Changes in hydraulic performance and comparative costs of lining and desilting of secondary canals in Punjab,Pakistan

Observations on the hydraulic changes of lining of secondary canals in Punjab, Pakistan show that performance improvement objectives are not always achieved. If lining is justified on the basis of water savings through reduced seepage losses, then tail end areas should receive improved water deliveries. Observations in two distributary canals following lining do not demonstrate significant improvements in tail end conditions. Justification of lining on the basis of more stable water conditions is also hard to identify; reduction in the variability of discharges was not observed.Financial analysis of a recent canal lining experience in Punjab indicates that water savings would have to be unrealistically high, and sustained for long periods, if the initial capital cost is to be repaid through improved water conveyance efficiency. Furthermore, the hydraulic improvements achieved through alternative interventions appear to strengthen the argument that lining can be justified only under special conditions, rather than adopted as a wholesale approach to solving water distribution problems. Whatever the intervention, management control must be strengthened; lining is not a substitute for effective canal operational and maintenance inputs.     

Performance assessment of irrigation water management in old lands of the Nile delta of Egypt

This paper provides the methodology and results of a cross-scale diagnostic performance assessment program of the irrigation water management in the old lands of the Nile Delta of Egypt. The analysis was done at three levels; main canal level, branch canals level and on-farm level of the Meet Yazid command (82,740 ha) for the year 2008?C2009 to highlight areas for improvement. At the main canal level the annual average percentage of irrigation water returning to drains and groundwater was 53% of the total water supplied. Since Meet Yazid lies at tail end of the delta, and there is groundwater salinity, opportunities for reuse are increasingly limited moving north to Lake Burullus. This would indicate opportunities for real water savings. The results of monthly relative water supply of the main canal indicated mismatch between demand and supply especially during the winter months, and when supply is low farmers do reuse drainage or groundwater. Also, the assessment of the three branch canals showed non-uniformity of water distribution and mismatch between demand and supply even when comparing improved and non-improved canals. At the on-farm level in paddy fields, the amount of irrigation flows to drains and saline sinks varied from 0.46 to 0.71 of inflow. In spite of these values of non-uniformity and low depleted fraction, the relative evapotranspiration (ratio of actual to potential) evaporation was uniformly high, indicating most crops of most farmers were not water stressed, which is also confirmed by the high yield values. The average values of productivity per unit water depleted by ET_act were 1.04 and 1.05 kg/m³ for rice and wheat fields, respectively, with yields of rice and wheat at 8 and 6 t per ha respectively. On farm and tertiary improvements alone will not yield real water savings, as excess water in the main canal and drains will continue to flow out of the system. Rather the focus should first be on supplies to the main canal, accompanied by more precise on farm and water delivery practices at branch and tertiary levels, and ensuring that environmental flows are met. There is an added advantage of focusing on this tail end region of Egypt that this response would lessen vulnerability to reuse of polluted and saline water.     

Using a hydro-dynamic flow model to plan maintenance activities and improve irrigation water distribution: application to the Fordwah distributary in Punjab, Pakistan

In secondary canals in Pakistans Punjab, the waterdistribution depends on the hydraulic characteristicsof channels, cross-structures and tertiary outlets.Maintenance of channels and structures plays a crucialrole in upholding equitable distribution of water tothe tertiary units. In the past, maintenance has beenundertaken by irrigation managers based on experienceand observations. In the present study a hydro-dynamicmodel (SIC – Simulation of Irrigation Canals) is usedto assess a priori the impact of maintenance measureson water distribution. Maintenance measures can thusbe selected that remove existing bottlenecks in thewater distribution in the most cost-effective way. The methodology is applied to a secondary canal insouth-east Punjab. The simulation results show thatthe main cause of present inequity in waterdistribution are deviations in dimensions of tertiaryoutlets, which, if restored, would make the mosteffective contribution to improve the waterdistribution. Maintenance of the channel is necessaryif its capacity diminishes.     

Irrigation in the Jordan Valley: Are water pricing policies overly optimistic?

Water is very scarce in the Hashemite Kingdom of Jordan. The development of both public irrigation in the Jordan Valley and private groundwater schemes in the highlands has diverted a large share of the country's water resources to agriculture. Many policy instruments have been used in the last 10 years to reallocate water to nonagricultural uses and encourage improvements in efficiency throughout the water sector. Demand management has been emphasized, with water pricing policies expected to instill conservation and motivate a shift toward higher-value crops. We examine the rationale for, and potential and current impact of, pricing policies in the Jordan Valley.We describe the likelihood of success of such policies in terms of operation and maintenance cost recovery, water savings and improved economic efficiency, and we explore some of the alternatives available for meeting these objectives. We show that while operation and maintenance (O&M) costs can be recovered higher water prices have limited potential for achieving gains in irrigation efficiency. The current system of quotas, the lack of storage, and technical difficulties experienced in the pressurized networks indicate that little water can be saved. More substantial increases in water prices can be expected to raise overall economic efficiency by motivating farmers to intensify cultivation, adopt higher-value crops, improve technology, or rent out their land to investors. Yet such strategies are constrained by lack of capital and credit, and pervasive risk, notably regarding marketing. Pricing policies, thus, are best implemented together with positive incentives that reduce capital and risk constraints, and offer attractive cropping alternatives or exit options with compensation.     

面向节水型产业结构的黑龙江省行业用水及经济特征分析

在有限的水资源条件下,合理分配水资源,提高用水效率及水的经济效益,已经成为目前的热点问题之一。以2010年投入产出表为数据基础,计算黑龙江省的用水、耗水及污染系数、各产业的影响力、感应力系数、生产诱发系数,进行用水、耗水效益和污染程度分析判断,并进行各产业的经济特征分析。结果表明：（1）农业用水成本最大,污染大,最不经济,出口对农业影响最大;（2）高用水行业主要集中在以资源加工为主的工业内部,高耗水行业只要集中在第二产业的部分制造业,高污染行业主要集中在以制造业为主的工业,投资对第二产业影响最大;（3）黑龙江省第三产业均属于一般用水行业和一般耗水行业,出除了住宿和餐饮业外其他服务业均属于一般污染行业,第三产业用水最经济,污染少,为促进第三产业的发展,应首先提高对第三产业的消费,其次加大对第三产业的投资和出口。     

Assessment of water delivery efficiency in irrigation canals using performance indicators

Agricultural water is delivered by open irrigation canals in system of reservoirs with a widespread distribution in South Korea. Traditional irrigation management problems include water distribution systems with less capacity than the peak demand, irregular delivery rates, and low irrigation efficiency and uniformity. It is necessary to strategically compare the estimated irrigation demands with the actual water supplies for decision making in order to maintain the water supply according to the demand. Accurate measurement and monitoring of water distribution systems is essential in order to solve the problems of water efficiency and availability. Auto water level gauges installed at the head and tail sections of each irrigation canal in the Dongjin River were used to measure the discharge during irrigation periods. In this study, we introduced an approach to assess the water delivery performance indicators of the open irrigation canals, which is essential for identifying the key issues for water management improvement. The irrigation efficiencies according to the water delivery performance indicators were measured with an automatic water gauge in the irrigation canals and were calculated from the spatial and temporal distribution of the water supply for the lack of planning in water delivery. The calculated performance indicators are useful to understand the irrigator behavior and general irrigation trends. Analysis of the results yielded insights into possible improvement methods in order to develop water management policies that enable irrigation planners to improve the temporal uniformity and equity in the water distribution.     

Volumetric water control in a large-scale open canal irrigation system with many smallholders: The case of Chancay-Lambayeque in Peru

Volumetric water control (VWC) is widely seen as a means to increase productivity through flexible scheduling and user incentives to apply just enough water. However, the technical and social requirements for VWC are poorly understood. Also, many experts assert that VWC in large-scale open canals with many smallholders is not feasible. This article debates the practice of VWC, drawing on field studies in the arid North Coast of Peru. Here the large-scale Chancay-Lambayeque irrigation system achieved high allocation, distribution and financial performance with on demand delivery to some 22,000 smallholdings, under a VWC approach, with full cost recovery for operation and maintenance. This study shows there are options to promote VWC if its different elements - volumetric allocation, distribution, metering and pricing - are planned together.     

Effects of improved field practice on crop yield,water use and profitability of irrigation in Central Chile

Summary The economic impact of improved irrigation practice was studied for a number of years in a research project carried out in Central Chile on commercial fields of eleven orchard, field, vegetable and forage crops. The cost of implementing improved irrigation practice specific to a given soil-climate and crop combination, and the benefits obtained through that technology were evaluated with respect to yield increases and savings in water and crop production costs.Semi-permanent irrigation plots were established in different locations in the Central Zone of Chile (Fig. 1). At each site, the field crops were grown in crop rotations for a number of years. Several methods of irrigation were tested, using different frequencies and depths of water application.Crop yields on plots with improved irrigation practice averaged 25% more than on plots on which irrigation was applied, according to traditional farmer practice. A significant increase in consumptive water use by the crop was found with improved irrigation practice, but the total water applied during the growing season was about half of the volume applied in traditional irrigation practice.The results suggest that in developing countries with a comparatively extensive irrigation tradition, little sophistication is needed to improve irrigation practice and obtain a significant economic impact on crop production.     

WaDI (water delivery for irrigation): A simulation tool to address strategic interaction of water demand and supply in irrigation schemes

The WaDI (water delivery for irrigation) model deals with the relations between the collective water supply and the demand within irrigated schemes. It is based on a separate modelling of the water supply and demand, including (i) a simplified representation of the hydraulic structure, characteristics and organizational parameters of the scheme, (ii) an assessment of the water demand of farms based on their total irrigated area, cropping pattern and irrigation practices, (iii) a farm typology, (iv) a confrontation between water demand and supply at each node of the scheme from pumping plants to tertiary canals, and (v) calculation of response factors between supply and demand during the peak demand period. “What-if” scenarios are simulated in order to enhance the stakeholders’ capacity to plan strategic decisions such as water delivery allocation rules or infrastructure investments. WaDI was implemented on two Brazilian schemes. It allowed broadening the stakeholders’ limited representation of collective water supply and demand into a more comprehensive understanding of these relations. The approach however showed some limits, along with the difficulty of assessing the real impact on the stakeholders’ capacity for strategic planning.     

The challenges of wastewater irrigation in developing countries

The volume of wastewater generated by domestic, industrial and commercial sources has increased with population, urbanization, improved living conditions, and economic development. The productive use of wastewater has also increased, as millions of small-scale farmers in urban and peri-urban areas of developing countries depend on wastewater or wastewater polluted water sources to irrigate high-value edible crops for urban markets, often as they have no alternative sources of irrigation water. Undesirable constituents in wastewater can harm human health and the environment. Hence, wastewater irrigation is an issue of concern to public agencies responsible for maintaining public health and environmental quality. For diverse reasons, many developing countries are still unable to implement comprehensive wastewater treatment programs. Therefore in the near term, risk management and interim solutions are needed to prevent adverse impacts from wastewater irrigation. A combination of source control, and farm-level and post-harvest measures can be used to protect farm workers and consumers. The WHO guidelines revised in 2006 for wastewater use suggest measures beyond the traditional recommendations of producing only industrial or non-edible crops, as in many situations it is impossible to enforce a change in the current cash crop pattern, or provide alternative vegetable supply to urban markets.There are several opportunities for improving wastewater management via improved policies, institutional dialogues and financial mechanisms, which would reduce the risks in agriculture. Effluent standards combined with incentives or enforcement can motivate improvements in water management by household and industrial sectors discharging wastewater from point sources. Segregation of chemical pollutants from urban wastewater facilitates treatment and reduces risk. Strengthening institutional capacity and establishing links between water delivery and sanitation sectors through inter-institutional coordination leads to more efficient management of wastewater and risk reduction.     

The Viejo Retamo secondary canal

The intended operation of the Rio Tunuyan irrigation scheme in the province of Mendoza, Argentina, is to divide flow proportionately over the entire area in accordance with registered water-rights. The main division of flow is by regulators at the heads of the lateral canals, which serve areas of appr. 15,000 ha. Taking the sub-lateral or secondary canal Viejo Retamo as an example, this paper discusses the flow division downstream of these regulators. The operation of the canal is evaluated with two performance indicators:

-the ratio of volume of water intended to be supplied to the tertiary units over the volume of water actually supplied, and

-the misallocation of water in volume.

In the Rio Tunuyan scheme, there is also a relation between the evapotranspiration of crops and the groundwater level: if less than 60% of the supplied canal water evapotranspires, the groundwater level rises.     

渡槽式装配U形渠断面设计及结构计算研究

针对我国田间灌溉渠道的定型化设计,参考小型U形渡槽结构的设计方法,结合渠道的承插式连接设计,设计了UD40、UD50、UD60、UD90系列渡槽式装配U形渠。然后研究了渡槽式装配U形渠的结构计算方法,并分别运用梁理论法和有限元分析法对UD60、UD90的断面设计进行了结构尺寸校核。结果表明,承插式连接方式很好地改进了渡槽式装配U形渠的端部构造,提高了渠道接缝面的抗弯刚度,改善了普通渠道的接缝漏水问题;综合考虑构件预制、运输和施工等因素设计的渡槽式装配U形渠断面及跨度尺寸合理,满足结构受力要求,符合工程实际需要,适合在田间末级灌溉渠道中应用。     

Estimating potential costs and gains from an aquifer storage and recovery program in Australia

Artificial recharge of aquifer storage can provide water during drought periods, reverse falling groundwater levels and reduce water losses associated with leakage and evaporation, as compared with surface water storage. We examine the technical and economic potential of artificial storage and recovery for drought mitigation in the Murrumbidgee Region of New South Wales, Australia. Potential locations for infiltration basins and injection/recovery wells are identified according to criteria such as water availability, aquifer suitability, recharge potential, and potential to provide a usable resource. The estimated annual artificial recharge potential is 180,000 ML through a combination of injection wells and infiltration basins. The cost estimates for artificial recharge vary from AU$ 62 ML⁻¹ to AU$ 174 ML⁻¹ depending on the choice of recharge method. Underground storage capacity can be developed at less than half the cost of surface storage facilities without undesirable environmental consequences or evaporation losses. The estimated benefits of artificial storage and recovery through infiltration basins are three to seven times the costs, during low allocation years.     

Participatory water management at the main canal: A case from South Ferghana canal in Uzbekistan

After the independence of Central Asian countries, many international projects have been launched to promote water users’ inclusion into the water management at different levels. The aim of such projects is to achieve sustainable water management through inclusion of interests of different groups on day-to-day water management. Although IWRM in Central Asia has been already promoted for a decade, there are only a few examples of the implementation in real life situations.The Integrated Water Resources Management in Ferghana Valley (IWRM FV) is a pilot project on implementing integrated water resources management elements at the main canal levels and below. The experience gained from IWRM FV project and lessons learnt could be useful for the national and international organizations for their future work on IWRM implementation at the different regions of Central Asia.IWRM FV project has been active since 2001 in the Ferghana Valley, one of the largest irrigated areas of Central Asia. The project has promoted and implemented participatory irrigation management for three pilot canals. This paper presents the process of implementation and some preliminary outcomes of the IWRM VF project.     

Water management in tertiary units in the Fayoum,Egypt

The irrigation system in The Fayoum is designed for a continuous supply of water (24 h a day, 7 days a week) to rotational units, which vary in size from about 20 to 500 fe. The Fayoum Irrigation Department is responsible for the delivery of irrigation water to the rotational units. Within the units, the farmers rotate the water in a seven days rotation.One of the characteristics of present water management of The Fayoum is the non-uniformity of the division of flow over the main canals. The purpose of this paper is: (i) to study the effects of this non-uniformity by comparing water management in tertiary units in an area with a (more than) sufficient water supply to an area subject to some water shortage; (ii) to discuss implications of the present tertiary unit water management for the water management of the entire The Fayoum.The findings are that: (i) the non-uniformity of the main system water supply has a strong effect on the water management in the tertiary units. Water shortage results in a lower cropping intensity and fallow land, no possibility to cultivate rice, and a possible trend towards salinization in the Seila area; (ii) the farmers in both research areas modify the official rotation schedule. These modifications create a high flexibility in the rotational units: The water supply for different crops and plots is adjusted almost to the minute.Glossary and abbreviations Bahar Gate-Tender - FaWMDI Fayoum Water Management and Drainage Improvement Project - fe Feddan (1 fe = 0.42 ha) - FID Fayoum Irrigation Department - Ganabiah Secondary or Sub-Secondary - IIP Irrigation Improvement Project - Kafr Satellite Village of a Larger Village with a Mayor - Mesqah Tertiary Canal - MSL Mean Sea Level at Alexandria - Nasbah Cluster of Fayoum Standard Weirs - Sheikh el Balad The Oldest of the Kafr (Elected Position)     

Bonding of soil and of sediment cleaned from channels by cement into blocks for lining irrigation channels

Water diverted from rivers to canals and then to fields brings along a heavy sediment load. According to estimates, the elevation of irrigated fields in the Indus Basin has increased up to 8 cm due to deposition of sediment from irrigation water. The deposition of sediment in the canals, distributaries and watercourses is a common concern. Each year during the winter, the canals are closed for desilting the conveyance system. Sediment deposited in the farmer-managed watercourses is piled along the watercourse banks, which takes fertile land out of production. This study was conducted to evaluate the possibilities of preparing cement blocks with soils and with sediments removed from the watercourses and using them in low cost linings to decrease losses from watercourses. Soil–cement and sediment–cement blocks were prepared, and tested for strength, durability and ability to reduce losses from watercourses. Compositions of the soil and of the sediments removed from the channels were determined. Blocks mortared into walls lining the sides of these channels reduced losses to less than 20% of losses in unlined old channels. Plastering the inside of these walls reduced water losses to less than 1% of the losses occurring in old unlined channels. Sediment–cement blocks were easier to make and they develop greater strength than soil–cement blocks. Cost of channel lining, using these blocks, appears to be about 2/3 of costs using fired brick masonry.     

人民胜利渠灌区适宜井渠用水比研究

为合理利用灌区地表水和地下水资源,改善灌区生态环境,以人民胜利渠灌区为例,在对灌区地下水开发利用现状及其水位动态进行分析的基础上,将地下水模拟模型与GIS技术进行结合,并设置8个情景方案,预报了灌区5 a后地下水位变化趋势,并提出了灌区适宜的井渠用水比。结果表明,目前灌区地下水位呈不断下降趋势,削减灌区地下水开采量对地下水位的恢复有明显的作用。平水年削减10%的地下水开采量,人民胜利渠灌区井渠用水比例调整为1/0.78,上游调整为1/1.24,中游调整为1/0.85,下游调整为1/0.41,灌区机井数从原来的20 261眼削减到14 315眼,可以基本实现地下水的采补平衡。     

Water Delivery Performance in the Doroodzan Irrigation Scheme, Iran

Delivery performance ratio was used to assess thewater delivery performance in an irrigation district in theDoroodzan Irrigation System in Iran. The measurements wereapplied to three selected irrigation canals and their tertiaryoutlets during five consecutive irrigation cycles. The canalswere located at the head, middle and tail end of the irrigationdistrict.Performance indicators reveal that the physical system and themanagement could respond to the delivery of the intended supply.The indicators show a better reliability performance than theequity performance in water delivery at the tertiary outlets. Theresults from the Doroodzan Irrigation System reveal that thesystem could not deliver water according to the real crop waterrequirements. The actual overall efficiency was used to quantifythe water delivery performance in terms of deficit and excesswater. The equity and reliability performance was illustrated byusing the spatial and temporal variation of the expected overallefficiency at the district level.     

辽宁省实施农业节水灌溉的效果分析及建议

农业节水灌溉是缓解当前农业用水供需矛盾、提高水资源利用效率效益、落实水资源管理制度要求、推进节水型社会建设的重要举措.本文通过对辽宁省农业节水灌溉现状及实施农业节水灌溉的效果进行分析,对实施农业节水灌溉提出了几点建议.     

防渗渠道输水损失的估算

渠道防渗已成为我国大型灌区改造的主要手段 ,以提高水资源的利用率 ;如何估算防渗渠道的水量损失 ,已成为评价灌区改造的重要技术问题。在概括渠道输水损失的各种估算理论和方法的基础上 ,揭示了流量指数型估计式 σ=A/ Qm(% )对于防渗和非防渗渠道都具有广泛的适用性。并基于全国范围内的实测资料统计分析 ,对影响估计式参数的因素及规律性进行了深入分析 ,建议对防渗或非防渗渠道的渠道渗漏损失均采用该估计式 ,防渗渠道的参数可通过现场静水试验求得 ,或直接对透水性系数进行折减。