In a worldwide context of ever-growing competition for water and land, climate change, droughts and man-made water scarcity, and less-participatory water governance, agriculture faces the great ...challenge of producing enough food for a continually increasing population. In this line, this book provides a broad overview of innovation issues in the complex water–agriculture–food nexus, thus also relative to their interconnections and dependences. Issues refer to different spatial scales, from the field or the farm to the irrigation system or the river basin. Multidisciplinary approaches are used when analyzing the relationships between water, agriculture, and food security. The covered issues are quite diverse and include: innovation in crop evapotranspiration, crop coefficients and modeling; updates in research relative to crop water use and saving; irrigation scheduling and systems design; simulation models to support water and agricultural decisions; issues to cope with water scarcity and climate change; advances in water resource quality and sustainable uses; new tools for mapping and use of remote sensing information; and fostering a participative and inclusive governance of water for food security and population welfare. This book brings together a variety of contributions by leading international experts, professionals, and scholars in those diverse fields. It represents a major synthesis and state-of-the-art on various subjects, thus providing a valuable and updated resource for all researchers, professionals, policymakers, and post-graduate students interested in the complex world of the water–agriculture–food nexus.
The Independent Evaluation Group (IEG) of the World Bank has undertaken impact evaluations of the Banks support to irrigation in Andhra Pradesh, India (under AP Irrigation II and III), and of the ...U.K. Department for International Development supported Rural Livelihoods Project (RLP).This is one of a series of IEG impact evaluations (see appendix H). IEGs program of impact evaluation is in part carried out under a Department for International DevelopmentIEG partnership agreement; hence the focus on RLP. However, survey villages are also covered by the Bank supported DPIP project, so that the findings are also relevant to this project.
The replacement of flood‐irrigation systems by drip‐irrigation technology has been widely promoted with the aim of a more sustainable use of freshwater resources in irrigated agriculture. However, ...evidence for an irrigation efficiency paradox emphasizes the need to improve our understanding of the impacts of irrigation transformations on water resources. Here, we developed a distributed hydrological modeling approach to investigate the spatiotemporal effect of flood and drip irrigation on groundwater recharge. The approach recognizes differences in the water balance resulting from the localized application of water in surface drip‐irrigated fields and the more extensive application of water in flood irrigation. The approach was applied to the semi‐arid Mediterranean region of Valencia (Spain) and calibrated using a multi‐objective framework. Multiple process scales were addressed within the framework by considering the annual evaporative index, monthly groundwater level dynamics, and daily soil moisture dynamics. Daily simulations from 1994 to 2015 suggested that, in our hydroclimatic conditions, (a) annual recharge is strongly related to annual rainfall, which had a four times higher impact on recharge than the type of irrigation practice, (b) flood‐irrigated recharge tends to exceed drip‐irrigated recharge by 10% at annual time scales, (c) however, recharge response to a particular precipitation event is smaller in flood irrigation than in drip irrigation, and (d) 8–18 rainfall events could generate more than half of the annual recharge in drip and flood irrigation, respectively. Our results highlight the importance of understanding the hydrological dynamics under different irrigation practices for supporting irrigation infrastructure policies.
Key Points
We developed a modeling approach to simulate the impacts of a transition from flood to drip irrigation on basin scale groundwater recharge
Annual recharge was strongly related to annual rainfall, but to a much smaller extent to irrigation practice
Sensitivity of daily recharge to single precipitation events was stronger in drip irrigation than in flood irrigation
Deficit irrigation practices can reduce water and energy cost, thus potentially increasing water use efficiency and water savings in citrus production. Deficit irrigation management, if timed at ...periods of reduced water demand, can moderate citrus leaf and root flush patterns which could help control pest pressure such as Asian citrus psyllid and trigger increased root water and nutrient uptake and tree growth. Recently, we conducted two experiments to understand the impact of reducing irrigation amounts on water use patterns in 1- to 3-year-old HLB-affected citrus in Florida.
A great challenge for the agricultural sector is to produce more food from less water, particularly in arid and semi-arid regions which suffer from water scarcity. A study was conducted to evaluate ...the effect of three irrigation methods, using effluent versus fresh water, on water savings, yields and irrigation water use efficiency (IWUE). The irrigation scheduling was based on soil moisture and rooting depth monitoring. The experimental design was a split plot with three main treatments, namely subsurface drip (SSD), surface drip (SD) and furrow irrigation (FI) and two sub-treatments effluent and fresh water, which were applied with three replications. The experiment was conducted at the Marvdasht city (Southern Iran) wastewater treatment plant during 2005 and 2006. The experimental results indicated that the average water applied in the irrigation treatments with monitoring was much less than that using the conventional irrigation method (using furrows but based on a constant irrigation interval, without moisture monitoring). The maximum water saving was obtained using SSD with 5907
m
3
ha
−1 water applied, and the minimum water saving was obtained using FI with 6822
m
3
ha
−1. The predicted irrigation water requirements using the Penman–Monteith equation (considering 85% irrigation efficiency for the FI method) was 10,743
m
3
ha
−1. The pressure irrigation systems (SSD and SD) led to a greater yield compared to the surface method (FI). The highest yield (12.11
×
10
3
kg
ha
−1) was obtained with SSD and the lowest was obtained with the FI method (9.75
×
10
3
kg
ha
−1). The irrigation methods indicated a highly significant difference in irrigation water use efficiency. The maximum IWUE was obtained with the SSD (2.12
kg
m
−3) and the minimum was obtained with the FI method (1.43
kg
m
−3). Irrigation with effluent led to a greater IWUE compared to fresh water, but the difference was not statistically significant.
Citrus trees require water to be able to carry out the natural processes of growth, making food, and developing fruit and juice. To get the water from the soil, the fibrous roots do the extraneous ...work of absorbing the water and carrying it via the transpiration stream (or the water highway) to the leaves. The water in the soil is made available through either irrigation or rainfall. In this article, we will focus on how to use soil moisture sensors to determine how much to apply and how to use sensors for irrigation management.
Irrigation system design includes pump sizing and selection, valve sizing and selection, and pipe sizing as well as the proper selection and placement of many other components. Good design involves ...selecting and sizing components to perform their intended tasks within the constraints of the system, to ensure an efficient, cost effective, and durable irrigation system. Cost effectiveness will result when oversizing is avoided. Undersizing of components will cut initial costs but often results in poor irrigation distribution uniformity or the complete or partial failure of the system through ruptured pipes, damaged valves, or pump damage. Like any other moving fluid, flowing water has momentum. When subjected to a sudden change in flow, shock waves propagate through the system. This occurrence is referred to as "water hammer." Flow changes can occur due to operation of valves, starting and stopping of pumps, or directional changes caused by pipe fittings. The intensity of water hammer effects will depend upon the rate of change in the velocity or momentum. This publication discusses the causes of water hammer and the importance of proper system design and management to ensure a cost effective, long-lasting irrigation system.
WinSRFR is a new generation of software for analyzing surface irrigation systems. Founded on an unsteady flow hydraulic model, the software integrates event analysis, design, and operational analysis ...functionalities, in addition to simulation. This paper provides an overview of functionalities, interface, and architectural elements of the software, and discusses technical enhancements in version 2.1, released in late 2007, and version 3.1, scheduled for release in 2009.
There is an emerging understanding toward the importance of land‐atmosphere interactions in the monsoon system, but the effects of specific land and water management practices remain unclear. Here, ...using regional process‐based experiments, we demonstrate that monsoon precipitation is sensitive to the choice of irrigation practices in South Asia. Experiments with realistic representation of unmanaged irrigation and paddy cultivation over north‐northwest India exhibit an increase in the late season terrestrial monsoon precipitation and intensification of widespread extreme events over Central India, consistent with changes in observations. Such precipitation changes exhibit substantially different spatial patterns in experiments with a well‐managed irrigation system, indicating that increase in unmanaged irrigation might be a factor driving the observed changes in the intraseasonal monsoon characteristics. Our findings stress the need for accurate representation of irrigation practices to improve the reliability of earth system modeling over South Asia.
Plain Language Summary
South Asia is one of the most heavily irrigated regions of the world, and a large proportion of the water for irrigation is extracted through groundwater pumping. The major summer crop of the region is paddy, which is cultivated in fields flooded with water. Here we study the impact of this agricultural water use on the Indian Summer Monsoon using a climate model. We find that the excess irrigation over northern India shifts the September month monsoon rainfall toward the northwestern part of the subcontinent. This pattern of change is also visible in recorded rainfall over the region in the recent past. Another major impact we see is on the intensity of extreme rainfall events over the central part of the country. Central India has witnessed an increase in extreme rainfall in recent decades, and through this study, we find that irrigation increases the rainfall intensity over Central India during these events. These findings indicate that it is important to represent irrigation practices more accurately in climate models.
Key Points
Representation of irrigation and paddy fields is added to a regional climate model to study that impacts on Indian Summer Monsoon
Excess irrigation over northern India causes northwestward shift in September month monsoon rainfall over the land mass
Irrigation intensifies widespread extreme events over Central India
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