Small Earth Dams & Water Pans in Kenya-Part 1
An overview of the process of design, implementation, operation and maintenance of small earth dams and water pans.

Small dams and water pans are emerging as critical water storage structures to mitigate the adverse effects of climate change in Kenya. Following is an review of the process of designing the structures in Kenya

The process of designing, implementing and operationalizing a small earth dam or water pan follows the typical engineering project life cycle. In that regard, it starts with project design, followed by construction and lastly, operations and maintenance. The design stage comes after a request for a small dam/water pan has been made by a community or involved authority. At this point, the engineer will visit the site to gather preliminary data to use in the design process. The key data in this case include the project location, population, water sources, and soils in the area.

1. Water Demand Analysis 

Next, the engineer will perform a water demand analysis where he/she will estimate the water requirements for human, domestic and agricultural consumers in the project location, based on the population of people and animals, and available farm land in the project area. The information is projected over the life span of the small dam (Usually 20 years) and the data used to inform the estimated water consumption of the project area. This data will form the justification for the adopted size of the dam-to the extent possible, it should meet human, domestic and agricultural water demands.

Take a free online course on small earth dam/water pan design here 

Review the complete water pan design report here

2. Design of Small Earth Dams and Water Pans 

Having come up with a viable dam/pan size based on the water demand analysis, next, the engineer will proceed to design the dam. The main dam features that have to be designed include the dam freeboard, silt trap, embankment, and spillway. The dam freeboard is estimated from the size of the dam, while the silt trap size is obtained from the amount of sedimentation in the project area. The spill way is designed from the catchment runoff data, denoted by Q. Once the design of the above is complete, the engineer prepares a summary design data sheet with all the necessary information required for implementation. The practice manual for small dams and water pans is the primary resource document used in the design process in Kenya

3. Implementation and Tendering 

With the design data in place, the engineer proceeds to compile the full design report complete with a bill of quantities. The bill of quantities is the engineers estimate of the cost of the project, which is considered strongly when choosing the person to implement the project at the tendering stage. Before tendering happens, the engineer prepares tender documents. The tender documents are handed to the procurement team, who select an appropriate contractor for the job. Once awarded, the contractor will proceed to implement the project under supervision from the project engineer, who will later approve the works and issue a certificate of completion. The dam/pan is now ready for use.

Take a free online course on small earth dam/water pan design here

Buy a complete water pan design report here

4. Operation and Maintenance 

After construction and handing over, the next stage of the dam lifecycle is operating and maintaining the structure. According to the Practice Manual for Small Dams/pans in Kenya, the type of operations and maintenance on the structure will depend on the class of the dam. Here, dams are classified as either low, medium and high hazard depending on the depth of water, impounded volume and catchment area. The key areas to pay attention to include the embankment, spill way, silt trap and the reservoir. Part of dam maintenance also entails having an inspection schedule.

5. Reference Documents in the design of small dams and water pans 

Designers of small dams, Water pans are related structures often refer to various local documents in the process. The most common ones include the Practice Manual for Small dam/pans, Isohyets maps of Kenya, Rainfall intensity maps, The Farm Management Handbook and Water Master Plan. The practice manual guides the design process from water demand analysis all the way to operations and maintenance, while isohyet maps give various precipitation data required in design. The Farm Management Handbook offers valuable site data for any project location in Kenya, while the Water Master Plan is used when performing a water demand analysis.

Take a free online course on small earth dam/water pan design here

Buy the Practice Manual, Water Master Plan and other Agric. Eng. Reference docs here

6. Technical Drawings 

Designers of small dams, Water pans are related structures often refer to various local documents in the process. The most common ones include the Practice Manual for Small dam/pans, Isohyets maps of Kenya, Rainfall intensity maps, The Farm Management Handbook and Water Master Plan. The practice manual guides the design process from water demand analysis all the way to operations and maintenance, while isohyet maps give various precipitation data required in design. The Farm Management Handbook offers valuable site data for any project location in Kenya, while the Water Master Plan is used when performing a water demand analysis.

Buy 18 Technical Drawings of Dams and Water Pans here

Buy Isohyets and Rainfall Intensity Maps of Kenya here 




Environmental Impact Assessments
A review of the background, laws, procedures, tools and how to conduct EIAs in Kenya.
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