Dr Belen Marti-Cardona PhD MSc MEng CICCP


Biography

Areas of specialism

Remote sensing; Hydrological and hydraulic modelling; Water Resources Sustainability

University roles and responsibilities

  • Lecturer in Water Resources Management and Hydraulic Modelling (ENGM057)
  • Lecturer in GIS and Remote Sensing (ENGM285)
  • Lecturer in Environmental Engineering and Hydrology (ENG3177)
  • Lecturer in Hydraulics and Environmental Quality (ENG2101)

    My qualifications

    PhD MSc MEng CICCP

    Research projects

    My publications

    Publications

    MATTHEW NIGEL LAWTON, BELEN MARTI-CARDONA, ALEX HIDDE HAGEN-ZANKER (2021)Urban Growth Derived from Landsat Time Series using Harmonic Analysis: a Case Study in South England with High Levels of Cloud Cover, In: Remote Sensing13(16)3339 MDPI

    Accurate detection of spatial patterns of urban growth is crucial to the analysis of urban growth processes. A common practice is to use post-classification change analysis, overlaying multiple independently derived land cover layers. This approach is problematic as propagation of classification errors can lead to overestimation of change by an order of magnitude. This paper contributes to the growing literature on change classification using pixel-based time series analysis. In particular, we have developed a method that identifies change in the urban fabric at the pixel level based on breaks in the seasonal and year-on-year trend of the normalised difference vegetation index (NDVI). The method is applied to a case study area in the south of England that is characterised by high levels of cloud cover. The study uses the Landsat data archive over the period 1984–2018. The performance of the method was assessed using 500 ground truth points. These points were randomly selected and manually assessed for change using high-resolution earth observation imagery. The method identifies pixels where a land cover change occurred with a user’s accuracy of change 45.3 ± 4.45% and outperforms a post-classification analysis of an otherwise more advanced land cover product, which achieved a user’s accuracy of 17.8 ± 3.42%. This method performs better where changes exhibit large differences in NDVI dynamics amongst land cover types, such as the transition from agricultural to suburban, and less so where small differences of NDVI are observed, such as changes in land cover within pixels that are densely built up already. The method proved relatively robust for outliers and missing data, for example, in the case of high levels of cloud cover, but does rely on a period of data availability before and after the change event. Future developments to improve the method are to incorporate spectral information other than NDVI and to consider multiple change events per pixel over the analysed period.

    V Ruiz-Villanueva, E Bladé, M Sánchez-Juny, B Marti-Cardona, A Díez-Herrero, JM Bodoque (2014)Two-dimensional numerical modeling of wood transport, In: Journal of Hydroinformatics16(5)pp. 1077-1096 IWA Publishing

    The transport of wood material in rivers has been the subject of various studies in recent years. Most research has focused on the ecological and geomorphologic role of wood, its recruitment processes and spatial distribution in streams. In this study, we focused on wood transport dynamics, and we have developed a numerical model to simulate wood transport coupled with a two-dimensional (2D) hydrodynamic model. For this purpose, wood drag forces were incorporated as additional source terms into the shallow water equations, which are solved together with wood transport by using the finite volume method. This new tool has been implemented as a computational module into ‘Iber’, a 2D hydraulic simulation software. The new module analyzes the initial motion threshold of wood based on the balance of forces involved in the wood’s movement, and computes the position and velocity of differently shaped logs using a kinematic approach. The method also considers the interaction between the logs themselves and between the logs and the channel walls or boundaries. Flume experiments were used in a straight channel with obstructions to validate the model’s capacity to accurately reproduce the movement of floating logs

    Belen Marti-Cardona, Jord Prats, Raquel Niclòs (2019)Enhancing the retrieval of stream surface temperature from Landsat data, In: Remote Sensing of Environment224pp. 182-191 Elsevier

    Thermal images of water bodies often show a radiance gradient perpendicular to the banks. This effect is frequently due to mixed land and water thermal pixels. In the case of the Landsat images, radiance mixing can also affect pure water pixels due the cubic convolution resampling of the native thermal measurements. Some authors recommended a general-purpose margin of two thermal pixels to the banks or a minimum river width of three pixels, to avoid near bank effects in water temperature retrievals. Given the relatively course spatial resolution of satellite thermal sensors, the three pixel margin severely restricts their application to temperature mapping in many rivers. This study proposes a new algorithm to enhance the retrieval of stream surface temperature using Landsat 8 thermal data, although it is also applicable to Landsat 7 and Landsat 5. The aim is not to perform a subpixel radiance unmixing but to refine the selection of unmixed, reliable pixels for temperature mapping. For this purpose, the spatial arrangement of native Landsat thermal pixels is approximated, and pure water pixels in the downscaled thermal band are selected accordingly. The least-favourable cubic convolution near-bank radiance mixing is simulated on image basis. Only pure thermal water pixels unaffected by the simulated worstcase resampling are selected. The algorithm allowed retrieving water surface temperature in reaches down to 120m wide, clearly improving the existing three pixel, i.e. 300m for Landsat 8, recommendation. The enhancing algorithm was applied to a reach in the Ebro River reach, Spain. It provided spatially distributed temperatures in narrow parts, upstream and downstream of a wide reservoir, offering new insight of the overall impact of the reservoir over the river thermal regime.

    Ramiro Pillco Zolá, Lars Bengtsson, Ronny Berndtsson, Belen Marti-Cardona, Frederic Satgé, Franck Timouk, Marie-Paule Bonnet, Luis Mollericon, Cesar Gamarra, José Pasapera (2018)Modelling Lake Titicaca's daily and monthly evaporation, In: Hydrology and Earth System Sciences23(2)pp. 657-668 Copernicus Publications

    Lake Titicaca is a crucial water resource in the central part of the Andean mountain range, and it is one of the lakes most affected by climate warming. Since surface evaporation explains most of the lake’s water losses, reliable estimates are paramount to the prediction of global warming impacts on Lake Titicaca and to the region’s water resource planning and adaptation to climate change. Evaporation estimates were done in the past at monthly time steps and using the four methods as follows: water balance, heat balance, and the mass transfer and Penman’s equations. The obtained annual evaporation values showed significant dispersion. This study used new, daily frequency hydrometeorological measurements. Evaporation losses were calculated following the mentioned methods using both daily records and their monthly averages to assess the impact of higher temporal resolution data in the evaporation estimates. Changes in the lake heat storage needed for the heat balance method were estimated based on the morning water surface temperature, because convection during nights results in a well-mixed top layer every morning over a constant temperature depth. We found that the most reliable method for determining the annual lake evaporation was the heat balance approach, although the Penman equation allows for an easier implementation based on generally available meteorological parameters. The mean annual lake evaporation was found to be 1700mmyearˉ¹. This value is considered an upper limit of the annual evaporation, since the main study period was abnormally warm. The obtained upper limit lowers by 200mmyearˉ¹, the highest evaporation estimation obtained previously, thus reducing the uncertainty in the actual value. Regarding the evaporation estimates using daily and monthly averages, these resulted in minor differences for all methodologies.

    Juan Torres-Batlló, Belen Marti-Cardona (2020)Precipitation trends over the Southern Andean Altiplano from 1981 to 2018, In: Journal of Hydrology125485 Elsevier

    This study undertakes a spatio-temporal assessment of the annual and seasonal precipitation trends over the Desaguadero-Poopó (DP) system in Bolivia for the period 1981-2018. Given the insufficient spatial density of meteorological stations in the study, the high-spatial resolution Climate Hazards group Infrared Precipitation with Stations (CHIRPS) satellite product was used. CHIRPS precipitation data was validated against 7,636 gauge measurements and used to map the spatial distribution of precipitation trends. In addition, the temporal changes in the onset, duration and average intensity of the wet season were explored. Results showed a good, statistically significant agreement between CHIRPS data and onsite records of monthly precipitation at the pixel and regional scales. The spatio-temporal precipitation assessment revealed that statistically significant increases in annual precipitation (2– 6 mm yr-1) occurred in two zones at the north and north-western part of the DP system. Only the southern part showed decreasing precipitation trends at a rate of -1 mm yr-1 while the central part did not show significant changes. Overall, a general increasing trend of about 2.5 mm yr-1 was observed for the entire DP system during the 38-year study period, with the months of December and February showing the highest significant increases. The analysis of the onset and cessation times of the rainy season indicated a statistically significant decrease in its duration at a rate of -0.4 day yr-1 and an increment of the average precipitation intensity. Our results reveal trend in the temporal concentration of precipitation in a water scarce region, which highlights the need for the management of the resource, so it can meet societal and environmental demands throughout the year.

    Marcos Sanz-Ramos, Belen Marti-Cardona, Ernest Blade, Irene Seco, Arnau Amengual, Helene Roux, Romu Romero (2020)NRCS-CN Estimation from Onsite and Remote Sensing Data for Management of a Reservoir in the Eastern Pyrenees, In: Journal of Hydrologic Engineering25(9) American Society of Civil Engineers

    Onsite and Earth observation (EO) data are used for the calibration of the Natural Resources Conservation Service curve number (NRCS-CN) value in a hydrological simulation model. The model was developed for La Muga catchment (eastern Pyrenees) highly vulnerable to flood and drought episodes. It is an integral part of a regional reservoir management tool, which aims at minimizing the flood risk while maximizing the preservation of water storage. The CN values were optimized for five recorded events for the model to match the observed hydrographs at the reservoir when supported with the measured rainfall intensities. This study also investigates the possibilities of using antecedent moisture conditions (AMC) retrieved from satellite data to inform the selection of the NRCS-CN losses parameter. A good correlation was found between the calibrated CN values and the AMC obtained from satellite data. This correlation highlights the interest in using EO data to update NRCS-CN estimates. This advances in hydrologic-hydraulic coupled modeling combined with new remote sensing datasets present valuable opportunities and potential benefits for flood risk management and water resources preservation.

    Juan Torres Batlló, Belén Marti-Cardona, Ramiro Pillco-Zolá (2019)Mapping evapotranspiration, vegetation and precipitation trends in the catchment of the shrinking Lake Poopó., In: Remote Sensing12(1)(73) MDPI

    Lake Poopó is located in the Andean Mountain Range Plateau or Altiplano. A general decline in the lake water level has been observed in the last two decades, coinciding roughly with an intensification of agriculture exploitation, such as quinoa crops. Several factors have been linked with the shrinkage of the lake, including climate change, increased irrigation, mining extraction and population growth. Being an endorheic catchment, evapotranspiration (ET) losses are expected to be the main water output mechanism and previous studies demonstrated ET increases using Earth observation (EO) data. In this study, we seek to build upon these earlier findings by analyzing an ET time series dataset of higher spatial and temporal resolution, in conjunction with land cover and precipitation data. More specifically, we performed a spatio-temporal analysis, focusing on wet and dry periods, that showed that ET changes occur primarily in the wet period, while the dry period is approximately stationary. An analysis of vegetation trends performed using 500 MODIS vegetation index products (NDVI) also showed an overall increasing trend during the wet period. Analysis of NDVI and ET across land cover types showed that only croplands had experienced an increase in NDVI and ET losses, while natural covers showed either constant or decreasing NDVI trends together with increases in ET. The larger increase in vegetation and ET losses over agricultural regions, strongly suggests that cropping practices exacerbated water losses in these areas. This quantification provides essential information for the sustainable planning of water resources and land uses in the catchment. Finally, we examined the spatio-temporal trends of the precipitation using the newly available Climate Hazards Group Infrared Precipitation with Stations (CHIRPS-v2) product, which we validated with onsite rainfall measurements. When integrated over the entire catchment, precipitation and ET showed an average increasing trend of 5.2 mm yr−1 and 4.3 mm yr−1, respectively. This result suggests that, despite the increased ET losses, the catchment-wide water storage should have been offset by the higher precipitation. However, this result is only applicable to the catchment-wide water balance, and the location of water may have been altered (e.g., by river abstractions or by the creation of impoundments) to the detriment of the Lake Poopó downstream.

    B. Marti-Cardona, L. Pipia, E. Rodríguez-Máñez, H. Sánchez-Tueros (2017)Teledetección de la evapotranspiración y cambio de cubiertas en la cuenca del Río Locumba, Perú, In: Procedings of XXVII Congreso Latinoamericano de Hidráulica, IAHRpp. 940-941

    Los humedales de alta montaña conocidos como bofedales constituyen un hábitat indispensable para numerosas especies, entre las que se encuentran los camélidos. En las últimas décadas se ha observado la recesión de algunos bofedales y lagunas andinas. En la cuenca del rio Locumba, Perú, se ha postulado que esta recesión puede estar ligada al consumo de los recursos hídricos para usos agrícolas y mineros. El estudio que aquí se presenta utiliza imágenes satelitales para determinar la superficie de agua en las principales lagunas naturales, así como el área ocupada por los bofedales y la superficie agrícola,desde la década de los 70 hasta la actualidad. La tarea incluye además el cómputo de la evapotranspiración real en las áreas cultivadas de la cuenca a partir de dos imágenes recientes correspondientes a los períodos seco y húmedo. La teledetección aporta de este modo una serie histórica de datos espaciales cuantitativos de gran valor para determinar la variación de cubiertas naturales e investigar sus causas.

    B. Marti-Cardona, J. Prats (2018)Reservoir Thermal Impact Captured by Satellite Images, In: Proceedings of the 5th IAHR Europe Congress - New Challenges in Hydraulic Research and Engineeringpp. 439-440 Research Publishing, Singapore

    We used Landsat 8 thermal images to study the longitudinal patterns of surface water temperature in the Mequinenza reservoir, Spain, in 2016. We also estimated its thermal impact on the river by comparing upstream and downstream temperatures.

    Prashant Kumar, Sisay E Debele, Jeetendra Sahani, Nidhi Rawat, Belen Marti-Cardona, Silvia Maria Alfieri, Bidroha Basu, Arunima Sarkar Basu, Paul Bowyer, Nikos Charizopoulos, Juvonen Jaakko, Michael Loupis, Massimo Menenti, Slobodan B Mickovski, Jan Pfeiffer, Francesco Pilla, Julius Pröll, Beatrice Pulvirenti, Martin Rutzinger, Srikanta Sannigrahi, Christos Spyrou, Heikki Tuomenvirta, Zoran Vojinovic, Thomas Zieher (2021)An overview of monitoring methods for assessing the performance of nature-based solutions against natural hazards, In: Earth-science Reviews217103603 Elsevier B.V

    To bring to fruition the capability of nature-based solutions (NBS) in mitigating hydro-meteorological risks (HMRs) and facilitate their widespread uptake require a consolidated knowledge-base related to their monitoring methods, efficiency, functioning and the ecosystem services they provide. We attempt to fill this knowledge gap by reviewing and compiling the existing scientific literature on methods, including ground-based measurements (e.g. gauging stations, wireless sensor network) and remote sensing observations (e.g. from topographic LiDAR, multispectral and radar sensors) that have been used and/or can be relevant to monitor the performance of NBS against five HMRs: floods, droughts, heatwaves, landslides, and storm surges and coastal erosion. These can allow the mapping of the risks and impacts of the specific hydro-meteorological events. We found that the selection and application of monitoring methods mostly rely on the particular NBS being monitored, resource availability (e.g. time, budget, space) and type of HMRs. No standalone method currently exists that can allow monitoring the performance of NBS in its broadest view. However, equipments, tools and technologies developed for other purposes, such as for ground-based measurements and atmospheric observations, can be applied to accurately monitor the performance of NBS to mitigate HMRs. We also focused on the capabilities of passive and active remote sensing, pointing out their associated opportunities and difficulties for NBS monitoring application. We conclude that the advancement in airborne and satellite-based remote sensing technology has signified a leap in the systematic monitoring of NBS performance, as well as provided a robust way for the spatial and temporal comparison of NBS intervention versus its absence. This improved performance measurement can support the evaluation of existing uncertainty and scepticism in selecting NBS over the artificially built concrete structures or grey approaches by addressing the questions of performance precariousness. Remote sensing technical developments, however, take time to shift toward a state of operational readiness for monitoring the progress of NBS in place (e.g. green NBS growth rate, their changes and effectiveness through time). More research is required to develop a holistic approach, which could routinely and continually monitor the performance of NBS over a large scale of intervention. This performance evaluation could increase the ecological and socio-economic benefits of NBS, and also create high levels of their acceptance and confidence by overcoming potential scepticism of NBS implementations.

    Prashant Kumar, Sisay E Debele, Jeetendra Sahani, Nidhi Rawat, Belen Marti-Cardona, Silvia Maria Alfieri, Bidroha Basu, Arunima Sarkar Basu, Paul Bowyer, Nikos Charizopoulos, Glauco Gallotti, Juvonen Jaakko, Laura S Leo, Michael Loupis, Massimo Menenti, Slobodan B Mickovski, Seung-Jae Mun, Alejandro Gonzalez-Ollauri, Jan Pfeiffer, Francesco Pilla, Julius Pröll, Martin Rutzinger, Marco Antonio Santo, Srikanta Sannigrahi, Christos Spyrou, Heikki Tuomenvirta, Thomas Zieher (2021)Nature-based solutions efficiency evaluation against natural hazards: Modelling methods, advantages and limitations, In: The Science of the total environment784147058 Elsevier B.V

    Nature-based solutions (NBS) for hydro-meteorological risks (HMRs) reduction and management are becoming increasingly popular, but challenges such as the lack of well-recognised standard methodologies to evaluate their performance and upscale their implementation remain. We systematically evaluate the current state-of-the art on the models and tools that are utilised for the optimum allocation, design and efficiency evaluation of NBS for five HMRs (flooding, droughts, heatwaves, landslides, and storm surges and coastal erosion). We found that methods to assess the complex issue of NBS efficiency and cost-benefits analysis are still in the development stage and they have only been implemented through the methodologies developed for other purposes such as fluid dynamics models in micro and catchment scale contexts. Of the reviewed numerical models and tools MIKE-SHE, SWMM (for floods), ParFlow-TREES, ACRU, SIMGRO (for droughts), WRF, ENVI-met (for heatwaves), FUNWAVE-TVD, BROOK90 (for landslides), TELEMAC and ADCIRC (for storm surges) are more flexible to evaluate the performance and effectiveness of specific NBS such as wetlands, ponds, trees, parks, grass, green roof/walls, tree roots, vegetations, coral reefs, mangroves, sea grasses, oyster reefs, sea salt marshes, sandy beaches and dunes. We conclude that the models and tools that are capable of assessing the multiple benefits, particularly the performance and cost-effectiveness of NBS for HMR reduction and management are not readily available. Thus, our synthesis of modelling methods can facilitate their selection that can maximise opportunities and refute the current political hesitation of NBS deployment compared with grey solutions for HMR management but also for the provision of a wide range of social and economic co-benefits. However, there is still a need for bespoke modelling tools that can holistically assess the various components of NBS from an HMR reduction and management perspective. Such tools can facilitate impact assessment modelling under different NBS scenarios to build a solid evidence base for upscaling and replicating the implementation of NBS. [Display omitted]

    Ramiro Pillco Zolá, Lars Bengtsson, Ronny Berndtsson, Belen Marti-Cardona, Frederic Satgé, Franck Timouk, Marie-Paule Bonnet, Luis Mollericon, Cesar Gamarra, José Pasapera (2019)Modeling Lake Titicaca Daily and Monthly Evaporation, In: HYDROLOGY AND EARTH SYSTEM SCIENCES COPERNICUS GESELLSCHAFT MBH

    Lake Titicaca is an important water ecosystem of South America. Due to uncertainties in estimating the evaporation losses from the lake, surface water storage calculations are uncertain. In this paper, we try to improve evaporation loss estimations by comparing different methods to calculate daily and monthly evaporation from Lake Titicaca. These were: water balance, heat balance, mass transfer method, and the Penman equation. The evaporation was computed at daily time step and compared with estimated evaporation using mean monthly meteorological observations. We found that the most reliable method of determining the annual lake evaporation is using the heat balance approach. To estimate the monthly lake evaporation using heat balance, the heat storage changes must be known in advance. Since convection from the surface layer is intense during nights resulting in a well-mixed top layer every morning, it is possible to determine the change of heat storage from the measured morning surface temperature. The mean annual lake evaporation was found to be 1700mm. Monthly evaporation computed using daily data and monthly means resulted in minor differences.

    B Marti-Cardona, C López-Martínez, J Dolz-Ripolles (2012)Local texture stationarity indicator for filtering DoÑana wetlands SAR images., In: IGARSSpp. 4903-4906
    B. Marti-Cardona, M. Arbat Bofill, J. Prats, L. Pipia, J. Dolz Ripollés (2015)La teledetección para el estudio del comportamiento térmico de embalses, In: Proceedings of the XVI Congreso de la Asociación Española de Teledetección (AET), Sevilla, Españapp. 374-377 Asociación española de teledetección desde

    ASTER images were used for mapping the water surface temperature in the Mequinenza and the Ribarroja reservoirs, on the Ebro River. The spatially continuous information of these maps reveals the impact of the reservoir on the river’s natural thermal gradient in two different periods of the year. The high spatial resolution images of the Ribarroja reservoir, acquired by the airborne hyperspectral TASI sensor,

    Anaïs Ramos-Fuertes, Belen Marti-Cardona, Ernest Bladé, Josep Dolz (2013)Envisat/ASAR Images for the Calibration of Wind Drag Action in the Doñana Wetlands 2D Hydrodynamic Model, In: Remote Sensing6(1)pp. 379-406 MDPI

    Doñana National Park wetlands are located in southwest Spain, on the right bank of the Guadalquivir River, near the Atlantic Ocean coast. The wetlands dry out completely every summer and progressively flood again throughout the fall and winter seasons. Given the flatness of Doñana’s topography, the wind drag action can induce the flooding or emergence of extensive areas, detectable in remote sensing images. Envisat/ASAR scenes acquired before and during strong and persistent wind episodes enabled the spatial delineation of the wind-induced water displacement. A two-dimensional hydrodynamic model of Doñana wetlands was built in 2006 with the aim to predict the effect of proposed hydrologic restoration actions within Doñana’s basin. In this work, on-site wind records and concurrent ASAR scenes are used for the calibration of the wind-drag modeling by assessing different formulations. Results show a good adjustment between the modeled and observed wind drag effect. Displacements of up to 2 km in the wind direction are satisfactorily reproduced by the hydrodynamic model, while including an atmospheric stability parameter led to no significant improvement of the results. Such evidence will contribute to a more accurate simulation of hypothetic or design scenarios, when no information is available for the atmospheric stability assessment.

    B Marti-Cardona, M Arbat-Bofill, J Prats-Rodríguez, L Pipia (2016)Thermal remote sensing for reservoir modelling and management, In: Proc. ‘Living Planet Symposium 2016’, Prague, Czech Republic, 9–13 May 2016 (ESA SP-740, August 2016)

    ASTER and Landsat images were used for mapping the water surface temperature in the Sobrón, Mequinenza and Ribarroja reservoirs in the Ebro River, Spain. The spatially continuous information in these maps reveals the impact of the reservoir on the river natural thermal gradient in two different periods of the year. It also evidences the thermal impact intensity and extent of the refrigeration flow discharge from a nuclear power plant located on the river bank. The high spatial resolution images of the Ribarroja reservoir, acquired by the airborne hyperspectral TASI sensor, show spatial patterns which complemented the in-situ point measurements and contributed valuable data for validating the three-dimensional thermo-hydrodynamic model of the reservoir.

    Sisay E. Debele, Prashant Kumar, Jeetendra Sahani, Belen Marti-Cardona, Slobodan B. Mickovski, Laura S. Leo, Federico Porcù, Flavio Bertini, Danilo Montesi, Zoran Vojinovic, Silvana Di Sabatino (2019)Nature-based solutions for hydro-meteorological hazards: Revised concepts, classification schemes and databases, In: Environmental Research108799 Elsevier

    Hydro-meteorological hazards (HMHs) have had a strong impact on human societies and ecosystems. Their impact is projected to be exacerbated by future climate scenarios. HMHs cataloguing is an effective tool to evaluate their associated risks and plan appropriate remediation strategies. However, factors linked to HMHs origin and triggers remain uncertain, which poses a challenge for their cataloguing. Focusing on key HMHs (floods, storm surge, landslides, droughts, and heatwaves), the goal of this review paper is to analyse and present a classification scheme, key features, and elements for designing nature-based solutions (NBS) and mitigating the adverse impacts of HMHs in Europe. For this purpose, we systematically examined the literature on NBS classification and assessed the gaps that hinder the widespread uptake of NBS. Furthermore, we critically evaluated the existing literature to give a better understanding of the HMHs drivers and their interrelationship (causing multi-hazards). Further conceptualisation of classification scheme and categories of NBS shows that relatively few studies have been carried out on utilising the broader concepts of NBS in tackling HMHs and that the classification and effectiveness of each NBS are dependent on the location, architecture, typology, green species, environmental conditions as well as interrelated non-linear systems. NBS are often more cost-effective than hard engineering approaches used within the existing systems, especially when taking into consideration their potential co-benefits. We also evaluated the sources of available data for HMHs and NBS, highlighted gaps in data, and presented strategies to overcome the current shortcomings for the development of the NBS for HMHs. We highlighted specific gaps and barriers that need to be filled since the uptake and upscaling studies of NBS in HMHs reduction is rare. The fundamental concepts and the key technical features of past studies reviewed here could help practitioners to design and implement NBS in a real-world situation.

    B Marti-Cardona, C López-Martínez, J Dolz-Ripollés (2014)Local Isotropy Indicator for SAR Image Filtering: Application to Envisat/ASAR Images of the Doñana Wetland (November 2014), In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing8(4)pp. 1614-1622 IEEE

    This paper explores a geometrical and computationally simple operator, named Ds, for local isotropy assessment on SAR images. It is assumed that isotropic intensity distributions in natural areas, either textured or nontextured, correspond to a single cover class. Ds is used to measure isotropy in processing neighborhoods and decide if they can be considered as belonging to a unique cover class. The speckle statistical properties are used to determine suitable Ds thresholds for discriminating heterogeneous targets from isotropic cover types at different window sizes. An assessment of Ds as an edge detector showed sensitivities similar to those of the ratio edge operator for straight, sharp boundaries, centered in the processing window, but significantly better sensitivity for detecting heterogeneities during the window expansion in multiresolution filtering. Furthermore, Ds presents the advantage versus the ratio edge coefficient of being rotationally invariant, and its computation indicates the direction of the main intensity gradient in the processing window. The Ds operator is used in a multiresolution fashion for filtering ASAR scenes of the Doñana wetland. The intensities in isotropic areas are averaged in order to flatten fluctuations within cover types and facilitate a subsequent land cover classification. The results show high degree of smoothing within textured cover classes, plus effective spatial adaptation to gradients and irregular boundaries, substantiating the usefulness of this operator for filtering SAR data of natural areas with the purpose of classification.