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Universität Bern (2006)

Assessing Soil Erosion and Conservation in the Loess Area of Faizabad Western Tajikistan - Integrating WOCAT Methods with a GIS-based RUSLE Model

Bühlmann Erik

Titre : Assessing Soil Erosion and Conservation in the Loess Area of Faizabad Western Tajikistan - Integrating WOCAT Methods with a GIS-based RUSLE Model

Auteur : Bühlmann Erik

Etablissement de soutenance : Universität Bern

Grade : Diplomarbeit 2006

Résumé partiel
The study was conducted within the framework of the National Centre of Competence in Research (NCCR) North–South. It assesses farmer innovations for Soil and Water Conservation (SWC) in the Loess zone of Faizabad, western Tajikistan. Soil erosion by water is a major problem in the hill zone of western Tajikistan. Inappropriate land use in this area accelerates water erosion entailing soil loss and land fertility decline. Since the food crisis during the civil war in the mid-1990s, the share of people engaged in agriculture rose to almost 60 percent in Tajikistan. Until the collapse of the Soviet Union in 1991, farmers were employed in state farms, and it was not within their responsibility to choose the way of farming. Due to this lack of experience, knowledge on necessity and opportunities for sustainable land use is scarcely available. Even though considerable environmental research on the Tajik hill zone had been conducted during Soviet times and has been resumed during the past few years, empirical erosion models have not been applied. Until now, much attention has been given to monitoring of natural resources, often excluding stakeholders from the approach. To offer an effective basis for decision making, scientific information must be coupled with knowledge of local land users. The overall goal of the present study is to evaluate the effect of local SWC innovations on soil erosion, and to identify priorities for conservation on Tajik loess soils. The research questions of the thesis are : (i) Where does soil erosion occur, and to what extent do current land use practices reduce/increase it ? (ii) Can soil erosion on cropland be reduced to sustainable levels by extending local SWC innovations ? (iii) How can soil loss reduction be achieved in an efficient and cost-effective way ? (iv) Is the GIS-based RUSLE model a suitable tool for erosion risk assessment and for modelling of conservation scenarios ? (v) Is the WOCAT methodology suitable for combination with ACED and RUSLE and for the assessment and evaluation of different land use practices / SWC technologies ? The field work for this study was carried out between April and July 2005 in a 10km x 10km study area, approximately 50km east of the capital Dushanbe. Six case studies on local SWC technologies were assessed on a field-scale. Field measurements and land user interviews were conducted using WOCAT (World Overview of Conservation Approaches and Technologies) questionnaires ; in the process a special focus was given to SWC on cropland. 57 field plots (grouped into six test sites) were mapped to evaluate the main impacts on erosion. On these fields rill measurements were conducted to validate the outputs of the erosion model at a later stage of the study. Besides, land use was visually classified for the entire test area during the field stay. Information derived from digital topographic data and from high resolution satellite imagery allowed area-wide erosion risk assessment with the RUSLE (Revised Universal Soil Loss Equation) model. Moreover, integrated in a Geographic Information System (GIS), the erosion prediction model served as tool to model the potential effect of local SWC technologies on current soil loss rates. Conservation scenarios were computed, applying local SWC innovations to fields affected by soil erosion.

Annonce (NCCR)

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Page publiée le 12 février 2020