Adapting to intersectoral transfers in the Zhanghe Irrigation System, China: Part I. In-system storage characteristics

The Zhanghe Irrigation System (ZIS), in Central China, has drawn attention internationally because it managed to sustain its rice production in the face of a dramatic reallocation of water to cities, industries and hydropower uses. Ponds, the small reservoirs ubiquitous in the area, are hypothesized to have been instrumental in this. Ponds are recharged by a combination of return flows from irrigation and runoff from catchment areas within the irrigated perimeter. They provide a flexible, local source of irrigation water to farmers. This paper assesses the storage capacity and some key hydrological properties of ponds in a major canal command within ZIS. Using remote sensing data (Landsat and IKONOS) and an area–volume relationship based on a field survey, we obtained an overall pond storage capacity of 96 mm (per unit irrigated area). A comparative analysis between 1978 and 2001 reveals that part of this capacity results from a very significant development of ponds (particularly in the smaller range of sizes) in the time interval, probably as a response to rapidly declining canal supplies. We developed a high-resolution digital elevation model from 1:10,000 topographic maps to support a GIS-based hydrological analysis. Pond catchments were delineated and found to extensively overlap, forming hydrological cascades of up to 15 units. In a 76-km² area within the irrigation system, we found an average of close to five ‘connected’ ponds downstream of each irrigated pixel. This high level of connectivity provides opportunities for multiple reuses of water as it flows along toposequences. A fundamental implication is that field ‘losses’ such as seepage and percolation do not necessarily represent losses at a larger scale. Such scale effects need to be adequately taken into account to avoid making wrong assumptions about water-saving interventions in irrigation.     

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.     

Linking water market functioning, access to water resources and farm production strategies: example from Pakistan

As a response to inadequacy in canal water supplies, farmers in Pakistan have invested in private tubewells to control irrigation water resources. Also, they participate in surface water and groundwater markets that take place within tertiary units of the irrigation system.The present paper describes the functioning and organization of these water markets, using information collected in sample watercourses of the Fordwah Branch irrigation system, South-Punjab, Pakistan. The variability in type and intensity of water markets is investigated with regard to access to water resources and farm production strategies and constraints.     

Assessment of irrigation and environmental quality at the hydrological basin level: I. Irrigation quality

Irrigated agriculture notably increases crop productivity, but consumes high volumes of water and may induce off-site pollution of receiving water bodies. The objectives of this paper were to diagnose the quality of irrigation and to prescribe recommendations aimed at improving irrigation management and reducing the off-site pollution from a 15,500 ha irrigation district located in the Ebro River Basin (Spain). Three hydrological basins were selected within the district where the main inputs (irrigation, precipitation, and groundwater inflows) and outputs (actual crop's evapotranspiration, surface drainage outflows, and groundwater outflows) of water were measured or estimated during a hydrological year. The highest volume of water (I = 1400 mm/year) was applied in the basin with highly permeable, low water retention, flood irrigated soils where 81% of the total surface was planted with alfalfa and corn. This basin had the lowest consumptive water use efficiency (CWUE = 45%), the highest water deficit (WD = 5%) and the highest drainage fraction (DF = 57%). In contrast, the lowest I (950 mm/year), the highest CWUE (62%), and the lowest WD (2%) and DF (37%) were obtained in the basin with 60% of the surface covered with deep, high water retention, alluvial valley soils, where 39% of the cultivated surface is sprinkler irrigated and with only 48% of the surface planted with alfalfa and corn. We concluded that the three most important variables determining the quality of irrigation and the volume of irrigation return flows in the studied basins were (i) soil characteristics, (ii) irrigation management and irrigation system, and (iii) crop water requirements. Therefore, the critical recommendations for improving the quality of irrigation are to (i) increase the efficiency of flood-irrigation, (ii) change to pressurized systems in the shallow and highly permeable soils, and (iii) reuse of drainage water for irrigation within the district. These management strategies will conserve water of high quality in the main reservoir and will decrease the crop water deficits and the volume of irrigation return flows, therefore, minimizing the off-site pollution from this irrigation district.     

Agro-hydrological evaluation of on-farm rainwater storage systems for supplemental irrigation in Laikipia district,Kenya

Semi-arid agro-ecosystems are characterized by erratic rainfall and high evaporation rates leading to unreliable agricultural production. Total seasonal rainfall may be enough to sustain crop production, but its distribution and occurrence of intra-season dry spells (ISDS) and off-season dry spells (ODS) affect crop production. Rainwater harvesting (RWH) and management, especially on-farm storage ponds for supplemental irrigation offers an opportunity to mitigate the recurrent dry spells. Farm ponds are small runoff storage structures of capacities ranging from 30 to 100 m³ used mainly for supplemental irrigation of kitchen gardens, and sometimes for domestic and livestock water supply. The main objective of the study was to evaluate the hydrological and economic performance of farm ponds with the view of assessing their contributions to water and food security in semi-arid agro-systems of Kenya. Agro-hydrological evaluation of on-farm runoff storage systems entailed field survey, monitoring of water losses, analysis of rainy seasons and dry spell occurrence, soil moisture and water balance, estimation of supplemental irrigation requirement (SIR) and farm-level cost-benefit analysis of cabbage production using low-head drip irrigation system. Significant water losses through seepage and evaporation, which accounted on average for 30–50% of the stored runoff, is one of the factors that affect the adoption and up-scaling of on-farm water storage systems. Frequency analysis of rainfall revealed that there is 80% probability of occurrence of dry spells exceeding 10 and 12 days during the long rains and short rains, respectively. The occurrence of off-season (after rainfall cessation) dry spells was more pronounced than intra-seasonal (within the rainy season) dry spells. The length of intra-seasonal (10–15 days) was less than off-season dry spells (20–30 days). The occurrence of off-season dry spells coincides with the critical crop growth stage, in particular flowering and yield formation stages. A 50 m³ farm pond with a drip system irrigation system was found adequate to meet supplemental irrigation requirement for a kitchen garden of 300–600 m² planted with a 90 days growing period cabbages. The cost-benefit analysis showed that farm ponds are feasible solutions to persistent crop failures in semi-arid areas which dominant most countries in Sub-Saharan Africa (SSA).     

大型水稻灌区高产节水灌溉优化配水模型研究

根据江苏省北部地区水资源供需矛盾突出的现状,以大型水稻灌区为研究对象,研究水资源的优化分配问题,从水稻水分生产函数和作物需水模型入手,建立了外引河湖水、内提回归水两种水源供水条件下的水稻全生育期适时调度优化配水数学模型。以灌区典型年供水资料,对优化配水模型进行了复核验证。所建立的模型,与灌区实际用水条件基本相符,为水稻灌区用水管理提供了一条新路。     

Simulation of automatic control of an irrigation canal

Improved water management and efficient investment in the modernization of irrigation schemes are essential measures in many countries to satisfy the increasing demand for water. Automatic control of the main canals is one method for increasing the efficiency and flexibility of irrigation systems. In 2005, one canal in the irrigation scheme ‘Sector B-XII del Bajo Guadalquivir’ was monitored. This canal is representative of irrigation schemes in Southern Spain; it is divided into four pools and supplies an area of 5154 ha. Ultrasonic sensors and pressure transducers were used to record the gate opening and water levels at the upstream and downstream ends of each canal pool. Using the recorded data and the SIC (Simulation of Irrigation Canals) hydraulic model, two canal control options (local upstream control and distant downstream control) were evaluated using a PI (Proportional-Integral) control algorithm. First, the SIC model was calibrated and validated under steady-state conditions. Then the proportional and integral gains of the PI algorithm were calibrated. The controllers were tested using theoretical demand changes (constant outflow followed by a sudden demand increase or decrease) and real demand changes generated on the basis of a spatially distributed crop water balance that included a number of sources of variability (random and not random) in the determination of field irrigation timing and depth. The results obtained show that only the distant downstream controller was able to adjust quickly and automatically the canal dynamics to the varying water demands; it achieved this efficiently and with few spills at the canal tail, even when there were sudden and significant flow variations.     

An integrated hydro-economic modelling framework to evaluate water allocation strategies II: Scenario assessment

In this paper the results of an assessment of the hydrological and economic implications of reallocating water in the Musi sub-basin, a catchment within the Krishna Basin in India, are reported. Policy makers identified a number of different but plausible scenarios that could apply in the sub-basin, involving; supplying additional urban demand from agricultural allocations of water, implementing a number of demand management strategies, changing the timing of releases for hydropower generation, changing the crops grown under irrigation, reducing existing stream flows and allowing for more environmental flows. The framework chosen to undertake this assessment was a simulation model that measures and compares the economic values of water allocation scenarios determined from a water allocation model that accounts for supplies of groundwater and surface water across a number of regions and over a variety of uses. Policy makers are provided with the range of measures on the security of the supply of water and the social costs and benefits of reallocating water between sectors and across regions within the sub-basin. Taking water from agriculture to supply urban users has a greater impact on irrigation supplies during dry years. It was also found that changing the allocation of water between sectors, by taking it away from agriculture had a large positive economic impact on the urban sector. Yet the costs involved in undertaking such a strategy results in a significant loss in the net present value of the scheme. Stream flow reductions, if significantly large (at around 20%), were found to have a large physical and economic impact on the agricultural sector. Implementing water saving strategies in Hyderabad was found to be more cost effective than taking water from agriculture, if rainwater tanks are used to achieve this. Changing the timing of hydropower flows resulted in best meeting of irrigation demand in NSLC and NSRC. Under this scenario, the crops grown under irrigation were found to have a significant economic impact on the sub-basin, but not as large as farmers undertaking crop diversification strategies, ones which result in farmers growing less rice. The security of supplying water to different agricultural zones has significantly improved under this scenario. Finally, releasing water for environmental purposes was found to have only a minor impact on the agricultural sector.     

Optimal irrigation planning model for an existing storage based irrigation system in India

A weekly irrigation planning LP model is formulated for determining the optimal cropping pattern and reservoir water allocation for an existing storage based irrigation system in India. Objective of the model is maximization of net annual benefit from the project. In an irrigation planning of a storage based irrigation system, initial storage of the reservoir at the beginning of the reservoir operation, expected inflows into the reservoir during each intraseasonal period, capacity of channels, crop calendar and yield response to water deficit in each growth stage of crop play a vital role in deciding acreage and water allocation to each crop. The planning model takes into account yield response to water deficit in each intraseasonal period of the crop, expected weekly inflows entering into the reservoir, storage continuity of reservoir, land and water availability, equity of water allocation among sub areas and proportionate downstream river release. One year comprising of 52 weeks is considered as planning horizon. To account for uncertainty in water resources availability, the model is solved for four levels of reliability of weekly inflows entering into the reservoir (90%, 85%, 80% and 75%). Alternative optimal cropping patterns and weekly releases to crops grown in each sub area under each main canal are obtained for various states of initial storage at the beginning of reservoir operation and for various levels of weekly inflows into the reservoir. Results reveal the importance of initial state of reservoir storage for feasible solution and shows the impact on cropping pattern with the change in initial storage of reservoir for different levels of reliability of weekly inflows.     

Irrigation modernization and water conservation in Spain: The case of Riegos del Alto Aragón

This study analyzes the effects of irrigation modernization on water conservation, using the Riegos del Alto Aragón (RAA) irrigation project (NE Spain, 123354 ha) as a case study. A conceptual approach, based on water accounting and water productivity, has been used. Traditional surface irrigation systems and modern sprinkler systems currently occupy 73% and 27% of the irrigated area, respectively. Virtually all the irrigated area is devoted to field crops. Nowadays, farmers are investing on irrigation modernization by switching from surface to sprinkler irrigation because of the lack of labour and the reduction of net incomes as a consequence of reduction in European subsidies, among other factors. At the RAA project, modern sprinkler systems present higher crop yields and more intense cropping patterns than traditional surface irrigation systems. Crop evapotranspiration and non-beneficial evapotranspiration (mainly wind drift and evaporation loses, WDEL) per unit area are higher in sprinkler irrigated than in surface irrigated areas. Our results indicate that irrigation modernization will increase water depletion and water use. Farmers will achieve higher productivity and better working conditions. Likewise, the expected decreases in RAA irrigation return flows will lead to improvements in the quality of the receiving water bodies. However, water productivity computed over water depletion will not vary with irrigation modernization due to the typical linear relationship between yield and evapotranspiration and to the effect of WDEL on the regional water balance. Future variations in crop and energy prices might change the conclusions on economic productivity.     

Proceedings of the Sixth International Conference on Precision Agriculture and Other Precision Resources Managemen on CD-ROM | Robert,P.C. et al., (Ed.), American Society of Agronomy/Crop Science Society of America/Soil Science Society of America,Madison, WI, 2003, USA, 2095 pp. Price: US$14.00.CD-ROM

The objective of this paper is to examine the impacts of terminating rice [Oryza sativa] irrigation earlier than usual. One straightforward result of this would be the associated cost savings (≈$10 ha⁻¹ per irrigation or more with deep wells) without placing a value on the water itself. However, another option exists for some farms. An assumption is that the typical farm will be constrained from irrigating all of the soybean [Glycine max (L.) Merr] crop due to constraints in any or all of water supply, pumping capacity, and labor availability. In these cases, a portion of the land in soybean production would be non-irrigated for the first part of the growing season. This study explores the possibility of transferring irrigation water to the soybean crop after the needs of the rice crop are met. If rice and soybean planting dates are planned optimally, this partial irrigation can lead to substantial soybean yield improvements and therefore a more profitable rice/soybean production system. On average, across a 41 year period, net revenue gains from partially irrigating the soybean crop were consistently positive, ranging from $41 to $458 ha⁻¹. While these numbers are interesting, the reader is cautioned that the results are based on simulation models and therefore the marginal analysis results are more realistic. On clayey and silt loam soils at Keiser and Stuttgart, respectively, the change in returns for moving from the least to the most water saving rice irrigation strategy was $190 and $99 ha⁻¹, respectively. In addition, for any given year, financial losses are typically restricted to the irrigation setup costs of $17 ha⁻¹. The irrigation termination strategies therefore show high economic potential with little risk of loss.     

Irrigation water distribution and long-term effects on crop and environment

The response of three water delivery schedules, representing various levels of flexibility, on crop production, water saving, soil salinization, drainage volumes and watertable behavior was examined. A physical-based transient soil water and solute transfer model, Soil–Water–Atmosphere–Plant (SWAP), was used as a tool. The evaluations were made for un-restricted and restricted water supply situations considering three different watertable conditions prevailing in the fourth drainage project (FDP) of the Punjab, Pakistan. From the simulation results it is apparent that on average the effect of irrigation schedule flexibility on crop yields is not very significant. However, compared to a fixed schedule provided un-restricted canal water supplies are available, the productivity of irrigation water supply (Y_act/I_rr), is up to 30% higher for the on-demand schedule. The on-demand schedule capable of complying with the temporal variations in climate is also more effective in water saving, reducing drainage volumes and controlling rising watertables if farmers follow guidelines and do not over-irrigate. In the present water deficient environment of the Indus basin, the benefits of the on-demand schedule and a fixed schedule are comparable. In the absence of sufficient canal water supplies, infrastructure and a well-designed and effective monitoring and communication system, moving towards the on-demand system will be un-productive. For the long-term sustainability of the irrigation system, improvements in the performance of the present water allocations and on-farm water management practices seems to be more necessary.     

Water conservation practices for a river valley irrigated with groundwater

Water conservation strategies for center pivot and furrow irrigation in the Central Platte Valley of Nebraska were evaluated using computer simulation. Irrigation requirements, grain yield, return flow and net depletion (gross irrigation minus return flow) of groundwater were simulated for a period of 29 years for Hord and Wood River silt loam soils. Grain yields were simulated for a typical corn variety for non-limiting water supplies (maximum attainable yield), for two levels of deficit irrigation (irrigation limited to certain growing periods), and for dryland conditions. Additional simulations were performed for a short-season corn, grain sorghum, and soybeans. The impacts of tillage practices on water conservation were also investigated.Center pivot irrigation on the Hord silt loam required 75–125 mm/year less water application than furrow irrigation. For the Wood River silt loam, water applications were the same for both irrigation systems. Applied water depths were reduced by an additional 75–125 mm using deficit irrigation with only a small reduction in yield. Return flow to the groundwater was small for well-managed pivots but high for some furrow irrigation systems based on the assumption that all deep percolation returns to the aquifer in the Central Platte Valley. Net depletion (gross irrigation minus return flow) of the groundwater for a center pivot with LEPA was 50 mm (17%) less than a center pivot with impact sprinklers. Ridge till had a net depletion 50 mm (25%) less than conventional tillage (double disk, plant) for furrow systems.     

Multiple-Use Management in a Large Irrigation System: Benefits of Distributed Secondary Storage

Large-scale canal irrigation projects are commonly seen as profligate users of water. Their low water productivity has been attributed by many authors to deficiencies in management or to actions by farmers to circumvent management control over water distribution. Inadequate design has sometimes been cited as a contributing factor, but the relationship between design and manageability has received too little attention. In most conventional large-scale irrigation systems imperfect matching between water supply and demand is an inescapable fact of life that leads to operational spillages and low efficiency. Provision of auxiliary storage reservoirs at strategic points within the canal system can buffer this mismatch and improve service delivery and also aid recovery of return flows. Such reservoirs may bring additional benefits in that they provide opportunities for multiple-use management and increased productivity of irrigation water. This paper presents a case study of Mahaweli System H in Sri Lanka, which incorporates a large number of secondary reservoirs within its 25000 ha command area. The paper examines current operational performance and considers scope for and constraints to multiple-use management.     

Integrated decision making for reservoir,irrigation, and crop management

An integrated approach to reservoir, irrigation, and cropping management which links four different models—a hydrologic model (PRMS), a crop growth simulation model (EPIC), an economic model based on linear programming, and a dynamic programming model—is developed and demonstrated. The demonstration is based on an irrigation district located in a subhumid climate with an irrigation reservoir large enough for over-year storage. The model is used to make repeated simulations for various planning horizons. Two different types of results are presented. The first provides the probability that each of the various farm plans (land/crop/water allocation) will be chosen as the optimum in the first year of the planning horizon. The second approach provides probability distributions of accumulated revenues over a chosen length of planning horizon. Each distribution is associated with an initial reservoir level and a particular farm plan in the first year of the planning horizon. The consequence of selecting certain farm plans at the beginning of a specified planning horizon is therefore quantified in a probabilistic way. Based on families of probability–revenue curves, an irrigation manager can simultaneously evaluate crop, irrigation, and reservoir management options.     

Irrigation water management for crop diversification: Application of the WACCROD model

The actual water management practices, in terms of the volumes and intervals of delivery, are examined in a rice-based irrigation subsystem where crop diversification is practised. A simulation model (WACCROD) is used to generate the hypothetical water requirements of the changing crop mixture at quartenary and tertiary levels.Crops other than rice were planted in the dry season to reduce the need for water. Then, as the available water supplies diminished, the volume and timing of water deliveries changed based on the time, hydraulic location and relative importance of the crop.     

Economic impacts on farm households due to water reallocation in China's Chaobai watershed

Our study area in the Chaobai watershed, upstream of Miyun Reservoir, has been undergoing agricultural water transfers to downstream municipal uses in Beijing. We examine the impacts of water reallocation on crop production and farmers’ income and discuss issues relating to current compensation mechanisms. We use data from a survey of 349 farm households and their farm plots in the upper Chaobai watershed within Hebei province. Water reallocation from upstream to downstream areas has reduced agricultural water supply and the area irrigated. Regression results show that in plots deprived of irrigation, maize yields decrease by 21% and crop revenues decline by 32%. On average, losing irrigation on one hectare of cultivated land reduces net crop income by 2422 yuan. We examine compensation arrangements and social equity for the major policies implemented in the region and we identify gaps between current compensation levels and farmers’ income and production losses. The current compensation received by farmers is generally lower than the losses incurred due to reduced irrigation. A more appropriate compensation mechanism is called for in future water transfers.     

Characterising rice-based farming systems to identify opportunities for adopting water efficient cultivation methods in Tamil Nadu, India

Efficient water use in rice cultivation is a prerequisite for sustaining food security for the rice consuming population of India. Novel rice production practices, including water-saving techniques, modifications in transplanting, spacing, weeding and nutrient management, have been developed and shown to be effective on farm, but adoption of these techniques by farmers has remained restricted. Potential constraints include technical difficulties with new practices, and labour and gender issues which differ between farms. On the basis of a rapid survey of 100 rice-based farms, four farm types were identified based on their socio-economic and biophysical characteristics. Detailed farm surveys were conducted on three representative farms of each farm type to evaluate land use patterns, use of inputs such as water, labour, nutrient, capital and machinery, income from crop and animal production and off-farm activities. Opportunities exist for one or more new rice cultivation techniques to be adopted in all the four farm types. For all farm types, however, the opportunities for use of water-saving irrigation were the least promising. In general, adoption of water-saving irrigation will not improve farmers’ livelihoods despite its importance in reducing water scarcity problems at regional scale. At farm scale, the potential for adoption of water-saving irrigation depends on the season, location of fields and the irrigation source. Changes in government policies such as rules and regulations, pricing, institution building and infrastructure development, as well as training and education of farmers are needed to improve the adoption of modified methods for rice cultivation.     

基于改进多目标决策模型的大桥水库灌区渠系自适应规划方法

提出基于改进多目标决策模型的大桥水库灌区渠系自适应规划方法,合理规划大桥水库灌区渠系配水,提高水资源利用率,降低无效弃水以及对生态环境的影响。以配水结束后灌区各渠系缺水量、渠道输水损失量以及农作物生产带来的灰水足迹三者最小为大桥水库灌区渠系规划多目标决策函数,以渠道输水能力、水量和时间为约束条件,构建大桥水库灌区渠系规划的多目标决策模型;以栅格法构建路径规划的运行环境,通过移动几率优化、信息素挥发系数自适应调整两方面改进蚁群算法,通过改进蚁群算法寻优获取渠道缺水量、输水损失量、灰水足迹最小的水库灌区渠系规划结果。实验证明：该方法可以有效规划大桥水库灌区渠系的水资源,规划后的灌区渠系在缺水量、渠道输水损失量以及灰水足迹方面都有较好的表现,且效率高、应用性强。     

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.