Kotomor, Agago (northern region, Uganda

Raised road embankments with raised culverts

one variation on the use of road embankments for water storage is the use of raised road embankments with raised culverts. a raised embankment placed in the drainage path or in a depression area will retain water runoff, which can then be used in surface storage, for recharge, or to improve soil moisture. This technique is demonstrated in photo 4.10. This approach can improve grazing areas or wetlands. The culverts in these road sections are raised, and storage capacity is a function of the enclosed area and the height difference between culverts and ground level.

Road crossings used as sand dams or as water-spreading structures

When roads cross dry riverbeds or water streams, drifts (also known as low causeways, fords, or Irish bridges) are often constructed. These road crossings can help retain groundwater upstream of the road crossing and can increase bank infiltration. These structures can have multiple functions. The first obvious function is to allow road traffic to cross the dry riverbed. a drift can also double as a proxy sand dam, trapping coarse sediment behind it and creating small local aquifers that can store and retain water. fords combined with roads also stabilize the beds of seasonal rivulets. depending on the depth of the riverbed, fords will also slow subsurface flows and retain groundwater upstream. Wells or infiltration galleries can then be constructed to gain access to the water retained upstream of the ford. This capacity

PHOTO 4.10

Raised road embankment and raised culverts creating local wetland in Kotomor, Agago (northern region, Uganda)

Source: © Aidenvironment. Used with the permission of Aidenvironment. Further permission required for reuse.