Ion Ionita

Effects of land use on annual runoff and soil loss in Europe and the Mediterranean: A meta-analysis of plot data

The largest currently compiled database of plot runoff and soil loss data in Europe and the Mediterranean was analysed to investigate effects of land use on annual soil loss (SL), annual runoff (R) and annual runoff coefficient (RC). This database comprises 227 plot-measuring sites in Europe and the Mediterranean, with SL for 1056 plots (PL) representing 7024 plot-years (PY) and R for 804 PL representing 5327 PY. Despite large data variability, continental-wide trends are observed. Construction sites have the highest mean annual RC (57%) and SL (325 Mg.ha-1.yr-1). Bare soil, vineyards and tree crops have high mean annual RC (5–10%) and SL (10–20 Mg.ha-1.yr-1). Cropland and fallow show similar mean annual RC (8.0 and 7.3%), but lower SL (6.5 and 5.8 Mg.ha-1.yr-1). Plots with (semi-)natural vegetation cover show lowest mean annual RC (<5%) and SL (<1 Mg.ha-1.yr-1). Plot length and slope gradient correlations with R and SL depend on land-use type and are not concurrent for R and SL. Most land-use types show positive correlations between annual R and SL. Plots in cold climates have higher annual RC than plots in temperate and pan-Mediterranean climates. Annual SL in the pan-Mediterranean is less than in temperate zones, due to stony or clayey soils having a low erodibility. Annual RC in the pan-Mediterranean was higher than in temperate zones. Annual R increases strongly with increasing annual precipitation (P) above 500 mm.yr-1, while annual SL was found to stabilize at P > 500 mm.yr-1. For shrubland, annual SL was found to decrease for P > 250–500 mm.yr-1, which is attributed to an accompanying increase in vegetation cover. However, no such trend was found for R. The results allow a rapid assessment of the impact of land-use changes on annual R, RC and SL, based on field-measured plot data.

Gully erosion as a natural and human-induced hazard

The Author(s) 2015. This article is published with open access at Springerlink.com Gully erosion is an important environmental threat throughout the world and affects multiple soil and land functions. There is ample physical evidence of intense gully erosion occurring at various times in the past in different parts of the world. Gullies are one of the few sources of morphological evidence in the landscape of past phases of intense soil erosion, reflecting the impact of environmental change (especially due to interactions between geomorphological features, changes in land use and extreme climatic events). Gully erosion represents a major sediment source, although gully channels often occupy \5 % of the area of a catchment. The development of gullies increases run-off and sediment connectivity in the landscape, hence increasing the risk of flooding and reservoir sedimentation (Verstraeten and Poesen 1999; Poesen et al. 2003). Assessing interactions between environmental change and land degradation is a key issue for environmental scientists, land managers and policy-makers.

Recent Landform Evolution in the Romanian Carpathians and Pericarpathian Regions

In the Romanian Carpathians, developed on crystalline and volcanic rocks, the main geomorphological processes are rockfalls, debris flows, and topples. In the eastern part of the Eastern Carpathians, built up of Cretaceous and Paleogene flysch, landslides and mudflows are of major significance. High and middle mountain karst features and cave systems are also widespread. In the alpine area of the Southern and Eastern Carpathians, avalanches are common on the steep slopes of glacial cirques and valleys. Landslides also develop on high quarry slopes, waste dumps and tailing dams characteristic of the mining sites of the Apuseni Mountains. High discharges along the Carpathian rivers cause intense erosion and the undercutting of slopes, favoring landslides and flooding. Although in fluvial erosion channel incision is predominant (for half of all river sections studied), riverbed aggradation is also observed locally. On the agricultural lands of the Subcarpathians and in the Transylvanian Depression slopes are degraded by sheet and gully erosion, landslides, and mudflows. On the Moldavian Plateau soil erosion, gullying, and landslides are major exogenous geomorphic processes. The country-wide spatial distribution of these geomorphological hazards has been evaluated by several authors (e.g., Geografia României I. 1983; Bălteanu 1997).

Hydraulic efficiency of the discontinuous gullies

Most discontinuous gullies overlying the almost tabular sedimentary strata of the Moldavian Plateau, Eastern Romania exhibit gullying by gully head advance and aggradation of the gully basin floor. According to Heede [Z. Geomorphol. N. F. 18 (1974) 260] the shape factor of the gullies, relating maximum to minimum depth, expresses both channel shape and hydraulic efficiency of channels. Based on a geomorphic approach, this paper shows that a better understanding of gully hydraulic efficiency may be assessed by another shape factor obtained by relating present to filled gully cross-section. A value of 1.0 for this shape factor, Sp/Sf, represents the threshold of hydraulic efficiency. Strong relationships were established between the shape factor and gully length. In addition, an appropriate substitute expressed as the ratio of gully bottom width (Wb) to gully top width (Wt) was found, which is easy to apply and very fast to determine in the field.

The Potential of Permanent Gullies in Europe as Geomorphosites

Geotourism is a useful way to educate societies in the field of geomorphology and related natural hazards. Geosites, including geomorphosites, represent the basis for the development of this type of tourism. This study describes 12 representative gully regions within nine European countries. The characteristics of 42 permanent gullies, gully systems, and badland landscapes are presented. Based on scientific values of the sites, educational lessons to be learned were identified that are mainly related to (i) gullies as a geological window, (ii) present-day geomorphological processes and (iii) stages of historical gully erosion reflecting past human–environment interactions. To evaluate possible education activities, a geotouristic assessment of the studied gullies and badlands was made, based on scientific, educational, functional and touristic indicators. This assessment demonstrates a large difference between the selected gully and badland sites, particularly with regard to functional and tourist values. The geotouristic potential of gullies (badlands) is the highest in Italy and Spain and the lowest in Romania and Latvia. In some countries, permanent gullies are not regarded as geotouristic attractions at all, while in others, they constitute a significant element of their tourism development strategy. In our opinion, all activities must be part of a broader strategy for the development of geotourism in gully and badland regions, for example, gullies may be included as geosites within existing or planned geoparks.