Patterns Of Water Availability Research Articles

Seasonal and vertical patterns of water availability and variability determine plant reproductive phenology.

Changing precipitation regimes can influence terrestrial plants and ecosystems. However, plant phenological responses to changing precipitation temporal patterns and the underlying mechanisms are largely unclear. This study was conducted to explore the effects of seasonal precipitation redistribution on plant reproductive phenology in a temperate steppe. A field experiment with control (C), advanced (AP) and delayed (DP) growing-season precipitation peaks, and the combination of AP and DP (ADP) were employed. Seven dominant plant species were selected and divided into two functional groups (early- vs. middle-flowering species, shallow- vs. deep-rooted species) to monitor reproductive phenology including budding, flowering, and fruiting date, as well as reproductive duration for four growing seasons from 2015 to 2017, and 2022. The AP, but not DP treatment advanced the phenological (i.e., budding, flowering, and fruiting) dates and lengthened the reproductive duration across the 4 growing seasons and 7 monitored species. In addition, the phenological responses showed divergent patterns among different plant functional groups, which could be attributed to shifts in soil moisture and its variability in different months and soil depths. Moreover, species with lengthened reproductive duration increased phenological overlap with other species, which could have a negative impact on their dominance under the AP treatment. Our findings reveal that changing precipitation seasonality could have considerable impacts on plant phenology by affecting soil water availability and variability. Incorporating these two factors simultaneously in the phenology models will help us understand the response of plant phenology under intensified changing precipitation scenarios. In addition, the observations of decreased dominance for the species with lengthened reproductive duration suggest that changing reproductive phenology can have a potential to affect community composition in grasslands under global change.

Expect the unexpected: a new species of killifish from a highly stochastic temporary wetland near Iguazú Falls (Cyprinodontiformes: Rivulidae)

We describe Argolebias adrianae, a new species of killifish from a small temporary wetland in the Paraná Forest ecoregion with no regular or predictable temporal pattern of water availability. This habitat is in the Lower Iguazú River Basin, known for its high fish endemism, but until now, only two species of Rivulidae were reported from it, but from the Araucarian Forest ecoregion. The genus Argolebias was previously only known from the lower portions of the Paraguay, Paraná, and Uruguay basins and middle Paraná. The new species is distinguished from all congeners by its unique coloration, which includes a conspicuously dark grey anterior third portion of the dorsal fin and the absence of iridescent spots on the basal half of the pectoral fin in live adult males, as well as dark grey spots on the anterocentral portion of the flanks of females. Our phylogenetic analysis shows A. adrianae to be closely related to Argolebias guarani from the adjacent Middle Paraná basin. We also provide data on the ecology, ontogeny of coloration, and chorion ornamentation of this species. Our findings have important implications for understanding the biogeography, ecology, and evolution of mechanisms that enable organisms to thrive in highly stochastic environments like this one.

Exploring climatic variability and drought characteristics in Morocco’s Sais Plateau and Middle Atlas: A statistical and spectral analysis

Extreme climate change phenomena are a global reality with major repercussions on hydrosystems. Drought is particularly concerning in the southern Mediterranean region, threatening water availability and related behavior. Morocco, located in North Africa and the southern Mediterranean, is highly exposed to climate change and its consequences, particularly drought. This study aims to investigate the impact of climate variability and drought characteristics on the Saïs plateau and the Middle Atlas region, using statistical and spectral indices. By analyzing annual variations in precipitation and using the Standardized Precipitation Index (SPI) and normalized difference water index (NDWI) to elucidate the temporal dynamics of water, this study highlights significant irregularities in precipitation patterns between wet and dry years, offering insight into the severity and occurrence of drought at different altitudes. In addition, the study uses the normalized difference water index (NDWI) to elucidate temporal water dynamics, revealing cyclical patterns of water availability and identifying regions sensitive to hydrological activity or drought. Furthermore, thanks to a correlation analysis between the NDWI and the SPI12 index, the study highlights the complementary relationship between spectral and statistical indices in the assessment of drought phenomena. The results show a significant difference in precipitation between the Middle Atlas and the Sais Plateau, with the Middle Atlas receiving around double the precipitation. From 1980 to 1985, drought was followed by even drier conditions until 1995, with sporadic wet years such as 1995 and 2002. During the 1980–1994 period, a persistent drought was observed until 1995, when precipitation picked up again, with notable records in 2009–2010. Positive NDWI values, with marked peaks between 2010 and 2012, indicate periods of high-water content, while negative values, such as those in 1995, 2003, and 2006, denote periods of low water content or drought.

Cascade effects of climate and vegetation influencing the spatial variation of evapotranspiration in China

Evapotranspiration (ET) is generally affected by climate and vegetation, but the main factor controlling the spatial variation of ET largely varied with different regions. Clarifying the characteristics and dominant factor of ET in China is essential for understanding the regional ecosystem water balance. This study quantitatively assessed the magnitude and spatial variations of ET in China's terrestrial ecosystems using data measured by eddy covariance from 150 observation sites and investigated its underlying direct and indirect influencing factors. The results demonstrated that the ET of China's terrestrial ecosystems varied from 146.95 to 1125.33 mm, with an average value of 551.00 ± 204.12 mm. The ET showed a general increasing trend from the North to South, aligning with the latitudinal patterns of water availability (mean annual precipitation (MAP)), energy conditions (mean annual net radiation (MARn), and mean annual temperature (MAT)). Compared to regions at the same latitude, the North China Plain exhibited relatively higher ET because of the extensive cropland sites in the area. Furthermore, significant positive linear correlations were found between ET and MAT in the majority of ecosystems. However, a negative correlation of ET with MAT was observed in grasslands, which may be attributed to inconsistent responses of ET to MAT on the Tibetan Plateau and Inner Mongolia. Fractional vegetation coverage (FVC) exhibited a more significant direct influence on ET than climate factors (MARn, MAT, and MAP). Nevertheless, climate factors not only exert a direct influence on ET but also have cascade effects that affect FVC, thereby indirectly influencing the ET. When considering these cascade effects, MAP emerged as the dominant driver of spatial variations in ET of China's terrestrial ecosystems. This study provides essential information on variations of ET in China's terrestrial ecosystem and valuable insights for future explorations into the adaptive mechanisms underlying spatial variations of ET.

Site matters - Canopy conductance regulation in mature temperate trees diverges at two sites with contrasting soil water availability

Tree-specific canopy conductance (Gc) and its adjustment play a critical role in mitigating excess water loss in changing environmental conditions. However, the change of Gc sensitivity to environmental conditions due to drought remains unclear for European tree species. Here we quantified the environmental operational space of Gc, i.e., the water supply (soil moisture, tree water deficit) and demand conditions (vapor pressure deficit) under which Gc ≥ 50% is possible (Gc50OS), at two sites with different soil water availability for three common European tree species. We collected sap flow and dendrometer measurements for co-occurring Pinus sylvestris, Fagus sylvatica and Quercus petraea growing under different soil hydrological conditions (drier/wetter). These measurements were combined with meteorological variables and soil moisture conditions in five depths. Dendrometer measurements were used to confirm soil water availability patterns. For all analyses, the contrasting soil hydrology between sites was the main driver of Gc response. At the drier sites, F. sylvatica and P. sylvestris reduced their water consumption in response to decreasing soil water supply earlier in the growing season than Q. petraea. However, our analysis on the Gc50OS revealed that at the drier sites, F. sylvatica and Q. petraea reduced the extent of their Gc50OS to a higher degree than P. sylvestris. This indicates a higher level of Gc50OS adjustment to the drier site conditions for the two broadleaved species. These differences were more pronounced when using the dendrometer-derived tree internal water status as proxy for tree water supply. Our results provide preliminary evidence for diverging short-term Gc responses when temperate trees are exposed to prolonged reduction in water availability. These findings suggest that Gc50OS can help to constrain species-specific predictions of water use by mature trees, especially when combined with high-resolution water potential measurements.

Unique drought resistance strategies occur among monkeyflower populations spanning an aridity gradient.

Annual plants often exhibit drought-escape and avoidance strategies to cope with limited water availability. Determining the extent of variation and factors underlying the evolution of divergent strategies is necessary for determining population responses to more frequent and severe droughts. We leveraged five Mimulus guttatus populations collected across an aridity gradient within manipulative drought and quantitative genetics experiments to examine constitutive and terminal-drought induced responses in drought resistance traits. Populations varied considerably in drought-escape- and drought-avoidance-associated traits. The most mesic population demonstrated a unique resource conservative strategy. Xeric populations exhibited extreme plasticity when exposed to terminal drought that included flowering earlier at shorter heights, increasing water-use efficiency, and shifting C:N ratios. However, plasticity responses also differed between populations, with two populations slowing growth rates and flowering at earlier nodes and another population increasing growth rate. While nearly all traits were heritable, phenotypic correlations differed substantially between treatments and often, populations. Our results suggest drought resistance strategies of populations may be finely adapted to local patterns of water availability. Substantial plastic responses suggest that xeric populations can already acclimate to drought through plasticity, but populations not frequently exposed to drought may be more vulnerable.

Environmental degradation of vegetation cover and water bodies in the semiarid region of the Brazilian Northeast via cloud geoprocessing techniques applied to orbital data

The spatiotemporal diagnosis of climate variability and environmental changes in arid and semiarid regions is essential to minimize pressures and impacts on natural ecosystems. Remote sensing techniques and satellite images allow the detection of such changes. The study evaluated spatio-temporally the processes of environmental degradation of vegetation cover and water resources via physical-hydric parameters at the surface using remote sensing techniques for the Northeast of Brazil (NEB). Geospatial data from TRMM and MODIS satellites/sensors, digital cloud processing of vegetation indices (NDVI), water (NDWI and MNDWI), and rainfall were performed for the period 2000 to 2019. The patterns identified in the study were evaluated by multivariate statistics and correlation. The NDVI showed the significant vulnerability of vegetation cover in the Northeastern Semiarid region, due to the intensification of droughts. The spectral behavior of NDVI is due to rainfall, confirmed by principal component analysis (PCA) and correlation. The NDWI and MNDWI detected the pattern of water availability in the semiarid region, with a critical reduction in water bodies. In the space-time analysis, the physical-hydric parameters showed a significant water deficit, followed by severe drought and prolonged drought. MNDWI was efficient and sensitive to open water content, especially in areas covered by water bodies concerning NDWI, and correlated with rainfall. The variability of rainfall directly impacted the dynamics and resilience of vegetation and water bodies in the Northeastern Semiarid region. The critical reduction of areas of water bodies, the increase of non-vegetated areas, and the pressures of anthropic activities are favored.

Climatic Asynchrony and Hydrologic Inefficiency Explain the Global Pattern of Water Availability

AbstractThe mechanisms underlying observed global patterns of partitioning precipitation () to evapotranspiration () and runoff () are controversially debated. We test the hypothesis that asynchrony between climatic water supply and demand is sufficient to explain spatio‐temporal variability of water availability. We developed a simple analytical model for that is determined by four dimensionless characteristics of intra‐annual water supply and demand asynchrony. The analytical model, populated with gridded climate data, accurately predicted global runoff patterns within 2%–4% of independent estimates from global climate models, with spatial patterns closely correlated to observations (). The supply‐demand asynchrony hypothesis provides a physically based explanation for variability of water availability using easily measurable characteristics of climate. The model revealed widespread responsiveness of water budgets to changes in climate asynchrony in almost every global region. Furthermore, the analytical model using global averages independently reproduced the Budyko curve () providing theoretical foundation for this widely used empirical relationship.

Cost-benefit of green infrastructures for water management: A sustainability assessment of full-scale constructed wetlands in Northern and Southern Italy

Sustainable water management has become an urgent challenge due to irregular water availability patterns and water quality issues. The effect of climate change exacerbates this phenomenon in water-scarce areas, such as the Mediterranean region, stimulating the implementation of solutions aiming to mitigate or improve environmental, social, and economic conditions. A novel solution inspired by nature, technology-oriented, explored in the past years, is constructed wetlands. Commonly applied for different types of wastewater due to its low cost and simple maintenance, they are considered a promising solution to remove pollutants while creating an improved ecosystem by increasing biodiversity around them. This research aims to assess the sustainability of two typologies of constructed wetlands in two Italian areas: Sicily, with a vertical subsurface flow constructed wetland, and Emilia Romagna, with a surface flow constructed wetland. The assessment is performed by applying a cost-benefit analysis combining primary and secondary data sources. The analysis considered the market and non-market values in both proposed scenarios to establish the feasibility of the two options and identify the most convenient one. Results show that both constructed wetlands bring more benefits (benefits-cost ratio, BCR) than costs (BCR > 0). In the case of Sicily, the BCR is lower (1) in the constructed wetland scenario, while in its absence it is almost double. If other ecosystem services are included the constructed wetland scenario reach a BCR of 4 and a ROI of 5, showing a better performance from a costing perspective than the absence one. In Emilia Romagna, the constructed wetland scenario shows a high BCR (10) and ROI (9), while the scenario in absence has obtained a negative present value indicating that the cost do not cover the benefits expected. Further research should be focused on improving ecosystem services monetary quantification from different context (i.e. rural vs urban).

Quantifying the effect of vegetation greening on evapotranspiration and its components on the Loess Plateau

As one of the largest revegetation projects in China, the Grain for Green Project has dramatically increased vegetation greenness (greening) on the Loess Plateau. Large-scale greening inevitably changed the spatiotemporal pattern of water availability on the Loess Plateau by increasing evapotranspiration (ET). Quantifying the effect of greening on ET is critical for regional water resources management and planning. This study uses the maximum entropy production (MEP) model and two attribution methods (the detrending and extending methods) to quantify the effect of greening on ET and its components (soil evaporation (Es) and transpiration (Et)) on the Loess Plateau from 2001 to 2018. The ensemble-averaged results of two attribution methods are used to reduce the potential uncertainty caused by the choice of attribution methods. The MEP model performs well in capturing the spatiotemporal variability of ET on both the site and basin scales. Greening significantly (p < 0.05) increases Et and decreases Es for the Loess Plateau, and the magnitude of increase in Et exceeds the magnitude of decrease in Es, leading to a nonsignificant (p > 0.05) increase in ET. The contribution of greening to mean annual Es, Et, and ET for the Loess Plateau is −16.6, 20.7, and 4.1 mm/yr, respectively. An increase in ET may further exacerbate water scarcity for the Loess Plateau.

A conceptual framework for gender and climate mainstreaming to mitigate water inaccessibility in ruralsub‐SaharanAfrica

AbstractEvidence underscores that water inaccessibility in rural sub‐Saharan Africa (SSA) disproportionately affects women due to patriarchal gender norms and practices. In the context of Sustainable Development Goals 5 (Gender Equality) and 6 (Water and Sanitation), globally driven efforts and initiatives are set against a backdrop of empowering women, improving rural water accessibility, and reducing water‐related risks. Furthermore, climate change is altering spatiotemporal patterns of water availability and quality. A thematic analysis of the literature was conducted through Scopus and Web of Science to identify drivers and consequences of as well as coping strategies for water (in)accessibility in rural SSA. A conceptual framework was developed to better understand and assess research gaps and points of intervention for gender and climate mainstreaming in mitigation strategies that reduce the impacts of water inaccessibility in rural SSA. Findings show that complex intersecting factors underlie water inaccessibility—and responses—among rural women in SSA. The complex socio‐ecological interlinkages among climate change, water, and gender are discussed and a case is made for more integrative research (including dimensions of vulnerability, impacts, and effective grassroots strategies and co‐benefits) to inform policy, planning, and practice.This article is categorized under:Engineering Water &gt; Water, Health, and SanitationScience of Water &gt; Water and Environmental ChangeHuman Water &gt; Rights to Water

The other side of tropical forest drought: do shallow water table regions of Amazonia act as large-scale hydrological refugia from drought?

Tropical forest function is of global significance to climate change responses, and critically determined by water availability patterns. Groundwater is tightly related to soil water through the water table depth (WT), but historically neglected in ecological studies. Shallow WT forests (WT < 5 m) are underrepresented in forest research networks and absent in eddy flux measurements, although they represent c. 50% of the Amazon and are expected to respond differently to global-change-related droughts. We review WT patterns and consequences for plants, emerging results, and advance a conceptual model integrating environment and trait distributions to predict climate change effects. Shallow WT forests have a distinct species composition, with more resource-acquisitive and hydrologically vulnerable trees, shorter canopies and lower biomass than deep WT forests. During 'normal' climatic years, shallow WT forests have higher mortality and lower productivity than deep WT forests, but during moderate droughts mortality is buffered and productivity increases. However, during severe drought, shallow WT forests may be more sensitive due to shallow roots and drought-intolerant traits. Our evidence supports the hypothesis of neglected shallow WT forests being resilient to moderate drought, challenging the prevailing view of widespread negative effects of climate change on Amazonian forests that ignores WT gradients, but predicts they could collapse under very strong droughts.

Shifting seasonal patterns of water availability: ecosystem responses to an unappreciated dimension of climate change.

Seasonal patterns of water availability can differ dramatically among ecosystems, with well-known consequences for ecosystem structure and functioning. Less appreciated is that climate change can shift the seasonality of water availability (e.g. to wetter springs, drier summers), resulting in both subtle and profound ecological impacts. Here we (1) review evidence that the seasonal availability of water is being altered in ecosystems worldwide, (2) explore several mechanisms potentially driving these changes, and (3) highlight the breadth of ecological consequences resulting from shifts in the seasonality of water availability. We conclude that seasonal patterns of water availability are changing globally, but in regionally specific ways requiring more rigorous and nuanced assessments of ecosystem vulnerability as well as the ecological consequences.

Temporal variabilities and correlation of runoff in the Ural River

The article deals with the study of intra-annual discharge distribution of the Ural River basin runoff. Norms, coefficients of variation, and average standard deviations of monthly, seasonal and annual runoff, as well as maximum and minimum flow and the tendencies of its changes, were determined for rivers in the area. The average and maximum water discharge spring high water and the ratio of maximum and minimum monthly and the annual runoff were calculated. Based on the wavelet transform method applied to the river flow data of the area under study, a cyclical pattern of water availability was identified. Moreover, the closeness of the correlation between average monthly expenditures and annual average water consumption, as well as the average monthly water costs was revealed. The statistical significance of the detected correlations was defined.

River runoff in Switzerland in a changing climate – runoff regime changes and their time of emergence

Abstract. Assessments of climate change impacts on runoff regimes are essential to climate change adaptation and mitigation planning. Changing runoff regimes and thus changing seasonal patterns of water availability strongly influence various economic sectors such as agriculture, energy production, and fishery and also affect river ecology. In this study, we use new transient hydrological scenarios driven by the most up-to-date local climate projections for Switzerland, the Swiss Climate Change Scenarios. These provide detailed information on changes in runoff regimes and their time of emergence for 93 rivers in Switzerland under three Representative Concentration Pathways (RCPs): RCP2.6, RCP4.5, and RCP8.5. These transient scenarios also allow changes to be framed as a function of global mean temperature. The new projections for seasonal runoff changes largely confirm the sign of changes in runoff from previous hydrological scenarios with increasing winter runoff and decreasing summer and autumn runoff. Spring runoff is projected to increase in high-elevation catchments and to decrease in lower-lying catchments. Despite the increases in winter and some increases in spring, the annual mean runoff is projected to decrease in most catchments. Compared to lower-lying catchments, runoff changes in high-elevation catchments (above 1500 m a.s.l.) are larger in winter, spring, and summer due to the large influence of reduced snow accumulation and earlier snowmelt and glacier melt. The changes in runoff and the agreement between climate models on the sign of change both increase with increasing global mean temperatures and higher-emission scenarios. This amplification highlights the importance of climate change mitigation. The time of emergence is the time when the climate signal emerges significantly from natural variability. Under RCP8.5, times of emergence were found early, before the period 2036–2065, in winter and summer for catchments with mean altitudes above 1500 m a.s.l. Significant changes in catchments below 1500 m a.s.l. emerge later in the century. Not all catchments show significant changes in the distribution of seasonal means; thus, no time of emergence could be determined in these catchments. Furthermore, the significant changes of seasonal mean runoff are not persistent over time in some catchments due to nonlinear changes in runoff.

Spatio‐temporal assessment of the hydrological drivers of an active deep‐seated gravitational slope deformation: The Vögelsberg landslide in Tyrol (Austria)

SummarySpatio‐temporal variations of precipitation are presumed to influence the displacement rate of slow‐moving deep‐seated landslides by controlling groundwater recharge, pore‐water pressure and shear strength. Phases of landslide acceleration responding to long‐lasting rainfall and snowmelt events occur under site‐ and event‐specific time delays. Assessing groundwater recharge and simultaneous recording of landslide displacement in a sufficient spatial and temporal resolution is essential to deepen the understanding of mechanisms controlling a landslide's deformation behaviour and is indispensable when it comes to identifying and developing target‐oriented mitigation strategies. The objective of this study was to assess hydrological landslide drivers (solid and liquid precipitation, snowmelt and evapotranspiration) and to investigate their spatio‐temporal distribution in the context of movements recorded at the Vögelsberg landslide (Tyrol, Austria). Hydrometeorological variables were simulated using the AMUNDSEN (Alpine MUltiscale Numerical Distributed Simulation ENgine) hydroclimatological model and landslide movements were continuously monitored using an automated tracking total station. Area‐wide simulated time series of available water were used: (i) to separate them into single landslide triggering hydrometeorological events; (ii) to analyse spatio‐temporal patterns of water availability per triggering event including individual response times; (iii) to delineate an effective hydrological landslide catchment; and (iv) to identify relations between assessed water input and landslide displacement rate. For the observation period from 05‐2016 until 06‐2019 we identified three distinctive hydrometeorological events causing time‐delayed periods of landslide acceleration. Spatio‐temporal differences in water availability per triggering event result in spatially diverse response times varying from 20 to 60 days for rainfall‐triggered events and between 0 and 8 days for events triggered by snowmelt. Pronounced spatio‐temporal differences of snowmelt within the model domain were identified to offer a unique possibility to delineate the effective hydrological landslide catchment. While considering event‐specific time‐lags, logarithmic correlations between incoming water and landslide displacement rate become apparent.

Evidence for root adaptation to a spatially discontinuous water availability in the absence of external water potential gradients

We hereby show that root systems adapt to a spatially discontinuous pattern of water availability even when the gradients of water potential across them are vanishingly small. A paper microfluidic approach allowed us to expose the entire root system of Brassica rapa plants to a square array of water sources, separated by dry areas. Gradients in the concentration of water vapor across the root system were as small as 10-4⋅mM⋅m-1 (∼4 orders of magnitude smaller than in conventional hydrotropism assays). Despite such minuscule gradients (which greatly limit the possible influence of the well-understood gradient-driven hydrotropic response), our results show that 1) individual roots as well as the root system as a whole adapt to the pattern of water availability to maximize access to water, and that 2) this adaptation increases as water sources become more rare. These results suggest that either plant roots are more sensitive to water gradients than humanmade water sensors by 3-5 orders of magnitude, or they might have developed, like other organisms, mechanisms for water foraging that allow them to find water in the absence of an external gradient in water potential.

What about reservoirs? Questioning anthropogenic and climatic interferences on water availability

AbstractWater resources in semi‐arid regions like the Mediterranean Basin are highly vulnerable because of the high variability of weather systems. Additionally, climate change is altering the timing and pattern of water availability in a region where growing populations are placing extra demands on water supplies. Importantly, how reservoirs and dams have an influence on the amount of water resources available is poorly quantified. Therefore, we examine the impact of reservoirs on water resources together with the impact of climate change in a semi‐arid Mediterranean catchment. We simulated the Susurluk basin (23.779‐km2) using the Soil and Water Assessment Tool (SWAT) model. We generate results for with (RSV) and without reservoirs (WRSV) scenarios. We run simulations for current and future conditions using dynamically downscaled outputs of the MPI‐ESM‐MR general circulation model under two greenhouse gas relative concentration pathways (RCPs) in order to reveal the coupled effect of reservoir and climate impacts. Water resources were then converted to their usages – blue water (water in aquifers and rivers), green water storage (water in the soil) and green water flow (water losses by evaporation and transpiration). The results demonstrate that all water resources except green water flow are projected to decrease under all RCPs compared to the reference period, both long‐term and at seasonal scales. However, while water scarcity is expected in the future, reservoir storage is shown to be adequate to overcome this problem. Nevertheless, reservoirs reduce the availability of water, particularly in soil moisture stores, which increases the potential for drought by reducing streamflow. Furthermore, reservoirs cause water losses through evaporation from their open surfaces. We conclude that pressures to protect society from economic damage by building reservoirs have a strong impact on the fluxes of watersheds. This is additional to the effect of climate change on water resources.

Inter-model agreement on projected shifts in California hydroclimate characteristics critical to water management

Shifts away from the historical hydroclimate in populated regions can have dire consequences for water management. Regions like the state of California—where highly engineered, geographically interconnected, and inflexible water management systems are predicated on particular spatiotemporal patterns of water availability—are particularly vulnerable to hydroclimate shifts. However, much of the analysis of hydroclimate sensitivity to anthropogenic climate change has focused on gross metrics like annual mean precipitation, which is highly uncertain at the regional scale. This perceived uncertainty has deterred adaptation investments and quantitative integration of climate projection data into regional water management. Here, we assess projected future shifts in the state of California in a range of hydroclimate metrics critical to water management, using data from 10 statistically downscaled global climate model and two emissions scenarios currently used by the state. We find substantial inter-model agreement under both emissions scenarios—and > 80% inter-model agreement under the more severe climate change scenario—across metrics that collectively point toward an increasingly volatile, temporally concentrated, and extreme precipitation future for the state. We show, via hydrologic and operations modeling, that accounting for shifts in these more nuanced metrics reduces the projected reliability and sustainability of current water management practices to a greater degree than would be inferred from changes in total annual precipitation alone. These results highlight both the viability and critical importance of incorporating climate change projections quantitatively into water management decisions in California and other regions vulnerable to hydroclimate shifts, and underscore the need to develop integrated climate-hydrologic-operations models and decision-making protocols capable of accounting for all projected hydroclimate shifts.

Climate and phylogenetic history structure morphological and architectural trait variation among fine-root orders.

Fine roots mediate below-ground resource acquisition, yet understanding of how fine-root functional traits vary along environmental gradients, within branching orders and across phylogenetic scales remains limited. Morphological and architectural fine-root traits were measured on individual root orders of 20 oak species (genus Quercus) from divergent climates of origin that were harvested after three growing seasons in a glasshouse. These were then compared with similar measurements obtained from a phylogenetically diverse dataset of woody species from the Fine-Root Ecology Database (FRED). For the oaks, only precipitation seasonality and growing season moisture availability were correlated to aspects of root diameter and branching. Strong correlations among root diameters and architecture of different branch orders were common, while correlations between diameter and length were weakly negative. By contrast, the FRED dataset showed strong positive correlations between diameter and length and fewer correlations between root diameter and architectural traits. Our findings suggest that seasonal patterns of water availability are more important drivers of root adaptation in oaks than annual averages in precipitation and temperature. Furthermore, contrasting patterns of trait relationships between the oak and FRED datasets suggest that branching patterns are differentially constrained at narrow vs broad phylogenetic scales.