Browsing by Subject "USLE"

Now showing 1 - 3 of 3
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    Comparaison des resultats de l’approche pap/car et le modele usle dans la cartographie et l’estimation qualitative de l’erosion hydrique dans le bassin versant de l’Oued Amlil, (Prerif-Maroc)
    (Universidad de Murcia, Servicio de Publicaciones, 2020) Aiman, Hili; El Khalki, Yahia; Reddad, Hanane; Gartet, Jaouad; Abahrour, Mohamed
    Le présent travail expose les résultats de notre étude concernant la cartographie et l’estimation de l’érosion hydrique selon deux types de méthodes. La première, est celle de PAP/CAR 1998 agisse dans le cadre du Plan d'action pour la Méditerranée (PAM) du PNUE, la seconde est celle du modèle empirique de WISCHMEIER et SMITH 1978 (USLE). Dans le bassin versant de l’Oued Amlil (153.7 km²) situé au Nord-Ouest de Taza (Nord-Est du Maroc), toutes les conditions de déclenchement et d’accélération de l’érosion hydrique sont présentent, des formations lithologiques marneuses tendres et imperméables (71.5%), un couvert végétal très limité (13.2%), et des précipitations agressives et intenses. L'analyse des données naturelles du bassin versant par la méthode de PAP/CAR a permis d’identifier cinq principaux types d’érosion (érosion très élevée 23%, 48% pour l’érosion élevée, la classe d’érosion notable représente 22%, 6% et 1% pour les classes d’érosionfaibles et très faible respectivement. Ensuite, les pertes en sol ont été estimées par la méthode d’USLE, les résultats obtenus permettent l’identification des secteurs à l’échelle du bassin où les pertes connaissent des valeurs élevées 62.3% (risque forte entre 66et 102 t/ha/an (34%), et très fort (26.2%) entre 102 et 355.6 t/ha/an).
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    Erosión y desertificación.-USLE, RUSLE and WEPP models used in mining restored hillslopes
    González Ubierna, S.; Casermeiro Martínez, M.A.; Nicolau Ibarra, J.M.; Universidad de Murcia
    ABSTRACT One of the main problems affecting mining restoration is erosion, which limits the development of functional soils and plant communities. The eroded sediment pollutes and degrades the natural river systems. The objective of this work is to test some of the most used models: USLE (Wischmeier and Smith, 1965, 1978) and RUSLE 1.06 (Toy and Foster, 1998) and WEPP (Nearing et al., 1989), for the case of slopes derived from mining reclamation. The study area is a dump in El Moral coalmine (Utrillas), 60 km. north of Teruel city. We selected three artificial slopes, one with a topsoil substrate and two overburdencovered in order to measure the sediment production during a year. After the comparison between estimated and measured erosion rates two conclusions can be stated: a) RUSLE 1.06 gives the best estimations in most of the cases. However WEPP in its annual option and for the topsoiled slope, works better than RUSLE1.06.
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    Modelización en Geografía Física.-La compresión temporal de los procesos de erosión del suelo. Un análisis regional de la base de datos USLE.
    González-Hidalgo, J.C.; de Luis, M.; López-Bermúdez, F.; Universidad de Murcia
    ABSTRACT When John Thornes and Denis Brunsden wrote in 1977 “How often one hears the researcher (and no less the undergraduate) complain that after weeks of observation “nothing happened” only to learn that, the day after his departure, a flood caused unprecedented erosion and channel changes!” (Thornes and Brunsden, 1977, p. 57), they were focusing to important problems in Geomorphology: the extreme events and time compression of geomorphological processes. Time compression is a fundamental characteristic of geomorphological processes, some times produced by extreme events. Extreme events are rare events, defined by deviation from mean values. But from magnitude-frequency analysis we know that few events, not necessarily extreme, are able to produce a high amount of gemorphological work. Finally time compression of geomorphological processes can be focused by the analysis of largest events defined by ranks, not magnitude. We have analysed the effects of largest events on total soil erosion by using 594 erosion plots from USLE database. Plots are located in different climate regions of USA and have different length of records. The 10-largest daily events mean contribution value is 60% of total soil erosion. There exist a relationship between such percentage and total daily erosive events recorded. The pattern seems to be independent of climate conditions. We discuss the nature of such relationship and the implications in soil erosion research