Crop and irrigation management strategies for saline-sodic soils and waters aimed at environmentally sustainable agriculture

Irrigation has long played a key role in feeding the expanding world population and is expected to play a still greater role in the future. As supplies of good-quality irrigation water are expected to decrease in several regions due to increased municipal-industrial-agricultural competition, available freshwater supplies need to be used more efficiently. In addition, reliance on the use and reuse of saline and/or sodic drainage waters, generated by irrigated agriculture, seems inevitable for irrigation. The same applies to salt-affected soils, which occupy more than 20% of the irrigated lands, and warrant attention for efficient, inexpensive and environmentally acceptable management. Technologically and from a management perspective, a couple of strategies have shown the potential to improve crop production under irrigated agriculture while minimizing the adverse environmental impacts. The first strategy, vegetative bioremediation--a plant-assisted reclamation approach--relies on growing appropriate plant species that can tolerate ambient soil salinity and sodicity levels during reclamation of salt-affected soils. A variety of plant species of agricultural significance have been found to be effective in sustainable reclamation of calcareous and moderately sodic and saline-sodic soils. The second strategy fosters dedicating soils to crop production systems where saline and/or sodic waters predominate and their disposal options are limited. Production systems based on salt-tolerant plant species using drainage waters may be sustainable with the potential of transforming such waters from an environmental burden into an economic asset. Such a strategy would encourage the disposal of drainage waters within the irrigated regions where they are generated rather than exporting these waters to other regions via discharge into main irrigation canals, local streams, or rivers. Being economically and environmentally sustainable, these strategies could be the key to future agricultural and economic growth and social wealth in regions where salt-affected soils exist and/or where saline-sodic drainage waters are generated.     

Use of in-stream reservoirs to reduce bacterial contamination of rural watersheds

An investigation into bacterial water quality problems was conducted on an interconnected stream and irrigation system within the Oldman River Basin of southern Alberta, Canada. Levels of indicator bacteria, including fecal coliforms, generic Escherichia coli and fecal streptococci, were repeatedly measured in streams and irrigation return canals of this river basin during the summer of 2001. Bacterial-loading segments of the irrigation/stream system were identified through a comparison of indicator bacteria levels in pairs of upstream and downstream sites. Mann-Whitney U-tests indicated that reservoirs significantly reduced bacterial counts. A temporal comparison of E. coli counts and river discharges suggested that these indicator bacteria do not originate from within in-stream sediments. Site-specific as well as cumulative inputs from a variety of non-point sources are likely to be responsible for the high downstream levels of indicator bacteria in this water system. The use of management practices such as in-stream reservoirs may significantly reduce contamination, and increase the quality of limited rural water supplies to allow their reuse and safe discharge into downstream water sources. The identification of bacteria-loading river/canal segments could also be used to prioritize restoration projects.     

Assessing farmers' practices on disposal of pesticide waste after use

Common practices of farmers on disposal of pesticide waste after use were surveyed in five regions of the rural area of Pieria in northern Greece using a structured questionnaire administered via personal interviews. Concerning leftover spray solutions, most farmers reported that they normally re-spray the treated field area until the spraying tank is empty (54.9%) or they apply the leftover spray solutions to another crop listed on the product label (30.2%). A minority of the farmers (4.3%) mentioned that they often release the leftover spray solutions near or into irrigation canals and streams. As regards rinsates generated from washing the application equipment, most farmers reported that they release the rinsates over a non-cropped area (45.7%) or they drop the rinsates near or into irrigation canals and streams (40.7%). Moreover, a great proportion of the farmers stated that they dump the empty containers by the field (30.2%) or they throw them near or into irrigation canals and streams (33.3%). Burning the empty containers in open fire (17.9%) or throwing the empty containers in common waste places (11.1%) was also reported. Several farmers stated that they continue to use old pesticides for spraying (35.8%). Training programs which raise awareness of farmers of the potential hazards of pesticide use and particularly of the proper management of waste products, recycling programs and collection systems for unwanted agricultural chemicals to prevent inappropriate waste disposal, as well as improving packaging of pesticides to minimize waste production are essential for promoting safety during all phases of pesticide handling.     

Real-Time Water Allocation for Irrigation

Throughout the world the importance of water management is becoming more important as the demand for water increases. As one of the major uses of water, irrigation could benefit from improved management practices. The establishment of a Water Operations Centre in Indonesia has seen the development of a real-time water-allocation model for a complex irrigation system covering 60 000 ha. The model uses linear programming (an optimization technique) to determine the best way in which to allocate limited water supplies while keeping crop yield losses to a minimum.     

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。     

Agriculture: Sustainable Business – Sustainable Environment?

Irrigation is a small but important part of UK agriculture, accounting for about 150 000 ha of land and 160 000 Ml of water in a 'dry'year. By the year 2021, the irrigated area is predicted to increase by 14% and the volume applied by 50%. Irrigation is of significant economic importance to (a) farmers, (b) growers, (c) the food industry – improving crop yields, quality, consistency and reliability.
The environmental impacts of irrigation on river flows and wetland biodiversity are now receiving more attention. Irrigators are given advice on environmental impacts, voluntary agreements are secured between groups of irrigators and the Environment Agency, and on-farm reservoirs are constructed to reduce summer abstraction and provide more secure and flexible supplies. Better long-term planning and short-term management are essential.     

The use of propeller turbines in low head stand alone micro hydro electric power generation units

The mountainous regions of developing countries offer a great potential for small scale hydroelectric schemes, running as stand alone units. Such schemes with power output less than 100kW are usually referred to as micro-hydro power generation units. For low—head sites (available head less than 10 m), there is a vast number of suitable sites in countries with less mountainous areas and high rainfall, or extensive irrigation canals.

The present paper introduces the design features of an appropriate propeller turbine design. The turbine will be directly coupled to an induction generator. The design requirements, materials selection and manufacturing processes are analysed with respect to experiences from pilot projects within the UK and abroad.     

Probable risk estimation due to reservoir induced seismicity at Jamrani dam Project,Kumaon Himalaya,India

A lake of about 4.5 sq. km. spread having 208 millions cubic meter storage capacity is proposed to be created in outer Himalaya for meeting irrigation, industrial and domestic supplies, downstream of 130 m high Jamrani dam. The bedrock around the lake consists of alternate bands of sandstone, clayshale and siltstone of siwalik Formations, (Middle Miocene to Pliocene) and thrust mass of Amritpur granite. The tectonic plane (Main Boundary fault) lies about 3.5 km upstream of the dam. The problem of Reservoir Induced Seismicity (RIS) though complex and unpredictable has been studied the world over at several major dam projects which provide some information on the factors responsible for RIS such as (i) geo-tectonic, setting (ii) pore-water pressure (iii) background seismicity and (iv) reservoir water load. Any one or the combination of these factors play an important role in inducing, earthquakes. The subject of RIS has been discussed in the light of the analysis of the seismic risk related to Jamrani reservoir in its geo-tectonic setting.     

Subterranean Landscape: The Far-Reaching Influence of the Underground Qanat Network in Ancient and Present-Day Iran

Persia's ancient civilisation was constructed on qanats - an extensive subterranean network of canals - that supplied vital water for drinking and irrigation. Reza Daneshmir and Catherine Spiridonoff of Fluid Motion Architects describe how an on-site encounter with qanats in Tehran helped to unleash not only a new understanding of historic urban development and its social fabric, which evolved around these ancient water channels, but also led to new thinking about the current potential of the qanats and their possibilities for greening the capital.     

Colonial Irrigation: Myths of Emptiness

Colonial efforts to develop irrigation in African colonies aimed to improve the colonies' productive capacity. The resulting systems, including Gezira (British Sudan), Office du Niger (French Sudan) and the French systems in Northern Africa, have many characteristics of an imposed factory-based production regime. A factory resemblance is reflected in the mathematical layout of the systems when possible: canals are straight and plots are square. This approach coincides with the general European opinion that Africa had no history; Africa (with the exception of Egypt) was perceived as an empty continent. In the African colonies, economic opportunities were obviously an important element of the discourse. It was ideologies of creating new social and geographical landscapes, however, bringing order in the wildness by filling the empty African landscape with modern irrigation facilities, that were dominating the colonial irrigation discourses and practices in African colonies.     

Heavy metal contamination of water, soil and produce within riverine communities of the Río Pilcomayo basin, Bolivia

The Río Pilcomayo heads on the Cerro Rico de Potosí precious metal-polymetallic tin deposits of Southern Bolivia. Mining of the Potosí deposits began in 1545 and has led to the severe contamination of the Pilcomayo's water and sediments for at least 200 km downstream of the mines. This investigation addresses the potential human health affects of metal and As contamination on four communities located along the upper Río Pilcomayo by examining the potential significance of human exposure pathways associated with soils, crops and water (including river, irrigation and drinking water supplies). The most significantly contaminated agricultural soils occur upstream at Mondragón where Cd, Pb and Zn concentrations exceed recommended guideline values for agricultural use. Further downstream the degree of contamination decreases, and metal concentrations are below Dutch, German and Canadian guideline values. Metal and As concentrations in agricultural products from the four communities were generally below existing guidelines for heavy metal content in commercially-sold vegetables. Thus, the consumption of contaminated produce does not appear to represent a significant exposure pathway. A possible exception is Pb in carrots, lettuce and beetroots from Sotomayor and Tuero Chico; 37% and 55% of the samples, respectively, exceeded recommended guidelines. Most communities obtain drinking water from sources other than the Río Pilcomayo. In general, dissolved concentrations of metals and As in drinking water from the four studied communities are below the WHO guideline values with the exception of Sb, which was high at Tasapampa. The inadvertent ingestion of contaminated water from irrigation canals and the Río Pilcomayo represents a potential exposure pathway, but its significance is thought to be minimal. Given the degree of soil contamination in the area, perhaps the most significant exposure pathway is the ingestion of contaminated soil particles, particularly particles attached to, and consumed with vegetables. The risks associated with this pathway can be reduced by thoroughly washing or peeling the vegetables prior to consumption. Other exposure pathways that are currently under investigation include the consumption of contaminated meat from livestock and poultry, which drink polluted waters and the ingestion of contaminated wind-blown dust.     

USE OF GROUNDWATER AGE INDICATORS IN RISK ASSESSMENT TO AID WATER SUPPLY OPERATIONAL PLANNING

Groundwater residence-time survey results on 21 public water supplies in the chalk aquifer in southern England are compared with a previous Cryptosporidium risk assessment which was carried out on the same supplies for regulatory-compliance purposes in 1999. The results indicate that residence-time indicators could provide useful corroborative evidence for rapid recharge hazard - not only in those settings already identified by microbiological surveillance, but also in the more difficult-to-identify situation where potential rapid pathways have been identified but the bacteriological indicators are negative or ambiguous. However, groundwater-mixing processes under pumping conditions are complex, especially in the chalk, and will always require interpretation informed by an understanding of the local hydrogeological and operational setting.     

Effect of irrigation on a deep aquifer: a case study from the semi-arid Harran Plain,GAP Project,Turkey

Inappropriate irrigation practices are responsible for the deterioration of groundwater quality in a great number of developing countries, particularly in semi-arid and arid regions. The study was undertaken to determine the variation in groundwater quality of a deep aquifer after surface irrigation was started in the semi-arid Harran Plain, southeast Turkey. Physical and chemical parameters of the groundwater, including pH, temperature, electrical conductivity, sodium, potassium, calcium, magnesium, chloride, bicarbonate, sulphate and nitrate, were determined on a monthly basis from November 2008 to July 2009. The quality of the deep aquifer was assessed hydrochemically in order to determine its suitability for human consumption and agricultural purposes. With the exception of two wells, the measured and analyzed parameters in all the groundwater samples were below the internationally accepted maximum concentrations for human consumption and for agricultural purposes. The study identified a local contamination as a consequence of excess irrigation, high evaporation rates and drainage. It is hoped that the results will assist planners in the proper design and control of irrigation schemes to avoid further deterioration of these important aquifers.     

区域水系影响下的明代宁夏镇城园林特征与风格研究

宁夏镇城(明代银川市旧称)位于古老的引黄灌区宁夏平原的中部,渠湖串联的区域水系为造园带来便利.聚焦于此,通过史料考证和位置复原,再现了镇城主要园林的空间分布,并系统研究其造园特征与园林风格.研究表明,宁夏镇城园林具有湖渠立园、环水塑景、水系多样与意境悠远的特征;园林风格集地域风景、贵族、文人和生产特质于一体,这与历史环...     

Genetic diversity of Escherichia coli isolates in irrigation water and associated sediments: implications for source tracking

Identifying the sources of fecal contaminants in surface water bodies such as rivers and lakes is of significant importance for environmental quality, food safety and regulatory purposes. Current DNA library-based source tracking approaches rely on the comparison of the genetic relatedness among the fecal contaminants. The objective of this study was to determine the genetic relatedness of Escherichia coli isolated from irrigation water and associated sediments using pulse field gel electrophoresis (PFGE) and to evaluate the genetic stability of the E. coli PFGE patterns. The isolates were obtained over a 4-month period from specific locations within irrigation canals and sediments associated with the Rio Grande River along the Texas-Mexico border. Fifty E. coli isolates were genotyped using PFGE. Different E. coli genotypes were identified among samples collected in 11 different locations. Some isolates obtained over successive months showed similar genotypic patterns. In the laboratory experiment, the PFGE pattern of one E. coli strain changed during survival in irrigation water. The genetic relatedness of this strain changed from >95% to <83% over 8-week survival. These results imply that PFGE is of such extreme resolution that it may be a challenging task to rely solely on a PFGE-based source tracking DNA fingerprint library for large watersheds.     

干旱区城市绿地系统“林网化”与“水网化”设计——以新疆生产建设兵团农三师河东新镇绿地系统规划为例

我国西北干旱区由于其特殊的地理位置与气候特点,限制了绿地的成片建设,许多城市目前未形成功能完整的绿地系统。本文提出将绿洲地区用于灌溉的渠网纳入城市绿地系统中,强调林网水网一体化设计,并以新疆建设兵团农三师河东新镇绿地系统规划为例做了较为详细的介绍。     

A review of ET measurement techniques for estimating the water requirements of urban landscape vegetation

Increasing urbanisation combined with population growth places greater demands on dwindling water supplies. This is especially the case in arid and semi-arid areas like Australia, which is known as the driest inhabited continent on earth. Sustainable irrigation management necessitates better understanding of water requirements in order to decrease environmental risks and increase water use efficiency. Although the water requirements of agricultural crops are well established in field and laboratory studies, little research has been conducted to investigate the water requirements of urban green spaces. In addition, most previous research investigations have focused on the water requirements of turf grasses and not on other landscape plant species. Landscape plants can include various species of trees, shrubs and turf grasses with different planting densities and microclimates. Such complicated environments make measuring the water requirements of urban landscapes difficult.

This paper reviews previous studies and techniques for measuring the water requirements of urban landscapes and describes how optimum irrigation management strategies for urban landscape vegetation can assist in better water conservation, improved landscape quality and reduced water costs. The authors conclude that WUCOLS is a practical approach that can provide an initial estimate of urban landscape water demand but ideally this should be further refined based on the health and aesthetic condition of the urban vegetation. The authors recommend calibration of the WUCOLS estimates with an in-situ method such as a soil water balance.     

Geosynthetics for waterways and flood protection structures – Controlling the interaction of water and soil

The interaction of water and soil has been both a blessing and a curse in all times within living memory. Water is the origin of life but is also threatening life when appearing unboundedly. Therefore mankind has always worked hard to benefit from water resources on one hand and to deal with the threat of flooding on the other hand. For both, to protect the land and to allow for beneficial uses like irrigation or navigation, often special measures are necessary to keep the water within certain bounds. Structures to achieve a permanently stable situation like irrigation and navigational canals, river training or flood protection measures need suitable material, carefully thought out design and accurate execution. Often a decision has to be made among competitive approaches to optimize such structures. In many cases, geosynthetics can support or improve the functionality and sometimes only with geosynthetics the desired result can be achieved.     

Bureau of reclamation experiences with PVC seams

The Bureau of Reclamation has been using polyvinyl chloride (PVC) plastic in its buried membrane canal lining work for over 20 years. Results of tests conducted on samples of inservice linings indicate that the factory-fabricated seams retain excellent shear and peel strength properties with no apparent signs of deterioration. The practice of using a 1-m overlap unbonded PVC field seam proven has adequate for most irrigation canal lining applications, but would not be suitable for applications requiring 100% seepage control. Results of laboratory investigations conducted in conjunction with a study on the underwater lining of operating canals with PVC indicate that an adhesive formulated for the repair of vinyl swimming pool liners can be used to make underwater PVC field seams. Results of these investigations also indicate that field seams made in the dry can achieve enough early peel and shear strength development (within 15 min) for placement underwater.     

基于灰色聚类法的水利枢纽灌区PPP 项目风险评价研究

基于水利枢纽灌区 PPP 项目的一般特点及其特殊性,提出不同责任主体的 6 个风险一级指标、25 个风险二级指标的风险评价体系,通过 AHP 法确定各级风险指标权重值,运用灰色聚类法中的三角白化权函数的评估方法,将分散的风险评价信息处理成不同灰类度的评价量,从而得出项目的综合风险等级。结合 B 灌区二期工程项目进行应用分析,为我国水利枢纽灌区 PPP 项目规避风险、降低损失提供切实可行的理论指导依据。