Engineering methods can be used to control soil erosion. These include check dams, retaining walls, waterways, terracing, and embankments. Check dams are small temporary or permanent dams built across channels to slow water flow and reduce erosion. Retaining walls are designed to restrain soil on steep slopes. Waterways are designed to convey runoff at non-erosive velocities to disposal points and are often lined with grass. Engineering methods physically prevent erosion through structures, while bioengineering uses plants and trees.

1. Engineering methods to control
soil erosion
Presented by:
Santosh Pathak
IAAS, Lamjung campus

2. Engineering methods
 Engineering methods deal with the physical structures that stops or try to
prevent the happening of soil erosion.
 Bioengineering is different terms than the civil engineering. Bioengineering
uses the plants or trees to prevent the soil erosion whereas civil engineering
deals about the construction of dams, walls,terrace etc.
 There are different methods of engineering for soil erosion control. They
are as follows:
a) Check dams
b) Retaining walls
c) Water ways
d) Terracing
e) Embankment
f) Spurs and soilways

3. Check dams
 A check dam is a small dam which can be either
temporary and permanent built across a minor channel,
swale, bioswale, or drainage ditch.
 They are used to slow the velocity of concentrated water
flows, a practice that helps reduce erosion.
 Check dams are typically constructed out of gravel, rock,
sandbags, logs or treated lumber, or straw bales. They are
most effective when used with other strom water,
erosion.
 These dams are usually used only in a small, open
channel that drain ten acres (0.040km²) or less ; are
usually do not exceed 2 feet high. They are also called
Jack dams.

4.  Many check dams tends to form stream pools. Under
lorow flow circumstances water either infiltrates into the
ground , evaporates , or seeps through or under the dam.
 Under high flow(flood) conditions, water flows over or
through the structure.
 Coarse and medium grained sediments from runoff
tends to be deposited behind check dams, while finer
grains are usually allowed through.
 Extra nutrients nitrogen, phosphorus, heavy metal and
floating garbages are also trapped or eliminated by the
presence of check dams, increasing their effectiveness as
water quality control measure.
 Check dams should not be used as substitute for other
sediments – trapping and erosion control measures.

5. Advantages :
 They store surface water for use both during and
after the monsoon.
 They help in ground water recharge of the area.
Recharge of water helps in raising the water table
in the area.
 Which enhances availability of water ensures
the increases of agricultural yield by multi-
cropping.
 Check dams can be used as a pisciculture.

6. Waterways
 Nepal is second richest country of water resources.
Nepal has about 45,000km of rivers. The rivers flow
from the mountains and through steep hills because
of which transportation is very difficult.
 A feasibility study of water transport had also been
carried out in Koshi, Karnali and Mahakali rivers.
 The purpose of waterways in a conservation system
is to convey runoff at non erosive velocity to a
suitable disposal point. Therefore it should be
carefully designed.
 The most satisfactory location of a waterway is in a
well vegetated natural drainage lined where the
slopes, cross section, soil and vegetation have
naturally developed to receive and carry the runoff.

7.  Artificial waterways are normally protected by grass like paspalum spp,
kikuyu, African star grass and so referred to grassed waterways.
 Grass waterways are shallow and wide to obtain the maximum spread of
water over a wide cross section. This waterways can be used in areas where
there is sufficient moisture available to sustain a good grass cover.
 Waterways should have a parabolic cross-section and be covered densely
with locally adapted grasses. The deepest cut should be between 0.5 and
1.0m.
 Before the onset of rains, the grass in the waterway must be cut so that the
flow of water can proceed smoothly without causing eddies. Fertilisers
should be applied regularly according to the requirement of the grassland.

8. Retaining walls
 Retaining are structures designed to restrain soil to
unnatural slopes. They are used to bound soils between
two different elevations often in areas of terrain
possessing undesirable slopes or in areas where
landscape needs to be shaped severly.
 Retaining wall is a structure designed and constructed
to resist the lateral pressure of soil when there is
desired change in ground elevations that exceeds the
angle repose of the soil.
 The most important consideration in proper design and
installation of retaining walls is to recognize and
counteract the tendency of the retained material to
move down slope due to gravity

9.  Retaining walls are commonly used not only for
control of erosion, but also to protect shorelines
and keep rainwater from seeping into unwanted
areas.
 They also provide soil stability in areas where
there is a risk of significant changes of ground
elevation due to earthquakes and floods.
Although retaining walls are used in the
landscape, especially where new developments
appear.
 The basic material used in the construction of
retaining walls is concrete, which is meant to
serve the function of strength and durability.
Because of their weight, and the resultant
expensive shipping costs, contractors.

10. THANK-YOU