The ongoing work on modelling crop growth and water resources in the WATDEV study areas

WATDEV PhD students Samar Gomaa (Egypt) and Mulugeta Melese (Ethiopia) recently had their work plan approved by Wageningen University (Netherlands). They are making good progress with applying the SWAT-MODFLOW model to the WATDEV Ethiopian and Egyptian study sites, laying the groundwork for the subsequent application of the project’s modelling toolbox in the same areas.

SWAT-MODFLOW is well adapted to the Koga watershed study area in Ethiopia. The model domain designed by Mulugeta includes both the irrigation area, to simulate the impact of Best-Management Practices on crop production and water use; and the upstream watershed draining into the Koga reservoir, to assess available water resources for irrigation and the potential impacts of climate change. Water balance in the region adjacent to the irrigation area is also simulated, to assess the potential to use groundwater to complement the reservoir water source. Finally, the model also simulates soil erosion, sediment inflow to the Koga reservoir, and water quality, which are all processes that can affect water supplies. Mulugeta is at the moment calibrating the model using measured streamflow data, to ensure the

correct simulation of water resources.

The El-Sharkia study area in Egypt, close to the SEKEM farm, is more complex to simulate with SWAT-MODFLOW due to the artificial canals that ensure irrigation, and the dependence on water from the Nile river.

SWAT-MODFLOW model application to the irrigated areas in the El-Sharkia governorate (Egypt), applied by Samar Gomaa, including spatial domain and subdivisions, and indicating the location of the SEKEM farm

Nevertheless, Samar has managed to design the model to include the main irrigation canals and dependent areas. This will allow her to assess not only the local impact of Best Management Practices on crop production and water use but also the consequences for water demand and availability in the entire system. The Egypt model also simulates groundwater in detail, accounting for this additional source of irrigation water. At the moment, Samar is busy adapting the MODFLOW component of the integrated model to ensure that the aquifer underlying the study area is correctly simulated. 

Progress is also being made in the Sudanese and Kenyan study areas. For the Gezira study area in Sudan, WATDEV PhD student Mohammed Barsi is busy with designing his work plan, including his model application scheme. In particular, he will tackle the challenge of simulating water flow in the canal between the dam and the Gezira irrigation scheme within the SWAT-MODFLOW modelling framework using a specific hydraulic model.

Mohammed Barsi (left), Hellen Sang (centre), and João Nunes (right) in Wageningen University on 14 November 2024; the screen shows Hellen’s processed geographical data for the Tana River basin study area in Kenya

For the Tana watershed study area in Kenya, the modelling tasks have been taken over by Hellen Sang from Egerton University (Kenya). Hellen visited Wageningen University for two weeks in November 2024 and used her time to work on compiling and processing geographical and numerical data for model application together with João Nunes from ISRIC (Netherlands), and with the help of other PhD students from Wageningen. Hellen plans to apply the WATDEV modelling toolbox to the entire Tana watershed, to assess both the availability of water resources for the Tana and Bura irrigation schemes and the potential impacts of upstream water management by hydroelectric dams and water abstraction for other irrigation areas. She will return to the Netherlands in early 2025 to complete the model application.

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Ude Kebele groundwater irrigation scheme under the Adaa Becho Groundwater Irrigation system (ABGIS) in the Awash Basin

It is a new intervention area with perspectives to be expanded. It is therefore envisaged that the lessons from other countries could be scaled out in this area.

Ada’a-Becho Groundwater Irrigation (ABGIS) is located in Ada’a Wereda some 50 km from Addis Ababa. The Adama road passes nearby the scheme and has no access limitation.  This scheme is part of Ada’a-Bacho Irrigation Development Project that comprises three conjugate Kebeles (i.e., Dhankaka, Ude and Qallitty) in Ada’a District of East Shawa Zone, Oromia Regional State.

The Ude Kebele Groundwater Irrigation Site is small, scheme selected to demonstrate groundwater irrigation practice demonstration sites as it is new irrigation development area will be a learning site for a medium scale community owned groundwater irrigation development in Ethiopia.

ABGIS landscape is one of the low reliefs that slopes gently north-west and south east wards. Apart from close to the hills virtually all slopes are nearly less than 3- 4%, with the majority of the slopes of 0-2%. 

The climatic variables of the project area are highly governed by the topography of the area (mainly altitude). The highland area lies at an altitude of over 2300 m asl and covers 17.5% of the project area. Mean annual temperature of this part of the project area ranges from 12.50C to 160C.

The major crops produced include Teff, chick pea, wheat, barley, vetch, and maize.  Few farmers also produce tomato and onion as cash crops. Crop production in the area is by and large rain-dependent. But in few farmers produce vegetables twice a year using pumped water from Mojo and Waddecha rivers.

The problems in ABGIS are connected with the limited experience in fruit crop production.

Koga Irrigation System (KIS) in the Abbay Basin

KIS is an established and relatively well performing irrigation scheme in Ethiopia. In here besides Irrigation water management, there are also success stories in watershed management.

Koga is located some 40 km from Bahri Dar town (Regional capital of Amhara Regional State. The  Bahir Dar –Addis Ababa highway passes through the scheme (Fig 2), hence the scheme is year round accessible.

Koga irrigation system comprises of 19.7 km of lined main canal, 52 km of lined secondary canals, 156 km of unlined tertiary canals, 905 km of unlined quaternary canals and 11 lined Night Storage Reservoirs (NSRs). The main canal was designed to provide irrigation water for 24 h during irrigation period.

There are 12 secondary canals designed for 12 h irrigation supply each covering an area of irrigated land ranging from 220 ha to over 1000 ha. Tertiary canals are designed for 12 h irrigation supply. The area irrigated by a tertiary canal range between 20 ha to 65 ha. The quaternary canals have a capacity of irrigating 8–16 ha of land while field canals will serve an area of 2.0 ha within the quaternary unit. The maximum field canal design capacity is 30 l/s.

KIS is the best performing among many community-managed irrigation schemes. Unlike other schemes this was designed and developed as an integrated watershed and irrigation development project.

Among the problems associated to the KIS are Seasonal water shortage and associated conflicts between Irrigation water user associations, low irrigation water application efficiency, catchment degradation. In order to increase water productivity in the KIS, water saving technologies will be promoted.

The Gezira irrigation scheme

The Gezira Scheme is located between the Blue Nile and the White Nile Rivers within a semi-arid agro-climatic zone. In terms of accessibility, it is easily accessible by Wad Medani road and the trip between Wad Medani, the capital of the Gezira State and headquarter of the scheme (Barakat), and Khartoum takes about three hours. The scheme is one of the largest irrigation schemes in the region with 880,000 hectares (ha). It is one of the main sources of foreign currency (cotton export), and food security (wheat, sorghum, vegetables) for Sudan. It has huge infrastructure with a value estimated at about US $ 8 billion. The scheme had played a vital role in the history of irrigation in Sudan and Africa and has become a model for many irrigation schemes in sub-Saharan Africa in terms of design and operation system. Therefore, any research aiming at improving water management in Gezira scheme is not only beneficial to the project, but also to similar projects at national and regional scale.  There are many challenges that the scheme face and urgent need to investigate Best Management Practices (BMPs) that  can overcome these challenges and enhance productivity. Some of these challenges are deterioration of irrigation infrastructure, inefficient water distribution within the scheme, agricultural drainage discharges directly in the Blue Nile without treatment impacting water quality, institutional weakness and instability.

Belbies district

Belbies district is located 20 km south of El Zagazig city between Long. 31o 24′ and 31o 39′ E and Lat. 30o 19′ and 30o 29′ N. It is bounded at the east by Abu Hammad, at the west by Minia El Kammh and in the south by the Tenth of Ramadan City districts.

As a part of the east Nile Delta, Belbies district constitutes a portion of an arid belt of north Egypt. It is characterized by a long dry summer and short temperate winter with a rainfall period from October to March. The climate is hot in summer; the average temperature is in the range of 19.7oC and 34.7oC, while during winter it ranges from 7.4oC and 18.4oC.

Due to intensive agricultural practice, which involves the application of chemical fertilizers and pesticides, many soils and shallow aquifers are contaminated. Consequently, pollution of groundwater has become a major concern in recent years. Wastewater disposed in canals can diffuse in groundwater. Overexploitation of groundwater and intensive irrigation in major canal commands has posed serious problems for groundwater managers in Nile Delta e.g. Sharkia governorate. The development of groundwater resources, technology-oriented management skills, adequate and efficient groundwater monitoring system, empowerment of women in unprivileged areas are among the challenges to be addressed. Indeed, water management projects are one of the priority topics in the political agenda of Egypt.