Natural ground catchment and Open water reservoir

This category covers a range of large open water ponds that store rainwater. Natural depressions (pans) also hold rainwater in a similar way but are not modified or designed. Ponds described in this section include those that are either excavated and/or which might make use of the natural topography, and which in most cases involve an embankment around part of the pond to retain the water (the material for which may have come from excavation works). They come by different names in different countries, but names include johads and “hafirs”. These reservoirs can also be formed in existing seasonal water courses or valleys, in which case they may also be called valley dams, which are essentially the same as gully plugs (see relevant section). They can have limited to high aquifer recharge capacity – for ponds purposely built to increase groundwater recharge, see section on infiltration ponds under Managed Aquifer Recharge (MAR). This section discusses ponds constructed with the primary goal of storing surface water for various water uses (e.g. irrigation, livestock), although they may well also recharge groundwater. Ponds can be lined as well as unlined.