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Soil water erosion is a major phenomenon that threatens almost all watersheds in the Mediterranean area, nowadays. The worsening of this phenomenon in Algeria affects soil capacity to ensure its ecological functions and socio-economic purposes which depend on it. Concurrently, the storage capacity of Algeria dams has considerably decreased as a result of excessive silting. The above issue motivated this study, which aims to establish mechanisms for prioritizing to improve the economic efficiency of agricultural land and the long-term viability of dams in the largest metropolitan basin of Algeria ‘Coastal Algiers 2a basin’. This basin, which is urbanized over 50% of its area, contains six large dams with a total capacity of 540 Million m³ and one of the most important agricultural zones in Algeria. Common decision support frameworks have been implemented to predict the areas that are potentially exposed to erosion and sediment deposition threatening the dam capacity using the Soil and Water Assessment Tool (SWAT) and the Revised Universal Soil Loss Equation (RUSLE). To achieve this, rainfall, climatic, hydrometric, land use, soil, digital elevation, and satellite data were used by the two spatially soil loss models. The results show a dependency between the two statistical models with respect to low, medium and high erosion risk areas and its evolution from the eastern to the western region of the watershed. Regarding the deposition of sediments at the dams, the two models only partially explain the rate of sediments observed at the level of the dams’ basins whose relative errors exceed 4%, 8%, 60%, 30% and 40% respectively for the Meurad, Bouroumi, Keddara, Boukerdane and El Hamiz dams. The canonical analysis (CC) revealed that the average slope, vegetation cover and the available water capacity in the soil of the basin are the most important parameters influencing the soil loss provided by the two models. [ABSTRACT FROM AUTHOR]

Despite the growing importance of soil and water conservation and watershed development projects as an approach to rural development and natural resource management, there has been relatively little research on devising site-specific best management practice (BMP) to check the soil erosion losses within permissible limits, especially in hilly regions. For a sustainable watershed management programme and implementation, site specific BMPs assume importance and hold the promise of making conservation planning and watershed management simpler and more effective. The study was attempted to develop a methodology to obtain BMPs, aiming to reduce the erosion losses in erosion risk areas of the northwestern Himalayas by employing Analytic Hierarchy Process (AHP). The AHP technique was employed to prioritise the potential technologies and select the BMP suitable for a particular land area. The prioritization of technologies was performed with four criteria viz. soil erosion resistance, cost, benefit, maintenance and environment friendliness of conservation measures. The soil erosion scenario of the study area located in the northwestern Himalayas was generated with each selected measure in a SWAT model using DEM, land use maps, a soil map and climate data of the study area. Then, the resultant erosion scenario of the conservation measures was compared and used for the AHP analysis. However, other criteria were assessed based on the judgement of a group of experts as well as farmers. In this study, four conservation measures, viz. Bench Terraces (BT), Vegetative Barrier (VB), Contour Farming (CF) and Zero Tillage + Live Mulch (ZL), were considered for BMP selection. Three scenarios, viz. experts' judgement, farmers' opinions and combined expert and farmer opinion, were analyzed to uncover the BMP for the different zones. The result revealed that experts and farmers unanimously preferred ZL as a BMP because of its low-cost implementation value and lower maintenance requirement while significantly controlling the erosion level as well as being environment friendly. The BT was the second most preferred technology for the study area. However, BMP was recommended for different zones having high to very severe erosion (soil loss > 10 t/ha/yr). Therefore, ZL was recommended for the areas with low altitude, whereas BT was recommended for the areas having high slopes because of its high capability for erosion control in the high slopping area. The methodology will act as a useful strategy for decision makers to prioritize the technology and recommend the best management for any region after considering suitable criteria. Future work may consider more criteria for inclusion to thus recommend the technology for a region in a more realistic way. [ABSTRACT FROM AUTHOR]

Despite the growing importance of soil and water conservation and watershed development projects as an approach to rural development and natural resource management, there has been relatively little research on devising site-specific best management practice (BMP) to check the soil erosion losses within permissible limits, especially in hilly regions. For a sustainable watershed management programme and implementation, site specific BMPs assume importance and hold the promise of making conservation planning and watershed management simpler and more effective. The study was attempted to develop a methodology to obtain BMPs, aiming to reduce the erosion losses in erosion risk areas of the northwestern Himalayas by employing Analytic Hierarchy Process (AHP). The AHP technique was employed to prioritise the potential technologies and select the BMP suitable for a particular land area. The prioritization of technologies was performed with four criteria viz. soil erosion resistance, cost, benefit, maintenance and environment friendliness of conservation measures. The soil erosion scenario of the study area located in the northwestern Himalayas was generated with each selected measure in a SWAT model using DEM, land use maps, a soil map and climate data of the study area. Then, the resultant erosion scenario of the conservation measures was compared and used for the AHP analysis. However, other criteria were assessed based on the judgement of a group of experts as well as farmers. In this study, four conservation measures, viz. Bench Terraces (BT), Vegetative Barrier (VB), Contour Farming (CF) and Zero Tillage + Live Mulch (ZL), were considered for BMP selection. Three scenarios, viz. experts’ judgement, farmers’ opinions and combined expert and farmer opinion, were analyzed to uncover the BMP for the different zones. The result revealed that experts and farmers unanimously preferred ZL as a BMP because of its low-cost implementation value and lower maintenance requirement while significantly controlling the erosion level as well as being environment friendly. The BT was the second most preferred technology for the study area. However, BMP was recommended for different zones having high to very severe erosion (soil loss > 10 t/ha/yr). Therefore, ZL was recommended for the areas with low altitude, whereas BT was recommended for the areas having high slopes because of its high capability for erosion control in the high slopping area. The methodology will act as a useful strategy for decision makers to prioritize the technology and recommend the best management for any region after considering suitable criteria. Future work may consider more criteria for inclusion to thus recommend the technology for a region in a more realistic way.

Highlights • Used postharvest monitoring data to assess feature, site, landscape scale erosion. • Vegetative cover is the dominant factor influencing erosion across all scales. • Glacial history influences erosion and vegetation dynamics at the landscape scale. • Revegetation management on low-vegetation glacial landforms may reduce erosion. Abstract Water quality in working forested watersheds is generally high, but forestry activities may cause sedimentation of surface water if best management practices (BMPs) are not implemented during harvesting. As water resources are often managed at a landscape scale (such as by ecoregion or watershed), and BMPs are often implemented at the feature scale (such as forest road or skid trail), it is imperative to understand how biophysical factors influencing erosion (e.g., slope, soil properties, rainfall, and vegetation) behave across multiple scales. Our objective was to identify which biophysical factors determine whether erosion occurs after forest harvesting in a low relief glaciated region at the feature, harvest site, and landscape scales in order to aid in BMP optimization and ecological assessment of erosion dynamics in working forested watersheds. We analyzed monitoring data from forest roads, skid trails, and log landings on spatially referenced harvest sites in Minnesota, USA collected between 2004 and 2016 to identify major erosion risk factors. Post-harvest vegetative cover levels are more important than slope, soils, and climate factors at all spatial scales for explaining the occurrence of erosion. At the landscape scale, we identified a moderate inverse relationship between mean erosion and vegetative cover levels on sites located in different ecoregions (r2 = 0.66) and a strong relationship for sites located on different glacial landforms (r2 = 0.90). Vegetative cover is a dominant factor controlling erosion occurrence after forest harvesting in low relief glaciated regions, and glacial history is an important driver of both erosion and vegetation dynamics at the landscape scale for these regions. Revegetation BMPs and harvest practices that promote revegetation should be focused on high-erosion landscapes to reduce erosion where it is most likely to occur. [ABSTRACT FROM AUTHOR]

The temporal evolution of vegetation activity on various land cover classes in the Spanish Pyrenees was analyzed. Two time series of the normalized difference vegetation index (NDVI) were used, corresponding to March (early spring) and August (the end of summer). The series were generated from Landsat TM and Landsat ETM+ images for the period 1984-2007. An increase in the NDVI in March was found for vegetated areas, and the opposite trend was found in both March and August for degraded areas (badlands and erosion risk areas). The rise in minimum temperature and the time variation of the cloud cover during the study period appears to be the most important factors explaining increased NDVI in the vegetated areas. In degraded areas, no climatic or topographic variable was associated with the negative NDVI trend, which may be related to erosion processes taking place in these regions. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]