1,720,976 research outputs found
From global goals to local gains—a framework for crop water productivity
Full text linkCrop water productivity (CWP) has become a recognised indicator in assessing the state of Sustainable Development Goals (SDG) 6.4—to substantially increase water use efficiency. This indicator, while useful at a global scale, is not comprehensive at a local scale. To fill this gap, this research proposes a CWP framework, that takes advantage of the spatio-temporal availability of remote sensing, that identifies CWP goals and sub-indicators specific to the needs of the targeted domain. Three sub-indicators are considered; (i) a global water productivity score (GWPS), (ii) a local water productivity score (LWPS) and (iii) a land and water use productivity score (YWPS). The GWPS places local CWP in the global context and focuses on maximised CWP. The LWPS differentiates yield zones, normalising for potential product, and focuses on minimising water consumption. The YWPS focuses simultaneously on improving land and water productivity equally. The CWP framework was applied to potato in the West Bank, Palestine. Three management practices were compared under each sub-indicator. The case study showed that fields with high and low performance were different under each sub-indicator. The performance associated with different management practices was also different under each sub-indicator. For example, a winter rotation had a higher performance under the YWPS, the fall rotation had a higher performance under the LWPS and under the GWPS there was little difference. The results showed, that depending on the basin goal, not only do the sub-indicators required change, but also the management practices or approach required to reach those basin goals. This highlights the importance of providing a CWP framework with multiple sub-indicators, suitable to basin needs, to ensure that meeting the SDG 6.4 goal does not jeopardise local objectives.Water Resource
Status of accuracy in remotely sensed and in-situ agricultural water productivity estimates: A review
No full textThe scarcity of water and the growing global food demand has fevered the debate on how to increase agricultural production without further depleting water resources. Crop water productivity (CWP) is a performance indicator to monitor and evaluate water use efficiency in agriculture. Often in remote sensing datasets of CWP and its components, i.e. crop yield or above ground biomass production (AGBP) and evapotranspiration (ETa), the end-users and developers are different actors. The accuracy of the datasets should therefore be clear to both users and developers. We assess the accuracy of remotely sensed CWP against the accuracy of estimated in-situ CWP. First, the accuracy of CWP based on in-situ methods, which are assumed to be the user's benchmark for CWP accuracy, is reviewed. Then, the accuracy of current remote sensing products is described to determine if the accuracy benchmark, as set by in-situ methods, can be met with current algorithms. The percentage error of CWP from in-situ methods ranges from 7% to 67%, depending on method and scale. The error of CWP from remote sensing ranges from 7% to 22%, based on the highest reported performing remote sensing products. However, when considering the entire breadth of reported crop yield and ETa accuracy, the achievable errors propagate to CWP ranges of 74% to 108%. Although the remote sensing CWP appears comparable to the accuracy of in-situ methods in many cases, users should determine whether it is suitable for their specific application of CWP
Water Productivity of Irrigated Wheat and Maize in the Karkheh River Basin of Iran
No full textThe Karkheh River Basin (KRB) is the third largest and most productive river basin of Iran. The major agricultural issue of the KRB is low water use efficiencies. Farmers' irrigation practices are aimed at maximizing crop production through excessive use of irrigation water resulting in huge water losses. As the opportunities for water resources development in the KRB are very limited, improving the productivity of existing water resources is the most attractive option to produce more food for the increasing population. This paper analyses water productivity of irrigated wheat and maize in the KRB. The results reveal that farmers having access to groundwater tend to apply higher irrigation amounts. Relatively higher crop yields in irrigated areas are also linked to higher nitrogen use, which might create serious problems of groundwater contamination in the future. Due to excessive use of groundwater and fertilizer, production costs have increased, resulting in low gross margins (farm incomes). The study suggests that an increase in charges for surface water use and removal of subsidies on electricity will discourage excessive use of water for agriculture. Furthermore, farmers should be trained to optimize irrigation water and fertilizer application in order to save scarce water resources and reduce production costs and increase farm returns. These steps are of great importance for ensuring sustainability of irrigated agriculture and to alleviate poverty in rural areas of the KRB
Water accounting plus for water resources reporting and river planning. [PhD thesis funded by IWMI through the CGIAR Research Programme on Water Land and Ecosystems]
No full textInfluence of Spatial Resolution on Remote Sensing-Based Irrigation Performance Assessment Using WaPOR Data
Full text linkThis paper analyses the effect of the spatial assessment scale on irrigation performance indicators in small and medium-scale agriculture. Three performance indicators-adequacy (i.e., sufficiency of water use to meet the crop water requirement), equity (i.e., fairness of irrigation distribution), and productivity (i.e., unit of physical crop production/yield per unit water consumption)-are evaluated in five irrigation schemes for three spatial resolutions-250 m, 100 m, and 30 m. Each scheme has varying plot sizes and distributions, with average plot sizes ranging from 0.2 ha to 13 ha. The datasets are derived from the United Nations Food and Agricultural Organization (FAO) water productivity through open access of remotely sensed-derived data (the Water Productivity Open Access Portal-WaPOR) database. Irrigation indicators performed differently in different aspects; for adequacy, all three resolutions show similar spatial trends for relative evapotranspiration (ET) across levels for all years. However, the estimation of relative ET is often higher at higher resolution. In terms of equity, all resolutions show similar inter-annual trends in the coefficient of variation (CV); higher resolutions usually have a higher CV of the annual evapotranspiration and interception (ETIa) while capturing more spatial variability. For productivity, higher resolutions show lower crop water productivity (CWP) due to higher aboveground biomass productivity (AGBP) estimations in lower resolutions; they always have a higher CV of CWP. We find all resolutions of 250 m, 100 m, and 30 m suitable for inter-annual and inter-scheme assessments regardless of plot size. While each resolution shows consistent temporal trends, the magnitude of the trend in both space and time is smoothed by the 100 m and 250 m resolution datasets. This frequently results in substantial differences in the irrigation performance assessment criteria for inter-plot comparisons; therefore, 250 m and 100 m are not recommended for inter-plot comparison for all plot sizes, particularly small plots (<2 ha). Our findings highlight the importance of selecting the spatial resolution appropriate to scheme characteristics when undertaking irrigation performance assessment using remote sensing
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Sand storage dams in Kitui – Kenya: community perspective on access to water: An evaluation using Q-methodology
No full textEphemeral rivers are common hydrological features in Southern Africa where periods of up to 9 months occur, without significant rainfall. These rivers are important in the Kitui region of Kenya, where water shortage impedes rural and urban development. The seasonal rivers of Kitui provide suitable water for domestic, livestock and agricultural use, particularly small-scale irrigation. A majority of the population of Kitui county depends on the ephemeral river for water supply. In dry periods, water levels drop and water can only be found in scoop holes (holes dug in the riverbed). The water shortage is where NaBWIG, an abbreviation for Nature-based water infrastructures in Ethiopia and Kenya for #GlobalGoals (NaBWIG), focuses on. Its goal is to increase resilience through sustainable water supply with the use of stored water within ephemeral sand rivers (Karimi, 2018). This research is part of NaBWIG where, based on 2 months fieldwork trip to Kenya, an evaluation was done using Q-methodology. This study aimed to define which elements of water access are valued by people who use water from sand storage dams in two sub-regions in Kitui – Kenya. This research revealed the broad definition of access to water, specifically when zooming in to local sand dam utilization. Main elements that seem to be most important like distance, time, water quantity, water quality and also reliability of a water source. Other elements are also related to water access such as social capital, income and terrain. Results suggest that ‘one community’ does not exist in either of the regions. The results from the Q-method show different perspectives within both communities on both domestic and agricultural water use, with specifics of perspectives depending on whether one takes the respondents as a whole or analyses them per community. In both regions, comparable elements arise, but different groups appear too. These two ‘communities’ are diverse in perspectives and one must look at both regions with different ‘lenses’ as their position is different from each other. The researcher may force these people into groups, which then are called a community, but in reality, is still a group of people with different interests. The alignment of these different factor groups is important to ensure the community benefit the most of a sand dam structure, which does not stop after construction. This research aimed at creating a better understanding of the interplay of multiple factors regarding water access and provided a more thorough understanding of the dynamics of local communities and their appreciation of water access regarding sand storage dams.Water Managemen
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