Special Consideration for Hill Irrigation System in Nepal
Irrigation System in Nepal
The history of irrigation
development in Nepal before 1992 shows that the irrigation system was
developed, operated, and maintained by farmers called Farmer Managed Irrigation
System (FMIS). After that, the government of Nepal has started to make efforts
for the development of irrigation infrastructures in Nepal. The irrigation
system in Nepal can be broadly divided in the following two parts:
1.
Irrigation
System in Plains
2.
Irrigation
System in Hills/ Hill Irrigation System
The irrigation system in
plains (Terai regions) is usually of canal irrigation type which consists of
diversion headworks, canal networks, and canal structures (cross drainage
structure, canal falls/drops, cross regulators, head regulators, outlets,
escapes, etc). On other hand, the hill irrigation system is a small system that
taps water from small streams & river tributaries & consists of narrow,
deep, and long canals with steep slopes. Sprinklers & drip irrigation
system are usually suitable for hilly regions of Nepal.
Specific Consideration for Hill Irrigation
System
1.
Social Arrangements
The irrigation system
adopted in hills needs to be appropriate to the culture of different ethnic
groups living in hilly regions. Junior and senior water rights should also be
kept in mind while designing irritation systems in hills. Village boundaries
may also affect the layout of the distribution network of the irrigation
system.
2.
Managerial & Institutional Constraints
If farmers in the hilly
regions lack managerial & institutional capabilities & cannot be
trained effectively within the available time period, then the distribution
system should be simplified and control structures should be minimized. The
regulating structures should be made easy to operate by local farmers.
3. Agricultural Considerations
The irrigation system
proposed should also be compatible with the type of soil present in the hilly
region. Also, the irrigation system should be suitable for the type of crops to
be cultivated in hilly areas.
4. Financial Considerations
The choice of technology,
methods of construction, type of materials to be used, etc may be restricted
due to the financial limitations.
5. Design Considerations
§ Farmers' Participation in
Engineering Design
Because of intimate familiarity
with the local conditions, farmers may better know the design flood discharge,
flood level in the river, boulders & sediments carried by the river, etc.
By providing these facts, farmers can help designers to avoid costly mistakes.
§ Field-Based Design
Decisions regarding where to place the
structure, what type of structure to be built, etc should be taken in the field
since the topography of the hilly region is affected by various factors.
§ Design Standards
Design standards while
designing structures in hill irrigation systems should be chosen wisely.
Adoption of higher design standards (structural & operational) may be
unrealistic as the structures built in hill irrigation systems are subject to
frequent landslides, rock falls, soil erosion, etc.
§ Canal Design
Large canal sections should
not be built on unstable hill slopes. Canal beds may be steep to increase the
flow velocity & thus to reduce the seepage loss via canal beds. Canal
linings may be done with locally available materials in hilly regions.
link : https://www.dhakalvivek.com.np/2022/04/hill-irrigation-system-in-Nepal.html