Soil Conservation and Sediment Control in Europe

Anton Charles Imeson

（Foundation 3D Environmental Change，Curtiuslaan 14，1851 AM Heiloo，The Netherlands，http：／／www.3d－ec.com）

Soil Conservation and Sediment Control in Europe

Anton Charles Imeson

（Foundation 3D Environmental Change，Curtiuslaan 14，1851 AM Heiloo，The Netherlands，http：／／www.3d－ec.com）

The objective of this paper is to provide an overview of soil conservation and sediment control in Europe from the perspectives of policymakers seeking solutions to current problems of soil loss and flooding.Data and information are derived from detailed reports written in support of the European Soils Directive，that addressed the threats facing European soils and from workshops organised to identify best practices and achieve sustainable land use in different EU countries.These were organised by the SCAPE（Strategies for Soil Conservation and Protection in Europe）supporting action.Regarding technicalmeasures used to limit erosion and restore ecosystems，there ismuch similarity between Europe and China.Themain soil and land degradation problems that soil conservation practitioners and scientists have to address are caused by land use andmanagement impacts thathave proved difficultor impossible to resistbecause of political conditions.The political leadership that regarded soil conservation and sediment control，as a cornerstone of sustainable economic development，which seemed to be present eight years，is urgently required oncemore.

soil conservation；sustainable land management；European soil policy

1 Soil Erosion and Conservation in Europe

A recent overview of historical soil erosion and conservation in Europe is given by Lang and Bork（2006）.The consensus，is that areasmost affected by erosion，are in the Northern Loess Belt and in the Mediterranean region，and thatmountain and northern regions，with short growing seasons and frost，are also vulnerable to erosion.The EU has recently published maps of the different threats facing European soils，including the risk to erosion.These and many other documents can be downloaded from the European Soil Bureau home page.

In Western Europe（e.g.England and W.France），erosion is a problem during the winter monthswhen soil profiles are saturated with water and this may be caused by low intensity rainfall.Going eastwards，with amore continental climate，high intensity summer rainfall storms become more important for erosion，and in Central Europe，as in China，this is whenmost problems occur.However，rainfall increases with altitude（orographic rainfall），and in the mountains of many countries in Central and Southern Europe（as in Austria，Italy and France）summer rainfall may be heavy.There are frequently erosive summer thunderstorms that occasionally produce comparable summer rainfall conditions to those in China with verymuch flood damage in the river valleys.Particularly along some parts of the Mediterranean coast in the Autumn torrential downpours occur once every few years，causing the loss of life and flood damage.The annual variability though is very high.Land use and management practices in central Europe have had to adapt to high rates of erosion risk every four or five years.

In northern Europe，most erosion occurs during the spring period of snowmelt.Amajor factor is also autumn ploughingwhich leaves the soil bare throughout thewinter and spring.In areas where the soil freezes in the winter before it is covered with snow，there tend to be erosion problems in the spring.In south-eastern Europe，the Carpathian mountains and Danube basin have more continental climate conditions，like China but and there ismuch erosion in themountains of Romania as aresult of forest clearance.However，towards the southeast in the agricultural areas summer droughts become more of a problem and steppe like soils are found.The dryer areas of SE Europe have short growing seasons because of lack ofmoisture in the summer and cold winters whichmeans that the soils can become fragile.

Limestone and karst areas are very common in many parts of Europe but especially in the Northern Mediterranean region and on the large Mediterranean Islands.Crete，Slovenia，Dalmatia，Greece and Italy，as a result of intensive grazing，may contain rocky desert-like areas that resemble those in China.In Crete，most rainfall occurs in winter but in some specific areas of the northern Mediterranean rainfall is more evenly distributed throughout the year，or it has amaximum in the summer.In Spain，there are extensive areas of limestone in SE and Central Spain which are quite humid and which are in many ways compared with China.Many limestone and marl areas that were once heavily grazed are now abandoned for agriculture and have naturally regenerated or planted forests.Limestone areas are very important for groundwater recharge so that care has to be taken tomake to ensure that the consequences of afforestation for irrigation are understood and managed.

2 Historical Erosion in Econom ically M arginal Areas

Europe has experienced soil erosion problems for thousands of years.Historians have documented former sedimentation problems and soil conservation often in the past.In the past soil degradation is considered to be characteristic of economically marginal areas and of areas where there is a large annual variability in rainfall.However，when forests were cut down to provide charcoal for themanufacture of iron or copper，or as a source of timber for fuel or ships，this was often followed by erosion and sedimentation.

At the end of the last century，many areas of Europe that were agriculturally marginal suffered from land degradation and erosion and there was a subsistence economy and much poverty at times.In the Mediterranean area the population in the rural areas was usually very high.Land use practices and conditions resembled those found in parts ofMorocco today.Erosion was often caused by policies that aimed to achieve national self-sufficiency in wheat or rice production.On the other-hand there were very many afforestation projects in degradedmountain areas that transformed landscapes.A major feature of the Mediterranean region is the littoralisation of the population that moved to the major cities and coast.This was for social reasons（Medalus 2003）not just because land degradation had made agriculture unproductive.Of special interest for China is that in some areas of Europe（notably France，Spain，Portugal，Belgium，The Netherlands，Germany and Italy）there are records showing the long term positive impact of afforestation and other soil conservation on the sediment load and erosion of rivers.There are several studies of sediment budgets in catchments of different sizes that commenced during the International Hydrological Decade of 1960－1970.

Asmentioned，limestone areaswith rocky desertification are very extensive，particularly Spain，Greece，France and Slovenia.Many limestone areas that were formerly barren and occupied by very many farmers are now forested.These provide an example of how voluntary depopulation can lead to the recovery of ecosystem functions.In the case of the Mediterranean region，forest fire is a risk，but this would probably not be the case in China where climate conditions are less conducive to fire.

3 W hat is the Best Practice？

Learning from‘best practices’is a simple but effective way of identifying and promoting positive changes in soil conservation approaches.It facilitates stakeholder participation and increases the relevance of scientific studies.Best practiceswith respect to themethods of data measurement and analysis are frequently being discussed at scientific conferences and in the European soil conservation literature.The following table gives an example of the different types of Best Practice and measurement practice.

4 Governance

As there is no Governmental organisation of soil conservation at the European level，most government discussion of best practices is at the Nation level.Onthe other hand independent citizens have created European societies（such as the European Society of Soil Conservation）and the EU Directorate for Scientific Research and the European Joint Research Centre have organised scientific，aswell as the European Geophysics Union are organising data and knowledge at the European level which could support European level policy.

At the European level there are various directives（for examplewith respect towater，nitrates and sewage sludge and wildlife）.Thismeans that all of the different countries and regions have their own different policies，priorities legislation and Acts thatmight provide some kind of a framework for soil conservation activities.

Table1 Examples of Best Practices at different levels in Europe

Nevertheless，there is great similarity between the countries because of the use of the same soil conservation training books，the exchange and diffusion of scientific and practical information and the European U-nion framework programmes.

Most of the European Countries are party to the U-nited Nations Convention to Combat Desertification.Just like China，they have National Action Plans to Combat Desertification and these have identified priorities such as ecosystem restoration and afforestation.

The European Union and governments such as Spain and Italy have supported much research in both monitoring land degradation and erosion.An environment has been created in which European scientists work together in Europe.These include the COST ac-tions and Framework programs.European scientists.Often scientific research is focused on relatively narrow objectives and there is seldom a management of the outcomes or funding of follow up.The focus is on the training of scientists and human capital.There is a good general scientific knowledge about best practices.

5 Conclusion：some challenges

In general soil conservation and protection is the responsibility of the Ministry of the Environment and Spatial Planning.A major problem in Europe is that responsibilities for land and soil aremanaged by different sectors so that there is usually little provision for cross cutting problems that affect society in the long term.Every best practice handbook in soil conservation stresses the need to have an integrated approach that brings together soil，water and land usemanagement in one responsible authority.This is the case in countries like New Zealand and South Africa which have excellent approaches.Before about 1980 the approach of most European countries was to manage the hydrology of the catchment source area.This is still the case in many East European countries.Recently in some countries such as England floods are the responsibility of civil engineers and the link with land use is notmade.One country that often has excellent best practices is France.French engineersmanage the flows of sediment in rivers in a way that takes account of the interactions between hillslope and river channel dynamics over periods of at least150 years In Spain the Government and regions havemany institutions in place that are responsible for managing sediment and erosion.These include the Government Research Council Organisations and the Hydrological Services.

A useful impression of soil erosion issues and examples of best practices in Europe can be found in the recently published book by Boardman et al.The first 450 pages of the book reviews soil erosion in each of34 countries and then another 400 pages describe processes.The final conclusions focus on reducing erosion risk.Also the TechnicalWorking Group Reports of the soil strategy provide an extensive resource available at the European Soil Bureau site shown in the literature list below.

Acknow ledgement

The information upon which this paper is based was supported by verymany people who contributed to discussions that took place during research projects and meetings supported by the EU DG Research.In particular I would like to thank Denis Peter，Maria Yeroyanni，Oli Arnalds and Luca Montanarella for their insights into soil research and soil policy and Contract EVKT－CT2002－20016.

For this specific paper I gratefully thank the EU China projectand Alterra for the opportunity to collaborate with them in the EU Chinawatershed rehabilitation project.Igratefully acknowledge the contributions and help of Piet van de Poel，Lars Skov Andersen and Zhou Rui for their advice and suggestions for improvementsmade to a study on which this paper is based.The idea of comparing soil conservation and protection in China and Europe is an excellent initiative of the project and one that will lead to a deepening insight and awareness regarding how better soil conservation and sustainable land use can be achieved in the world and this is.

［1］ DORREN L K A，IMESON A C.Soil erosion and the adaptive cyclemetaphor［J］.Land Degradation and Development，2005，（16）：509－516.

［2］ DESCROIX L，GAUTIER E.Water erosion in the southern French Alps：Climatic and Human Mechanisms［J］.Catena，2002，50（1）：53－85.

［3］ DG Environment Report of the soil technical working group on erosion［EB／OL］.http：／／eusoils.jrc.it／ESDB_ Archive／Policies／STSWeb／vol2.pdf.

［4］ DORREN L，BERGER F，IMESON A C，et al.Integrity，stability and management of protection forests in the European Alps［J］.Forest Ecology and Management，2004，195（1－2）：165－176.

［5］ SCHMITT A，DOTTERWEICH M，SCHMIDTCHEN G，et al.Vineyards，hopgardens and recent afforestation：effects of late Holocene land use change on soil erosion in northern Bavaria，Germany［J］.Catena，2003，51（3－4）：241－254.

［6］ THORNES J B，BURKE S.Actions taken by national governmental organisations to mitigate desertification in the Mediterranean［R］.London：Concerted Action on Mediterranean Desertification Kings College，University of London，2006.

（Edited by LIU Yun-fei，YIXin-hua）

S157 Document code：A

1001－5485（2010）09－0083－04

此文由“2009水资源与可持续发展高层论坛”供稿。