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Lack of appropriate agronomic practices is one of the major causes for soil erosion and low yields in teff (Eragrostis tef [Zucc.]) production in Ethiopia. A 3-yr study was conducted at the Aba Gerima watershed in northwestern Ethiopia, to investigate the effects of two tillage practices (reduced tillage [RT] and conventional tillage [CT]), two planting methods (row planting [RP] and broadcast planting [BP]), and two compaction options (with [+T] and without [–T] trampling) on soil loss and teff yields in a split-split plot arrangement. Sediment concentration ranged from 0.01 to 5.37 g L⁻¹ (mean, 0.25 g L⁻¹) in our study. Accordingly, the estimated total (August–October) soil loss ranged from 0.2 to 0.5 t ha–¹ (mean, 0.3 t ha–¹). The sediment concentration and total soil loss were significantly influenced (P

Sustainable land management (SLM) is widely recognized as the key to reducing rates of land degradation, and preventing desertification. Many efforts have been made worldwide by various stakeholders to adopt and/or develop various SLM practices. Nevertheless, a comprehensive review on the spatial distribution, prospects, and challenges of SLM practices and research is lacking. To address this gap, we gathered information from a global SLM database provided by the World Overview of Conservation Approaches and Technologies (WOCAT) and two bibliographic databases of academic research. Over 1900 SLM practices and 1181 academic research papers from 129 and 90 countries were compiled and analyzed. Relatively better SLM dissemination was observed in dry subhumid countries and countries with medium scores on the Human Development Index (HDI), whereas dissemination and research were both lower in humid countries with low HDI values. Cropland was the main land use type targeted in both dissemination and research; degradation caused by water erosion and mitigation aimed at water erosion were also the main focus areas. Other dominant land use types (e.g., grazing) and SLM purposes (e.g., economic benefits) have received relatively less research attention compared to their dissemination. Overall, over 75 % of the 60 countries experiencing high soil erosion rates (>10 t ha-1 yr-1) also have low HDI scores, as well as poor SLM dissemination and research implying the limited evidence-based SLM dissemination in these countries. The limitation of research evidence can be addressed in the short term through integrating existing scientific research and SLM databases by adopting the proposed Research Evidence for SLM framework. There is, however, a great need for additional detailed studies of country-specific SLM challenges and prospects to create appropriate evidence-based SLM dissemination strategies to achieve multiple SLM benefits. ispartof: SCIENCE OF THE TOTAL ENVIRONMENT vol:858 issue:Pt 3 ispartof: location:Netherlands status: published

This study aims to investigate the effects of polyacrylamide (PAM) alone or integrated with other soil amendments on soil fertility and Teff (Eragrostis tef (Zucc.) Trotter) yield. A field experiment was carried out for 2 years in three contrasting agroecological zones of the Upper Blue Nile basin, Ethiopia, using a randomized complete block design with 3 replicates. The amendments applied were PAM (40 kg ha−1), biochar (B, 8 t ha−1), lime (L, 4 t ha−1), gypsum (G, 5 t ha−1), farmyard manure (FYM, 5 t ha−1), PAM + B, PAM + L, and PAM + G, and control. The results showed that PAM + L, PAM + B, and L treatments noticeably improved pH, available phosphorus (Pav), total nitrogen (TN), organic carbon, and water infiltration in the Aba Gerima and Guder soils, whereas the PAM + B, B, and FYM treatments expressively increased soil water content, Pav, and TN in the Dibatie soil. Likewise, compared with the control, teff yield significantly (p

Cover management and support practices largely control the magnitude and variability of soil erosion. Although soil erosion models account for their importance (particularly by C- and P-factors in the Revised Universal Soil Loss Equation), obtaining spatially explicit quantitative field data on these factors remains challenging. Hence, also our insight into the effects of soil conservation measures at larger spatial scales remains limited. We analyzed the variation in C- and P-factors caused by human activities and climatic variables by reviewing 255 published articles reporting measured or calculated C- and P-factor values. We found a wide variation in both factor values across climatic zones, land use or cover types, and support practices. The average C-factor values decreased from arid (0.26) to humid (0.15) climates, whereas the average P-factor values increased (from 0.33 to 0.47, respectively). Thus, support practices reduce soil loss more effectively in drylands and drought-prone areas. The global average C-factor varies by one order of magnitude from cropland (0.34) to forest (0.03). Among the major crops, the average C-factor was highest for maize (0.42) followed by potato (0.40), among the major orchard crops, it was highest for olive (0.31), followed by vineyards (0.26). The P-factor ranged from 0.62 for contouring in cropland plots to 0.19 for trenches in uncultivated land. The C-factor results indicate that cultivated lands requiring intensive site preparation and weeding are most vulnerable to soil loss by sheet and rill erosion. The low P-factor for trenches, reduced tillage cultivation, and terraces suggests that significantly decreased soil loss is possible by implementing more efficient management practices. These results improve our understanding of the variation in C- and P-factors and support large-scale integrated catchment management interventions by applying soil erosion models where it is difficult to empirically determine the impact of particular land use or cover types and support practices: the datasets compiled in this study can support further modeling and land management attempts in different countries and geographic regions.

Study region: Robit-Bata watershed, Upper Blue Nile basin, Ethiopia. Study focus: Stable isotopes of water (Oxygen-18 and Deuterium) were used as tracers to estimate the contribution of groundwater in shallow hillslope aquifers to streamflow in the Robit-Bata watershed. To assess the spatiotemporal variability of shallow groundwater and develop a hydrograph separation technique, we collected rainfall, shallow groundwater, and streamflow samples and analyzed their δ18O and δ2H isotopic compositions. The local meteoric water line (LMWL) and local evaporative line (LEL) of the study area were determined and compared with the global meteoric water line (GMWL). A standard unweighted two-component isotope-based hydrograph separation model was used to determine the percentage contribution of shallow groundwater to streamflow. New hydrological insights for the region: The LMWL (δ2H = 8.63·δ18O + 18.2) mostly showed heavy isotopic enrichment relative to GMWL, and the LEL (δ2H = 5.45·δ18O + 6.96) indicated isotopic enrichment compared to Ethiopian lakes. Shallow groundwater responded rapidly to rainfall, with good spatial correlation depending on topographic positions of wells. Pre-event water contributed 90% when the watershed reached maximum storage. This finding gives insight towards the predominant runoff generation process and has significant implications for sustainable dry season irrigation expansion in the area as the sub-surface flow drains out of the watershed from October onwards reducing water tables in the shallow wells.

Gully erosion is an important sediment source and causes severe environmental degradation, particularly in the drought-prone regions of Ethiopia. We investigated the morphological characteristics of gullies, the topographic thresholds of gully formation, and estimated headcut retreat rates in three agro-ecologies of the Upper Blue Nile basin, Ethiopia: highland (Guder), midland (Aba Gerima), and lowland (Dibatie). Gully morphological characteristics were analyzed using data measured in the field, whereas the topographic thresholds were estimated using slope and upslope drainage area. Average annual linear (Rl) and volumetric (Ve) headcut retreat rates were estimated by visual interpretation of very high resolution (0.5–1.5 m) satellite images (QuickBird, IKONOS, SPOT-7, and Pleiades) in a GIS environment. A significant power relationship, fitted between gully volume (V) and length (L) for the three sites, is V = 8.097 L1.032 (R2 = 0.902, n = 94). The average annual Rl, Ve, and soil loss rates were estimated at 0.76 m yr−1, 6.77 m3 yr−1, and 8.73 t ha−1 yr−1 in Guder, 2.09 m yr−1, 19.58 m3 yr−1, and 20.76 t ha−1 yr−1 in Aba Gerima, and 3.42 m yr−1, 42.16 m3 yr−1, and 49.33 t ha−1 yr−1 in Dibatie. The higher gully headcut retreat rate in Dibatie is mainly related to the highly erodible nature of Vertisols. The coefficients of the slope (S)-drainage area (A) relationship S = aA−b were a = 0.219 and b = −0.139 in Guder, a = 0.133 and b = −0.234 in Aba Gerima, and a = 0.113 and b = −0.216 in Dibatie, indicating that topographic thresholds for gully initiation varied among the agro-ecologies. The results of this study can be used to estimate gully erosion rates and identify areas for gully initiation, thereby supporting the planning of appropriate gully control measures in the study sites and other areas with similar environmental settings.

Soil erosion by water is one of the main environmental concerns in Ethiopia. Several studies have examined this at plot and watershed scales, but no systematic study of soil erosion severity and management solutions at national scale is available. This study investigated soil erosion and the potential of land-cover- and agroecology-specific land management practices in reducing soil loss through employing the Revised Universal Soil Loss Equation and the best available datasets. The mean rate of soil loss by water erosion in Ethiopia was estimated as 16.5 t ha−1 yr−1, with an annual gross soil loss of ca. 1.9 × 109 t, of which the net soil loss was estimated as ca. 410 × 106 t (22% of the gross soil loss). Soil loss varied across land cover types, 15 agroecological zones, and 10 river basins, with the main contributors in the respective analyses being cropland (ca. 23% of Ethiopia; 50% of the soil loss; mean soil loss rate of 36.5 t ha−1 yr−1), Moist Weyna Dega (ca. 10%; 20%; 33.3 t ha−1 yr−1), and the Abay basin (ca. 15%; 30%; 32.8 t ha−1 yr−1). Our results show that ca. 25% of Ethiopia (28 × 106 ha) has soil loss rates above 10 t ha−1 yr−1, which is higher than the tolerable soil loss limits estimated for Ethiopia. Ex-ante analysis revealed that implementation of land-cover- and agroecology-specific land management practices (level bunds, graded bunds, trenches, and exclosures combined with trenches and/or bunds) in such areas could reduce the mean soil loss rate from 16.5 t ha−1 yr−1 to 5.3 t ha−1 yr−1 (mean, by ca. 68%; range, 65–70%). Suitable land management practices in the Abay and Tekeze basins and Dega and Weyna Dega agroecologies, which experience particularly severe erosion, would account for ca. 50 and 70% of the estimated soil loss reduction, respectively. This study can help raise awareness among policy makers and land managers of the extent and severity of soil loss by water erosion for better conservation planning in river basins to support sustainable use of land and water resources.

Evaluating runoff and sediment responses to human activities and climate variability is crucial for prioritizing erosion hotspots and implementing appropriate land management interventions. This study evaluated the separate and combined impacts of soil and water conservation (SWC) practices, land use/land cover, and climate variability, on runoff and sediment yield (SY) using two approaches in drought-prone watersheds of northwestern Ethiopia. In the first (paired watershed) approach, runoff and SY outputs of Kecha (treated) and Laguna (untreated) watersheds were compared. In the second approach, we compared data before and after the implementation of SWC practices in the Kecha watershed. The Soil and Water Assessment Tool (SWAT) model was adopted for both untreated and treated watersheds and used to evaluate runoff and SY responses in the two approaches. Paired watershed approach results revealed that the SWC practices reduced the surface runoff in Kecha by about 28-36% and SY by about 51-68% as compared to those in Laguna. Similarly, compared with the baseline data at Kecha, the SWC practices reduced the surface runoff and SY by about 40% and 43%, respectively, corresponding to about 65-78% of the total changes brought by changes in land use/land cover and climate variability. Hence, combining the two approaches helped reasonably estimate the reduction of surface runoff and SY due to SWC practices by about 28-40% and about 43-68%, respectively, implying that SWC practices had a considerably greater effect on SY than surface runoff. The study further revealed that the untreated Laguna watershed, where >86% of the total area is categorized as the very high soil erosion severity class, should be an immediate conservation priority. The findings of this study will be vital to devise future alternative land management scenarios in these watersheds and similar agro-ecological areas elsewhere.

Soil organic carbon (SOC) and total nitrogen (TN) are key ecological indicators of soil quality in a given landscape. Their status, especially in drought-prone landscapes, is associated mainly with the land-use type and topographic position. This study aimed to clarify the effect of land use and topographic position on SOC and TN stocks to further clarify the ecological processes occurring in the landscape. To analyze the status of SOC and TN, we collected 352 composite soil samples from three depths in the uppermost soil (0&ndash, 50 cm) in four major land-use types (bushland, cropland, grazing land, and plantation) and three topographic positions (upper, middle, and lower) at three sites: Dibatie (lowland), Aba Gerima (midland), and Guder (highland). Both SOC and TN stocks varied significantly across the land uses, topographic positions, and agro-ecosystems. SOC and TN stocks were significantly higher in bushland (166.22 Mg ha&minus, 1) and grazing lands (13.11 Mg ha&minus, 1) at Guder. The lowest SOC and TN stocks were observed in cropland (25.97 and 2.14 Mg ha&minus, 1) at Aba Gerima, which was mainly attributed to frequent and unmanaged plowing and extensive biomass removal. Compared to other land uses, plantations exhibited lower SOC and TN stocks due to poor undergrowth and overexploitation for charcoal and firewood production. Each of the three sites showed distinct characteristics in both stocks, as indicated by variations in the C/N ratios (11&ndash, 13 at Guder, 10&ndash, 21 at Aba Gerima, and 15&ndash, 18 at Dibatie). Overall, land use was shown to be an important factor influencing the SOC and TN stocks, both within and across agro-ecosystems, whereas the effect of topographic position was more pronounced across agro-ecosystems than within them. Specifically, Aba Gerima had lower SOC and TN stocks due to prolonged cultivation and unsustainable human activities, thus revealing the need for immediate land management interventions, particularly targeting croplands. In a heterogeneous environment such as the Upper Blue Nile basin, proper understanding of the interactions between land use and topographic position and their effect on SOC and TN stock is needed to design proper soil management practices.

The use of anionic polyacrylamide (PAM) as a soil conditioner could help prevent soil loss by water. In this study, we determined the effective granular PAM rate that best reduces runoff and soil loss from Oxisols. Furthermore, the effectiveness of the selected PAM rate was tested by applying it in a mixture with gypsum (G) or lime (L). The study was conducted in two phases: (i) Dry PAM rates of 0 (C), 20 kg ha&minus, 1 (P20), 40 kg ha&minus, 1 (P40), and 60 kg ha&minus, 1 (P60) were applied onto soil surface and run for six consecutive rainfall storms of 70 mm h&ndash, 1 intensity for 1 h duration, and the effective PAM rate was selected, and (ii) G (4 t ha&ndash, 1) or L (2 t ha&ndash, 1) were applied alone or mixed with the selected PAM rate. The P20 was found to be effective in reducing runoff in the beginning while P40 and P60 were more effective starting from the third storm through the end of the consecutive storms, but with no statistically significant difference between P40 and P60. Hence, P40 was selected as the most suitable rate for the given test soil and rainfall pattern. On the other hand, the mixed application of P40 with G or L increased infiltration rate (IR) in the first two storms through improving soil solution viscosity. However, effectiveness of the mixtures had diminished by various degrees as rain progressed, as compared to P40 alone, which could be attributed to the rate and properties of G and L. In conclusion, the variation in effectiveness of PAM rates in reducing runoff with storm duration could indicate that the effective rates shall be selected based on the climatic region in that lower rates for the short rains or higher rates for elongated rains. Moreover, combined application of PAM with L could offer a good option to both fairly reduce soil erosion and improve land productivity especially in acidic soils like Oxisols, which requires further field verification.

CONTEXT Teff is an important food-security crop for millions of people in Ethiopia. The demand for teff products is also increasing globally due to its health benefits as a gluten-free grain. However, teff productivity is low compared with other cereals. Crop yields vary widely among farms in rainfed production system. Identifying the key crop management practices and soil properties responsible for these variations will help to raise crop productivity through informed decision making by farmers, experts, researchers, and policy makers. OBJECTIVES The objectives of this study were to assess the characteristics of the Ethiopian teff-cropping system, quantify the variability of grain yields among farms, and identify the impacts of different crop management practices and soil fertility parameters on yield variability. METHODS The study examined 82 teff farms at three sites representing different teff-growing agro-ecologies in Ethiopia. Practices used to manage crops and soil on each farm were assessed. Composite topsoil samples were collected from farms at each site and analyzed for selected physical and chemical parameters. Grain and straw yields were quantified when crops were matured. Descriptive statistics, and factor analysis followed by multiple regression analysis was performed to identify the factors that caused the variability of yields among farms. RESULTS AND CONCLUSIONS Teff yields were highly variable within and across different agro-ecologies. The crop management factors that greatly affected yields were N and P application rates and days to harvesting. The most important soil characteristics were total nitrogen, texture and micronutrients. Poor teff yields were attributable to failure to implement improved agronomic practices, poor soil fertility, and inefficient production systems. Teff production system is a low-yielding, less-profitable, and resource-intensive enterprise. The observed variations in yields among farms indicated that there is a big opportunity to improve teff productivity. The high frequency of tillage, monocropping, and complete removal of crop residues were major causes of the low soil fertility. SIGNIFICANCE Understanding teff yield variability among farms helps to design appropriate yield improvement strategies. The use of low-cost crop-intensification options such as planting of improved cultivars using improved sowing methods, reduced tillage, incorporation of crop residues and legume-based crop rotation could sustainably improve productivity and restore soil fertility with minimal increases of costs in rainfed teff production system.

Improving our understanding of how different land uses and management practices affect soil nutrient outflows in sub-Saharan Africa could aid in developing sustainable practices. The objective of this study was to analyse the variation in outflows of soil total nitrogen (TN) and available phosphorus (Pav) as influenced by land use types (cropland, grazing land, and bushland) and land management practices (soil bunds for cropland and exclosures for non-croplands) in the three contrasting agro-ecological zones of the Upper Blue Nile basin, Ethiopia. Field data were collected for TN and Pav outflows by water erosion (Eo), leaching (Lo), product harvest (Ho), and gaseous emissions (Go) from 18 runoff plots (30 m × 6 m) for two years (2018-2019). TN and Pav losses significantly varied (p 0.05) in nutrient losses. Cropland showed significantly higher TN and Pav losses than other land use types, but TN loss did not differ significantly between grazing and bushland. In all land use types at all sites, the magnitude of nutrient losses was Ho >Eo >Lo >Go. In plots with land management practices, TN and Pav losses associated with Eo, Lo, and Go were reduced on average by 44-76%, 9-47%, and 1%-36%, respectively. These practices were most effective to reduce Eo nutrient losses. Further study is required to analyzing the soil nutrient balance and identify priority areas for implementing mitigation measures.

Ethiopia has experienced more than 10 major drought episodes since the 1970s. Evidence has shown that climate change exacerbates the situation and presents a daunting challenge to predominantly rain-fed agricultural livelihoods. The aim of this study was to analyze the extent and sources of smallholder famers&rsquo, livelihood vulnerability to climate change/variability in the Upper Blue Nile basin. We conducted a household survey (n = 391) across three distinct agroecological communities and a formative composite index of livelihood vulnerability (LVI) was constructed. The Mann&ndash, Kendall test and the standard precipitation index (SPI) were employed to analyze trends of rainfall, temperature, and drought prevalence for the period from 1982 to 2016. The communities across watersheds showed a relative difference in the overall livelihood vulnerability index. Aba Gerima (midland) was found to be more vulnerable, with a score of 0.37, while Guder (highland) had a relatively lower LVI with a 0.34 index score. Given similar exposure to climate variability and drought episodes, communities&rsquo, livelihood vulnerability was mainly attributed to their low adaptive capacity and higher sensitivity indicators. Adaptive capacity was largely constrained by a lack of participation in community-based organizations and a lack of income diversification. This study will have practical implications for policy development in heterogeneous agroecological regions for sustainable livelihood development and climate change adaptation programs.

Changes in land cover and land degradation alter natural ecosystems, thereby affecting the services these ecosystems provide. However, there have been few attempts to estimate the effects of land cover change and land degradation on ecosystem services at large spatial scales and under the strong influence of human activities. Here, we used the European Space Agency Climate Change Initiative land cover maps (1992–2015) and the value transfer valuation method to estimate the changes in ecosystem services value (ESV) in response to land cover change in sub-Saharan Africa (SSA). Moreover, we estimated the loss of ESV due to land degradation by using the long-term (1992–2015) trend in the annual normalized difference vegetation index as a proxy for long-term biomass productivity decline. Our results revealed that, between 1992 and 2015, cropland increased by about 20 million ha, largely at the expense of forest and shrubland. The total estimated ESV of SSA was about US$9 trillion year−1, of which 55% was derived from cropland and deciduous forest, with comparable contributions. Land cover change resulted in a net increase in the total ESV by US$125 billion year−1 (1992–2015), albeit with an ESV loss of US$60 billion year−1 from the conversion of evergreen forest and shrubland. Overall, cropland expansion accounted for about 60% of the increase in the total ESV (US$125 billion year−1), thereby outweighing the decrease in ESV due to the decline in natural vegetation. Land degradation hotspots covered about 5% of SSA, resulting in a total ESV loss of about US$56 billion year−1, of which nearly 65% was due to the degradation of forests and croplands. Changes in ESV varied across sub-regions, climate zones, and countries, depending on the dominant land cover change and the extent of land degradation. Our results provide useful insights for making informed decisions towards sustainable use and management of ecosystems.

Grassland degradation has profound negative impacts on ecological functions, local economic development, and social stability. Although there are many studies on the alpine grassland degradation in the Tibetan Plateau, the variation in the response of alpine meadows to degradation and restoration processes, and the underlying mechanisms remain poorly understood. To explore these issues, we selected nine grassland degradation levels along an increasing gradient at Zoige in the Tibetan Plateau, and collected vegetation and soil samples in August 2017 and 2018 to assess the state of the grassland before and after grazing exclusion (GE), respectively. The results showed that above-ground biomass (AGB), below-ground biomass (BGB), Shannon–Wiener index, soil water content (SWC), soil organic carbon (SOC), total nitrogen (STN), and total phosphorus decreased gradually with severe degrees of degradation, whereas soil bulk density and pH increased. SWC in the topsoil presented the sharpest change in slope along the degradation gradient, indicating that SWC was a sensitive indicator of alpine meadow degradation in this area. One-year GE evidently increased SWC, SOC, STN, AGB, and BGB in lightly and moderately degraded grasslands. The restoration efficiency of GE first increased and then decreased along the degradation gradient, with the turning point appearing at the third or fourth degradation level. Based on these results, we can conclude that short-term GE is an effective method for grassland restoration in this humid area, and should be performed at the shift from light to moderate degradation stages when the efficiency of recovery is the highest. These findings could facilitate a better approach for the restoration of degraded alpine meadow ecosystems.

Land use/land cover (LULC) change and climate variability are two major factors controlling hydrological responses. The present study analyzed the separate and combined effects of these two factors on annual surface runoff and evapotranspiration (ET) after validating the selected models in three drought–prone watersheds of the Upper Blue Nile basin: Kasiry (highland), Kecha (midland), and Sahi (lowland). LULC maps were produced from aerial photographs and very-high-resolution satellite images from 1982, 2005/06 and 2016/17. During 1982–2016/17 the area covered by natural vegetation showed dramatic decreases, ranging from 60.2% in Kasiry to 51.8% in Sahi. In contrast, increases in cultivated land ranged from 36.7% in Kasiry to 279.6% in Sahi; the smaller increase in Kasiry resulted from the conversion of a portion of the cultivated land to an Acacia decurrens plantation after 2006. The observed LULC changes over the study period resulted in runoff increases ranging from 4% in Kecha to 28.7% in Kasiry. Climate variability in terms of annual rainfall had no significant effect on estimated runoff; whereas both LULC change and climate variability had significant effect on estimated ET. Though climate variability increased ET from 33.6% in Kecha to 42.1% in Kasiry, the LULC change related to the reduction in natural vegetation had an offsetting effect, which led to overall decreases in ET ranging from 15.8% in Kasiry to 32.8% in Kecha watershed. As changes in LULC and climate are expected to intensify in the future, it is important to study further hydrological responses considering these changes to devise future sustainable land and water management strategies.

This study examined the trends, driving factors, and implications of land use/land cover (LULC) dynamics over the past 35 years (1982–2017) in three watersheds of the drought-prone areas that represent different agro-ecologies of Upper Blue Nile basin, Ethiopia: Guder (highland), Aba Gerima (midland), and Debatie (lowland). The changes in LULC were analyzed by integrating field observations, remote-sensing data (aerial photographs [1: 50,000 scale] and very high resolution [0.5–3.2 m] satellite images), and geographic information systems. The drivers of LULC were explored using key informant interviews and relevant literature reviews. The implications of LULC change on soil erosion and surface runoff responses were also evaluated. A minimum of four and maximum of six LULC classes were identified in each watershed over the study period. The study revealed that forest land was the dominant LULC class accounting for 40.9% and 32.0% in Guder and Aba Gerima, respectively in 1982. While in the same period, bush land (36.6%) was the dominant LULC class in Debatie watershed. From 1982 to 2016/2017, forest land, bush land, and grazing land respectively decreased by about 70%, 50%, and 27% in Guder; 65%, 49%, and 63% in Aba Gerima; and 63%, 59%, and 38% in Debatie. During the same period, cultivated land increased by approximately 40%, 129%, and 704% in Guder, Aba Gerima and Debatie, respectively. In contrast, between 2012 and 2017, plantation cover increased by about 400% in the Guder, mainly at the expense of cultivated land, which decreased by 40% for the same period. Population growth and associated changes in the farming practices were the major driving forces for the observed LULC changes in the study watersheds. The traditionally deleterious impacts of human activities on the environment have been recently reversed at an unprecedented rate, particularly at Guder and to a lesser extent at Aba Gerima, following the shift from the traditional annual cropping to more economically attractive tree-based farming practices such as Acacia decurrens plantation in Guder and khat (Catha edulis) cultivation in Aba Gerima. The continued expansion of cultivated land combined with population growth positively linked to the increase of gully erosion and surface runoff potential in the study watersheds particularly, in Aba Gerima and Debatie watersheds. The Upper Blue Nile basin is currently experiencing both positive and negative socio-economic and environmental consequences of LULC dynamics. Hence, the present study can help form a basis for the appropriate development of land management policies and strategies in this and other basins experiencing similar problems.

This chapter discusses the results of an experimental hydrological study in Dapo watershed located at the head of the upper Blue Nile Basin in Ethiopia. Detailed spatial measurements of rainfall and soil moisture were conducted at five rain gauge stations and fifteen soil moisture stations of varying depths. It was observed that there is relatively higher consistency of rainfall data in four manual rain gauge stations. Spatial and temporal distribution of soil moisture (%) shows uniform pattern of distribution at different sample depths and most of the stations showed high degree of correlation between the station values. However, unlike the soil moisture, the groundwater level at three automatic monitoring stations showed relatively differing pattern of distribution as indicated by the low degree of correlation among station values. Measurements also showed that the baseflow contribution is greater than the direct runoff contribution at the outlet of the watershed indicating streamflow generation in the watershed dominated by subsurface flow.

International audience; Morphology knowledge is relevant in language learning, information retrieval and natural language processing. Derivation lexicons are organized and comprehensive collections of the morphological variants of a language's vocabulary. These lexicons can be developed either through analysis-based synthesis of large text corpora or through synthesis of surface forms from roots, stems, lemmas and morphological rules. Much of the research attempted in developing derivation lexicon for Indo-European languages, which are concatenative, focus on analysis-based synthesis, as they do have well-developed preprocessing tools and organized text corpora. However, the methods for these languages are not appropriate for non-concatenative languages such as Semitic languages. Moreover, most of the Semitic languages, except Arabic and Hebrew, do not have well-developed text corpora and language processing tools. Hence, a novel approach that can cater for the root-pattern and rich morphology of these languages is necessary. This paper is therefore a comprehensive survey of the literature, an analysis motivating an innovative and generic morphological synthesis approach with illustrated architecture. It is part of a larger project tailored for designing an innovative, generic, approach to derivation lexicon development for Semitic languages.