Maria Nicolina Papa

Effectiveness of high-resolution SAR for water resource management in low-income semi-arid countries

This article presents an efficient framework and a sustainable pilot project on the effective use of spaceborne synthetic aperture radar (SAR) in low-income countries and semi-arid climatic contexts. The technical efficiency was pursued by integrating SAR models and hydrological assessment methods; the socio-economical sustainability was guaranteed by the joint work of scientists, technicians, and volunteers. The pilot project was developed in the Yatenga region, a Sahelian area in northern Burkina Faso. In particular, an original development of SAR interferometry algorithms was tailored to the peculiar climate, the soil characteristics, and the land cover of the semi-arid regions. A digital elevation model (DEM) was derived, and an original approach based on the use of SAR amplitude images is proposed for its validation. The achieved resolution (9 m) is significantly better than that of the previously available DEMs in the study area (30 m). Based on the DEM, the soil sedimentation rate of small reservoirs was estimated together with the average soil loss in the contributing catchments due to the erosion process. A multi-temporal filter was implemented on the SAR images for monitoring of water intake volume in small reservoirs, and its seasonal evolution. The developed tools provide an innovative contribution for the improvement of water resource management in the study area. This approach is repeatable and scalable to suit situations with similar economic and climatic conditions.

Sentinel-1 for Monitoring Reservoirs: A Performance Analysis

In this paper we explore the performances and the opportunities provided by the European satellite Sentinel-1 for water resource management applications in low-income countries. The analysis is supported by a synthetic aperture radar (SAR) simulator, which allowed the quantification of the expected characteristics of Sentinel-1 products in three applications: interferometric digital elevation models (DEMs) generation, land cover mapping and estimation of water volumes retained by small reservoirs. The obtained results quantitatively show that Sentinel-1 data characteristics are fully suitable for most of the application already explored in the recent SAR literature.

Landslide risk perception: a case study in Southern Italy

Perceptions of risk are a key issue when seeking to develop systems, practices and policies to protect local populations. This is particularly evident when risk mitigation strategies involve non-structural measures such as relocation and warning systems which presuppose the active involvement of the communities in question. This study adopts an interdisciplinary approach to studying the perceptions, knowledge and opinions on landslide risk amongst residents in Sarno, a small town in Southern Italy which was hit by disastrous landslides on 5–6 May 1998. The paper presents the results of a survey conducted in the months of March, April and May 2013 using a purpose-designed questionnaire. The survey was conducted using face-to-face interviews with 100 residents, 60 of whom live inside the so-called “red zone”, a territory declared at high residual risk soon after the events of 1998. The questionnaire included questions relating to perceived risk exposure, trust in institutions responsible for risk management, evaluations of risk mitigation measures and the early-warning strategy. The results of the study clearly emerges, amongst other issues, that the organisms which are responsible for risk management in Sarno need to develop more effective communication strategies in order to transmit knowledge about the actions implemented to reduce landslide risk in the area.

Modeling Watershed Response in Semiarid Regions With High-Resolution Synthetic Aperture Radars

In this paper, we propose a methodology devoted to exploit the outstanding characteristics of COSMO-SkyMed for monitoring water bodies in semiarid countries at a scale never experienced before. The proposed approach, based on appropriate registration, calibration, and processing of synthetic aperture radar (SAR) data, allows outperforming the previously available methods for monitoring small reservoirs, mainly carried out with optical data, and severely limited by the presence of cloud coverage, which is a frequent condition in wet season. A tool has been developed for computing the water volumes retained in small reservoirs based on SAR-derived digital elevation model. These data have been used to derive a relationship between storage volumes and surface areas that can be used when bathymetric information is unavailable. Due to the lack of direct measures of rivers discharge, the time evolution of water volumes retained at reservoirs has been used to validate a simple rainfall-runoff hydrological model that can provide useful recommendation for the management of small reservoirs. Operational scenarios concerning the improvement in the efficiency of reservoirs management and the estimation of their impact on downstream area point out the applicative outcomes of the proposed method.

High resolution SAR for monitoring of reservoirs sedimentation and soil erosion in semi arid regions

High resolution SAR data can be a powerful support mainly in areas where the acquisition of in situ information is hampered by physical or economic obstacles. Purpose of this paper is to present an approach to exploit high resolution SAR data for monitoring the temporal evolution of reservoir characteristics in semi-arid regions. Classical and innovative techniques are tailored on the specific climatic conditions of these regions, characterized by the alternation of a three months wet and a nine months dry seasons. Results from a case study developed in Burkina Faso show that the combined use of amplitude and phase information allows the estimation of the eroded areas and a meaningful monitoring of the reservoirs sedimentation.

Effects of climate change on shallow landslides in a small coastal catchment in southern Italy

In different areas of the world, shallow landslides represent a remarkable hazard inducing fatalities and economic damages. Then, the evaluation about potential variation in frequency of such hazard under the effect of climate changes should be a priority for defining reliable adaptation measurements. Unfortunately, current performances of climate models on sub-daily scales, relevant for heavy rainfall events triggering shallow landslides, are not reliable enough to be used directly for performing slope stability analysis. In an attempt to overcome the constrains by gap in time resolution between climate and hazard models, the paper presents an integrated suitable approach for estimating future variations in shallow landslide hazard and managing the uncertainties associated with climate and sub-daily downscaling models. The approach is tested on a small basin on Amalfi coast (southern Italy). Basing on available basin scale critical rainfall thresholds, the paper outlines how the projected changes in precipitation patterns could affect local slope stability magnitude scenarios with different relevances as effect of investigated time horizon and concentration scenario. The paper concludes with qualitative evaluations on the future effectiveness of the local operative warning system in a climate change framework.

COSMO-SkyMed AO projects - Use of high resolution SAR data for water resource management in semi arid regions

In this paper we present the results of a project approved in the frame of the 2007 Cosmo-Skymed AO, devoted to use high resolution data for hydrology applications in semi-arid context. A case study was developed in Burkina Faso, a West Africa country, characterized by the alternation of intense rainy and dry seasons. In this paper we present the rationale of the project along with two of the obtained products concerning the estimation of eroded areas and the surface water recharge.

Experimental Investigation on the Effects of the Fixed Boundaries in Channelized Dry Granular Flows

The dynamics of granular mixtures, involved in several geophysical phenomena like rock avalanches and debris flows, is far from being completely understood. Several features of their motion, such as non-local and boundary effects, still represent open problems. An extensive experimental study on free-surface channelized granular flows is here presented, where the effects of the fixed boundaries are systematically investigated. The entire experimental data set is obtained by using a homogenous acetal-polymeric granular material and three different basal surfaces, allowing different kinematic boundary conditions. Velocity profiles at both the sidewall and the free surface are obtained by using high-speed cameras and the open-source particle image velocimetry code, PIVlab. Significantly, different sidewall velocity profiles are observed by varying the basal roughness and the flow depth. Owing to sidewall friction and non-local effects, such profiles exhibit a clear rheological stratification for high enough flow depths and they can be well described by recurring to composite functions, variously formed of linear, Bagnold and exponential scalings. Moreover, it has been discovered that transitions from one velocity profile to another are also possible on the same basal surface by merely varying the flow depth. This shape transition is due partly to the sidewall resistances, the basal boundary condition and, in particular, the occurrence/inhibition of basal grain rolling. In most of the experiments, the normal-to-bed velocity profiles and the velocity measurements at the free surface strongly suggest the occurrence of a secondary circulating flow, made possible by a chiefly collisional regime beneath the free surface.

Innovative Synthetic Aperture Radar Products for the Management of Land and Water

The use of satellite data for land management optimization is extremely powerful in low-income countries, where in situ measurements require costly and time-consuming solutions. In this paper we present the innovative results of a pilot-project that used high resolution synthetic aperture radar (SAR) data for agriculture physical parameter retrieving. In particular, we present land use maps and a vegetation index evaluated at small scale, thank to the use of Cosmo-Skymed data.

Use of high-resolution SAR data for the monitoring of water resources in Burkina Faso

The integrated management of water resources is a crucial problem for improving the quality of life in Sub-Saharian Africa. Several satellites everyday acquire a huge amount of physical information that could be employed as a support for solving agriculture and water problems. In this paper we present a project devoted to exploit the use of high resolution synthetic aperture radar (SAR) images for water resource management at no cost for the users. A case study is developed in the Yatenga region, in the northern Burkina Faso, integrating hydrologic and remote sensing models in order to improve the capacity of predicting flood and drought events. Main attention is posed here on the innovative fractal techniques developed for the extraction of geometrical and physical parameters that can be used for calibrating hydro-geological models.