Precipitation Deficiency Research Articles

Divergent impacts of seasonal precipitation deficiency on grassland growth in drylands of Central Asia

Abstract Water availability and its timing are essential for determining dryland dynamics, and grasslands in Central Asia are particularly vulnerable to water provided by precipitation. Climate change is projected to alter the seasonal distribution of precipitation patterns and increase the frequency of extreme events. Little is known about the response of grasslands to seasonal precipitation deficiency (PD), especially considering the time lag effect. Here, we evaluated the impacts of PD on grassland growth at the seasonal scale based on the normalized difference vegetation index (NDVI). Our findings showed that grassland growth during spring was mostly affected by PD in arid regions, with PD occurring during the nongrowing season and spring causing mean standardized anomalies (SAs) of −0.83 and −0.54, respectively, for the NDVI. In semiarid and subhumid regions, summer PD caused not only the largest negative response in summer (with SAs of −0.94 and −0.80 for semiarid and subhumid regions, respectively) but also in autumn (−0.80 and −0.74). PD in autumn had a less adverse effect on grassland growth. The divergent seasonal responses primarily stemmed from shifts in the dominant factors influencing grassland growth across seasons. PD reduced soil moisture in spring and summer, which in turn affected grassland growth. However, summer PD affected autumn grassland growth primarily through the carryover effect. Our results highlighted the importance of the timing of PD and suggested that precipitation in the previous season should receive more attention when considering the relationship between vegetation and precipitation at the seasonal scale.

Scarcity of P-fertilisers: Humic-complexed phosphate as an adaptive solution for wheat and maize under rainfed conditions

The current context of food security and global geopolitical crises calls for proactive efforts to seek adaptive strategies for limited resources in agriculture. The production of phosphatic-based fertilisers has caused a substantial depletion of natural phosphorus (P) reserves, raising concerns about price increases due to the growing demand for P. The aim of the study is to assess whether the use of liquid organo-mineral P-complexes can be an adaptive strategy to address the issue of the limited P-fertiliser resource. A complete randomised block design was implemented with three replicates, spanning two contrasting cropping seasons under a Mediterranean climate with reduced tillage and rainfed conditions. The study aimed to assess the response of a durum wheat–maize rotation to various rates of liquid organo-mineral P-complexes (humic-complexed phosphate; HCP) in comparison to granular triple superphosphate (TSP). The evaluation focused on several parameters, including P availability, plant architecture, dry matter accumulation, grain yield and yield components and P use efficiency (PUE) for both durum wheat and maize. The results revealed that applying HCP at a rate of 4 or 8 kg ha−1 increased soil P availability on average by 66% and 144%, respectively, compared to the control (no P-fertilisation), although a significant interaction with the monitoring year emerged. For wheat, applying HCP at a rate of 8 kg ha−1 of P resulted in higher grain yield (+15%), protein content (+0.9%) and P uptake (+48%) than the control on average considering both monitoring years. In the season characterised by favourable rainfall patterns, the application of HCP at 5 or 10 kg ha−1 of P for maize showed similar effects in terms of soil P availability, dry matter accumulation, grain yields and PUE. Conversely, in the season marked by a deficiency in summer precipitation, low PUE for maize was observed for HCP fertilisers, although they remained positive, unlike the case of TSP. Using HCP in conservation agriculture appears promising as an adaptive solution to address P-fertiliser scarcity, especially amid food security challenges and global crises. However, further studies are required to validate these findings in diverse pedo-climatic contexts and cropping systems.

Relationship of ENSO and Standardized Precipitation Index (SPI) to Characterize Drought at Different Locations of Punjab, India

Drought is generally considered as a deficiency in precipitation over an extended period usually a season or more. It is a natural hazard that differs from other hazards since it has a slow onset, evolves over months or even years and its severity is often difficult to determine. Standardized Precipitation Index (SPI) is a widely used index to characterize drought on a range of timescales. In this study SPI was calculated annually and season (Kharif and Rabi) wise to correlate drought with ENSO events at different locations of Punjab viz. Amritsar, Ballowal Saunkhri, Bathinda, Ludhiana and Patiala. The historical data of rainfall for different locations of Punjab viz. Amritsar (1971-2017), Ballowal Saunkhri (1984-2018), Bathinda (1971-2018), Ludhiana (1971-2018) and Patiala (1971-2018) were collected from the Department of Climate Change and Agricultural Meteorology, PAU, Ludhiana and Met Centre, India Meteorological Department, Chandigarh. It was found that at all the locations very strong El Nino of 1997-98 resulted in above normal rainfall. Drought like conditions was observed during El Nino years as value of SPI was negative but with few exceptions. The SPI values were positive during La Nina and neutral years. Droughts during kharif season were found to be more related to El Nino years compared to La Nina years.

CLIMATIC FACTORS CHARACTERIZING THE MOISTURE SUPPLY OF THE TERRITORY AND THEIR EFFECT ON THE QUALITY INDICATORS OF GRAPES

The study of scientific problem, to which this research is devoted, is due to planetary climate change, manifested in an increase in the average annual air temperature, rapid changes in winter and summer temperatures, and a lack of precipitation.
 For today, there is a serious problem of adapting plants to climate change due to an increase in water deficiency in many regions of the world. Climate change creates significant uncertainty in the potential adaptability of grape plants, as well as in the prospects for viticulture development in general.
 The study and generalization of territorial distribution of climatic factors that characterize a particular region, as well as their effect on the quality characteristics of raw materials and finished products, are attractive from the point of better understanding and forecasting the potential impact on agricultural systems. The obtained data consumption will allow improving the forecast of climate change consequences in the medium term, and in relation to particular terroirs.
 The goal is to study the effect of climatic factors that characterize the moisture supply of the territory on the quality indicators of grapes.
 Materials and methods. The objects of the study were grapes of white and red cultivars, different in agroecological aspect, and growing in micro regions of Crimea. To identify the effect of factors characterizing the moisture supply of the territory on the quality indicators of raw materials for winemaking products, the amount of precipitation from the beginning of growing season to the harvesting, the amount of precipitation for the last month before harvest, and hydrothermal coefficient of Selyaninov were selected. The assessment of grapes was carried out according to the indicators of carbohydrate-acid complex (mass concentration of sugars, titratable acids, pH value, profile of organic acids), as well as the glucoacidimetric indicator revealing the degree of grape ripeness.
 Results and conclusion. Climatic factors characterizing the moisture supply of viticultural and winemaking regions of Crimea were assessed. The studies carried out made it possible to reveal variations in the concentration of carbohydrate-acid complex components depending on the changing ability of environmental factors. A significant precipitation deficiency was observed on the Peninsula. According to the value of hydrothermal coefficient of Selyaninov (did not exceed 1), most of the territory was classified as an arid or very arid zone. A correlation between the hydrothermal coefficient and mass concentration of grape sugars (r=-0.63) was established for red grapevine cultivars. The data obtained indicate that an increase in the amount of precipitation during growing season contributes to a moderation of sugar accumulation in grapes. Similar pattern was not established for white grapevine cultivars. There was a direct correlation of the mass concentration of malic acid on the amount of precipitation in the last month before harvest (r=0.78).

Toward a Redefinition of Agricultural Drought Periods—A Case Study in a Mediterranean Semi-Arid Region

Drought is a powerful natural hazard that has significant effects on ecosystems amid the constant threats posed by climate change. This study investigates agricultural drought in a semi-arid Mediterranean basin through the interconnections among four indices: precipitation (meteorological reanalysis), vegetation development, thermal stress, and soil water deficit (remote sensing observations). While drought seems to be a clear concept with effective assessment tools (e.g., SPI and SPEI), the definition of drought periods is blurrier. This article examines the main drivers of agricultural drought, precipitation, soil moisture deficit, incipient vegetation development, and rising soil surface temperature. Their temporal connections in various agrosystems of the basin and the determination of drought periods by revisiting the run theory were investigated. The Pearson correlations at different spatial scales showed a medium to low level of agreement between the indices, which was explained by the geographical heterogeneity and the climatic variability between the agrosystems within the basin. It was also shown that the cascade of impacts expected from lower precipitations was revealed by the cross-correlation analysis. The connection between precipitation deficit and vegetation remains significant for at least one month for most pairs of indices, especially during drought events, suggesting that agricultural drought spells can be connected in time through the three or four selected indices. Short-, mid-, and long-term impacts of precipitation deficiencies on soil moisture, vegetation, and temperature were revealed. As expected, the more instantaneous variables of soil moisture and surface temperature showed no lag with precipitation. Vegetation anomalies at the monthly time step showed a two-month lag with a preceding effect of vegetation to precipitation. Finally, the determination of drought events and stages with varying thresholds on the run theory showed large variability in duration, magnitude, and intensity according to the choice of both normality and dryness thresholds.

An assessment of historical short-time precipitation deficiency in eastern Slovakia and northern Serbia according to the SPI-3

An assessment of historical short-time precipitation deficiency in eastern Slovakia and northern Serbia according to the SPI-3

Remote sensing-based drought hazard monitoring and assessment in a coastal plain: A principal component approach

Accurate drought information is essential for preventing agricultural and societal losses. The indicators of how severe a drought is the deficiency in precipitation, soil moisture, and vegetation stress. The indicators were evaluated using the Precipitation Condition Index (PCI), Vegetation Condition Index (VCI), and Temperature Condition Index (TCI).The indices were combined using Principal Component Analysis to create the Synthetic Drought Index (SDI) for the evaluation of drought severity. The indices were estimated using multi-source remote sensing data from the Tropical Rainfall Measuring Mission (TRMM) and Operational Land Imager (OLI) of various years. Temporal analysis showed that the district is drought-prone and deficiency of 65% of precipitation in northeast monsoon of 2016 and below average non-monsoon rainfall in 2017, caused drought and affected 223.5 Km2 in 2017. Below average precipitation in northeast monsoon of 2018 and below average non-monsoon rainfall in 2019, caused drought and affected 423 Km2 in 2019. The northeast coastal regions of Ottapidaram, Thoothukudi, and Vilathikulam taluks of the district were more severely prone to drought. Failure of monsoon is the root cause of water deficit in water bodies. The semi-arid coastal climate accelerates the evaporation of water in water bodies and causes soil moisture deficit that leads to drought in the coastal district. A sequential evaluation of this index can be used to identify the onset of drought and mitigate the effect of drought.

How 2022 extreme drought influences the spatiotemporal variations of terrestrial water storage in the Yangtze River Catchment: Insights from GRACE-based drought severity index and in-situ measurements

Under global warming, extreme climatic events frequently occurred worldwide such as extreme drought and heavy flood. Analysis of drought and flood spatiotemporal evolution and physical mechanism is of great significance for future disaster warning and mitigation. In 2022, the Yangtze River Catchment (YRC) experienced an extreme drought, which profoundly affected the regional economy, ecological environment and anthropogenic activities. In this study, we quantified the spatiotemporal characteristics of terrestrial water storage anomalies (TWSA) response to this severe drought event using Gravity Recovery and Climate Experiment-based drought severity index (GRACE-DSI), with the inspection of hydrological model and in-situ measurements. The results showed that the 2022 YRC drought first occurred in July at the upstream and midstream, then spread to downstream and finally occupied almost the whole YRC in August and ∼ 94% of the YRC in September. The effectiveness of GRACE-DSI for drought monitor can be validated by in-situ hydrological and meteorological observations. Good correlations among El Niño-Southern Oscillation (ENSO), precipitation anomalies (PA), and TWSA were found, demonstrating the regional atmospheric circulation anomaly was the driving factor of this extreme drought event, which triggered the changes in precipitation further to influence the pattern of terrestrial water storage. The consecutive La Niña events induced the extension of western Pacific subtropical high (WPSH) and Iranian high, the precipitation deficiency in 2022 summer declined by ∼ 46% and ∼ 36% compared to 2020 and 2021 respectively, which was the main cause of the extreme drought.

Testing the annual rainfall dispersion in Chaiyaphum, Thailand, by using confidence intervals for the coefficient of variation of an inverse gamma distribution

In Thailand, droughts are regular natural disasters that happen nearly every year due to several factors such as precipitation deficiency, human activity, and the global warming. Since annual rainfall amount fits an inverse gamma (IG) distribution, we wanted to try testing annual rainfall dispersion via the coefficient of variation (CV). Herein, we propose two statistics for testing the CV of an IG distribution based on the Score and Wald methods. We evaluated their performances by means of the Monte Carlo simulations conducted under several shape parameter values for an IG distribution based on empirical type I error rates and powers of the tests. The simulation results reveal that the Wald-method test statistic performed better than the Score-method one in terms of the attained nominal significance level, and is thus recommended for analysis in similar scenarios. Furthermore, the efficacy of the proposed test statistics was illustrated by applying them to the annual rainfall amounts in Chaiyaphum, Thailand.

Influence of climatic conditions on forest fires in Central Yakutia

The activity of forest fires has greatly increased in recent years in Central Yakutia. This can lead to the radical transformation of permafrost landscapes and their degradation. This study aimed to determine the effects of climatic conditions on forest fire activity in this area. We analyzed data on air temperature and rainfall during the fire season from 2000 to 2020. The total annual burned areas have noticeably increased since the 2000s. Forest fires covered an area of more than a million hectares in 2002 and 2011. This trend was associated with climate change. The mean annual air temperature in Yakutsk increased by approximately 2 °C from 2000 to 2020, while the summer precipitation decreased. Both air temperature and the amount of precipitation during the fire season affect the accumulation of dry combustible material under the forest canopy, which determines whether favorable conditions are created for the spread of forest fires over large areas. We showed which climatic conditions are typical for periods of high and low fire activity. We analyzed the climatic conditions of certain years with the maximum and minimum burnt areas. Fire activity in the study area depends on the climatic conditions at the beginning of the fire season. High fire activity occurs at very high air temperatures; however, the predominant role is the deficiency of precipitation. The study of the dependence of forest fire activity on climatic conditions is important for estimating the consequences caused by climate change in permafrost landscapes.

Quantitative attribution of vertical motions responsible for the early spring drought conditions over southeastern China

The interannual variability and long-term trend of the drought conditions over southeastern China during early spring (from February to April) are investigated by analyzing the standardized precipitation evapotranspiration index in 1979–2020. Results from an attribution analysis show that precipitation deficiency and atmospheric water demand contributes about 96.5 and 6.7% to the drought conditions on interannual time scale, and about 72.8 and 22.3% to the long-term trend, respectively. The precipitation deficiency is primarily contributed by moisture divergence via the descending anomalies throughout the troposphere over southeastern China. A further diagnosis with the omega equation reveals that the descending anomalies are dominated by the strong negative zonal vorticity advection in the upper troposphere and the enhanced meridional cold advection throughout the troposphere. They are controlled by a barotropic anomalous anticyclone over the eastern Tibetan Plateau and an anomalous cyclone over the western North Pacific. Non-negligibly, the contribution of potential evapotranspiration to the drying trend in early spring over southeastern China is about four times larger than that to the interannual variability. Given that potential evapotranspiration may increase in a warming climate, it may be critical for the change in drought conditions in future. This study serves as a basis for fully understanding the severity of recent droughts and for model simulation of the drought conditions over southeastern China.

Hydrologic evaluation of the global precipitation measurement mission over the U.S.: Flood peak discharge and duration

In recent years, a great amount of research has been done towards evaluating precipitation data generated by satellites, but less has focused on how these estimates and their uncertainties manifest further into the water cycle. In this study, ten years of satellite-based and ground-based radar data are used as forcings for a distributed hydrologic model across the Continental United States. They are compared using a methodology designed to assess the flood signals and characteristics generated by the model. By focusing on how well the model reproduces flood characteristics rather than fits traditional bulk statistics, this research provides robust insights into satellite precipitation deficiencies. It is found that satellite data has greater success at resolving lower magnitude flood events while tending to generate floods of longer durations. Additionally, flood managers should note that satellites tend to generate floods that characteristically both begin earlier and end later than the ground radar reference. Subsequent research is recommended into other satellite data products in order to better understand these discrepancies and mitigate or plan for them in the future. Plain Language SummaryIn recent years, satellites have been increasingly used to provide valuable insights on rainfall across the globe, especially in locations where radars are unable to be installed on the ground. By nature, however, the rainfall data provided by satellites has uncertainties. Large amounts of research has gone into the difference in accuracy between satellite radar and ground references, but less has focused on how these differences impact flood simulations, respectively. In this study it was found that the rainfall data from satellites tends to predict floods that are more severe (have higher magnitudes), last longer (have longer durations), and have different timings (start earlier and end later) than the reference. It is also found that satellites struggle with predictions involving extreme rainfall values. Further research is suggested to better understand these issues, as well as compare against other forms of satellite rainfall data.

Southeast China Extreme Drought Event in August 2019: Context of Coupling of Midlatitude and Tropical Systems

Abstract An extreme drought occurred over Southeast China (SEC) in August 2019. We demonstrate synergistic effects of midlatitude and tropical circulation on this extreme event and highlight the impacts of the coupling and locking of two cyclones at different latitudes, which are otherwise ignored. We propose the relaying roles of the Tibetan Plateau (TP) and western North Pacific in connection with the tropical convection and SEC precipitation. The equivalent-barotropic anticyclone over the TP and lower-tropospheric cyclone over the western North Pacific both resulted from the positive Indian Ocean dipole and El Niño Modoki. The equivalent-barotropic cyclone over Northeast China originated from the dispersion of Rossby waves upstream along the subtropical waveguide associated with the North Atlantic tripole sea surface temperature anomaly pattern and the Rossby wave response to the TP precipitation deficiency. Further, they jointly contributed to this drought by inducing strong northerly wind anomalies in the entire troposphere over East China. These anomalous northerly winds led to decreased warm moisture from the south and substantial sinking motions, which inhibited the occurrence of the SEC local convection and precipitation. The SEC precipitation is closely related to convection over the Maritime Continent from a climate perspective. This relationship is verified by observations, linear baroclinic model experiments, and general circulation model sensitivity experiments with and without the TP, in which precipitation anomalies over the southern TP and Philippine Sea play important bridge roles. The results will advance the prediction of the SEC extreme drought events.

Органическое земледелие в лесостепи западной Сибири: оценка повторяемости атмосферных засух на основе SPI

This paper presents the findings of a study to assess the recurrence of moisture/drought conditions on the territory of the forest-steppe zone of Western Siberia for the period from 1971 to 2021. The degree of moistening was investigated on the basis of the Standardized Precipitation Index (SPI). Calculations were made for 4 areas (Altai Territory, Kemerovo, Novosibirsk and Omsk regions) with meteorological stations located on the territory of the forest-steppe zone of Western Siberia. In the studied areas, it was found that the drought conditions of different categories were manifested with a certain periodicity. SPI categories "moderately dry", "severely dry" and "extremely dry" for the studied period in May-July in Altai Territory account for 15,68% of years, in Novosibirsk Region for 13,72%, in Kemerovo Region for 19,6% and in Omsk Region for 13,72% of years. Local manifestation of extreme droughts for the time interval under study in the forest-steppe zone of Western Siberia was observed 7 times. Frequency of occurrence of deficiency of atmospheric precipitation during a part of vegetative period from May till July in territories of subjects in forest-steppe zone of Western Siberia is on the average 15,68%. The years with atmospheric precipitation shortage during the 51-year period in May accounted for 6 to 10 years, and 6 to 8 years in June. For Altai Territory, Novosibirsk and Kemerovo regions in the dynamics revealed trends in improving wetting conditions, characteristic both for most of the growing season of May-July, and separately for May and June. For territory of the Omsk region the trend indicating decrease in quantity of atmospheric precipitation in June is established. Frequency of occurrence of the dry events connected with deficiency of atmospheric precipitation remains high enough (once in 7-8 years). The results of studies on the degree of moisture/drought of the territory, carried out by SPI calculations, can be used for risk analysis and assessment of the effectiveness of crop production, as well as for the development and adaptation of farming systems, including organic agriculture to changing climatic conditions, where the role of natural factors in the crop production process becomes much more prominent. Keywords: ATMOSPHERIC DROUGHT, STANDARDIZED PRECIPITATION INDEX, SPI, FOREST-SEPHERE ZONE, WESTERN SIBERIA

Mechanisms and physical-empirical prediction model of concurrent heatwaves and droughts in July–August over northeastern China

Concurrent heatwaves and droughts that occur over northeastern China (NEC) bring severe threats to human lives and crop production. Despite the great efforts taken in previous studies, realistic prediction of these concurrent extreme events remains a challenge. In the present study, a probability-based index that simultaneously considers precipitation deficiency and high temperature is calculated to represent concurrent heatwaves and droughts in July–August over NEC. Based on this index, the characteristics of concurrent heatwaves and droughts over NEC in July–August are investigated using the year-to-year increment approach. The results indicate that the occurrence of concurrent heatwaves and droughts over NEC is closely related to the Polar-Eurasian teleconnection pattern and the Pacific-Japan teleconnection pattern. Further analyses indicate that the sea ice content in the Barents Sea in March (SICBS), the La Niña-like sea surface temperature (SST) in February (SST-PC1), and the northwestern Siberia soil moisture in April (SM) are coincidently linked to the two teleconnection patterns mentioned above. Based on their corresponding physical mechanisms, these three independent predictors are chosen to construct a physical-empirical prediction model for the prediction of concurrent heatwaves and droughts over NEC. Results suggest that this physical-empirical prediction model performs well with a high correlation coefficient and a low root mean squared error between the observed and predicted concurrent heatwaves and droughts over NEC during the period of 1979–2018. Moreover, the cross-validation test and independent hindcasts both suggest that the physical-empirical model proposed in the present study with the three independent predictors has good prediction skills.

A Multivariate Drought Index for Seasonal Agriculture Drought Classification in Semiarid Regions

Drought assessment in any region primarily hinges on precipitation deficiency, which is subsequently propagated to various components and sectors, leading to different drought types. In countries such as India, an intricate relationship between various governing factors, drought types, and their quantification methodologies make it elusive to timely initiate government relief measures. This also prevents comprehensive inclusion of the integrated effect of the principal drivers of drought, resulting in ambiguous categorization of severity, where groundwater storage variability is often neglected despite its significant role in irrigation. Here, we developed a multivariate Joint Drought Index (JDI) combining satellite and model-based standardized indices of precipitation and evapotranspiration (SPEI), soil moisture (SSI), groundwater (SGI), and surface runoff (SRI) with different temporal scales by employing two robust methods, principal component analysis (PCA) and Gaussian copula, and applied the index to highly drought-prone Marathwada region from central India. Our novel approach of using different scale combinations of integrated indices for two primary seasons (Kharif and Rabi) provides more realistic drought intensities than multiple univariate indices, by incorporating the response from each index, representing the seasonal drought conditions corroborating with the seasonal crop yields. JDI, with both methods, successfully identified two major drought events in 2015 and 2018, while effectively capturing the groundwater drought. Moreover, despite the high correlation between JDI using PCA and copula, we observed a significant difference in the intensities reported by these methods, where copula detected exceptional drought conditions more frequently than PCA. JDI effectively detected the onset, duration, and termination of drought, where the improved accuracy of drought detection can play a critical role in policy formation and socioeconomic security of the related stakeholders. Seasonal agriculture drought categorization for holistic quantification of drought conditions as presented in this study should provide broad methodological implications on drought monitoring and mitigation measures, especially for agriculture-dominated regions in semiarid climates.

Drought index predictability for historical and future periods across the Southern plain of Nepal Himalaya.

Drought episodes across the Himalayas are inevitable due to rapidly increasing atmospheric temperatures and uncertainties in rainfall patterns. Tarai of Nepal is a tropical region located in the foothills of the Central Himalaya as a country's food granary with a contribution of over 50% to the entire country's agricultural production. However, there is a lack of detailed studies exploring the spatiotemporal occurrence of drought in these regions under the changing climate. In this study, we used the ensemble of nine climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) under two shared socio-economic pathways (SSPs), namely SSP245 (an intermediate development pathway) and SSP585 (a high development pathway), to assess anticipated drought during the mid-century. We used bias-corrected gridded data from the Worldclim to project drought events by the end of the mid-century based on the historical period (1989-2018). We computed historical and projected Thornthwaite moisture index (TMI) to evaluate soil moisture conditions on a seasonal scale for the Tarai region's Eastern, Central, and Western parts. The model ensemble projected a significant increase in precipitation and temperature for the entire Tarai by the end of mid-century. However, the winter and spring seasons are projected to suffer precipitation deficiency and a temperature rise. Our results indicated that the Eastern Tarai would likely experience a decrease in winter precipitation. We emphasize that the presented spatiotemporal pattern of the MI will be instrumental in addressing the irrigation facility's needs, choice, and rotation of crops under the changing climate scenarios and in improving our mitigation measures and adaptation plans for sustainability of the agriculture in drought-prone areas.

Proportional odds model for identifying spatial inter-seasonal propagation of meteorological drought

Drought is probably the most multifaceted environmental disaster that results from a precipitation deficiency. It perhaps has directly and indirectly potential effects on people's lives, the economy, and other environmental resources worldwide. However, for reducing the potential negative impacts of drought, the understanding and information about seasonal drought frequency and persistence are crucial for drought early warning and mitigations policies. Therefore, the current research examines the selected stations' seasonal meteorological drought frequency and persistence. For this purpose, ordinal outcomes of the current research are modelled under the set of cumulative Logit Models (CLM). The estimation of the CLM is made from the logit link function. Further, the Brant Test (BT) is used to check the parallel line assumptions. The BT substantiates that the odds ratios are the same across the several drought classes. Thereby the POM is a ubiquitous choice for the current analysis. Therefore, the Proportional Odds Model (POM) is utilized to compute the odds and Probability of Drought Persistence (PDP) in varying seasons (March, April, May (Spring); June, July, August (Summer); September, October, November (Autumn); December, January, February (Winter). Further, Standardized Precipitation Index (SPI) for a certain time scale (i.e. three-month time scale SPI-3) is mainly utilized in POM. Amid SPI and various seasons, the relationship is found significant at a 5% significance level in various stations, including Murree, Rawalpindi, Sialkot, Sargodha, Faisalabad, Bahawalnagar, Bahawalpur, Mianwali, Jhelum Multan, Khanpur, and Lahore. The potential of the current research is substantiated by twelve meteorological stations in a certain province of Punjab, Pakistan. The current research outcomes provide the direction to dynamically identify the spatial interseasonal propagation of meteorological drought. Moreover, the obtained results can be helpful in making useful policies for the early warning system, drought risk assessment, and management, and formulating the drought-reducing plans.

Evaluation of Hydropower Generation and Reservoir Operation under Climate Change from Kesem Reservoir, Ethiopia

Climate changes significantly cause the precipitation deficiency and in turn reduce the inflow amount in reservoir affecting hydroelectric power generation. The primary objective of this study was to evaluate hydropower generation and reservoir operation under climate change from Kesem reservoir. Recent Representative Pathway (RCP) scenarios were used to evaluate the impact of climate change on power generation. Power transformation equation and variance scaling approach were amalgamated to adjust the bias correction of precipitation and temperature, respectively. Bias, root mean square error, and coefficient of variation were used to check the accuracy of projected rainfall. The base and future precipitation, temperature, and evaporation trend was analysed using the Mann–Kendall test. The flow calibration and validation were carried out by the Hydrologic Engineering Center-Hydrologic Modelling System (HEC-HMS), and hydropower generation was evaluated with reservoir simulation model (MODSIM 8.1) under climate scenarios. The performance of the model was found good with Nash–Sutcliffe coefficient (NSE) of 0.72 and coefficient of determination (R2) of 0.73 for calibration and NSE of 0.74 and R2 of 0.75 for validation. Projected future climate scenarios predicted increasing and decreasing trend of temperature and precipitation, respectively. For RCP4.5 climate scenario, the average energy generation is likely to decrease by 0.64% and 0.82% in both short-term (2021–2050) and long-term (2051–2080), respectively. In case of RCP8.5 climate scenario, the average energy generation will be decreased by 1.06% and 1.35% for short-term and long-term, respectively. Remarkable reduction of energy generation was revealed in RCP8.5 with relation to RCP4.5 scenario. This indicates that there will be high energy fluctuation and decreasing trend in the future energy generation. The research finding is crucial for decision-makers, power authorities, governmental and nongovernmental organizations, and watershed management agencies to take care for sustainability in the future hydropower generation in the Kesem reservoir.

Effect of Different Watering Regimes on Olive Oil Quality and Composition of Coratina Cultivar Olives Grown on Karst Soil in Croatia.

Croatian islands are olive growing areas characterized by poor conditions for olive trees because of karst soil and a precipitation deficiency. Under these conditions, irrigation is a very important factor for constant olive oil production. This paper aims to investigate the effects of different watering regimes on quantity, sensory and chemical quality and composition of Coratina cv. olive oil obtained from trees grown on ameliorate karst soil during two harvesting years. Olive trees were subjected to rainfed conditions and three different irrigation treatments (T1—deficit irrigation representing the usual producer’s practice, T2—regulated deficit irrigation in respect to phenological stages, T3—full irrigation). Irrigation treatments increased oil yield compared to rainfed conditions (T1 + 58%, T2 + 66% and T3 + 74%, representing average values for both studied years). All olive oil samples were of extra quality. Irrigation led to a decrease in carotenoids, volatiles, polyunsaturated fatty acids and linolenic acid contents, with no difference found among irrigation treatments. Total phenols and secoiridoids concentration was not affected by irrigation, indicating that similar oil quality could be achieved with less demand on the water supply. Obtained results could help producers to define a suitable irrigation management in particular conditions of ameliorate karst.