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In this article we will discuss about:- 1. Components of Watershed Management 2. Watershed Management Practices 3. Evolution of Watershed Development Programmes.
Components of Watershed Management:
i. Land Management:
The land management refers to keep all those properties of land in proper order, which likely to affect the soil yield potency. The land characteristics such as terrain, slope, formation, depth, texture, moisture, in-filtration rate and soil capability are the main to consider under land management activities for watershed development.
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In broad sense the land management interventions includes following activities:
a. Vegetative measures
b. Structural measures
c. Production measures; and
d. Protection measures.
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The vegetative measures are the primary land management measures. The development of grass lands/pasture lands for erosion/soil loss control; adoption of contour farming and strip cropping practices on hill faces; growing of vegetations on barren lands or simply keeping the land under vegetations are the common practices used under vegetative measures for land management.
These measures are very effective to check the soil erosion, along with less cost expensive and easily practicable for the farmers. The practices such as development of vegetative cover, plant cover, mulching, vegetative hedges, grassland management, agro- forestry etc., are also included under this kind of measures.
The structural measures (mechanical conservation measures) such as bunding, terracing, check dams etc., are used at the steep lands for controlling the soil loss, especially when vegetative measures are ineffective. These measures are not so common as the vegetative measures because of involvement of heavy expenditure of money.
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Similarly, the spurs and gabions used for stream bank erosion control; the gully plugging structures like drop structures, spillways etc., used for gully control; and farm ponds used for safe water storage in the farmland area, are also considered as mechanical measures for land management.
These structures offer their immediate effect on soil erosion/soil loss check, but very cost expensive, requires proper site selection, design and construction. Because of this reason, their construction is not possible by the farmers; the government normally executes it.
The production measures for land management include the practices such as mixed cropping, strip cropping, cover cropping, crop rotations, cultivation of shrubs and herbs, contour cultivation, conservation tillage, land leveling, use of improved variety seeds, horticultural practices etc. The objective of these measures is to enhance the production potential of the land either by conserving the soil or enriching the nutrient status.
The protective measures are the landslide control structures, gully plugging structures, runoff collection structures etc. Adoption of these measures depends very much on the land characteristics.
ii. Water Management under Watershed Management:
Under watershed management task the water management is one of the very important components. A good water potential in watershed provides a conducive path for its overall development. In watershed the main source of water is the rainfall; however, the incoming ground water from surrounding areas also shares to some extent. A large portion of rainwater is lost either due to flowing away (runoff) from the area or by some other means.
In order to manage the rainwater, it is very essential to check the out flowing rain water. It could be done by constructing the structures like pond, reservoirs etc. in the area. Also, the rain dependent farming systems can be practiced for better utilization of rainwater is also considered as a measure for water management. Apart from conserving the rainwater, their judicious use either for crop production or other farm operations, also play very significant role in water management.
As for as the water management regarding irrigation point of view is concerned, the selection of most suitable irrigation method depending on the crop, soil, land topography, availability of water in the area etc., is very important. Those irrigation methods should always be at priority, which have better water use efficiency, lesser loss of water etc. Similarly, the choice on cropping system, crop variety, and crop duration etc., based on the water availability can also be very effective in water management.
Overall, various interventions followed for water management are outlined below:
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a. Rainwater harvesting.
b. Ground water recharge.
c. Maintenance of water balance.
d. Preventing water pollution.
e. Economic use of water.
In watershed the water conservation by rainwater harvesting is most significant as compared to the other means. The harvested rainwater can be retained for the duration of its need by designing and constructing the suitable structures in light of the same.
The rainwater harvesting can be in the form of profile water conservation or surface water storage. The water conserved in the topsoil profile is the profile water conservation. Using the practices of tillage operations such as conservation tillage, zero tillage, mulch tillage etc. it can be achieved.
Depending on the moisture content in the topsoil profile a suitable crop can be taken successfully. Also, if the quantum of rainwater is very high then a part of that gets percolate to the lower soil profile and joins to the water table. This happening is called ground water recharge. There have been formulated several water harvesting techniques, worldwide.
However, few simple and cost effective rainwater-harvesting structures are listed as under:
a. Percolation pits/tanks
b. Farm ponds
c. Bunds and terraces
d. Reservoirs
e. Community tanks, and
f. Water spreading.
iii. Biomass Management:
In a watershed the task of biomass management can be achieved by following intervention areas:
a. Eco-preservation
b. Biomass regeneration
c. Forest management and conservation
d. Plant protection and development of social forestry
e. Increasing productivity of animals
f. Income and employment generation activities
g. Coordination of health and sanitation programmes
h. Better standard of living of people
i. Eco-friendly life style of people, and
j. Formation of learning community.
Watershed Management Practices:
A watershed may involve a host of problems related to soil, water, society etc., and constraints in between. To remove all the associated problems mere should be need-based objectives. For achieving the target, various practices need to follow in the watershed.
Amongst them the most common practices are listed as under:
1. Management purpose
2. Increasing infiltration rate
3. Increasing water holding capacity of soil
4. Preventing soil erosion, and
5. Method and accomplishment.
The practices to be used for watershed management should be decided on the basis of the management objectives, exactly. Otherwise, the expected result may not be possible to get achieve. For example – if there is need of enhancing the ground water potential in the watershed then priority must be given for those practices, which augment the ground water recharge, effectively. A little deflection in selection of practices may cause in-conducive result.
The task of increasing infiltration rate is to enhance the soil moisture status; and accordingly to grow the crop depending on available soil moisture. On the other hand, the enhancement in infiltration rate causes reduction in level of runoff yield from the watershed, which in turn to affect the net available water for reservoir storage or satisfying the demand of other’s need. The practices to enhance the infiltration rate are the tillage practices, cropping system, addition of organic materials etc.
The tillage practices make the topsoil surface in loose condition as result when rainfall takes place then a large amount of that gets enter the soil. The crops enhance the infiltration rate in significant way. In cropped field there is development of surface roughness, which obstruct the overland flow. Because of this reason the rainwater gets more time to retain over the land surface, as result a huge amount of water gets infiltrate into the soil. The organic matter in the soil improves the soil texture, favorable to enhance the infiltration rate.
The status of water holding capacity of the soil falling in the watershed plays very important role to develop overall effects on watershed behavior, either that is in respect of increasing the runoff amount, soil erosion/soil loss or making the soil properties better for good crop yield. The water holding capacity of soil can be improved by adding organic matters in the soil.
The management of watershed with severe soil erosion problem requires very attentive measures to check the erosion, immediately. The practices to be used for erosion control depends very much on the erosion intensity, soil features, cropping practices, mainly. If erosion intensity is not very high and land slope is in mild range then agronomical measures could be significant to check the soil erosion. On the other hand, when erosion rate and slope steepness of the area is very high then agronomical measures are not effective to check the erosion.
For this situation, the mechanical measures such as bunding, terracing etc., are very effective to check the soil erosion. Similarly, for gully erosion control a host of practices/methods have been devised such as drop structures, check dams, gabions etc., can be suitably used for watershed management.
In watershed, if there is stream bank erosion problem, then it can be tackled by using various methods such as spurs, gabions and agronomical measures depending on the bank situation and stream flow rate. The suitable measures for erosion control have been enlisted in Table 27.10.
The watershed management measures can be grouped under following two main categories:
1. In terms of purpose; and
2. Method and accomplishment.
In first category of management measures, the land use and treatment measures are considered which are effective to increase the infiltration rate and water holding capacity of the soil and also prevent the soil erosion from watershed. Under this group, all the biological and mechanical methods employed for erosion control, are included.
In second category those measures are included, which are planned primarily for the management of water flow. The flood water retarding structures, stream/channel improvement to make their carrying capacity sufficient, minor flood-ways, sediment detention in watershed etc., are counted for watershed management work.
In brief, the various control measures adopted for watershed management work are listed as under:
1. Vegetative Measures (Agronomical Practices):
(i) Strip cropping
(ii) Pasture farming
(iii) Fertilizing the crop land, and
(iv) Grass land farming etc.
2. Engineering Measures (Structural Practices):
(i) Gully pluging
(ii) Diversions
(iii) Water ponds
(iv) Reservoirs
(v) Drainage works
(vi) Flood protection
(vii) Ground water recharging structures, and
(viii) Terracing, bunding etc.
The use of above measures or structures in proper co-ordination always proves better performance. The difference between above two categories of measures is mentioned in Table 27.11.
Evolution of Watershed Development Programmes:
The evolution of any technology or development programmes depends on the problems, which may be of any from. To remove the problem there should be positive effort by the concerns. But few problems are such in nature and in shape, which are not possible to remove by an individual/community/unit.
For example – the non-availability of water in the area cannot be solved by a specific person, but there is need of mass of people or involvement of government. In such crucial condition, the government comes in front to tackle the problem. For which various suitable projects/programmes are formulated at state level or national level by the government.
In this aspect, the Drought Prone Area Programme (DPAP) project, which objective is to combat the frequent recurrence of drought in the states, was formulated during the year 1975 as a Centrally Sponsored Scheme, with state share of 50:50. The DPAP was adopted on the watershed approach in 1987. The DPAP is concentrated on non-arable lands.
The main components of DPAP are as below:
i. In-situ soil-moisture conservation.
ii. Agro-forestry.
iii. Pasture development.
iv. Horticulture and alternate land use.
The programme entitled “Integrated Wasteland Development Programme (IWDP)” was introduced in the year 1992, in which there is provision of 100% central assistance. Through this programme the afforestation and soil & moisture conservation measures were undertaken in wastelands under government, community or private controls. In Andhra Pradesh the programmes on dry land development with the introduction of new watershed guidelines prepared on the basis of Rao’s Committee Report, have developed a massive change (1995-96).
The new guidelines of watershed management introduced the integrated approach and participation of village communities; by these features there is good effect on overall development activities. In later years, all the area development programmes either they are DPAP, IWDP or Desert Development Programme (DDP) programmes were implemented under new guidelines.
In the year 1998 a new term called ‘watershed-plus’ was introduced to adopt new approaches in watershed management projects. The special feature of this project is to give opportunity to those people and women who have no land; and also to the poorest people.
The Hariyali guidelines was issued in the year 2003-04 is also a kind of evolution in watershed management programmes. Under these guidelines the programme implementation of watersheds is carried out through Gram Panchayats. The Gram Panchayats have been given full responsibility for implementation of watershed programmes.