetation for most of the year, except June, where the water demand exceeded volume of water infiltrated in the basins. The current level of GI implementation in the High School watershed may not have significant large-scale impacts, but it provides numerous benefits at the parcel, street, and small neighborhood scales.

Long-term climatic water availability trends and variability across the African continent

Long-term climatic water availability trends and variability across the African continent

Quantitative contributions of climate change and human activities to vegetation changes over multiple time scales on the Loess Plateau

Vegetation is a crucial component of terrestrial ecosystems, and its changes are driven mainly by a combination of climate change and human activities. This paper aims to reveal the relationship between vegetation and climate change by using the normalized difference vegetation index (NDVI) and standardized precipitation evapotranspiration index (SPEI), and to find the cause of vegetation change by performing residual analysis on the Loess Plateau during the period from 2000 to 2016. The results showed that the NDVI on the Loess Plateau exhibited an increase of 0.086 per decade, and an increasing trend was observed across 94.86% of the total area. The relationship between the NDVI and SPEI was mainly positive, and the correlation increased as the time scale of the SPEI lengthened, indicating that long-term water availability was the major climate factor affecting vegetation growth. Residual analysis indicated that climate change was responsible for 45.78% of NDVI variation, while human activities were responsible for 54.22%. In areas with degraded vegetation, the relative roles of climate change and human activities were 28.11% and 72.89%, respectively. In addition, the relative role of climate change increased with an increase in the time scales, implying that the long-term NDVI trend was more sensitive to climate change then the short-term trend. The results of this study are expected to enhance our understanding of vegetation changes under climate change and human activities and provide a scientific basis for future ecological restoration in arid regions.

Watershed based model for water allocation

The city of Bekasi is located downstream of the Bekasi watershed, which currently cannot reach the target of access to clean water. Access to clean water in Bekasi City according to USAID (2017) only reaches 31.44%, thus it has not yet reached the target of Sustainable Development Goals (SDGs). Moreover, many upstream areas of the watershed have been grown as a satellite city that plans to harvest more water to meet their needs. And also urban and rural areas in the whole watershed have population growth that needs a water supply. Increasing water demand due to population in upstream and downstream areas can cause water conflicts if not managed wisely. A water allocation study by making a model of the Bekasi watershed could explain better water allocation solution. This study’s purpose is to make a model for meeting the raw water demand of both urban and rural areas within Bekasi watershed. The more allocation of water in the upstream part of the Bekasi watershed (Sentul City) shows a decrease in the long-term water availability of water supply in the downstream watershed (Bekasi City). The development area of the upper part of Bekasi watershed should be evaluated properly and policy settings for water allocation can be analyzed using the dynamic model built.

Elevated CO2 Did Not Stimulate Stem Growth in 11 Provenances of a Globally Important Hardwood Plantation Species

Elevated atmospheric carbon dioxide (eCO2) often enhances rates of photosynthesis leading to increased productivity in trees. In their native habitats in Australia, eucalypts display considerable phenotypic plasticity in response to changes in environmental conditions. Little is known whether this plasticity can be harnessed effectively under future atmospheric eCO2 conditions and be used to identify provenances with superior growth. Here, we report two experiments that assessed the physiological and growth responses of Eucalyptus grandis – one of the world’s most important hardwood plantation species – to eCO2. We used 11 provenances from contrasting climates. Our selection was based on site-specific information of long-term temperature and water availability. In Experiment 1, four provenances exhibited significant variation in light-saturated photosynthetic rates (Asat), stomatal conductance (gs) and concentrations of non-structural carbohydrates in leaves, stems and roots when grown under ambient CO2 (aCO2). Biomass of leaves, stems and roots varied significantly and were negatively correlated with mean annual temperature (MAT) at seed origin, indicating that provenances from cooler, wetter climates generally produced greater biomass. Yet, stem growth of these provenances was not stimulated by eCO2. Given the vast environmental gradient covered by provenances of E. grandis, we expanded the selection from four to nine provenances in Experiment 2. This allowed us to validate results from Experiment 1 with its small selection and detailed measurements of various physiological parameters by focusing on growth responses to eCO2 across a wider environmental gradient in Experiment 2. In Experiment 2, nine provenances also exhibited intraspecific differences in growth, but these were not related to climate of origin, and eCO2 had little effect on growth traits. Growth responses under eCO2 varied widely across provenances in both experiments, confirming phenotypic plasticity in E. grandis, though responses were not systematically correlated with climate of origin. These results indicate that selection of provenances for improved stem growth of E. grandis under future eCO2 cannot be based solely on climate of origin, as is common practice for other planted tree species.

Leaf trait variation is similar among genotypes of Eucalyptus camaldulensis from differing climates and arises in plastic responses to the seasons rather than water availability.

We used a widely distributed tree Eucalyptus camaldulensis subsp. camaldulensis to partition intraspecific variation in leaf functional traits to genotypic variation and phenotypic plasticity. We examined if genotypic variation is related to the climate of genotype provenance and whether phenotypic plasticity maintains performance in a changing environment. Ten genotypes from different climates were grown in a common garden under watering treatments reproducing the wettest and driest edges of the subspecies' distribution. We measured functional traits reflecting leaf metabolism and associated with growth (respiration rate, nitrogen and phosphorus concentrations, and leaf mass per area) and performance proxies (aboveground biomass and growth rate) each season over a year. Genotypic variation contributed substantially to the variation in aboveground biomass but much less in growth rate and leaf traits. Phenotypic plasticity was a large source of the variation in leaf traits and performance proxies and was greater among sampling dates than between watering treatments. The variation in leaf traits was weakly correlated to performance proxies, and both were unrelated to the climate of genotype provenance. Intraspecific variation in leaf traits arises similarly among genotypes in response to seasonal environmental variation, instead of long-term water availability or climate of genotype provenance.

Twenty-First Century Streamflow and Climate Change in Forest Catchments of the Central Appalachian Mountains Region, US

Forested catchments are critical sources of freshwater used by society, but anthropogenic climate change can alter the amount of precipitation partitioned into streamflow and evapotranspiration, threatening their role as reliable fresh water sources. One such region in the eastern US is the heavily forested central Appalachian Mountains region that provides fresh water to local and downstream metropolitan areas. Despite the hydrological importance of this region, the sensitivity of forested catchments to climate change and the implications for long-term water balance partitioning are largely unknown. We used long-term historic (1950–2004) and future (2005–2099) ensemble climate and water balance data and a simple energy–water balance model to quantify streamflow sensitivity and project future streamflow changes for 29 forested catchments under two future Relative Concentration Pathways. We found that streamflow is expected to increase under the low-emission pathway and decrease under the high-emission pathway. Furthermore, despite the greater sensitivity of streamflow to precipitation, larger increases in atmospheric demand offset increases in precipitation-induced streamflow, resulting in moderate changes in long-term water availability in the future. Catchment-scale results are summarized across basins and the region to provide water managers and decision makers with information about climate change at scales relevant to decision making.

Temporal trend of drought and aridity indices in semi-arid pernambucano to determine susceptibility to desertification

ABSTRACT In semi-arid regions, the use of drought and aridity indices in order to establish diagnoses and prognoses that help in water resources management is crucial, above all, for the evaluation of long-term water availability, and monitoring hydrological extreme events. Therefore, the aim of this study was to evaluate the trends of extreme events to determine susceptibility to desertification in the Brígida river basin, by Drought (RAI, SPI and PDSI) and Aridity (MIA, AI and AIASD) Indices. The results of these indices submitted to statistical analysis (Tukey Test) and to the evaluation of the climate trend (TREND software). The Tukey Test indicated that the PDSI and RAI method are the most suitable for drought analysis, while AI is most appropriate for aridity. The results indicated that regardless of the indices employed, the stations presented significant results in the trend analysis, suggesting intensification of these events over time. Therefore, concluded that drought and aridity indices could help water resources management by managing bodies, indicating the evolution of extreme hydrological phenomena, suggesting the adoption of preventive and mitigating actions regarding the use of water priority. In conclusion, these indices can be used as a tool for indicating areas susceptible to the desertification process.

Decentralized water collection systems for households and communities: Household preferences in Atlanta and Boston

Development of sustainable and resilient water infrastructure is an urgent challenge for urban areas to secure long-term water availability and mitigate negative impacts of water consumption and urban development. A hybrid system that combines centralized water infrastructure and household decentralized water facilities, including rainwater harvesting and greywater recycling, may be a solution to more sustainable and resilient water management in urban areas. Understanding household and community preferences for decentralized water facilities is important to inform the design and ultimately the promotion and adoption of such systems. In this study, we conducted a discrete choice experiment, via Amazon Mechanical Turk, to collect data on household choices of different decentralized water facility designs in two U.S. cities, Atlanta, Georgia and Boston, Massachusetts. Based on the responses to the choice experiment, we then developed a latent-class choice model to predict households’ preferences of decentralized system design features and examine the influence of socioeconomic and personal characteristics on heterogeneous class membership. We identified six major classes of preferences in Atlanta and Boston, respectively, and evaluated how readily each class is likely to choose a decentralized water facility. Atlanta and Boston have some classes sharing similar preferences for decentralized water systems, but the socioeconomic and personal characteristics of these classes in the two cities are different. We found that the early adoption of decentralized water facilities is positively related to neighbors’ adoptions and pressure of water scarcity increases households’ willingness to share a decentralized facility. The visualization of spatial distribution of the classes highlighted early demand of decentralized water facilities is likely to emerge in low-property-value communities, which creates a unique opportunity for introducing decentralized water facilities during water infrastructure renovations. Our study provides a framework through citizen engagement to understand social demand and to inform the promotion of decentralized water facilities.