Irrigation performance before and after rehabilitation of a representative, small irrigation scheme besides the Senegal River, Mauritania

During the last quarter of the 20th century, many irrigation schemes were constructed along the bank of the Senegal River in Mauritania. About 40,000 ha were developed but less than 23,000 ha remain irrigated today. A program for rehabilitation is now in place to counteract deterioration and abandonment of these schemes. This paper presents an evaluation of the rehabilitation of a small, representative irrigation scheme governed by a farmers’ cooperative in the village of Bélinabé. Before rehabilitation, the scheme covered 37.7 ha comprising 107 plots each of 0.33 ha, essentially all devoted to production of rice. Water for irrigation was pumped directly from the river into two head basins and distributed through open canals. After rehabilitation, the scheme was extended to 115 ha with new plots averaging 0.36 ha. Water is now supplied by a single cluster of pumps and conveyed through pipes and open canals. Evaluation of performance consisted in analysis of: capacity; distribution losses; flexibility, adequacy and reliability of the system; maintenance status; farmer's perception of system performance. Field data were collected during irrigation campaigns before rehabilitation in 2004 and during 2006 and 2007 afterwards. A model of network distribution and field water balance was developed to assist evaluation. It was established that before rehabilitation the scheme could operate satisfactorily if proper maintenance were practiced. After rehabilitation, more families have access to irrigation but reliability and flexibility of water distribution have been reduced. Furthermore, pumping capacity is now insufficient to cover crop water requirements. Recommendations are provided for future rehabilitation work and maintenance of schemes generally.     

Resource-centred thinking in river basins; should we revoke the crop water requirement approach to irrigation planning?

The paper examines the method of using project irrigation requirements (PIR) in the design and rehabilitation of small-scale smallholder irrigation systems within multi-sector and dynamic river basins. This procedure, which employs equations that determine irrigation and crop water requirements, is found embedded in irrigation thinking and planning methodologies throughout the irrigation world. The paper argues that if the PIR equations are used formally and conventionally without sufficiently accounting for changing demands for water in semi-arid river basins, they can lead to irrigation designs that over-prioritise water for individual irrigation systems and as such be labelled ‘irrigation-centred’. Although other adjustments and attempts at re-allocating water might be undertaken, basin managers are often unable to recognise, accommodate or transcend the irrigation focus that this approach generates thus curtailing the efficacy of re-allocation efforts. This argument is made on the basis of observations in the Usangu Plains of Tanzania of farmer-originated irrigation and donor attempts at rehabilitation and modernisation. Features of a modified planning and design methodology are suggested, which considers irrigation alongside other water sectors, and focuses on the river basin rather than on the individual system; an alternative which, it is proposed, is more flexible and ‘water-resource-centred’. The implications of this dualism in approaches (irrigation-centred or resource-centred) for basin management, livelihoods, conflict mediation and formal irrigation rehabilitation projects are explored.     

Managing the water balance of The Fayoum Depression,Egypt

A study of the water balances of The Fayoum irrigated lands and Lake Qarun was made to investigate the management of the irrigation system and the efficiency of irrigation water use. The two water balances are strongly interrelated. The drainage flow to Lake Qarun and the water level of the Lake are in delicate balance. A rise in Lake level causes the inundation of adjacent land. Management of The Fayoum water balance assumes control over irrigation water flows, but this control has technical and organizational limitations. Also discussed is the influence of irrigation practices in The Fayoum on the water balance (e.g., the autumn flushing of fields and farmers' preference for not irrigating at night in winter). Notwithstanding a high overall efficiency, irrigation efficiency during the winter is low. The reasons for this are given, together with the constraints against improving system management. Improved uniformity of the division and application of irrigation water will enable a better technical control of flows and will result in better water management in The Fayoum. Abbreviations: FID — Fayoum Irrigation Department, 1 feddan (fe) — 0.4 ha, 1 mcm — 1 million cubic metres: an average annual flow of 3.17 m³/s gives 100 mcm, m³/fe.year — supplied volume (m³) per surface area (fe) per year: 1000 m³/fe.year equals 240 mm/year, MSL — Mean Sea Level     

大型灌区节水改造经济评价

根据所收集大型灌区节水改造相关资料,以层次分析法和模糊数学理论为基础建立了大型灌区节水改造经济评价模型.在此评价模型中,利用层次分析法建立了大型灌区节水改造投资效益分析的谱系结构,并根据模糊数学确立相应的大型灌区节水改造投资效益评价指标体系及其参数.最后利用模型对我国中、西部典型灌区--韶山灌区和青铜峡灌区节水改造进行了经济评价,并对评价结果进行了讨论,说明了模型和方法的有效性,同时说明了我国西部大开发的必要性.     

Reductions in water use following rehabilitation of a flood-irrigated area on the Murray River in South Australia

Water use was monitored during rehabilitation of flood-irrigated farms in the lower Murray River of South Australia. Ten irrigation offtakes at six farms were monitored over a period of two years during the rehabilitation process. Full rehabilitation consisted of improved inlet structures, flow metering, elimination of water leaks, laser levelling of paddocks, and construction of re-use systems to recycle excess surface irrigation runoff. Partial rehabilitation consisted of the same improvements with the exception of the re-use system. The mean water use per watering of 0.61 ± 0.08 Ml/ha for the fully rehabilitated farm was approximately one third of that for non-rehabilitated farms (1.89 ± 0.15 Ml/ha) and two thirds of that for partially rehabilitated farms (0.99 ± 0.07 Ml/ha). These differences were statistically significant at the 95% confidence level. A large improvement in efficiency of water use was achieved by upgraded water delivery infrastructure and laser levelling of paddocks. Considerable improvement in water use efficiency was also gained, however, only by installation of re-use systems. It is expected that the overall rehabilitation of irrigation infrastructure will result in a significant reduction of water extracted from the river for flood irrigation in this region. Further longer term monitoring is required to confirm this.     

Development of the irrigation M&O learning process

A learning process has been developed, based on experiences in Thailand, Sri Lanka and Nepal, for improving the maintenance and operations practices of an irrigation project or system. This learning process has been designed to:

minimize the investment (O&M) costs so as to avoid rehabilitation;

increase credibility of irrigation project staff with central headquarters through improved financial management practices and accountability; and

develop more knowledge about what is occurring within the system in order to meet the needs of farmers.

     

Integration of engineering,institutional and social requirements into rehabilitation design. A case study from Nepal

The paper describes the engineering approach which was adopted by irrigation engineers in collaboration with sociologists to address the technical, institutional and social constraints found in a study for rehabilitation of a Government run irrigation scheme in Nepal. Designs were evolved to provide a system which was easy to operate, made abuse of the system easy to identify, and encouraged farmer cooperation and the formation of water user groups.     

VR-GIS技术在渠系建筑物管理中的应用研究

灌区渠系建筑物的更新改造工程迫切需要掌握灌区的现状,传统的二维信息系统、二维GIS系统难于表达具有时间、空间和属性等多维信息的渠系建筑物。应用VR-GIS技术构建了宝鸡峡杨凌二支渠灌区渠系建筑物管理系统,探索虚拟管理的实现技术。应用结果表明基于VR-GIS技术的系统能满足灌区渠系建筑物的信息化管理要求。该系统用户界面友好,能大大提高管理的效率。     

东港灌区运行状况综合评价研究

在灌区续建配套与节水改造规划工作实施的基础上，拟建了一套合理的评价指标体系，利用层次分析法（AHP）确定评价指标的权重，建立了模糊综合评判（FCE）数学模型，并运用该模型对东港市的三个灌区的运行状况进行综合评价，评价结果与实际情况吻合良好。     

渠系网络图在大型灌区规划中的应用

渠系规划是大型灌区续建配套与节水改造规划的重要内容。简要介绍了渠系网络图的特点、绘制的方法和绘制的意义，通过在灌区规划中的应用表明，采用这种图形能从整体上直观清晰地反映灌区灌排渠系布置情况，既便于规划中有关设计参数的推求，又便于灌区管理人员参考。     

Evaluating water delivery in tertiary units Part 2: A case study,Urcuqui, a farmer-managed irrigation system in the Andes

We study the actual water distribution within a small Ecuadorian farmer-managed irrigation system, where water is distributed according to the flexible rotation mode. The analysis of distribution rules raises the first potential problem: individual water rights are excessive and may lead to considerable water losses and to inaccurate rotation length. Actual irrigation events are then measured during 1 year (two cropping periods). We notice the variability of the collected flow, which haphazardly affects each plot and probably led to the users' long-term strategies, i.e. a progressive increase of water rights. We also observe very low intensity irrigation practices: individually or collectively, users often choose not to irrigate. These strategies affect the global system functioning and the real access to water for each plot. Globally, the fulfilment of the crop's water needs is inadequate and rain dependent, even when the present water supply at the inlet is sufficient. We also observe a great variety of users' strategies. This variety is studied through cluster analysis. Finally, the use of new methods presented in the companion paper (Part 1) allowed us to analyse the actual system in Urcuqui, and to identify the most important causes of failure, which are now corrected through a rehabilitation project.     

宁夏大型灌区续建配套与节水改造项目——以第二农场渠为例

宁夏大型灌区续建配套与节水改造项目自1998年启动实施以来,灌区骨干工程安全状况有了较大改观,渠道综合调控能力不断增强,全灌区节水意识进一步提高,灌区“两改一提高”工作稳步推进,除险保安、节水增效成果显著。但由于灌区水利工程大多是20世纪五六十年代在原有基础上改造和修建的,灌区规模大,历史遗留问题多,水利基础设施薄弱,改造需求量大,加之投入有限,目前灌区仍存在水资源综合调控体系不完善、渠道砌护率低、大型泵站老化严重、沟道排水不畅、骨干渠系防洪体系脆弱、管理设施差等突出问题,灌溉水利用系数只有0.41,成为全国老化失修最严重的灌区之一。      

黄河流域典型灌区灌溉节水管理模型研究

以黄河流域上下游2个典型灌区为背景，针对灌区有其农业水管理现状，开发了灌溉节水策略分析决策支持系统（DSS）原型。DSS是一个规划工具，通过对不同策略下田间配水及供水系统的模拟分析及综合决策，寻求最优的策略集合，以达到节约灌溉用水量、提高农业用水效率及维持农业可持续发展的目的。该DSS系统主要用于黄河流域灌区提高农业水管理水平的策略分析，也可用于评估灌区续建配套及土地最佳利用方案等方面。     

User charges in irrigation: Potentials and limitations

Interest in systems of user charges for irrigation projects serving large numbers of small farmers has grown in recent years in response to concerns about

-the need to provide more adequate funding of O&M,

-distortions and inefficiencies induced by subsidies, and

-inadequate accountability of irrigation system managers to water users.

The effects that can be expected from a system of user charges depend on

-whether the charges are assessed as water prices or as area-based fees,

-whether the irrigation agency has a significant degree of financial autonomy, and

-the nature of the linkages between irrigation charges and investment decisions.

Other important considerations in establishing user charges are the ability of the users to pay irrigation fees; the cost-effectiveness of O&M activities; the costs of implementing the user charges; and whether charges are project-specific or uniform throughout a region or a nation.     

The use of measured water flows in furrow irrigation management — a case study in Swaziland

The use of measured water in controlling flows for the irrigation of sugarcane was found to be vital for the rehabilitation and management of surface irrigation on a 5000 ha sugarcane project. Methods of water delivery, measurement and control at Inyoni Yami Swaziland Irrigation Scheme (IYSIS) are described. Improvements to the irrigation, using existing methods of water measurement, were carried out over a period of four years. The lessons gained in this programme of improvements confirmed the benefits of using modulus gates which allow a constant, measured, discharge of water.     

Agricultural and environmental changes after irrigation management transfer in the Develi Basin,Turkey

Develi Basin is a semi-arid basin in central Turkey where water sustains both irrigated agriculture and an internationally important wetland, the Sultan Marshes. Agricultural and environmental changes in the Develi Basin have occurred since irrigation management was transferred in 1994 from a state authority (DSI) to irrigation associations (Kovalı and Ağcaaşar IAs). In this paper we evaluate the practices of the IAs using extensive data from interviews with farmers and IA officials, as well as data from reports prepared by DSI and the IAs, using comparisons with case studies reported in the scientific literature. Irrigated areas and surface water use in the Develi Basin showed significant fluctuations from 1995 to 2003. The area allocated to high water-consuming plants increased. Maintenance activities became dependent on fee collection rates. Quality of the irrigation water did not changed significantly. Ground-water levels, flow rates from springs, and water levels in the Sultan Marshes all dropped. Overall analyses indicate that the water requirements of the Sultan Marshes have not been met, while water use for irrigation has been effective but not efficient. To reconcile agricultural and wetland water requirements, a basin-wide approach in water planning is recommended. Amounts of water to be allocated to the IAs and wetlands need to be clearly defined. DSI has to monitor canal maintenance by the IAs more closely, and IAs need to be given more responsibilities for future rehabilitation of the canals. Realistic water pricing, increased reliability of irrigation scheduling, higher on-farm irrigation efficiency, and in the long-term, modernization of the irrigation system need to be considered.     

Modernization of furrow irrigation in the South-East of France automation at field level and its implications

Surface irrigation rehabilitation in the South-East of France has shown success ever since the beginning of its development in the early 1980s. The gradual introduction of surface distributors, mechanized or automated has resulted in water savings and above all in decreased labor input. The distributors used are: gated pipes, layflat tubing, buried low pressure pipe and cablegation. They are used over an ever increasing area which attained about 1000 ha in 1987.Improvement is made in furrow head distribution as well as in field levelling, furrow flow evaluation, flow control at the head of the furrow and in the collective system.The effect of a modernized system and improved knowledge has been to make automated surface irrigation (particularly furrow irrigation) a modern application method in competition with techniques such as sprinklers and localized irrigation.Abbreviations ASAE American Society of Agricultural Engineers - CEMAGREF Centre d'Etude du Machinisme Agricole du Génie Rural des Eaux et des Forêts, Division Irrigation, BP 5095, 34033 Montpellier et BP 31 Le Tholonet 13612 AIX - ENGREF Ecole Nationale du Génie Rural des Eaux et des Forêts, Département Maîtrise de l'Eau et Développement, BP 5093, 34033 Montpellier - IRAT Institute de Recherche en Agronomie Tropicale, Zolad Mini Parc Bt7, 34100 Montpellier - P.V.C. Polyvinyl chloride - RNEDHA Réseau National Expérimentation Démonstration secteur Hydraulique Agricole, BP 5095, 34033 Montpellier - SCP Société du Canal de Provence et d'Aménagement de la Région Provençale, BP 100, 13603 AIX en Provence     

The rehabilitation of an irrigation system along the Yellow River

The People's Victory Irrigation System which diverts water from the Yellow River of China covers a total irrigable area of 59 000 ha. The system encountered some serious problems in the first decade of its operation — salinity and waterlogging of irrigated land, siltation of irrigation and drainage channels, as well as a low efficiency of water use. This paper describes a series of structural and functional measures which have been adopted in the past 24 years for the rehabilitation of the system, including: improvement of the existing drainage system and construction of new drainage system on agricultural land, conjunctive use of surface and groundwater supplies, a comprehensive programme to reduce the levels of siltation as well as the implementation of improved water management practices. A model for the optimal operation of the system by using system analysis theory as an aid in reducing the operation and maintenance (O & M) costs has been developed in recent years. The results are that the soil salinity has been controlled and the agricultural production has increased whilst the efficiency of water use has improved and the siltation levels reduced. Experience gained on this system has been successfully used in developing and managing other irrigation projects along the lower reaches of the Yellow River. The proposed procedure of solving the said optimal model has also embodied some benefits from reducing O & M costs in operation.     

Partial rootzone drying is a feasible option for irrigating processing tomatoes

World water supplies are limited and water-saving irrigation practices, such as partial rootzone drying (PRD), should be explored. We studied the effects of PRD, applied through furrow and drip irrigation, on plant water relations, yield, and the fruit quality of processing tomato (Lycopersicon esculentum Mill. cv. ‘Petopride’). There were four treatments. The first two were: full irrigation by hand on both sides of the root system which mimicked furrow irrigation (FuI), and half of irrigation water in FuI given alternately only to one side of the root system with each irrigation (PRD_FuI). The next two treatments were: full drip irrigation (DrI) to both sides of the root system, and half of irrigation water in DrI given alternately only to one side of the root system with each irrigation (PRD_DrI). Leaf water potential was the same among the treatments except for the PRD_FuI plants, which had the lowest midday values only in one sampling out of four. Photosynthetic rate was the same among the treatments except for the drip-irrigated plants having the lowest value in one sampling out of four. Number of fruit, mean fruit mass of fruit, total fresh and dry mass of fruit, and harvest index were the same among treatments, but PRD plants had increased irrigation use efficiency compared to fully irrigated plants. There was no incidence of blossom-end rot in any of the treatments. PRD_DrI fruit had redder colour and higher total soluble solids concentration. Advancement in fruit maturity and enhancement of quality could be achieved without detrimental effect on fresh and dry mass of fruit by application of PRD. Independent of the irrigation method, PRD treatments improved irrigation use efficiency by ca. 70%. PRD has the potential for use in processing tomato especially in environments with limited water.     

Management model for decision support when applying low quality water in irrigation

Use of low quality water for irrigation of food crops is an important option to secure crop productivity in dry regions, alleviate water scarcity and recycle nutrients, but it requires assessment of adverse effects on health and environment. In the EU-project “SAFIR¹” a model system was developed that combines irrigation management with risk evaluation, building on research findings from the different research groups in the SAFIR project. The system applies to field scale irrigation management and aims at assisting users in identifying safe modes of irrigation when applying low quality water. The cornerstone in the model system is the deterministic “Plant-Soil-Atmosphere” model DAISY, which simulates crop growth, water and nitrogen dynamics and if required heavy metals and pathogen fate in the soil. The irrigation and fertigation module calculates irrigation and fertigation requirements based on DAISY's water and nitrogen demands. A Water Source Administration module keeps track of water sources available and their water quality, as well as water treatments, storage, and criteria for selection between different sources. At harvest, the soil concentrations of heavy metals and pathogens are evaluated and the risk to consumers and farmers assessed. Crop profits are calculated, considering fixed and variable costs of input and output. The user can run multiple “what-if” scenarios that include access to different water sources (including wastewater), water treatments, irrigation methods and irrigation and fertilization strategies and evaluate model results in terms of crop yield, water use, fertilizer use, heavy metal accumulation, pathogen exposure and expected profit. The management model system can be used for analysis prior to investments or when preparing a strategy for the season.