Design of contour bunds pdf

Contour bunds in deep black soils have been a failure because of the nature of soil, which cracks during hot weather and cakes during the monsoon. Background water spreading bunds are often applied in situations where trapezoidal bunds are not suitable, usually where runoff discharges are high and would damage trapezoidal bunds or where the crops to be grown are susceptible to the temporary waterlogging, which is a characteristic of trapezoidal bunds. Paddy rice grows best when its roots are submerged in water and so basin irrigation is the best method to use for this crop figure 7. Contour bunds are preferred for construction in areas receiving annual rainfall less than 600 mm and where soil moisture is a limiting factor for crop production. Artificial swales are often infiltration basins, designed to manage water runoff, filter pollutants, and increase rainwater infiltration. Efficiency of contour bunds on soil, runoff and nutrient losses under selected agricultural landuse types the trends in soil and runoff losses from major agricultural landuses, after introduction of contour bunds, are given in the figures 3 and 4 respectively.

It retains the running off water in the watershed and thus to helps to control soil erosion. At its simplest, contour trench construction is an extension of the practice of plowing fields at a right angle to the slope. Due to their halfmoon design, semicircular bunds are well suited for planting individual trees. The following parameters should be considered for bund design. However, in reality, the ability of a contour bank to carry this design runoff is largely dependent on the condition of the channel at the time the runoff event. Stone pitched contour bund this measure involves construction of horizontal lines of stone pitched contour bunds across the sloping land surface. Contour bunds are constructed in relatively low rainfall areas having annual rainfall of less than 600 mm. Along bunds trees which fixes nitrogen in to the soil are planted with grass along the bunds. The first attempts at water harvesting, based on contour bunds, were not well designed or supervised. Chapter 7 discusses under which circumstances to choose basin irrigation.

The mechanical measures include contour bund, graded bund, terraceing and contour stonewall etc. These techniques help to capture and hold rainfall before it can become runoff. If bunds are formed in a terracelike design, the labour required. For high rainfall areas, the design of bunds depends upon the depth of water impounded. The operator should walk the line of the bund and set out the line with marker canes. Contour stone bunding detail of stone bund section 4. Bunds sswm find tools for sustainable sanitation and. Bund spacing should not be so wide as to cause excessive soil erosion between. Pdf nomogrpahs for graded bund design in heavy soils. Nala bunds are constructed across bigger streams of second order in areas having gentler slopes. O ne of the first activities that should be performed at a project site is a site assessment of resource issues. One such measure, the use of stone bunds built on natural contour lines, has been promoted and supported by governments, ngos, extension agents and farmers for more. Rice cultures are the best known example of contour bunds.

I have worked on few heavily contoured sites myself. Contour bunding is practiced to intercept the runoff flowing down the slope by an embankment with either open or closed ends to conserve moisture as well as to reduce erosion. Design of the tank shape depends on the soil type, which dictates the maximum possible slope that will stay in place without falling in. Bund spacing is expressed as the vertical or the horizontal distance between corresponding points on two adjacent bunds. The spacing of bunds is so arranged that the flowing water. Leveltier benefits costs to the farmers financial benefits overall soil improvement societal benefits higher yield land portion for structures contribution 10% of total cost to the watershed development authority implementation and experimenting of tech. A small channel on the inside of the bunds is made to let the water run along. Identification of watershed benefits and costs identification of watershed benefits and costs. A policy of foodforwork had followed the free distribution of food at the beginning of the crisis. Farm bunds are constructed on agricultural land with the aim of arresting soil erosion and improving the soil moisture profile. The bund should aim to follow a set contour to maintain a fixed height along the top of the bund. Trapezoidal bunds were designed for turkana district when a widespread food relief operation was underway in 1984.

For easy supervision of the upper side of the dam a road is built originating from and in contour line with the crust of the dam. Assessment of contour bunding technology for improved land and water management in mali technical document produced for the cgiar program on water, land and ecosystem wle birhanu zemadim, ramadjita tabo, bougouna sogoba, fourtet nicolas and suhas p wani science with a human face icrisat is a member of the cgiar consortium science with a human. Contour bunding agricultural engineering technique. Harold watson to improve farming methods for hilly to mountainous areas farmed in tropical to subtropical areas of the world. Contour stone bunds constructed and after 2 yrs, kadiogo, burkina faso constructed reservoir to capture runoff near makutano, kenya 1. A rectangular type, where land is bunded on three sides, with the fourth side left open to capture runoff from an elevated area and a contour type, where bunds are created in rows along the contour of a hillside. But different architects may have different approaches to this.

At present such type of big block bunds are not constructed. Design of earthen tanks welcome to provincial irrigation. This methodology was applied for identifying the suitable locations of different insitu soil and water conservation interventions such as contour bunds, semicircular bunds, small pits, contour. Sep 10, 2012 contour stone bunds are built with quarry rock or stones along the natural contour of the land to a height of 2030 cm from the ground and spaced 20 to 50 m apart depending on the inclination of the terrain. Contour bunds are constructed in relatively low rainfall areas, having an annual rainfall or less than 600 mm.

Assessment of contour bunding technology for improved. Terracing contour bunds description terracing contour bunds are ridges and ditches made of soil, dug across the slope along the contour. Contour trenches are ditches dug along a hillside in. Supplemental bunds the bunds constructed between two contour bunds to limit the horizontal spacing by its maximum extent, are nomenclatured as supplemental bunds. In particular, in us usage, it is a shallow channel with gently sloping sides.

Rainwater harvestinggroundwater rechargebunds wikiversity. Contour bunding helps in soil and water conservation. So ill try to generalise it as much as possible so that it can be applicable to all scenar. This process includes inventory and data collection of the resources that are associated with the project site. Bunds occupy a significant portion of the arable rice production area in many parts of the world. The spacing of bunds is so arranged that the flowing water is intercepted before it attains the erosive velocity. Ideally, bunds on farms should be made on the contour line.

A contour maps consists of contour lines which are imaginary lines connecting points of equal elevation. Contour bunds divide the length of the slope, reduce the volume of runoff water, and thus preventing or minimising the soil erosion. Assessment of best practises and experience in water harvesting. Design of contour bund contour bunding contour bunding is the construction of small bund across the slope of the land on a contour so that the long slope is cut into a series of small ones and each contour bund acts as a barrier to the flow of water, thus making the water to walk rather than run, at the. Regionwide, it is estimated that about 300,000 ha of land has been reclaimed. The bunds act as barriers to the flow of water and at the same time impound water to build up soil moisture storage. Changing contours indicates a change of ground form.

Site characteristic and design guidelines for selecting a site for check dams nala bunds the following conditions may be observed. Technical manual for iwmp gujarat state watershed management agency page 4 2. Effectiveness of contour bunds and gully plugs as tools for watershed treatment introduction a watershed can be defined as an area demarcated by the ridgeline separating one drainage basin from another. Every fifth contour line is made thicker for easy readability. Contour bunds are constructed in relatively low rainfall areas, having an annual rainfall or less than 600 mm, particularly in areas having light textured soils. Contour bunds divide the length of the slope, reduce the volume of runoff water, and thus preventing or minimizing the soil erosion. A swale is a shady spot, or a sunken or marshy place. Bunds play a critical role in retaining moisturewater on sloped ground, providing access to fields, and delineating ownership. In addition, when tree lines andor grass strips are also planted on the contour, they have the potential to contribute to above and below ground soil carbon sequestration. They are essentially meant for storing rainwater received during a period of 24 hours at 10 years recurrence interval.

Vertical distance is commonly known as the vertical interval or v. The stone bunds form a barrier that slows down water runoff, allowing rainwater to seep into the soil and spread more evenly over the land. Stone bunds as soil and water conservation measures in. Although the horizontal spacing is useful in determining the row arrangement. Priority has therefore been given to a range of measures for runoff and soil erosion control. Further the poor drainage properties of deep black soils gives raise to long stagnation of water against contour bunds and make it unstable. Contour bunds are also not successful in very shallow soils having a depth loss than 7. When there is rainfall, contour bund acts as a barrier to the water flow and checks the velocity. In between two contours agriculture can be practisised. Such lines are drawn on the plan of an area after establishing reduced levels of several points in the area. All water harvesting techniques contained in this guide are best.

A line drawn on a map or plan connecting points of equal elevation. In comparison to normal contour bunds, terraces even out the slope of the ground and therefore make the paddies plain. The term contour bunding used in india is same as level terraces and ridge type terraces. Design of contour bunds vertical interval between bunds v. Chapter 7 contour banks contour banks are usually designed in theory to a standard that will safely carry water resulting from a runoff event with a 10 year average recurrence interval. The type of bund contour or graded bund to be constructed depends upon the rainfall and soil condition. The purpose of this study is to present good practices in soil and water conservation and soil protection and restoration from the point of view of their contribution to reducing the vulnerability of the regions population and improving the resilience of its agrosilvopastoral systems. For the love of physics walter lewin may 16, 2011 duration.

This practice consists in making a comparatively narrowbased embankment at intervals across the slope of the land on a level that is along the contour. If the map size is large, it is written at the ends also. Assessment of best practises and experience in water. However, contour stone bunds are labour intensive and costly. Bunds may, however, serve as sources of weed propagules if poorly managed. Karamoja water harvesting field guideimplementation. Contour bunding conservation landscaping britannica. The contour lines in an area are drawn keeping difference in elevation of between two consecutive lines constant. Contour bunding or contour bundling, which involves the placement of lines of stones along the natural rises of a landscape, and contour farming. Bund is an engineering measure of soil conservation, used for creating obstruction across the path of surface runoff to reduce the velocity of flowing water.

Nomogrpahs for graded bund design in heavy soils article pdf available in journal of soil and water conservation 383. It is an important measure that conserves soil and water in arid and semiarid areas with high infiltration and permeability, and is commonly adopted on agricultural land up. They are used to prevent runoff and to conserve soil and water. Contour stone bunds for soil erosion control in the sahel. The water depths for various runoff and vertical slope is given below. Contour stone bunds are built with quarry rock or stones along the natural contour of the land to a height of 2030 cm from the ground and spaced 20 to 50 m apart depending on the inclination of the terrain. Where projects mainly strengthened existing farm bunds or promoted the construction of new farm bunds, the acceptance was much higher. The purpose of this study is to present good practices in soil and water conservation and soil protection and. The bunding design will determine the bund shape and the gradient will determine if they are bunds with fingers or bunded cells. Earthen bund this is the most popular soil conservation structure in the country and it is practiced at large scale all over india. Bunding, also called a bund wall, is a constructed retaining wall around storage where potentially polluting substances are handled, processed or stored, for the purposes of containing any unintended escape of material from that area until such time as a remedial action can be taken.

High intensity rainfall is characteristic of large areas of the sahel causing widespread rainfall runoff and erosion. Wherever contour bunds were constructed on cultivated land, they were either neglected or purposefully removed, because farmers feel that they obstruct farm operations. Contour trenches daniel sussman, bren school of environmental science and management, university of california santa barbara description. In other words a watershed is the drainage basin or catchment area of a particular stream or river, and the catchment area is that from which. Karamoja water harvesting field guide this is a field guide detailing various water harvesting methods for the purpose of irrigation, livestock, and general water stocking for nonpotable water use in the semiarid karamoja region.