Water from Small Dams

Chapter 1.Introduction to small dams1.1 Purpose and scope of this handbookThe purpose of this handbook is to provide a guide to communities, technicians,farmers and others who are considering developing a water source for agricultural,livestock watering or domestic purposes. Various options are discussed and thedevelopment of ponds and small earth dams covered in detail. Guidance is providedon site investigation, design, construction, maintenance and repair.The handbook also deals with other important aspects of these water projectsincluding environmental impact (the effect on nature), community participation andmanagement, legal requirements, ownership and gender issues.Since site investigations, design and construction of medium and large size earthdams require experienced engineers and should not be constructed by fieldtechnicians and farmers, they are not included in this handbook.A word of warning: It must be remembered that the construction of any dam doescarry with it a small risk of failure. If the possible collapse of any dam threatenseither property or life then experienced technical advice should be sought.1.2 Types of small damsSmall earth dams are the subject of this handbook which covers the design andconstruction of small earth dams with storage capacities up to about 10,000 cubicmetres and having embankments up to a height of about 5 metres. Small earth damscan be built manually, using animal draught, a farm tractor, a crawler or bulldozer.The three types of small earth dams seen on the front page are covered in thefollowing chapters of this handbook:1) Charco dams for almost flat land, are described in Chapter 4.2) Hillside dams for rolling and hilly land, are described in Chapter 5.3) Valley dams for seasonal water courses and valleys are described in Chapter 6.However, since the word dam is often used for almost any type of water reservoirbuilt of soil, it might to advantageous to have a look at the various types of dams.Small earth dams are often called ponds. Their water reservoirs are constructed byexcavating a depression for the water reservoir and depositing the excavated soil onthe lower side of the water reservoir as an embankment that will increase the storagevolume of the excavated water reservoir.In addition to the three types of small earth dams described in detail in this1