An integrated water trading-allocation model, applied to a water market in Australia

Temporary water trading is an established and growing phenomenon in the Australian irrigation sector. However, decision support and planning tools that incorporate economic and biophysical factors associated with temporary water trading are lacking. In this paper the integration of an economic trading model with a hydrologic water allocation model is discussed. The integrated model is used to estimate the impacts of temporary water trading and physical water transfers. The model can incorporate economic and biophysical drivers of water trading. The economic model incorporates the key trade drivers of commodity prices, seasonal water allocations and irrigation deliveries. The hydrologic model is based on the Resource Allocation Model (REALM) framework, which facilitates hydrologic network simulation modelling. It incorporates water delivery system properties and operating rules for the main irrigation and urban centres in a study area.The proposed integration method has been applied to a case study area in northern Victoria, Australia. Simulations were conducted for wet and dry spells, a range of commodity prices and different irrigation distribution system configurations. Some example analyses of scenarios incorporating water trading were undertaken. From these analyses potential bottlenecks to trade that constrain the economic benefits from temporary water trading were identified. Furthermore, it was found that in certain areas of the system, trading can make impacts of long drought spells worse for water users, e.g. irrigators. Thus, the integrated model can be used to quantify short-term and long-term third party impacts arising from temporary water trading. These findings also highlight the need to link “paper trades” (estimated by economic models) to physical water transfers (estimated by biophysical models).     

Asset Management for Irrigation Systems – Addressing the Issue of Serviceability

This paper advocates the need for defining criteria for level of service provision for irrigation networks and outlines a proposed Irrigation Serviceability Matrix to be used in the preparation of asset management plans and investment strategies for irrigation infrastructure. The development of the Irrigation Serviceability Matrix is based on experienced gained in the UK by the privatised water industry where the level of service provision to customers has become a key determinant for investment in infrastructure. The paper describes the evolution of this process within the UK water industry and its application to the irrigation sector.     

Application of the Analytic Hierarchy Process to irrigation project improvement: Part I. Impacts of irrigation project internal processes on crop yields

Performance improvement of existing irrigation projects has been a major concern in international irrigation development. Activities for irrigation project improvement usually involve not only infrastructure (hardware) improvement but also changes in management. However, the impact of management improvement on irrigation performance has not been sufficiently verified because, in most cases, (a) irrigation project evaluation is done qualitatively, and (b) management improvement is implemented simultaneously with hardware improvement. Therefore, the impact of management improvement needs to be evaluated quantitatively and separately from hardware. This research attempts to quantify effects of management and hardware improvements on irrigation project performance, using the Analytic Hierarchy Process (AHP). First, an AHP model for irrigation project evaluation was developed by using internal process indicators of the rapid appraisal process. Secondly, the AHP model was applied for scoring 16 irrigation projects dealt with in FAO Water Reports 19. Then, finally, effects of the evaluation factors (e.g. managing entities, hardware, water delivery services) on irrigation project performance were analyzed by changing weights of the evaluation factors and comparing correlations between AHP model scores and crop yields. The research showed the potential and effectiveness of AHP application to irrigation project evaluation. Also, it revealed that the quality of water delivery service had a significant impact on crop production. Analysis through correlation did not imply significant relationships among water delivery services, management and hardware. However, it is inferred from the result that there would be still more room to improve the AHP model toward better evaluation of the irrigation project by adding more internal process indicators to the model.     

基于突变理论的吉林西部灌区地下水环境风险评价

地表水作为灌区的灌溉水源,灌溉回归水补给容易引起土壤的次生盐渍化.选取了自然状态、水环境、土壤环境、社会经济环境这4个评价要素和相应的17个评价因子,构建了吉林西部灌区地下水环境风险指标体系,采用突变理论对其进行了评价.分析结果表明,五家子灌区、大安灌区和松原灌区均属于轻险,风险值分别为0.9206、0.9303、0.9196.吉林西部灌区的地下水环境存在风险.     

Review and quantitative assessment of ex situ household rainwater harvesting systems in Ethiopia

Ex situ household rainwater harvesting (RWH) systems have been introduced at a large scale in Ethiopia to increase the water availability for smallholders through supplementary irrigation. The first objective of this paper is to review the performance of these systems in Ethiopia based on various assessment studies. The second objective is to provide quantitative biophysical and socio-economic analyses of ex situ household RWH systems contributing to the better understanding of their performance and the identification of options to improve their performance. Uptake of RWH systems by smallholders in Ethiopia is limited and the available information suggests that this is associated among others with poor planning and implementation, poorly functioning input and output markets and the lack of farmers’ skills to use these systems effectively. Our quantitative meta-analyses illustrate that water availability of three studied RWH systems is low in relation to crop water needs, particularly for maize. The variation in area that can be irrigated across years exposes users of RWH systems to considerable risks as the availability of irrigation water depends on prevailing rainfall conditions. The area that can be irrigated varies greatly depending on amount and distribution of rainfall, type of RWH system and crop type. The economics of onion (cash crop) are promising only for plastic lined RWH systems, but those for maize are unfavourable independent of the studied RWH systems. Associated labour requirements especially for water lifting and application are high and possibly constraining the sustainable use of RWH systems. The potential of ex situ household RWH systems to increase agricultural production and income is site-specific depending on biophysical, institutional and socio-economic conditions, and depends on household-specific conditions.     

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.     

Management of water consumption in agriculture A model for the economic optimisation of water use: application to a sub-humid area

This paper present a set of solutions for new irrigation transformation in a sub-humid area such as Salvatierra (Alava, Spain). The research is based on the choice of crop rotation (cultivated species and its degree of participation) being able to economically optimise the use of available water for irrigation. Hence, we will be able in helping make decisions to plan, from origin, the transformation of a dry area into an irrigated area. To do this, a model of economic use of water has been used in an area with climatic features very similar to a large part of Europe, representing an interesting scenario compared to the places where the model had not been applied. Crops taking part in this rotation to optimise use of water are mainly vegetables, with high water needs, that coexist together with crops for dryland farming even in conditions of lack of water. Crops for dryland farming allow an interesting diversification of activity as well as an average resource assignment to the farms that make possible to cultivate many farms at a time, which obviously implies socio-economic benefits for the achievements in the zone.     

Epistics: A dynamic model to generate nitrogen fertilisation and irrigation schedules in apple orchards, with special attention to qualitative evaluation of the model

Epistics is a model combining a biophysical and a decisional model designed to generate irrigation and N fertilisation schedules in apple orchards. These techniques were chosen since they are key elements in the management of fruit tree cropping systems. The biophysical model representing water and N dynamics in orchards was based on the water and N dynamics of Stics and was completed using a crop water and N requirement estimation method adapted to orchards. It was linked to an agronomic decision rule in a combined model able to generate N fertilisation and irrigation schedules. The Epistics evaluation process dealt with numerical evaluation of state variables (water and N soil content) and qualitative evaluation of model-generated schedules. The numerical evaluation, which concerned the biophysical model of Epistics, was performed on the basis of (i) soil nitrate and water content at the end of winters 2002 and 2003, and on (ii) nitrate and water dynamics during spring and summer 2003. The mean Root Mean Squared Error (RMSE) between observed and simulated values at the end of winter was 3.3% water per horizon and 56 kg N/ha, which is relatively good owing to the high spatial and temporal variability of soil water and nitrate content. The qualitative evaluation of generated schedules was performed during interviews with farmers. Farmers were asked to evaluate the model with reference to their own practices. A sharp difference between farmers and the model concerned the beginning of the irrigation period. This suggested that the model should take into account the constraints imposed by scab and codling moth control practices and irrigation rounds. The difference between model-generated and farmers’ fertilisation practices suggested that the model may take plot vigour into account in the fertilisation decision rule. Such a study is a first step towards the design of models linking sound agronomic decision rules to crop modelling and representing interactions between practices.     

Using EPIC model to manage irrigated cotton and maize

Simulation models are becoming of interest as a decision support system for management and assessment of crop water use and of crop production. The Environmental Policy Integrated Climate (EPIC) model was used to evaluate its application as a decision support tool for irrigation management of cotton and maize under South Texas conditions. Simulation of the model was performed to determine crop yield, crop water use, and the relationships between the yield and crop water use parameters such as crop evapotranspiration (ETc) and water use efficiency (WUE). We measured actual ETc using a weighing lysimeter and crop yields by field sampling, and then calibrated the model. The measured variables were compared with simulated variables using EPIC. Simulated ETc agreed with the lysimeter, in general, but some simulated ETc were biased compared with measured ETc. EPIC also simulated the variability in crop yields at different irrigation regimes. Furthermore, EPIC was used to simulate yield responses at various irrigation regimes with farm fields’ data. Maize required ∼700 mm of water input and ∼650 mm of ETc to achieve a maximum yield of 8.5 Mg ha⁻¹ while cotton required between 700 and 900 mm of water input and between 650 and 750 mm of ETc to achieve a maximum yield of 2.0-2.5 Mg ha⁻¹. The simulation results demonstrate that the EPIC model can be used as a decision support tool for the crops under full and deficit irrigation conditions in South Texas. EPIC appears to be effective in making long-term and pre-season decisions for irrigation management of crops, while reference ET and phenologically based crop coefficients can be used for in-season irrigation management.     

Reducing poverty in sub-Saharan Africa through investments in water and other priorities

Water resources are essential to human development processes and to achieve the Millennium Development Goals that seek, inter alia, to eradicate extreme poverty and hunger, achieve universal literacy, and ensure environmental sustainability. Expanding irrigation is essential to increase agricultural production, which is needed to achieve economic development and attain food security in much of sub-Saharan Africa. Water resources and irrigated agriculture are not developed to their full potential. Currently less than 4% of renewable water resources in Africa are withdrawn for agriculture. Barriers include the lack of financial and human resources to build irrigation and related rural infrastructure and acquire agricultural technology, and inadequate access to markets. This constrains progress towards poverty reduction. We examine the linkages between agricultural water, education, markets and rural poverty through a review of published studies. We argue that, linking agricultural water, education, and market interventions, which are so often implemented separately, would generate more effective poverty reduction and hunger eradication programs. Investments in agricultural water management and complementary rural infrastructure and related policies are the pathways to break the poverty trap in smallholder African agriculture.     

Understanding and managing groundwater and salinity in a tropical conjunctive water use irrigation district

Agricultural production around the world is increasingly being constrained by hydrological factors—such as over-extraction of groundwater in some locations, rising water tables in others, and worsening groundwater quality in general. One such area is the Lower Burdekin irrigation area in northern tropical Australia, where rising watertable levels and increasing salinity concentrations within alluvial deposits are causing concern. The aim of this study was to improve understanding of the processes driving trends in groundwater quantity and quality in Mona Park, a conjunctive water use irrigation district in the Lower Burdekin. The analysis is intended to enable land and water managers to explore alternative policy and management practices to help support the reversal in current trends, and to improve water table conditions in terms of both water quantity and quality. Key lessons that are applicable to the development of new irrigation schemes in wet-dry tropical regions elsewhere in the world are emphasised.This study demonstrated that simple qualitative methods that link historical developments and observed climatic and hydrological trends can support development of a robust understanding of groundwater behaviour. The results showed that to minimise groundwater accessions in wet-dry tropical regions, a large soil water deficit should be maintained in the unsaturated zone prior to the onset of the wet season to buffer against potentially large wet season recharge events, and that this strategy should be implemented from when irrigation is first commenced. It is very clear that groundwater systems under or down gradient from irrigated areas need to be managed adaptively, such that: (1) timely decisions are made in response to changes in watertable level and groundwater quality; and (2) suitable mechanisms are in place to ensure farmers have the financial incentives and flexibility to respond in the short-term. The work also demonstrated that the establishment of good baseline data prior to irrigation development, and long-term analysis (>30 years) involving various combinations of wet and dry periods, are required in order to build a comprehensive understanding of potential groundwater behaviour and adaptive management needs.     

Faecal contamination and hygiene aspect associated with the use of treated wastewater and canal water for irrigation of potatoes (Solanum tuberosum)

Clean water has become one of the main limiting factors in agricultural food production in Europe, especially for countries around the Mediterranean, who now face more severe and frequent seasonal water shortages. In order to overcome water shortages the European Water Framework Directive encourages and promotes the use of treated urban wastewater in agriculture. However, the use of poor quality water in agriculture poses potential health risks. The application of wastewater through subsurface drip irrigation lines could possibly overcome public health concerns by minimizing contact with wastewater by farmers, farm workers but it is uncertain if the risk for consumers of wastewater irrigated produces would be acceptable. The objective of the current study was therefore to assess whether subsurface irrigation of potatoes with low quality water was associated with higher food safety and reduced human health risks as compared with surface irrigation. The microbial quality of soil and potatoes irrigated by sprinkler, furrow and subsurface drip irrigation, using treated urban wastewater, canal water and tap water were compared at experimental sites near Belgrade, Serbia and in Bologna, Italy. Water, soil and potato samples were collected from March 2007 to September 2008 and their faecal contamination estimated by enumeration of the faecal indicator Escherichia coli. In addition, water and potatoes in Italy were analysed for the presence of helminth eggs, another important indicator of faecal pollution. A quantitative microbial risk assessment (QMRA) model combined with Monte Carlo simulations was used to assess whether the different irrigation practices and associated health risks complied with guidelines set by the World Health Organization (WHO). The study found low levels of E. coli in irrigation water (Italy mean value: 1.7 colony forming units (cfu)/ml and Serbia 11 cfu/ml), as well as in soil (Italy mean: 1.0 cfu/g and Serbia 1.1 cfu/g). Similar low concentrations of E. coli were found on potatoes (Italy mean: 1.0 cfu/g and Serbia 0.0 cfu/g). The vast majority (442/516) of the collected different samples were free of E. coli. No helminth eggs were found in any types of irrigation water or on the surface of potatoes. The risk assessment models found the use of treated wastewater to exceed the levels of risks for gastro-intestinal disease (1.0 × 10⁻³ disease risk) as recommended by the World Health Organization (WHO) for the accidental ingestion of soil by farmers (Serbia: 0.22 and Italy: 5.7 × 10⁻²). However, samples that exceeded disease risks set by the WHO were collected before initiation of wastewater irrigation and were limited to a few numbers of samples, which would indicate environmental contamination not linked to irrigation practice. Disease risk from consumption of potatoes in Italy and in Serbia was found to be within acceptable levels. No relationship was found between E. coli concentrations in irrigation water, soil and produce. Similar lack of association was found for E. coli findings in sprinkler, furrow or subsurface drip irrigated soils and produce. This indicates that subsurface drip irrigation can be practiced while ensuring food safety and protecting the health of consumers and farmers.     

荆州市农村水利基础设施建设融资问题研究

农村水利基础设施建设不仅关系到我国长期粮食安全,更关系到农民增收、农业可持续发展的基础条件。农村水利基础设施是为农业生产、农村经济发展、镇村居民生活创造条件的基础设施。文章首先分析了农村水利基础设施的内涵,然后分析了荆州市农村水利建设融资存在的问题,最后分析了荆州市农村水利基础设施投融资政策及荆州市农村水利基础设施建设投融资模式。     

基于资产管理方法的灌区资产综合评价体系研究

加强灌区建筑物管理是实现灌区可持续发展的有效途径。将商业财务领域中的资产管理方法引入到灌溉系统管理中来,根据其基本原理建立了灌区资产综合评价体系,通过层次分析法和熵值法确定指标权重,对灌区资产的运行状况、水力性能、重要度等类别的不同指标进行综合评价,其评价结果可以作为决策支持信息确定资产更新改造的优先性,制定中长期的投资策略。以湖北省漳河灌区四干渠和二干渠为例,对其干渠沿线资产(水闸、涵管、渡槽、桥梁、泵站等5类)进行评价和对比分析。评价结果与灌区实际运行、管理情况基本一致。     

Management trends and responses to water scarcity in an irrigation scheme of Southern Spain

Improvement of irrigation management in areas subjected to periods of water scarcity requires good knowledge of system performance over long time periods. We have conducted a study aimed at characterizing the behaviour of an irrigated area encompassing over 7000 ha in Southern Spain, since its inception in 1991. Detailed cropping pattern and plot water use records allowed the assessment of irrigation scheme performance using a simulation model that computed maximum irrigation requirements for every plot during the first 15 years of system operations. The ratio of irrigation water used to maximum irrigation requirements (Annual Relative Irrigation Supply, ARIS) was well below 1 and oscillated around 0.6 in the 12 years that there were no water supply restrictions in the district. The ARIS values varied among crops, however, from values between 0.2 and 0.3 for sunflower and wheat, to values approaching 1 for cotton and sugar beet. Farmer interviews revealed some of the causes for the low irrigation water usage which were mainly associated with the attempt to balance profitability and stability, and with the lack of incentives to achieve maximum yields in crops subsidized by the Common Agricultural Policy (CAP) of the European Union. The response to water scarcity was also documented through interviews and demonstrated that the change in crop choice is the primary reaction to an anticipated constraint in water supply. Water productivity (value of production divided by the volume of irrigation water delivered; WP) in the district was moderate and highly variable (around 2€ m⁻³) and did not increase with time. Irrigation water productivity (increase in production value due to irrigation divided by irrigation water delivered) was much lower (0.65€ m⁻³) and also, it did not increase with time. The lack of improvement in WP, the low irrigation water usage, and the changes in cropping patterns over the first 15 years of operation indicate that performance trends in irrigated agriculture are determined by a complex mix of technical, economic, and socio-cultural factors, as those that characterized the behaviour of the Genil-Cabra irrigation scheme.     

基础设施投资促进国有农场产业结构升级机制及实证研究

产业结构升级是经济高质量发展的必经之路，产业结构升级离不开作为经济高质量发展必要前提的基础设施先行资本投资的支持。基础设施投资与国有农场产业结构升级之间存在相互作用与循环发展机制。探讨基础设施投资促进国有农场产业结构升级的关系与机制有助于为国有农场摆脱发展困境提供理论启示。运用VAR模型和脉冲响应函数等计量方法，以农垦系统国有农场为研究对象，利用2004—2017年《中国农垦统计年鉴》数据探讨了农垦系统国有农场基础设施投资与产业结构升级之间的关系，发现基础设施投资对产业结构升级存在长期拉动效应，依据该长期效应提出了建立专门基金、明确基础设施投资年限、坚持持续投入资金等政策建议      

Evaluating drip irrigation in commercial tea production in Tanzania

This paper evaluates the performance of the first drip irrigation scheme in commercial tea production in Tanzania with a view to making recommendations for improved management and providing data for investment decisions. Uniformity, efficiency and adequacy of irrigation were calculated and the scheduling of irrigation water was reviewed. Operators were interviewed to highlight the main benefits and problems of the system. Investment and recurrent costs of drip and overhead sprinkler systems were quantified and compared. Root development was assessed qualitatively using excavation pits. Irrigation uniformity DU and efficiency ranged between 88 and 95% in the 10 out of 14 irrigation blocks where endline pressures were at least 0.5 bars, and between 77 and 89% in the four blocks were endline pressure was less than 0.5 bars. Scheduling drip irrigation using tensiometers offered potential water savings of 26% in comparison to a water balance schedule, but these are not currently realised. Gross marginal income was very sensitive to tea price and yield. Economically optimal fertilizer rates vary in dependence of tea price and yield and appear to be lower than the current level of 300 kg N ha⁻¹. The higher costs under drip, compared to overhead sprinklers, were mainly for purchase and installation and fertilizer. The costs of labour for applying water and fertilizer were reduced by nearly 50%. At average 2002 tea prices of 1.31 US$ kg⁻¹, drip irrigation would improve the grower’s gross margin if an additional yield of at least 411 kg ha⁻¹ was achieved. The main threats to drip system performance are discussed. Future research efforts should aim at establishing the yield response of tea to water and fertilizer under drip irrigation.     

I. A decision support system to improve planning and management in large irrigation schemes

This paper describes a decision support system (DSS) that was developed to improve planning and management for the large irrigation schemes in the Alentejo region of Portugal. The system was designed to help in the analysis and evaluation of the crops and crop systems that can potentially be cultivated, together with identification of limitations affecting crop selection and crop yields. It integrates socio-economic and biophysical data at the field level to analyse the performance of an irrigation scheme in terms of the adoption of irrigation by farmers and farmers’ incomes. The final output is given in the form of specific actions and policies for the irrigated areas. The DSS was designed initially to be used in the Alqueva project, a large irrigation scheme that is under construction in Alentejo. Nevertheless, the final framework is generic in nature, being suitable for planning and policy evaluation in other large irrigation schemes.     

Application of the Analytic Hierarchy Process to irrigation project improvement: Part II. How professionals evaluate an irrigation project for its improvement

Planning improvement of an irrigation project often depends on irrigation professionals who conduct the initial survey of the irrigation project. Accordingly, activities for improvement will be different depending on who evaluates the status quo of the irrigation project, because of the diversity of expertise and experience of professionals. A questionnaire survey was conducted to examine how irrigation professionals evaluate an irrigation project, that is, on what evaluation factors (EFs) they place the importance. In the questionnaire, professionals ranked the relative importance of EFs derived from internal process indicators of the Rapid Appraisal Process (RAP). Answers to the questionnaire were processed by the Analytic Hierarchy Process (AHP, Part I), and then local weights of EFs were obtained as a measure of relative importance of EFs. Those local weights were statistically analyzed by the Anderson-Darling normality test, the F-test and the t-test. Then, they were modeled by probability density functions. The results implied (a) that irrigation professionals give the first priority to water delivery services project-wide and (b) that they consider that irrigation infrastructure (hardware) of primary canals is more important than that of secondary canals. These findings infer that irrigation professionals first consider how well water is controlled and distributed project-wide and second how appropriately primary canals are designed and maintained. Also, their views are divided into two regarding importance of hardware and management, namely some insist that hardware is more important than management and the others insist that management is more important than hardware.     

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

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