Soil erosion at three experimental sites in the ­Mediterranean

Abstract

The results of erosion studies carried out at three representative sites in the European Mediterranean basin are discussed. The objectives of the study are to clarify the underlying processes affecting soil erosion and to quantify erosion and runoff in the framework of mitigation of land degradation. The study was carried out at three instrumented field stations using similar layouts and experimental set-ups and harmonized field procedures. Runoff and sediment yield from bounded plots were measured for different types of land use for longer periods.The runoff and sediment values were found to be relatively low, and showed average annual values between 2Á0 and 8Á9 1 m À2 for runoff, and between 20Á2 and 28Á1 g m À2 for sediment yield. The results show that the individual plot response on an event basis shows no relationship between runoff and sediment yield for two of the three sites. On an annual average basis a significant relationship is found between the runoff and sediment yield. Significant differences were observed between different types of land use, especially between semi-natural vegetation, burned and abandoned field cover types on the one hand, and agricultural fields on the other hand. The runoff and erosion values were lowest for the semi-natural fields. It was found that in non-cultivated fields the bounded plots might suffer from depletion of available sediment.It can be concluded that erosion figures are very low for the sites studied, and that the maintenance of semi-natural vegetation may help in the prevention of runoff generation and erosion. It can be concluded that the use of bounded plots may not be as ideal as might be expected from its wide application. In some cases open plots, especially under seminatural land use, may produce much better results, especially when measuring over longer periods.

Runoff and soil loss under individual plants of a semi‐arid Mediterranean shrubland: influence of plant morphology and rainfall intensity

“…Francis and Thornes, 1990;Romero Díaz et al, 1999;Dunjó et al, 2004). All of these studies concluded that typical Mediterranean shrubland vegetation is very efficient in reducing water erosion, even under extreme torrential simulated rainfalls (González-Hidalgo et al, 2004).…”

Causes and underlying processes of measurement variability in field erosion plots in Mediterranean conditions

“…In this sense, it seems that closed erosion plots after several years of functioning show an exhaustion of available material for soil detachment, probably due to the creation of an armour layer at the soil surface and the lack of input of transported material from outside the plot (Morgan, 1986;Ollesch and Vacca, 2002) and low soil formation rate (Dunjó et al, 2004). This depletion of material is expected to be less in bounded cultivated plots (Romero-Díaz et al, 1999) where new soil material is available after tillage.…”

“…There is wide discussion on the influence of the pattern of vegetation and other surface components on runoff and sediment fluxes (Puigdefábregas and Sánchez, 1996;Davenport et al, 1998, Wilcox et al, 2003, including when they are measured in erosion plots (Lavee et al, 1998;Romero Díaz et al, 1999;Calvo-Cases et al, 2005). From the perspective of the replica erosion plots, Fitzjohn et al (2002) found significant differences in the soil moisture pattern between replica plots, despite a similar total vegetation coverage between both plots.…”

The relative efficiency of four representative cropland conversions in reducing water erosion: evidence from long‐term plots in the Loess hilly area, China

“…The temporal changes of runoff and erosion reported in our study are consistent with previous studies that vegetation and land-use changes are important factors in controling yields of runoff and erosion (see also Bryan and Campbell, 1986;Mitchell, 1990;Romero-Díaz et al, 1999). The protective effects of plant cover related to its capability in dissipating the kinetic energy of raindrops (Thornes, 1990), intercepting rainfall and transforming rainfall characteristics as well as affecting the infiltration capacity of the soil (Bellot and Escarré, 1998;Gonzalez-Hidalgo and Bellot, 1997), thus limiting runoff and eventual soil erosion (Woo et al, 1997).…”