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Author: Seifu Admassu Tilahun Publisher: ISBN: Category : Languages : en Pages : 206
Book Description
Despite long term efforts to reduce erosion in the Blue Nile Basin, river sediment concentrations have not declined. Lack of progress on sediment reduction indicates that runoff and erosion processes are not fully understood. The objective of this dissertation was, therefore, to understand runoff and erosion processes by investigating where runoff and erosion takes place in the landscape and to use this information to model erosion. Runoff processes were investigated in Debre Mawi, a 95-ha watershed south of Lake Tana. During the rainy period of the 2010 and 2011 monsoons, storm runoff and sediment concentrations were measured from four subwatersheds and at the main watershed outlet. In addition, perched groundwater tables, infiltration rates, rill erosion from agricultural fields and gully expansion were measured. The results show that saturation excess runoff was the main runoff mechanism because median infiltration rate was only exceeded 3% of the time. Early during rainy period, runoff produced from shallow soils upslope infiltrated before it reached the outlet, and sediment concentrations were very high as rill networks developed on the ploughed land. At the end of July, the bottom lands became saturated, the runoff coefficient at the outlet became greater than upslope areas and rill networks were fully developed reducing the velocities and thereby the sediment concentrations. A semi-distributed hillslope erosion model relating sediment concentration with overland flow using only four calibrated sediment parameters was developed based on input data from various watersheds in Blue Nile Basin. The erosion model assumed that sediment concentration is transport limiting at the beginning of the rainy phase when lands are plowed and source limited at the end. Overland flow was simulated with the semi-distributed water balance hydrology model. The model predicted daily sediment concentrations well in three small watersheds including the Debre Mawi as well as in the Blue Nile Basin at the Sudanese border. The implication of this research is that shallow degraded soils and bottom lands with gullies are the greatest sediment sources and should be targeted for erosion control.
Author: Seifu Admassu Tilahun Publisher: ISBN: Category : Languages : en Pages : 206
Book Description
Despite long term efforts to reduce erosion in the Blue Nile Basin, river sediment concentrations have not declined. Lack of progress on sediment reduction indicates that runoff and erosion processes are not fully understood. The objective of this dissertation was, therefore, to understand runoff and erosion processes by investigating where runoff and erosion takes place in the landscape and to use this information to model erosion. Runoff processes were investigated in Debre Mawi, a 95-ha watershed south of Lake Tana. During the rainy period of the 2010 and 2011 monsoons, storm runoff and sediment concentrations were measured from four subwatersheds and at the main watershed outlet. In addition, perched groundwater tables, infiltration rates, rill erosion from agricultural fields and gully expansion were measured. The results show that saturation excess runoff was the main runoff mechanism because median infiltration rate was only exceeded 3% of the time. Early during rainy period, runoff produced from shallow soils upslope infiltrated before it reached the outlet, and sediment concentrations were very high as rill networks developed on the ploughed land. At the end of July, the bottom lands became saturated, the runoff coefficient at the outlet became greater than upslope areas and rill networks were fully developed reducing the velocities and thereby the sediment concentrations. A semi-distributed hillslope erosion model relating sediment concentration with overland flow using only four calibrated sediment parameters was developed based on input data from various watersheds in Blue Nile Basin. The erosion model assumed that sediment concentration is transport limiting at the beginning of the rainy phase when lands are plowed and source limited at the end. Overland flow was simulated with the semi-distributed water balance hydrology model. The model predicted daily sediment concentrations well in three small watersheds including the Debre Mawi as well as in the Blue Nile Basin at the Sudanese border. The implication of this research is that shallow degraded soils and bottom lands with gullies are the greatest sediment sources and should be targeted for erosion control.
Author: Nigus Gabbiye Habtu Publisher: Springer Nature ISBN: 303043690X Category : Computers Languages : en Pages : 734
Book Description
This book constitutes the refereed post-conference proceedings of the 7th International Conference on Advancement of Science and Technology, ICAST 2019, which took place in Bahir Dar, Ethiopia, in August 2019. The 76 revised full papers were carefully reviewed and selected from more than 150 submissions. The papers present economic and technologic developments in modern societies in five tracks: agro-processing industries for sustainable development, water resources and environmental engineering, recent advances in electrical, electronics and computing technologies, product design, manufacturing and systems organization, and material science and engineering.
Author: Assefa M. Melesse Publisher: Springer ISBN: 3319187872 Category : Nature Languages : en Pages : 822
Book Description
The book presents the processes governing the dynamics of landscapes, soils and sediments, water and energy under different climatic regions using studies conducted in varied climatic zones including arid, semi-arid, humid and wet regions. The spatiotemporal availability of the processes and fluxes and their linkage to the environment, land, soil and water management are presented at various scales. Spatial scales including laboratory, field, watershed, river basin and regions are represented. The effect of tillage operations and land management on soil physical characteristics and soil moisture is discussed. The book has 35 chapters in seven sections: 1) Landscape and Land Cover Dynamics, 2) Rainfall-Runoff Processes, 3) Floods and Hydrological Processes 4) Groundwater Flow and Aquifer Management, 5) Sediment Dynamics and Soil Management, 6) Climate change impact on vegetation, sediment and water dynamics, and 7) Water and Watershed Management.
Author: Assefa M. Melesse Publisher: Springer Science & Business Media ISBN: 3319027204 Category : Science Languages : en Pages : 702
Book Description
The book provides a comprehensive overview of the hydrology of the Nile River, especially the ecohydrological degradation and challenges the basin is facing, the impact of climate change on water availability and the transboundary water management issues. The book includes analysis and approaches that will help provide different insights into the hydrology of this complex basin, which covers 11 countries and is home to over 300 million people. The need for water-sharing agreements that reflect the current situations of riparian countries and are based on equitable water- sharing principles is stressed in many chapters. This book explores water resource availability and quality and their trends in the basin, soil erosion and watershed degradation at different scales, water and health, land use and climate change impact, transboundary issues and water management, dams, reservoirs and lakes. The link between watershed and river water quantity and quality is discussed pointing out the importance of watershed protection for better water resource management, water accessibility, institutional set-up and policy, water demand and management. The book also presents the water sharing sticking points in relation to historical treaties and the emerging water demands of the upstream riparian countries. The need for collaboration and identification of common ground to resolve the transboundary water management issues and secure a win-win is also indicated.
Author: Fasikaw Atanaw Zimale Publisher: Springer ISBN: 3030153576 Category : Computers Languages : en Pages : 625
Book Description
This book constitutes the refereed post-conference proceedings of the 6th International Conference on Advancement of Science and Technology, ICAST 2018, which took place in Bahir Dar, Ethiopia, in October 2018. The 47 revised full papers were carefully reviewed and selected from 71 submissions. The papers present economic and technologic developments in modern societies in five tracks: agro-processing industries for sustainable development, water resources development for the shared vision in blue Nile basin, IT and computer technology innovation, recent advances in electrical and computer engineering, progresses in product design and system optimization.
Author: Haimanote Kebede Bayabil Publisher: ISBN: Category : Languages : en Pages : 296
Book Description
With the objective to ameliorate the impact of recurrent drought and severe erosion, nonindigenous soil and water conservation structures are ubiquitous in the Ethiopian highlands. Nevertheless, erosion and drought remain critical problems in the sub-humid and humid highlands. The less than optimum performance of the non-indigenous practice is caused in part by not taking the varying landscape and climate conditions into account that determine the spatial pattern of runoff and erosion and thereby the performance of soil and water conservation practices. This dissertation research was conducted with the objectives of understanding runoff generation processes and spatial and temporal runoff and erosion patterns at different (plot and watershed) scales. In addition, we investigated the potential of biochar, charcoal, and deep-rooted crops to improve soil hydraulic properties and greenhouse gas emissions. Field and laboratory experiments were conducted in the 113 ha Anjeni watershed during the 2012 and 2013 rainy monsoon phases. Field infiltration tests were conducted and soil samples were analyzed for selected soil parameters. Soil column experiments were conducted to assess the effects of biochar and charcoal amendments on moisture retention and permeability of soils. Runoff and erosion rates were measured from 24 runoff-erosion plots and at watershed outlet. In addition, gas samples were collected using static chambers and analyzed for nitrous oxide and methane emissions. Results showed that while poor soil conditions (acidic, high clay and low organic matter content) are common, saturation excess runoff was the dominant runoff mechanism. Rainfall intensity would exceed median infiltration rate only 21% of the time. Soil degradation level and tillage significantly affected runoff. Sediment concentration and yield increased with greater plot length from 3 m to 15 m, but decreased at a plot length of 30 m. Sediment rating coefficients were also affected by plot size and with the progression of the rainy monsoon phase. Wood charcoal improved permeability of soils near saturation (10 and 30 kPa). However, effect of charcoal on runoff and erosion at plot level was not significant. Significant differences were observed between seasonal nitrous oxide emissions, with greater fluxes observed during the end of the rainy monsoon phase. Overall findings of this dissertation research imply that hillslope runoff and erosion rates are greatly variable both spatially and temporally. Taking the spatial pattern and mechanisms of runoff generation into account is of paramount importance for improving the performance of newly installed soil and water conservation practices.
Author: Christian David Guzman Publisher: ISBN: Category : Languages : en Pages : 175
Book Description
Soil erosion and soil conservation are two of the biggest challenges for farmers, economic development plans, and academics in rural agricultural watersheds worldwide. This study compares erosion risk estimates and analyzes the underlying framework of models being used around the world exemplified by the Universal Soil Loss Equation (USLE) and infiltration excess runoff principles. Variations in modelled erosion processes in the Debre Mawi, Ethiopia were compared to field observations, community perceptions, and results from a saturation excess erosion model. In the first analysis, USLE did not capture the spatial representation of erosion due its misrepresentation of the main hydrological processes in humid highland watersheds: saturated pathways, subsurface flow, and gully formation. The investigation also analyzed erosion risk perceptions to better evaluate opportunities for community land management. Interviewed farmers considered themselves heterogeneous actors who have personal reservations to address before being able to work cooperatively. Also, they view government efforts as relevant but advocated more integration of farmers' ideas. Their perception of risk is based on how their lives are changing and what they anticipate will be their best for their families' future. Lastly, these insights were used to model runoff and sediment transport in this watershed with an adjusted Parameter Efficient Distributed Model. The watershed receives unpaved road flow contributions, so an integrated flow contribution needed to be represented. The added Hortonian flow adjustment to the PED model integrated both infiltration- and saturation-excess flow regimes. The discharge (NSE = 0.70) and sediment concentrations (NSE = 0.71) results on a daily scale demonstrated progress from previous work but need to better address high influxes of sediment from gullies. The results show that a more comprehensive approach to spatial distribution of erosion estimates is possible and necessary for more effective soil and water conservation in the sub humid Ethiopian Highlands. Keywords: Sediment transport, USLE, Community knowledge, Hortonian flow, Dunnean flow.
Author: R. P. C. Morgan Publisher: John Wiley & Sons ISBN: 1444328468 Category : Technology & Engineering Languages : en Pages : 608
Book Description
The movement of sediment and associated pollutants over thelandscape and into water bodies is of increasing concern withrespect to pollution control, prevention of muddy floods andenvironmental protection. In addition, the loss of soil on site hasimplications for declining agricultural productivity, loss ofbiodiversity and decreased amenity and landscape value. The fate ofsediment and the conservation of soil are important issues for landmanagers and decision-makers. In developing appropriate policiesand solutions, managers and researchers are making greater use oferosion models to characterise the processes of erosion and theirinteraction with the landscape. A study of erosion requires one to think in terms ofmicroseconds to understand the mechanics of impact of a singleraindrop on a soil surface, while landscapes form over periods ofthousands of years. These processes operate on scales ofmillimetres for single raindrops to mega-metres for continents.Erosion modelling thus covers quite a lot of ground. This bookintroduces the conceptual and mathematical frameworks used toformulate models of soil erosion and uses case studies to show howmodels are applied to a variety of purposes at a range of spatialand temporal scales. The aim is to provide land managers and otherswith the tools required to select a model appropriate to the typeand scale of erosion problem, to show what users can expect interms of accuracy of model predictions and to provide anappreciation of both the advantages and limitations of models.Problems covered include those arising from agriculture, theconstruction industry, pollution and climatic change and range inscale from farms to small and large catchments. The book will alsobe useful to students and research scientists as an up-to-datereview of the state-of-art of erosion modelling and, through aknowledge of how models are used in practice, in highlighting thegaps in knowledge that need to be filled in order to develop evenbetter models.
Author: Russell S. Harmon Publisher: Springer Science & Business Media ISBN: 1461505755 Category : Science Languages : en Pages : 120
Book Description
Landscapes are characterized by a wide variation, both spatially and temporally, of tolerance and response to natural processes and anthropogenic stress. These tolerances and responses can be analyzed through individual landscape parameters, such as soils, vegetation, water, etc., or holistically through ecosystem or watershed studies. However, such approaches are both time consuming and costly. Soil erosion and landscape evolution modeling provide a simulation environment in which both the short- and long-term consequences of land-use activities and alternative land use strategies can be compared and evaluated. Such models provide the foundation for the development of land management decision support systems. Landscape Erosion and Evolution Modeling is a state-of-the-art, interdisciplinary volume addressing the broad theme of soil erosion and landscape evolution modeling from different philosophical and technical approaches, ranging from those developed from considerations of first-principle soil/water physics and mechanics to those developed empirically according to sets of behavioral or empirical rules deriving from field observations and measurements. The validation and calibration of models through field studies is also included. This volume will be essential reading for researchers in earth, environmental and ecosystem sciences, hydrology, civil engineering, forestry, soil science, agriculture and climate change studies. In addition, it will have direct relevance to the public and private land management communities.
Author: Seifu Admassu Tilahun
Author: Seifu Admassu Tilahun
Author: Nigus Gabbiye Habtu
Author: Assefa M. Melesse
Author: Assefa M. Melesse
Author: Fasikaw Atanaw Zimale
Author: Haimanote Kebede Bayabil
Author: Christian David Guzman
Author: Lulseged Tamene Desta
Author: R. P. C. Morgan
Author: Russell S. Harmon