POST-PRINT VERSION AbstractThe hypothesis of a rebound effect as a consequence of water saving investments is taken analogically from the Jevons paradox models in energy economics. The European Commission (EC) alert about the consequences in water stressed regions that are investing heavily in modernization of irrigation networks and systems. This paper reviews the literature, linking water savings with water diversion and water depletion, both from theoretical models and empirical evidence from the published research. In order to increase knowledge of this phenomenon, a new empirical case study is presented based on a survey of 36,000 ha of recently modernized irrigated areas in the Guadalquivir basin (southern Spain). The results of the case study illustrates the conditions that may avoid rebound effect, although the results of the available empirical evidence and the published theoretical research are diverse and lead to contradictory results. Further research is therefore needed to determine the causes and solutions of water saving investment impacts and the possible speculative rebound effect.Keywords: Water conservation; Jevons paradox; Rebound effect; Water pricing; Water use; Water consumption; Spain Highlights The present study analyzes the theoretical and empirical evidence that water saving investments may lead to increased water use and/or consumption. Some authors suggest that if irrigated land expansion is not constrained, increased water abstractions are likely to occur. When land expansion is constrained and water rights are controlled, water depletion does not increase. The results of published research are diverse and have yielded contradictory results regarding the rebound effect as a consequence of water saving investments.

Ecuador has the highest deforestation rate in South America, causing large‐scale soil erosion. Inter‐Andean watersheds are especially affected by a rapid increase of the population leading to the conversion of large areas of montane forest into pasture and cropland. In this study, we estimate soil erosion risk in a small mixed land‐use watershed in the southern Andes of Ecuador. Soil loss was estimated at a spatial resolution of 30 m, using the Revised Universal Soil Loss Equation (RUSLE) where the RUSLE factors were estimated on the basis of limited public available data. Land‐cover maps for 1976, 2008 and 2040 were created assuming increasing deforestation rates over the ensuing decades. Greater erosion rates are estimated for succession areas with agricultural cropland and pasture with maximum values of 936 Mg ha−1 y−1, where slopes and precipitation amounts are the greatest. Under natural forest vegetation, the estimated soil erosion rates are negligible (1·5 to 40 Mg ha−1 y−1) even at steep slopes and higher elevations where rainfall amounts and intensities are generally higher. When the entire watershed has undergone substantial deforestation in 2040, erosion values may reach 2,021 Mg ha−1 y−1. Vegetation cover is the most important factor for potential soil erosion. Secondary factors are related to rainfall (R‐factor) and topography (LS factors). Although the spatial predictions of potential soil erosion have only limited meaning for erosion risk, this method provides an important screening tool for land management and assessment of land‐cover change. Copyright © 2013 John Wiley & Sons, Ltd.

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In recent years, many modernization processes have been undertaken in irrigation districts with the main objective to improve water use efficiency. In southern Spain, many irrigation districts have either been modernized or are currently being improved. However, as part of the modernization process some unexpected side effects have been observed. This paper analyzes the relative advantages and limitations of modernization based on field data collected in a typical Andalusian irrigation district. Although the amount of water diverted for irrigation to farms has been considerably reduced, consumptive use has increased, mainly due to a change in crop rotations. The costs for operation and system maintenance have dramatically risen (400%) as the energy for pumping pressurized systems is much higher now compared to gravity fed systems used previously. Then a regional analysis in ten Southern Spain irrigation districts of the relationship between energy requirements and irrigation water applied has been carried out. Results show that to apply an average depth of 2590 m 3 ha, the energy required was estimated to be 1000 kWh ha -1 . A new approach is needed that involves efficient management of both water and energy resources in these modernized systems. Finally, some energy saving options are identified and discussed.Additional key words: energy use; performance indicators; pressurized irrigation networks; Spain. ResumenLa paradoja de la modernización de zonas regables: uso más eficiente del agua vinculado al aumento de la demanda energética En los últimos años se han llevado a cabo numerosos procesos de modernización en comunidades de regantes con el principal objetivo de mejorar la eficiencia en el uso del agua. En el sur de España se han modernizado, o están en proceso, muchas comunidades de regantes, pero se han observado efectos diferentes a los previstos. En este trabajo se analizan las ventajas e inconvenientes de la modernización usando datos de campo obtenidos en una comunidad de regantes típica de Andalucía. Aunque la cantidad de agua destinada para el riego de las parcelas se redujo, el uso consuntivo de agua se incrementó, fundamentalmente debido al cambio de cultivos. Los costes de operación y mantenimiento del sistema aumentaron considerablemente (400%) ya que la energía requerida para bombear el agua a la red de presión es muy superior en comparación con la situación anterior. Posteriormente se analiza la relación entre el uso del agua y el consumo energético en diez comunidades de regantes del sur de España. Los resultados muestran que para aplicar una lámina media de 2590 m 3 ha -1 , la energía requerida es de 1000 kWh ha -1 . Por ello, en este tipo de redes, cada vez es más necesario manejar los recursos agua y energía de una manera eficiente. Finalmente se discuten diversas medidas de ahorro energético.Palabras clave adicionales: eficiencia energética; España; indicadores de gestión; redes de riego a presión.

In this paper we propose a new perceptual edge detector based on anisotropic linear filtering and local maximization. The novelty of this approach resides in the mixing of ideas coming both from perceptual grouping and directional recursive linear filtering. We obtain new edge operators enabling very precise detection of edge points which are involved in large structures. This detector has been tested successfully on various image types presenting difficult problems for classical edge detection methods.

Useful for human visual perception, edge detection remains a crucial stage in numerous image processing applications. One of the most challenging goals in contour detection is to operate algorithms that can process visual information as humans require. To ensure that an edge detection technique is reliable, it needs to be rigorously assessed before being used in a computer vision tool. This assessment corresponds to a supervised evaluation process to quantify differences between a reference edge map and a candidate, computed by a performance measure/criterion. To achieve this task, a supervised evaluation computes a score between a ground truth edge map and a candidate image. This paper presents a survey of supervised edge detection evaluation methods. Considering a ground truth edge map, various methods have been developed to assess a desired contour. Several techniques are based on the number of false positive, false negative, true positive and/or true negative points. Other methods strongly penalize misplaced points when they are outside a window centered on a true or false point. In addition, many approaches compute the distance from the position where a contour point should be located. Most of these edge detection assessment methods will be detailed, highlighting their drawbacks using several examples. In this study, a new supervised edge map quality measure is proposed. The new measure provides an overall evaluation of the quality of a contour map by taking into account the number of false positives and false negatives, and the degrees of shifting. Numerous examples and experiments show the importance of penalizing false negative points differently than false positive pixels because some false points may not necessarily disturb the visibility of desired objects, whereas false negative points can significantly change the aspect of an object. Finally, an objective assessment is performed by varying the hysteresis thresholds on contours of real images obtained by filtering techniques. Theoretically, by varying the hysteresis thresholds of the thin edges obtained by filtering gradient computations, the minimum score of the measure corresponds to the best edge map, compared to the ground truth. Twenty-eight measures are compared using different edge detectors that are robust or not robust regarding noise. The scores of the different measures and different edge detectors are recorded and plotted as a function of the noise level in the original image. The plotted curve of a reliable edge detection measure must increase monotonously with the noise level and a reliable edge detector must be less penalized than a poor detector. In addition, the obtained edge map tied to the minimum score of a considered measure exposes the reliability of an edge detection evaluation measure if the edge map obtained is visually closer to the ground truth or not. Hence, experiments illustrate that the desired objects are not always completely visible using ill-suited evaluation measure.

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In recent years, information security has received a great deal of attention. To give an example, steganography techniques are used to communicate in a secret and invisible way. Digital color images have become a good medium for digital steganography because of their easy manipulation as carriers via Internet, e‐mails, or used on websites. The main goal of steganalysis is to detect the presence of hidden messages in a digital media. The proposed method is a further extension of the authors' previous work: steganalysis based on color feature correlation and machine learning classification. Fusing features with those obtained from color‐rich models allows increasing the detectability of hidden messages in the color images. Our new proposition uses two types of features, computed between color image channels. The first type of feature reflects local Euclidean transformations, and the second one reflects mirror transformations. These geometric measures are obtained by the sine and cosine of gradient angles between all the color channels. Features are extracted from co‐occurrence correlation matrices of measures. We demonstrate the efficiency of the proposed framework on three steganography algorithms designed to hide messages in images represented in the spatial domain: S‐UNIWARD, WOW, and Synch‐HILL. For each algorithm, we applied a range of different payload sizes. The efficiency of the proposed method is demonstrated by the comparison with the previous authors work and the spatial color‐rich model and color filter array‐aware features for steganalysis. Copyright © 2016 John Wiley & Sons, Ltd.