Controlled drainage — effects on drain outflow and water quality

A field experimental project was set up in southern Sweden to assess the effects of controlled drainage on hydrology and environment. Controlled drainage makes it possible to vary the drainage intensity with the variation in drainage requirement during season by controlling the height of a riser in the drain outlet and thus to a certain degree control the amount of outflow of solutes via the drainage system. During periods with low drainage demand, the riser in the drain outlet can be raised and the groundwater level in field will rise up to the level of the riser before the discharge takes place. Three plots, each with an area of 0.2 ha (40 m×50 m) were installed on a loamy sand. One plot was drained by conventional subsurface drainage (CD) and two plots were drained by controlled drainage (CWT). The plots contained four lateral drain tubes, at 10 m spacing and placed at 1 m depth. Each plot was isolated by a double layer of plastic sheeting placed in the back-filled trenches to a depth of 1.6 m to prevent lateral leakage and subsurface interactions. Measurements of precipitation, drain outflow and soil and air temperatures were carried out hourly. Groundwater levels were measured and samples of drain outflow were collected twice a month for nitrogen and phosphorous analyses. Mineral nitrogen contents in soil were measured three times a year.Controlled drainage had a significant hydrological and environmental effect during the 2 years of measurement (1996–1998). Compared with CD, the total drain outflow from CWT was 79% less in Year 1 and 94% in Year 2. The total reduction in nitrate losses with CWT corresponded to the reduced outflow rates. Compared with CD, the total amounts of nitrate in drain outflow were 78% less in Year 1 and 94% in Year 2. The highest concentrations of nitrate were measured at the time of the largest outflow rates. The phosphorous losses were 58% less for CWT as compared to the CD values in Year 1 and 85% less in Year 2. The reduction in nitrogen content in the soil profile during the winter season was 60–70% less in CWT than in CD.     

Use of a covariance variogram to investigate influence of subsurface drainage on spatial variability of soil–water properties

Knowledge of the spatial variability of soil–water properties is of primary importance for management of agricultural lands. This study was conducted to examine which spatial structure measure, the semi-variogram or the covariance variogram, is appropriate for inference of the spatial structure and performing interpolation of soil–water properties from sample data sets. Using the appropriate spatial structure measure, the spatial variability of these properties (saturated hydraulic conductivity, water table depth, groundwater salinity, and soil salinity and sodicity) as affected by subsurface drainage is also evaluated. The soil–water properties were sampled before and after the installation of subsurface drainage on a regular square grid of 500 m at 61 locations within 1470 ha in the Nile Delta of Egypt. The results showed that the covariance variogram reveals the character of spatial structure and that it is more appropriate for interpolation than the semi-variogram. Subsurface drainage has highly affected the spatial variability of soil–water properties. On average, the spatial correlation range increased by approximately 29%, whereas the ratio of structural heterogeneity to the total variation (relative structured heterogeneity) was doubled 4 years after drainage installation. Moreover, the nugget effect increased and was present for all soil–water properties with noticeably high values. Uneven spatial distributions were also observed. Further study of long-term spatial variation of soil–water properties as affected by subsurface drainage is suggested.     

Asset Management for Irrigation and Drainage Infrastructure – Principles and Case Study

This paper presents the general principles and functions of asset management for irrigation and drainage infrastructure: Asset planning and creation strategies, operation and maintenance, performance monitoring, accounting and economics and audit and renewal analysis. The various elements of the program are conceptually defined and their application is illustrated with the asset management program (AMP) formulated for the La Khe Irrigation System in Vietnam. It also identifies the role of the AMP within the framework of service oriented management of irrigation and drainage services. An infrastructure and investment profile developed from the asset survey identified the investment requirement over the next 40 years. The analysis of cost of service and revenues shows a shortfall of US£17.00/ha/annum to meet the investment requirement over this period. The asset audit and renewal analysis shows the upgrades of the main system needed to improve the current level of service.     

名利场宠儿 Execs and the city

宝马3系向来是小型行政车型追随者的唯一选择。不过，新款奥迪A3三厢版和奔驰CLA将与宝马3系一起角逐小型行政车市场，其中，奔驰CLA拥有如跑车一般圆润的流线型外观，而奥迪A3则在售价方面占有优势。新款雷克萨斯IS采用油电混动系统，能够输出更大动力，并且二氧化碳排量比其他竞争车型更低。     

International Commission on Irrigation and Drainage-ICID

InternationalCommissiononIrrigationandDrainage-ICID48NyayaMarg;Chanakyapuri;NewDelhi110021,IndiaTel:3016837;30108621Fax:91-11-3015962;E-Mail:icid@sirnetd.ernet.in;Cable:INTCOIRICIDJournal-GuidetoAuthorsIntroductionTheobjectivesoftheinternationalCommission…     

The Information Engineering Institute and the Electromechanical Engineering Institute, Jinhua College of Profession and Technology

JinhuaCollegeofProfessionandTechnologywasfirstfoundedin1994andwasgrantedasoneofthe keystate-levelconstructingcollegesin2003.Itisacomprehensiveandfull-timehighervocationalcollege,boastingwiththesubjectsofengineering,agriculture,medicine,economics,management,literature,pedagogyandarts.Thecollegeconsistsof12subordinateinstitutesofInformationEngineering,ElectromechanicalEngineering,ArchitecturalEngineering,GeneticEngineering,TradeandEconomy,Pedagogy,Medicine,Tourism,Arts,MaterialsandChemica…     

Response of grapevine cv. ‘Tempranillo’ to timing and amount of irrigation: water relations, vine growth, yield and berry and wine composition

The effects of several moderate irrigation regimes on vine water status, yield, and must and wine composition, were investigated during five seasons in a vineyard planted with Vitis vinifera cv. Tempranillo. Treatments consisted of non-irrigated vines and six differentially irrigated treatments with contrasting watering regimes during the pre-veraison and post-veraison periods. There were large differences in yield and grape and wine quality responses to irrigation among seasons, probably as consequence of the different environmental conditions and crop levels. It was, however, clear that vines benefit more of the irrigation supplied in years of high yield levels. Across seasons, yield increased in proportion to the amount of water applied mostly due to the larger berries of irrigated vines, and there was no clear response to the timing of irrigation supplied. In addition, there were no carry over effects due to irrigation on bud fertility. The post-veraison water application was necessary to increase must sugar level and wine alcohol content. However, water restrictions during the pre-veraison period lead to more concentrated berries in terms of total phenolic and anthocyanins. The only noticeable detrimental effect of irrigation, regardless of the timing of its application, on wine composition was an increase in wine pH.     

Can carbon isotope discrimination and ash content predict grain yield and water use efficiency in wheat?

Drought is the main factor affecting crop grain yield. Increasing grain yield under drought and crop water use efficiency (WUE) is essential for enhancing world crop production and food availability. The objective of this study, carried out in India on 20 durum wheat cultivars, under three water regimes (full irrigation, limited irrigation and residual soil moisture) and during two seasons, was to investigate the potential use of plant traits (particularly carbon isotope discrimination, Δ, and ash content, m_a) to predict grain yield and WUE in wheat. WUE components were estimated using a soil water balance model (Budget) allowing comparison of environments in data scarce situations. A highly significant correlation was noted between grain yield and grain Δ across water regimes. However, the associations between grain yield, Δ and m_a were found to depend highly on the water regime and environmental conditions. The association between grain yield and grain Δ was significant under full irrigation in season 1 and under residual soil moisture in season 2. Significant positive correlations were noted in both seasons between grain yield and leaf Δ under residual soil moisture and between grain yield and leaf ash content at anthesis under limited irrigation. A significant correlation was found across environments between grain and leaf Δ and T, the quantity of water transpired during the growth cycle, as estimated by the soil water balance model. T also significantly correlated to grain and leaf m_a. Variation in WUE across environments was driven more by runoff, drainage and soil evaporation than by harvest index and transpiration. The associations between WUE and transpiration, runoff and Δ were negative but not significant. WUE was significantly correlated with leaf and grain m_a at maturity. The study indicates that Δ and m_a can be used as indirect selection criteria for grain yield and suggests that m_a is a good predictor of transpiration, grain yield and WUE across environments. The use of mechanistic models that allows differentiating between cultivars should permit in a next future to analyze the relationships between WUE, Δ and m_a across cultivars and evaluate the possibility to use these traits as predictors of WUE in wheat breeding programs.     

SPRINKMOD – pressure and discharge simulation model for pressurized irrigation systems. 1. Model development and description

A computer model was developed to simulate pressure and flow rate distribution along pipes and laterals of pressurized irrigation systems in operation. The software runs in a Windows environment and is capable of simulating irrigation systems having multiple pump stations combined in series and/or in parallel, booster pump stations, parallel pipes and looping pipes. Hand-move, wheel line and center pivot laterals with pressure regulators, one or two drop pipes per outlet and booster pump can be simulated. Leakage can be included in the main pipe network or along the laterals. Lateral inlet pressure can be set to an upper limit to simulate valve closure. Practically any type of nozzle and pump can be simulated since cubic spline functions are used to interpolate values from head-flow rate sets of data. To accomplish these capabilities, algorithms were developed and adapted to convert laterals into a set of head-flow rate data so that a simplified algorithm could be adapted to solve the entire pipe network. A user-friendly interface was designed to allow data for pumps, nozzle and pressure regulators to be interactively entered, edited and analyzed prior to the simulation run. The layout of the irrigation system can be drawn on screen using the mouse. Data can be independently entered and edited for each irrigation system component already drawn in the screen, at any time and in any order. Data for the entire irrigation system are verified at many levels before the simulation is run, to make the model less susceptible to crash. The model proved to be a practical tool for upgrading and designing pressurized irrigation systems. Received: 20 November 1997     

Water and nitrogen transport characte-ristics of single-line interference infiltra-tion under film hole irrigation with muddy water and fertilizer

Based on the experimental data, this study investigated the effect of sand content of muddy water on water and nitrogen transport characteristics of the single-line interference infiltration under film hole irrigation with muddy water and fertilizer. The relationship between the single-line interference infiltration parameters and the sand content, and the wetting front movement distances, and the sand content are all established. The model of the cumulative infiltration volume of per unit film pore area, the vertical and horizontal wetting front movement distance of the free surface, and the wetting front movement distance of the interference center with sand content and infiltration time are proposed. Reveal the law of the change of soil water content and the distribution of NO^-₃-N content based on diffe-rent muddy water sand content. The results indicate that at the same infiltration time, as the muddy water sand content increases, the cumulative infiltration volume per unit pore area decreases. The infiltration index of the free infiltration and the single-line interference vary little when the sand content increase, mainly are around 0.64 and 0.58. The relationship between infiltration parameters a, b and the sand content is linear function. At the same location, the more the sand content, the smaller the wetting front movement distance in free surface and the single-line interference surface, the less the NO^-₃-N content.     

Social capital and farming at the rural–urban interface: the importance of nonfarmer and farmer relations

Because of growth and development in agricultural areas at the rural–urban interface, a variety of farmer adaptations have been identified. While exiting from farming or entrepreneurial adaptations that tap urban markets are frequently identified responses, farmers might also attempt to develop social capital, or neighborly relations, with nonfarm neighbors to mitigate social constraints created by nonfarmer concerns at the rural–urban interface. In a case study of an agricultural region within a large metropolitan area, this research reports data from a survey of farm and nonfarm residents (N=620). The analysis operationalizes the concept of social capital, nonfarmer trust of farmers and frequency of nonfarmer interaction with farmers, to determine whether these social relations have a discernable impact on nonfarmer support or tolerance of agriculture. Results reveal a relationship, indicating that support and tolerance of agriculture is stronger when nonfarmers report the existence of social capital with farmers. These findings have implications for farm operator adaptations as well as community capacity to preserve or develop local agriculture.     

Energy accounting and well-being — examining UK organic and conventional farming systems through a human energy perspective

This paper quantifies and compares the energy efficiencies of conventional and organic farming systems in the UK from a human energy perspective. To date, studies comparing these two systems have neglected rudimentary questions regarding the effort and energy expenditure of farmers, instead devoting attention to consumer health and selected environmental issues such as global warming and recent energy crises. The need to focus on the human energy problem is seen as fundamental in this paper as it concerns not just the balance of calorific expenditure and consumption but also the possible negative health affects associated with high levels of energy and effort expenditure. Assessment of human energy expenditures and effort, and their health effects is relatively under-developed; consequently this paper uses a pilot study to explore methodology on which future study and theory could be based. The method developed draws on three plausible models for assessing human energy and effort expenditure: the nutritional, physiological and ergonomic. The case study builds annual and daily profiles of energy and effort expenditure of two farmers using annual labour profiles and task specific energy expenditure and intensity derived from physical measurements. Although the scope of the experiment is limited, making inferences about each system is difficult, the results reveal clear differences in the annual energy and effort expenditures of the two farmers. Over a typical year the organic farmer experiences far more physical stress. Despite being more efficient in terms of overall energy, the organic farm is less efficient in terms of human energy, and the net energetic returns combined with effort intensity bring into question the health implications of organic livelihoods both in the short and long term.     

Brief Introduction to Agricultural and Biosystems Engineering Discipline,College of Biosystems Engineering and Food Science Zhejiang University

Agricultural and Biosystems Engineering Discipline of Zhejiang University was a keydiscipline of the National “985”Program.This discipline currently has52 faculty members,including 1 Academician of Chinese Academy of Engineering,1 6professors,and 1 3 Ph.D.student supervisors. Our discipline has many well-equipped labs,including a Key Open ResearchL ab of Agriculture Ministry of China,and some experimental bases forteaching and researching.In the recent3 years,over1 3 0 research proje…     

Good governance and IWRM—a legal perspective

Developing a methodology for the measurement of governance in the context of water management requires a clear understanding of what is meant by (good) governance, and what is meant by IWRM—terms which are often, but incorrectly, used almost interchangeably. This paper sets out the foundations developed for the STRIVER project upon which an assessment of governance could be made. It identifies the key principles of good governance as being accountability, participation and transparency, and seeks to elucidate the relationship between good governance and IWRM, especially in relation to the specific role of law. The paper concludes that while the two are not mutually exclusive, the access points between them appear to concentrate around issues relating to equity, the protection of “silent” interests and the importance of governance in facilitating feedback mechanisms.     

Fate and risks of potentially toxic elements in wastewater-fed food production systems—the examples of Cambodia and Vietnam

Non-treated wastewater is used for irrigation of aquatic food production systems in the peri-urban areas of the major cities in Southeast Asia. This paper complement the knowledge on agricultural soil-based crops irrigated with low quality water, by reviewing the research findings on the wastewater-fed aquatic productions with special focus on heavy metals and other potentially toxic elements (PTEs) in the production systems of Hanoi in Vietnam and Phnom Penh in Cambodia. In Hanoi, sediments in the wastewater exposed rivers of Hanoi were reported to be polluted with PTEs, in particular with Cadmium (Cd). The river sediment had a high retention capacity for PTEs which seems to prevent the transport of PTEs to the wastewater-fed production systems. In Phnom Penh, domestic and industrial wastewater is pumped into the Cheung Ek Lake located south of the city. A major part of the water spinach (Ipomoea aquatica Forssk.) consumed in the city is produced in the lake. The concentrations of some PTEs were elevated at the wastewater inlets to the lake compared to concentrations at the lake outlet and at the control site. Water spinach is by far the major vegetable produced in the wastewater-fed systems in Hanoi and Phnom Penh, but did only contain PTEs in concentrations within or slightly above the concentration range observed for water spinach grown in agricultural soil not exposed to wastewater. PTE concentration in fish grown in wastewater-fed systems in Hanoi and Phnom were low. However, mean PTE concentrations in liver and skin of some fish were high. Consumption of muscle tissue from fish produced in wastewater-fed systems in Hanoi and Phnom Penh resulted in an estimated intake of PTEs amounting to less than 9% of the tolerable intake. It was concluded, that the PTE concentrations in fish and water spinach from Hanoi and Cheung Ek Lake in Phnom Penh constituted low food safety risks for consumers.