Assessing the groundwater dynamics and impacts of water saving in the Hetao Irrigation District, Yellow River basin

Water resources allocated to the agricultural sector in the Yellow River basin are being reduced due to severe water scarcity and increased demand by the non-agricultural sectors. In large-scale irrigation districts, the application of water-saving practices, e.g., improving the canal system, using water-saving irrigation technology and adjusting cropping patterns, is required for the sustainable agricultural development and the river basin environmental equilibrium. Adopting water-saving practices leads to lowering the groundwater table and to controlling salinity impacts related to excessive irrigation. However, assessing the effects of water-saving practices on the groundwater system requires further investigation. The Jiefangzha Irrigation Scheme of the Hetao Irrigation District is used as a case study for analyzing the temporal and spatial dynamics of the groundwater table. A lumped parameter groundwater balance model has been developed with this purpose and to assess impacts of various water-saving practices. The model was calibrated with monthly datasets relative to the non-frozen periods of 1997-1999 and validated with datasets from 2000 to 2002. Results indicate that canal seepage and deep percolation account for respectively 48% and 44% of the annual groundwater recharge. Groundwater discharge by direct evaporation and plant roots uptake represents 82% of the total annual groundwater discharge. After validation, the model was applied to assess the impacts of various canal and farm irrigation water-saving practices. It was observed that improvements in the canal system (e.g., canal lining, upgrading the hydraulic regulation and control structures, improving delivery schedules) might lower the groundwater table by 0.28-0.48 m, depending upon the level of implementation of these measures. Higher declines of the groundwater table are predicted when water-saving technologies are applied at both the canal and the farm systems. That decline of the water table favours salinity control and reduces capillary rise, thus reducing the groundwater evaporation and uptake by plant roots; that reduction may attain 128 mm. However, predictions may change depending on the way how water-saving measures are applied, which may be different of assumptions made; therefore, there is the need to perform a follow-up of the interventions in order to update predictions. Results indicate the need for appropriate research leading to improved irrigation management when the decline of the groundwater level will reduce groundwater contribution to vegetation growth.     

Long-term water balances in La Violada Irrigation District (Spain): II. Analysis of irrigation performance

The analysis of long-term irrigation performance series is a valuable tool to improve irrigation management and efficiency. This work focuses in the assessment of irrigation performance indices along years 1995-2008, and the cause-effect relationships with irrigation modernization works taking place in the 4000 ha surface-irrigated La Violada Irrigation District (VID). Irrigation management was poor, as shown by the low mean seasonal irrigation consumptive use coefficient (ICUC = 51%) and the high relative water deficit (RWD = 20%) and drainage fraction (DRF = 54%). April had the poorest irrigation performance because corn (with low water demand in this month) was irrigated to promote its emergence, whereas winter grains (with high water demands in this month) were not fully irrigated in water-scarce years. Corn, highly sensitive to water stress, was the crop with best irrigation performance because it was preferentially irrigated to minimize yield losses. The construction of a new elevated canal that decreased seepage and drainage fractions, the entrance in operation of six internal reservoirs that would increase irrigation scheduling flexibility, and the on-going transformation from surface to sprinkler irrigation systems are critical changes in VID that should lead to improved ICUC, lower RWD and lower DRF. The implications of these modernization works on the conservation of water quantity and quality within and outside VID is further discussed.     

Greenhouse gas implications of water reuse in the Upper Pumpanga River Integrated Irrigation System, Philippines

Enhancing water productivity is often recommended as a “soft option” in addressing the problem of increasing water scarcity. However, improving water productivity, particularly through water reuse, incurs additional investment and may result in increased greenhouse gas (GHG) emissions. In this study, we analysed the water productivity and GHG implications of water reuse through pumping groundwater and creek water, and compare this with gravity-fed canal irrigation in the Upper Pampanga River Integrated Irrigation System (UPRIIS) in the Philippines.Water productivity indicators show that water reuse contributes significantly to water productivity. For example, water productivity with respect to gross inflow (WP_gross) with water reuse (0.19 kg grain/m³) is 21% higher than without water reuse (0.15 kg grain/m³). However, there is a tradeoff between increasing water productivity and water reuse as water reuse increases GHG emissions. The estimated GHG emission from water reuse (pumping irrigation) is 1.47 times higher than without water reuse (gravity-fed canal irrigation). Given increasing concerns about climate change and the need to reduce carbon emissions, we recommend that a higher priority be given to water reuse only in areas where water scarcity is a serious issue.     

典型小型灌区渠系老化对农田灌溉的影响-以贵州省乌中灌区为例

乌中灌区是贵州省的大型灌区之一,灌区工程多修建于上世纪50至70年代。至今,大多渠道老化难以正常工作,渠系老化率平均达0.55;灌区有效灌溉面积锐减,现状有效灌溉面积为设计灌溉面积的37%-54%,其中改种占相当比例;灌溉水利用系数较低,在0.39—0.42之间。本文以5个典型样点灌区为例,分析渠系老化对农田灌溉的影响。     

自适应指数平滑预报模型在灌区需水量预报中的应用

本文详述了指数平滑预报模型建模原理，并根据灌区需水量预报的具体特点，着重探讨了模型的自适应控制及模型参数的选取和初值的确定方法。实例预报结果表明，把自适应指数平滑预报模型应用于灌区需水量预报中是可行的。     

Modelling seawater intrusion in the Burdekin Delta Irrigation Area,North Queensland,Australia

The Burdekin Delta is a major irrigation area situated in the dry tropics of North Queensland. It is unique in that (i) it overlies shallow groundwater systems that serve as a major water supply for the irrigation of sugarcane, and (ii) it is adjacent to the world heritage listed Great Barrier Reef. Water management practices include large recharge pits and surface spreading of water to assist with replenishment of the groundwater. This has been useful in maintaining groundwater levels to help control seawater intrusion. This technique, however, can be costly and ineffective in unconfined aquifer systems, which are subjected to large amounts of groundwater pumping for irrigation. There are more than 1800 production bores currently used for irrigation in the Burdekin Delta and the large volumes of water extracted have at times lowered the regional water tables and made it difficult to control seawater intrusion.     

Irrigation scheduling strategies for cotton to cope with water scarcity in the Fergana Valley, Central Asia

The Central Asian countries face high water scarcity due to aridity and desertification but excess water is often applied to the main irrigated crops. This over-irrigation contributes to aggravate water scarcity problems. Improved water saving irrigation is therefore required, mainly through appropriate irrigation scheduling. To provide for it, after being previously calibrated and validated for cotton in the Fergana region, the irrigation scheduling simulation model ISAREG was explored to simulate improved irrigation scheduling alternatives. Results show that using the present irrigation scheduling a large part of the applied water, averaging 20%, percolates out of the root zone. Several irrigation strategies were analyzed, including full irrigation and various levels of deficit irrigation. The analysis focused a three-year period when experiments for calibration and validation of the model were carried out, and a longer period of 33 years that provided for an analysis considering the probabilities of the demand for irrigation water. The first concerned a wet period while the second includes a variety of climatic demand conditions that provided for analyzing alternative schedules for average, high and very high climatic demand. Results have shown the importance of the groundwater contribution, mainly when deficit irrigation is applied. Analyzing several deficit irrigation strategies through the respective potential water saving, relative yield losses, water productivity and economic water productivity, it could be concluded that relative mild deficits may be adopted. Contrarily, the adoption of high water deficit that produce high water savings would lead to yield losses that may be economically not acceptable.     

柳州市郊县灌溉水养分元素含量

本文研究了柳州市郊柳江、柳城和来宾三县的灌溉水养分元素含量和pH值。含氮0.52～0.87mg/L,磷0.003～0.024mg/L,钾0.81～1.19mg/L,钠0.99～1.52mg/L,钙29.44～73.28mg/L,镁5.14～17.20mg/L,硫1.02～1.60mg/L,氯2.68～7.40mg/L和氟0.15～0.24mg/L。pH8.33～8.44。在9种元素中,硫随季节变化比较明显。钾、钠、镁和硫、氯随流程增长含量增加。     

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.     

Farmer participation in irrigation management: The case of Doroodzan Dam Irrigation Network, Iran

The importance of farmer participation in system design and management has been emphasized in previous studies. The purpose of this study was to identify the factors affecting farmer participation in irrigation management using survey research. The study was conducted in Doroodzan Dam Irrigation Network in Fars province, Iran. Multistage stratified random sampling was used to collect data from 270 farmers as the research sample. Results reveal that farmers’ attitudes toward participation in irrigation management, attitudes toward personnel of the State Water Authority and the Agricultural Extension Service Centers (AESCs), family size, the problem perception, dependence on the dam for water, and educational background have influenced their participation in irrigation management. By contrast, contact with information sources, animal units, sociability, age and agricultural experience did not affect farmers’ participation. Moreover, based on farmers’ perspectives, unequal water distribution among farms, dissatisfaction with Water Authority operators and high water fees and charges were the main problems and obstacles toward farmer participation in irrigation management.     

漳河灌区节水灌溉影响分析

为了解决越来越严重的水资源危机，发展节水灌溉已经成为灌区越来越重要的任务。自改革开放以来，漳河灌区灌溉用水量有了大幅度下降，而农业生产总产量却有所上升。灌区通过节水灌溉，使得灌溉水分生产率不断提高，在保证农业生产总产量稳步提高的前提下节约灌溉用水。与此同时，将所节约的农业灌溉用水转移到如发电、城镇供水、工业用水等非农业用水部门，从而大大提高了单方水利用效益。这是我国开展节水灌溉较为成功的典范。通过研究漳河灌区节水灌溉的影响，寻求大型灌区真实节水的途径，使得有限的水资源得到更加充分、合理的利用。     

提高藏东地区节水灌溉水平的几点思考

灌区渠道渗漏、坍塌现象突出,致使过水能力、灌溉水利用系数低的问题在藏东地区十分严重,,主要原因既有地质条件等客观因素,也有规划建设和营运管理相对落后等主观原因。要解决这一问题,除了采用管理和技术手段维护好现有的灌溉工程外,更重要的是还要在解决农牧区新灌区规划设计及灌溉节水的工作思路上有所突破。     

Irrigation with saline water: benefits and environmental impact

The shortage of water resources of good quality is becoming an important issue in the arid and semi-arid zones. For this reason the availability of water resources of marginal quality such as drainage water, saline groundwater and treated wastewater has become an important consideration. Nevertheless, the use of these waters in irrigated lands requires the control of soil salinity by means of leaching and drainage of excess water and salt. However, the leaching of salts, soil microelements and agro-chemicals can lower the quality of the drainage water in the irrigation scheme. The irrigation return flows with water or poor quality are a source of pollution of the surface water bodies situated downstream of the drainage outlet. Deep percolation could also contaminate the groundwater. Therefore, irrigation with saline water requires a comprehensive analysis even beyond the area where water is applied. The problem should be treated beyond the scope of the irrigation scheme, taking into consideration the groundwater and downstream surface water resources of the river basin. Consequently, the sustainable use of saline water in irrigated agriculture requires the control of soil salinity at the field level, a decrease in the amount of drainage water, and the disposal of the irrigation return flows in such a way that minimizes the side effects on the quality of downstream water resources. This paper describes the guidelines for a preliminary evaluation of the suitability of water for irrigation and the key factors for salinity control in lands irrigated with saline water. Options to improve the quality of the drainage water, strategies for the reuse of this water and alternatives for disposal of the outflow are also analysed. The final goal is to obtain sustainable agriculture and maintain the quality of the water resources in the river basin.     

内蒙古河套灌区秋浇对区域尺度地下水水化学影响分析——以义长灌域为例

【目的】了解灌区秋浇对区域地下水水化学过程的影响。【方法】在测试八大离子(Na+、K+、Ca2+、Mg2+、SO42-、Cl-、HCO3-、CO32-)的基础上,综合运用数理统计和水文地球化学分析方法,分析灌区地下水水化学特征。【结果】灌溉后,该灌域整体上Cl-、SO42-、K++Na+、Mg2+、HCO3-的质量浓度增大,而Ca2+质量浓度略有减小,TDS呈现南高北低的分布状态;根据Piper 三线图分析,灌溉前后该区域地下水类型均以Cl-Na型为主,占比分别为75%和61%,相比灌溉前,灌溉后出现Mg-SO4-Cl 型,占比约为16.7%;由Gibbs 模式和离子比例系数图得出,该区域地下水主要受蒸发浓缩以及硅铝酸盐和蒸发岩风化溶滤作用的控制,大气降水对其影响不大。【结论】秋浇之后地下水TDS平均增加约32.9%,说明秋浇对土壤盐分的淋滤作用明显,加强秋浇之后地下水排水力度,对于提高灌区排水排盐效果具有十分重要的作用。     

双牌灌区灌溉用水有效利用系数计算分析

本文分析了测算双牌灌区灌溉用水有效利用系数的意义,系统阐述了灌溉用水有效利用系数的测算方法,探讨了影响灌溉用水有效利用系数的具体因素.研究成果可为灌区灌溉用水有效利用系数的测算和灌区的水管理提供理论依据.     

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).     

河套灌区永济灌域地下水数值模拟

以内蒙古河套灌区永济灌域为研究对象,采用Visual Modflow软件建立了地下水三维非稳定流模型,运用手动调参和Pest模块调参相结合进行参数率定,选取的14口观测井的观测值和模拟值趋于一致,表明本文率定的参数合理,具有较高的精度。利用该模型模拟了不同开采方案下的地下水埋深变化,同一开采条件下,灌区南部地下水位埋深下降相对北部和中部较小,可适当加大南部的地下水开采量来减少引黄灌溉,该模拟结果存在一定的实用价值。     

河套灌区小麦套种玉米灌溉制度研究

为研究河套灌区小麦套种玉米高产、节水的灌溉制度,在田间试验的基础上分析了小麦套种玉米模式下的耗水规律,运用Jensen模型建立水分生产函数并对灌溉制度进行了优化。结果表明:小麦拔节、抽穗、灌浆及玉米抽雄、灌浆期是作物生长的关键期,适宜的水分条件是促进产量形成的重要因素;通过多元线性回归方法求解得出敏感性指数分别为小麦分蘖-拔节期(0.305 0)、小麦拔节-抽穗期(0.335 6)、小麦抽穗-灌浆期(0.143 2)、玉米拔节-抽雄期(0.320 7)、玉米抽雄-灌浆期(0.310 2);以产量最大为目标函数得出小麦套种玉米最优灌溉制度为:小麦分蘖-拔节期95mm,拔节-抽穗期105~110mm,抽穗-灌浆期65~70mm,玉米拔节-抽雄期95~105mm,抽雄-灌浆期100~105mm,全生育期以460~485mm的灌溉供水量为宜。     

河套灌区节水灌溉对土壤盐分累积规律的模拟研究

在内蒙古河套实施农业节水对引黄灌区水资源可持续利用具有非常重要的意义。通过河套灌区土壤水盐动态的原位监测,并应用水盐运移和作物耦合模型HYDRUS-EPIC对不同灌溉条件下葵花土壤盐分累积规律进行分析。研究结果表明:现状滴灌条件下葵花生育期土壤表层(0~10cm)盐分呈累积趋势,全盐含量分别比传统地面灌溉和等量地面灌高115%和37%;葵花生育期0~100cm增加的全盐量(ΔC)滴灌比传统地面灌溉高305%,比等量地面灌溉低23%,淋洗是灌区滴灌不可或缺的抑盐措施;滴灌条件下葵花的产量比传统地面灌小6.5%;滴灌产量比等量地面灌高11.7%,增产效果明显。