Seasonal Water Stress Research Articles

Delineation of potential zones for groundwater recharge using integrated GIS-based AHP and CSI techniques in Ogun Waterside, Southwestern Nigeria

ABSTRACT Ogun Waterside region of southwestern Nigeria experiences seasonal water stress stemming from groundwater overdraft. Therefore, it became imperative to effectively manage the existing groundwater resources to fulfill the anticipated demand for potable water. To achieve this goal, an analysis involving seven spatial parameters: geomorphology, land use/land cover, slope, lineament density, drainage density, soil types, and geology was conducted. These parameters were examined using a combination of geographic information system (GIS)-based analytical hierarchy process (AHP) and cumulative score index (CSI) techniques to delineate potential zones for groundwater recharge. The AHP methodology was employed to assign relative weights to the thematic layers and their corresponding features, reflecting their importance. The AHP results were integrated using a weighted linear combination within a GIS environment to generate the groundwater recharge potential map. Further, the CSI was used to reclassify the composite groundwater recharge potential map. The resultant map revealed three zones which were classified into high, moderate, and low potential zones founded on the CSI approximation. About 98.56 km2 (8.28%) of the study area is categorized as having low potential, 803.77 km2 (67.54%) falls within the moderate potential zone and 287.71 km2 (24.18%) falls in the high potential zone.

Beyond the “resprouter versus non‐resprouter” dichotomy: On the prevalence and evolutionary fingerprint of resprouting in tropical dry forest trees

AbstractResprouting is a plant persistence strategy in response to disturbance or stressful environmental conditions. Resprouters can dominate in stressful environments such as tropical dry forests (TDFs), but our knowledge of resprouting in TDFs is limited. Here, using a dataset of forest inventories in 16 TDF fragments (covering 15,642 trees and 321 species), we investigated patterns of resprouting in ecosystems subject to substantial seasonal water stress. We focused on two resprouting metrics: the proportion of trees that are multistemmed (resprouting frequency) and the number of stems per tree. In addition, we investigated the relative importance of environmental factors, taxonomic identity, and evolutionary history in resprouting response. Taxa with low to medium resprouting frequencies (17.19%–40.2%) are the most prevalent in TDF, compared to non‐resprouters and high‐frequency resprouters. Overall, resprouting ability appears to be an intrinsic trait that varies in response to environmental conditions but only within a range constrained by taxonomic identity. However, we found no phylogenetic signal above the genus level for any resprouting variables. Thus, the variation in resprouting across TDF lineages likely has been shaped by divergence between closely related taxa and convergence between distantly related ones, reflecting the specific environmental and disturbance factors to which they have been subjected.

Surface Energy Dynamics and Canopy Structural Properties in Intact and Disturbed Forests in the Southern Amazon

AbstractThe Brazilian Amazon has been a focus of land development with large swaths of forests converted to agriculture. Forest degradation by selective logging and fires has accompanied the agricultural frontier and has resulted in significant impacts on Amazonian ecosystems. Changes in forest structure resulting from forest disturbances have large impacts on the surface energy balance, including on land surface temperature (LST) and evapotranspiration (ET). This study's objective is to assess the effects of forest disturbances on water fluxes and forest structure in a transitional forest site in the Southern Amazon. We used ET and LST products from MODIS and Landsat 8 and GEDI‐derived forest structure data to address our research questions. We found that disturbances induced seasonal water stress, more pronounced in croplands/pastures than in forests (differences up to 20% in the dry season), and more pronounced in second‐growth and recently burned areas than in logged and intact forests (differences up to 12% in the dry season). Moreover, ET and LST were negatively related, with more consistent relationships across disturbance classes in the dry season (R2: 0.41–0.87) than in the wet season (R2: 0.18–0.49). Forest and cropland or pasture classes showed contrasting relationships in the dry season. Finally, we found that forest structure exhibited stronger relationships with ET and LST in the most disturbed forests (R2: 0.01–0.43) than in the least disturbed forests (R2 < 0.05). Our findings help to elucidate degraded forests functioning under a changing climate and to improve estimates of water and energy fluxes in Amazonian degraded forests.

Seasonal water relations and stress tolerance of quercus semecarpifolia (Smith) in treeline areas of Western Himalaya, India

Seasonal water relations and stress tolerance of quercus semecarpifolia (Smith) in treeline areas of Western Himalaya, India

Economically important species of Asteraceae: An overview of leaf epidermal micro-morphology with respect to water availability

This paper reports the result of a study undertaken with a view to documenting responses of leaf epidermal parameters of three economically important species of the family Asteraceae: Aspilia africana, Chromolaena odorata and Vernonia amygdalina from Nigeria to seasonal water stress. Obtained quantitative data showed a significant decrease (p < 0.05) in stomata density and index on the abaxial surface in Chromolaena odorata in dry conditions. The increased stomata densities and indices on the adaxial surfaces in Aspilia africana and Vernonia amygdalina in the wet season suggest that CO2 was more taken up. The reduction in stomata size (on both leaf surfaces in the three taxa) in the dry season indicated species' adaptations to dry conditions and reduction in stomatal conductance. Turgescent guard cell in the three species in the wet season indicated stomatal opening, which could, though, be a hormonal response to water availability since transpiration needed to be activated. The ability of Aspilia africana to reduce water loss and defend against herbivores greatly increased in plants that developed in dry conditions by possessing more multicellular trichomes in comparison to wet conditions, while in Vernonia amygdalina, the number increased during the wet season. Water stress had little or no effect on the micro-morphology of anticlinal walls and the shapes and arrangements of the epidermal cells in the three species. This study revealed that investigations into leaf epidermal micro-morphology might be a useful tool to elucidate the multiple mechanisms underlying leaf epidermal structure function in response to water availability.

Rainfall trends and district-wise drought climatology during southwest monsoon season over Bundelkhand region of Uttar Pradesh, India

Drought is a climatic anomaly that can occur in all regions with vastly different climate. A persistent lack of precipitation over an extended period scaling usually a season or more results water stress that significantly impacts economic, agricultural, environmental and social aspects. For an effective monitoring of drought condition, drought indices play major role which are region specific and have limitation of applicability in different climatic condition. Hence, the present study aims to analyse the climatology and drought by two drought indices viz. Standard Precipitation Index (SPI) and standardized precipitation evapotranspiration index (SPEI)) for Bundelkhand region, the most drought prone area of Central India by using 48 years (1969-2016) rainfall and temperature data. The trend analysis was performed at a significance level of 5% by using non parametric Mann-Kendall (MK) test and Sen’s slope estimator with the help of XLSTAT 2021 software. The SPI and SPEI were calculated with the SPEI R package in R-Studio software. The study revealed that i) the southwest monsoon (June to September) contributed 88.8-91.8% of total annual rainfall with coefficient of variation (CV) of 29.9-39.5%. ii) A non- significant decreasing trend in rainfall was noticed for almost all the districts during July, August and September. However, a significant (0.05 level) and decreasing trend was observed in July (4.03 mm rainfall/year) and August rainfall (4.03 mm rainfall/year) for Hamirpur. iii) The frequency of moderate drought events increased followed by severe and extreme drought events. The decreasing trends of SPI-3 and SPEI-3 were also observed which indicates more dry spells during southwest monsoon season. iv) A good correlation (r= value of 0.88 to 0.91) was observed between SPI-3 and SPEI-3 during southwest monsoon season which indicates the importance of theses indices for assessment of drought in the study region.

Possible negative effects of earlier thaw onset and longer thaw duration on vegetation greenness over the Tibetan Plateau

The Tibetan Plateau (TP), also known as the world's Third Pole, is underlain by frozen ground and is highly sensitive to climate change. However, it remains unclear how the variations in soil freeze-thaw could affect vegetation dynamics across the TP. In this study, we adopted the latest datasets for vegetation, climate and soil freeze-thaw in the past two decades to explore the possible impacts of changes in soil freeze-thaw on vegetation greenness and phenology on the TP. According to the satellite-based observations, the TP showed an overall greening trend during 2001-2020, and the growing season length increased significantly at a rate of 3.6 days/10a, mainly contributed by the advances of the start of the growing season (2.7 days/10a). Based on ridge regression and partial correlation analysis, air temperature and precipitation were found to be the major dominant factors of vegetation dynamics on the TP, and precipitation played a dominant role in the relatively warm-dry southwestern TP where vegetation browning and spring phenology delays were observed. In the relatively cold regions, earlier soil thaw onset generally facilitated spring phenology, and longer soil thaw duration tended to increase the growing season soil moisture content, which could in turn enhance vegetation greenness. In the relatively warm regions, however, earlier thaw onset and longer thaw duration could possibly exacerbate the growing season water stress and limit vegetation growth. The negative impacts were more evident in the regions with unstable and completely degraded permafrost according to the results in the source region of Yellow and Yangtze rivers. Our findings highlight the spatially varying role of soil freeze-thaw changes in vegetation dynamics, which have important implications for the carbon budget of the TP in a warming future climate as frozen ground continues to degrade.

Productivity and Feed Quality Performance of Napier Grass (Cenchrus purpureus) Genotypes Growing under Different Soil Moisture Levels.

In the semi-arid and arid environments of Sub-Sharan Africa, forage availability throughout the year is insufficient and highly limited during the dry seasons due to limited precipitation. Thus, the identification of drought stress-tolerant forage cultivars is one of the main activities in forage development programs. In this study, Napier grass (Cenchrus purpureus), an important forage crop in Eastern and Central Africa that is broadly adapted to produce across tropical environments, was evaluated for its water use efficiency and production performance under field drought stress conditions. Eighty-four Napier grass genotypes were evaluated for their drought stress tolerance from 2018 to 2020 using agro-morphological and feed quality traits under two soil moisture stress regimes during the dry season, i.e., moderate (MWS) and severe (SWS) water stress conditions, and under rainfed conditions in the wet season (wet). Overall, the results indicated the existence of genotype variation for the traits studied. In general, the growth and productivity of the genotypes declined under SWS compared to MWS conditions. High biomass-yielding genotypes with enhanced WUE were consistently observed across harvests in each soil moisture stress regime. In addition, the top biomass-yielding genotypes produced the highest annual crude protein yield, indicating the possibility of developing high-feed-quality Napier grass genotypes for drought stress environments.

Meta-analysis of the correlation between vegetation and precipitation in the temperate deserts of the Northern Hemisphere over the last 40 years

Temperate desert vegetation (TDV) is subjected to long-term seasonal or intermittent water stress, and precipitation is the main water source for desert vegetation. However, due to the limitations of existing research methods, data resources and spatiotemporal differences, universal conclusions and benchmark references at large spatial scales under the background of climate warming have been lacking in recent decades. In a systematic review, we evaluated primary studies and comprehensively analyzed the pooled correlation (pooled r (Pr)) between precipitation and TDV (P-TDV) in the Northern Hemisphere (NH) over the past 40 years by using a meta-analysis method to explore the monthly scale response pattern and heterogeneity pattern and to reveal the key TDV growth period under drought stress at a large spatial scale. The results showed the following. (1) In the mean state, the correlation between precipitation and TDV was at a moderate level in the NH over the last 40 years (Pr = 0.31). The spring Pr value was lowest, and the results were nonsignificant (p > 0.05). The highest Pr value was 0.40, and this value appeared in summer, followed by a value of 0.22 in autumn; the strongest relationship was found in June (Pr = 0.56). (2) The Pr values of TDV and precipitation with 1- and 2-month lag times were 0.34 and 0.31, respectively; these values were higher than those derived using lag times longer than 2 months. The statistical results were all significant and reflected a moderate correlation level. The above conclusions showed that TDV growth has the strongest demand for water in June and that spring drought conditions may have been one of the main stress factors affecting the growth of desert vegetation at the intra-annual scale in the northern temperate zone over the past 40 years.

Water use strategies between two co‐occurring woody species in a riparian area: Naturally occurring willow,Salix exigua, and expanding juniper,Juniperus scopulorum, in central Montana

AbstractJuniper expansion across the western United States has the potential to alter watershed hydrology, especially within riparian areas. Given the uncertainties in the ecohydrological response to the expansion, this study focused on examining the water use strategies between two woody species co‐occurring in a riparian area in south central Montana—Salix exigua(sandbar willows) andJuniperus scopulorum(rocky mountain junipers)—in order to address three questions: (1) Are junipers and willows using the same soil moisture pool that contributes to streamflow? (2) Are junipers transpiring more water than willows on a per tree or per sapwood area basis? (3) Are the seasonal transpiration rates between junipers and willows different? To determine the differences in water use strategies between willows and junipers, we used stable isotope analyses to trace different sources of water, water potential to determine seasonal water stress patterns and transpiration rates to quantify water loss. Our isotopic analyses suggest that junipers and willows in the riparian area were not directly using stream water but relied on different pools of soil water at different times of the year: shallow soil water in spring when soils were wet and deeper soil water in late summer. We also found that junipers transpired more than willows during the spring and late fall, but that both species had similar transpiration rates during periods of low streamflow. However, higher juniper transpiration rates in spring and late fall can potentially lead to soil moisture deficits if winter snowpack is low, suggesting that the additional water loss through transpiration by junipers may be mitigated under wet winters but exacerbated under dry winters.

Chickpeas from a Chilean Region Affected by a Climate-Related Catastrophe: Effects of Water Stress on Grain Yield and Flavonoid Composition.

The Valparaiso region in Chile was decreed a zone affected by catastrophe in 2019 as a consequence of one of the driest seasons of the last 50 years. In this study, three varieties (‘Alfa-INIA’, ‘California-INIA’, and one landrace, ‘Local Navidad’) of kabuli-type chickpea seeds produced in 2018 (control) and 2019 (climate-related catastrophe, hereafter named water stress) were evaluated for their grain yield. Furthermore, the flavonoid profile of both free and esterified phenolic extracts was determined using liquid chromatography-mass spectrometry, and the concentration of the main flavonoid, biochanin A, was determined using liquid chromatography with diode array detection. The grain yield was decreased by up to 25 times in 2019. The concentration of biochanin A was up to 3.2 times higher in samples from the second season (water stress). This study demonstrates that water stress induces biosynthesis of biochanin A. However, positive changes in the biochanin A concentration are overshadowed by negative changes in the grain yield. Therefore, water stress, which may be worsened by climate change in the upcoming years, may jeopardize both the production of chickpeas and the supply of biochanin A, a bioactive compound that can be used to produce dietary supplements and/or nutraceuticals.

Topographical influences on foliar nitrogen concentration and stable isotope composition in a Mediterranean-climate catchment

Nitrogen (N) oligotrophication is increasing globally across terrestrial ecosystems and manifested in decreasing nitrogen concentration ([N]) and changes in the stable nitrogen isotope composition (δ15N) of foliage. Heterogeneity in plant nitrogen sources makes it challenging to detect the effects of N oligotrophication even at a small catchment scale with complex topography. Understanding the spatial and temporal variation of foliar δ15N and [N] at such a scale is required to develop useful ecological indicators and monitoring methods to support catchment management with a potential N oligotrophication problem. This study examined spatial and high-resolution temporal variation of foliar δ15N and [N] and their influencing factors in ten trees grouped by Eucalyptus and Acacia in a native forest vegetation catchment. Over 16 sampling campaigns within a 12-month period, foliar δ15N and [N] increased in Eucalyptus but were constant in the N2-fixing Acacia. The higher foliar [N] and δ15N in Acacia reflected its N2-fixation ability. Topographic flow accumulation area (NDVI) explained 46% (77%) of spatial variation in dry-season Eucalyptus foliar δ15N ([N]). For Eucalyptus, foliar δ15N was higher at the downslope than the upslope locations, but no hillslope location differences were observed for foliar [N]. These results suggest that in the non-N2-fixing Eucalyptus, seasonal water stress related nitrogen availability may be reflected in foliar δ15N rather than foliar [N]. As such, foliar δ15N of non-N2-fixing plants potentially is a more sensitive indicator of seasonal or topographical N availability than foliar [N].

Assessing the grapevine crop water stress indicator over the flowering-veraison phase and the potential yield lose rate in important European wine regions

In Europe, most of vineyards are managed under rainfed conditions, where water deficit has become increasingly an issue. The flowering-veraison phenophase represents an important period for vine response to water stress, which is known to depend on variety characteristics, soil and climate conditions. In this paper, we have carried out a retrospective analysis for important European wine regions over 1986–2015, with objectives to assess the mean Crop Water Stress Indicator (CWSI) during flowering-veraison phase, and potential Yield Lose Rate (YLR) due to seasonal cumulative water stress. Moreover, we also investigate if advanced flowering-veraison phase can lead to alleviated CWSI under recent-past conditions, thus contributing to reduced YLR. A process-based grapevine model is employed, which has been extensively calibrated for simulating both flowering and veraison stages using location-specific observations representing 10 different varieties. Subsequently, grid-based modelling is implemented with gridded climate and soil datasets and calibrated phenology parameters. The findings suggest wine regions with higher mean CWSI of flowering-veraison phase tend to have higher potential YLR. However, contrasting patterns are found between wine regions in France-Germany-Luxembourg and Italy-Portugal-Spain. The former tends to have slight-to-moderate drought conditions (CWSI<0.5) along with a negligible-to-moderate YLR (<30%), whereas the latter is found to have severe-to-extreme drought (CWSI>0.5) and substantial YLR (>40%). Wine regions prone to a high drought risk (CWSI>0.75) are also identified, which are concentrated in southern Mediterranean Europe. Advanced flowering-veraison phase over 1986–2015, could have benefited from more spring precipitation and cooler temperatures for wine regions of Italy-Portugal-Spain, leading to reduced mean CWSI and YLR. For those of France-Germany-Luxembourg, this can have reduced flowering-veraison precipitation, but prevalent reductions of YLR are also found, possibly due to shifted phase towards a cooler growing-season with reduced evaporative demands. Our study demonstrates flowering-verasion water deficit is critical for potential yield, which can have different impacts between Central and Southern European wine regions. This phase can be advanced under a warmer climate, thus having important implications for European rainfed vineyards. The overall outcome may provide new insights for appropriate viticultural management of seasonal water deficits under climate change.

Estimation of Daily Water Table Level with Bimonthly Measurements in Restored Ombrotrophic Peatland

Daily measurements of the water table depth are sometimes needed to evaluate the influence of seasonal water stress on Sphagnum recolonization in restored ombrotrophic peatlands. However, continuous water table measurements are often scarce due to high costs and, as a result, water table depth is more commonly measured manually bimonthly with daily logs in few reference wells. A literature review identified six potential methods to estimate daily water table depth with bimonthly records and daily measurements from a reference well. A new estimation method based on the time series decomposition (TSD) is also presented. TSD and the six identified methods were compared with the water table records of an experimental peatland site with controlled water table regime located in Eastern Canada. The TSD method was the best performing method (R2 = 0.95, RMSE = 2.48 cm and the lowest AIC), followed by the general linear method (R2 = 0.92, RMSE = 3.10 cm) and support vector machines method (R2 = 0.91, RMSE = 3.24 cm). To estimate daily values, the TSD method, like the six traditional methods, requires daily data from a reference well. However, the TSD method does not require training nor parameter estimation. For the TSD method, changing the measurement frequency to weekly measurements decreases the RMSE by 16% (2.08 cm); monthly measurements increase the RMSE by 13% (2.80 cm).

Non-structural carbohydrates mediate seasonal water stress across Amazon forests

Non-structural carbohydrates (NSC) are major substrates for plant metabolism and have been implicated in mediating drought-induced tree mortality. Despite their significance, NSC dynamics in tropical forests remain little studied. We present leaf and branch NSC data for 82 Amazon canopy tree species in six sites spanning a broad precipitation gradient. During the wet season, total NSC (NSCT) concentrations in both organs were remarkably similar across communities. However, NSCT and its soluble sugar (SS) and starch components varied much more across sites during the dry season. Notably, the proportion of leaf NSCT in the form of SS (SS:NSCT) increased greatly in the dry season in almost all species in the driest sites, implying an important role of SS in mediating water stress in these sites. This adjustment of leaf NSC balance was not observed in tree species less-adapted to water deficit, even under exceptionally dry conditions. Thus, leaf carbon metabolism may help to explain floristic sorting across water availability gradients in Amazonia and enable better prediction of forest responses to future climate change.

Spatially variable hydrologic impact and biomass production tradeoffs associated with Eucalyptus (E. grandis) cultivation for biofuel production in Entre Rios, Argentina

AbstractClimate change and energy security promote using renewable sources of energy such as biofuels. High woody biomass production achieved from short‐rotation intensive plantations is a strategy that is increasing in many parts of the world. However, broad expansion of bioenergy feedstock production may have significant environmental consequences. This study investigates the watershed‐scale hydrological impacts of Eucalyptus (E. grandis) plantations for energy production in a humid subtropical watershed in Entre Rios province, Argentina. A Soil and Water Assessment Tool (SWAT) model was calibrated and validated for streamflow, leaf area index (LAI), and biomass production cycles. The model was used to simulate various Eucalyptus plantation scenarios that followed physically based rules for land use conversion (in various extents and locations in the watershed) to study hydrological effects, biomass production, and the green water footprint of energy production. SWAT simulations indicated that the most limiting factor for plant growth was shallow soils causing seasonal water stress. This resulted in a wide range of biomass productivity throughout the watershed. An optimization algorithm was developed to find the best location for Eucalyptus development regarding highest productivity with least water impact. E. grandis plantations had higher evapotranspiration rates compared to existing terrestrial land cover classes; therefore, intensive land use conversion to E. grandis caused a decline in streamflow, with January through March being the most affected months. October was the least‐affected month hydrologically, since high rainfall rates overcame the canopy interception and higher ET rates of E. grandis in this month. Results indicate that, on average, producing 1 kg of biomass in this region uses 0.8 m3 of water, and the green water footprint of producing 1 m3 fuel is approximately 2150 m3 water, or 57 m3 water per GJ of energy, which is lower than reported values for wood‐based ethanol, sugar cane ethanol, and soybean biodiesel.

Implications of the Symbiotic Nitrogen Fixation in Common Bean under Seasonal Water Stress

The objective of this research was to study the performance of 10 common bean genotypes under water deficit stress and how it affects to their symbiotic relationship with 10 Rhizobium strains in both greenhouse and field conditions. PHA-0471, a small seeded genotype had the best yield under irrigation and under water stress. Other genotypes with tolerance to drought were the large-seeded PHA-0432 and PHA-0683. In the Rhizobium inoculation tests it was observed that the increase of dry nodular weight produced less seed yield in beans. PHA-0683 genotype presented a great uniformity on nodule size and an association with yield when it displays the big nodule phenotype. Further research about this would be interesting because this fact could be due to the existence of a plant blocking mechanism for inefficient strain nodules. The inoculated plants were productive in irrigated fields and in drought ones and their productivity was the same or even better than the N supplemented plant control. The genotype-strain relationship was very specific and the local strains achieved the greatest productivity with some genotypes in irrigated and drought conditions that make possible their use as inoculating strains, with relevance for the environmental impact of agriculture.

Simulating the Production of Rice Genotypes by Flood Management and End-Season Water Stress Conditions Using AquaCrop Model

ABSTRACT The present study was conducted to assess the ability of AquaCrop model in predicting of grain and biological yield of rice genotypes in water management. A two-year field experiment was conducted at the experimental farm of the Iranian Rice Research Institute in Rasht, Iran from 2016 to 2017. The experiment was established in a split-plot design with two irrigation management (continuous submergence and end season water stress) as the main plot, fourth rice genotypes as the sub-plot and three replications. The goodness-of-fit between observed and simulated grain yield and final biomass was assessed by means of the coefficient of determination (R 2), the absolute and normalized root mean square errors (RMSE). The RMSEn of predicting grain yield at calibration and evaluation stages was in the range of 6–12% and 6–8% for biological yield. The results indicated that AquaCrop model is suitable to predict grain yield and biological yield of rice genotypes in northern Iran. AquaCrop model can be used to determine optimization strategies to improve the water consumption of rice genotypes.

Regional and seasonal water stress analysis of United States thermoelectricity

Most thermoelectric power plants in the United States (U.S.) rely on fresh water for cooling, resulting in significant water consumption. An understanding of the regional and seasonal water stress impact of such water consumption is needed. In this study, we used a U.S. county-level water stress index, Available Water Remaining for the United States (AWARE-US), with facility-level thermoelectric power generation water consumption data, to quantify the regional and seasonal water stress impact of U.S. thermoelectric power plants. Water stress impact was evaluated as water-scarcity footprint (WSF) using monthly AWARE-US data. Results show that most thermoelectric power plants in the United States that use fresh water are in water-abundant regions. Our findings also show that a small fraction of the U.S. thermoelectric generation facilities (13% by power) located in water stressed regions contribute the most water stress impact (88% of the total WSF) caused by thermoelectric power generation in the U.S. Even if fresh water is abundant on an annual basis, many power plants are in counties with seasonal water shortages. Of the 401 counties with thermoelectric power plants using fresh water for cooling, 80 counties in February and 160 counties in August had fresh water withdrawal requirements that exceeded the sustainable fresh water available (availability minus demand or AMD) in that region. This means that 27% and 46% of power generation facilities have difficulty securing sustainable fresh water in February and August, respectively. This study is intended to support water consumption management in existing power plants and guide the deployment of future power plants to mitigate water stress impact.

Balancing Water Sustainability and Productivity Objectives in Microalgae Cultivation: Siting Open Ponds by Considering Seasonal Water-Stress Impact Using AWARE-US.

Microalgae have great potential as an energy and feed resource. Here we evaluate the water use associated with freshwater algae cultivation and find it is possible to scale U.S. algae biofuel production to 20.8 billion liters of renewable diesel annually without significant water-stress impact. Among potential sites, water-stress is significantly more variable than algae productivity across location and season. Thus, it is possible to reduce water-stress impact, quantified as water scarcity footprint, through the choice of algae site location. We test three site-selection criteria based on (1) biomass productivity, (2) water-use efficiency, and (3) water-stress impact and find that adding water-stress constraints to productivity-based ranking of suitable sites reduces water-stress impact by 97% and water consumption by half, compared with biomass-productivity ranking alone, with little productivity impact (<1.7% per-site on average). With 20.8 billion liters, algae could meet 19.7% of U.S. jet fuel demand with a freshwater demand of less than 1.4% of U.S. irrigation consumption. Evaluating water-stress impact is important because the impact of unit water consumption on water stress varies significantly across regions and seasons. Considering seasonal water balances allows producers to understand the combined seasonal effects of hydrologic flows and productivity, thereby avoiding potential short-term water stress.