Water and climate: Recognize anthropogenic drought

AghaKouchak, Amir; Feldman, David L.; Hoerling, Martin P.; Huxman, Travis E.; Lund, Jay R.

doi:10.1038/524409a

Cited by 303 publications

(173 citation statements)

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“…After oxidation by potassium permanganate, sodium nitrite and concentrated sulfuric acid, followed by exfoliation in water, monolayer GO-NS with a typical lateral size of several microns to several hundred nanometers and a thickness of~1 nm are generally obtained (Figure 1c). Figures 1d and e show the SEM and atomic force microscopy images of the Mg-Al-CO 3 2 − LDH precursors and the exfoliated NS (characterizations for the corresponding Co-Al forms are shown in Supplementary Figure S1). The LDH platelets are well crystallized, with a regular hexagonal shape and lateral dimensions on the order of several microns (Figure 1d and Supplementary Figure S1a).…”

Section: Results and Discussion Preparation Of Go-ns Ldh-ns And Go/lmentioning

confidence: 99%

“…The thicknesses of both GO and LDH-NS as measured by atomic force microscopy are slightly greater than their crystallographic thicknesses, a possible effect of surface adsorption. It should be noted that the thorough decarbonation and exchange into the NO 3 − form is the prerequisite for efficient exfoliation of LDH platelets into monolayer NS because of the high affinity and strong coupling of CO 3 2 − ions in between LDH host layers, which impede the delamination of the LDH platelets. As shown in the X-ray diffraction (XRD) patterns in Supplementary Figures S2a and c, after mechanical shaking in NaNO 3 /HNO 3 mixtures, both the Mg-Al-CO 3 2 − and Co-Al-CO 3 2 − LDH platelets are completely exchanged into their NO 3 − forms with an increased interlayer spacing of~0.87 nm, compared with~0.73 nm in the CO 3 2 − forms.…”

Section: Results and Discussion Preparation Of Go-ns Ldh-ns And Go/lmentioning

confidence: 99%

“…The preparation of Co-Al and Mg-Al LDH-NS, which followed previously developed soft-chemical procedures, 40,41 involved the synthesis of Co-Al-CO 3 2 − and Mg-Al-CO 3 2 − LDH hexagon platelets by refluxing and hydrothermal treatment, respectively, decarbonation and anion exchange into NO 3 − forms by a salt-acid treatment with NaNO 3 and HNO 3 mixed solutions under mechanical shaking, and delamination/exfoliation of Co-Al-NO 3 − and Mg-Al-NO 3 − LDH platelets in formamide under mechanical shaking.…”

Section: Co-al and Mg-al Ldh-ns Preparationmentioning

confidence: 99%

“…[1][2][3] For this purpose, the development of membranes with novel separation functions is a key objective.…”

Section: Introductionmentioning

confidence: 99%

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Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Sun

et al. 2016

NPG Asia Mater

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The development of graphene-based functional membranes with the ability to effectively filter and separate molecules or ions in solutions based on a simple criterion (for example, the size or charge of solutes) is crucial for various engineering-relevant applications, ranging from wastewater purification and reuse to chemical refinement. Here, we report a hybrid membrane consisting of anionic graphene oxide (GO) and cationic Co-Al (or Mg-Al) layered double hydroxide (LDH) nanosheet (NS) superlattice units for high selectivity charge-guided ion transport. The hybrid membrane possesses a series of characteristics, including being easy to access, mechanically robust, freestanding, flexible and semitransparent as well as having a large area. The interlayer spacing of the hybrid membrane is insensitive to humidity variations, ensuring the structural stability in solution-based mass transport applications. The concentration gradient-driven ion transmembrane diffusion experiments show that the cations bearing various valences can be effectively separated strictly according to their charges, independent of the cationic and charge-balancing anionic species. The relative selectivity of the hybrid membranes toward monovalent and trivalent cations is as high as 30, which is not achievable by GO multilayer stacks, LDH-NS multilayer stacks or their bulk-stratified membranes, indicating that a synergistic effect originating from the molecular-level heteroassembly of GO and LDH-NS has a dominant role in the high-performance charge-guided ion filtration and separation processes. These excellent properties of GO/LDH-NS hybrid membranes make them promising candidates in diverse applications, ranging from wastewater treatment and reuse and chemical refinement to biomimetic selective ion transport.

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Section: Results and Discussion Preparation Of Go-ns Ldh-ns And Go/lmentioning

confidence: 99%

Section: Results and Discussion Preparation Of Go-ns Ldh-ns And Go/lmentioning

confidence: 99%

Section: Co-al and Mg-al Ldh-ns Preparationmentioning

confidence: 99%

“…[1][2][3] For this purpose, the development of membranes with novel separation functions is a key objective.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Sun

et al. 2016

NPG Asia Mater

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“…Operational drought is defined as a period with anomalous supply failures in a developed water system (Pedro-Monzonìs et al, 2015). It is caused by a combination of two factors: lack of water resources and excess of demand (Mishra and Singh, 2010;AghaKouchak, 2015a). Moreover, it can be further worsened by an inadequate design and management of the water exploitation system and its operating rules (Mishra and Singh, 2010).…”

Section: Introductionmentioning

confidence: 99%

Automatic design of basin-specific drought indexes for highly regulated water systems

Zaniolo

Giuliani

Castelletti

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. Socio-economic costs of drought are progressively increasing worldwide due to undergoing alterations of hydro-meteorological regimes induced by climate change. Although drought management is largely studied in the literature, traditional drought indexes often fail at detecting critical events in highly regulated systems, where natural water availability is conditioned by the operation of water infrastructures such as dams, diversions, and pumping wells. Here, ad hoc index formulations are usually adopted based on empirical combinations of several, supposed-to-be significant, hydro-meteorological variables. These customized formulations, however, while effective in the design basin, can hardly be generalized and transferred to different contexts. In this study, we contribute FRIDA (FRamework for Index-based Drought Analysis), a novel framework for the automatic design of basin-customized drought indexes. In contrast to ad hoc empirical approaches, FRIDA is fully automated, generalizable, and portable across different basins. FRIDA builds an index representing a surrogate of the drought conditions of the basin, computed by combining all the relevant available information about the water circulating in the system identified by means of a feature extraction algorithm. We used the Wrapper for Quasi-Equally Informative Subset Selection (W-QEISS), which features a multi-objective evolutionary algorithm to find Pareto-efficient subsets of variables by maximizing the wrapper accuracy, minimizing the number of selected variables, and optimizing relevance and redundancy of the subset. The preferred variable subset is selected among the efficient solutions and used to formulate the final index according to alternative model structures. We apply FRIDA to the case study of the Jucar river basin (Spain), a drought-prone and highly regulated Mediterranean water resource system, where an advanced drought management plan relying on the formulation of an ad hoc "state index" is used for triggering drought management measures. The state index was constructed empirically with a trial-and-error process begun in the 1980s and finalized in 2007, guided by the experts from the Confederación Hidrográfica del Júcar (CHJ). Our results show that the automated variable selection outcomes align with CHJ's 25-year-long empirical refinement. In addition, the resultant FRIDA index outperforms the official State Index in terms of accuracy in reproducing the target variable and cardinality of the selected inputs set.

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Does El Niño intensity matter for California precipitation?

Hoell

Hoerling

Eischeid

et al. 2016

Geophysical Research Letters

Self Cite

102

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The sensitivity of California precipitation to El Niño intensity is investigated by applying a multimodel ensemble of historical climate simulations to estimate how November–April precipitation probability distributions vary across three categorizations of El Niño intensity. Weak and moderate El Niño events fail to appreciably alter wet or dry risks across northern and central California, though odds for wet conditions increase across southern California during moderate El Niño. Significant increases in wet probabilities occur during strong El Niño events across the entire state. In California's main northern watershed regions, simulations indicate an 85% chance of greater than normal precipitation and a 50% probability of at least 125% of normal. Our results indicate that both the statewide average and the spatial distribution of California precipitation are sensitive to El Niño intensity. Forecasts of El Niño intensity would thus contribute to improved situational awareness for California water planning and related water resource impacts.

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Water and climate: Recognize anthropogenic drought

Cited by 303 publications

References 9 publications

Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Automatic design of basin-specific drought indexes for highly regulated water systems

Does El Niño intensity matter for California precipitation?

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