Ines Cherif

Integrated Methodology for Estimating Water Use in Mediterranean Agricultural Areas

Agricultural use is by far the largest consumer of fresh water worldwide, especially in the Mediterranean, where it has reached unsustainable levels, thus posing a serious threat to water resources. Having a good estimate of the water used in an agricultural area would help water managers create incentives for water savings at the farmer and basin level, and meet the demands of the European Water Framework Directive. This work presents an integrated methodology for estimating water use in Mediterranean agricultural areas. It is based on well established methods of estimating the actual evapotranspiration through surface energy fluxes, customized for better performance under the Mediterranean conditions: small parcel sizes, detailed crop pattern, and lack of necessary data. The methodology has been tested and validated on the agricultural plain of the river Strimonas (Greece) using a time series of Terra MODIS and Landsat 5 TM satellite images, and used to produce a seasonal water use map at a high spatial resolution. Finally, a tool has been designed to implement the methodology with a user-friendly interface, in order to facilitate its operational use.

Rapid error assessment for quantitative estimations from Landsat 7 gap-filled images

The failure of the Scan Line Corrector (SLC) of the Landsat ETM+ (Enhanced Thematic Mapper Plus) instrument in 2003 had resulted in missing values for 22% of each scene. As the remaining pixels were of high quality, several procedures had been developed to fill the gaps and increase the usability of the SLC-off images. In this letter, a methodology is presented to assess the error when estimating quantitative parameters from gap-filled Landsat 7 images. The error from the gap-filling procedure was estimated using an external reference image. The methodology was applied in a Mediterranean river basin using two types of gap-filling methods and the error was estimated for leaf area index (LAI), actual evapotranspiration (ETa) and soil moisture in the rootzone (SMrz), three remotely sensed products which are commonly used in hydrological studies. The results suggest that the interpolation method had lower errors in all examined products. The proposed methodology is an imperative step that each user of gap-filled products could use to estimate the associated error before using the maps.

Combining remotely sensed surface energy fluxes and GIS analysis of groundwater parameters for irrigation system assessment

Abstract Despite being necessary for effective water management, the assessment of an irrigation system requires a large amount of input data for the estimation of related parameters and indicators, which are seldom measured in a regular and reliable manner. In this work, spatially distributed surface energy balance fluxes and geographical information systems analysis of multiple groundwater parameters were used to estimate water availability, supply, and demand, in order to calculate water-accounting indicators. This methodology was used to evaluate the performance of an irrigation system in the Pinios river basin (Greece) at two selected years of high and low water availability. Time series of archived satellite images and groundwater measurements have been used for past years to support comparative analyses, due to the limited availability of actual water measurements. The resulting maps from the proposed methodology show that the performance of the irrigation system varied across space and time due to differences in its characteristics and changes in its operation, driven by fluctuation of water availability and the response of stakeholders to water depletion. Irrigation districts with unsustainable water management were identified and, together with those with slow and/or limited groundwater recharge, were brought to the attention of water managers. The observed differences in the system operation between the wet and dry years were attributed not only to the hydrological conditions of each year, but also to the changing behaviour of farmers and the improvement actions of the water managers.

A Tracking Framework for Accurate Face Localization

This paper proposes a complete framework for accurate face localization on video frames. Detection and forward tracking are first combined according to predefined rules to get a first set of face candidates. Backward tracking is then applied to provide another set of pos-sible localizations. Finally a dynamic programming algorithm is used to select the candidates that minimize a specific cost function. This method was designed to handle different scale, pose and lighting conditions. The experiments show that it improves the face detection rate compared to a frame-based detector and provides a higher precision than a forward information-based tracker.

Improving remotely sensed actual evapotranspiration estimation with raster meteorological data

Evapotranspiration is a process driven by weather, vegetation, and soil conditions. The complex interrelations among these parameters have been modelled by numerous remote-sensing energy balance algorithms. When estimating evapotranspiration on a regional scale, the spatial variability of the weather parameters is important and thus closer attention to the meteorological input data is required. The aim of this work is to improve the accuracy of estimating actual evapotranspiration by integrating outputs from a meteorological model into a remotely sensed energy balance model. In order to achieve this, a time series of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images were processed to retrieve daily evapotranspiration values using raster meteorological data. The ITA-MyWater tool implementing the ReSET-Raster algorithm was used in the Tâmega trans-boundary watershed shared by Portugal and Spain. The results were compared to the global MODIS evapotranspiration products for validation, achieving a coefficient of correlation of 0.61 and a root mean square error of 0.92 mm day–1. Compared with an actual evapotranspiration map that was generated using weather station data, there were improvements in the spatial distribution, especially in dry areas where differences between evapotranspiration estimations of up to 1.88 mm day–1 were noticed. The proposed methodology contributes to the improved estimation of water use, an important parameter of water cycles, using satellite remote-sensing data.

Shot type identification of movie content

This paper aims at providing a quantitative description of shot types commonly used in movie productions. Only qualitative descriptions are available in the literature and even these are subject to various naming conventions. A vocabulary is fixed and human body-based rules are defined to extract the shot types. A database was generated with a set of samples labeled by cinematography experts. The proposed approach was tested on the set of samples providing promising results.