Global irrigation water demand: Variability and uncertainties arising from agricultural and climate data sets

Agricultural water use accounts for around 70% of the total water that is withdrawn from surface water and groundwater. We use a new, gridded, global-scale water balance model to estimate interannual variability in global irrigation water demand arising from climate data sets and uncertainties arising from agricultural and climate data sets. We used contemporary maps of irrigation and crop distribution, and so do not account for variability or trends in irrigation area or cropping. We used two different global maps of irrigation and two different reconstructions of daily weather 1963–2002. Simulated global irrigation water demand varied by ∼30%, depending on irrigation map or weather data. The combined effect of irrigation map and weather data generated a global irrigation water use range of 2200 to 3800 km3 a−1. Weather driven variability in global irrigation was generally less than ±300 km3 a−1, globally (\u3c∼10%), but could be as large as ±70% at the national scale

Groundwater use for irrigation - a global inventory

Irrigation is the most important water use sector accounting for about 70% of the global freshwater withdrawals and 90% of consumptive water uses. While the extent of irrigation and related water uses are reported in statistical databases or estimated by model simulations, information on the source of irrigation water is scarce and very scattered. Here we present a new global inventory on the extent of areas irrigated with groundwater, surface water or non-conventional sources, and we determine the related consumptive water uses. The inventory provides data for 15 038 national and sub-national administrative units. Irrigated area was provided by census-based statistics from international and national organizations. A global model was then applied to simulate consumptive water uses for irrigation by water source. Globally, area equipped for irrigation is currently about 301 million ha of which 38% are equipped for irrigation with groundwater. Total consumptive groundwater use for irrigation is estimated as 545 km3 yr−1, or 43% of the total consumptive irrigation water use of 1 277 km3 yr−1. The countries with the largest extent of areas equipped for irrigation with groundwater, in absolute terms, are India (39 million ha), China (19 million ha) and the United States of America (17 million ha). Groundwater use in irrigation is increasing both in absolute terms and in percentage of total irrigation, leading in places to concentrations of users exploiting groundwater storage at rates above groundwater recharge. Despite the uncertainties associated with statistical data available to track patterns and growth of groundwater use for irrigation, the inventory presented here is a major step towards a more informed assessment of agricultural water use and its consequences for the global water cycle

Water distribution rules and water distribution performance: a case study in the Tambraparani Irrigation System

Irrigation management / Irrigation systems / Performance / Irrigation operation / Irrigation scheduling / Water distribution / Water allocation / Water delivery / Water users' associations / Legislation / Large-scale systems / Bananas / Case studies / India / Tamil Nadu / Tambraparani Irrigation System

A Tool for the Evaluation of Irrigation Water Quality in the Arid and Semi-Arid Regions

In the Mediterranean arid and semi-arid regions, large amounts of low quality waters could be used for crop irrigation, but the adoption of articulated classifications with too rigid quality limits can often reduce the recoverable quantities of water and make the monitoring of water quality too much expensive. Therefore, an evaluation of irrigation water quality based on only a few crucial parameters, which consider the crop species to be irrigated and the type of irrigation system and management adopted, can be an easy and flexible method for maximizing the reuse of wastewater and low-quality water for agricultural purposes. In this view, an irrigation water quality tool (IWQT) was developed to support farmers of arid and semi-arid regions on evaluating the use of low quality water for crop irrigation. The most significant and cheapest parameters of irrigation water quality were identified and clustered in three quality classes according to their effects on crop yield and soil fertility (agronomic quality indicators), human health (hygiene and health quality indicators), and irrigation systems (management quality indicators). According to IWQT parameters, a tool reporting a series of recommendations, including water treatment types, was implemented to guide farmers on the use of low quality irrigation water

Effect of Deficit Irrigation on Yield and Water Use Efficiency of Maize at Selekleka District, Ethiopia

Irrigation water availability is diminishing in many areas of the Ethiopian regions, which require many irrigators to consider deficit-irrigation strategy. This study investigated the response of maize (Zea mays L.) to moisture deficit under conventional, alternate and fixed furrow irrigation systems combined with three irrigation amounts over a two years period. The field experiment was conducted at Selekleka Agricultural Research Farm of Shire-Maitsebri Agricultural Research Center. A randomized complete block design (RCBD) with three replications was used. Irrigation depth was monitored using a calibrated 2-inch throat Parshall flume. The effects of the treatments were evaluated in terms of grain yield, dry above-ground biomass, plant height, cob length and water use efficiency. The two years combined result indicated that  net irrigation water applied in alternate furrow irrigation with full amount irrigation depth (100% ETc AFI) treatments was half (3773.5 m3/ha) than that of applied to the conventional furrow with full irrigation amount (CFI with 100% ETc) treatments (7546.9 m3/ha). Despite the very significant reduction in irrigation water used with alternate furrow irrigation (AFI), there was insignificant grain yield reduction in maize(8.31%) as compared to control treatment (CFI with100% ETc). In addition, we also obtained significantly (p<0.001) higher crop water use efficiency of 1.889 kg/m3 in alternate furrow irrigation (AFI), than that was obtained as 0.988 kg/m3 in conventional furrow irrigation (CFI). In view of the results, alternate furrow irrigation method (AFI) is taken as promising for conservation of water (3773.5 m3/ha), time (23:22\u2750" hours/ha), labor (217.36 USD/ha) and fuel (303.79 USD/ha) for users diverting water from the source to their fields using pump without significant trade-off in yield

Pro-poor intervention strategies in irrigated agriculture in Asia: poverty in irrigated agriculture: issues and options: Pakistan

Irrigated farming / Poverty / Irrigation management / Irrigation systems / Water policy / Water rights / Water law / Irrigation scheduling / Organizations / Social aspects / Households / Economic aspects / Expenditure / Irrigation programs / Performance evaluation / Water delivery / Equity / Models / Crop production / Productivity / Wheat / Pakistan

Irrigation and water resources in Latin America and the Caribbean: challenges and strategies

Latin America and the Caribbean are relatively well endowed with water resources. However, population growth and rapid urbanization are putting considerable pressure on water available for irrigation. Local and regional water scarcity problems are exacerbated by severe water quality problems; and wastewater is frequently used for irrigation. Moreover, prospects for new investments into irrigation development appear limited. This paper examines the factors underlying irrigation development in Latin America and the Caribbean, reviews the water supply situation, and describes trends in water demand and irrigated agriculture. The overall water management in the region is assessed, and recent trends in investments in the water sector, with a focus on large-scale irrigation systems, are analyzed. The paper concludes that in this context of accelerating demand and declining irrigation investments, new water development is not the primary solution to water resource challenges in the region. Much greater attention is needed on water policy and management reform to improve the efficiency and equity of irrigation and water supply systems.Water resources development Caribbean Area., Water-supply., Water use Management., Irrigation farming.,

Hydraulic simulations to evaluate and predict design and operation of the Chashma Right Bank Canal

Irrigation systems / Irrigation canals / Flow control / Velocity / Canal regulation techniques / Hydraulics / Simulation models / Design / Operations / Crop-based irrigation / Distributary canals / Water delivery / Policy / Protective irrigation / Water allocation / Water requirements / Sedimentation / Water distribution / Equity / Water conveyance / Pakistan / Chashma Right Bank Canal

Making irrigation management pro-poor: lessons from China and Vietnam

Irrigation management / Poverty / Irrigation systems / Water delivery / Participatory management / Farmer participation / Institutions / Water users’ associations / Water rates / China / Vietnam / Nam Duong Irrigation System / Ningxia Province / Qingtongxia Irrigation District

Root Zone Sensors for Irrigation Management in Intensive Agriculture

Crop irrigation uses more than 70% of the world’s water, and thus, improving irrigation efficiency is decisive to sustain the food demand from a fast-growing world population. This objective may be accomplished by cultivating more water-efficient crop species and/or through the application of efficient irrigation systems, which includes the implementation of a suitable method for precise scheduling. At the farm level, irrigation is generally scheduled based on the grower’s experience or on the determination of soil water balance (weather-based method). An alternative approach entails the measurement of soil water status. Expensive and sophisticated root zone sensors (RZS), such as neutron probes, are available for the use of soil and plant scientists, while cheap and practical devices are needed for irrigation management in commercial crops. The paper illustrates the main features of RZS’ (for both soil moisture and salinity) marketed for the irrigation industry and discusses how such sensors may be integrated in a wireless network for computer-controlled irrigation and used for innovative irrigation strategies, such as deficit or dual-water irrigation. The paper also consider the main results of recent or current research works conducted by the authors in Tuscany (Italy) on the irrigation management of container-grown ornamental plants, which is an important agricultural sector in Italy