共查询到20条相似文献，搜索用时 15 毫秒
1.
Peter Smith 《Irrigation and Drainage Systems》1987,1(3):277-286
The constraints on the effectiveness of twenty one deep tubewell schemes in Tangail, Mymensingh and Jamalpur Districts were studied. Major problems were the difficulty of constructing small earthworks (aqueducts), inconsistencies in credit provision, and the non-availability of HYV rice varieties with appropriate characteristics to exploit the irrigation. Research on farmer's cropping choice is reported, and conclusions aer drawn on issues of equity and project identification.Abbreviations DTW
deep tubewell
- BADC
Bangladesh Agricultural Development Corporation
- IRDP
Integrated Rural Development Project
- XEN
Executive Engineer 相似文献
2.
3.
The non-uniformity of soils, weather, fields, cropping pattern and canal systems in most surface irrigation schemes makes irrigation water management complex, but optimum performance is important particularly in irrigation schemes with limited water supply. This paper focuses on the performance of irrigation water management during the area and water allocation with a case study of an irrigation scheme in the semi-arid region of India. Often the irrigation managers or authorities of these heterogeneous irrigation schemes also need to deal with different allocation rules. The allocation plans and the corresponding water delivery schedules during the allocation process were estimated with the help of a simulation–optimisation model for different allocation rules based on cropping distributions (free and fixed), water distributions (free and fixed-area proportionate), irrigation depth (full, fixed depth and variable depth irrigation) and irrigation interval (from 14 to 35 days). The performance measures of productivity (in terms of net benefits and area irrigated), equity (in water distribution), adequacy and excess were assessed for these different allocation plans and schedules. These were further compared with the performance measures of the existing rule (fixed depth irrigation at a fixed interval). The analysis revealed that these performance measures are in some cases complimentary and in other cases conflicting with each other. Therefore, it would be appropriate for the irrigation managers to understand fully the nature of the variation in performance measures for different allocation rules prior to deciding the allocation plans for the irrigation scheme. 相似文献
4.
Performance assessment of irrigation water management of heterogeneous irrigation schemes: 1. A framework for evaluation 总被引：1，自引：0，他引：1
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. 相似文献
5.
Mandivamba Rukuni 《Irrigation and Drainage Systems》1988,2(2):199-210
Voluntary smallholder irrigation schemes in Zimbabwe were launched in 1913 as a means of famine relief and subsequently to settle black farmers displaced from designated areas for white commercial farmers. In 1928 the colonial government inaugurated a programme to provide services to existing smallholder schemes and to assist in developing new schemes. This process eventually led to the erosion of farmer participation in planning, development and financing of smallholder schemes. Since 1928 the smallholder schemes have been heavily subsidised, a pattern that continues today. Currently about 3.4% of the land under irrigation is farmed by small holders who pay about 11% of the costs of irrigation operation and maintenance; the remaining 89% is subsidised by the government. More smallholder irrigation development is currently being planned. The government has made loan funds available to groups on the basis of financial viability, but to date this fund has not been significantly utilized by smallholders. In essence, smallholder irrigation development is being constrained by problems that have plagued smallholder schemes since 1928.Abbreviations AGRITEX
Agricultural Technical and Extension Services
- ARDA
Agricultural and Rural Development Authority
- DERUDE
Department of Rural Development
- NFIF
National Farm Irrigation Fund
- Z$
Zimbabwe Dollar 相似文献
6.
7.
This paper focuses on irrigation schemes under rotational water supply in arid and semiarid regions. It presents a methodology
for developing plans for optimum allocation of land area and water, considering performance measures such as productivity,
equity and adequacy. These irrigation schemes are characterized by limited water supply and heterogeneity in soils, crops,
climate and water distribution network, etc. The methodology proposed in this paper, therefore, uses a previously developed
simulation–optimization model (Area and Water Allocation Model, AWAM) that considers the heterogeneity of the irrigation scheme
in the allocation process, and modifies this to take account of equity and adequacy of supply to irrigated areas. The AWAM
model has four phases to be executed separately for each set of irrigation interval over the irrigation season: 1. generation
of irrigation strategies for each crop–soil–region combination (CSR unit), 2. preparation of irrigation programmes for each
irrigation strategy, 3. selection of specified number of irrigation programmes for each CSR unit and 4. optimum allocation
of land area and water to different parts of the irrigation scheme (allocation units) for maximizing productivity. In the
modified AWAM model, the adequacy is included at Phase-2 (by including only the irrigation programmes for full irrigation
of each CSR unit) and equity is included at Phase-4 (by including the constraints for equity). The paper briefly discusses
the applicability of the modified AWAM model for a case study of Nazare medium irrigation scheme in Southern India. The results
of the case study indicated that the performance measures of productivity, equity and adequacy conflict with each other. 相似文献
8.
Herve L. Plusquellec Kathryn McPhail Christian Polti 《Irrigation and Drainage Systems》1990,4(4):313-327
This paper presents the results of assessment studies of the performance of gravity irrigation projects, in six countries in different climate and social environments, with respect to their original objectives in terms of water availability, water use efficiencies, equity of water distribution, cropping intensity and crop yields, and project economic rates of return.An important lesson is the need for more realistic assumptions in the adoption of design standards, especially irrigation efficiency which affect the cropping intensity, the overall productivity of the project and its economic viability. This comparative method of performance assessment applied to a variety of projects has also provided some useful insights into the relative value of the different approaches to design of gravity irrigation systems.The views expressed in this paper are those of the author and are not presented as official views of the World Bank. 相似文献
9.
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. 相似文献
10.
Irrigation policy makers and managers need information on the irrigation performance and productivity of water at various scales to devise appropriate water management strategies, in particular considering dwindling water availability, further threats from climate change, and continually rising population and food demand. In practice it is often difficult to access sufficient water supply and use data to determine crop water consumption and irrigation performance. Energy balance techniques using remote sensing data have been developed by various researchers over the last 20 years, and can be used as a tool to directly estimate actual evapotranspiration, i.e., water consumption. This study demonstrates how remote sensing-based estimates of water consumption and water stress combined with secondary agricultural production data can provide better estimates of irrigation performance, including water productivity, at a variety of scales than alternative options. A principle benefit of the described approach is that it allows identification of areas where agricultural performance is less than potential, thereby providing insights into where and how irrigation systems can be managed to improve overall performance and increase water productivity in a sustainable manner. To demonstrate the advantages, the approach was applied in Rechna Doab irrigation system of Pakistan’s Punjab Province. Remote sensing-based indicators reflecting equity, adequacy, reliability and water productivity were estimated. Inter- and intra-irrigation subdivision level variability in irrigation performance, associated factors and improvement possibilities are discussed. 相似文献
11.
Management trends and responses to water scarcity in an irrigation scheme of Southern Spain 总被引：1，自引：0，他引：1
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. 相似文献
12.
Jahirul Islam Lukmanur Rahman Bhuiyan Abdul Ghani 《Irrigation and Drainage Systems》1991,5(4):351-362
The study was conducted in Monsoon (Transplanted Aman) at BRRI farm, Joydebpur, from 1978–1987, to determine the impact and viability of supplemental irrigation. The results of 8 years of experimentation indicate that the impact of supplemental irrigation mainly depends on rainfall distribution patterns and the last precipitation of the season. Generally, the late transplanted crops suffer from moisture stress when the last rainfall ceases by the first week of October. Under this situation, one timely supplemental irrigation of 60 mm could produce about 58% more yield, and the consequent benefit cost ratio of supplemental irrigation would be 5.3 to 14.5, which is highly profitable. The study reveals that if the last rainfall continues up to the third week of October, the supplemental irrigation is still profitable. When sufficient rainfall occurs in November, there is no need for supplemental irrigation, even in late transplanting, and continuous standing water is not required for rice cultivation provided the rain water can be managed properly.Abbreviations BADC
Bangladesh Agriculture Development Corporation
- B/C Ratio
Benefit Cost Ratio
- BRRI
Bangladesh Rice Research Institute
- HYV
High Yielding Variety 相似文献
13.
新疆石河子农七师某团一连队地处库尔班通古特沙漠西南端，周围有大面积的沙漠和戈壁滩，水资源匮乏，为科学有效地利用有限水资源，系统上位机通过Internet、GPRS网络和现场泵房PLC进行通讯，实现整个连队所有灌区的节水灌溉自动控制集中管理。该系统结构简单，性能稳定，响应时间短，数据实时性好，节水效果显著，得到用户的一致好评。 相似文献
14.
Shahbaz Khan Tariq Rana Munir A. Hanjra John Zirilli 《Agricultural Water Management》2009,96(3):493-503
Agricultural water markets can facilitate adjustments to water scarcity and competition and enhance economic efficiency, but markets cannot automatically balance efficiency, equity and environmental sustainability goals. The consequences of water trading on soil salinity in irrigation areas are not yet fully understood, but recognized as an issue that needs to be analysed. This paper explores the nexus between water trading and groundwater-induced soil salinity in a selected irrigated area in the Murray-Darling Basin. Results show that minimum irrigation intensities must be met to flush salts out of the root zone especially in shallow water table/high salinity impact areas. Such minimum irrigation intensities are helpful but not necessarily in deep water table/low salinity impact areas. Should water markets lead to permanent water transfers out of mature irrigation areas, minimum irrigation intensity needs might not be met in high salinity impact areas, causing substantial negative impacts on resource quality and agricultural productivity. Water trading that adds to salinity cannot be economically viable in the long run. The tradeoffs between water trading and environmental and equity goals need to be determined. This work contributes to the wider debate on Australian water policy aimed at achieving water security through water trading in the Murray-Darling Basin. 相似文献
15.
Beyond irrigation efficiency 总被引：3，自引：2，他引：3
Marvin E. Jensen 《Irrigation Science》2007,25(3):233-245
Parameters for accounting for water balance on irrigation projects have evolved over the past century. Development of the
classic term irrigation efficiency is summarized along with recent modifications such as effective irrigation efficiency. The need for terms that describe measurable water balance components of irrigated agriculture is very important, as demands
and competition for available renewable water supplies continue to increase with increasing populations. Examples of irrigation
efficiency studies conducted during the past few decades are summarized along with related irrigation terminology. Traditional
irrigation efficiency terminology has served a valid purpose for nearly a century in assisting engineers to design better
irrigation systems and assisting specialists to develop improved irrigation management practices. It still has utility for
engineers designing components of irrigation systems. However, newer irrigation-related terminology better describes the performance
and productivity of irrigated agriculture. On a river-basin level, improved terminology is needed to adequately describe how
well water resources are used within the basin. Brief suggestions for improving irrigation water management are presented. 相似文献
16.
李太山 《农业机械化与电气化》2014,(6):85-86
针对目前多数灌区供水体制管理中存在的问题,围绕水权探讨改革措施。指出模糊水权是灌区用水的制约因素,概述灌区水权改革历程,分析水管理部门、灌区管理机构和用水户的关系,提出应保障灌区用水转让权、明晰水权与灌区资产权利关系,为灌区供水体制管理改革提供参考。 相似文献
17.
紫花苜蓿每年刈割多次,其不同茬次间的耗水规律与灌溉制度存在较大差异.在鄂尔多斯市鄂托克前旗牧区节水灌溉示范区进行紫花苜蓿中心支轴式喷灌灌溉试验,利用水量平衡原理计算得出喷灌条件下不同茬次紫花苜蓿耗水量,研究分析不同茬次紫花苜蓿耗水规律、产量、水分生产率和灌溉制度.结果表明:研究区第一、二和三茬紫花苜蓿耗水量总体呈现递增趋势,而不同茬次紫花苜蓿耗水强度呈现低-高-低变化规律;不同茬次紫花苜蓿产量差异明显,其中第二茬紫花苜蓿产量最高,第一茬产量次之,第三茬产量最低,对应不同茬次紫花苜蓿水分生产率也呈现相同的变化规律;一般年份紫花苜蓿喷灌条件下推荐灌溉制度为全生育期灌水7次,灌溉定额270~315 mm,其中第一茬灌水3次,灌溉定额120~135 mm,第二茬灌水2次,灌溉定额75~90 mm,第三茬灌水2次,灌溉定额75~90 mm.该研究成果对于多茬牧草灌溉决策和牧区节水灌溉工程设计具有一定意义. 相似文献
18.
19.
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. 相似文献
20.
Irrigation reliability and the productivity of water: A proposed methodology using evapotranspiration mapping 总被引：1，自引：0，他引：1
Chris Perry 《Irrigation and Drainage Systems》2005,19(3-4):211-221
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. 相似文献