Micromorphological description of vernacular cob process and comparison with rammed earth

International audiencePast builders have developed very low-embodied energy construction techniques optimizing the use of local building materials. These techniques are a source of inspiration for modern sustainable building. Unfortunately, this know-how was orally transmitted andwas lost as earth construction fell into disuse during the 20th century in European countries.The absence of written documents makes necessary to use an archaeological approach in orderto rediscover these construction strategies. Micromorphological analysis of thin sections collected in earth building walls was used for the first time to describe cob construction tech-nique and highlighted several typical pedofeatures allowing to clearly identifying this process.Finally, a first comparison of the cob and rammed earth micromorphological features permitted to identify two key factors to distinguish these two techniques, the manufacturing state (solid or plastic) and the organization of the material in the wall

A new methodology to identify and quantify material resource at a large scale for earth construction – Application to cob in Brittany

A new methodology based on the cross-referencing of spatialized pedological and heritage data is proposed to identify and quantify soil resources available for earth construction. The paper underlines the pedological particularities of areas containing earth heritage and uses these particularities to propose criteria to assess the suitability of soils for modern earth construction. The methodology applied at the regional scale in France (for a given area of 27,200 km2 in Brittany) enabled to specify five new texture classes (balance between clay, silt, sand and gravel content) of suitability for cob soils. This result calls into question recommendations available in the literature. The methodology also provides data on the scale of availability of the resource to repair earth built heritage (cob) or to build new low impact buildings with integrated modern cob walls. In the studied area the potential waste recovery of 2.8 Mt per year is measured, highlighting the large availability of materials for earth construction. At least 23% of earthwork wastes of Brittany are suitable for earth construction (0.7 Mt). However, earth remains a non-renewable material and this resource has to be properly managed, requiring an appropriate building design and maintenance in order to increase longevity and to avoid the use of admixture, preventing earth reversibility at end of life

Comparing three approaches of spatial disaggregation of legacy soil maps based on 1 DSMART algorithm

Enhancing the spatial resolution of pedological information is a great challenge in the field of Digital Soil 34 Mapping (DSM). Several techniques have emerged to disaggregate conventional soil maps initially 35 available at coarser spatial resolution than required for solving environmental and agricultural issues. At the 36 regional level, polygon maps represent soil cover as a tessellation of polygons defining Soil Map Units 37 (SMU), where each SMU can include one or several Soil Type Units (STU) with given proportions derived 38 from expert knowledge. Such polygon maps can be disaggregated at finer spatial resolution by machine 39 learning algorithms using the Disaggregation and Harmonisation of Soil Map Units Through Resampled 40 Classification Trees (DSMART) algorithm. This study aimed to compare three approaches of spatial 41 disaggregation of legacy soil maps based on DSMART decision trees to test the hypothesis that the 42 disaggregation of soil landscape distribution rules may improve the accuracy of the resulting soil maps. 43 Overall, two modified DSMART algorithm (DSMART with extra soil profiles, DSMART with soil 44 landscape relationships) and the original DSMART algorithm were tested. The quality of disaggregated soil 45 maps at 50 m resolution was assessed over a large study area (6,775 km2) using an external validation based 46 on independent 135 soil profiles selected by probability sampling, 755 legacy soil profiles and existing 47 detailed 1:25,000 soil maps. Pairwise comparisons were also performed, using Shannon entropy measure, 48 to spatially locate differences between disaggregated maps. The main results show that adding soil landscape 49 relationships in the disaggregation process enhances the performance of prediction of soil type distribution. 50 Considering the three most probable STU and using 135 independent soil profiles, the overall accuracy 51 measures are: 19.8 % for DSMART with expert rules against 18.1 % for the original DSMART and 16.9 % 52 for DSMART with extra soil profiles. These measures were almost twofold higher when validated using 53 3x3 windows. They achieved 28.5% for DSMART with soil landscape relationships, 25.3% and 21% for 54 original DSMART and DSMART with extra soil observations, respectively. In general, adding soil 55 landscape relationships as well as extra soil observations constraints the model to predict a specific STU 56 that can occur in specific environmental conditions. Thus, including global soil landscape expert rules in 57 the DSMART algorithm is crucial to obtain consistent soil maps with clear internal disaggregation of SMU 58 across the landscape

Pemodelan Lahan Basah Potensial Berdasarkan Indeks Topografi di Bretagne, Prancis

Wetlands represent an important natural resource which supports natural biodiversity. In France, in mentioned wetlands, it called potential wetlands, which have potential in its use.Topography and geomorphology play a major role for the development of wetlands and are decisive factors for modeling wetlands extension.The importance of identifying wetlands, can be used as a basis for determining the development priorities that will be based on technical and socioeconomic aspects The objective of this research was to predict the spatial extent of potential wetlands in Brittany, France from a topographic index calibrated on a set of 10 detailed soil maps. In identifying potential wetlands, it based on soil hydromorphwhich conducted by method 4 criteria. The following four stages of analysis were respectively categorized: (a) identification hidromorphy, (b) calculation topographic index, (c) calculation of threshold, (d) validation.A threshold method was conducted between soil maps and topographic index to indicate the similarity condition. We use for threshold and validation a new way using 120 combination of soil maps. The result oftopographic index was 4.7 and it was applied for all Brittany

Pemodelan Lahan Basah Potensial Berdasarkan Indeks Topografi di Bretagne, Prancis

ABSTRACT. Keberadaan lahan basah merupakan sumberdaya alam yang sangat penting untuk mendukung keanekaragaman hayati. Topografi dan geomorfologi memainkan peranan penting dalam pengembangan lahan basah dan merupakan faktor pengembangan model lahan basah. Identifikasi lahan basah dapat digunakan sebagai dasar penentuan pengembangan prioritas berbasis aspek sosioekonomi dan teknis. Penelitian ini bertujuan untuk menduga luasnya potensi lahan basah pada daerah Bretagne. Untuk mengembangkan penelitian tersebut, digunakan 10 peta DAS di daerah Bretagne, Perancis. Untuk mengidentifikasi lahan basah potensial berdasarkan hidromorf tanah digunakan dengan 4 metode kriteria, yaitu: identifikasi hidromorfi, indeks perhitungan topografi, perhitungan ambang, dan validasi. Metode ambang yang digunakan antara peta lahan dan indeks topografi menunjukkan kondisi yang sama. Kita menggunakan metode ambang dan validasi dengan menggunakan 120 kombinasi peta lahan. Hasil indeks topografi adalah 4,7 dan semuanya dapat digunakan di seluruh wilayah Brittany. The Modelling Wetlands Potential Based on Topography Index in Bretagne, France ABSTRACT. Wetlands represent an important natural resource which supports natural biodiversity. Topography and geomorphology play a major role for the development of wetlands and are decisive factors for modeling wetlands extension. The importance of identifying wetlands, can be used as a basis for determining the development priorities that will be based on technical and socioeconomic aspects The objective of this research was to predict the spatial extent of potential wetlands in Brittany, France from a topographic index calibrated on a set of 10 detailed soil maps. In identifying potential wetlands, it based on soil hydromorph which conducted by method 4 criteria. The following four stages of analysis were respectively categorized: identification hidromorphy, calculation topographic index, calculation of threshold, and validation. A threshold method was conducted between soil maps and topographic index to indicate the similarity condition. We use for threshold and validation a new way using 120 combination of soil maps. The result of topographic index was 4.7 and it was applied for all Brittany

Pemodelan Lahan Basah Potensial Berdasarkan Indeks Topografi Di Bretagne, Prancis

AbstractWetlands represent an important natural resource which supports natural biodiversity. In France, in mentioned wetlands, it called potential wetlands, which have potential in its use.Topography and geomorphology play a major role for the development of wetlands and are decisive factors for modeling wetlands extension.The importance of identifying wetlands, can be used as a basis for determining the development priorities that will be based on technical and socioeconomic aspects The objective of this research was to predict the spatial extent of potential wetlands in Brittany, France from a topographic index calibrated on a set of 10 detailed soil maps. In identifying potential wetlands, it based on soil hydromorphwhich conducted by method 4 criteria. The following four stages of analysis were respectively categorized: (a) identification hidromorphy, (b) calculation topographic index, (c) calculation of threshold, (d) validation.A threshold method was conducted between soil maps and topographic index to indicate the similarity condition. We use for threshold and validation a new way using 120 combination of soil maps. The result oftopographic index was 4.7 and it was applied for all Brittany.Keywords: potential wetlands, hydromorphic soil, threshold, topographic index, spatial analysisAbstrakLahan basah merupakan sumber daya alam penting yang mendukung keanekaragaman hayati. Di Perancis dalam menyebutkan lahan basah digunakan istilah lahan basah potensial, yaitu suatu lahan basah yang memiliki potensial dalam penggunaannya. Topografi dan geomorfologi memainkan peran utama untuk pengembangan lahan basah dan merupakan faktor yang menentukan dalam pemodelan lahan basah berkelanjutan. Pentingnya mengidentifikasi lahan basah, dapat digunakan sebagai dasar untuk menentukan prioritas pembangunan yang akan didasarkan pada aspek teknis dan sosial ekonomi.Tujuan dari penelitian ini adalah untuk memprediksi luas spasial lahan basah potensial di Bretagne, Prancis dari indeks topografi dikalibrasi pada satu set 10 peta tanah rinci. Dalam mengidentifikasi lahan basah yangpotensial, berdasarkan hidromorfi tanah yang dilakukan dengan metode 4 kriteria.Penelitian ini mengacu kepada Merrot 2006 yaitu dengan metode yang sama berhasil mengidentifikasi lahan basah potensial berdasarkan indeks topografinya. Hal yang membedakan adalah jumlah peta yang digunakan yaitu 1 peta dan 10 peta, sehingga dapat dilihat apakah penelitian terdahulu memiliki nilai yang sama atau berbeda. Berikut ini empat tahap analisis yang masing-masing dikategorikan: (a) identifikasi hidromorfi, (b) indeks perhitungan topografi, (c) perhitungan ambang batas, (d) validasi. Sebuah metode ambang batas dilakukanantara peta tanah dan indeks topografi untuk menunjukkan kondisi kesamaan. Penggunaan ambang batas dan validasi merupakan pengembangan cara baru dengan menggunakan 120 kombinasi peta tanah. Hasil indeks topografi adalah 4,7 dan diterapkan untuk semua Bretagne.Kata kunci : lahan basah potensial, hidromorfi tanah, ambang batas, indeks topografi, analisis spasialDiterima: 22 Desember 2013;Disetujui: 27 Maret 201

Apport de la cartographie numérique des sols pour prédire l’hydromorphie et l’extension des zones humides potentielles à l’échelle régionale

Les outils de la Cartographie Numérique des Sols (CNS) permettent de prédire des propriétés pédologiques sur de vastes étendues à partir d’informations limitées sur les sols et de variables exhaustives traduisant les facteurs de formation des sols. L’objectif de cette étude était d’établir, à l’échelle de la région Bretagne, des cartes de prédiction de l’hydromorphie et des zones humides par apprentissage automatique, et de les valider avec des données indépendantes. La première étape a consisté à établir un modèle basé sur les relationssol-environnement physique pour prédire l’hydromorphie selon 4 classes. La méthode appliquée est une classification supervisée par arbre stochastique optimisée (algorithme AdaBoost-SAMME implémenté dans la boîte à outil ‘adabag’ du logiciel R). Le modèle a été calibré à partir de 1652 points où l’hydromorphie était connue et de 14 variables environnementales exhaustives sur la région, puis extrapolé à l’ensemble de la zone d’étude (27 360 km²). Dans une seconde étape, l’extension des zones humides potentielles a été dérivée de celle de l’hydromorphie par reclassement des valeurs prédites selon les critères pédologiques de l’arrêté du 1er octobre 2009 relatif à l’identification et à la délimitation des zones humides. Les prédictions ont été validées à partir d’informations pédologiques (données ponctuelles, cartes pédologiques précises numérisées et référentiel régional pédologique de Bretagne à 1/250 000) et d’inventaires de zones humides considérés comme fiables disponibles dans le Finistère.Les variables qui contribuent le plus au modèle de prédiction de l’hydromorphie sont l’occupation du sol, le matériau parental et la pluviométrie, suivies de la courbure verticale et de la dénivelée au cours d’eau. La précision interne du modèle est satisfaisante : le taux de prédictions correctes calculé à partir des données de calibration est de 77 %, l’indice de Kappa de 70 % et les 4 classes d’hydromorphie sont correctement prédites. La distribution spatiale des sols hydromorphes et des zones humides est très cohérente avec les connaissances préexistantes bien que l’hydromorphie et les zones humides semblent surestimées. Cette surestimation est confirmée par la validation des résultats du modèle par comparaison aux observations ponctuelles indépendantes (n =3 348) et aux cartes des sols précises : les taux de prédictions correctes sont de 55 et 36 % respectivement, et les sols non hydromorphes sont sous-estimés.Cette étude a permis d’établir une procédure complète de prédiction de l’hydromorphie et de l’extension spatiale des zones humides potentielles à l’échelle d’une région, à une résolution fine et assortie une incertitude. La procédure est répétable et adaptable, ce qui permet d’envisager d’améliorer les performances du modèle, voire de la transposer à d’autres secteurs qui disposeraient de suffisamment de données pédologiques et de variables prédictives exhaustives

Landscape design for soil conservation under land use and climate change

International audienceSoils and landscapes evolve simultaneously. Soil evolution is controlled by redistribution and transformation processes influenced by topographic and climatic parameters, with also a major contribution of management strategies. The perennial landscape features have a strong influence on soil spatial distribution (geometry) and soil genesis. Building landscapes which enhance soil resilience to degradation processes and increase soil services appears as a promising way to adapt to forthcoming climatic and land use evolutions. The presentation aims to synthetize major results from a research program nicknamed Landsoil which focused on the evolution of agricultural soils over medium time scales (decades to centuries) in relation to changing conditions of land use and climate. Precise study of the soil 3D organization in three contrasted landscapes (Brittany, Touraine, Languedoc-Roussillon) enabled to link soil redistribution in space to landscape components (field geometry, hedges or ditches network) and their past evolution. A dynamic and high resolution spatial modeling approach was developed coupling erosion processes and soil organic matter evolution and was calibrated over past evolution using dating techniques (Cs137, C14, OSL). The resulting Landsoil model was afterwards applied in a prospective manner under different scenarios of land use and climate change over the 21th century. Indicators of soil vulnerability and soil resilience were defined and tested by the comparison of several prospective scenarios applied on a same landscape and by comparison of the contrasted landscapes

Les sols bretons sont-ils menacés?

National audienceLa Bretagne a acquis en 50 ans la place de première région agricole française, notamment pour l’élevage, en intensifiant fortement ses modes de production agricole, mais également en modifiant profondément son parcellaire et son bocage. De même, elle a fortement développé ses infrastructures de transport et connaît un développement urbain important.Cette évolution s’est traduite par une augmentation des surfaces artificialisées de l’ordre de 7% entre 1990 et 2000 en Bretagne contre 5% au niveau national. De par la proportion importante de ses surfaces agricoles et urbanisées, la Bretagne se situe parmi les régions européennes où la surface relative des milieux peu anthropisés (forêts, landes, zones humides…) est la plus faible.L’impact de cette évolution récente sur les sols de Bretagne n’est pas pleinement élucidé, notamment du fait d’une insuffisance de données anciennes fiables permettant d’analyser l’évolution des sols sur plusieurs décennies. A cela s’ajoutent des difficultés métrologiques qui compliquent l’évaluation à l’échelle régionale de certaines caractéristiques du sol, notamment en matière de compaction et de biodiversité. Néanmoins, la constitution de bases de données sur les sols, mises à jour de façon régulière, permet progressivement d’affiner le diagnostic de l’état actuel des sols bretons et des principales menaces qui l’affectent