Daily Water Use Research Articles

Consequences of nocturnal water loss: a synthesis of regulating factors and implications for capacitance, embolism and use in models.

Total daily water use is a key factor influencing the growth of many terrestrial plants, and reflects both day-time and nocturnal water fluxes. However, while nocturnal sap flow (En) and stomatal conductance (gs,n) have been reported across a range of species, ecosystems and microclimatic conditions, the regulation of these fluxes remains poorly understood. Here, we present a framework describing the role of abiotic and biotic factors in regulating En and gs,n highlighting recent developments in this field. Across ecosystems, En and gs,n generally increased with increasing soil water content and vapor pressure deficit, but the interactive effects of these factors and the potential roles of wind speed and other abiotic factors remain unclear. On average, gs,n and En are higher in broad-leaved compared with needle-leaved plants, in C3 compared with C4 plants, and in tropical compared with temperate species. We discuss the impacts of leaf age, elevated [CO2] and refilling of capacitance on night-time water loss, and how nocturnal gs,n may be included in vegetation models. Younger leaves may have higher gs,n than older leaves. Embolism refilling and recharge of capacitance may affect sap flow such that total plant water loss at night may be less than estimated solely from En measurements. Our estimates of gs,n for typical plant functional types, based on the published literature, suggest that nocturnal water loss may be a significant fraction (10-25%) of total daily water loss. Counter-intuitively, elevated [CO2] may increase nocturnal water loss. Assumptions in process-based ecophysiological models and dynamic global vegetation models that gs is zero when solar radiation is zero are likely to be incorrect. Consequently, failure to adequately consider nocturnal water loss may lead to substantial under-estimation of total plant water use and inaccurate estimation of ecosystem level water balance.

Comparing substrate moisture-based daily water use and on-demand irrigation regimes for oakleaf hydrangea grown in two container sizes

Independently controlled irrigation plots were designed to test two container nursery irrigation regimes on oakleaf hydrangea (Hydrangea quercifolia ‘Alice’) in both nursery and controlled greenhouse environments. The experiments were conducted in both 3.8 and 11.4L containers. Plants were automatically irrigated by one of two soil moisture sensor-based regimes: (1) a daily water use (DWU) system that delivered the exact amount of water that had been lost in the previous 24h and (2) an on-demand (OD) irrigation system based on a specific substrate moisture content derived from the relationship between substrate moisture and photosynthetic rate. In this system, irrigation was applied when the substrate moisture level fell below 33% container capacity, which corresponded to 90% maximum predicted photosynthetic rate. Both treatments delivered the volume of water required to return the containers to container capacity by overhead irrigation, but the DWU system was static, irrigating once per day, whereas OD was dynamic and irrigated whenever the substrate moisture reached the 33% threshold level. Gas exchange was measured at the driest point prior to the next irrigation event. Periodical growth index, water use, and final dry weight were recorded. OD used less water than DWU outdoors, reduced leaching fraction among greenhouse experiments, and had either no or a positive impact on biomass in all but one trial. For 3.8L plants, photosynthesis and stomatal conductance were consistently greater when irrigated by the OD program. Both treatments used significantly less water than the industry standard of 2.5cm per day. This research demonstrated that both DWU and OD are a dramatic improvement over conventional irrigation scheduling and could be adopted as conservative irrigation systems for nursery production.

The isohydric cv. Montepulciano (Vitis vinifera L.) does not improve its whole-plant water use efficiency when subjected to pre-veraison water stress

Understanding how water use efficiency (WUE) changes under drought is crucial for interpreting adaptive responses of species and cultivars to such abiotic stress. Several recent papers have concluded that in grapevine these responses and the guidelines stemming therefrom can differ, depending upon the parameter chosen to express WUE. In the present paper a complete set of WUE expressions, including the physiological and agronomical, were compared in potted, fruiting cv. Montepulciano (Vitis vinifera L.) grapevines which were either well watered (WW) or subjected to progressive pre-veraison drought (WS) by supplying decreasing fractions (i.e. 70%, 50% and 30% of daily vine transpiration, Tg) determined gravimetrically before vines were fully rewatered. While single-leaf intrinsic water-use efficiency (WUEi) increased with water stress severity, seasonal and diurnal whole-canopy WUE were similar at pre-stress, 70% Tg, and upon rewatering but dropped in WS during severe water stress. Agronomic WUE calculated as mass of dry weight stored in annual biomass (leaves, canes and bunches) per L of water used, was also lower in WS, whereas WS had similar must composition with WW despite a 37% reduction in the yield per vine. Results warn that whole-canopy WUE is a much better index than any single-leaf based WUE parameter for extrapolation to agronomic WUE and actual grape composition. Under our specific case study, it can be recommended that, to avoid significant profit loss, water supply to drought stressed Montepulciano at pre-veraison should not be lower than 70% of daily vine water use.

Water use efficiency in Sangiovese grapes (Vitis vinifera L.) subjected to water stress before veraison: different levels of assessment lead to different conclusions.

Several recent papers have shown that in grapevine (Vitis vinifera L.), interpretation of responses to drought can differ depending upon the parameter chosen to express water use efficiency (WUE). In the present paper, a series of WUE expressions, including physiological and agronomical, were compared in potted grapevines (Vitis vinifera L. cv. Sangiovese) that were either well-watered (WW) or subjected to progressive drought before veraison (WS) by supplying decreasing fractions (i.e. 70%, 50% and 30% of daily vine transpiration (Trd) determined gravimetrically before vines were fully rewatered. Although single-leaf intrinsic and instantaneous WUE increased with water stress severity, seasonal and whole-canopy WUE were similar to that before stress, at 70% Trd and upon rewatering, but dropped during severe water stress. WUE calculated as mass of DW stored in annual biomass (leaves, canes and bunches) per litre of water used did not differ on a seasonal basis, whereas WS plants showed lower must soluble solids at harvest, and unchanged colour and phenolic concentration in spite of smaller berries with higher relative skin growth. Results confirm that whole-canopy WUE is a much better index than any single-leaf based WUE parameter for extrapolation to agronomic WUE and actual grape composition. In our specific case study, it can be recommended that water supply to drought-stressed Sangiovese grapevines before veraison should not be lower than 70% of daily vine water use.

Effects of Different Irrigation Amounts on Water Use of Precocious Walnuts

Objective : To provide scientific guidance for water management of precocious walnuts. Method: With 8 years old ‘Lvling’ walnut trees as samples, 5 irrigation quantity treatments were designed, including 0, 15, 30, 45 and 60 kg of water per plant for each time, respectively and the routine irrigation amount (CK) was 600 kg of water per plant for each time. During the draught stage in growing season, 3 times of irrigation were carried out, and the effects of different treatments on sap flow, water use efficiency, yield and fruit quality were compared. Results: The daily instantaneous maximum average sap flow rates were found with 60 kg of water and control; the daily highest average water use efficiency was 1.54 mmol/mol with the treatment of 30 kg water; the daily highest average leaf water potential was-1.23 MPa with control; the highest yield per plant (1.48 kg) was found with the control, and the yield of 45 kg and 60 kg water per plant one time accounted for 98.65% and 99.32% of that of control, respectively. with T1 the yield was the lowest, only accounting for 70.65% of the control. Conclusion: As the soil water contents increased, the diurnal variation curve of sap flow rates changed from unimodal to bimodal patterns in sunny days, the main peak was narrowed; the curve of diurnal variation of leaf water potential changed from "V" to "W" type; the leaf water use efficiency increased initially and then decreased later; and the nut quality was improved and the yield increased. The optimal soil water content (SWC) of 'Lvling' precocious walnuts ranged from 20.01% ~ 21.96%.

Urban water consumption and weather variation in the Portland, Oregon metropolitan area

This paper analyzed the evolving response of daily water use to weather fluctuations over 29years (1981–2009) for two Portland-area municipal water providers – Portland Water Bureau (PWB), serving a dense urban area, and Tualatin Valley Water District (TVWD), serving a rapidly growing suburban area. Temperature sensitivity, the response of water use to a temperature increase, generally declined for both water providers. A downward shift in temperature sensitivity was identified for PWB in 1992, owing to outdoor water use curtailment during a water scarcity event, followed by aggressive demand management measures. No corresponding shift was detected for TVWD due to high suburban growth rates throughout the 1990s. Recent downward step changes in temperature sensitivity for both providers indicated some modicum of convergence in water use patterns, reflecting converging trends in socio-economic and land development characteristics in both areas. We argue that a confluence of historical factors, including the 1992 drought, aggressive (though uneven) demand management, changes to the building code, and ongoing densification of both urban and suburban areas, have reduced per-capita water use and attenuated the connection between water use and temperature. Softening the seasonality of water use represents an important but often-overlooked component of urban climate change adaptation.

Performance of simple irrigation scheduling calendars based on average weather data for annual ryegrass

Poor irrigation management in pastures can lead to yield and quality reduction as well as loss of income through extra pumping and leaching of nitrate fertiliser. A number of irrigation scheduling techniques of varying levels of sophistication have been developed over the years to address limited irrigation water availability and maximise productivity. Despite this, the adoption of irrigation scheduling tools by farmers remains low. The objective of this study was to assess the use of simple irrigation scheduling calendars based on average weather data to improve irrigation management in ryegrass. The calibrated Soil Water Balance (SWB) model was used to generate simple irrigation calendars and assess effectiveness for different scenarios by mechanistically simulating water dynamics and pasture growth. Scheduling irrigation using the calendars gave similar irrigation applications, water losses and yields compared to a more scientific real-time scheduling (in response to soil water depletion by the crop). While site-specific irrigation scheduling calendars can easily be generated by consultants and irrigators, even simpler monthly estimates of average daily water use can also be useful. Application of calendars by farmers is encouraged to improve water and nutrient use efficiency of irrigated pastures, if real-time irrigation scheduling is not employed.

A critical review of methods used to obtain flow patterns and volumes of individual domestic water using appliances

Determining the daily flow rates and water use patterns of specific household fixtures and appliances is important for water use monitoring, deriving effective strategies for water demand management, designing onsite water reuse systems, and efficient planning and investment in the urban water sector. Currently, there are a limited number of publications which address the need to measure flow patterns and volumes of individual household water-using appliances, or which analyze the alternatives to do so. This paper critically reviews and compares different methods of obtaining the specific flow patterns and volumes of water used by individual household water-using microcomponents (i.e. toilet, bath/shower, washbasin, washing machine, kitchen sink, dishwasher, etc.) in order to make recommendations about the appropriateness of these methodologies for various applications.

Hydrology-oriented (adaptive) silviculture in a semiarid pine plantation: How much can be modified the water cycle through forest management?

Hydrology-oriented silviculture might adapt Mediterranean forests to climatic changes, although its implementation demands a better understanding and quantification on the water fluxes. The influence of thinning intensity (high, medium, low and a control) and its effect on the mid-term (thinned plots in 1998 and 2008) on the water cycle (transpiration, soil water and interception) and growth [basal area increment (BAI)] were investigated in 55-year-old Aleppo pine trees. Thinning enhanced a lower dependence of growth on climate fluctuations. The high-intensity treatment showed significant increases in the mean annual BAI (from 4.1 to 17.3 cm2) that was maintained in the mid-term. Thinning intensity progressively increased the sap flow velocity (v s) in all cases with respect to the control. In the mid-term, an increased functionality of the inner sapwood was also observed. Mean daily tree water use ranged from 5 (control) to 18 (high intensity) l tree−1. However, when expressed on an area basis, daily transpiration ranged from 0.18 (medium) to 0.30 mm (control), meaning that in spite of the higher transpiration rates in the remaining trees, stand transpiration was reduced with thinning. Deep infiltration of water was also enhanced with thinning (about 30 % of rainfall) and did not compete with transpiration, as both presented opposite seasonal patterns. The changes in the stand water relationships after 10 years were well explained by the forest cover metric. The blue to green water ratio changed from 0.15 in the control to 0.72 in the high-intensity treatment, with the remaining treatments in the 0.34–0.48 range.

WATER, FOOD AND ENERGY SUPPLY CHAINS FOR A GREEN ECONOMY

ABSTRACTA new paradigm for sustainable, integrated, water resources management is emerging from international conferences around the world. Its most succinct description is ‘the water–food–energy nexus for a green economy’. The water, food and energy nexus aims at the most efficient, best practice principles applied throughout the full food supply chain. This includes consideration of reducing wastage of the food for various reasons in the supply chain. This paper describes the global opportunities for better efficiency and resources conservation in the water, food, and energy supply chains with examples from Australia. Food wastage equates on average to 243 l day−1 of water per person in the food they throw away, which is 1.5 times the daily water use per person in the UK. The concepts of virtual water and water footprint can help in identifying opportunities to save water by targeting reduction of wastage of food that has the highest virtual water content. A green economy aims at achieving optimised supply chain objectives in a manner that espouses the sustainability principle, gives due attention to environmental concerns and helps with eradication of poverty and hunger. Copyright © 2014 John Wiley & Sons, Ltd.

Impact of rapid urbanisation and industrialisation on river sediment metal contamination

This study aimed at evidencing contaminant inputs from a rapidly growing population and the accompanying anthropogenic activities to river sediments. The Fez metropolitan area and its impacts on the Sebou's sediments (the main Moroccan river) were chosen as a case study. The Fez agglomeration is surrounded by the river Fez, receiving the wastewaters of this developing city and then flowing into the Sebou. The sediment cores from the Fez and Sebou Rivers were extracted and analysed for major elements, butyltins and toxic metals. Normalised enrichment factors and geoaccumulation index were calculated. Toxicity risk was assessed by two sets of sediment quality guideline (SQG) indices. A moderate level of contamination by butyltins was observed, with monobutyltin being the dominant species across all sites and depths. The lowest level of metal pollution was identified in the Sebou's sediments in upstream of Fez city, whilst the Fez' sediments were heavily polluted and exhibited bottom-up accumulation trends, which is a clear signature of recent inputs from the untreated wastewaters of Fez city. Consequently, the sediments of Fez and Sebou at the downstream of the confluence were found to be potentially toxic, according to the SQG levels. This finding is concerned with aquatic organisms, as well as to the riverside population, which is certainly exposed to these pollutants through the daily use of water. This study suggests that although Morocco has adopted environmental regulations aiming at restricting pollutant discharges into the natural ecosystems, such regulations are neither well respected by the main polluters nor efficiently enforced by the authorities.

Soil-water dynamics in a pasture-cropping system

Pasture cropping is a farming system in which annual crops are sown into established perennial pastures. It may provide environmental benefits such as increased groundcover and reduced deep drainage, while allowing traditional crop production in the Mediterranean-style climate of south-western Australia. In this research, we investigated deep drainage and the temporal patterns of water use by a subtropical perennial grass, annual crops, and a pasture-cropping system over a 4-year period. Both the pasture and pasture-cropped treatments reduced deep drainage significantly, by ~50 mm compared with the crop treatment. Competition between the pasture and crop components altered patterns of average daily water use, the pasture-cropped treatment having the highest water use for July, August and September. Consequently, water-use efficiency for grain production was lower in the pasture-cropped plots. This was offset by pasture production, so that over a full 12-month period, water-use efficiency for biomass production was generally greater for the pasture-cropped plots than for either the pasture or crop monocultures. Pasture cropping may be a viable way of generating sustainable economic returns from both crop and pasture production on sandy soils of south-western Australia.

Can the Technocrats Calm Peru’s Troubled Waters?

The law should bring modernity to water use in our country, modernity in the daily and domestic use of water; we must all prepare ourselves to face a difficult future with regard to water.

Spectral Crop Coefficient Approach for Estimating Daily Crop Water Use

While the amount of water used by a crop can be measured using lysimeters or eddy covariance systems, it is more common to estimate this quantity based on weather data and crop-related factors. Among these approaches, the standard crop coefficient method has gained widespread use. A limitation of the standard crop coefficient approach is that it applies to “standard conditions” that are invariant from field to field. In this article, we describe a method for estimating daily crop water use (CWU) that is specific to individual fields. This method, the “spectral crop coefficient” approach, utilizes a crop coefficient numerically equivalent to the crop ground cover observed in a field using remote sensing. This “spectral crop coefficient” Ksp is multiplied by potential evapotranspiration determined from standard weather observations to estimate CWU. We present results from a study involving three farmers' fields in the Texas High Plains in which CWU estimated using the Ksp approach is compared to observed values obtained from eddy covariance measurements. Statistical analysis of the results suggests that the Ksp approach can produce reasonably accurate estimates of daily CWU under a variety of irrigation strategies from fully irrigated to dryland. These results suggest that the Ksp approach could be effectively used in applications such as operational irrigation scheduling, where its field-specific nature could minimize over-irrigation and support water conservation.

Simulation and Evaluation on Daily Consumptive Water Use in Fields Affected by Meteorological Conditions and Soil Water Content

Simulation and Evaluation on Daily Consumptive Water Use in Fields Affected by Meteorological Conditions and Soil Water Content

Shade Intensity Influences Water Use and Growth of Three Viburnum Species

Water use, growth, and leaf necrosis of Burkwood viburnum, Korean spice viburnum, and leatherleaf viburnum were evaluated on plants grown in 0 (full sun), 30, or 60% shade during 2010 and 2011. In both years, total water use of Burkwood viburnum decreased with increased shade intensity. Water use of leatherleaf viburnum was lowest in 0% and highest in 30% shade. Daily water use was lower in 0% than in 30 or 60% shade for leatherleaf viburnum plants in August of both years and September of 2010 due to greater leaf necrosis, leaf abscission, and less growth in height and width. In both years, growth in height and width, and leaf number at harvest generally increased in all three species with increased shade intensity. All species had a larger leaf area, stem dry weight, and root dry weight in 30 and 60% than in 0% shade. Shade intensity did not influence root to shoot (R/S) ratio in Burkwood viburnum in 2010, but in 2011, a curvilinear relationship occurred between R/S ratio and shade intensity. Root to shoot ratio of Korean spice and leatherleaf viburnum decreased linearly in 2010 but curvilinearly in 2011 with increasing shade. Leaf necrosis ratings were lower in shaded plants of all three species in both years. Results indicate that greater plant growth, quality, and water use efficiency occurs when these three viburnum species are grown in shade than when they are grown in full sun.

Cacao trees under different shade tree shelter: effects on water use

We asked how shade tree admixture affects cacao water use in agroforests. In Central Sulawesi, Indonesia, cacao and shade tree sap flux was monitored in a monoculture, in a stand with admixed Gliricidia trees and in a mixture with a multi-species tree assemblage, with both mixtures having similar canopy openness. A Jarvis type sap flux model suggested a distinct difference in sap flux response to changes in vapor pressure deficit and radiation among cacao trees in the individual cultivation systems. We argue that differences originate from stomatal control of transpiration in the monoculture and altered radiation conditions and a different degree of uncoupling of the VPD from the bulk atmosphere inside shaded stands. Probably due to high sap flux variability among trees, these differences however did not result in significantly altered average daily cacao water use rates which were 16 L day−1 in the multi-species assemblage and 22 L day−1 in the other plots. In shaded stands, water use of single cacao trees increased with decreasing canopy gap fraction in the overstory since shading enhanced vegetative growth of cacao fostering transpiration per unit ground area. Estimated transpiration rates of the cacao tree layer were further controlled by stem density and amounted to 1.2 mm day−1 in the monoculture, 2.2 mm day−1 for cacao in the cacao/Gliricidia stand, and 1.1 mm day−1 in the cacao/multi-species stand. The additional transpiration by the shade trees is estimated at 0.5 mm day−1 for the Gliricidia and 1 mm day−1 for the mixed-species cultivation system.

Performance Measurement Via Sap Flow Monitoring of Three Eucalyptus Species for Mine Site and Dryland Salinity Phytoremediation

Monitoring of trees with reliable technology is essential in phytoremediation. Sap flow instrumentation on three Eucalyptus species at a mine site in western Victoria, Australia, was used to determine which species is best suited to meet the goals of a phytoremediation project. Specifically, the aim of the monitoring was to determine which species could better tolerate the hypersaline soil, potentially lower saline ground water, and cope with expected hotter and drier weather given climate change scenarios. Over a summer period, average daily water use of E. cladocalyx was approximately six times greater than E. melliodora and four times greater than E. polybractea. During a three day heat wave event, E. cladocalyx was found to have a higher tolerance to extreme temperature. The optimal VPD / temperature for tree transpiration was 2.6 kPa / 26.2 °C for E. cladocalyx, 2.1 kPa / 23.9 °C for E. melliodora, and 2.0 kPa / 23.2 °C for E. polybractea. Through sap flow monitoring, it was determined that E. cladocalyx could better tolerate saline soils, hotter and drier weather, and had greater potential to lower saline ground water.

Sap flow and water use in African baobab (Adansonia digitata L.) seedlings in response to drought stress

The African baobab (Adansonia digitata L.) is an important multi-purpose fruit tree with high potential for domestication in drier Africa. Although adult individuals are well-known to be drought resistant, only little has been reported on how young baobab trees can survive drought. Therefore, the aim of this study was to examine short-term soil drought effects on water relations of baobab seedlings. Baobab seedlings used a limited amount of stored water to buffer daily water deficits (~8.5gd−1), which contributed up to only ~17.5% of daily water use and ~6% of total plant water. Under drought, a strong reduction in stomatal conductance (~85%) resulted in a midday leaf water potential of −1MPa and zero stem sap flow followed by significant leaf loss. Plant anatomy evidenced the presence of water storage tissues and the vulnerability to xylem embolism. The taproot was the most important plant part for water storage (68% of total plant water), suggesting root-succulence rather than stem-succulence. When drought intensified, limitation of leaf transpiration and/or root water uptake led to drought-enforced dormancy. Despite the large amounts of water stored in the taproot (~90%) and the stem (~75%), only a limited amount of stored water appeared to be used to sustain upper leaves and plant metabolism during the dormant period, and to facilitate recovery following water supply. Drought avoidance, conservative water use and the presence of internal stored water allow baobab seedlings to survive drought.

TRANSPIRATION OF TREE SPECIES IN DIFFERENT VERTICAL LAYERS OF A KANDYAN FOREST GARDEN

Water use of a forest ecosystem is: nn important determinant of the water balance of a wholewatershed. Kandyan Forest Gardens (KFGs) contain a mixture of different tree species. Thedifferent tree species are of different sizes and are arranged into distinct vertical canopy layers.The total water use of the KFG is determined by the transpiration rates of individual trees, whichform these different vertical layers.The study was conducted in a KGF at Pilapitiya, Pilimathalawa in the Mid-Country Wet Zone(WM3) during the period from Marci to July 2001. A vegetation survey showed that there were56 tree species in this KFG. Out cf these, three tree species representing three vertical canopylayers were selected for continuous measurement of transpiration. These were Jak (ArtocarpusheterophyIlus), toona (Toona ciliata) and Mahogany (Swietenia macrophylla) which representedupper, middle and lower canopy layers respectively. Transpiration of all trees was measured asthe sap flow in their trunks using two thermal methods. In jak (DBH = 40.5 ern) and toona(DBH=9cm), which had larger trunks, sap flow was measured using thermal dissipation probes.In mahogany, which had a smaller trunk (DBH=3cm), sap flow was measure using a dynagage.Solar radiation incident on the respe-ctive tree canopies were measured using tube solarimeters.Relative humidity in the open and inside the KFG was measured by two solid state humiditysensors. Soil moisture content at three soil depths (30, 60 and 120 em) was measured using thetaprobes. All measurements were done continuously at 30 second time intervals using a datalogger. The data were averaged every 5 minutes and stored in the logger.Detailed continuous measurements taken during a n-hour period (i.e. from 0000 hours on23.06.2001 to 2400 hours 25.06.20)1) were analysed. All three-tree species showed similardiurnal variation patterns in their S8P flow rates with maximum rates occurring between 1300and 1400 hours. Sap flow rate of jak was significantly greater than those of toon a and mahogany,which did not differ significantly. However, the velocity of sap flow was highest in the smallesttree, i.e. mahogany, and decreased with increasing sap wood cross-sectional area. The dailytranspiration rates oftoona and mahogany ranged from 19% to 27%. The incident solar radiationwas highest on the upper canopy tree (i.e. jak), Both the middle canopy (toona) and lowercanopy (mahogany) trees received similar levels of radiation because of the incomplete uppercanopy cover in the KFG. There was a clear linear relationship between daily transpiration of alltree species and the solar radiation levels received by the respective trees. This relationship canbe used to predict the daily water use of a given tree when there is no significant soil waterdeficit.The relative humidity (RH) under both open conditions and within the KFG showed a similarvariation pattern. However, RH within the KFG was slightly higher than that in the open.Transpiration rates of all tree species had negative linear relationships with the respective RHvalues experienced by them.