On-farm performance evaluation of improved traditional small-scale irrigation practices: A case study from Dire Dawa area, Ethiopia

Field evaluation of surface irrigation systems play a fundamental role to determine the efficiency of the system as it is being used and to identify management practices and system configurations that can be implemented to improve the irrigation efficiency. This study evaluated the performance of an ‘improved’ traditional small-scale irrigation practice at Adada, a representative small-scale irrigation practice in Dire Dawa Administrative Council, Eastern Ethiopia. In order to determine numerical values of performance measures, certain parameters were measured/observed before, during and after an irrigation event while farmers are performing their normal irrigation practice. These parameters include: irrigated crop, irrigation method, stream size, cutoff time, soil moisture deficiency, and field size, shape and spacing. The results showed that the irrigation water applied to a farmer's plot during an irrigation event/turn was generally higher than the required depth to be applied per event. Since the irrigation method used was end-dyked, the major cause of water loss was due to deep percolation. The deep percolation loss was 32% in sorghum, 57% in maize, and 70% in tomato and potato fields. The type of irrigation system used, the ridged irrigation practice and the poor irrigation scheduling in the study sites were the main problems identified in the management and operations of the schemes. The following corrective measures are recommended to improve the system: (1) farmers should regulate the depth of irrigation water they apply according to the type of crop and its growth stage, change the field irrigation system and/or configuration especially for shallow rooted row crops, to furrow system, (2) guidance and support to farmers in developing and introduction of appropriate irrigation scheduling, and (3) future development interventions towards improvement of traditional irrigation practices should also focus in improving the on farm irrigation systems in addition to improving physical infrastructure of the scheme.     

Diagnosis of regional evaporation by remote sensing to support irrigation performance assessment

The success of water management in large irrigation schemes with composites of soil, crop, wetness and micro-meteorological conditions is difficult to quantify. Performance assessment indicators, being among others a function of evaporation, are useful tools to evaluate the actual functioning of an irrigation system. The inevitable spatial variability of evaporation in large irrigation schemes makes its determination with conventional point measurements almost impossible. A new remote sensing evaporation parameterization algorithm has been tested with high resolution Landsat Thematic Mapper data for the Eastern Nile Delta, Egypt. Although the implementation of such an algorithm requires assumptions to be made, the current case study shows that these assumptions do not hamper the estimation of actual and potential evaporation at regional scale. The actual evaporation has been used to express the uniformity of crop water use which is related to the equity of irrigation water distribution. The coefficient of variance in actual evaporation between 53 differenent irrigation districts is 10% on average. The relative evaporation was considered to determine whether the crop was adequately irrigated. The relative evaporation was more than 75% for 48 out of 53 irrigation districts. It is concluded, that improved information on actual crop growth conditions through remote sensing provides an essential insight into the planning of real-time and seasonal irrigation water deliveries.     

山东禹城引黄灌区非充分灌溉配水模型

为了制定有多种作物且灌溉水源为动态变化的灌区的配水计划，提出了由充分灌溉和非充分灌溉2级模型组成的配水模型。其中非充分灌溉配水模型包括优化模型和模拟模型2部分，优化模型的方案具有较好的经济效益，而模拟模型的方案便于实施。模型中联合运用引黄水和地下水，可减少因黄河缺水对农业造成的重大损失。在此基础上编制的山东禹城灌溉配水管理决策支持系统界面友好，实用性强，基本上可灌溉灌区的管理需要。     

Usefulness and limitations of decision support systems for improving irrigation scheme management

SIMIS (the FAO Scheme Irrigation Management Information System) is a decision support system that integrates tools and performance indicators to facilitate the planning and management of irrigation schemes. The authors used SIMIS to compute performance indicators in an irrigation scheme in Southern Spain that were used to identify distribution system constraints affecting the flexibility of water deliveries and to identify scheme sectors where deliveries could not meet the predicted crop water demands. Applying SIMIS, the authors and the irrigation scheme manager evaluated measures to overcome the constraints for future irrigation campaigns, and to refine the water orders made every 2 weeks to the basin authority. On the other hand, SIMIS presented limitations to the evaluation of on-demand delivery schedules. To overcome these limitations, an external model, developed outside SIMIS, showed that the current distribution network of the scheme has the capacity to deliver water on-demand only if a slight water deficit is accepted during the peak demand period. The analysis showed that by relaxing the stringency of the quality of operation of on-demand systems, rotation systems may be transformed into on-demand systems without changing their structures. This analysis could also be done using Clément's hypothesis, but doing so resulted in overestimates of the quality of operation and of the relative irrigation supply.     

An evaluation of the performance of six smallholder irrigation schemes in Zimbabwe

Informal and formal survey procedures were used to assess the performance of six smallholder irrigation schemes. The predominant crops grown at the schemes were maize (Zea mays) in summer and beans (Phaseolus vulgaris) in winter. Average crop yields range from 2.7 to 7.4 t/ha for maize and 0.4 to 2.4 t/ha for beans at the lowest and highest yielding schemes respectively. There was also a large gap between the lower and higher producing farmers at each scheme. Only one out of the six schemes realized a profit margin of more than ZWD 223 per month per plotholder (the minimum wage rate for agriculture workers) after operating and maintenance costs (currently met by government) were deducted. Major constraints on the schemes included limited cash for input purchases, unreliable water supplies for winter cropping, limited market outlets and poor roads. Ways of alleviating some of these constraints to improve overall scheme performance are proposed.     

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.     

Flexible delivery schedules to improve farm irrigation and reduce pressure on groundwater: a case study in southern Italy

This study was conducted on an irrigated area of southern Italy to analyze the current operation of a large-scale irrigation delivery system and the effects of the operation procedures on crop irrigation management and aquifer salinity increase. The area is characterized by relatively high levels of groundwater salinity in the summer that are probably due to intensive groundwater pumping by farmers during periods of peak irrigation demand, with the resulting seawater intrusion. Two alternative delivery schedules, namely the rotation delivery schedule and the flexible delivery schedule, referred to as RDS and FDS, respectively, were simulated using a soil-water balance model under different combinations of crop, soil and climatic conditions. The first set of simulations concerned the farm irrigation management constrained by the rotational delivery used by the local water management organization. The second scenario simulated the farm irrigation schedule most commonly used by growers in the area for maximizing crop yields. Based on crop irrigation management under RDS and FDS, two alternative operational scenarios were also developed at the scheme level and then compared for evaluation. Winter and summer salinity maps of the aquifer were developed by interpolating salinity measurements of the groundwater samples collected during the 2006 irrigation season. From these maps, a close relationship can be inferred among delivery schedule, aquifer exploitation and salinity increase, which justifies the need for implementing FDS that might reduce the groundwater demand for irrigation.     

A measure for the efficiency of water use and its determinants,a case study of small-scale irrigation schemes in North-West Province,South Africa

This paper analyses the efficiency with which water is used in small-scale irrigation schemes in North-West Province in South Africa and studies its determinants. In the study area, small-scale irrigation schemes play an important role in rural development, but the increasing pressure on water resources and the approaching introduction of water charges raise the concern for more efficient water use. With the data envelopment analysis (DEA) techniques used to compute farm-level technical efficiency measures and sub-vector efficiencies for water use, it was shown that under constant returns to scale (CRS) and variable returns to scale (VRS) specification, substantial technical inefficiencies, of 49% and 16%, respectively, exist among farmers. The sub-vector efficiencies for water proved to be even lower, indicating that if farmers became more efficient using the technology currently available, it would be possible to reallocate a fraction of the irrigation water to other water demands without threatening the role of small-scale irrigation. In a second step, Tobit regression techniques were used to examine the relationship between sub-vector efficiency for water and various farm or farmer characteristics. Farm size, landownership, fragmentation, the type of irrigation scheme, crop choice and the irrigation methods applied showed a significant impact on the sub-vector efficiency for water. Such information is valuable for extension services and policy makers since it can help to guide policies towards increased efficiency.     

温室番茄节水调质灌水方案评价

为寻求日光温室番茄优质高效的灌溉制度,采用设置于温室番茄冠层齐平位置的水面蒸发测定装置,设计3种基于水面蒸发量的灌水间隔水平和4种灌水量水平组合处理,依据小区试验观测结果,分析确定了以番茄产量、水分利用率、单果重、可溶性固形物质量分数及果实硬度等5项指标为主的节水调质灌溉制度评价体系;在采用变异系数法确定出各指标权重的基础上,借鉴TOPSIS综合评价方法,建立了温室番茄节水、优质、高产相统一的综合评价模型,应用该模型确定基于水面蒸发量的温室番茄节水调质灌溉制度,即当累积水面蒸发量Epan达到10mm±2mm时进行灌溉,灌水量为0.9Epan,在产量不降低的情况下,提高了水分利用率,并在一定程度上提高了果实的营养品质和储运品质.     

Simulation of peak-demand hydrographs in pressurized irrigation delivery systems using a deterministic–stochastic combined model. Part I: model development

This study describes a model named HydroGEN that was conceived for simulating hydrographs of daily volumes and hourly flow rates during peak-demand periods in pressurized irrigation delivery networks with on-demand operation. The model is based on a methodology consisting of deterministic and stochastic components and is composed of a set of input parameters to reproduce the crop irrigation management practices followed by farmers and of computational procedures enabling to simulate the soil water balance and the irrigation events for all cropped fields supplied by each delivery hydrant in a distribution network. The input data include values of weather, crop, and soil parameters, as well as information on irrigation practices followed by local farmers. The resulting model outputs are generated flow hydrographs during the peak-demand period, which allow the subsequent analysis of performance achievable under different delivery scenarios. The model can be applied either for system design or re-design, as well as for analysis of operation and evaluation of performance achievements of on-demand pressurized irrigation delivery networks. Results from application of HydroGEN to a real pressurized irrigation system at different scales are presented in a companion paper (Part II: model applications).     

Irrigation water prices for farmer-managed irrigation systems in Tanzania: a case study of Lower Moshi irrigation scheme

A computer program model for pricing irrigation water among beneficiaries was developed and tested. The data used for the purpose was collected from Lower Moshi farmer-managed irrigation scheme (FMIS) in northern part of Tanzania as a case study. The scheme has two intakes; namely Rau and Mabogini irrigation systems. Allam's mathematical model for allocating irrigation water price which was developed in Egypt (Allam, 1987) was adopted and adapted for the purpose. The results indicate that the irrigation water price depends on a number of structures serving the area, their installation costs, amount of water received by each tertiary block and water rights. The prices differ between different tertiary blocks within the same system and also between two systems that exist in Lower Moshi Irrigation Scheme (LMIS). This indicates that the model can be used as a tool by designers and planners for selecting the best designed irrigation system that farmers can afford to pay for its operation, maintenance and management. The mean irrigation water price value for Mabogini is Tshs. 12 151/-¹ while that of the Rau system is 10 414/-. To maintain uniformity of irrigation water price in the scheme, it is recommended that a mean value of Tshs. 11 283/- is used. Generally, farmers in Tanzania are used to contribute one bag of paddy which costs about Tshs. 10 000/- for maintenance works. Therefore, the irrigation water price derived from the model is reasonable and one the farmers can afford.     

A comparison of two methodologies for assessment of irrigation performance under the Warabandi system

A water management study of Warabandi in northwest India in 1983 developed a methodology for assessing the performance of large scale smallholder irrigation schemes by observing irrigated areas and carrying out random crop cutting. A study of Warabandi in 1988 took a shorter amount of time and concentrated on direct measurements of flow and seepage in order to assess the performance of the physical conveyance system. This paper contrasts these two approaches and gives practical guidance on how to go about carrying out a rapid assessment of the performance of the physical conveyance system of an irrigation scheme.     

Drip Planner Chart: a simple irrigation scheduling tool for smallholder drip farmers

Drip irrigation is widely recognized as potentially one of the most efficient irrigation methods. However, this efficiency is often not achieved because systems are not always well designed or maintained and many farmers lack the tools to assess the crop water requirements and to monitor the soil moisture conditions in the field. There is a vast amount of literature on irrigation scheduling but little literature takes scientific information the next step by preparing practical guidelines for smallholder farmers. There is a large and widening gap between the state of the art irrigation scheduling tools and current on-farm irrigation practices. Most farmers find current irrigation scheduling tools overwhelming and lack the means and skills to install and operate them. It is suggested that farmers need simple, cheap and more comprehensive support tools to achieve improved irrigation management at the farm level. Wageningen University and Research Centre (WUR) developed the Drip Planner Chart (DPC) to provide smallholder farmers with a simple tool to schedule drip irrigation to the crops?? needs. DPC is a manual disk calculator to calculate daily irrigation requirement. Farmers?? feedback was the basis for developing the DPC. Using DPC over a three-year period in Spain resulted in a 14 % water saving and improved irrigation timing. Trials at smallholder farmer fields in Nepal and Zambia showed DPC advice is more adapted to the changing demands of the crop over the different growth stages and responds to the farmer??s quest for practical drip scheduling advice. This paper presents the Drip Planner Chart and the scientific validation of the accuracy of the DPC. Experiments on farmers?? fields show water saving in Nepal and improved yield in Zambia. In both countries an improved scheduling over the growing seasons was found using DPC.     

The evolution of smallholder irrigation policy in Zimbabwe: 1928–1986

Voluntary smallholder irrigation schemes in Zimbabwe were launched in 1913 as a means of famine relief and subsequently to settle black farmers displaced from designated areas for white commercial farmers. In 1928 the colonial government inaugurated a programme to provide services to existing smallholder schemes and to assist in developing new schemes. This process eventually led to the erosion of farmer participation in planning, development and financing of smallholder schemes. Since 1928 the smallholder schemes have been heavily subsidised, a pattern that continues today. Currently about 3.4% of the land under irrigation is farmed by small holders who pay about 11% of the costs of irrigation operation and maintenance; the remaining 89% is subsidised by the government. More smallholder irrigation development is currently being planned. The government has made loan funds available to groups on the basis of financial viability, but to date this fund has not been significantly utilized by smallholders. In essence, smallholder irrigation development is being constrained by problems that have plagued smallholder schemes since 1928.Abbreviations AGRITEX Agricultural Technical and Extension Services - ARDA Agricultural and Rural Development Authority - DERUDE Department of Rural Development - NFIF National Farm Irrigation Fund - Z$ Zimbabwe Dollar     

Irrigation operation and maintenance in Vietnam under economic restructuring

Vietnam's policies to establish a market economy are reshaping the state organizations and agricultural cooperatives that have operated and maintained irrigation systems. The new policies emphasize financial autonomy for state enterprises, and a shift in the responsibilities of the agricultural cooperatives away from collective production activities. Specific policies and institutional arrangements vary considerably among the provinces. In Quang Nam-Da Nang province in central Vietnam, the agricultural cooperatives generally still play an important role in irrigation O&M at the tertiary and quaternary level, serving as intermediaries between individual households and the state enterprise that operates the headworks and the primary and secondary canal network of government irrigation schemes. The cooperatives also have full responsibility for many small pump irrigation schemes. The state irrigation enterprises have partial financial autonomy, financing their activities primarily from irrigation fees collected from the farmers. The power to set the fees, however, resides with the provincial government and not with the irrigation enterprises. The fee, which is an area-based fee differentiated by crop and season, is set in terms of paddy to facilitate maintaining its real value in the face of inflation. Both cost and equity factors are taken into consideration in setting the schedule of fees. The fees in government gravity irrigation schemes are fairly high by comparison with other Asian countries; however they are lower than typically paid by farmers in the small pump irrigation schemes operated by the agricultural cooperatives.     

奎屯河灌区水资源管理模式探析

新疆奎屯河灌区是全国主要大型灌区之一，是灌区管理改革试点地区之一，对该灌区实行的政府计划和市场结合配置水资源的管理模式进行了有意义的实证研究，认为在这种形式下的水资源管理必须制定相应合理的水价体系,才能确保农户积极的节约用水,起到与建立水市场同样合理使用水资源的作用,同时建立水资源的合理核算机制也有利于缓解管理者与农户之间的矛盾.得到的分析结果对今后灌区的管理具有良好的参考价值.     

Performance assessment of irrigation water management of heterogeneous irrigation schemes: 1. A framework for evaluation

Studies of the performance assessment of irrigation schemes have gained momentum since the late 1980s due to the common perspective that the resources (land and water) in irrigation schemes are not being managed appropriately. In this paper irrigation water management is considered as one of the activities of the irrigation scheme. Three phases of irrigation water management namely planning, operation and evaluation are identified. A framework for the performance assessment of irrigation water management in heterogeneous irrigation schemes is proposed in this paper, based on earlier studies made in this direction. The paper presents two types of allocative measures (productivity and equity) and five types of scheduling measures (adequacy, reliability, flexibility, sustainability and efficiency), together with the methodologies for estimating these for the scheme as a whole during different phases of irrigation water management.     

Didactic tools for supporting participatory water management in collective irrigation schemes

In many irrigation schemes, Water Users Associations (WUAs) acquired the responsibility for water management after withdrawal of the state. Based on the success of some indigenous irrigation schemes, it was assumed that farmers could easily become managers. As decision-making was the exclusive terrain of the governmental agencies that ran the schemes, farmers never gained the necessary experience with water management. Therefore, training of farmers and WUAs on the principles and processes of water management is essential. This paper demonstrates a practical example of training material on water management that incorporates research results on the process of Irrigation Management Transfer and resulting farmers’ water management for the case of the Office du Niger irrigation scheme. The results of the paper explain how input from research was used in the four steps of the construction of training material. These steps are (1) setting the training agenda, (2) selecting and adapting information to be featured, (3) targeting the audience and (4) designing the actual training material. A first validation of the approach and examples of the actual training material were obtained in a workshop uniting all stakeholders.     

Aflaj irrigation and on-farm water management in northern Oman

This paper reports on results from a case study on water management within a traditional, falaj irrigation system in northern Oman. In the planning and design of regional irrigation development programs, generalized assumptions are frequently made as to the efficiency of traditional surface irrigation systems. Although qualitative accounts abound, very little quantitative research has been conducted on on-farm water management within falaj systems. Daily irrigation applications and crop water use was monitored during an 11-month period among 6 farm holdings at Falaj Hageer in Wilayat Al-Awabi. Contrary to the frequent assumptions that all surface irrigation systems incur unnecessarily high water losses, on-farm ratios of crop water demand to irrigation supply were found to be relatively high. Based on actual crop water use, irrigation demand/supply ratios among monitored farms varied from 0.60 to 0.98, with a mean of 0.79. Examination of the soil moisture budget indicates that during most irrigations of wheat (cultivated in the low evapotranspiration months of October–March) sufficient water is applied for the shallow root zone to attain field capacity. With the exception of temporary periods of high falaj delivery flows or periods of rainfall, field capacity is usually not attained during irrigations within the more extensive root zones of date palm farms. The data presented in this paper should provide a better understanding of water use performance by farmers within traditional falaj systems. Moreover, these data should also serve to facilitate more effective development planning for irrigation water conservation programs in the region.