Performance assessment of Doroodzan irrigation network by steady state hydraulic modeling

There is a need for improvement in the operation and management of many irrigation and drainage systems worldwide. Computer models are used widely for better management. One of such models is HEC-RAS that was applied to Ordibehesht Canal at the Doroodzan irrigation network, northwest of Fars province in the southern Iran. The model was calibrated and validated for two irrigation seasons during 2001 and 2002. The present gate opening rules used to control the offtakes were simulated by the model and the discharge reductions were evaluated. Discharge reduction of offtakes due to discharge reductions at system source were evaluated by the model. Results show that the present rule is not appropriate for the present system. Fluctuations of discharge at the beginning of canal show considerable and nonuniform changes in discharge of offtakes along the Ordibehesht Canal. The head offtakes show more reductions in the water delivered than middle and tail offtakes. A new sensitivity indicator was defined and used to show the response of offtakes due to discharge changes at system source. The study also shows that HEC-RAS model can be used successfully for a large and complex irrigation system for evaluation of its performance in the absence of observed flow data and improvement of irrigation management plans.     

Evaluation of partial root-zone drying for potential field use as a deficit irrigation technique in commercial vineyards according to two different pipeline layouts

The use of partial root-drying (PRD) irrigation implies doubling pipelines instead of using a conventional single pipeline. However, pipelines can be spaced a short distance apart (e.g. 1 m) along the vine row (“D” layout) or joined with cable ties and laid as a single pipeline (“S” layout). Pipelines in “S” configuration are laid under the vine row, and in “D” at both sides of the vine row. These two different layouts can change the wetted soil zone and affect grapevine response to irrigation. The focus of this study was therefore on establishing the role of pipeline layout in vine-grape (cv. ‘Tempranillo’) response under semi-arid conditions in which PRD is managed as a deficit irrigation technique. Six irrigation treatments were applied, which resulted from the combination of Control (C, full irrigation), PRD and seasonal sustained deficit irrigation (SSDI), and “S” and “D” pipeline layouts. SSDI and PRD were irrigated to 50% C throughout the irrigation season, and C irrigation was scheduled according to a crop water balance technique. Midday stem water potential (Ψ_stem) and leaf conductance (g_l) indicated that, on the whole, PRD treatments had a slightly higher water status than SSDI treatments, but a substantially lower status than C treatments. Use of the “D” pipeline layout significantly reduced Ψ_stem in both PRD and SSDI treatments and in some instances for Control conditions, too. Berry yield, vine intercepted radiation, leaf abscisic acid (ABA) and g_l were highly correlated with Ψ_stem. Differences in water status between PRD-S and SSDI-S, according to a sub-surface irrigation test, seemed to be more related to changes in soil evaporation losses and irrigation efficiency than to any intrinsic PRD effect. PRD-S accounted for water savings equivalent to 10% according to the ratio between applied water and grape production for the SSDI-S treatment, whereas PRD-D berry yield was not significantly different from that associated with the SSDI-S treatment. In conclusion, under the growing conditions of this experiment, PRD-S offered the possibility of slightly improving water conservation when irrigation was applied to the soil surface.     

Evaluation of plant-based water status indicators in mature apple trees under field conditions

The performance of different indicators of plant water status as a tool for irrigation management was evaluated in mature field grown ‘Golden Delicious’ apple trees during the late summer of 1998. Control (C) and stress (S) treatments were studied. In the C treatment trees were irrigated daily at 100% ET_c whereas in the S treatment water was withheld during 31 days (DOY’s 236–266). Predawn water potential (Ψ_pd) and midday stem water potential (Ψ_stem) were measured several times a week during the experimental period. Three daily measurements of stomatal conductance (g_s) and stem water potential were made during five consecutive days in mid-September. Trunk diameter changes (TDC) were recorded by LVDT sensors, and from these measurements, maximum daily shrinkage (MDS), daily growth (DG), and cumulative growth (CG) were calculated. Midday Ψ_stem showed the best ratio between the response to moderate water stress and tree variability (“signal/noise” ratio) among the indicators studied here, followed closely by Ψ_pd. On the other hand, the poorest water status indicator was g_s. Due to the low trunk growth rate of the trees, and its high variability, DG and CG were not adequate indicators. MDS showed a lower sensitivity to water stress and a higher variability (CV = 0.19) than midday Ψ_stem (CV = 0.08) and Ψ_pd (CV = 0.10). However, MDS correlated well with ET₀ and with midday Ψ_stem (R ² = 0.79) thus, making this parameter an interesting and promising tool for irrigation management in apple orchards. More research needs to be done in order to define reference values for MDS and plant water potential indicators, in relation to evaporative conditions and in different phenological periods, and to quantify the relationship between water status indicators values and apple tree yield and fruit quality.     

Use of stem diameter variations to detect plant water stress in tomato

The sensitivity of stem diameter variations (SDV) measured with linear variable transducer (LVDT) sensors as indicators of plant water status in tomato was evaluated. Two tomato crops were grown sequentially in a sandy loam soil in an unheated plastic greenhouse. These were an autumn–winter tomato crop (autumn crop) and a spring–summer tomato crop (spring crop). One drying cycle of 61 days was imposed to the autumn crop in winter at 92 days after transplanting (DAT). Two drying cycles, each of 29 days, were applied to the spring crop, to young (58 DAT) and mature plants (121 DAT). For each drying cycle, four replicate plots did not receive irrigation, and four were well watered. During each drying cycle, LVDT sensors continuously measured SDV, and daily measurements were made of leaf (Ψ _leaf) and stem water potential (Ψ _stem). SDV data was interpreted using the SDV-derived indices, maximum daily shrinkage (MDS) and stem growth rate (SGR). The response of SDV-derived indices to water deficit differed with (1) climatic conditions during stress imposition and (2) crop age. In the winter drying cycle of the autumn crop, the responses of the SDV-derived indices to soil drying were relatively small and slower than Ψ _leaf and Ψ _stem. Under warmer conditions, the SDV-derived indices were much more responsive to soil drying. In rapidly growing young plants, where SDV was characterized by high SGR and small MDS, SGR was the most sensitive SDV-derived index. In more mature plants with little stem growth, MDS was the most sensitive SDV-derived index. In mature plants grown in warm to hot conditions, MDS (1) responded at a similar time or earlier than Ψ _leaf and Ψ _stem and (2) had larger “signal” values (ratio of values from unwatered to control plants) than Ψ _leaf and Ψ _stem. However, there was appreciably more “noise” (coefficient of variation, CV) associated with the SDV-derived indices, giving lower “sensitivity” values, determined from “signal” to “noise” ratios, than for Ψ _leaf and Ψ _stem. Regression analysis between MDS of well-watered plants and climatic variables gave best results for a linear relationship between MDS and daily maximum vapor pressure deficit. There were strong linear relationships between MDS and Ψ _leaf for each drying cycle. The slopes of these relationships differed with crop age indicating that there was no constant relationship between MDS and Ψ _leaf for a whole season. Overall these results demonstrated that MDS and SGR can be sensitive indicators of the water status of tomato crops under conditions of moderate to high evaporative demand. However, the variability associated with the SDV-derived indices and the changing MDS–Ψ _leaf relationship with crop age represent major issues regarding the development of irrigation scheduling protocols for tomato.     

Water, nitrogen and yield losses for a nonhomogeneous furrow set

Water distribution can be nonuniform along the furrow length under surface irrigation. This “down field” nonuniformity is combined with “inter-row” non-uniformity which is a consequence of differences in infiltration characteristics across the plot. Global nonuniformity of application depth causes variation of yield, drainage and nitrogen leaching. In addition to that, due to year-to-year variability of climate, irrigation depths range significantly (from 0 to 360 mm/season). The objective of this paper is to study the impact of the nonuniformity of irrigation-water distribution within a furrow plot on yield, water and nitrogen losses when climate variation is taken into account. Six maize vegetation seasons on a Chromic Luvisol soil in the Sofia region with varying irrigation requirements are considered. Irrigation water is distributed in relative terms over the plot at different levels of nonuniformity (coefficient of variation C_v ranging from 13 to 66%) by the FURMOD model. Water and nitrogen cycle and crop growth are simulated then compared at 30 representative points in the set with various “climate-irrigation nonuniformity” combinations by the CERES-maize model. It was established that non-uniformity of irrigation is not important in wet vegetation periods. The drier the irrigation season, the higher the yield loss and risk to environment due to nonuniformity of irrigation water distribution. In moderate and dry irrigation seasons it causes yield losses of 2–14%, significant variation (30% < C_v < 200%) of drainage, nitrogen leaching and residual soil nitrate over the furrow set. Surface irrigation performances can be improved by reducing lateral nonuniformity of stream advance.     

Application of a hydraulic model for testing management decisions at distributary level

Summary This study was conducted on the Lagar Distributary of Gugera Branch of Lower Chenab Canal, Punjab, Pakistan. A computer model MISTRAL was adopted for evaluating management options. The study showed that the model can be used as a decision support tool for prioritizing management options. The model suggests that under current physical conditions of this distributary the combination of rotation between the distributaries and along the distributary canals can improve the equity of water discharge. For example, in case of Lagar Distributary the discharge of tail outlets can be increased threefold by introducing rotation between the tail of the distributary and an offtaking minor canal. A small decrease in the discharge of the minor would result from adopting this option. A combination of rotations between this and neighboring distributaries and along the Lagar itself can increase the discharge of tail outlets up to seven times. The results of the model indicate that operational changes can improve the discharge of tail outlets to some extent, but the improvement of physical conditions of the distributary is needed to achieve equity conditions, as specified in the design.     

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.     

Effects of alternative water distribution rules on irrigation system performance: a simulation analysis

Based on a simulation model reflecting physical and economic conditions typically found in rice irrigation systems in Asia, the irrigation performance implications of alternative water distribution rules for dry season irrigation are evaluated under varying degrees of water shortage. The rules examined reflect differing water distribution strategies designed either to maximize conveyance efficiency, economic efficiency, or equity; or to achieve a balance between efficiency and equity objectives. Irrigation performance is evaluated using several efficiency measures reflecting the physical, agronomic and economic productivity of water, and one measure of equity. Economic efficiency and equity among farmers within the portion of the irrigation system that is on in any given season are shown to be complementary, and not competing objectives. Economic efficiency and equity among all farmers within the command area of the irrigation system are largely complementary strategies at the lower levels of water shortage, but with increasing shortage, significant tradeoffs develop between these objectives. An operational rule for water distribution under a goal of maximizing economic efficiency is developed, and the data requirements for its implementation are shown to be modest. Under the model's assumed conditions of dry season rice production dependent solely on surface irrigation for water, the distribution strategy designed to maximize conveyance efficiency results in only modestly lower levels of economic efficiency and equity than could be achieved by the strategy designed to maximize economic efficiency.     

Modeling approach for the assessment of recharge contribution to groundwater from surface irrigation conveyance system

Rice–Wheat rotation system utilizes surface, ground and rain water resources conjunctively. Recent studies have shown increasing contribution of groundwater for crop irrigation. As the system utilizes water pumped from the underlying aquifer and partly seeps back, a cycle of recharge and discharge continues. Sustainability of groundwater system for the on-going drought in the country depends mainly on the recharge of the aquifer. The reported study was, therefore, carried out to measure and assess the recharge contribution of a distributary of canal in Punjab, Pakistan. Assessment of recharge through distributary was carried out using a groundwater flow “MODFLOW” model, which utilized the observed watertable, climatic, crop and soil for a period of about 1 year in addition to hydraulic conductivity, evapotranspiration and aquifer characteristics data. The requisite primary data for “MODFLOW” were collected from field and secondary data from public sector organizations dealing with water. Model calibration involved changing input parameters within reasonable limits until acceptable matches were obtained between the observed and simulated water levels for all observed hydrographs. The external inputs such as, recharge through irrigation, precipitation, stresses due to evaporation, lateral flow and stream were simulated to calculate the monthly water budget of aquifer. As concluded, recharge contribution was 16.5% of the inflow rate of the distributary. Using predicted results of the model a relationship between recharge (R) and discharge (Q) was also developed. Although, the presented results of recharge contribution were limited to one distributary of canal irrigation system, yet the developed methodology can be extended to the other canal systems of the Indus Basin.     

A critical review of the concept of equity to support water allocation at various scales in the Amu Darya basin

Even though ‘equity’ appears to be the major objective on all water management levels, the concept as such and its implication for water management are hardly explored within the professional water debate. Utilizing different arguments from the public sector, management and psychology debates, it is argued that the concept of equity is often undefined and usually ambiguous. The paper goes on to explore aspects of ‘equity’ of water allocation between the different riparian states in the Amu Darya basin and between the different upstream and downstream provinces in Uzbekistan and districts within the Khorezm Province of Uzbekistan.     

Drainage design practices in France

Subsurface drainage annual rate boomed in France in late 70s and reached a steady rate of 130 000 hectares in 1982. As a consequence, better knowledge of drainage requirements, techniques and effects on farm management is requested. Emphasis has been put on preliminary survey planning. First of all extension and location of areas to be drained is determined with the help of farmers and local representatives within so-called “local juries”. Secondly, drainage recommandations are derived using the so-called “soil reference area” method. Drainage criteria and design methods are discussed on the basis of recent field experimental results. Drain spacing computation is related to tail recession stage; soil hydraulic properties are measured in situ using Guyon's pumping test. Subsurface and arterial drainage design rate are related to discharge exceedance duration curves and annual level of protection.     

Irrigation reliability and the productivity of water: A proposed methodology using evapotranspiration mapping

Irrigation is the dominant user of water worldwide, but provision of potable water and water for industry are higher priorities and give higher social and economic returns. Irrigation will continue to lose water to competing sectors and the productivity of irrigation systems (since food demand continues to grow) remains a central issue in water management. Performance assessment of irrigation has traditionally been difficult when based on field measurements of flows, deliveries and depths over large areas. Furthermore, performance measures have shifted from narrow engineering indicators to broader productivity issues of production achieved per unit of water consumed. Remote sensing, applied to the estimation of evapotranspiration (ET) over large areas, provides analysts of irrigation systems with extraordinary new tools for the objective assessment of consumption and production – constituting a quantum leap in the assessment of irrigation system performance. Awareness and utilisation of these tools is spreading, but important areas remain to be “converted” from traditional approaches that rely on an array of estimated parameters. The next challenge for remote sensing will be to map the frontier between the reliability of the irrigation service and the productivity achieved. Reliability provides the inducement for farmers to invest in higher productivity – to the benefit of themselves and society – and understanding better how the individual maximises profits within an uncertain irrigation environment can provide important guidance to managers and system designers.     

Flexibility analysis of irrigation outlet structures using simulation of irrigation canal hydrodynamic model

The Upper Swat Canal (USC) System became operational in 1917–1918 in North West Frontier Province (NWFP) of Pakistan. The rehabilitation and modernization of the USC was undertaken with a view to overcoming the shortage of water supplies for irrigation. The water allowance was enhanced from 0.39 to 0.77 Ls⁻¹ ha⁻¹ in the study area. Recently, the operation and management of a secondary canal or ‘distributary’ was transferred to the Farmers Organization (FO). This distributary named ‘Chowki’ offtakes from the Maira Branch of the USC. The cultivable command area (CCA) of this distributary is 4,306 ha and it serves 1,485 beneficiaries. A management committee on Chowki Distributary was formed in 2003. This distributary consists of one main and two minor channels having twenty-eight direct outlets. The Simulation of Irrigation Canal (SIC) hydrodynamic model was used to evaluate the flexibility of Chowki Distributary. The model was calibrated at 100, 80 and 70% of the design discharge (Q _d) and it was validated at 90, 85 and 60% of the design discharge. The observed and simulated water levels were in close agreement with each other for the calibration and validation periods. The statistical analysis and paired t-test indicate that the model results are not statistically different from the measured values at 1% significance level. The simulated results of the SIC model were applied to studying flexibility of the outlet structures along the Chowki Distributary. The flexibility analysis demonstrates that poor performance is inbuilt into the system due to inadequate control over the accuracy of the crest setting during the construction of the outlets.     

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.     

Water integration by plants root under non-uniform soil salinity

Soil salinity over root zone usually demonstrates temporal and spatial variations. By changing irrigation management practices it is possible to change both the frequency of salinity fluctuations and its distribution over the root zone. The objective of this study was to experimentally investigate how plants integrate soil salinity over its rooting depth when irrigated with saline water. Consequently, detailed experiments with alfalfa were conducted in some lysimeters containing packed loamy sand soil. The target soil salinities were created by changing quantity and quality of applied saline water. Results indicated that the uptake rate preliminary reacts to soil salinity. But at given water content and salinity, the “evaporative demand” and “root activity” become more important to control the uptake pattern. The obtained results also indicate that root activity is inconstant during the stress period. By increasing salinity, the activity of that part of the root system is also increased. Thus, most water is taken from the less saline part and the uptake at other parts with higher salinities never stops. Consequently, the reduced uptake in one compartment resulting from high salinity is not only compensated from other parts with less salinities, but also from the same increment by increasing root activity.     

Role of Groundwater in Irrigation Water Management in the Downstream Part of the Yellow River

Water scarcity in the Bojili irrigation District, which is located in the Shandong province in China, affects the management of the irrigation system and has led to the development of water storage functions inside the system. In particular, the irrigation and drainage scheme is used for short-term water storage whereas groundwater is used for long-term storage which is replenished during the monsoon season and drawn from when crop water requirements are not satisfied by surface irrigation.In this paper the storage functions are quantified. The role of groundwater, in relation to rainfall and irrigation depths, is analysed in detail. This analysis, which was carried out at the district and at sub-system scales, is based on data collected from fifty five observation wells between 1991 and 1996 at a 10-day time intervals. The sub-systems, called “divisions”, represent the areas for which irrigation-related information is available.Rainfall, groundwater levels and irrigation data are consistent. They demonstrate the inequity of water allocation between upstream and downstream water users. Accordingly strategies for water management differ between these users. These strategies only partially compensate the effects of scarcity demonstrated by decreasing cropping intensities from upstream to downstream parts of the District.     

下级渠道流量不等时渠系优化配水模型与算法研究

目前国内外现有的渠道优化配水模型,都是在下级渠道配水流量相等这一假定条件的基础上建立的,这与绝大多数渠系实际配水要求不相符合。针对这一问题,建立了下级渠道引水流量不等情况下的渠道优化配水模型,研究了模型的遗传算法的编码及适应度设计方法,编制了VC程序,并用于冯家山灌区北干十一支共24条斗渠道的实际配水过程中进行了对比验证。结果表明,渠系优化配水过程较原配水过程斗渠配水时间搭配合理、支渠配水流量均匀,符合优化配水原则,渠系渗透损失水量比原方案可减少17.8%。表明模型及其求解算法是可行的,可为下级引水渠道流量不等时的渠系优化配水决策提供理论和技术支持。     

A longitudinal examination of business performance indicators for drought-affected farms

Frequent severe droughts can financially cripple dryland farm businesses and farmers need effective business strategies to survive. This study analysed the economic performance of 123 farms in a rainfed agricultural region of Australia from 2004 to 2009, a period that included severe droughts in 2006 and 2007. The business indicators examined were business equity, operating profit/ha, return on capital, and the debt to income ratio and the droughts altered these indicators for many of the farms surveyed. Over the study period the equity position of just over 60% of farms declined, although 55% of these had more than 80% equity in the business initially and were able to absorb a short term decline in equity caused by the drought. In addition, 9% of farms had levels of equity below 80% at the start of the investigation, but actually improved their equity position by the end of the study. Strong links were found between wheat yield and the business indicators. Mostly this was due to the crop dominant nature of the farm businesses where wheat was by far the main crop. However, farms that were able to capitalise on favourable conditions in other years were better placed to enhance or recover their financial position. Farms that cropped a higher proportion of their farm area were at an advantage. Structural indicators, including the percentage of area cropped, had a small but significant effect on the debt to income ratio, the return on capital and operating profit. Farm diversity also favourably lessened the debt to income ratio. Other factors, including farm size did not influence the outcome of any business indicator. Farms that remained resilient, despite the serious droughts were those that cropped more than 50% of their farm area, were prudent in their expenditure, maintained some enterprise diversity and often generated wheat yields in each year that were near the yield potential for that year.     

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.     

多功能水泵控制阀在水厂的应用

为了解决水厂设计中水泵常见的水锤问题，克服传统的手动闸阀和止回阀诸多不利的缺点，减少故障几率，提高水厂的安全生产可靠性，在沾化水厂二级泵房管道上安装了JD745X型多功能水泵控制阀替换止回阀，原手动控制阀保留并作为检修阀使用。经过多年运行及数据分析，认为此水泵控制阀是一种兼水泵控制、止回、消除水锤三种功能于一体的控制阀门，在解决各种故障问题上，具有良好的运行效果，是水泵压水管阀门的更新换代产品，值得推广应用，具有较广的应用前景。