**1. Introduction**

226 Soil Erosion Studies

locally available in a particular area may be considered. Other rainfall intensities may be tested. Consideration of wind and other environmental factors could be included to

The authors recognize the Department of Public Works and Highways (DPWH) of the Republic of the Philippines for the data and facility that they provided for the completion of the study. The authors also recognize the participation of research students and the support of the School of Civil Engineering and Environmental and Sanitary Engineering of the

Bases Conversion Development Authority (BCDA) (2006) *Bases Conversion Development* 

Bureau of Research and Standards (2005) *Use of Coconut Geonets to Protect Riverbanks and* 

Carrascal, H.C., Bergado C.H. I, and Candelaria Ma. D.E. under Dr. Maria Antonia N.

Control" .Department of Civil Engineering, University of the Philippines. Department of Public Works and Highways, Bureau of Research and Standards (2005) *Use of* 

Flood Control and Sabo Engineering Center, Department of Public Works and Highways

Kothyari, U.C. (1996) *Erosion and Sedimentation Problems in India*. Erosion and Sediment

Toy, T.J., Foster, G.R., Renard, K.G. (2002*) Soil Erosion: Processes, Prediction, Measurement, and* 

Morgan, R.P.C. (2005) Soil Erosion and Conservation, 3rd Ed. Blackwell Publishing, USA. Sutherland, R. and Ziegler, A. (2007) *Effectiveness of coir-based rolled erosion control system in reducing sediment transport from Hillslope*. University of Hawaii, Hawaii, USA. Thakur, V.C. (1996) *Landslide Hazard Management and Control in India.* International Centre

Slope Failure Countermeasure, FCSEC DPWH, Philippines

for Integrated Mountain Development. Kathmandu,

*Works of Package 2 SCTEP*. BCDA, Clark Angeles City Pampanga.

*Authority Report on the Result of Vegetation Cover Growth for Clay Slope Protection* 

*Prevent Soil Erosion.* Buda Highway and Malicboy-Macalelon Road Pilot Projects. Bureau of Research and Standards (BRS), Department of Public Works and

Tanchuling. "Slope Suitability of Coco-fiber Geotextile (Cocomat) for Soil Erosion

*Coconut Geonets to Protect River Banks and Prevent Soil Erosion*. DPWH (BRS),

(2002) *Technical Standards and Guidelines for Planning and Design*, Vol. IV: Natural

Yield: Global and Regional Perspectives (Proceedings of the Exeter Symposium,

Mapua Institute of Technology in Intramuros, Manila, Philippines.

simulate stormy weather.

**8. Acknowledgement** 

**9. References** 

Highways (DPWH).

Quezon City, Philippines.

*Control.* John Wiley and Sons.

July 1996).

In that they regulate the water supply, determine air quality, are an essential component of the biodiversity of environments, support biomass production, and are a factor in maintaining and developing populations, soils perform environmental, productive and societal functions which take part in maintaining the fragile balance of territories (EEA, 2008). Therefore, soils constitute a natural heritage which has to be sustainably managed at a local as well as global level. There is now an international consensus on this statement, as human-caused soil degradation has accelerated and taken on more diversified manifestations across the world over the past fifty years.

In Europe, water erosion of soils is seen as one of the main forms of degradation of arable land. The surface of European soil affected by erosion is estimated to be around 12%. From continental to local levels, territorial agencies need to avail of geo-referenced information to Fig.ht against or prevent soil erosion. The aim in particular is to map the areas most affected or likely to be affected, in order to formulate restorative or preventative measures (*Gobin* et al., 2004). Besides, in the current context dominated by a global warming which will in the mid and long term disrupt the natural components of habitats, it seems necessary to provide the representatives of civil society with new elements which facilitate rationalized anticipation of future evolutions and of consequences in terms of land management.

To that end, erosion risk maps are essential documents. They are the result in particular of the production of semi-quantitative erosion models such as PSIAC (PSIAC, 1968; Hadley et al., 1985), FSM (Verstraeten et al., 2003; de Vente et al., 2005), EHU (Stocking and Elwell, 1973), CORINE (EEA, 1992) or even INRA (Le Bissonnais and Daroussin, 2001) and PESERA (Kirkby et al., 2003).

Whereas all the semi-quantitative models can be characterized by their simplicity and their high application potential to global spatial and temporal scales, their degree of accuracy does not allow the mapping of erosion problems at local level. To overcome this difficulty, we have developed the SCALES model (Le Gouée et al., 2010). SCALES is a model which offers similarities with semi-quantitative models as regards structure of model, holistic positioning, and strong reproducibility potential, but also with physical and empirical models because of the great accuracy of the data used and of their spatial representation.

SCALES: An Original Model to Diagnose Soil Erosion Hazard

diagnostic to intervention scales of local land managers.

will lead to the estimation of level of hazard.

years in the Department of Calvados (Le Gouée et al., 2008).

influenced by the ocean, the main mechanism acting on the soil crusting.

**2.2.2 Parameters and input data** 

topography. The computational model is therefore a global indicator.

period. Therefore, the erosion hazard has to be considered as a mean hazard.

**2.2 The SCALES model characteristics** 

of England.

**2.2.1 Basic statements** 

and Assess the Impact of Climate Change on Its Evolution 229

The SCALES approach can be reproduced where such agricultural practices as descrubed above occur and where the climate is a mild maritime one. In Europe, the application of the model can be carried out all along the Oceanic façade from the N-W of Spain until the South

SCALES is displayed as a regional scale applicable model keeping high precision and high quality of information at local scale. This tool allows us to produce in a short time a diagnostic of erosion hazard using high resolution data coming from accurate data. This diagnostic is specific to arable lands. It cannot be proposed in context of "natural" vegetation such as woods or forests or for urbanized areas. SCALES is also designed to be accessible to a wide range of companies dealing with questions of environmental relevance. Furthermore, this model also displays the possibility to aggregate hazard data with administrative or hydrological units like municipality and elementary catchment, in order to adapt the

SCALES is a tree form model based on the use of GIS in order to map the potential sensibility of areas and soil erosion hazard. Potential sensibility of areas represents the first fundamental concept of the model. This concept aims to precise if the studied area is able to generate erosive runoff when we integrate both erodibility of soils, land-use and

Erosion hazard defines the probability of appearance of soil erosion by water when potential sensibility and rainfall erosivity are put together. The rainfall erosivity depends on meteoric conditions. The latter will be higher during wet years and lower during dry years. We thus estimate a mean of rainfall erosivity based on rainfall data originating from pluri-annual

The factors of evaluation of soil erosion hazard (soil erosion, agricultural practices, topography and rainfall erosivity) are displayed by the input data which can be of quantitative or qualitative relevance. Each factor is defined by one or several types of input data. All data types are converted in measurable data which in turn will express levels of pressure on the erosive runoff trigger. Some input data are combined in order to obtain combined data which generate also level pressure. Levels of pressure from combined data

The choice of input data (Fig. 2) in the view of characterizing factors of evaluation of erosion hazard result from well-established scientific concepts in the literature, expert opinions and by conclusions originating from numerous personal observations for two

In order to estimate the soil erodibility, we selected and considered the structual instability as input data. This characteristic corresponds to the soils sensibility to degradation of its superficial structure by rainfalls. The degradation by water can be explained by the different physical and physico-chemical mechanisms among which we can cite: bursting, mechanical disaggregation, disaggregation by differential blow, and the chemical spread. Mechanical disaggregation due to the impact of rain drops constitute, in the temperate regions

After having shown the operational capability of SCALES at the scale of the Calvados department (Le Gouée et al., 2008) which represents 5,500 km² (Fig. 1), we then focused our efforts on adapting this model to produce a diagnosis of the erosion hazard at seasonal and monthly scales (Stepkow, 2008). That approach enabled us most recently to offer a prospective insight into the effects of climate change in the distant future (scenario A1B of the IPCC for 2100) on the evolution of soil erosion hazard in Normandy (Goulet, 2010).

Fig. 1. The regional council of Basse-Normandie. A: Catchment of the Branche. B: Catchment of the Lingèvres.
