The Impact of Dry Years on Crop Water Requirements in Eastern England

Agricultural water demand is weather and climate driven. Irrigated crop production which makes the largest agricultural demands is highly seasonal, water only being required in a few summer months. A 'droughtiness'factor which is based on crop type and potential soil moisture deficit indicates large differences in the amount and timing of water demand for different crops. Soils with low water retention capacity are shown to be marginal for the potato crop unless irrigation is available in these areas. Economic data are presented which indicate that potato production realizes a considerable benefit from investment in irrigation, but this leads to inertia in the relocation of agricultural production centres in dry years. It is concluded that investment in on-farm winter water storage for irrigation should be a priority investment in eastern England.     

Reuse of treated municipal wastewater in irrigation: a case study from Lebanon and Jordan

In this study, we present the results of scenarios where secondary‐treated municipal wastewater was used for table grapes irrigation in the region of Ablah, Bekaa valley in Lebanon, and fodder crops irrigation (vetch and barley) in the region of Ramtha in Jordan. In Lebanon, we carried out experiments to assess the response of drip‐irrigated table grapes grown under two water quality regimes (Freshwater (FW) and treated wastewater (TW) and two water levels (100% of evapotranspiration (ETc) and 75% of ETc). While in Jordan, we carried out experiments to assess the response of drip‐irrigated fodder crops considering 4 irrigation levels (Q1: Rain fed; Q2: 80% of ETc; Q3: 100% of ETc; Q4: 120% of ETc) and three crop patterns (C1: Barley 100%; C2: Vetch 100%; C3: Mix 50% barley and 50% vetch). Based on the production and quality components, table grapes were successfully grown on plots that are supplied with TW. Fodder crops were successfully grown using TW with remarkable increase in biomass and grain yield production for the irrigated treatments.     

Projected water consumption in future global agriculture: scenarios and related impacts

Global stress on water and land resources is increasing as a consequence of population growth and higher caloric food demand. Many terrestrial ecosystems have already massively been degraded for providing agricultural land, and water scarcity related to irrigation has damaged water dependent ecosystems. Coping with the food and biomass demand of an increased population, while minimizing the impacts of crop production, is therefore a massive upcoming challenge. In this context, we developed four strategies to deliver the biotic output for feeding mankind in 2050. Expansion on suitable and intensification of existing areas are compared to assess associated environmental impacts, including irrigation demand, water stress under climate change, and the productivity of the occupied land. Based on the agricultural production pattern and impacts of the strategies we identified the trade-offs between land and water use. Intensification in regions currently under deficit irrigation can increase agricultural output by up to 30%. However, intensified crop production causes enormous water stress in many locations and might not be a viable solution. Furthermore, intensification alone will not be able to meet future food demand: additionally, a reduction of waste by 50% along the food supply chain or expansion of agricultural land is required for satisfying current per-capita meat and bioenergy consumption. Suitable areas for such expansion are mainly located in Africa, followed by South America. The increased land stress is of smaller concern than the water stress modeled for the intensification case. Therefore, a combination of waste reduction with expansion on suitable pastures generally results as the best option, along with some intensification on selected areas. Our results suggested that minimizing environmental impacts requires fundamental changes in agricultural systems and international cooperation, by producing crops where it is most environmentally efficient and not where it is closest to demand or cheapest.     

Evaluation of the impact of various agricultural practices on nitrate leaching under the root zone of potato and sugar beet using the STICS soil-crop model

The quaternary aquifer of Vitoria-Gasteiz (Basque Country, Northern Spain) is characterised by a shallow water table mainly fed by drainage water, and thus constitutes a vulnerable zone in regards to nitrate pollution. Field studies were performed with a potato crop in 1993 and a sugar beet crop in 2002 to evaluate their impact on nitrate leaching. The overall predictive quality of the STICS soil-crop model was first evaluated using field data and then the model was used to analyze dynamically the impacts of different crop management practices on nitrate leaching. The model was evaluated (i) on soil nitrate concentrations at different depths and (ii) on crop yields. The simulated values proved to be in satisfactory agreement with measured values. Nitrate leaching was more pronounced with the potato crop than with the sugar beet experiment due to i) greater precipitation, ii) lower N uptake of the potato crop due to shallow root depth, and iii) a shorter period of growth. The potato experiment showed that excessive irrigation could significantly increase nitrate leaching by increasing both drainage and nitrate concentrations. The different levels of N-fertilization examined in the sugar beet study had no notable effects on nitrate leaching due to its high N uptake capacity. Complementary virtual experiments were carried out using the STICS model. Our study confirmed that in vulnerable zones agricultural practices must be adjusted, that is to say: 1) N-fertilizer should not be applied in autumn before winter crops; 2) crops with low N uptake capacity (e.g. potatoes) should be avoided or should be preceded and followed by nitrogen catch crops or cover crops; 3) the nitrate concentration of irrigation water should be taken into account in calculation of the N-fertilization rate, and 4) N-fertilization must be precisely adjusted in particular for potato crops.     

Screening of 47 organic microcontaminants in agricultural irrigation waters and their soil loading

Reclaimed water usage for crop irrigation is viewed both as an excellent sustainable water source and as a potential entrance for emerging organics into the food chain. This concern is backed by the already documented pollutant crop uptake potential. In the present study, irrigation waters used in agricultural fields (Torroella de Montgri, NE Spain) were screened for 47 analytes in a two year study (2007-2008). A total of 26 contaminants belonging to different chemical classes namely, pesticides, pharmaceuticals, personal care products, phenolic estrogens, antioxidants and disinfection by-products, were detected. Marked differences in concentration trends for the different chemical classes were evidenced from 2007 to 2008, and attributed to a persistent drought endured by the region in 2008. Also, loading mass rates of chemical classes were estimated based on crop irrigation regimes and they ranged from 0.8 to 121.3 g ha⁻¹ per crop cycle. These values were contrasted with those obtained for other water sources from countries where crop irrigation is commonly practiced. Finally, crops grown under these irrigation regimes, namely alfalfa and apple, were analyzed and 5 anthropogenic compounds were identified and quantitated, whose concentrations ranged from 13.9 to 532 ng g⁻¹ (fresh weight).     

Stochastic time-cost optimization using non-dominated archiving ant colony approach

This article employs a non-dominated archiving ant colony approach to solve the stochastic time-cost trade-off optimization problem. The model searches for non-dominated solutions considering total duration and total cost of the project as two objectives. In order to expect more realistic outcomes for the time-cost trade-off problem, uncertainties in time and cost of the project should be taken into account. Fuzzy sets theory is used to answer for uncertainties in time and cost of the project. The model embeds the α-cut approach to account for accepted risk level of the project manager. Left and right dominance ranking method is used for finding non-dominated solutions. The ranking method employs decision maker's optimism using β concept. The performance of the model is tested according to performance metrics for multi-objective evolutionary algorithms proposed in the literature. The results show that the algorithm is adequately reliable. A case study is solved to show the application of the proposed model for the uncertain time-cost trade-off problem.     

The use of town refuse ash in urban agriculture around Jos, Nigeria: health and environmental risks

This paper reports on a study that examines the health and environmental risks of using town refuse ash in urban vegetable production in Jos, Nigeria, in terms of heavy metal accumulation in the food chain. Soil and crop samples, collected from five study farms, and samples of the river water used for irrigation, were analysed for seven heavy metals Fe, Mn, Zn, Cu, Ni, Cd and Pb. On the basis of the field data the paper discusses: (1) the potential soil deficiencies and toxicities; (2) the probable links between soil heavy metal levels and fertilisation practices; (3) the heavy metal concentrations in crop tissue in relation to crop growth and human health. The findings suggest that soil concentrations of the seven metals fall within 'typical' soil levels, and that there should not be any problems of either toxicities or deficiencies for crop growth. There was evidence of slight accumulation of Zn, Cu and Cd on some of the farms with a history of town refuse ash use. However, in all farms lettuce crops contained very large concentrations of Fe, and Pb concentrations that were 20 to 40 times higher than the WHO/FAO maximum recommended level in leafy vegetables for human consumption. The Cd content of carrot tissue was 10 times higher than the WHO/FAO recommended limit. The relatively small number of soil and crop samples precluded any formal attempt at correlating the concentrations of heavy metals found in the vegetable crops with the farm levels. Nevertheless, the data suggested that these were not linked. The paper goes on to consider various potential sources of the metals found in the crops, including irrigation water, town refuse ash and air-borne dust, and discusses additional health and environmental risks pertaining to the use of town refuse ash. Undoubtedly, the heavy Pb and Cd contamination of certain crops indicates the urgent need for future studies to ascertain the precise source of these metals, and although the practice of using town refuse ash does not appear to have resulted in large-scale contamination of soil in the farming area, there are a number of unsafe practices associated with it that call for the identification of strategies for the safe utilisation of urban waste in Jos.     

Methods of stochastic structural dynamics

A concise review is given of the analytical methods of stochastic structural dynamics which deals with structural systems under time-varying random excitation. Included in the review are both linear and nonlinear structures and both parametric and non-parametric random excitations. Mathematically, parametric excitations appear in the coefficients for the unknowns in the equations of motion, whereas non-parametric excitations appear as inhomogeneous terms on the right hand side. Physically, random parametric excitations represent the variation of structural properties with time; therefore, they can affect the stability of structural response. Approximate methods are described for those cases for which exact solutions are presently not available.     

Cyanobacterial toxins: an emerging threat in South African irrigation water

The deterioration of water quality is a serious concern for a water scarce‐country like South Africa (SA). This article looks at the risks posed by the common practice of using surface waters to irrigate crops, as these are usually contaminated with harmful cyanobacteria and cyanotoxins which can be bio‐accumulated by plants. In addition to cyanotoxins, SA waters are also heavily impacted by other pollutants such as toxic metals, salts and high electrical conductivity. The consumption of food contaminated with cyanotoxins is a growing human health concern for countries like SA which are faced with surface water eutrophication‐related challenges. The country also lacks research on human exposure to cyanotoxins via irrigated crops and regulations to manage cyanotoxins in irrigation water. Such lack of data and policies thus prompts an urgent need for local evidence‐based research to guide policies and guidelines on cyanotoxins in irrigation water, food plants and water used for livestock.     

Uncertainties in probabilistic numerical analysis of structures and solids-Stochastic finite elements

The main sources of uncertainties involved in the analysis of structures and solids are shown and the tools available to deal with them. While trying to cover the complete modeling process, ranging from the problem formulation via the mathematical model all the way to the numerical approximation, we have tried to expose areas in need of further research. The techniques and methods involved in stochastic modeling are explained in somewhat more detail, as they are newer and less known than those used for the deterministic modeling.     

防治次生盐碱化的灌区水资源利用研究——以松原灌区为例

为改善松原灌区规划区盐碱化现状、防止灌区运行后土壤发生次生盐碱化的目标,对灌区地下水、地表水联合调度进行模拟,以盐碱化临界埋深为标准并结合水盐均衡差对模拟计算结果分析后表明,采用考虑实际条件的井渠结合灌溉方案既能淋滤土壤中的盐份又有效地控制潜水埋深减少土壤返盐,兼顾生态环境效益与经济效益.     

边坡极限承载力的下限分析法及其可靠度理论

应用极限分析的下限法求解边坡的极限承载力,供助于有限单元法和线性规划法,可以较容易地建立静力许可场,并进而求得极限荷载的最大值。该法具有严格的理论基础,克服了人工建立静力场的困难。对无自重的边坡极限承载力问题,应用该方法得到的数值解与经典塑性力学得到的理论解的比较说明了本法的正确性和通用性。针对建立在极限平衡理论基础上的可靠度分析方法的不足,利用蒙特卡罗方法获得了边坡承载力下限解的可靠度指标。为克服蒙特卡罗方法数据量大、经济性差的特点,应用随机规划的区间概率法求取了边坡承载力的可靠度指标,该法具有坚实的数学基础和鲜明的物理意义。     

Modeling and analysis of uncertainties for risk-informed decisions in infrastructures engineering

Engineers deal with uncertainties in all their activities, and must often make decisions under conditions of uncertainty and risk. Infrastructures engineering is no exception—design codes are developed to ensure a desired level of safety and performance, or to ensure a specified operational life with a prescribed level of reliability; the required decisions must often be formulated without complete information and thus contain uncertainties. In considering uncertainties, it is important to recognize two broad types; namely, the aleatory type which is associated with natural randomness and the epistemic type which is associated with imperfect knowledge. Proposed here is a framework for the proper modeling and treatment of each type of uncertainty in the formulation of risk-informed engineering decisions. The concepts are illustrated with applications to bridges and offshore marine structures.     

Performance,reliability and uncertainty of total phosphorus models for lakes—II. Stochastic analyses

Water quality problems in lakes are frequently analyzed with the assistance of models that simulate the dynamic behavior of total phosphorus. Part I of this series used deterministic methods to evaluate the performance and reliability of models with different formulations and mechanisms. Complex models are often amenable to accurate calibration but may be sensitive to uncertainties in the model coefficients and errors in measured lake data. This paper uses stochastic methods (Monto Carlo) to examine the supposition that the appropriate level of model complexity depends on the accuracy of measured data and the uncertainty associated with model coefficients. Three total phosphorus models are used to test the methodology for Shagawa Lake.     

Virus survival on vegetables spray-irrigated with wastewater

A method, developed to detect low concentrations of virus on vegetables, irrigated with wastewater, was investigated in the field. Celery, spinach, lettuce and tomato crops, grown at an experimental station near Melbourne, Victoria, were spray-irrigated with stored wastewater, which had been seeded with either poliovirus or adenovirus.At specified intervals after irrigation, vegetables were harvested, washed to remove virus and the washings concentrated into a small volume which was inoculated into cell cultures for virus isolation. The method demonstrated rapid inactivation, within 48 h, of poliovirus on crops and low level persistence of this virus for up to 13 days. Adenovirus could not be detected on a lettuce crop as early as 24 h after irrigation. On crops harvested immediately after irrigation and stored at 4°C in a humid atmosphere in the dark, the method was able to demonstrate more gradual inactivation of poliovirus than under field conditions and virus persistence for up to 76 days. Since seeded virus concentrations were similar to those commonly detected in wastewater before storage, results indicate that this is a practical method for assessing viral contamination of vegetable crops spray-irrigated with wastewater.     

Optimal planning of distributed generation with application of multi-objective algorithm including economic,environmental and technical issues with considering uncertainties

This paper proposes a stochastic multi-objective model for integration of distributed generations (DGs) in distribution networks. The proposed model determines the optimal location and size of DGs by optimising different objective functions dependently and simultaneously subject to the operating constraints. If proper sizes of DGs are located in suitable sites and are also managed properly they can improve integrity, reliability and efficiency of the system. Regarding the widespread impact of uncertainties, some strategies must be devised in order to incorporate them well into power system modelling and hence achieve the best possible strategy to be adopted which its characteristics keep closer to reality. The most important uncertainties in network planning are load forecasting and market price errors. The proposed scheme is solved using non-dominated sorting genetic algorithms II, allowing the distribution company (DisCo) to exercise his/her personal preferences. To validate the effectiveness of the proposed scheme, simulations are carried out on a 33-bus distribution network and finally the attained results are discussed.     

确定地下水可开采量的随机风险分析方法

地下水可开采量的确定过程中存在着大量的不确定性因素,而传统的确定性模型在处理不确定性因素方面存在一定的不足,因此,本文在详细分析风险分析的概念及其研究方法的基础上,以辽宁省某地下水水源地为例,用随机风险分析方法—JC法对地下水可开采量进行了确定,并与传统的确定性模型计算结果进行了对比.实例研究表明:JC法充分考虑到数学模型中参数的不确定性因素产生的影响,提高了地下水可开采量计算结果的可靠度,为确定地下水水源地可开采量提供了一种更安全、可靠、可行的方法。     

AN INEXACT TWO-STAGE STOCHASTIC PROGRAMMING MODEL FOR WATER RESOURCES MANAGEMENT UNDER UNCERTAINTY

An inexact two-stage stochastic programming (ITSP) model is proposed for water resources management under uncertainty. The model is a hybrid of inexact optimization and two-stage stochastic programming. It can reflect not only uncertainties expressed as probability distributions but also those being available as intervals. The solution meth od for ITSP is computationally effective, which makes it applicable to practical problems. The ITSP is applied to a hypothetical case study of water resources system operation. The results indicate that reasonable solutions have been obtained. They are further analyzed and interpreted for generating decision alternatives and identifying significant factors that affect the system's performance. The information obtained through these post-optimality analyses can provide useful decision support for water managers.     

Subsurface water quality and quantity from the standpoint of irrigation and livestock

Field studies were undertaken at the Oyo North Agricultural Development Project (ONADEP), Shaki, Nigeria in 1988 and 1989 to evaluate the reliability and quality of subsurface water sources in relation to irrigation and livestock usage. Based on data from 22 water samples, 15 soil types, seasonal consumption of water for 10 major crops and extensive hydrogeological records, it was established that (i) alkalinity and salinity hazards are low, hence the groundwater of the study area is suitable for irrigation, (ii) excessive boron levels might restrict the usage of the groundwater of the study area for livestock, (iii) subsurface water sources, estimated at about 31,000 ML per annum is capable of satisfying only 12% of agricultural and livestock water demand of the study area, and (iv) the area under consideration is not endowed with abundant surface and subsurface water as shown by previous studies.     

洪临灌区渠道防渗及处理措施

因肃州区洪临灌区处于干旱地区的多种农业土壤中,灌区的水渠和农田水分渗漏损失较大,以致大量水分无效消耗且灌溉水利用率不高,也不利于农作物生长。因此提高灌区输水渠道的防渗性和改进灌区灌溉措施,不仅缓解干旱地区水资源不足的问题还可提高灌溉水利用率,针对灌区渠道情况提出一些防渗措施。