ETUDE DE LA CAPACITE AEROBIE CHEZ LES ATHLETES ALGERIENS DE FOND ET DE DEMI-FOND

Résumé En dépit des nombreux titres et records réalisés avec brio durant les premières années de la décennie 90 par Noureddine MORCELI et Hassiba BOULMERKA, force est de reconnaître que le demi-fond et le fond algériens demeurent loin du niveau mondial. Pourtant, les bons résultats obtenus dans les catégories de jeunes, même au niveau international, auraient pu augurer d’une relève certaine, si leurs auteurs n’étaient passés dans l’anonymat une fois la catégorie senior atteinte. Nous avons essayé d’expliquer, dans notre présente étude, les raisons de ce marasme en nous basant sur la réalité du terrain. Pour ce faire, nous nous sommes rapprochés des athlètes Algériens pratiquant le demi-fond et le fond de niveau national pour nous imprégner du contenu de leur entraînement durant trois (03) saisons consécutives (1995, 1996 et 1997). Dans le même temps, nous avons mis en place une batterie de tests consistant à apprécier sur le terrain, par le biais de tests indirects, les paramètres physiologiques et physiques les plus déterminants dans la spécialité. Il s’agit notamment de la consommation maximale d’oxygène (Vo2max), la vitesse maximale aérobie (V.M.A), le seuil anaérobie (S.An) et la capacité anaérobie (C.An). Les investigations ont été menées auprès d’une population de coureurs de demi-fond et de fond tous volontaires. L’analyse du contenu d’entraînement fait ressortir l’absence de rationalité au niveau méthodologique notamment en ce qui concerne la charge d’entraînement (répartition et maîtrise de ses différentes composantes...) L’étude longitudinale sur trois années montre une stagnation, aussi bien des résultats de différents tests effectués sur le terrain que des performances individuelles et moyennes. &nbsp

Proceedings of the international seminar rain water harvesting and management of small reservoirs in arid and semiarid areas

Within the HYDROMED program, to assess hydrological variables describing the water balance of small dams, each reservoir is equipped with a water level gauge, an evaporation pan, and two stations for automatic data collection. The first station is connected to a tipping bucket rain gauge (resolution of 0.5 mm rainfall), while the second is connected to a submerged probe that measures the water level, within 1 cm, and temperature each 5 minutes. The spillway is designed in such a way that the discharge can be estimated. The bathymetry of each reservoir is recorded at least once every hydrological year, and is compared with a detailed ground survey, making it possible to determine the silting rate of each reservoir, and to create level-volume and level-surface relationships. The water abstraction for main users around the reservoirs is observed daily. A software package allows to take the data directly and store it in a single hydrological data bank : rainfall and evaporation, level-volume and level surface curves for the reservoir, water level-spillway discharge curves, water level, spillway discharge, volume and surface area of water in the reservoir, water abstraction. The software allows editing tables of data and curves. Many different time steps can be choosen and various ways to present the datda are possible. For a certain period t, the general water balance equation for a reservoir can be applied by using the principle of water volume conservation. The variation of the water volume stored in the reservoir is equal to the sum of water volumes entering minus water volumes exiting the system... (D'après résumé d'auteur

Exceptional rainfall characteristics related to erosion risk in semiarid Tunisia

The Tunisian Dorsal area is representative of the semiarid Mediterranean region in terms of water resources availability as well as exceptional rainfall characteristics, runoff generation, and soil loss risk. In this context, soil properties, surface management practices together with highly intensive rainfall make the soils vulnerable to erosion. If the exceptional rainfall characteristics are linked to different erosion types, the erosion risk could be evaluated in a simple and straightforward way. In this regard, a short time-scale rainfall data base from the Dorsal area was analysed in the paper. The procedure used involves finding a representative duration between 1-60 min for the exceptional rainfall characteristics. Rainfall intensities of different return periods are then related to the different erosion types. The identified exceptional rainfall durations between 1-60 min were analyzed in terms of number of events, depth, average intensity and maximum intensity. Results show that the 15-min duration maximum intensity can be used to evaluate erosion risk based on soil erosion type. The developed methodology can be used to evaluate erosion risk in semiarid regions based on exceptional rainfall characteristics. In practical terms the results can be used to better manage catchments that are vulnerable to soil erosion

Hill lakes : innovative approach for sustainable rural management in the semi-arid areas in Tunisia

In Tunisian semi-arid regions, where water is a rare commodity and the large dams cannot be justified considering the very limited water contributions and the very high evapotranspiration, innovative techniques of harvesting water have been adopted. Tunisia has initiated a policy of small dam construction aiming to combine land and water management with socioeconomic development. They also target erosion control and protection of downstream infrastructure. Integrated rural development is achieved through the provision of a scarce but vital renewable resource. Using the results of multi-disciplinary research carried out in a network of 25 hill lakes implemented in a semi-arid area, the present article shows the role of small dams in the mobilization and management of water and soil resources. The issues involved in integrated development around hill reservoirs are closely linked to the sustainability of water. The agricultural development must be adapted to the life expectancy of the dam and the availability of water in dry periods. The recharge of the groundwater in the aquifers improves the potential for development. However, the impact of the stored water on health must be studied. The environmental impact of the lake structures is linked to the quality of the water and the maintenance of its supply