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close this bookRegenerative Agriculture Technologies for the Hill Farmers of Nepal: An Information Kit (IIRR, 1992, 210 p.)
close this folderNatural resources and their enhancement
View the documentOptimum Use of Marginal Land with Sgroforestry System
View the documentMultipurpose Tree Species and Their Uses
View the documentLive Fence: A Multipurpose Living Structure
View the documentTree Seed Collection
View the documentThe Forest and its Many Uses
View the documentBamboo Propagation and Management
View the documentThe Use and Conservation of Traditional Medicine Plant Resources
View the documentEthno-Veterinary Drugs: Reported Use from the Central Development Region
View the documentUnderutilized Food Crop Resources in the Midhills of Nepal
View the documentWhy Bee keeping? The Role of Bees in pollination
View the documentIntermediate Beekeeping in Nepal
View the documentImproved Terracing for Soil Conservation on Hill Farms
View the documentSmall Ponds for Water Conservation
View the documentRunoff Diversion (Mal Tarkaure) for Landslide Control
View the documentPlanning Erosion Control Measures
View the documentUnderstanding the Environment to Determine Possible Local Solutions to Soil Erosion
View the documentGully Stabilisation

Planning Erosion Control Measures

Too often, erosion control measures are either inadequate for the task they set out to perform or poorly implemented in the field. The principal reasons for this are related to poorly conceived projects and weak planning.

The decision tree (fig 1) aims to assist people in planning appropriate measures. It provides an example of the sort of issues that should be addressed before implementing works. An important idea included in the tree is the recognition that there are times when nothing can be done, either because resources are inadequate, or the hazard presented by the erosion doesn't warrant the level of resources required to arrest the problem. The tree is designed to encourage analyses of situations.

SECTION A: GUIDE TO THE DECISION TREE

1. IDENTIFICATION OF PROBLEM. The decision tree starts with a question, "What processes are causing the site to erode". To understand this, a basic understanding of both the active forces at play in the environment, and the physical properties of the site are necessary. (A diagram of site classification and appropriate solutions is presented in fig 2.) To learn something about the physical environment, watch it during the monsoon.

2. TYPE OF PROBLEM. The inter-relationship between problems that are caused by natural factors and those caused by human actions should be separated even though they are interdependent, because the type of solutions that should be applied to either are different. However, the two factors almost always need to be dealt with in rural settings.

2.A. Natural Problems. Erosion or landslide events can be subdivided into 2 categories:

(i) Deep landslides, usually greater than 250 mm in depth, during which large quantities of soil are transported down a slope. Such events often require large-scale remedies which will either be not affordable (3ai), or deemed worthwhile and given appropriate resources (3aii).

(ii) Shallow erosion resulting from surface processes with a maximum depth of 250 mm. The solutions here are often manageable, particularly if addressed early by local people using indigenous skills and resources (3aiii) and (3aiv).

2.B. Human Problems. Natural processes are altered by a variety of human activities. Poor land management and over exploitation of forest resources, or indiscriminate tipping of soil down slopes during engineering works are examples of the type of problems that can arise. They are caused by both institutional factors (2bi), and social conditions (2bii). To understand the human environment that leads to land use patterns, it is important to know who determines how resources are distributed and used. Solutions may be forthcoming, (3bi) and (3biii), or an impasse (3bii) may prevent change from occurring.

REMEMBER, do not extend the scope of the work beyond the financial, social and technical constraints. Be realistic.


A guide to planning erosion control measures