Early Drought Research Articles

QTL controlling grain filling under terminal drought stress in a set of wild barley introgression lines.

Drought is a major abiotic stress impeding the yield of cereal crops globally. Particularly in Mediterranean environments, water becomes a limiting factor during the reproductive developmental stage, causing yield losses. The wild progenitor of cultivated barley Hordeum vulgare ssp spontaneum (Hsp) is a potentially useful source of drought tolerance alleles. Wild barley introgression lines like the S42IL library may facilitate the introduction of favorable exotic alleles into breeding material. The complete set of 83 S42ILs was genotyped with the barley 9k iSelect platform in order to complete genetic information obtained in previous studies. The new map comprises 2,487 SNPs, spanning 989.8 cM and covering 94.5% of the Hsp genome. Extent and positions of introgressions were confirmed and new information for ten additional S42ILs was collected. A subset of 49 S42ILs was evaluated for drought response in four greenhouse experiments. Plants were grown under well-watered conditions until ten days post anthesis. Subsequently drought treatment was applied by reducing the available water. Several morphological and harvest parameters were evaluated. Under drought treatment, trait performance was reduced. However, there was no interaction effect between genotype and treatment, indicating that genotypes, which performed best under control treatment, also performed best under drought treatment. In total, 40 QTL for seven traits were detected in this study. For instance, favorable Hsp effects were found for thousand grain weight (TGW) and number of grains per ear under drought stress. In particular, line S42IL-121 is a promising candidate for breeding improved malting cultivars, displaying a TGW, which was increased by 17% under terminal drought stress due to the presence of an unknown wild barley QTL allele on chromosome 4H. The introgression line showed a similar advantage in previous field experiments and in greenhouse experiments under early drought stress. We, thus, recommend using S42IL-121 in barley breeding programs to enhance terminal drought tolerance.

Improved short-term drought response of transgenic rice over-expressing maize C4 phosphoenolpyruvate carboxylase via calcium signal cascade

To understand the link between long-term drought tolerance and short-term drought responses in plants, transgenic rice (Oryza sativa L.) plants over-expressing the maize C4-pepc gene encoding phosphoenolpyruvate carboxylase (PC) and wild-type (WT) rice plants were subjected to PEG 6000 treatments to simulate drought stress. Compared with WT, PC had the higher survival rate and net photosynthetic rate after 16days of drought treatment, and had higher relative water content in leaves after 2h of drought treatment as well, conferring drought tolerance. WT accumulated higher amounts of malondialdehyde, superoxide radicals, and H2O2 than PC under the 2-h PEG 6000 treatment, indicating greater damages in WT. Results from pretreatments with a Ca2+ chelator and/or antagonist showed that the regulation of the early drought response in PC was Ca2+-dependent. The NO and H2O2 levels in PC lines were also up-regulated via Ca2+ signals, indicating that Ca2+ in PC lines also reacted upstream of NO and H2O2. 2-h drought treatment increased the transcripts of CPK9 and CPK4 in PC via positive up-regulation of Ca2+. The transcripts of NAC6 [NACs (NAM, ATAF1, ATAF2, and CUC2)] and bZIP60 (basic leucine zipper, bZIP) were up-regulated, but those of DREB2B (dehydration-responsive element-binding protein, DREB) were down-regulated, both via Ca2+ signals in PC. PEPC activity, expressions of C4-pepc, and the antioxidant enzyme activities in PC lines were up-regulated via Ca2+. These results indicated that Ca2+ signals in PC lines can up-regulate the NAC6 and bZIP60 and the downstream targets for early drought responses, conferring drought tolerance for the long term.

Early detection of water stress in maize based on digital images

Early water stress detection is of great significance in precision plant breeding and agricultural production. In the field, outdoor cameras would be an applicable tool for early drought stress detection with high-resolution images. Based on image analysis, we presented a model to detect water stress of maize in the early stage. In the red-green-blue (RGB) color space, a simple linear classifier was proposed to extract green vegetation from maize images. After color image segmentation, fourteen-dimensional color and texture features were extracted from each image. Three water treatment levels (well-watered, reduced watered and drought stressed) were applied to maize plants. We adopted a two-stage detection model trained with different feature subsets to evaluate the water stress. The water stress detection model was based on a supervised learning algorithm, gradient boosting decision tree (GBDT). The recognition accuracy of three water treatments (ATWT) was 80.95% and the accuracy of water stress (AWS) reached 90.39%. Results showed that the proposed method had an effective detection performance between water suitability and water stress conditions in the maize fields.

Large precipitation event variability among headwater SNOTEL sites and impacts on streamflow in the Upper Colorado River Basin

ABSTRACTThis exploratory study defines and characterizes large precipitation events (LPEs) at a sample of snow telemetry (SNOTEL) sites located in headwater subbasins of the Upper Colorado River Basin (UCRB) and assesses the relationships of interannual LPE variability on basin streamflow. LPE thresholds are defined as the 80th percentile of daily precipitation increments observed at each SNOTEL site from 1981 to 2014. On average, LPEs accounted for more than half (55.5%) of annual precipitation. Total precipitation, total LPE precipitation, LPE count, and LPE magnitude are assessed annually at each SNOTEL site. Statistical analysis shows that these LPE metrics, observed at the headwater SNOTEL sites, are strongly correlated with total annual streamflow downstream, as measured at river gages on major tributaries in the UCRB and at Lake Powell. Further analysis of streamflow during the early twenty-first century drought suggests that drought conditions have coincided with lower precipitation observed at the SNOTEL sites, due in part to fewer and drier LPEs in recent years. Investigation of upper air patterns during LPEs reveals that such events most commonly coincide with zonal, onshore flow among the northern subbasins and amplified troughs towards the south of the UCRB, patterns which have been less common during the drought.

Contrasting dynamics of leaf potential and gas exchange during progressive drought cycles and recovery in Amorpha fruticosa and Robinia pseudoacacia

Leaf gas exchange is closely associated with water relations; however, less attention has been given to this relationship over successive drought events. Dynamic changes in gas exchange and water potential in the seedlings of two woody species, Amorpha fruticosa and Robinia pseudoacacia, were monitored during recurrent drought. The pre-dawn leaf water potential declined in parallel with gas exchange in both species, and sharp declines in gas exchange occurred with decreasing water potential. A significant correlation between pre-dawn water potential and gas exchange was observed in both species and showed a right shift in R. pseudoacacia in the second drought. The results suggested that stomatal closure in early drought was mediated mainly by elevated foliar abscisic acid (ABA) in R. pseudoacacia, while a shift from ABA-regulated to leaf-water-potential-driven stomatal closure was observed in A. fruticosa. After re-watering, the pre-dawn water potential recovered quickly, whereas stomatal conductance did not fully recover from drought in R. pseudoacacia, which affected the ability to tightly control transpiration post-drought. The dynamics of recovery from drought suggest that stomatal behavior post-drought may be restricted mainly by hydraulic factors, but non-hydraulic factors may also be involved in R. pseudoacacia.

Toward a categorical drought prediction system based on U.S. Drought Monitor (USDM) and climate forecast

Disastrous impacts of recent drought events around the world have led to extensive efforts in drought monitoring and prediction. Various drought information systems have been developed with different indicators to provide early drought warning. The climate forecast from North American Multimodel Ensemble (NMME) has been among the most salient progress in climate prediction and its application for drought prediction has been considerably growing. Since its development in 1999, the U.S. Drought Monitor (USDM) has played a critical role in drought monitoring with different drought categories to characterize drought severity, which has been employed to aid decision making by a wealth of users such as natural resource managers and authorities. Due to wide applications of USDM, the development of drought prediction with USDM drought categories would greatly aid decision making. This study presented a categorical drought prediction system for predicting USDM drought categories in the U.S., based on the initial conditions from USDM and seasonal climate forecasts from NMME. Results of USDM drought categories predictions in the U.S. demonstrate the potential of the prediction system, which is expected to contribute to operational early drought warning in the U.S.

Impact of irrigation on plant growth and development of white cabbage

It is widely known that an optimal irrigation water supply is a key to high horticultural productivity, efficient water use, and the reduction of off-site effects due to percolation of excess water. To promote better agronomic practices in irrigated horticulture, three different irrigation scheduling approaches based on soil water balance calculations, soil water potential measurements (sensor-based), and crop growth model simulations, were evaluated in a two-year field experiment. The experiments were conducted with white cabbage on a loamy sand soil near Dresden, Germany. The results show that sensor-based irrigation, at a soil water potential of −250hPa measured at a soil depth of 30cm, achieved high yields with moderate to low irrigation water inputs. Irrigation scheduling based on soil water balance calculations led to unproductive over-irrigation due to overestimated crop coefficients, which highlight the need for more accurate estimates of these coefficients. Simulation-based irrigation scheduling resulted in acceptable water productivities but can only be recommended to farmers to some extent because it requires a robust crop model calibration. Analysis of the plant development indicates that maintenance of field capacity until the end of head formation is favorable. Drought stress lead to reduced plant heights, leaf area indices and head yields. Furthermore, the results show that early drought stress effects can be compensated by an appropriate water supply in later growing stages.

Effects of Altered Seasonality of Precipitation on Grass Production and Grasshopper Performance in a Northern Mixed Prairie.

Climatic changes are leading to differing patterns and timing of precipitation in grassland ecosystems, with the seasonal timing of precipitation affecting plant biomass and plant composition. No previous studies have examined how drought seasonality affects grasshopper performance and the impact of herbivory on vegetation. We modified seasonal patterns of precipitation and grasshopper density in a manipulative experiment to examine if seasonality of drought combined with herbivory affected plant biomass, nitrogen content, and grasshopper performance. Grass biomass was affected by both precipitation and grasshopper density treatments, while nitrogen content of grass was higher with early-season drought. Proportional survival was negatively affected by initial density, while survival was higher with early drought than with full-season drought. Drought timing affected the outcome, with early summer drought increasing grass nitrogen content and grasshopper survival, while season-long and late-season drought did not. The results support arguments that our knowledge of plant responses to seasonal short-term variation in climate is limited and illustrate the importance of experiments manipulating precipitation phenology. The results confirm that understanding the season of drought is critical for predicting grasshopper population dynamics, as extreme early summer drought may be required to strongly affect Melanoplus sanguinipes (F.) performance.

Rainfall prediction for sustainable economic growth

Agriculture is the backbone of Zimbabwe’s economy with the majority of Zimbabweans being rural people who derive their livelihood from agriculture and other agro-based economic activities. Zimbabwe’s agriculture depends on the erratic rainfall which threatens food, water and energy access, as well as vital livelihood systems which could severely undermine efforts to drive sustainable economic growth. For Zimbabwe, delivering a sustainable economic growth is intrinsically linked to improved climate modelling. Climate research plays a pivotal role in building Zimbabwe’s resilience to climate change and keeping the country on track, as it charts its path towards sustainable economic growth. This paper presents a simple tool to predict summer rainfall using standardized Darwin sea level pressure (SDSLP) anomalies and southern oscillation index (SOI) that are used as part of an early drought warning system. Results show that SDSLP anomalies and SOI for the month of April of the same year, i.e., seven months before onset of summer rainfall (December to February total rainfall) are a simple indicator of amount of summer rainfall in Zimbabwe. The low root mean square error (RMSE) and root mean absolute error (RMAE) values of the proposed model, make SDSLP anomalies for April and SOI for the same month an additional input candidates for regional rainfall prediction schemes. The results of the proposed model will benefit in the prediction of oncoming summer rainfall and will influence policy making in agriculture, environment planning, food redistribution and drought prediction for sustainable economic development. Keywords: sustainable economic growth, standardized Darwin sea level pressure anomalies, southern oscillation index, summer rainfall prediction, Zimbabwe. JEL Classification: Q16, Q25, Q54, Q55, Q58

Avaliação do impacto da desertificação no ambiente e na população do Semiárido brasileiro por meio de uma base de dados geográficos

A região Nordeste do Brasil é marcada fortemente pelas desigualdades regionais apresentando altos índices de analfabetismo, baixa renda, migração para os grandes centros urbanos, exclusão social, entre outros. Além da desigualdade cultural e econômica, a região é afetada com a degradação/desertificação da terra exacerbada por fatores antrópicos. O entendimento das mudanças na paisagem e como essas alterações impactam a vulnerabilidade da população é um desafio, pois essas alterações ocorrem em amplas escalas espaciais e temporais. Assim, o desenvolvimento de uma ferramenta capaz de integrar informações físicas, ambientais e socioeconômicas, em diferentes escalas e resoluções torna-se essencial para a compreensão do processo. Mais importante que o desenvolvimento da ferramenta é saber analisar de forma conjunta as informações geradas. Dessa forma, este trabalho visa descrever a metodologia em desenvolvimento no Sistema de Alerta Precoce contra Seca e Desertificação ”“ SAP, bem como analisar, por meio de cruzamento de informações relacionadas à degradação/desertificação do solo, a vulnerabilidade da população ante a essas alterações. O objetivo é facilitar e agilizar a análise dos tomadores de decisão de maneira a permitir tomadas de decisões em áreas onde ambos os processos estejam ocorrendo de forma mais acelerada.

Roles of plant hormones and anti-apoptosis genes during drought stress in rice (Oryza sativa L.).

We previously identified the rice (Oryza sativa) senescence-associated gene OsSAP which encodes a highly conserved protein involved in anti-apoptotic activity. This novel Bax suppressor-related gene regulates tolerance to multiple stresses in yeast. Here, we show the effects of drought stress on leaf and root tissues of plants over-expressing OsSAP in relation to the levels of phytohormones, abscisic acid (ABA), jasmonic acid (JA), indole-3-carboxylic acid (ICA), gibberellic acid (GA3), and zeatin. Results showed that rice plants over-expressing SAP were tolerant to drought stress compared to wild type and the plants over-expressing AtBI-1, which is a homolog of the human Bax inhibitor-1 in Arabidopsis. ABA and JA levels in OsSAP and AtBI-1 transgenic plants consistently increased up to at least 3 days after drought treatment, whereas lower GA3 levels were recorded during early drought period. Comparison between control and transgenic plants overexpressing anti-apoptosis genes OsSAP and AtBI-1 resulted in different patterns of hormone levels, indicating that these genes are involved in the plant responses to drought stress and present an opportunity for further study on drought stress tolerance in rice and other plant species.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-016-0564-x) contains supplementary material, which is available to authorized users.

Osmotic adjustment of young sugar beets (Beta vulgaris) under progressive drought stress and subsequent rewatering assessed by metabolite analysis and infrared thermography.

The main objective of this work was to provide the chronology of physiological and metabolic alterations occurring under drought and demonstrate how these relate to a phenotypic approach (infrared thermal imaging, IRT). This should provide tools to tailor phenotyping approaches for drought tolerance and underlying metabolic alterations. In the present study, destructive analysis of growth and cell morphology, water status, osmotic adjustment, metabolic changes and membrane damage were combined with non-destructive determination of leaf temperature using infrared thermography (IRT) in 6-week-old sugar beets subjected to progressive drought stress and subsequent rewatering. Different methods were suitable for the characterisation of the dynamic development of distinct stress phases: although IRT allowed detection of initial impairment of transpiration within 1 day of drought stress, destructive methods allowed us to distinguish a phase of metabolic adjustment including redirection of carbon flow into protective mechanisms and a subsequent phase of membrane destabilisation and cellular damage. Only the combination of invasive and non-invasive methods allowed for the differentiation of the complete sequence of physiological changes induced by drought stress. This could be especially beneficial for the selection of phenotypes that are adapted to early drought. During rewatering, sugar beet shoots rapidly re-established water relations, but membrane damage and partial stomatal closure persisted longer, which could have an impact on subsequent stress events. During the onset of secondary growth, taproots required more time to recover the water status and to readjust primary metabolites than shoots.

Early responses of mature Arabidopsis thaliana plants to reduced water potential in the agar-based polyethylene glycol infusion drought model

Drought is one of the most important environmental stressors resulting in increasing losses of crop plant productivity all over the world. Therefore, development of new approaches to increase the stress tolerance of crop plants is strongly desired. This requires precise and adequate modeling of drought stress. As this type of stress manifests itself as a steady decrease in the substrate water potential (ψw), agar plates infused with polyethylene glycol (PEG) are the perfect experimental tool: they are easy in preparation and provide a constantly reduced ψw, which is not possible in soil models. However, currently, this model is applicable only to seedlings and cannot be used for evaluation of stress responses in mature plants, which are obviously the most appropriate objects for drought tolerance research. To overcome this limitation, here we introduce a PEG-based agar infusion model suitable for 6–8-week-old A. thaliana plants, and characterize, to the best of our knowledge for the first time, the early drought stress responses of adult plants grown on PEG-infused agar. We describe essential alterations in the primary metabolome (sugars and related compounds, amino acids and polyamines) accompanied by qualitative and quantitative changes in protein patterns: up to 87 unique stress-related proteins were annotated under drought stress conditions, whereas further 84 proteins showed a change in abundance. The obtained proteome patterns differed slightly from those reported for seedlings and soil-based models.

Drought Priming at Vegetative Growth Stage Enhances Nitrogen‐Use Efficiency Under Post‐Anthesis Drought and Heat Stress in Wheat

AbstractTo study the effects of early drought priming at 5th‐leaf stage on grain yield and nitrogen‐use efficiency in wheat (Triticum aestivum L.) under post‐anthesis drought and heat stress, wheat plants were first exposed to moderate drought stress (drought priming; that is, the leaf water potential reached ca. −0.9 MPa) at the 5th‐leaf stage for 11 days, and leaf water relations and gas exchange rates, grain yield and yield components, and agronomic nitrogen‐use efficiency (ANUE) of the primed and non‐primed plants under post‐anthesis drought and heat stress were investigated. Compared with the non‐primed plants, the drought‐primed plants possessed higher leaf water potential and chlorophyll content, and consequently a higher photosynthetic rate during post‐anthesis drought and heat stress. Drought priming also resulted in higher grain yield and ANUE in wheat under post‐anthesis drought and heat stress. Drought priming at vegetative stage improves carbon assimilation and ANUE under post‐anthesis drought and heat stress and their combination in wheat, which might be used as a field management tool to enhance stress tolerance of wheat crops to multiple abiotic stresses in a future drier and warmer climate.

Experience of inundation or drought alters the responses of plants to subsequent water conditions

Summary The availability of water is often highly variable over the life of a plant in nature, and most plants experience episodic extremes in water scarcity and abundance. The importance of plant plasticity in coping with such experiences is widely recognized, but little is known about how plastic responses to current conditions are affected by prior environmental experiences. Our objectives were to investigate the effects of early inundation or drought on the subsequent responses of plant species to the same, opposite or more favourable conditions. To address these questions, we subjected four invasive and four native herbaceous perennial species from different habitats (xeric, mesic, hydric) to two rounds of hydrological treatments (drought, moderate water, inundation) and analysed the effects of the early treatments on survival and performance (total biomass and relative growth) of individuals in the later treatments. In general, (i) early drought reduced the performance of more species than did early inundation, and decreased the final total mass of all species; (ii) early inundation and early drought did not lead to lower survival immediately or later, but improved the relative growth of survivors across all late conditions; (iii) late drought resulted in the highest mortality and lowest performance after any early treatment. With respect to habitat of origin: (i) early inundation was more beneficial for species from wet habitats than for other species; (ii) species from xeric habitats had the strongest drought tolerance after early drought; (iii) mesic species were more likely to suffer reduced later growth after either inundation or drought experience. Invasive species benefitted more from early inundation than did native species, but native species grew better after experiencing early drought. Results indicate that early exposure to inundation or drought conditions alters how plants respond to later conditions and suggest that exposure to extreme events can induce physiological or morphological changes that improve tolerance for either extreme conditions later. This increased tolerance can be at the cost of poorer performance under more benign conditions. Synthesis. Early inundation or drought experience may be harmful immediately, but can be beneficial for the later growth of plants. The ability of species to utilize early hydrological experiences was associated with the water range of their habitats and whether the species is invasive or native. The ability to modulate future plastic responses may be as important as short‐term plasticity in adapting to temporal environmental heterogeneity. Such ‘metaplasticity’ can optimize current performance, while avoiding the potential costs of maintaining a high degree of plasticity throughout life.

Melatonin enhances cold tolerance in drought-primed wild-type and abscisic acid-deficient mutant barley.

Melatonin is involved in multiple plant developmental processes and various stress responses. To explore the roles of melatonin played as well as its association with abscisic acid (ABA) in a process of drought priming-induced cold tolerance (DPICT), a wild-type barley and its ABA-deficient mutant Az34 counterpart were selected for comparison, in which the effects of melatonin application (either foliarly or rhizospherically) and/or drought priming on the cold tolerance of both types of barleys were systematically investigated. It was demonstrated that the early drought priming induced an increase of endogenous melatonin production, which is not ABA dependent. In addition, exogenously applied melatonin resulted in higher ABA concentration in the drought-primed plants than in the nonprimed plants when exposed to cold stress, indicating that ABA responded in a drought-dependent manner. The interplay of melatonin and ABA leads to plants maintaining better water status. Drought priming-induced melatonin accumulation enhanced the antioxidant capacity in both chloroplasts and mitochondria, which sustained the photosynthetic electron transport in photosynthetic apparatus of the plants under cold stress. These results suggest that the exogenous melatonin application enhances the DPICT by modulating subcellular antioxidant systems and ABA levels in barley.

English

This study was conducted to evaluate the growth and yield stability of cassava mosaic disease (CMD) resistant breeding populations clones against early drought. Field trials were planted using 200 CMD resistant clones and 7 local landraces in a randomised complete block design with 3 replicates at the International Institute of Tropical Agriculture (IITA) station, Sendusu in Namulonge (Central Uganda) during the second rains of 2006 (2006B) and the first rains of 2007 (2007A). The 2007A crop suffered from drought stress in the first 4 months after planting (MAP). Data were taken on the leaf lobe length and width at 6 MAP and plant height at 12 MAP. Harvest was done at 12 MAP during which the number of storage roots per plant and storage root yield were recorded. Data were analysed using the Mann-Whitney U test to compare crop performance between the 2 seasons. The 2006B crop had significantly (P<0.01) longer leaf lobes, taller plant heights, higher number of storage roots per plant and higher storage root yield than the 2007A crop. There was no significant difference in the leaf lobe width. In this experiment, it was observed that the CMD resistant breeding clones were susceptible to early drought and thus it was recommended that selections should be done for higher water use efficiency. Key words: Abscisic acid, Manihot esculenta Crantz, Stomatal conductance, water use efficiency, Uganda.

Early Drought Detection by Spectral Analysis of Satellite Time Series of Precipitation and Normalized Difference Vegetation Index (NDVI)

The time lag between anomalies in precipitation and vegetation activity plays a critical role in early drought detection as agricultural droughts are caused by precipitation shortages. The aim of this study is to explore a new approach to estimate the time lag between a forcing (precipitation) and a response (NDVI) signal in the frequency domain by applying cross-spectral analysis. We prepared anomaly time series of image data on TRMM3B42 precipitation (accumulated over antecedent durations of 10, 60, and 150 days) and NDVI, reconstructed and interpolated MOD13A2 and MYD13A2 to daily interval using a Fourier series method to model time series affected by gaps and outliers (iHANTS) for a dry and a wet year in a drought-prone area in the northeast region of China. Then, the cross-spectral analysis was applied pixel-wise and only the phase lag of the annual component of the forcing and response signal was extracted. The 10-day antecedent precipitation was retained as the best representation of forcing. The estimated phase lag was interpreted using maps of land cover and of available soil water-holding capacity and applied to investigate the difference in phenology responses between a wet and dry year. In both the wet and dry year, we measured consistent phase lags across land cover types. In the wet year with above-average precipitation, the phase lag was rather similar for all land cover types, i.e., 7.6 days for closed to open grassland and 14.5 days for open needle-leaved deciduous or evergreen forest. In the dry year, the phase lag increased by 7.0 days on average, but with specific response signals for the different land cover types. Interpreting the phase lag against the soil water-holding capacity, we observed a slightly higher phase lag in the dry year for soils with a higher water-holding capacity. The accuracy of the estimated phase lag was assessed through Monte Carlo simulations and presented reliable estimates for the annual component.

A general framework for multivariate multi-index drought prediction based on Multivariate Ensemble Streamflow Prediction (MESP)

Summary Drought is among the costliest natural hazards worldwide and extreme drought events in recent years have caused huge losses to various sectors. Drought prediction is therefore critically important for providing early warning information to aid decision making to cope with drought. Due to the complicated nature of drought, it has been recognized that the univariate drought indicator may not be sufficient for drought characterization and hence multivariate drought indices have been developed for drought monitoring. Alongside the substantial effort in drought monitoring with multivariate drought indices, it is of equal importance to develop a drought prediction method with multivariate drought indices to integrate drought information from various sources. This study proposes a general framework for multivariate multi-index drought prediction that is capable of integrating complementary prediction skills from multiple drought indices. The Multivariate Ensemble Streamflow Prediction (MESP) is employed to sample from historical records for obtaining statistical prediction of multiple variables, which is then used as inputs to achieve multivariate prediction. The framework is illustrated with a linearly combined drought index (LDI), which is a commonly used multivariate drought index, based on climate division data in California and New York in the United States with different seasonality of precipitation. The predictive skill of LDI (represented with persistence) is assessed by comparison with the univariate drought index and results show that the LDI prediction skill is less affected by seasonality than the meteorological drought prediction based on SPI. Prediction results from the case study show that the proposed multivariate drought prediction outperforms the persistence prediction, implying a satisfactory performance of multivariate drought prediction. The proposed method would be useful for drought prediction to integrate drought information from various sources for early drought warning.

How does the drought of 2012 compare to earlier droughts in Kansas, USA?

How does the drought of 2012 compare to earlier droughts in Kansas, USA?