Topic:- Hill Slope Erosion & Its Consequences

Presented By:- Barsha Changmai Roll no.-12 Centre for Studies in Geography

MA 1st Semester Dibrugarh

University

SlopeSlope is upward or downward inclination of surface between hill and valleys and formed most significant aspect of landform assemblages.

ErosionErosion is the action of surface processes ( such as water flow or wind) that remove soil, rock or dissolve material from one location and then transport it away to another location

Introduction

Hill slope erosion

The erosion which occurs in hill slope is known as hill slope erosion. It is an important component of the complex landscape that forms a drainage.

• The entire slope profile is punctuated by the presents of convexity, concavity, rectilinearity and free face. This distinctive segments of slope profile are called slope elements or slope segments.• It is not always necessary that all the slope profile will comprise all the four elements but an ideal hill slope profile is that which consist of all the four elements.• In case of hill slope the existence of free face (cliff) element depends on the presents of resistant strata.

Element of hill slope erosion

1. Summital convexity :The convex segment is found at the hill crest (hill top) and this element is called summital convexity.

2. Free face: Free face element of hill slope represents wall-like precipitous slope of bare rocks and is devoid of any debris. The slope is so steep and precipitous that no weathered materials can rest on it.

3. Rectilinear element: The straight or linear segment of hill slope profile between upper free face and lower concave element is called rectilinear element.

4. Concave element: The basal segment of an ideal hill slope profile is always characterised by concave element the slope angle decreases as the segment of basal concavity increases(in length).

HILL SLOPE PROCESS AND EROSIONHill slope process includes those erosion process which modify slope form such as creep, overland flow rain splash, rain wash, through flow, rill and gully erosion etc.

1. Soil creep:

• It is an transportation process which facilitates mass but slow movement of moistened and loosened soil soaked with water which acts as lubricator.

• It plays major role in rounding the hill slope mainly crystal rounding and in giving convex slope from hill to crest.

2.Overland Flow

• It is also known as surface runoff

• It is an effective agent and process of slope erosion and slope modification.

3 . Rainsplash

• it is a erosion of loose superficial matters by the direct impact of falling raindrops . • The intensity of the splash erosion depends on the kinetic energy of falling raindrops. • Rainsplash becomes more effective on vegetation free slopes where falling raindrops directly hit the surface with full kinetic energy.

4.Throughflow

• It is also known as interflow.

• It refers to lateral flow of infiltrated water down the slope below slope surface.

• It is effective on densely vegetated slope because because dense vegetation allows maximum infiltration of rainwater as falling rain drops are intercepted by forest canopy and thus rainwater reaches the groundwater.

4. Rilling

• It is also known as rill and gully erosion. • it is significant mechanism of slope erosion. • Riling refers to superficial loose materials as well as rock beds through concentrated linear flow of water known as rill.• Riling is more effective on vegetation free steep slopes.• The pattern of rill depends on the steepness of slopes.• The intensity of rill erosion increases down slope.

CAUSES OF HILLSLOPE EROSION

Natural Factors Climate.

Vegetation Cover

Topography

Tectonic activity

Man Made Factors Deforestation

Shifting cultivation

Buildings of Road

Construction of Dams

Urban Development

Mining and exploration activities

CONSEQUENCES OF HILLSLOPE EROSION

1. Hillslope erosion removes valuable top soil which is the most productive part of the soil profile for agricultural purposes.

2. Many valuable trees falls.

3. House that are built along the hill are at risk of being damaged and also people may die too

4. Animals that live at the hill are at risk for the loosing homes.

5. Blocking of roads and railways.

6. It may cause production loses to open cast mines, rock quarries etc.

MEASURES TO CONTROL

HILL SLOPE EROSION

1. Afforestation.

2. Horticulture should be practised instead of shifting cultivation.

3. Controlling over grazing in hill slope.

4. By taking appropriate steps in road, bridge and dam construction.

5. Installing silt fences.

Thank You