March 1, 2014

Examining advance time of furrow irrigation at Koga irrigation scheme in Ethiopia – A glimpse at NBDC science

Posted by Ewen Le Borgne under Books and Chapters, CRP5, East Africa, Ethiopia, IWMI, NBDC, Nile, Nile 4, Report, Water | Tags: , , , |
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This paper examines the advance time of furrow irrigation at Koga.

Koga irrigation scheme was developed to irrigate about 7004 ha. Furrow irrigation is the recommended method for the distribution of water. However, furrow irrigation has inherent inefficiencies due to deep percolation on the upper end and runoff at the lower end of the furrow. These losses depend on furrow length, furrow gradient, surface roughness, stream size and cutoff time. These factors play significant role to influence the advance time of irrigation and the operation rule of the scheme.

The experiment was conducted during 2012 irrigation season in two periods (February and April). The advance time of irrigation was monitored at three discharge rates and four furrow gradients at 90–110 m furrow length. The required discharge was measured using RBC flume. The average advance time at respective discharge rates of 0.3, 0.6 and 0.8 litre/sec range from 290–460 min, 150–437 min and 100–294 min during 1st irrigation; and 115–370 min, 78–189 min and 43–217 min during 2nd irrigation. The advance time vary greatly among the discharge rates when the furrow length increases. The advance time of water at 0.5, 1.0, 2.0 and 2.5 % gradients was 236, 181, 197 and 398 min at 1st irrigation and 163, 175, 220 and 88 min at 2nd irrigation respectively. Furrow gradients and surface irregularities result in great variation of advance time. The advance time becomes shorter when the field gets smoother during 2nd irrigation. Under non-levelled and irregular field conditions, 0.6–0.8 litre/sec application rate can be suggested to irrigate 30–40 m furrow lengths in order to improve application efficiency above 60% and to optimize the daily operation rule of the overall scheme.

The result of this study indicates the relevance of examining the furrow length, discharge and application time recommended in the feasibility study of irrigation schemes.

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See the full proceedings of the NBDC Science meeting

This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

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February 21, 2014

Understanding runoff generation processes and rainfall runoff modelling in the Meja watershed of Ethiopia – A glimpse at NBDC science

Posted by Ewen Le Borgne under Books and Chapters, CRP5, East Africa, Ethiopia, IWMI, NBDC, Nile, Nile 2, Report | Tags: , , , |
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Understanding the basic relationships between rainfall, runoff, soil moisture and ground water level are vital for an effective and sustainable water resources planning and management activities. But so far there are no hydrological studies in Meja watershed that aims to understand the watershed characteristics and runoff generation processes.

This study was conducted to understand runoff generation processes and model rainfall runoff relationship in Meja watershed having a drainage area of 96.6 km2. The watershed is one of the three research sites of International Water Management Institute (IWMI) developed in early 2010 in the upper Blue Nile Basin of Ethiopia. In the study, primary data of soil moisture, shallow ground water level, rainfall and runoff were collected from the hydrological monitoring network in the watershed. Hydrological models like HBV and RRL SMAR were configured to understand the relationship between rainfall and runoff in the watershed.

Relationships between rainfall, soil moisture, shallow ground water level and discharge were developed to understand runoff generation processes in the watershed. According to one year and three months data, there is no strong daily rainfall and runoff relationship (r2 <0.5) in Meja and Kolu which is nested sub-watershed; this may be due to abstractions such as irrigation and human interventions in the watershed. Ground water level and runoff has strong relationship (r2> 0.65) in monthly basis of Kolu nested sub-watershed but there is moderate relationship of rainfall and ground water level. There is strong linear relationship of rainfall and monthly averaged volumetric soil moisture in most layers of Meja and its nested sub-watersheds. The general relationship between runoff and monthly averaged soil moisture at different layers in Meja watershed and Kolu is strong and linear. Analysis of rainfall runoff models indicated better performance of HBV than RRL SMAR model.

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See the full proceedings of the NBDC Science meeting

This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

 

February 9, 2014

Prioritizing rainwater management strategies in the Blue Nile basin – A glimpse at NBDC science

Posted by Ewen Le Borgne under Books and Chapters, CRP5, East Africa, Ethiopia, NBDC, Nile, Nile 3, Presentation, Report | Tags: , , |
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Most farmers in the Blue Nile Basin depend on unreliable rainfed agriculture and are vulnerable to climate variability. Lack of appropriate rain water management in these areas prevents smallholders from addressing the consequences of flooding during the rainy season and droughts during the dry season. This is in turn a major contributory factor to food insecurity and poverty.

Addressing these issues entails designing, targeting and prioritizing rain water management strategies. In support of this, we developed a generic methodology for out-scaling and prioritizing interventions in agricultural systems. The methodology entails a multi-stage and iterative process of:

  1. diagnosis and selection of options,
  2. characterization of the options,
  3. identification of the recommendation domains and out-scaling potential of these options,
  4. assessing the impacts along different dimensions and on different groups of people.

This paper describes how we applied this methodology in the Blue Nile Basin. We consulted several national stakeholders and identified the ‘best-bet’ options as they are currently being promoted by the SLM program. A next step entailed the description and characterization of the options. Previous knowledge about bio-physical and socio-economic conditions influencing suitability was collated, while field studies were undertaken to increase our understanding of adoption of these options. Matching this characterization data with a spatial database allowed us to map the suitability and feasibility of rainwater management options and strategies. For the last stage, the impact assessment, we identified the most-likely-to-be-adopted strategy for each of the watersheds based on the feasibility maps. We translated this into maps compatible with the SWAT model.

Results from the impact assessment should eventually feed back into the assessment of alternative options. The framework is applicable in many different forms and settings. The steps can be gone through qualitatively in a multi-stakeholder setting while the process can also be done quantitatively. It has a wide applicability beyond the Blue Nile Basin.

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See the full proceedings of the NBDC Science meeting

This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

 

January 16, 2014

Hydrological modelling of sustainable land management interventions in the Mizewa watershed of the Blue Nile basin – A glimpse at NBDC science

Posted by Ewen Le Borgne under Books and Chapters, CRP5, East Africa, Ethiopia, IWMI, NBDC, Nile, Nile 4, Presentation, Report | Tags: , , , , , |
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The current paper discusses the use of hydrological modelling tool to understand sustainable land management interventions in the Blue Nile basin of Ethiopia.

A micro-watershed named Mizewa with a drainage area of 27 km2 in Fogera district was selected and instrumented with hydrological cycle observation networks in the year 2011. The SWAT hydrological modelling tool was used to simulate landscape-wide Soil and Water Conservation (SWC) investments.

Simulations of the selected investments modelled in this analysis suggest that improvements in infiltration, decreases in surface runoff and decreases in erosion are achievable in the watershed. Further simulations suggest that a landscape-wide approach of terrace and bund construction has the greatest effect in terms of decreasing surface runoff, decreasing sediment yield and increasing groundwater flow and shallow aquifer recharge.

A comprehensive landscape investment of terraces on slopes greater than 5% and bunds maintained on slopes less than 5% would decrease surface flow by almost 50%, increase groundwater flow by 15% and decrease sediment yield from erosion by 85%. However, constructing terraces in areas with greater than 5% slope (without constructing bunds in areas under 5% slopes) has a similar effect whereby surface flow and sediment yield decreases by 45 and 83%, respectively and groundwater flow increases by 13%. Residue management also has a significant effect on surface flow and erosion in the Mizewa watershed. Average annual surface flow decreased 17 when adopting residue management on all agricultural land and 26% when coupling terracing on steep slopes with residue management in mid-range slopes.

These analyses provide the foundation for understanding feasible outcomes given a more comprehensive investment strategy. Results stemming from the current work can be paired with household level socio-economic data in order to assess program investment alternatives taking into account household constraints to Sustainable Land and Watershed Management (SLWM) investment and maintenance on private and public lands.

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See the full proceedings of the NBDC Science meeting

This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

 

January 12, 2014

Effect of current livestock feed sourcing and feeding strategies on livestock water productivity – A glimpse at NBDC science

Posted by Ewen Le Borgne under Animal Feeding, Crop-Livestock, CRP5, East Africa, Ethiopia, ILRI, Integrated Sciences, IWMI, Livestock Challenges, Livestock-Water, NBDC, Nile, NRM, Presentation | Tags: |
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Inefficient management and use of water is unanimously the most single constraint of agricultural production of Ethiopia.

This study was conducted to assess the effect of livestock feed sourcing and feeding strategies on livestock water productivity (LWP) in mixed crop–livestock production systems of the Blue Nile Basin in Ethiopian Highlands. Three districts representing diverse agricultural farming systems were considered. Each district further stratified to different farming systems. Multi-stage stratified random sampling technique was employed to select farm households. Household survey, group discussions and plant biomass sampling were done to generate data on beneficial outputs, water depleted and feed sourcing and feeding strategies. LWP was estimated as a ratio of livestock’s beneficial outputs and services to depleted water.

The results indicated that the major feed sources were mainly from crop residues (58.5 to 78.2%), natural pasture (10.9 to 33.4%) and aftermath grazing (9.9 to 24.3%) in study farming systems. The feed source from energy dense (improved forages) was low. The feeding strategies were relatively similar among the study farming systems. No apparent difference (P>0.05) was observed in LWP within all districts among the farming systems and the value falls between USD 0.15–0.19 m-3. However, LWP difference was observed within clustered wealth status within all farming systems and lower value of LWP general observed for the poor farm households. Such differences of LWP values can be accounted for by the strategies farm households are following in feed sourcing and how water productive those feed sources are.

In the context of this work, options to improve LWP mainly involve sourcing water productive and higher quality feed.

See the presentation:

Read the paper

See the full proceedings of the NBDC Science meeting

This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

 

December 3, 2013

Evaluation of rain water management practices for sediment load reduction in the (semi) humid Blue Nile basin – A glimpse at NBDC science

Posted by Ewen Le Borgne under Books and Chapters, CRP5, Ethiopia, Nile, Nile 4, Report | Tags: , , |
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With the construction of the new Renaissance Dam at the Ethiopian Sudan border, reducing sediment load in the Blue Nile is becoming increasingly important. Past attempts of decreasing sediment concentrations have been only partially successful. In this paper, we examine the temporal distribution of sediment generation within small watersheds and systematically compare this with the observed sediment concentration at various watershed scales using the Parameter Efficient Distributed (PED) model.

The model is based on the concept that runoff and erosion are generated mainly from areas that become saturated during the rain storm. These runoff source areas consist of shallow soils over a dense hardpan or areas where the water table is close to surface. Saturated areas are also prone to gullying. Simulation of watershed evaluations indicate that most erosion occurs from degraded areas, from temporarily saturated agricultural land and from gullies in the saturated bottomlands near the river.

In addition, we found that the annual runoff and sediment concentrations increased significantly in the Blue Nile basin at the border with Sudan. The model results would indicate that rehabilitating the degraded and bare areas by planting permanent vegetation and preventing further incision by gullies would be extremely effective in decreasing the sediment concentrations. Reduced tillage would likely result in less sediment transport but would increase use of pesticides and the cattle cannot graze freely anymore. Tentatively, we conclude that decreasing upland erosion might decrease sediment concentration downstream, since there is relatively little sediment storage in the main rivers of the Blue Nile basin.

See the presentation:

Read the paper

See the full proceedings of the NBDC Science meeting

This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

 

November 26, 2013

Factors in sub-optimum performance of rural water supply systems – A glimpse at NBDC science

Posted by Ewen Le Borgne under CRP5, East Africa, Ethiopia, NBDC, Nile, Nile 4, Presentation, Report | Tags: |
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Access to safe drinking water services in the Ethiopian Highlands is one of the lowest worldwide due to failure of water supply services shortly after construction. Over hundred water supply systems were surveyed to find the underlying causes of failure and poor performance throughout the Amhara Regional State. The results show generally that systems with decision-making power at the community level during design and construction remained working longer than when the decisions were made by a central authority. In addition, the sustainability was better for water systems that were farther away from alternative water resources and contributed more cash and labour. The results of this study of the importance of decision-making at the local level in contrast to the central authority are directly applicable to the introduction of rain water management systems as shown by earlier efforts of installing rain water harvesting systems in the Ethiopian highlands.

See the presentation:

Read the paper

See the full proceedings of the NBDC Science meeting

This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

 

July 18, 2013

Nile BDC science meeting reviews emerging research findings

Posted by Ewen Le Borgne under ASSP, Crop-Livestock, CRP5, East Africa, Ethiopia, Event, ILRI, Intensification, IWMI, Livestock-Water, Markets, NBDC, Nile, NRM | Tags: , |
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Six months before its formal end as a project, the Nile Basin Development Challenge (NBDC) hosted a science meeting to share ongoing and finalised research results.

Bedasa Eba introducing his paper60 participants met on 9 and 10 July 2013 and reviewed presentations organised around four main themes:

  • Livestock and irrigation
  • Water productivity, hydrological and erosion modeling
  • Rainwater, land and water resources management
  • Institutions, adoption and marketing

In addition, 10 posters were also featured in the science meeting, mainly from PhD and MSc students working in the NBDC. Presentations and posters are online.

Key lessons and conclusions emerging were:

  • The research for development approach adopted by the NBDC and other basins in the Challenge Program for Water and Food (CPWF) is valuable but it has not been able to go as far as planned, especially in terms of getting beyond research outputs towards development outcomes. See more about this in the presentation by Doug Merrey.
  • The Development Agents’ (DA) system has been somewhat left behind but have a crucial role to play and could be revitalised by actors like NBDC to involve DA staff in transdisciplinary research projects that can help move research outputs to outcomes.
  • NBDC research tends to focus on individual or household benefits of certain rainwater management interventions but less attention has been given to collective benefits and tradeoffs between upstream and downstream communities. The debate about on-site and off-site benefits and the link with ecosystem services at landscape level remains open.
  • Similarly, competition for water resources puts the stress on a new phenomenon: it is traditionally easier to promote individual technologies rather than collectively managed schemes (with their high transaction costs). However, adding too many individual pumps in the watershed stresses water resources.

The participants also highlighted a series of research gaps that ought to be taken up by future initiatives focusing on land and rainwater management (RWM). These included: appropriate land use planning, strengthening local agencies to deal with RWM and to plan land use, identifying suitable scalable solutions that are appropriate for a given context or focusing on scalable practices and methods or approaches; improving biomass production.

Finally, they noted that NBDC science remains somewhat scattered but the evidence base collected is an important asset to carry into other initiatives that will build on the NBDC legacy.

The presentations and individual papers featured in the NBDC science meeting will be individually featured on this website – watch this space!

Read conversation notes and links to outputs from the meeting

Discover the presentations and the posters shared at the science meeting

Download the meeting proceedings.

 

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