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Announcement Executive Committee Limgis 2001 Lake2002
RESEARCH ARTICLES
Aquatic ecosystem conservation via watershed approaches
Ahalya N and T.V. Ramachandra
Aquatic ecosystems' vital functions such as recycling of nutrients, purification of water, recharge of ground water, augmenting and maintenance of stream flow, and habitat provision for a wide variety of flora and fauna, along with recreation for people necessitates their sustainable management through appropriate conservation mechanisms. Failure to restore these ecosystems will result in sharp increase in environmental costs, extinction of species or ecosystem types, and permanent ecological damage.
The burgeoning population accompanied by unplanned development has led to the pollution of surface waters by residential, agricultural, commercial and industrial wastes / effluents and decline in the number of
waterbodies. Increased demands for drainage of wetlands have been accommodated by
channelisation, resulting in further loss of stream habitat, which has led to aquatic organisms becoming extinct or imperilled in increasing numbers and to the impairment of many beneficial uses of water, including drinking, swimming and fishing. Various anthropogenic activities have altered the physical, chemical and biological processes within aquatic ecosystems. An integrated and accelerated effort with holistic approach involving the entire watershed is necessary towards environmental restoration and preservation to stop further degradation of these fragile ecosystems. Soil and water conservation is a very important aspect of watershed management. But, other aspects such as type of plants (species selection based on local requirement and environment) and socio-economic features should be given due importance in order to realize the highest benefits for the inhabitants.
In recent times, watershed deterioration has taken place due to uncontrolled, unplanned and unscientific land use. Agriculture, mainly cultivation on sloping land without adequate precautions and over cropping, deforestation, excessive grazing, shifting cultivation; unscientific mining and quarrying; non-cooperation of the people, etc., are some of the factors affecting watersheds.
The consequences of the above unsustainable practices can be as follows:
(i) Low productivity of land with respect to food, fuel, forage, fibre and fruits, (ii) Erosion and denudation within and outside the watershed, (iii) Siltation of reservoirs, lakes, etc., (iv) Frequent floods and droughts and (v) Poor health of people and cattle.
Watershed affects people in every sphere of life. The sustained production of food, fuel, forage, fibre and fruits by the management of vital resources of water, soil and vegetation and phenomena like floods and droughts is determined by the watershed functions. Each individual watershed has a number of distinct characteristics, which affect its functioning with respect to receiving and disposing water. The eight watershed characteristics important for its functioning are - physiography (size, shape, drainage pattern, etc.), soils and geology, land use, vegetative cover, precipitation, run-off rates, socio-economic factors (demographic and sociological features, land tenure structure, attitudes and behaviour of inhabitants, etc.) and organisation (stakeholders' participation).
Sustainability can be achieved by designing programmes to maintain the synergistic relationship between land and water cycle, raise productivity of available land, and restore, reclaim and rehabilitate the degraded land. Till date, all resource protection programmes have historically focused on single goals or a small set of goals. These programmes have succeeded in identifying and controlling, to some degree, the larger point sources of pollution. It is time now to use an approach that addresses the interconnections between water resources and the land and air surrounding the resources. The watershed approach thus includes not only the water resource, but also the surrounding land from which the water drains.
Conservation of aquatic ecosystems should aim at containing the deterioration of natural resources i.e., conservation of soil and water, maintaining the ecological balance for sustainable farming systems and economic development of the area by simple and indigenous methods, etc. Major features of these conservation approaches are: targeting priority problems, promoting a high level of stakeholder involvement, integrated solutions that make use of the expertise and authority of multiple agencies, and measuring success through monitoring and other data gathering activities. In addition, it is necessary to educate citizens and convene a wide range of stakeholders including industry, environmental groups, citizens, and other local governments to address local and regional water issues. This holistic approach helps in enhancement in the productivity of all components of watershed, be they croplands, grazing lands, water systems, etc.
The development programme, in order to espouse integrated approaches with systematic planning at micro (may be at village) and macro (river-basin) levels, requires appropriate incentives for promoting soil and water conservation, water-use efficiency, participatory planning and management of the various stakeholders, cost sharing for watershed treatment among the various stakeholders, linking up the community through resource sharing and cross subsidization (achieved by using the strategic importance of water and water harvesting structures), developing market linkages, i.e., creating a market for water conservation and agronomic practices like farm ponds, composts,
biofertilisers, seed-banks, etc. Thus, the planning and development of watersheds lead to protection of the ecosystem and results in immediate gains for the people. Such programmes benefit the weaker sections of the society who live in these areas and the watershed is an ideal unit for phased agricultural development.
Thus, watershed management is the rational utilization of land and water resources for the optimum production with minimum hazard to natural resources. It essentially relates to soil and water conservation in the watershed which means proper land use, protecting land against all forms of deterioration, maintaining soil fertility, conserving water for farm use, proper management of local water for drainage, flood protection and sediment reduction and increasing productivity from all land uses.
· Pollution abatement practices might be applied to reduce the generation of non-point source of pollution (mainly agricultural and storm runoff) through source reduction, waste minimisation and process control.
· Compensatory afforestation with native species in barren areas to control the entry of silt from run off. There is degradation in vegetation cover due to unsustainable land use practices.
· Infiltration trenches would be useful in reducing the storm water sediment loads to downstream areas by temporarily storing the runoff.
· Extended detention dry basins are to be provided in removing pollutants primarily through the settling of suspended solids.
· Constructed wetlands are recommended for the purpose of storm water management and pollutant removal from the surface water flows.
· On soils with a tendency to crust, management options include:
planting seeds at shallow depths, protecting the soil surface with mulch or crop residues,
maintaining a rough soil surface by not over-tilling seed-beds, keeping the soil surface moist until seedlings emerge,
mechanically breaking crusts that form, selecting crops that are able to exert pressure during emergence,
planting two to four seeds together to increase the pressure they exert during germination, and
using transplants rather than seeds.
· Management practices for soils subject to pressure pan formation include reducing or eliminating disk harrowing, using a chisel plow or subsoiler to break tillage pans that have already formed, and limiting vehicle traffic to the smallest possible area of the field.
· Rotation of crops rather than monoculture to reduce the need for N and assist with pest control and help in aeration of soil.
· Promoting public education programs regarding proper use and disposal of agricultural hazardous waste materials.
Watershed Development programmes (WDP) designed taking all the above factors will show a clear hierarchy of benefits and beneficiaries as witnessed by successful programmes in villages of Ananthpur district (Andhra
Pradesh), and Rajkot, Surendranagar, Amreli, Bharuch and Panchmahal districts of Gujarat. The success of the WDP's was mainly due to unprecedented devolution of decision-making power backed up by financial allocation directly to the district level and hence to the village organisation level, creation of partnerships between government and non-government
organisations, and technical and financial feasibility. The project placed special emphasis on "improving the economic and social conditions of the resource poor and the disadvantaged sections of the watershed community". In most successful
WDP's, success was mainly achieved through equitable distribution of benefits from land and water resources, and also through greater access to income-generating opportunities.