A watershed is an area of land from which all the water drains to a common point into a stream, a channel, a lake, a reservoir, or other body of water.
A small watershed of a few hectares that drains into a small stream forms part of a larger
watershed, which in turn forms part of a still larger watershed, until the combined watershed may become a major river basin draining millions of square kilometers of land.
The whole basin is divided into several smaller units, such as watersheds or sub-watersheds, by considering its drainage system. Thus watersheds are composed of numerous, small units of sub-watershed which are smaller in size.
Why is sub-watershed prioritization important?
Generally, a district will have several sub-watersheds, as seen in the topographical and
drainage maps, depending upon the size of the district. Land and water resources are limited and their wide utilization is imperative where the population pressure is continuously increasing.
The watershed management concept recognizes the inter-relationships among
the linkages between uplands and low lands, land use, geomorphology, slope, and
soil. Watershed development activities cannot be carried out in all the sub-watersheds in a given time period due to financial and manpower constraints. Therefore, for efficient utilization of the available resources, sub-watershed and activities prioritization are utmost.
Watershed deterioration is a common phenomenon in most parts of the world. Among
its several causes, the major ones are improper and unwise utilization of watershed
resources without any proper vision, which is observed in developing countries like
Nepal. In order to combat and address these problems, sustainable development
is no doubt the appropriate policy strategy. Drainage basins, catchments, and sub-catchments/sub-watersheds are the fundamental units of the management of land
and water, identified as planning units for administrative purposes to conserve natural
Hence the concept of prioritization plays a key role in identifying areas that need immediate attention, based on erosion potentials and people’s pressure on land. Taking this into consideration, the DSCWM has been prioritizing sub-watersheds/ sub-projects or VDCs through an integrated approach with an objective to select sub-watersheds to undertake soil and water conservation measures in the landscape.
sub-watershed is also prioritized because of the following other reason:-
- When resources are thinly distributed, can have no significant hydrological benefit or ecological and economical advantages.
- To make impactful work done.
- For carrying out concentrated work.
Objectives of the guidelines
The overall objective of these guidelines is to develop realistic soil conservation and
watershed management plans for making efficient and effective utilization of available
The specific objectives of the guidelines are:-
- To identify suitable and simple methodologies easily adaptable by District Soil Conservation Offices and watershed management projects.
- Identify priority sub-watersheds where soil conservation and watershed management activities are needed.
- To explain and illustrate sub-watershed prioritization with examples from a district.