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 is no hydrological study 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 a nested sub-watershed; this may be due to abstractions such as irrigation and human interventions in the watershed. There is a 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.

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.

Charlotte MacAlister, hydrologist at the International Water Management Institute (IWMI) and team leader for the Nile BDC project on ‘Assessing and anticipating the consequences of innovation in rainwater management systems‘ left Ethiopia in late January. She will start working for Canada’s International Development Research Centre (IDRC).

In this interview she shares some views on her involvement in the Nile BDC , her perspective on relative successes and challenges for her work in NBDC and some advice for the final year of the project.

What range of activities have you been involved in?

I joined IWMI in Ethiopia in 2010 and started in the week of the NBDC inception meeting.

I have been involved in the program management of the ‘Nile 4’ project and generally in basin scale water resource and hydrological impact modelling. More specifically, I have been working on training and capacity building (both internally and externally), spatial analysis and modelling, the development of water resource management tools and the generation of a data archive for the Nile Basin.

What has been successful / what are you most proud of?

Quite a few things worked well:

  • Some innovations in the application of global climate data sets.
  • The distribution of free climate data for any user (not restricted to the NBDC), i.e. with open access data sets available on the web.
  • The development of high quality, robust hydrological models of the Blue Nile using real data.
  • We have built strong linkages with local research partners (e.g. the Universities of Bahir Dar, Ambo, Arba Minch) and with governmental agencies (Abay basin authorities, Tana river basin organization, Beles river basin organization, the Ministry of Water and Energy).
  • The training and support of master students who graduated. Over the course of my involvement, we had six MSc students graduate, supported by the program.
  • Initiating the spatial analysis and modeling (SAM) topic working group for cross-basin learning.

What has been most challenging, why?

The technical challenges of modelling large and mostly ungauged basins (no rain /flow or sediment gauge) meant that building the model was difficult: How can you assess impact without data?

After we set up our models, we faced another challenge: the general lack of understanding about different interventions. We have estimates and guesses about what intervention might work where but we don’t really have any measure of impact and we cannot easily use modelling effectively for that reason. What we actually need is experimenting on catchment with different practices to find out what the physical impact of interventions will be – before and after. There is no way to get around that.

As a result of the above, another challenge was the lack of any direct impact by which we could monitor change. We are expected to assess impact without implementing any intervention. If I were to do this by myself I would start with engaging on the one hand a community that wants to make changes and on the other hand another one that does not want to make changes. Over five years I would then have time to see changes and assess impact. When your job is to quantify impact, it is difficult to work in these conditions and qualitative approaches are not enough. People in the Ministry of Water and Energy want real evidence of impact, at least within a range, to see if a practice can be scaled up.

Finally, what was also challenging was the way the project was structured: Splitting the NBDC across scales rather than themes (e.g. hydrology, economics etc.) made the project organization somewhat cumbersome.

What lessons learned will you use or build upon in your next job?

First and foremost, in a project, engaging with key partners in communities and among governmental agencies from the design of the project and at the stage of defining project outcomes is key to success.

Another lesson is that we are not that much closer to appreciating and valuing each others’ perspective between social scientists and biophysical scientists.

However, I want to continue using and promoting the tools we developed; I would like to keep some relation with the SAM group. A lot of people are working on similar issues around the world. Why not share learning across them and across communities? Our lessons don’t have to be  restricted to the different Basin Development Challenges, they can also benefit communities.

Where are you headed? Will you keep working (in some capacity) with the NBDC?

I’m going to be working as senior program officer at the water and climate change division of IDRC. I will be working on water and climate change projects in Southern Africa and South Asia. It is unlikely that I will continue collaboration with the NBDC.

Any advice to the NBDC for the final year?

Focus on what is working now and on the productive relationships that have been developed. Do not be afraid to drop activities.

On 12 November 2012, 26 participants attended a  ‘symposium on modeling in the Blue Nile / Abay Basin‘. It was organized by one of the projects of the Nile Basin Development Challenge (NBDC) – the so-called N4 project on ‘Assessing and anticipating the consequences of innovation in rainwater management systems‘.

Adanech Yared (Ethiopian Institute of Water Resources) introducing her work (Credit: ILRI / Le Borgne)

Adanech Yared (Ethiopian Institute of Water Resources) introducing her work (Credit: ILRI/Le Borgne)

Building upon recent results of this project, the team invited representatives from Nile Basin Authorities, the Ministry of Water and Energy and the Nile Basin Initiative Decision Support System Office to map out existing modeling work and to identify priorities for water resource and agricultural water management modeling in the Blue Nile Basin.

Past and current experiences

The presentations from the Nile Basin (Tana and Beles sub-basin) Authorities, from the Ministry of Water and Energy, from Bahir Dar University and from the Ethiopian Institute of Water Resources highlighted a wide spectrum of experiences. These presentations were later completed by additional presentations from NBDC scientists to form a collection of experiences spanning climate modeling, hydrological modeling, crop productivity modeling, economic modeling tools. The final presentation emphasized the need to integrate biophysical and socioeconomic model outputs and kick-started the discussion among participants.

The different presentations emphasized a number of crucial common challenges preventing modeling from being more fully exploited or useful in agricultural water management and water resource modeling initiatives: the diversity of modeling tools and their inconsistent use, the lack of good quality data, the insufficient capacity to use existing modeling tools, the lack of integration of modeling outcomes in planning and implementation strategies.

Ways forward

Later in the afternoon, participants discussed the key priorities for agriculture-water and water resource modeling in the Basin, related to either:

  • Scaling issues (integrating small scale practices and large scale impacts in planning and management)
  • Data needs
  • Uptake and acceptance of model outputs
Randall Ritzema (IWMI) Introduces the project of integrating modeling approaches (Credit: ILRI/Le Borgne)

Randall Ritzema (IWMI) Introduces the project of integrating modeling approaches (Credit: ILRI/Le Borgne)

In terms of scaling, the selection of scales depends on different variables (hydrology / erosion, population, greenhouse gas emissions, economic process, spatial variability). In turn, what is to scale varies with the scale: spatial variability, system dynamics variation within t, factors such as runoff capacity. Small scale modeling works better for better characterization of an area and at any rate there is always uncertainty in modeling for planning and management.

As regards data needs, all agreed that the main challenge was how to access data. All of the group were familiar with the bottleneck in getting met data, and the generally low resolution of soil and landcover data. The group also agreed on the need to update a range of data sets including hydro data and land cover-land use. The group also discussed the problem of numerous ungauged basins in terms of met and flow data. Some potential opportunities to use remote sensed data to fill these gaps were discussed and the International Water Management Institute (IWMI) team distributed a MET data set for Ethiopia derived from the US-NCEP CFSR (Climate Forecast System of Reanaysis) global weather data set, prepared by IWMI staff and Cornell researchers to make it useable in Ethiopia.

Finally, in terms of ensuring acceptance and uptake of modeling, a number of factors play out. The first and foremost is to think about the relevance of modeling data for the target audience, but issues of data quality, modeling complexity (and its potential to be communicated clearly) also affect the acceptance. Models should not be trusted – rather their outputs should be verified before their outputs are communicated to intended end users. In order to improve uptake of modeling outputs, the participants highlighted various strategies: tailor modeling output messages to different target audiences, develop capacities (both of modelers to communicate their outputs and of end users to use them), use various communication outputs (policy briefs, face-to-face sensitization etc.) and to engage with intended audiences throughout the process.

This symposium was the first of its kind and perhaps layed the first stone on the way to a water-agriculture modeling community of practice.

Read notes from the event.

See presentations from the event.

See some pictures of the event.

The topic working group on ‘spatial analysis and modelling’ (SAM) from the Challenge Program for Water and Food (CPWF) has agreed on a partnership between the International Water Management Institute (IWMI), Cornell University and Texas A&M University on a product dealing with global climate reanalysis data.

This partnership and announced its intentions at the recent Soil and Water Technology (SWAT) 2012 conference. The product (available at this address: http://tamu-cornell.drfuka.org/) will be hosted by Texas A&M University for now.

As an upcoming paper highlights, “Obtaining representative or near real-time meteorological data to force watershed models can be difficult and time consuming. Land based stations are often too far from the point of interest to adequately represent the weather, and many have  gaps in the data series.” The Climate Forecast System Reanalysis (CFSR) global meteorological data set has the advantage of using precipitation and temperature data, which generally provide better predictions of watershed discharge than land based stations at distances greater than 10 km from the watershed center.

This data set is useful for the SAM team for hydrological modeling, in the absence of gauge data. However, the data can also be used for any other application. It requires MET parameters – a lot of other parameters were not included (see full details at: http://rda.ucar.edu/pub/cfsr.html). Daniel Fuka, PhD student from Cornell University is leading this work.

Between 7 and 13 May, 2011, the Project ‘4’ of the Nile Basin Development Challenge (NBDC) will organise a week-long workshop on modeling in the Program. The aim is to bring together the project modeling teams to discuss emerging issues and work together on current technical challenges and cross-cutting issues.

Particular issues include scales of model applications; linking productivity and economies; linking productivity and hydrology; populating the ECOSAUT model with scarce data; and specific model technicalities such as how to incorporate RMS and how to couple SWAT and WEAP.

The workshop starts with a one day field trip to Jeldu on Saturday 7th May.

One of the cross-basin exchange and learning tools used by the Challenge Program on Water and Food (CPWF) is ‘Topic Working Groups’ on different issues of interest to all the Basins.

A new Topic Working Group has just been established on Modeling and Spatial Analysis, led by An Notenbaert (ILRI Nairobi) and Charlotte MacAlister (IWMI Addis).

Why the group?

Many modelers and spatial analysts engaged in the Mekong, Ganges, Andes, Volta, Limpopo and Nile basins are grappling with similar issues: how do we get hold of and share quality information, how do we integrate bio-physical and socio-economic data, what are the best methods to fill data gaps and move across scales, how do we link different models and build feed-back loops…?

Informal discussions and ad-hoc data exchange have already added value to the development of conceptual frameworks and the initial implementation of basin level analyses. With a little extra effort and resources, these issues could be taken to the next level. We want to continue to share information, compare methods, examine and critically appraise each other’s work. We therefore propose to establish a Topic Working Group focusing on biophysical and spatial modeling.

The Group will kick-off with a meeting later this year in the Blue Nile. We envision an initial field visit followed by in-depth cross-basin discussions on issues of common interest, possibly with input from invited experts from our wider research and development networks. In this first get together we’ll focus on hydrological models, optimization and spatial analysis. Whilst we don’t intend to streamline approaches across basins, we hope to cross-fertilize and learn from each others’ varied experiences in the different basin contexts.