Water Harvesting & Soil and Water Conservation Structures

Water harvesting -principles, importance and issues. Types of water harvesting: Rainwater Harvesting- roof tops, Micro-catchment water harvesting, Macro-catchment water harvesting, Runoff harvesting, – short-term and long-term techniques. Short-term harvesting techniques - Contour Bunds, Semicircular Hoop Trapezoidal Bunds, Graded Bunds, Rock Catchment and Ground Catchment, flood water harvesting- Permeable Rock Dams (for Crops), Water Spreading Bunds (for Crops and Rangeland), Flood Control Reservoir. Groundwater Harvesting- Qanat System.

Long-term harvesting techniques, purpose, Farm ponds: dug-out and embankment, reservoir types, tanks, earthen embankments and subsurface dykes. Farm pond components, site selection, design criteria, capacity, and control of evaporation from reservoirs.

Classification of conservation structures, functional requirements of soil erosion control structures; flow in open channels‐types of flow, state of flow, regimes of flow, energy and momentum principles, specific energy and specific force, hydraulic jump and its application, type of hydraulic jump, energy dissipation due to jump, jump efficiency, relative loss of energy.

Straight drop spillway- general description, functional use, advantages and disadvantages, structural parts and functions; Box-type inlet spillways - description, functional use, advantages and disadvantages, straight apron and stilling basin outlet, structural components and functions.

Chute spillway- general description and its components, hydraulic design, energy dissipaters, design criteria of a SAF stilling basin and its limitations, Drop-inlet spillway-general description, functional use, design criteria. Seepage under the structure, equivalent fluid pressure, triangular load diagram for various flow conditions, creep line theory, uplift pressure estimation, safety against sliding, overturning, crushing and tension.