Youssouf Koussoube

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.

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.

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.

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.

Use of High Resolution Satellite Images for the Calibration of Hydro-geological Models in Semi-Arid Regions: A Case Study

In this paper we present the preliminary results of a project devoted to use hydrologic and remote sensing models and data for water resource management in semi-arid regions. The project is developed in the Sahel region of Burkina Faso, where a set of high resolution synthetic aperture radar (SAR) images was acquired. The rationale of the project along with the preliminary results obtained by the processing of high resolution Cosmo-SkyMed data are presented and discussed.

Hydrological modeling in ungauged basins using SAR data

In this paper we propose a methodology devoted to exploit high resolution radars for monitoring water bodies in semi-arid countries. The proposed approach is based on appropriate registration, calibration and processing of SAR data, producing information ready to use by end-users. The obtained results were used to (i) estimate a relationship between surface and volume of water stored in reservoirs and (ii) validate a hydrological model that simulates the time evolution of water availability.

Monitoring Soil Erosion and Reservoir Sedimentation in Semi-arid Region Through Remote Sensed SAR Data: A Case Study in Yatenga Region, Burkina Faso

Monitoring soil erosion and consequent reservoirs sedimentation is necessary for a proper planning of water and soil conservation measures. Applicability to large scale and cheapness of the monitoring system is crucial for low income countries. The present work proposes a novel approach in which remote sensed SAR and Landsat data are used for monitoring reservoir’s sedimentation and for mapping the soil erosion risk at catchment scale. Novel techniques for SAR imagery pre-processing are combined with empirical soil loss estimates. A SAR derived DEM is used to monitor the soil sedimentation rate of small reservoirs. The USLE (Universal Soil Loss Equation) method is used to draw a soil erosion risk map and to roughly estimate the total soil loss at catchment scale.

Synthetic Aperture Radars for humanitarian purposes: Products and opportunities

In this paper we present the available products and the future opportunities derived by the use of Synthetic Aperture Radar data for humanitarian projects. A set of images relevant to an area of the Sahel, in Burkina Faso have been used for supporting the proposed claims. Along with the technical problems related with the image interpretation, we focus on the economic accessibility of the data, that mainly limited the use of SAR images in low income countries. The future availability of free access data makes their use very attractive, provided that appropriate knowledge is available for interpreting the images.