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1. Drainage Principles What is drainage? Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess water. The internal drainage of most agricultural soils can prevent severe waterlogging, but many soils need artificial drainage to improve production or manage water supplies.

2. Why drainage is importance? Drainage is importance in several keys; Flood Prevention : Proper drainage systems help manage excess rainwater and prevent flooding, which can cause extensive damage to homes, businesses, and infrastructure. Soil Health : Adequate drainage prevents waterlogging of soil, which can harm plant roots and reduce soil fertility, thereby promoting healthier plant growth and agricultural productivity. Infrastructure Protection : Effective drainage prevents water accumulation around buildings and roads, reducing the risk of structural damage, erosion, and pavement deterioration.

3. 4. Environmental Protection : Proper drainage helps manage storm water runoff, reducing the risk of pollutants being carried into rivers, lakes, and other bodies of water, thus protecting aquatic ecosystems. 5 . Erosion Control : By directing water flow, drainage systems reduce soil erosion, preserving the landscape and preventing sediment buildup in waterways 6 . Urban Management : In cities, effective drainage is crucial for maintaining public safety and preventing disruptions caused by flooding, which can impact transportation, commerce, and daily activities.

4. Types of drainage Subsurface drainage Surface drainage

5. Surface drainage is essential for managing excess water on the land surface, preventing flooding, erosion, and waterlogging. The principles of effective surface drainage involve designing and implementing systems to efficiently collect and convey surface water away from critical areas. Subsurface drainage is describes  the process of removal of that water which has infiltrated into the soil in excess of the amount that can be held by capillary forces against the force of gravity .

6. Principles of surface drainage Gravity Flow: Water naturally flows downhill due to gravity. Designing surface drainage systems to utilize natural slopes ensures efficient water removal. Creating a smooth, even surface allows water to flow unimpeded to the drainage channels. 3. Channelization : Directing water into channels, ditches, or swales helps to collect and convey it away from the surface efficiently. 4. Vegetative Cover : Maintaining or establishing vegetation helps to slow down surface runoff, reduce erosion, and increase water infiltration

7. Design elements Drainage Channels: Ditches and Swales: Shallow channels designed to collect and transport surface water. Shape and Size: Channels should be sized based on expected water volumes and shaped to maximize flow efficiency while minimizing erosion. 2. Slope and Grading: Natural Slope Utilization: Design should follow the natural topography to reduce excavation and construction costs.

8. 3. Cross Drains and Culverts Placement: Installed where water needs to pass under roads, pathways, or other obstacles Sizing : Based on the volume of water they need to carry during peak flow conditions. 4. Surface Inlets: Grated Inlets : Used in urban areas to collect water from paved surfaces Open Inlets : Used in fields and unpaved areas to allow water to enter drainage channels.

9. Applications for : Roadways Agricultural fields

10. Principles of subsurface drainage Gravity Flow : Water moves through the soil and drainage pipes primarily due to gravity. Proper slope and alignment ensure efficient water movement. 2. Hydraulic Conductivity: Soil's ability to transmit water influences drainage design. High hydraulic conductivity (sandy soils) allows for faster drainage compared to low hydraulic conductivity (clay soils). 3. Drainage Coefficient : This is the rate at which water needs to be removed, typically measured in inches or millimeters per day. It depends on factors like crop requirements, climate, and soil type.

11. Design elements 1.Drainage Pipes : Materials: Commonly made from PVC, polyethylene, or concrete. 2. Drainage Layout : Pattern: Common patterns include parallel, herringbone, and grid systems. Spacing: The distance between pipes is determined by soil type, with closer spacing for soils with low hydraulic conductivity.

12. 3. Slope and Depth : Slope: Pipes should have a minimum slope to maintain flow velocity, typically 0.1% to 1%.Depth: Depth of installation varies, but agricultural drains are often 2 to 4 feet (0.6 to 1.2 meters) deep. 4. Outlets: Drainage water is discharged at outlets, which must be protected from erosion and blockage. Outlets should have a proper freeboard and be located where they can safely dispose of water.

13. Application: FARM LAND URBAN LAND SCAPES