Concept of multipurpose irrigation project

- A multipurpose project is one which serves more than one purpose
- Such as irrigation project can serve the following purposes.

§ Storage, control & utilization of water for irrigation.
§ Development of hydro-electric power.
§ Flood control
§ Silt control in rivers & canals
§ Inland navigation
§ Water supply
§ Fish culture
§ Recreation

- A multipurpose project entails the study of different sciences. Such as-
o Engineers
o Agriculturist
o Soil Scientists
o Hydrologist
o Meteorologist
o Administrators
o Planners
o Farmers. - Beneficiary
o Economist
o Sociologist

Considerations for development of any water resources project

1. Economic consideration:
- Cost-benefit ratio
- Cost Involves: Investigation, planning, design, construction, operation, maintenance.
- Benefits: which can be converted to money.

2. Social & economic consideration of beneficiary:
- Land ownership pattern
- Local availability of labour
- Existing farming practices facilities
- Crop type & calendar
- Transportation, storage & marketing facilities
- Banking facilities
- Technical advisory services
- Overall education level/consciousness
- Peoples participation.

3. Environmental consideration:
- EIA: Environmental Impact Assessment.
- Submergence of land & forestry
- Atmospheric pollution for organic decomposition
- Water logging
- Water borne diseases.
- Fish habitats.

Type of Irrigation Project
(A) W.r.t procurement process of water
1. Storage type
2. Diversion type
3. Combination of storage & diversion
4. River pumping.
5. Ground water pumping
6. Reclamation of wastes & sewage water

(B) W.r.t area coverage:
1. Major irrigation project: > 10,000 ha,
2. Medium irrigation project (2,000-10,000) ha
3. Minor irrigation project < 2,000 ha

(c) W.r.t purpose of the project:
1. Single purpose
2. Multipurpose.

Irrigation practice in Bangladesh:
Water management in Bangladesh involves a wide range of interventions in the country’s land and water regime but two main categories can be distinguished;
- Irrigation
- Flood control and drainage

National water policy:

Main objective is to promote agricultural growth through private development of groundwater and where feasible, with surface water development.

There are six main elements in the Government policy.
1. Encourage and promote continued development of minor irrigation without affecting drinking water supplies.
2. Encourage future ground water development for irrigation by both public and private sectors.
3. Improve resources utilization through conjunctive use of all forms of surface water and ground water for irrigation.
4. Strengthen crop diversification programs for efficient water utilization.
5. Address the problem of agricultural chemicals polluting surface water and ground water.
6. Strengthen systems of monitoring water use, water quality and ground water recharge.

Categories:
Two Categories of irrigation: minor and major irrigation
- minor irrigation is mostly by farmer-operated and owned tube-wells and low lift pumps. and 92% of the total.
- major irrigation is mostly by BWDB surface irrigation project.
- Minor irrigation is mainly done by STW.
- STW irrigation is most developed in NW, NC and SW regions.
- Surface water irrigation is mainly in NE, SE and SC regions where there is a higher density of small perennial channels and other water bodies.

Land resources:
Bangladesh has a total area of 14.7 Mha and a net cultivable land of 8.3 Mha. But at the end of 2025 this will reduce to about 7.7 Mha.

Cropping patterns:
Ø Kharif I (March to July): Pre-monsoon season. Aush is planted. Jut is also.
Ø Kharif II (July to December): The monsoon. Aman is planted.
Ø Rabi (November to April): The winter season. Boro is main crop. And others are wheat, pulses, oilseeds, vegetables etc.