Periods Of Water Scarcity Research Articles

KOHONEN NEURAL NETWORKS FOR RAINFALL-RUNOFF MODELING: CASE STUDY OF PIANCÓ RIVER BASIN

The existence of long and reliable streamflow data records is essential to establishing strategies for the operation of water resources systems. In areas where streamflow data records are limited or present missing values, rainfall-runoff models are typically used for reconstruction and/or extension of river flow series. The main objective of this paper is to verify the application of Kohonen Neural Networks (KNN) for estimating streamflows in Piancó River. The Piancó River basin is located in the Brazilian semiarid region, an area devoid of hydrometeorological data and characterized by recurrent periods of water scarcity. The KNN are unsupervised neural networks that cluster data into groups according to their similarities. Such models are able to classify data vectors even when there are missing values in some of its components, a very common situation in rainfall-runoff modeling. Twenty two years of rainfall and streamflow monthly data were used in order to calibrate and test the proposed model. Statistical indexes were chose as criteria for evaluating the performance of the KNN model under four different scenarios of input data. The results show that the proposed model was able to provide reliable estimations even when there were missing values in the input data set.

KOHONEN NEURAL NETWORKS FOR RAINFALL-RUNOFF MODELING: CASE STUDY OF PIANCÓ RIVER BASIN

The existence of long and reliable streamflow data records is essential to establishing strategies for the operation of water resources systems. In areas where streamflow data records are limited or present missing values, rainfall-runoff models are typically used for reconstruction and/or extension of river flow series. The main objective of this paper is to verify the application of Kohonen Neural Networks (KNN) for estimating streamflows in Piancó River. The Piancó River basin is located in the Brazilian semiarid region, an area devoid of hydrometeorological data and characterized by recurrent periods of water scarcity. The KNN are unsupervised neural networks that cluster data into groups according to their similarities. Such models are able to classify data vectors even when there are missing values in some of its components, a very common situation in rainfall-runoff modeling. Twenty two years of rainfall and streamflow monthly data were used in order to calibrate and test the proposed model. Statistical indexes were chose as criteria for evaluating the performance of the KNN model under four different scenarios of input data. The results show that the proposed model was able to provide reliable estimations even when there were missing values in the input data set.

Two Mediterranean irrigation communities in front of water scarcity: A comparison using satellite image time series

Although a number of studies have analysed the methods to monitor crop water needs, the integration of phenological dynamics and irrigation using water stored in reservoirs has received little attention. This study is an example of such analysis applied to two irrigation communities (IC) located in a Spanish Mediterranean area, one with less water resources than the other, which it was carried out between 2002 and 2008. These years comprised periods of water surplus and water scarcity including the 2007–2008 drought considered by the Catalan public water authority the worst since 1944. The dynamics of maize, alfalfa, fruit trees and poplars were analysed using greenness and wetness extracted from remote sensing data. A statistical analysis was applied in order to find out the relationship between crop wetness and stored water. Results show that the IC used two methods for water-saving: crop substitution, by decreasing the area of maize, and timing the crop cycle, delaying or advancing sowing depending on water availability. In conclusion although one IC is drier in rainfall terms than the other, a similar crop wetness status was detected and no difference was observed between periods of water scarcity and water surplus.

Energy consumption for crop irrigation in a semiarid climate (south-eastern Spain)

This paper analyses the water-energy nexus in irrigation districts (IDs) under the semi-arid conditions of south-eastern Spain. Three IDs supplied by different water sources and subjected to water scarcity over time were studied throughout a 10-year period (2002–2011). A set of performance indicators was selected to characterise water and energy relationships at three management levels: basin, irrigation district, and farm. Basin level was the largest energy consumer, representing 71–82% of the annual total consumption, which ranged from 0.95 to 1.55 kWh m−3. Basin energy consumption increased depending on the water source as follows: surface water, recycled water, groundwater, external water transfer, and desalinated brackish water. ID level involved 12–15% of the annual total consumption. The highest values were attained in periods of water scarcity, when the available sources were those with higher energy requirements. ID modernisation resulted in slight decreases in energy consumption at that level. At farm level, energy consumption was lacking when farmers took advantage of the pressure head in the ID distribution network, whereas it was from 0 to 0.19 kWh m−3 when the available pressure head was lost. Finally, water and energy productivities by the main crops were analysed.

Real Time Drought Forecasting System for Irrigation Management

In recent years frequent periods of water scarcity have enhanced the need to use water more carefully, even in European areas traditionally rich of water such as the Po Valley in northern Italy. In dry periods the problem of water shortage can be enhanced by conflictual use of water such as irrigation, industrial and power production (hydroelectric and thermoelectric). Further, over the last decade the social perspective on this issue is increasing due to possible impacts of climate change and global warming scenarios which come out from the last IPCC Report. The increased frequency of drought periods has stimulated the improvement of irrigation and water management.In this study we show the development and implementation of the real-time drought forecasting system Pre.G.I., an Italian acronym that stands for “Hydro-Meteorological forecast for irrigation management”.The system is based on ensemble prediction at long range (30 days) with hydrological simulation of water balance to forecast the soil water content in field parcels over the Consorzio Muzza basin. The studied area covers 74,000ha in the middle of the Po Valley, near the city of Lodi.The hydrological ensemble forecasts are based on 20 meteorological members of the non-hydrostatic WRF-ARW model with 30 days as lead-time, provided by Epson Meteo Centre, while the hydrological model used to generate soil moisture simulations is the rainfall-runoff distributed FEST-WB model, developed at Politecnico di Milano.The hydrological model was validated against measurements of latent heat flux and soil moisture acquired by an eddy-covariance statio*n. Reliability of the forecasting system and its benefits was assessed on some cases-study occurred in the growing season of 2012.

Households' coping strategies for climate variability related water shortages in Oke-Ogun region, Nigeria

This paper identifies types of coping strategies that are available during water supply shortages to households in Oke-Ogun, Nigeria; investigates the adequacy and effectiveness of coping options and identifies why different population group prefer one particular coping strategy over another. This work also investigates how household socioeconomic status influence the choice of coping strategies during water supply shortages in local communities that do not have formal water utilities. Data was collected via site visits to three local communities in the region, a household survey of 397 respondents, key-informant interviews and focus group discussions. Observed and perceived trends of climate indicate variability with impacts on drying of wells which are the main water supply sources almost immediately after the wet season. During periods of water scarcity, most households combined multiple coping strategies. Yet, 90% of the participating households indicated that available coping strategies are not adequate. Households in traditional compounds rely more on behavioural coping options while households in newer planned neighbourhoods depend on technical coping options. The choice of hard coping options depends on households' socioeconomic characteristics with income as the most influential factor.

A novel stress-induced sugarcane gene confers tolerance to drought, salt and oxidative stress in transgenic tobacco plants.

BackgroundDrought is a major abiotic stress that affects crop productivity worldwide. Sugarcane can withstand periods of water scarcity during the final stage of culm maturation, during which sucrose accumulation occurs. Meanwhile, prolonged periods of drought can cause severe plant losses.Methodology/Principal FindingsIn a previous study, we evaluated the transcriptome of drought-stressed plants to better understand sugarcane responses to drought. Among the up-regulated genes was Scdr1 (sugarcane drought-responsive 1). The aim of the research reported here was to characterize this gene. Scdr1 encodes a putative protein containing 248 amino acids with a large number of proline (19%) and cysteine (13%) residues. Phylogenetic analysis showed that ScDR1is in a clade with homologs from other monocotyledonous plants, separate from those of dicotyledonous plants. The expression of Scdr1 in different varieties of sugarcane plants has not shown a clear association with drought tolerance.Conclusions/SignificanceThe overexpression of Scdr1 in transgenic tobacco plants increased their tolerance to drought, salinity and oxidative stress, as demonstrated by increased photosynthesis, water content, biomass, germination rate, chlorophyll content and reduced accumulation of ROS. Physiological parameters, such as transpiration rate (E), net photosynthesis (A), stomatal conductance (gs) and internal leaf CO2 concentration, were less affected by abiotic stresses in transgenic Scdr1 plants compared with wild-type plants. Overall, our results indicated that Scdr1 conferred tolerance to multiple abiotic stresses, highlighting the potential of this gene for biotechnological applications.

Using water residency time to enhance spatio‐temporal connectivity for conservation planning in seasonally dynamic freshwater ecosystems

SummaryAddressing spatial connectivity in conservation planning is important to ensure the maintenance of patterns and processes needed to support the persistence of biodiversity. In freshwater ecosystems, spatial connectivity is constrained by the presence of water, which exhibits marked temporal changes in regions with wet–dry seasonal climates. Previous studies have focused on spatial connectivity and overlooked the temporal component, which is required for the functionality of spatial connections (because of temporal changes in water availability).We identify priority areas for the conservation of freshwater fish, waterbirds and turtles in theMitchellRiver catchment in the wet–dry tropics of northernAustralia. We demonstrate how adequacy of freshwater conservation can be enhanced by integrating an estimate of water residency time (WRT) into the prioritization process.WRTreflects refugial potential and connectivity in freshwater ecosystems and was quantified usingModerateResolutionImagingSpectroradiometer (MODIS) flood and post‐floodLandsat satellite imagery. We compare the spatial allocation of priority areas and the spatial and temporal connectivity under two alternative scenarios: (i) accounting only for spatial connectivity and (ii) integrating spatial and temporal connectivity.Priority areas identified under the spatial and temporal connectivity scenario showed a 40% increase inWRTvalues with respect to the traditional spatial connectivity scenario. This was achieved at no additional cost in terms of total protected area and maintaining the same spatial connectivity.Despite priority areas identified under the two alternative scenarios showing intermediate spatial overlap (64%), the selection process was more efficiently biased towards planning units with highWRTvalues.WRTin planning units that were only selected under the temporal connectivity scenario was 2·5 times higher than in planning units that only appeared in the traditional connectivity scenario. This reveals the importance of accounting forWRTwhen identifying freshwater priority areas in wet–dry seasonal environments.Synthesis and applications: Considering the temporal connectivity in conservation prioritization as we propose here helps to assess periods of longest spatial connections, thereby maximizing the refugial role of freshwater priority areas during dry periods. Using publicly available satellite imagery data and software, our approach allows improved management of aquatic resources and biodiversity during periods of water scarcity, which may increase in incidence and duration with climate change.

Pharmaceuticals on a sewage impacted section of a Mediterranean River (Llobregat River, NE Spain) and their relationship with hydrological conditions

Mediterranean rivers are characterized by a high flow variability, which is strongly influenced by the seasonal rainfall. When water scarcity periods occur, water flow, and dilution capacity of the river is reduced, increasing the potential environmental risk of pollutants. On the other hand, floods contribute to remobilization of pollutants from sediments. Contamination levels in Mediterranean rivers are frequently higher than in other European river basins, including pollution by pharmaceutical residues. Little attention has been paid to the transport behavior of emerging contaminants in surface waters once they are discharged from WWTP into a river. In this context, this work aimed to relate presence and fate of emerging contaminants with hydrological conditions of a typical Mediterranean River (Llobregat, NE Spain). River fresh water samples were collected twice a week over a period of 5 weeks at three sampling points. Sixty-six pharmaceutical compounds belonging to different therapeutical classes were analyzed by LC-MS/MS. Positive and negative correlations between the concentrations of the target analytes and hydrological variables like river flow and dissolved organic matter were observed pointing out the relevance of different hydrological phenomena like dilution effects or sediment re-suspension. Sensitivity calculations showed that the majority of compounds were sensitive to flow variations.

Dry spell analysis for effective water management planning

Knowing the dry and wet periods with rainy seasons is essential for successful water management planning in any particular area. With this view, this study analyzed the thirty years (1975-2004) monthly rainfall data of Udumalpet station located in Parambikulam Aliyar sub basin (Tamilnadu) on annual, seasonal and monthly basis for planning a suitable water conservation management system. Sixty two per cent of the total rainfall is received from North East Monsoon and seventeen per cent from South-West Monsoon. In the study period, four years were found to be wet, four years were found to be dry and the remaining twenty two years were found to be normal years. The analysis showed that the annual and seasonal rainfall data did not clearly indicate the problem of drought in the region; whereas the monthly rainfall data indicated serious concerns to deal with drought particularly during the winter and summer months. It also revealed that the winter months were the most susceptible to severe drought conditions. Out of 30 years of study, January and February were found to be the dry months which normally facilitate for the good harvest of the kharif sown long duration crops. There is a need to adopt adequate moisture conservation measures like mulching etc. to mitigate the effect of drought spells during critical periods of crop growth, and to construct water harvesting ponds/tanks for application of pre-sowing irrigation to Rabi (winter) crops, and supplemental irrigation during periods of water scarcity.

Carbon and nitrogen stoichiometry in Brassica napus L. seedlings after supplementation with Ca2+ and K+ under irrigated and drought stress conditions

Exposure of plants to long periods of water scarcity, mainly in arid and semi-arid regions, is one of the major reasons for over 50% reduction in average yields. Proper management of Brassica napus to enhance its ability to survive under drought and high temperature stress at early growth stages, besides development of tolerant genotypes, could improve its production in the rainfed areas. In the present study, we report the interactive effects of Ca 2+ , K + and N supplementation and water availability on the fresh biomass, N and C content, as well as C/N ratio of crop plants. Exposure to water stress significantly reduced the fresh biomass, Nitrogen (N), Carbon (C) content and the C/N ratio. Ca 2+ and K + supplementation before drought positively affected fresh biomass by stimulating N uptake and C assimilation. However, the C/N ratio was reduced after supplementation with Ca 2+ and K + . The N supplementation before drought imposition, though enhanced the N uptake, but the excessive damage to cell membranes and electrons leakage from Electron Transport Chain (ETC) during photosynthesis resulted in a decrease in C assimilation. Consequently, there was a decrease in the C/N ratio in seedlings exposed to drought after supplementation with N. Key words : Drought, nutrients supplementation, carbon, nitrogen, C/N ratio.

Population dynamics and tolerance to desiccation in a crustacean ostracod adapted to life in small ephemeral water bodies

Given their small size, isolation and unpredictability, temporary rockpools present high environmental stress and impoverished communities of species that have adapted to such stressful conditions. Special adaptations of the invertebrates living in these habitats include tolerance to desiccation and fast ontogenetic development in order to maintain stable populations and face high risk of extinction. Dozens of small rockpools (mostly with Ø < 1 m) can be found in east Spain on limestone substrate, where the only known Iberian populations of Heterocypris bosniaca Petkovski et al. (2000) , an ostracod species with geographic parthenogenesis, have been recently found. In this survey, two of these rockpools have been monitored during the main hydroperiod between the fall of 2005 and summer 2006 to test the ability of H. bosniaca parthenogenetic populations to face unpredictable hydroperiod dynamics. Pools were visited weekly, and limnological data and ostracod samples were obtained from either water or substrate in dry periods. Ostracod individuals were counted and assigned to growth instars to monitor population changes. In the laboratory, experimental cultures allowed the estimation of survival dependence on the substrate desiccation rate. Throughout the hydrological cycle studied, several hatching periods were observed, usually preceded by desiccation, followed by substrate hydration and water dilution by rain. The demographic changes observed indicate that H. bosniaca populations are able to persist in intermittently inundated environments and produce several generations per annual hydrological cycle. In addition, adult individuals were able to survive in the wet mud of dry pools for longer than five weeks. The experimental data suggest a lower average survival time when exposed to desiccation processes, and that the velocity of substrate water loss is a determining factor for the survival rate of ostracods resisting dry events in temporary ponds. As shown by ostracods’ life histories in temporary aquatic environments undergoing unpredictable desiccation events, a combined strategy of adult tolerance to short periods of water scarcity and rapid hatching from resting egg banks can be advantageous for the monopolization of small-sized ephemeral habitats.

Mazama gouazoubira (Cervidae) diet during the dry season in the arid Chaco of Córdoba (Argentina)

Grey brocket deer diet selection was studied during a period of water scarcity in the arid Chaco of Córdoba province, Argentina. Sampling took place during the dry season in and around Chancaní Provincial Reserve (Pocho department). Forty-eight fresh fecal samples were collected from 85 sampling plots located at random. Plant cover and abundance were used to estimate food availability. Diet composition was determined using microscopic analysis of brocket feces and resource selection was calculated using Ivlev’s Selectivity Index. Thirty-three plant species were identified in the diet. Fruits were found in high proportion (12.4%). Woody plants made up 67.7% of the diet; the most consumed species were Castela coccinea (23.1%), Maytenus spinosa (10.2%), Condalia microphylla (9.5%), Schinus fasciculatus (8.5%) and Ximena americana (7.4%). Mazama gouazoubira selects woody and succulent plants, while herbs are consumed according to availability and grasses in a proportion that is below what is available.

Review Essay: Water and Culture in Australia: Some Alternative Perspectives

Australia is currently experiencing a prolonged period of water scarcity that is challenging a diverse range of water-dependent activities ranging from household gardening to horticultural production to the viability of riverine ecosystems. The political and ecological importance of water in Australia is not, however, only a recent phenomenon. For the majority of Australia’s settled history, water politics, economics, culture and engineering have reflected and embodied a dynamic relationship between Australian hydrology and Australian society. This essay examines that relationship by first reviewing the work of the Australian historical geographer, Emeritus Professor J. M. Powell. For 40 years Powell has been writing about the process of natural resource appraisal and management in Australia and he has been Australia’s leading authority on the role of water in that process for most of that time. The essay then argues for an extension of Powell’s work by applying the insights provided by the scholars Karl Wittfogel, Donald Worster and Eric Swyngedouw. Their work, it is argued, suggests the possibility of a more nuanced understanding of water in Australia than that currently offered by the majority of the Australian literature, and ultimately provides some tools for thinking ourselves out of the current water crisis.

Scenario-based assessment and management of water resources in mid-Himalayan micro-watersheds with limited data availability

A conceptual hydrological water balance model has been developed and employed to assess the water availability in a mid-Himalayan watershed and analyse the dynamics of water supply and its utilization under different scenarios arising out of present and future developments. The model was calibrated and validated using daily runoff and rainfall data at different locations in the watershed. The water availability in streams and springs to meet the human, animal and crop requirements was assessed, and was found to vary in different quarters of the year with inequalities existing in different parts of the watershed. The model was successfully applied to analyse the impact of land-use changes and weather aberrations on water availability in the present and future scenarios. The drought scenarios are more critical in causing water scarcity in a given location, compared to the impact of land-use changes. The findings can be applied for assessing, planning and allocation of water resources among different sectors of water use in hilly areas and to make informed decisions during critical periods of water scarcity.

Primary and complex stressors in polluted mediterranean rivers: Pesticide effects on biological communities

Summary We examined the presence of pesticides in the Llobregat river basin (Barcelona, Spain) and their effects on benthic biological communities (invertebrates and diatoms). The Llobregat river is one of Barcelona’s major drinking water resources. It has been highly polluted by industrial, agricultural, and urban wastewaters, and—as a typical Mediterranean river—is regularly subjected to periodic floods and droughts. Water scarcity periods result in reduced water flow and dilution capacity, increasing the potential environmental risk of pollutants. Seven sites were selected, where we analysed the occurrence of 22 pesticides (belonging to the classes of triazines, organophosphates, phenylureas, anilides, chloroacetanilides, acidic herbicides and thiocarbamates) in the water and sediment, and the benthic community structure. Biofilm samples were taken to measure several metrics related to both the algal and bacterial components of fluvial biofilms. Multivariate analyses revealed a potential relationship between triazine-type herbicides and the distribution of the diatom community, although no evidence of disruption in the invertebrate community distribution was found. Biofilm metrics were used as response variables rather than abundances of individual species to identify possible cause-effect relationships between pesticide pollution and biotic responses. Certain effects of organophosphates and phenylureas in both structural and functional aspects of the biofilm community were suggested, but the sensitivity of each metric to particular stressors must be assessed before we can confidently assign causality. Complemented with laboratory experiments, which are needed to confirm causality, this approach could be successfully incorporated into environmental risk assessments to better summarise biotic integrity and improve the ecological management.

Xylem potential- and water content-breakpoints in two wetland forbs: indicators of drought resistance in emergent hydrophytes

Freshwater wetlands commonly occur along the boundaries between terrestrial upland and deep open-water systems, and are consequently prone to dynamic and often highly variable hydrological regimes. Physiological adaptations to drought would be advantageous in emergent vegetation, as wetlands are often susceptible to short periods of water scarcity through seasonal declines in precipitation and/or surface water runoff. This study used 15 l microcosms to examine xylem water potential (ψxylem)- and tissue water content (θ)-breakpoints in 2 wetland forbs (Justicia americana and Saururus cernuus) to determine how these plants respond to short-term (2 wk) water deficits. Overall, treatment responses by these forbs included reductions in both θ and ψxylem during the second week of drought, followed by rapid recoveries of θ and ψxylem within a few days of water repletion. Rapid tissue-water recovery, following extreme water deficits (soil moisture levels <3%), is beneficial to plants residing in areas prone to intense water fluctuations. Furthermore, while θ and ψxylem breakpoints in S. cernuus occurred as soil moisture levels fell below 12% (ca. -800 kPa soil water potential), breakpoints for J. americana occurred at considerably lower soil moisture levels (ca. 7 and 10% soil water content for θ and ψxylem, respectively; or less than -1500 kPa soil water potential). The lower breakpoints observed in J. americana were comparable to values reported for terrestrial grasses, including species adapted to dryer, xeric conditions. Therefore, the results from this study suggest that some wetland forbs are physiologically adapted to environments that undergo rapid changes in water hydrology, including the ability to tolerate short-term water scarcity com- parable to dryer upland systems.

Post-Wildfire Recovery of Riparian Vegetation during a Period of Water Scarcity in the Southwestern USA

Wildland fires occur with increasing frequency in southwestern riparian forests, yet little is known about the effects of fire on populations of native and exotic vegetation. From 2003 to 2006, we monitored recovering woody vegetation in wildfire sites in the bosque (riparian forest) along the Middle Rio Grande of central New Mexico, USA. To examine recovery potential, we estimated densities of native Rio Grande cottonwood (Populus deltoides ssp. wislizenii) and exotic saltcedar (Tamarix ramosissima) in burned plots and estimated mortality rates of resprouts. Exotic vegetation density was higher in most burned sampling plots than in paired unburned plots. Native shrub density was lower in most burned sampling plots than in unburned plots, although the effect sizes were small. Native tree density did not differ between burned and unburned plots, despite relatively high mortality of cottonwood resprouts. All observed cottonwood mortality occurred between 2003 and 2004, following the hottest and driest summer of the study. Cottonwood resprouts had the lowest apparent mortality rate at the site with the lowest depth to ground-water. Saltcedar resprout mortality was low at all wildfire sites, consistent with previous studies showing that this species is less sensitive to drought and better adapted to wildfire than cottonwood and other native species. Our observations suggest that, in the absence of ideal hydrologic and climatic conditions, fire can reduce cottonwood density in the bosque and promote the spread of saltcedar. Increasingly xeric conditions predicted under most climate change scenarios could result in greater recovery of exotic saltcedar over native vegetation.

Water Scarcity and the Sustainability of a Common Pool Resource Institution in the Urban Andes

The Cochabamba Water War of 2000 was precipitated by Bolivians’ defense of common-pool water resources and institutions against privatization. This article examines the design of a water institution and its sustainability during periods of water scarcity in urban Cochabamba. Based on data collected via participant-observation and panel surveys conducted in 72 randomly selected households, I draw three main conclusions. First, the institution operated according to principles found in sustainable resource management institutions in the rural Andes (Trawick 2001) and across cultures (Ostrom 1990). Second, while the function of the common-pool resource institution was stable over the five study periods, the social structures that supported collective choice and operational rules were sensitive to external events including seasonal water scarcity. Third, while institutions with strong historical precedents for contingencies under resource stress may be sustainable, other forms of social organization on which the institution depends may be more vulnerable to water scarcity.

Dam effects on droughts magnitude and duration in a transboundary basin: The Lower River Tagus, Spain and Portugal

This study examines the effects of a large dam on hydrological droughts in the transboundary Tagus River, central Spain and Portugal. The magnitude and duration of droughts are analyzed by comparing a monthly drought index calculated for the flow series upstream and downstream of the Alcántara reservoir. The dam was built in 1969, and the reservoir is the second largest in Europe (3,162 hm3). Water management in the area is complex because of large seasonal and interannual variability in the flow regime, which is characteristic of Mediterranean environments. This paper demonstrates that, as a result of exploitation of the Alcántara reservoir, (1) during periods of water scarcity, the releases in winter and spring are reduced dramatically and the magnitude and duration of summer low flow show a slight increase and (2) the nature of droughts along the Tagus river basin downstream of the dam has shown severe changes since construction of the dam. In fact, during the predam period (1943–1969), droughts were longer and more intense in the Spanish part of the basin than that in the Portuguese part. Since the construction of the Alcántara dam, however, the Portuguese part of the basin has experienced more severe droughts than did the upstream part in terms of both magnitude and duration.