Slide 1: FFS 301 Principles of Hydrology & Watershed Management Ravines& Its Control Measures Presented By : A.Ramkumar ID NO : BSF-07-023 Course Teacher : Dr. S.V.Kottiswaran What is Ravine ?: What is Ravine ? Avery small valley Product of streamcutting erosion. Typically classified as larger in scale than gullies, although smaller than valleys Characteristic features: Characteristic features Average rainfall: monsoon 750 mm to 900 mm. Summer & winter temperature: 47 0 C & 0 0 C. Absence of vegetation Steep slopes and gullies of varying depth from a few metres to 100 m Causative factors: Causative factors 1) Natural Factors 2) Man-made Factors Natural Factors : Natural Factors 1) Constant rainfall: Monthly distribution of rainfall Rainfall intensity and run-off Rapid snowmelts 2 ) Prolonged inundation and impact of back water during high floods. Man-made Factors: Man-made Factors Improper land use Forest and grass fires Overgrazing Mining Road construction Livestock and vehicle trails Destructive logging How Ravine is Formed ?: How Ravine is Formed ? Ravine formation is the cumulative result of Indiscriminative destruction of forests or vegetation , Unplanned cultivation , Destructive grazing and Severe water erosion. Formation of Ravine: Formation of Ravine Splash Erosion Sheet Erosion Rill Erosion Gully Erosion Ravine Ravine types: Ravine types 1) Classification on the basis of their average depth : Shallow - <5m Moderately deep - 5m to 20m Deep ravines - >20m Ravine types: Ravine types U or V shaped Ravines: It can classified based on the shape of their cross-section. Both U and V shaped Ravines may be found in same channels. Ravine types: Ravine types Classification on the basis of their Shape V Shape U Shape Ravine Zones in India: Ravine Zones in India Ravines spread-3.67million hectares along the river and tributaries . It spreading at the Rate of abut 0.5% annualy. Serious ravine intrusions: Beas in Punjab ; Chambal in Madhya Pradesh , Kalisind, Banas, Morel and Gambhir in Rajasthan ; Yamuna in Uttar Pradesh ; Mahi, Sabarmati, Narmada and Tapti in Gujarat . Slide 13: State Ravine area (lakh. ha) UP 12.30 MP 6.83 Bihar 6.50 Rajasthan 4.52 Gujarat 4.00 Pune and Haryana 1.20 West Bengal 1.04 Tamil Nadu 0.62 Maharashtra 0.20 Total 37.00 Types of Control Measures: Types of Control Measures 1) Mechanical 2) Biological Mechanical Measures: Mechanical Measures 1) Check dam Boulder Check dam Loose Stone Check dam Log & Pole Check dam Mechanical Measures: Mechanical Measures 2)Contour Bund: Bunds are simply embankment like structures, constructed across the land slope on the contour is called contour bund . Mechanical Measures: Mechanical Measures 3) Gabion Structures Wire woven baskets filled with stones Adoptable : High slope & Heavy rainfall areas Slide 19: constructed across small stream to conserve stream flows with practically no submergence beyond stream course. The height of such structure is around 0.5m &normally used in the streams with width of about 10 to 15m. Mechanical Measures: Mechanical Measures 4) Percolation Tanks Embankments across natural depressions It is permanent method Percolation tank uses: Percolation tank uses Control Storm Water Flow Temporary Underground Water Storage Infiltration of Water Into Surrounding Soil Storing Water for Re-use Controlling Release of Stored Water Modular Storm Drainage Water Systems Mechanical Measures: Mechanical Measures 5) Nala Bunds Earthen embankments across nala It is permanent method Biological Measures: Biological Measures 1) Strip Planting Growing of different crops on alternate strips of ground that usually follow the contour of the land. To minimize erosion. Types of Strip planting: Types of Strip planting Slide 25: (a) Contour Strip Cropping Growing alternate strips of erosion resisting and erosion permitting crops along the contour is termed as contour strip cropping. Slide 26: (b) Field Strip Cropping Field strip cropping consists of strips of uniform width running generally perpendicular to the direction of the erosive force, but do not confirm to any contour Slide 27: c) Buffer Strip Cropping Strips of grass or legume crop laid out between contour and field strips of crops in the regular rotations It is a narrow permanent protective strip. To reduce the erosion, surface runoff &improve surface, water quality Slide 28: d) Wind Strip Cropping The strips are laid at right angles to the prevailing wind direction, irrespective of the land slope Biological Measures: Biological Measures 3) Cover crop Any annual, biennial, or perennial plant grown as a monoculture or polyculture. To improve soil fertility, soil quality, water infiltration Biological Measures: Biological Measures 4)Afforestation: Planting of trees Along the edges of the fields, the waste land and on steepy slopes to prevent soil erosion. To enhance the capacity of the soil to retain water. Increase area under forests and indiscriminate felling of trees must stop. Choice of species : Choice of species Successful Tree species : Holoptelia integrifolia (85 % survival) Dalbergia sissoo (62%) Dichostrachys nutan (88%) Dendrocalamus strictus (22%) Prosopis juliflora (88%) Acacia nilotica (42%) Azardirachta indica (48%) Aerial seeding: Aerial seeding It is a technique of sowing seeds by spraying them through aircraft . It is usually used to grow grasses & legumes . It is applied to increase vegetative cover over barren lands like ravines or burnt sites. Reducing soil erosion Choice of species : Choice of species Aerial seeding : A. catechu Dalbergia sissoo Prosopis juliflora Dendrocalamus strictus Acacia nilotica Research center for Ravine : Research center for Ravine The Central Soil & Water Conservation Research and Training Institute, Research Center. (CSWCRTIR) It was located at Vasad. It has carried out research at last25 years investigations on To control of gullies & reclamation of ravines ,especially on the banks of river Mahi in Gujarat state. References.: References. M.P.Sing, D,N Thewari (1996) Agroforestry&Wastelands. Manual of soil & water conservation practises.Gurmel sing .C.Venkataramanan. G.Sastry. B.P.Sing http://www.thisland.illinois.edu/60ways/images/ http://www.thisland.illinois.edu Slide 37: Thank uu..