Implications of climate change and drought on water requirements in a semi-mountainous region of the Vietnamese Mekong Delta.

As the backbone of Vietnam's economy, the country has recently established a number of policies for promoting and investing in smart agriculture in the Mekong Delta, the country's largest agricultural hub, to foster overall socio-economic development. However, water remains a critical constraint for crop production, with progress being hindered by water scarcity and quality issues, and compounded by socio-economic transformation and climate change. Considering these challenges, this study used the CROPWAT model and a wide spectrum of climate change scenarios to investigate future total water demands in the 2030s and 2050s as well as drought levels in two underdeveloped semi-mountainous reservoir catchments, i.e., O Ta Soc and O Tuk Sa in An Giang province. The results suggest that the usable storage capacity of the O Ta Soc reservoir will increase to 650,000 m3 to meet water supply demands under all climate change scenarios and the medium-term, moderate drought conditions. The useable storage capacity of the O Tuk Sa reservoir will also be increased to 880,000 m3 and the irrigation area would see a marked 70% reduction compared to its design irrigation. Under these circumstances, the O Tuk Sa reservoir will continue to supply water under all climate change scenarios and medium-term droughts. As a core element for strategic planning and to ensure efficient management of water resources, the results highlight the importance of estimating potential runoff and rainfall in semi-mountainous reservoir catchments under various drought conditions in order to propose the suitable expansion of the useable water storage capacities.

Body size and digestive system shape resource selection by ungulates: A cross-taxa test of the forage maturation hypothesis.

The forage maturation hypothesis (FMH) states that energy intake for ungulates is maximised when forage biomass is at intermediate levels. Nevertheless, metabolic allometry and different digestive systems suggest that resource selection should vary across ungulate species. By combining GPS relocations with remotely sensed data on forage characteristics and surface water, we quantified the effect of body size and digestive system in determining movements of 30 populations of hindgut fermenters (equids) and ruminants across biomes. Selection for intermediate forage biomass was negatively related to body size, regardless of digestive system. Selection for proximity to surface water was stronger for equids relative to ruminants, regardless of body size. To be more generalisable, we suggest that the FMH explicitly incorporate contingencies in body size and digestive system, with small-bodied ruminants selecting more strongly for potential energy intake, and hindgut fermenters selecting more strongly for surface water.

A study on assessing the urban growth, population, and water resources of Bodrum Peninsula, Turkey.

In recent years, it has been difficult to establish a supply-demand balance between urban growth, increasing population, and existing water resources in many countries. In this study, the Bodrum Peninsula, which is an important tourism center for Turkey, was examined in terms of the relationship between the urban growth of the peninsula, population projections, the need for drinking and potable water, and the availability of the existing water resources. Using the Geographic Information System, it has been determined that the urban growth of the peninsula increased by 11.36% between 1985 and 2010. Urban growth is mostly concentrated in the coastal areas where 2 houses are densely built. The population is expected to increase approximately six times between 2010 and 2060. The amount of drinking and potable water required according to the population projection is 12.38, 26.50, 69.12, and 109.50 hm3/year for 2010, 2030, 2050, and 2060 respectively. The existing water resources of the peninsula will be able to meet the requirements until 2030. In order to meet the water needs of the peninsula until 2055, the Bozalan and Gökçeler dams located nearby as well as the Namnam dam located at mid-range to the peninsular should be built. It is not possible to meet the water needs of the peninsula in 2060 with just the near and medium distance water resources. However, by supplying water from the Akköprü dam located at a further distance, it is possible that 2060 water needs can be met.

Large herbivore assemblages in a changing climate: incorporating water dependence and thermoregulation.

The coexistence of different species of large herbivores (ungulates) in grasslands and savannas has fascinated ecologists for decades. However, changes in climate, land-use and trophic structure of ecosystems increasingly jeopardise the persistence of such diverse assemblages. Body size has been used successfully to explain ungulate niche differentiation with regard to food requirements and predation sensitivity. But this single trait axis insufficiently captures interspecific differences in water requirements and thermoregulatory capacity and thus sensitivity to climate change. Here, we develop a two-dimensional trait space of body size and minimum dung moisture content that characterises the combined food and water requirements of large herbivores. From this, we predict that increased spatial homogeneity in water availability in drylands reduces the number of ungulate species that will coexist. But we also predict that extreme droughts will cause the larger, water-dependent grazers as wildebeest, zebra and buffalo-dominant species in savanna ecosystems - to be replaced by smaller, less water-dependent species. Subsequently, we explore how other constraints such as predation risk and thermoregulation are connected to this two-dimensional framework. Our novel framework integrates multiple simultaneous stressors for herbivores and yields an extensive set of testable hypotheses about the expected changes in large herbivore community composition following climate change.

Hydrological-niche models predict water plant functional group distributions in diverse wetland types.

Human use of water resources threatens environmental water supplies. If resource managers are to develop policies that avoid unacceptable ecological impacts, some means to predict ecosystem response to changes in water availability is necessary. This is difficult to achieve at spatial scales relevant for water resource management because of the high natural variability in ecosystem hydrology and ecology. Water plant functional groups classify species with similar hydrological niche preferences together, allowing a qualitative means to generalize community responses to changes in hydrology. We tested the potential for functional groups in making quantitative prediction of water plant functional group distributions across diverse wetland types over a large geographical extent. We sampled wetlands covering a broad range of hydrogeomorphic and salinity conditions in South Australia, collecting both hydrological and floristic data from 687 quadrats across 28 wetland hydrological gradients. We built hydrological-niche models for eight water plant functional groups using a range of candidate models combining different surface inundation metrics. We then tested the predictive performance of top-ranked individual and averaged models for each functional group. Cross validation showed that models achieved acceptable predictive performance, with correct classification rates in the range 0.68-0.95. Model predictions can be made at any spatial scale that hydrological data are available and could be implemented in a geographical information system. We show the response of water plant functional groups to inundation is consistent enough across diverse wetland types to quantify the probability of hydrological impacts over regional spatial scales.

Remote Sensing for Crop Water Management: From ET Modelling to Services for the End Users.

The experiences gathered during the past 30 years support the operational use of irrigation scheduling based on frequent multi-spectral image data. Currently, the operational use of dense time series of multispectral imagery at high spatial resolution makes monitoring of crop biophysical parameters feasible, capturing crop water use across the growing season, with suitable temporal and spatial resolutions. These achievements, and the availability of accurate forecasting of meteorological data, allow for precise predictions of crop water requirements with unprecedented spatial resolution. This information is greatly appreciated by the end users, i.e., professional farmers or decision-makers, and can be provided in an easy-to-use manner and in near-real-time by using the improvements achieved in web-GIS methodologies (Geographic Information Systems based on web technologies). This paper reviews the most operational and explored methods based on optical remote sensing for the assessment of crop water requirements, identifying strengths and weaknesses and proposing alternatives to advance towards full operational application of this methodology. In addition, we provide a general overview of the tools, which facilitates co-creation and collaboration with stakeholders, paying special attention to these approaches based on web-GIS tools.

A review of the ecohydrology of the Sakumo wetland in Ghana.

The Sakumo wetland is an internationally recognized Ramsar site located in a largely urban area and provides essential ecological and social services to wetland community dwellers. Despite its importance, the wetland has over the years been subjected to human interference resulting in considerable risks of deteriorating water quality, biodiversity loss, and drying up of most parts of the wetland. The conversion of land for residential and agricultural uses has significantly altered the hydrological characteristics of the land surface and modified pathways and flow of water into the wetland. Other drivers identified included drainage (mainly as runoff from agricultural farms), anthropogenic pressure (waste discharge) due to infrastructure development associated with urbanization, chemical contamination as a result of industrial and household pollution, and unsustainable fishing practices (overfishing). The purpose of the study was to review some of the physical and chemical properties of the Sakumo wetland on the changing wetland resources with emphasis on water quality. Rapid urbanization, industrialization, and overexploitation of wetland resources were identified as key causative factors affecting the wetland functions. Their effects on the wetland among others include increased nutrient and toxic chemical load which has resulted in reduced wetland surface water quality and decrease in species diversity. pH of the wetland waters was generally alkaline which is characteristic of water bodies influenced by seawater under oxygenated conditions. The increasing trends of electrical conductivity, phosphates, ammonia, nitrate, and nitrite, though small, point to deteriorating water quality in the wetland. The lagoon water was observed to be heavily polluted with nutrients particularly phosphate. The sequence of nutrient in the wetland was found to be in the order of PO4-P>NH3-N>NO3-N>NO2-N. These, if not checked, will result in further deterioration of the wetland function. In order to protect the wetland structure and function, it is recommended that a determination for both surface water and groundwater (quality and quantity) components of the ecological reserve (aquatic ecosystem) as well as the basic human need should be undertaken. In addition, a complete hydrological study of the wetland must be done. This will enable a well-balanced water allocation scheme to all users while still ensuring long-term survival and sustainability of the wetland.

Whole body sweat rate prediction: indoor treadmill and cycle ergometer exercise.

This article describes the development and validation of accurate whole body sweat rate prediction equations for individuals performing indoor cycle ergometer and treadmill exercise, where power output can be measured or derived from simple inputs. For cycle ergometry, 112 trials (67 participants) were used for model development and another 56 trials (42 participants) for model validation. For treadmill exercise, 171 trials (67 participants) were used for model development and another 95 trials (63 participants) for model validation. Trials were conducted over a range of dry-bulb temperature (20°C to 40°C), relative humidity (14% to 60%), and exercise intensity (∼40% to 85% of peak aerobic power) conditions, which were matched between model development and model validation. Whole body sweat rates were measured, and proprietary prediction models were developed (accounting for all relevant biophysical factors) and then validated. For model validation, mean absolute error for predicted sweating rate was 0.01 and 0.02 L·h-1 for cycle and treadmill trials, respectively. The 95% confidence intervals were modest for cycle ergometer (+0.25 and -0.22 L·h-1) and treadmill exercise (+0.33 and -0.29 L·h-1). The accounted for variance between predicted and measured values was 92% and 78% for cycle and treadmill exercise, respectively. Bland-Altman analysis indicated that zero and one predicted value exceeded the a priori acceptable level of agreement (equivalent to ±2% of total body mass in 3 h) for cycle and treadmill exercise, respectively. There were fewer trials with female subjects, but their values did not differ from those expected for males. This is the foremost study to develop and validate whole body sweat rate prediction equations for indoor treadmill and cycle ergometer exercise of moderate to high intensity. These prediction equations are publicly available for use (https://sweatratecalculator.com).NEW & NOTEWORTHY This study presents the development of new proprietary whole body sweat rate prediction models for people exercising indoors on a cycle ergometer or treadmill using simple input parameters and delivered through a publicly available online calculator: https://sweatratecalculator.com. In an independent validation group, the predictive models for both indoor cycling and treadmill exercise were accurate across moderate to high exercise intensities in temperate to hot conditions. These equations will enable individualized hydration management during physical training and exercise physiology experiments.

Whole body sweat rate prediction: outdoor running and cycling exercise.

Our aim was to develop and validate separate whole body sweat rate prediction equations for moderate to high-intensity outdoor cycling and running, using simple measured or estimated activity and environmental inputs. Across two collection sites in Australia, 182 outdoor running trials and 158 outdoor cycling trials were completed at a wet-bulb globe temperature ranging from ∼15°C to ∼29°C, with ∼60-min whole body sweat rates measured in each trial. Data were randomly separated into model development (running: 120; cycling: 100 trials) and validation groups (running: 62; cycling: 58 trials), enabling proprietary prediction models to be developed and then validated. Running and cycling models were also developed and tested when locally measured environmental conditions were substituted with participants' subjective ratings for black globe temperature, wind speed, and humidity. The mean absolute error for predicted sweating rate was 0.03 and 0.02 L·h-1 for running and cycling models, respectively. The 95% confidence intervals for running (+0.44 and -0.38 L·h-1) and cycling (+0.45 and -0.42 L·h-1) were within acceptable limits for an equivalent change in total body mass over 3 h of ±2%. The individual variance in observed sweating described by the predictive models was 77% and 60% for running and cycling, respectively. Substituting measured environmental variables with subjective assessments of climatic characteristics reduced the variation in observed sweating described by the running model by up to ∼25%, but only by ∼2% for the cycling model. These prediction models are publicly accessible (https://sweatratecalculator.com) and can guide individualized hydration management in advance of outdoor running and cycling.NEW & NOTEWORTHY We report the development and validation of new proprietary whole body sweat rate prediction models for outdoor running and outdoor cycling using simple activity and environmental inputs. Separate sweat rate models were also developed and tested for situations where all four environmental parameters are not available, and some must be subsequently estimated by the user via a simple rating scale. All models are freely accessible through an online calculator: https://sweatratecalculator.com. These models, via the online calculator, will enable individualized hydration management for training or recreational cycling or running in an outdoor environment.

Establishment of watershed ecological water requirements framework: A case study of the Lower Yellow River, China.

It is of great practical significance to ensure ecological water requirements (EWRs) for the maintenance of river health and the sustainable development of human socioeconomics. How to scientifically determine the comprehensive EWRs and estimate the uncertainty of hydro-ecological tools performed in the process of conducting remains one of the most important yet most complicated issues. In this study, the ecological water requirements framework (EWRsF) of the Lower Yellow River (LYR), which considers instream ecological base flow, survival and reproduction of indicator fish species, equilibrium of erosion and siltation and ecological function of the estuary, was constructed by integrating hydrological, hydraulic and ecological habitat methods. The framework contains three crucial components - determination of instream EWRs and estuarine EWRs, uncertainty analysis of hydro-ecological tools. For instream ecological base flow, we proposed an improved Tennant method, which took into account both seasonality and sediment transport characteristics of the LYR, and could better reflect the actual hydrological regime. For the hydrological ecological response relationship of indicator fish species, we estimated the uncertainty of the model output of River2D to improve its credibility of the simulation results. The results demonstrated that: 1) Two-grade intra-annual monthly EWRs process of suitable and minimum for four instream sections and estuary area were obtained. The flood season (June-October) is the period with the largest proportion of intra-annual instream EWRs, whereas in estuary area, is the spawning period (April-July) of dominant species. 2) The uncertainty of HSI curves directly leads to the uncertainty of model output. Although the shape and position of the WUA curve can be uncertain, it does not affect the judgment of EWRs threshold. 3) The research results can provide scientific basis for water resource management decision-making in the LYR. Additionally, the ideas also have reference significance for similar basins.

Does Climate Change Increase Crop Water Requirements of Winter Wheat and Summer Maize in the Lower Reaches of the Yellow River Basin?

With increasing water resources stress under climate change, it is of great importance to deeply understand the spatio-temporal variation of crop water requirements and their response to climate change for achieving better water resources management and grain production. However, the quantitative evaluation of climate change impacts on crop water requirements and the identification of determining factors should be further explored to reveal the influencing mechanism and actual effects thoroughly. In this study, the water requirements of winter wheat and summer maize from 1981 to 2019 in the lower reaches of the Yellow River Basin were estimated based on the Penman-Monteith model and crop coefficient method using daily meteorological data. Combined with trends test, sensitivity and contribution analysis, the impacts of different meteorological factors on crop water requirement variation were explored, and the dominant factors were then identified. The results indicated that the temperature increased significantly (a significance level of 0.05 was considered), whereas the sunshine duration, relative humidity and wind speed decreased significantly from 1981 to 2019 in the study area. The total water requirements of winter wheat and summer maize presented a significant decreasing trend (-1.36 mm/a) from 1981 to 2019 with a multi-year average value of 936.7 mm. The crop water requirements of winter wheat was higher than that of summer maize, with multi-year average values of 546.6 mm and 390.1 mm, respectively. In terms of spatial distribution patterns, the crop water requirement in the north was generally higher than that in the south. The water requirements of winter wheat and summer maize were most sensitive to wind speed, and were less sensitive to the minimum temperature and relative humidity. Wind speed was the leading factor of crop water requirement variation with the highest contribution rate of 116.26% among the considered meteorological factors. The results of this study will provide important support for strengthening the capacity to cope with climate change and realizing sustainable utilization of agricultural water resources in the lower reaches of the Yellow River Basin.

Determination of crop coefficient for chufa crop (Cyperus esculentus L. var. sativus Boeck.) for sustainable irrigation scheduling.

Chufa is a traditional crop in L'Horta de València (Spain), a historical agricultural system that has been recognised in the register of Globally Important Agricultural Heritage Systems, managed by the Food and Agriculture Organization of the United Nations (FAO), and is one of the six protected Mediterranean and metropolitan horticultural fields as per the European Environment Agency. Chufa is a horticultural crop cultivated for its tubers. Our team has carried out different studies to improve the sustainability of chufa crop, particularly the efficiency of irrigation water use; however, the complete irrigation water requirements remain unknown. Therefore, the main aim of this study was to determine the crop coefficient values for chufa crop along its crop cycle using a smart field weighing lysimeter for three consecutive seasons and to determine its irrigation water requirements. The single crop coefficient values are 0.32, 1.40, and 0.80 for the initial stage, mid-season stage, and end of the late season stage, respectively for local conditions and 1.24 and 0.73 for mid- and late season stages, respectively for standard conditions. FAO segmented and second-order polynomial functions are presented to describe the crop coefficient evolution throughout the cycle, and could be used for irrigation scheduling and may lead to important water savings. The average seasonal net irrigation water requirement for chufa crop was approximately 640 mm, representing around 57% of the irrigation depth usually applied by chufa growers. The water savings that may be achieved by the adjustment of irrigation water with irrigation water requirements, using the crop coefficient, would improve, to a great extent, the sustainability of the L'Horta de València historical agricultural system, in view of the water scarcity resulting from climate change. This sustainable irrigation scheduling will improve the ecosystem indices, which have been altered by the application of over-irrigation, in the area.

Effects of lipid and starch supplementation as water intake mitigation techniques on performance and efficiency of nursing Holstein calves.

Exploring alternative supplementation sources capable of maximizing feed and water efficiency in nursing Holstein calves is often ignored. The goals herein involve investigating the effects of two isoenergetic supplements on a nonmedicated milk replacer diet on total water intake, milk water intake, fresh water intake, feed intake parameters, and performance of Holstein nursing bull calves. Twenty-three animals (body weight [BW] = 94.67 ± 12.07 kg, age = 67 days old) were randomly assigned to one of three treatments for 68 days: control (CON; ad libitum milk replacer, n = 7), carbohydrate supplement (CHO; corn starch on top of ad libitum milk replacer-based diet, n = 8), or lipid supplement (FAT; menhaden fish oil on top of ad libitum milk replacer-based diet, n = 8). The isoenergetic supplementation consisted of 3% menhaden fish oil addition on DM basis for FAT. This was matched energetically with corn starch for the CHO group resulting in a 7% composition in DM basis. All animals were provided free access to mineral mix and 120 g daily dried microbrewer's spent grains (BG). Data were analyzed with the GLMMIX procedure of SAS in a completely randomized design with the diets as a fixed effect. Dry matter intake (DMI) adjusted by average daily gain (ADG; DMI/ADG) resulted in significantly lower values for supplemented groups with CON = 2.48, CHO = 2.38, and FAT = 2.27 kg/kg (ADG) (P = 0.033). Energy intake values were lower for CON when analyzing metabolizable energy intake (P < 0.0001), net energy intake for maintenance (P < 0.0001), and net energy intake for gain (P < 0.0001), followed by CHO, and then FAT. Total water intake (P < 0.0001), milk water intake (P < 0.0001), and fresh water intake (P < 0.0001) all resulted in CHO consuming 0.5 L or less water than the other two treatments. Energy requirements as digestible energy (P < 0.0001), metabolizable energy (P < 0.0001), net energy for maintenance (P < 0.0001), and net energy for gain (P < 0.0001) were lower for CHO, followed by CON, and then FAT having the highest requirements. Similar results were observed for residual feed (RFI; P = 0.006) and residual water intakes (RTWI; P = 0.902). Ultimately, no performance differences were detected with regards to BW (CON = 146.71, CHO = 146.25, and FAT = 150.48 kg; P > 0.1). These results indicate that lipid-based and starch-based supplementation can potentially increase feed efficiency and decrease voluntary water intake without adversely affecting performance.

Adapting water resources systems to climate change in tropical areas: Ecuadorian coast.

Climate change is expected to increase rainfall and temperature in the tropical areas of the Ecuadorian coast. The increase in temperature will also increase evapotranspiration therefore, future water balance on Ecuadorian coast will have a slight variation. Changes in precipitation patterns and evapotranspiration will produce an increase in the water requirements for current crops, so an imbalance in the water resources systems between natural resources and water demands is expected. This study presents water resources management as an adaptation measure to climate change for reducing vulnerability in tropical areas. Twelve bias-corrected climate projections are used, from: two AR5 General Circulation Models (GCMs), two Representative Concentration Pathways, 4.5-8.5 scenarios, and three time periods, short-term (2010-2039), medium-term (2040-2069) and long-term (2070-2099). These data were incorporated into the Lumped Témez Hydrological Model. Climate change scenarios predict for the long-term period both a mean rainfall and temperature increases up to 22%-2.8 °C, respectively. Besides, the potential evapotranspiration will increase until 12% by Penman-Monteith method and 60% by Thornthwaite method. Therefore, natural water resources will finally have an increase of 19% [8-30%]. Additionally, water requirements for crops will increase around 4% and 45%. As this research shows, in tropical regions, currently viable water resources systems could become unsustainable under climate change scenarios. To guarantee the water supply in the future additional measures are required as reservoir operation rules and irrigation efficiency improvement of system from 0.43 to 0.65, which it involves improving the distribution and application system. In study area future irrigation areas have been estimated for 13,268 ha, which under climate change scenarios is unsustainable, only 11,500 ha could be expanded with a very high irrigation efficiency of 0.73. Therefore, in tropical areas the effect of climate change on expansion projects for irrigated areas should be considered to ensure the functioning systems.

Claims of anomalously long fasting: An assessment of the evidence from investigated cases.

BACKGROUND: Throughout history and to the present day, there have been reports of people claiming inedia, i.e., an anomalous long-term abstinence from food or from food and fluid. Some were isolated and monitored and their abstinences confirmed. This raises the question of whether there may be an anomaly with wide implications that science has overlooked. On the other hand, there have been cases of exposed fraud. The reports on the studies are scattered and it can be difficult to judge their rigor and the strength and implications of their evidence. A critical evaluation seems useful. OBJECTIVES: The objectives were to obtain an overview of investigated cases of claimed inedia, to assess the anomaly of the claims and study results, to assess the quality of the studies, and to identify deception methods to inform future safeguards. METHOD: I developed criteria for differentiating normal from anomalous nutrition and fasting and for assessing the quality of inedia studies. Studies found through a systematic search were then assessed and the features of cases of fraud extracted. RESULTS: 47 eligible investigations of 38 claimants were found. Out of the 38 cases, results were assessed as (seemingly) anomalous in 11, with nine cases of monitored food and fluid deprivation ranging from 14 to 68 days (median 28 days), and two cases of food deprivation for 365 and 411 days. In 17 cases, anomaly was assessed as not confirmed due to issues with study design or reporting. Fraud was established in 10 cases. Deception methods were creative. Post-1900 studies were also assessed for quality. Quality was not considered adequate in any. CONCLUSIONS: I consider the evidential status of inedia unconfirmed as no assessed study had both anomalous findings and impeccable quality. However, quality was often downgraded due to reporting issues and it cannot be concluded in reverse that all claimants with anomalous results were able to deceive the investigators. The results of many studies are curious and demand further research. The conducted analysis provides guidance for improving rigor and transparency in future studies.

Climate change signals in the historical water footprint of wheat production in Zimbabwe.

Climate change has been posited as the biggest threat to crop productivity in agro-systems, yet its impact on the water footprints of crop production for many regions remains uncertain. This study sought to determine evidence of historical climate change (1980-2010) and its resultant impact on the blue water footprint of winter wheat production in Zimbabwe. The analysis involved assessing the impact of climate change on wheat yield and crop water requirements, the key factors determining the blue water footprint. The CROPWAT model and the global water footprint assessment (WFA) standard were used to calculate the blue water footprint. Multiple linear regression was used to correlate climate variables to wheat yield, crop water requirements and the blue water footprint. Results show a significant (p < 0.05) warming of temperatures in the country's main wheat growing areas. Crop water requirements for winter wheat decreased by 4.88%, due to positive and negative trends in humidity and wind speed respectively. Between 1980 and 2000 the coupled effects of solar radiation at anthesis and maximum temperatures in July, August and September reduced wheat yields by 6.65%. The cumulative effects of climate change on crop water requirements and wheat yields increased the blue water footprint by 4%. The results of the study suggest that climate change and agricultural management factors might be equally responsible for the increase in the blue water footprint.

Effects of temperature, precipitation and carbon dioxide concentrations on the requirements for crop irrigation water in China under future climate scenarios.

Maize, rice, wheat and soybean-the major staple food crops in China-have a crucial role in national food security and economic development. Predictions of changes in the requirements for irrigation water in food crop production under climate change may provide scientific support for the optimum allocation of water resources and measures to mitigate climate change. We conducted a spatial grid-based analysis using projections of future climate generated by a bias-correction and spatial disaggregation multi-model ensemble for three representative concentration pathway scenarios (RCP2.6, RCP4.5 and RCP8.5) adopted by the fifth phase of the Coupled Model Intercomparison Project. We investigated the effects of climate change associated with increasing temperature, changed precipitation and increased concentrations of atmospheric carbon dioxide (CO2) on the irrigation water requirements of maize, rice, wheat and soybean in China at the end of the 21st century (2081-2100). Our results indicate that the irrigation water requirements of maize and wheat are driven by temperature and especially by CO2 concentrations in the northwest interior area as a result of the low rainfall and high rates of evaporation; the irrigation water requirement of soybean is influenced by a combined effect of temperature, precipitation and CO2 concentration, whereas the irrigation water requirement for rice is dominated by precipitation alone in the southern coastal region, which has high rainfall. The irrigation water requirements of crops decrease mainly as a result of the beneficial effects of CO2 on plant growth in China. The regions requiring vast amounts of irrigation water as a result of climate change are mainly concentrated in northwestern China. The effects of climate change affect the requirement for irrigation water, especially under high-emission scenarios, and should be studied further to design appropriate adaptation strategies for the management of agricultural water to maintain the sustainable development of agriculture.

Minimizing irrigation water demand: An evaluation of shifting planting dates in Sri Lanka.

Climate change coupled with increasing demands for water necessitates an improved understanding of the water-food nexus at a scale local enough to inform farmer adaptations. Such assessments are particularly important for nations with significant small-scale farming and high spatial variability in climate, such as Sri Lanka. By comparing historical patterns of irrigation water requirements (IWRs) to rice planting records, we estimate that shifting rice planting dates to earlier in the season could yield water savings of up to 6%. Our findings demonstrate the potential of low-cost adaptation strategies to help meet crop production demands in water-scarce environments. This local-scale assessment of IWRs in Sri Lanka highlights the value of using historical data to inform agricultural management of water resources when high-skilled forecasts are not available. Given national policies prioritizing in-country production and farmers' sensitivities to water stress, decision-makers should consider local degrees of climate variability in institutional design of irrigation management structures.

Olive Cultivation in the Southern Hemisphere: Flowering, Water Requirements and Oil Quality Responses to New Crop Environments.

Olive (Olea europaea L.) is a crop well adapted to the environmental conditions prevailing in the Mediterranean Basin. Nevertheless, the increasing international demand for olive oil and table olives in the last two decades has led to expansion of olive cultivation in some countries of the southern hemisphere, notably in Argentina, Chile, Perú and Australia. While the percentage of world production represented by these countries is still low, many of the new production regions do not have typical Mediterranean climates, and some are located at subtropical latitudes where there is relatively little information about crop function. Thus, the primary objective of this review was to assess recently published scientific literature on olive cultivation in these new crop environments. The review focuses on three main aspects: (a) chilling requirements for flowering, (b) water requirements and irrigation management, and (c) environmental effects on fruit oil concentration and quality. In many arid and semiarid regions of South America, temperatures are high and rainfall is low in the winter and early spring months compared to conditions in much of the Mediterranean Basin. High temperatures have often been found to have detrimental effects on olive flowering in many olive cultivars that have been introduced to South America, and a better understanding of chilling requirements is needed. Lack of rainfall in the winter and spring also has resulted in an urgent need to evaluate water requirements from the flower differentiation period in the winter to early fruit bearing. Additionally, in some olive growing areas of South America and Australia, high early season temperatures affect the timing of phenological events such that the onset of oil synthesis occurs sooner than in the Mediterranean Basin with most oil accumulation taking place in the summer when temperatures are very high. Increasing mean daily temperatures have been demonstrated to decrease fruit oil concentration (%) and negatively affect some aspects of oil quality based on both correlative field studies and manipulative experiments. From a practical standpoint, current findings could be used as approximate tools to determine whether the temperature conditions in a proposed new growing region are appropriate for achieving sustainable oil productivity and quality.

Ajuste del coeficiente basal de cultivo (Kcb) de frijol (Phaseolus vulgaris) mediante teledetección

Para realizar un manejo eficiente del agua en la agricultura es necesario conocer los requerimientos hídricos del cultivo, lo cual, se puede realizar de manera sencilla y rápida, con la ayuda de cámaras convencionales. En este estudio, se determinaron los requerimientos hídricos de un cultivo de frijol (variedad DIACOL CALIMA G4494), sembrado en CIAT, Palmira - Valle del Cauca, Colombia, mediante la estimación de la curva del coeficiente basal de cultivo (Kcb), derivada de la curva de fracción de cobertura vegetal (Fcv). Para determinar la curva de fracción de cobertura vegetal, se emplearon imágenes tomadas con una cámara digital en el espectro visible (RGB), a baja altura (menos de 3 m). Las necesidades hídricas del cultivo de frijol, se calcularon empleando los valores del coeficiente basal de cultivo derivados junto con la modelación FAO-56. Los resultados indican que la curva de Kcb ajustada por fotografía fue diferente a la curva estándar presentada en la publicación FAO-56 para frijol, mostrando, principalmente, diferencia en la duración de las etapas y los valores de Kcb, en estas etapas. En cuanto a las necesidades hídricas, al emplear la curva de Kcb ajustada por fotografías, se evidencia que el cultivo requiere más agua en las etapas media y final, para evitar estrés hídrico en las plantas.

To carry out efficient water management in agriculture, it is necessary to know the water requirements of the crop, which can be done easily and quickly with the help of conventional cameras. In this study, the water requirements of a bean crop (DIACOL CALIMA G4494 variety) planted in CIAT, Palmira - Valle del Cauca, Colombia, were determined by estimating the curve of the basal crop coefficient (Kcb) derived from the vegetation cover fraction curve (Fcv). To determine the vegetation cover fraction curve, images taken with a digital camera in the visible spectrum (RGB) at low height (less than 3m) were used. The water needs of the bean crop were calculated using the basal crop coefficient values derived together with the FAO-56 modelling. The results indicate that the Kcb curve adjusted by photography was different from the standard curve presented in the publication FAO-56 for beans, mainly showing a difference in the duration of the stages and the Kcb values in these stages. Regarding water needs, when using the Kcb curve adjusted by photographs, it is evident that the crop requires more water in the middle and final stages, to avoid water stress in the plants.