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1.
Monterrey metropolitan area’s growth has resulted in water transfers from the Río San Juan basin with significant impacts for downstream water users, especially farmers in the Bajo Río San Juan (BRSJ) irrigation district. El Cuchillo dam is the centerpiece of the basin’s water management infrastructure and has become the flashpoint of a multi-faceted water dispute between the states of Nuevo León and Tamaulipas as well as between urban and agricultural water interests in the basin. Subsequent to El Cuchillo’s implementation in 1994, the BRSJ irrigation district has been modifying its irrigation operations to adjust to the new water availability scenario. Compensation arrangements for farmers have been established, including crop loss payments on the order of US$ 100 per hectare un-irrigable due to the diversion of water to Monterrey plus 60% of the water diverted to be returned to farmers as treated effluent via the Ayancual Creek and Pesquería River, a process with its own water competition and environmental implications. The Mexican irrigation sector will continue to face intense competition for water given: (a) low water productivity in agriculture leading decision-makers to allocate water to higher productivity uses particularly in cities, (b) priority accorded to the domestic use component of municipal water supply, and in the BRSJ case, (c) Mexico’s national interests in meeting its water sharing obligations with the United States.  相似文献   

2.
The Lower Rio Grande Valley is a sub-tropical area with a productive irrigated agriculture, but with an over-committed single water resource. It is experiencing a rapidly growing population that is placing increasing pressure on the water resource. This, combined with expanding urban areas and land moving out of agriculture, has resulted in a vigorous water market, with transfers from agriculture to municipal uses. For the US portion of the valley, transfers from agriculture to municipalities are either short-term (usually 1 year) or permanent. Prices vary depending upon the location and timing, and result from negotiations between the parties. Over time, and not without difficulty, the water market has been facilitated by appropriate enabling legislation, water rights that have been validated judicially, and an efficient transfer mechanism that has a minimum of transaction cost. Government involvement is primarily for protection of the public, and to facilitate the transfer process.
G. LevineEmail:
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3.
Two type of water transfer have occurred in Taiwan, namely, regular and emergency transfers. According to the prevailing Water Law, water is permitted to transfer among water rights holders whenever they need and agree upon relevant compensation. As for the emergency transfer, in the event of extensive drought, every water user sector will suffer serious water shortages resulting in unavoidable economic losses. The Government should step in to perform emergency water transfer by suspending agricultural water rights a course of action considered to cause smaller losses even when an entire rice crop is abandoned, to minimize overall losses to the national macro economy. This study has examined two typical water transfer cases that were implemented in Taiwan. The first one involved the regular transfer of agricultural water from the Changhwa and Yunlin Irrigation Associations (IAs) to the industrial user Formosa Petrochemical Corporation (FPC). The second one involved the transfer of agricultural water from the Taoyuan, Shimen and Shinchu IAs to domestic and industrial uses during the period from 2002 to 2006 as an emergency transfer. From the perspective of water transfer options, Taiwanese case studies have demonstrated that an officially recognized marketing oriented water transfer mechanism has yet to be established. However, water transfer is still undertaken whenever necessary. In this respect, regardless of the type of water transfer undertaken, water rights can only be suspended but not terminated. In spite of the types of water transfer, it is inevitable to affect the ecological and environmental functions. Therefore, further investigations with related topics should be broadly taken into account. Ecosystem services of paddy fields have attracted increasing recognition in the monsoon Asian countries. Currently, there is a research program collaborating with the International Water Management Institute (IWMI) on the impact and influence induced by water transfer with a major concern on the ecosystem services of paddy fields in Taiwan.  相似文献   

4.
The Zhanghe irrigation system (ZIS) is located in the Yangtze River Basin approximately 200 km west of Wuhan in Hubei Province. The reservoir was designed for multiple uses—irrigation, flood control, domestic water supply, industrial use, aquaculture, and hydropower. Over a period of more than 30 years a steadily increasing amount of water has been transferred from irrigation to other uses. Activities on the part of government, irrigation system managers, and farmers made this transfer possible with only modest decline in rice production. Most important factor was the steady increase in rice yields. The water pricing system provided an incentive for ZIS to reduce irrigation releases. With the steady decline in releases, farmers were forced to find ways to save water. Farmers improved existing ponds and built new ones to store water (improved infrastructure). Access to pond water on demand facilitated the adoption of alternate wetting and drying (technology) particularly in dry years. The establishment of volumetric pricing (price policy) and water user associations (institutions) may also have provided incentives for adoption of AWD, but more research is needed to establish their impact. These activities taken together can be seen as potentially complementary measures. Farmers received no direct compensation for the transfer of water, but recently farm taxes have been reduced or altogether abolished. Further reduction in water releases from the ZIS reservoir could adversely affect rice production in normal or dry years.  相似文献   

5.
《Plant Production Science》2013,16(5):592-600
Abstract

This research was conducted to determine the yield and water-use efficiency of maize under fixed and variable alternate furrow irrigation (fixed AFI, variable AFI) and every furrow irrigation (EFI) at different irrigation intervals in areas with shallow and deep groundwater. In variable AFI, water was applied to the furrow, which was dry in the previous irrigation cycle. The results indicated that even at 4-day irrigation intervals the water needs of maize on a fine textured soil in both areas (with deep and shallow water table) are not met by AFI. The decrease in grain yield due to water stress was mainly due to the decrease in the number of grains per cob and to a lesser extent to the decrease in 1000-grain weight. At the Kooshkak site with shallow groundwater (between 1.31 and 1.67 m), grain yields in AFI at 4- and 7-day intervals were comparable to those obtained in EFI at 7- and 10-day intervals, respectively. This might be due to the contribution of groundwater to the water use of the plant (about 5-10%). In the Badjgah area, with deep water depth, grain yield in AFI at 7-day intervals was statistically lower than that obtained in EFI at 10-day interval. In AFI, a shorter irrigation interval (4-day) may alleviate the water stress and result in no yield reduction compared with that in EFI at 7-day intervals even though water application was reduced. Furthermore, in the area with a shallow water table, AFI at 7-day intervals may be superior to EFI at 10-day irrigation intervals. When seasonal irrigation water is less than 700 mm, it may be preferable to use AFI at 10-day intervals to increase water-use efficiency, especially in areas with shallow groundwater. In general, when water was insufficient for full irrigation, the relative grain yield (yield per unit water applied) of maize under AFI was higher than those under EFI.  相似文献   

6.
The association of specific target traits for drought resistance (early flowering, high accumulation of stem water soluble carbohydrate (WSC) reserves, presence of awns and high green flag-leaf area persistence) with yield performance under late-season drought was analyzed utilizing two doubled-haploid (DH) populations derived from crosses between Beaver × Soissons and Rialto × Spark in two seasons 2000/2001 and 2001/2002. The aim was to quantify associations between target traits and yield responses to drought, and to prioritize traits for drought resistance. Flowering time variation had a neutral effect on the absolute yield loss under drought, suggesting there may be a trade-off between water-saving behaviour in the shorter pre-flowering period with early flowering and a reduced capacity to access water associated with a smaller rooting system. The presence of awns also had a neutral effect on yield loss under drought amongst lines of the Beaver × Soissons population. The potential advantages of awns for increasing water-use efficiency and sensible heat transfer responsible for a cooler canopy appeared to be of less significance under moderate droughts in the UK than under severe droughts in other regions worldwide. The value of large stem soluble carbohydrate reserves for drought environments alone could not be confirmed in the UK environment. Stem WSC was positively associated with grain yield under both irrigation and drought. The genetic trait which showed the clearest correlation with the ability to maintain yield under drought was green flag-leaf area persistence. Averaged across years, the positive phenotypic correlation of this trait with yield under drought amongst DH lines of the Beaver × Soissons population (r = 0.49; p ≤ 0.001) indicated the potential use of this trait as a selection criterion for yield under drought. It is suggested that screens for this trait including marker-assisted selection would have value in future breeding programmes aimed at improving yields in high yielding, rainfed environments, but where drought can also be a problem, such as the UK.  相似文献   

7.
Improving irrigation performance is a crucial issue for agriculture and irrigation development in the Lower Mekong River Basin to secure food production for people’s livelihoods. Irrigation efficiency is the most important indicator to determine the performance of an irrigation scheme. This study looks at water management practices and irrigation efficiency in three pilot sites in the Lower Mekong River Basin: the Numhoum scheme in Laos, the Huay Luang scheme in Thailand, and the Komping Pouy scheme in Cambodia. Irrigation efficiency and water productivity were analyzed using a water balance approach at the irrigation scheme level and results in the pilot areas show efficiencies that are definitely higher using this approach than by using the classical concept. Lower water productivity was observed at pilot schemes in areas of single cropping and higher productivity in areas where multiple agricultural activities were practiced. Strict and active water management is required to control and save water to meet agricultural demand and have sufficient water to expand cultivation areas while avoiding shortages. Promoting multiple uses of water for various agricultural activities in command area will increase water productivity.
Hiroshi OkudairaEmail:
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8.
《Field Crops Research》1987,16(1):67-84
The effects of fertilizer and location on the water use of two contrasting varieties of barley were studied in Northern Syria using a neutron probe. The observed patterns of soil moisture dynamics and crop water use were typical of those previously observed in Mediterranean-type environments. Moisture supply, as reflected by rainfall, was the principal factor affecting total water use, but both the application of fertilizer (N and P) and varietal differences also resulted in increased water use, particularly at the wetter location. There were no differences in the water-use efficiency between the two varieties, but the application of fertilizer resulted in large increases of water-use efficiency at both locations. Separation of crop evapotranspiration into crop transpiration and soil evaporation indicated that increased water-use efficiency was partially due to increased transpiration efficiency but was largely due to a reduction in soil evaporative loss, through greater soil shading by the crop canopy, and increased crop transpiration. Examination of this dataset together with the patterns of root and shoot growth suggest that fertilizer and varietal effects on root growth are linked to patterns of water use, growth and yield formation in barley.  相似文献   

9.
This paper examines the trends in water allocation among sectors, water use by source, cropped area, crop production and water productivity. The study was undertaken at two sites in China: the Zhanghe Irrigation District in the Yangtze River Basin approximately 200 km west of Wuhan and Kaifeng City Prefecture located just south of the Yellow River in Henan Province. In both areas, water demand for purposes other than irrigation has grown. In the Zhanghe Irrigation District this resulted in a sharp reduction of water availability for irrigation. The decline of water availability for irrigation resulted in adoption of water saving practices and policies that led to a significant gain in water productivity per unit of irrigation water. In the Kaifeng City Prefecture the increased demand from other uses was met by an increase in groundwater extraction without the dramatic cuts in supplies for agriculture as in the Zhanghe Irrigation District. Gains in water productivity were due almost exclusively to higher crop yields. There will be continuing pressure to further reduce diversions to agriculture from the Zhanghe main reservoir in the Zhanghe Irrigation District and from the Yellow River in Kaifeng. Research continues on testing practices that have the potential for further increasing water productivity, some of the results of which are reported in other papers in this volume.  相似文献   

10.
Hyderabad is one of the fastest growing cities in India. To meet its rapidly expanding water needs, it constructed and began withdrawals from the Singur reservoir, located on a tributary of the Godavari River, in 1991. Administrative rules define allocation of water from the reservoir but prioritize Hyderabad urban needs over much longer established agricultural uses. Furthermore, the agricultural sector receives less water than even these rules allow, and urban withdrawals have changed the quantity and the timing of the water, which is available to agriculture. An increase in groundwater use by farmers may have been one response to these changes, with possible implications for surface and groundwater users further downstream. While proposals have been put forth to compensate the agricultural sector in general and the farmers directly affected by reallocation, for example by improving access to wastewater for irrigation downstream from Hyderabad or by conveying wastewater for irrigation purposes downstream Singur reservoir, compensation has not been implemented to date. The Hyderabad case study clearly highlights the advantages for devising and implementing arrangements to regulate the transfer of water from agriculture to cities, allowing a move from sectoral competition for water to efficient management of a scarce resource.
Mattia CelioEmail:
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11.
Efficient management of water resources in paddy fields requires an understanding of the volume of supplementary water used. However, quantifying the volume is laborious due to the large amount of data that must be collected and analyzed. The purpose of our study was to estimate the volume of supplementary water used in paddy fields, based on several years of available statistical data, and to provide information on how much water can be supplied to paddy fields in each target area. In this study, the lower Mekong River basin of northeast Thailand, Laos, and Cambodia was selected as the study area. In the first step, we used agricultural statistics for each country, rainfall data acquired from the Mekong River Commission Secretariat (MRCS), and the value of virtual water required per unit of rice production. Because several years of data were used for dry season harvested areas and rice production in each country, the supplementary water to paddy fields in each province was calculated using virtual water and rainfall. This method made it possible to estimate changes in supplementary water in each province. Through this study, the supplementary water to paddy fields during the dry season in three countries was approximated from the minimum number of data sets. Moreover, for cases in which it is not possible to procure agricultural water use data for a hydrological model simulation, an alternative solution is proposed.  相似文献   

12.
In order to confirm that the regional function of Kanazawa’s irrigation water is representative of the urban type, and that Shichika’s irrigation water is representative of the rural, the contingent valuation method (CVM) was applied to determine the economic value of the functions aside from agricultural production, that is, the multi-functional roles of the irrigation water. The economic value of the regional function in Kanazawa was significantly lower than in the Shichika area, reflecting a difference in charge for irrigation water and people’s preference or consciousness in urban and rural areas. In urban areas, people tend to place a higher value on ground view, peace of mind and environmental friendliness. In contrast, in rural areas, irrigation water is presently used for domestic purposes. In other words, in urban areas people see water as public goods, while in rural areas the people see water as private goods. In addition, differences in the economic value of each item that was statistically significant for CVM were estimated using the Turnbull model comparing the items approved or rejected by the respondent.  相似文献   

13.
The water resources of the largest river basin in Mexico, the Lerma-Chapala River, are overcommitted by approximately 10%. A multi-state agreement provides for reallocation of water from agricultural use to environmental and municipal uses during periods of water stress as indicated by extreme low water levels in Lake Chapala. In 1999 the level of water in the lake was such that the ecology of the lake was severely threatened. Based on the agreement, 240 million cubic meters of surface water originally intended for irrigation was diverted to the lake. This represented approximately 70% of the surface supply available to the 700,000 ha of irrigation, and approximately 36% of the total supply. No compensation was paid to the irrigators who lost this resource. The over-use of both the surface and groundwater resources suggests that some permanent reallocation of water from agriculture is inevitable. This case study is abstracted and modified from Wester et al. (2001). For a complete exposition of the institutional characteristics and issues, associated with this case, refer to Wester et al. (2005).  相似文献   

14.
Egypt faces great challenges due to its limited water resources by enforcement policies to improve the performance of the existing delivery system and its development. The improvement of irrigation systems in the Nile Delta is one of the most important attempts in Egypt to implement more effective irrigation technologies. This study was carried out to evaluate improved tertiary canal level and farmers’ practices by comparing with other unimproved systems to understand the farmers’ practices in their farms after modifying the existing irrigation system. This study area applied to the Wasat command area’s most commonly used to the cultivation of a paddy field in Egypt, which contributes 40 % of production. The overall results indicate that the water-use application at the improved system level improved. This was due to the role of water user association in the successful management and operation of the water-supply system on the private level of water distribution network. So, water users’ association has the positive effect on managing of the improved tertiary canal. Although, there are main problems of water delivery in the irrigation networks that was a water shortage in the main canal owing to its location at the tail of the feeder canal system in the Nile Delta, and other reasons include the absence of crop production planning by farmers, especially rice farmers in summer, and the greater demand of some fields than supply.  相似文献   

15.
Appropriate benchmarks for water productivity (WP), defined here as the amount of grain yield produced per unit of water supply, are needed to help identify and diagnose inefficiencies in crop production and water management in irrigated systems. Such analysis is lacking for maize in the Western U.S. Corn Belt where irrigated production represents 58% of total maize output. The objective of this paper was to quantify WP and identify opportunities to increase it in irrigated maize systems of central Nebraska. In the present study, a benchmark for maize WP was (i) developed from relationships between simulated yield and seasonal water supply (stored soil water and sowing-to-maturity rainfall plus irrigation) documented in a previous study; (ii) validated against actual data from crops grown with good management over a wide range of environments and water supply regimes (n = 123); and (iii) used to evaluate WP of farmer's fields in central Nebraska using a 3-y database (2005–2007) that included field-specific values for yield and applied irrigation (n = 777). The database was also used to quantify applied irrigation, irrigation water-use efficiency (IWUE; amount of yield produced per unit of applied irrigation), and the impact of agronomic practices on both parameters. Opportunities to improve irrigation management were evaluated using a maize simulation model in combination with actual weather records and detailed data on soil properties and crop management collected from a subset of fields (n = 123). The linear function derived from the relationship between simulated grain yield and seasonal water supply, namely the mean WP function (slope = 19.3 kg ha−1 mm−1; x-intercept = 100 mm), proved to be a robust benchmark for maize WP when compared with actual yield and water supply data. Average farmer's WP in central Nebraska was ∼73% of the WP derived from the slope of the mean WP function. A substantial number of fields (55% of total) had water supply in excess of that required to achieve yield potential (900 mm). Pivot irrigation (instead of surface irrigation) and conservation tillage in fields under soybean–maize rotation had the greatest IWUE and yield. Applied irrigation was 41 and 20% less under pivot and conservation tillage than under surface irrigation and conventional tillage, respectively. Simulation analysis showed that up to 32% of the annual water volume allocated to irrigated maize in the region could be saved with little yield penalty, by switching current surface systems to pivot, improving irrigation schedules to be more synchronous with crop water requirements and, as a fine-tune option, adopting limited irrigation.  相似文献   

16.
Analysis of return flows in a tank cascade system in Sri Lanka   总被引：2，自引：0，他引：2  
In Sri Lanka, irrigation reservoirs (tanks) are usually connected sequentially and form cascades along the landscape. A study was carried out in the Anuradhapura District in the dry zone of Sri Lanka to understand the role of return flows in such tank cascade systems. The water balance of a tank cascade system was estimated using hydrological data collected over a one-year period. The system was extended about 25 km along a river composed of three small reservoirs having the command area of 31, 55, and 55 ha, respectively. In this system, about 46% of seepage water from tanks entered the paddy fields of the command area. The crop consumed part of the water and the rest returned to the downstream tank through the drainage canals. Percolation loss in the command areas was low (3.6 mm/day) since a considerable portion of the percolation returned to the downstream tank. These results showed that return flows, which are generally disregarded in the water budget, contributed considerably to the water supply of the tank cascade system.  相似文献   

17.
In the Hetao Irrigation Districts of the Ningxia autonomous region, Upper Yellow River Basin, the continuous deep flooding irrigation method is used for the rice paddies. The field irrigation water use during the rice-growing season is two to three times higher than in other regions of North China where water-saving practices have been introduced. This paper, based on the data measured in experimental rice fields and sub-branch canal systems, presents main results concerning crop evapotranspiration, percolation and irrigation requirements for deep and shallow water irrigation. Causes for water waste relate to both the lack of regulation in supply and distribution canals and to the poor management of paddy fields. The potential for water saving is discussed using water balance data. Improved irrigation techniques and water management strategies, including the shallow water irrigation method, are suggested considering the expected impacts and benefits. Replacing the current continuous deep flooding with the shallow-ponded water irrigation method may reduce the growing season irrigation water use from 1,405 to 820 mm in average, with a likely increase in yields of 450 kg/ha. Water productivity would then increase from 0.49 to 1.03 kg/m3. Adopting improved canal management and modernization of regulation and control structures may lead to decreasing the gross irrigation demand from the present 3,100 mm to about 1,280 mm, which would highly benefit the environmental conditions in the area.  相似文献   

18.
River water and groundwater are used to irrigate paddy fields and are also principal sources of drinking water for humans. It is important to understand the transport characteristics of water (e.g., direction and intensity of water flow), when grasping a pollution situation in the soil. Endo and Hara (Soc Inst Contr Eng Trans Ind App 2:88–95, 2003) developed the Quintuple-Probe Heat-Pulse (QPHP) sensor to identify water flux density vectors and thermal properties under saturated and steady state conditions. However, there has not yet been any investigation of moisture transfer under transient conditions such as during internal drainage and mid-summer drainage of paddy fields. Only Sand has been used in previous experiments, and examinations with Loamy and Clayey soils have not yet led to done. Simultaneous measurements of the water flux density vectors and thermal properties of soil texture of three types under drainage conditions as well as the soil moisture transfer analysis with Finite Element Method (FEM), were done. The representative drainage flow was indicated as downward, except in the Sandy-Clayey Loam, in which the rightward flux exceeded the downward flux owing to anisotropy of the soil-pore structure and hydraulic conductivity. The apparent horizontal/vertical advanced distance was introduced in order to know about how water moved through the soil column. The estimated volumetric water content was in good agreement with the measured value. Thus, this measurement method was shown to be valid under transient water flow conditions.  相似文献   

19.
Ba Lai Irrigation Project is located at coastal area in the Mekong Delta. In dry season when the flow rate decreases and the strong east wind blows into the delta, the salinity intrusion increases and seriously affects agricultural and domestic water use. Intakes of Ba Lai system have to be closed for 1–3 months depending on their locations, and no water supply during this period often causes water pollution in the project area. In order to solve such problems, this study aims to seek gate operation procedures for salinity control and water environment improvement. A numerical model is developed to simulate water movement, salinity concentration and duration of remaining water (water age) within the system under three scenarios: (1) without control structures, (2) with available control structures, (3) with the full control structures. Through the numerical simulations, control structures are confirmed to be an effective measure for the salinity control and suitable gate operation schedules are proposed to improve the water environment in the project.  相似文献   

20.
This special issue deals with water and food as it applies to water resources and rice production in the Mekong River Basin. The range of papers reflects not only the broad interest but also the complexity of the topic. These reports are mainly based on the research carried out by the project, “Assessment of the Impact of Global-Scale Change in Water Cycles on Food Production and Alternative Policy Scenarios”. Hence the special issue gives a brief overview of the structure, goals, outcomes, and future direction of the above project. What we do in this paper are: (1) giving an overview of the project’s structure and goals, (2) stating the five common outcomes and several more specific results, and (3) looking forward to the future direction of the project. The aim of our research is to draw up scenarios for optimum water-resource distribution and to develop social guidelines, measures, and policies to help solving food and environmental problems by developing a world water–food model that emphasizes rice production in Monsoon Asia. We have integrated all of the data gathered and the research results into a food supply and demand model combined with a water-cycle analysis. We included operational factors, such as water-cycle change, water demand, water supply, and water distribution in the model. Emphasis is placed on the use of efficient resource-management technologies for proper use of water resources in agricultural and other sectors. The water–food model has been developed as a tool for evaluating technical decisions derived under various policy scenarios.  相似文献   

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