May 19, 2014

Consider downstream and off-site costs and benefits of land and water management interventions – NBDC key message #7

Posted by Ewen Le Borgne under CRP5, East Africa, Ethiopia, Film and Video, IWMI, NBDC, Nile, Nile 4, NRM | Tags: , , |
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In late 2013, the Nile Basin Development Challenge developed eight key messages. Taken together, these messages form a new paradigm that can help further transform policies and programs and better enable poor smallholder farmers to improve their food security, livelihoods and incomes while conserving the natural resource base.

The seventh key message from the Nile Basin Development Challenge is to ‘attend to downstream and off-site benefits of rainwater management as well as upstream or on-farm benefits and costs.’ How do land and water management interventions affect, positively or negatively, downstream and/or off-site users? Erosion and siltation management at site level has far-reaching consequences for people kilometers away from these sites. Smart land and water management interventions consider such trade-offs upfront and throughout.

See the overall digital story ‘An integrated watershed rainwater management paradigm for Ethiopia: Key messages from the NBDC‘.

Download the brief covering the full set of key messages.

Read the full technical report “A new integrated watershed rainwater management paradigm for Ethiopia: Key messages from the Nile Basin Development Challenge, 2009–2013“

This digital story was produced to communicate the key messages resulting from the Nile Basin Development Challenge (NBDC). The Nile BDC aimed to improve the livelihoods of farmers in the Ethiopian highlands through land and water management and was funded by the Challenge Program for Water and Food. The eight key messages constitute a ‘new integrated watershed rainwater management paradigm’ and are based on the outputs and outcomes of trans-disciplinary scientific research for development

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April 10, 2014

On-site financial costs of soil erosion by runoff from the Mizewa catchment 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, NRM, Report | Tags: , |
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This study was conducted in Mizewa watershed which is located in Blue Nile Basin (BNB) to estimate on-site financial cost of erosion in terms of yield reduction taking maize as representative crop. For this purpose, discharge measurement and runoff sampling was made during the rainy season of 2011 at the outlet of three sub watersheds within Mizewa catchment; lower Mizewa (MZ0), Upper Mizewa (MZ1) and Gindenewur (GN0).

The samples were filtered to separate the sediment which was subsampled for determination of suspended sediment concentration (SSC), sediment fixed NO3 -, NH4 + and available phosphorous (P) contents. The filtered water was used to assess dissolved nitrate and dissolved phosphate. The on-site financial cost of erosion was estimated based on productivity change approach (PCA) focusing on available NP losses.

The result revealed that the SSC and its NP content varied in space and time, in which higher and lower SSC occurred towards the beginning and end of the rainy season, respectively. The mean seasonal discharge was found to be 2.12±0.75, 1.49±0.52 and 0.57±0.20 m3/ sec at MZ0, MZ1 and GN0 stations in that order while the corresponding sediment concentration was 510±370 mg/l, 230±190 mg/l and 370±220 mg/l. This led to the total suspended sediment loss (SSL) of 4 ton/ha/year, 2 ton/ha/year and 3 ton/ha/year from the respective subwatersheds. The on-site financial cost due to N and P lost associated with SSL was estimated to be USD 200/ha, USD 186/ha and USD 227/ha from MZ0, MZ1 and GN0 watersheds, respectively.

The study revealed that the economic impacts of soil erosion which is variable based on the characteristics of land resources and management practices are immense and deserve due attention. The result may help in sensitizing both farmers and decision-makers about the risk of soil erosion and in targeting management practices to overcome the challenges.

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.

 

March 9, 2014

Characteristics and on-site financial costs of erosion in the Meja watershed of the Abay basin, 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 | Tags: , , , , |
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Most soil erosion studies conducted in Ethiopia are focused on quantification of sediment and lack specific information on temporal and spatial variability of sediment and its associated plant nutrients loss. This study was therefore quantified and characterized runoff and sediment along with estimated the on-site financial cost of erosion in terms of its concomitant crop yield loss due to the nitrogen and phosphorus lost in consequence of erosion.

Data on discharge and runoff samples for sediment concentration and nutrient content was collected at three monitoring stations (Melka, Galesssa and Kollu) in Meja watershed in Jeldu district, in the Ethiopian part of the Blue Nile Basin. Daily samples collected during the rainy season were analysed in the laboratory of Ambo University for sediment content of runoff, particle size distribution of the sediment and nitrogen and phosphorus content of both the sediment and runoff. Preliminary results indicate that both runoff volume and sediment concentration vary with space and time. While the maximum runoff volume was recorded in the middle of the rainy season, sediment concentration decreased towards the end of the rainy season in response to increased ground cover. The average suspended sediment concentration during the rainy season was 3.0 ± 1.1, 2.2 ±1.3 and 1.4 ± 0.9 g L-1 while the total sediment yield ranged from 74 t km-2, 248 t km-2 and 604 t km-2 at Melka, Galesssa and Kollu, respectively. The financial cost of erosion was estimated at 595, 510 and 2475 ETB ha-1 from Melka, Kollu and Galessa, respectively.

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 27, 2013

Erosion modeling in the Upper Blue Nile Basin – The case for Mizewa Watershed – 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 main objective of this research was to study soil erosion and sediment yield in Mizewa watershed using SWAT model.

The study involved hydrological and erosion modelling using primary data collected in the watershed. Hydrological and meteorological data were collected from the stations installed in the watershed by the International Water Management Institute (IWMI) in collaboration with the Ministry of Water and Energy and the National Meteorological Service Agency.

Suspended sediment data was collected at Mizewa River in the watershed, used for sediment rating curve development. The land use/ land cover map was prepared using field survey and Land Sat image and the soil map for the watershed was prepared from Abay basin soil as per the United Nations’ Organisation for Food and Agriculture (FAO)’s world soil database.

The average monthly soil loss was estimated in July with pick suspended sediment concentration despite the pick flow and sediment yield at the outlet being recorded in August – which is believed to happen due to the sediment data developed by the sediment rating curve. The predicted rate of soil loss and sediment yield at the subbasins and watershed outlet were high, leading to consider the watershed as an erosion-sensitive area according to Setegn (2009) and Hurni (1985)’s criteria of erosion sensitivity.

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.