FOREST RESOURCES About 20 per cent of land area is

covered with forests, that is around 60 million hectares in India and 6 million hectares in Andhra Pradesh. It comes to 0.08 hectare per capita in India whereas the world's average is 0.64 hectare per head. Temperature and rainfall (moisture content) are two important parameters which decide the nature of forests at a place. (Table 2.1)

Dense and diverse forests grow near the equatorial latitudes. In other zones, the nature of forest depends upon the extent of rainfall, soil fertility, climate and seasons. Conifers and temperate forests are seen in North America and Eurasia. Tropical rain forests are available at some parts of Central America, Australia, Indonesia and temperate shrubs at mediterian area. Tropical seasonal forests are grown at

places in South central parts of America, South eastern parts of Asia, India and deserts in North Africa (Sahara) and Mexico.

These forests grow at different places on different latitudes and altitudes (Figure 2.2) from equator to poles. In tropical coastal areas, near estuaries where salt water or fresh water is in abundance and nutrients are available in plenty, most productive mangrove forests grow. Forests are responsible for maintaining the ecological balance and biogeochemical cycles in nature.

FIGURE 2.2 Distribution of forests. Functions of a forest are listed below: (i)Soil erosion, floods and droughts

can be prevented,

(ii)CO2 is utilized and Oz is released into the atmosphere,

(iii)Heat balance on earth is maintained by absorbing solar radiation and greenhouse gases,

(iv)Coastline is protected,

(v)Pulp, resin, fibre, gum, honey, medicine and other valuable products are obtained,

(vi)Forests are the main source of timber and fuel wood,

(vii)They provide the habitat for wild life and preserve biodiversity,

(viii)They are the source for knowledge, recreation and tourism, and

(ix)Forests are developed for economical gains.

Inspite of a number of advantages, 2 per cent forest area is removed every year. Some causes of deforestation are as follows:

(i)Increase in population numbers, their needs and life styles

(ii)Urbanization and industrialization (iii)Mineral exploration

(iv)Construction of dams and reservoirs which submerge forest lands

use, agricultural operations and illegal trade activities

(vi)Overgrazing

Demerits of Deforestation

(i)It leads to change in the climate. As rainfall reduces and temperature increases, desertification starts.

(ii)It leads to loss of food products, useful material and livelihood.

(iii)It causes loss of biodiversity and imbalance in ecosystem.

(iv)It leads to global warming.

protecting and improving the forest lands for the overall benefits of humanity. People should understand cutting one tree (more than 10 years old) will never be equal to planting 50 seeds now.

Wild Life Protection Act (1972) and Forest Act (1980) positively help to preserve forests and wild life. One should balance short term and long term gains and the regeneration capacity of new plants and the removal rate of aged plants. Social forestry or afforestation programmes are involved in the intensive plantation schemes for

sustainability. The desirable goals are to prevent commercial exploitation, to grow different categories of plants and to conserve plant growth in parks and sanctuaries, to reclaim waste lands and monitor all forest welfare programmes. 2.6 WATER RESOURCES

Hydrological Cycle

Water is the most essential commodity for all living beings for their survival and development. It is required for various domestic and industrial needs, irrigation and power supply, navigation,

recreation and aquatic life. Uneven distribution (place and time) of rainfall leads to floods and droughts at some places. Increase in population and their standards of living are mainly

responsible for depletion and pollution of water bodies. Serious problems are occurring due to the non availability of adequate supply of quality water sources in the country. Conservation, purification and recycling are the main options for obtaining continuous supply of water.

Hydrology is concerned with the transportation of water limited to the

release of water from clouds or precipitation and re-entrainment of water into clouds through evaporation from different water surfaces (Figure 2.3). About 20 per cent of rain falls on the land surface and flows as run off, as the major portion of the earth is covered by sea. Out of this, only 22 per cent reaches the surface sources such as rivers, lakes; 10 per cent percolates into the ground; 25 per cent is retained as soil moisture in the top soil and the rest is evapotranspired from land, water and other surfaces. Surface run off depends

upon the characteristics of the catchment area, such as topography, ground slope, soil characteristics, ground water table, land use patterns. A substantial portion of the rain water is getting infiltrated into the ground and gets further percolated into deeper layers for storage. Movement of ground water is very slow. Water that is held in the top layers of the soil under capillary forces is known as subsurface water which is very important for crops.

FIGURE 2.3 Hydrological cycle. Out of 170 million hectare metres of annual surface flow, 80 per cent portion joins the sea. Total annual discharge in

major rivers like Brahmaputra or Ganges exceeds 5 x 106 cubic metres of flow and Mahanadi, Godavari or Krishna may have an annual run off of less than 1 x 106 cubic metres.

In India, length of important rivers and main canals is around 10 lakh kilometres. Lakes and resources are about 3 million hectares of surface area. The ground water storage appears to be to an extent of 40 million hectare metres, but only a small fraction of water is available for use.

below ground level. Water can be pumped from shallow or deep wells. Heavy discharges from deep ground layers raise in pumping costs, change the soil characteristics, affect the climate, increase the dissolved salt contents (like fluorides) in water and may also cause favourable condition for landslides or earthquakes.

Diversion of water from lakes and silting of reservoirs may also alter the landscape.

Water is used for irrigation, domestic, industrial needs and also to generate

electricity. Irrigation needs 5,000 to 15,000 m3/hectare depending upon the crop variety and domestic consumption is 150-300 litres per capita per day based on the standards of living. Major portion of water (about 70 per cent) is used for irrigation purpose, 15 per cent is used for power generation and only 5 per cent is consumed in the domestic sector. Some parts of Punjab and Tamilnadu utilize more than 75 per cent of ground water sources. All these numerical values of rainfall, run off or ground water resources are average

figures only.

People experience floods at some places during monsoon months whereas some are continuously drought prone areas. In reality, availability of water is location specific and sometimes seasonal. However the total quantity of water present in the environment is a finite and fixed quantity. Only a small fraction of that quantity is available for utilization in different sectors. Similarly, small percentage of available water resources takes part in the hydrological cycle. The major share of water storage

that cannot be directly utilized, also contributes to the ecological balance on the earth and so is an asset. Another significant point of interest is that water flows do not observe physical or geographical boundaries such as neighbouring districts, states or countries. Floods or pollution at one place may affect people over one hundred kilometres on the downstream side.

River Valley Projects

portion of river flows essentially meant for storage of water during flow season (monsoons) or floods and supply the all time needs to meet the agricultural demands for raising different types of crops through a network of canals. They are also useful for generating electricity, supplying drinking water, raising fish culture, navigation and recreational purposes.

The component structures of a river valley project as shown in Figure 2.4 are as follows:

water as a reservoir

(ii)Supply sluice-to regulate the supply of stored water to the different needs through canal network

(iii)Spillways-to safely dispose the flood water or excess flows into the river so that no damage is done to these structures

(iv)Canals-to convey water to far off places for meeting the water requirements

The highest water level up to which water can be stored is known as full reservoir level. Water coming into the

reservoir above this level has to be disposed off with the help of a surplus weir or spillway. Water stored above the sill level of the supply sluice is released into the canals.

Water storage improves greenery and also changes the climatic conditions of the surrounding environment. Waterlogging and salinity affects soil fertility. Water storage leads to mosquito breeding. Large dams are supposed to create earthquakes in the nearby regions and submerge more areas.

Floods and Droughts

(i)Due to intense rainfall or melting of snow, rivers get filled up with water and overflow breaches canals or tanks, submerged lands and destroys

life and property. Floods also cause soil erosion and change the land use patterns. Flood flows can be estimated, flood timings can be predicted and loss of life can be prevented to some extent by adopting water resource management systems. Forests regulate water run off, reduce soil erosion, retain soil moisture and thus help in controlling floods.

(ii)Drought is lack or insufficiency of rain (less than 400 mm/year) for an extended period that causes water

shortage, depletion of ground water levels and soil moisture, reduction in stream flows and creates hydrological imbalances. It is the most serious hazard to agricultural production in all parts of the world. It leads to serious economic consequences and untold human misery. Water is not available even to satisfy basic human needs in such areas. Some areas are highly drought prone in the country.

Cloud seeding for rains is quite expensive and unpredictable. The better

alternative appears to be to conserve resources, use carefully and recycle water after proper treatment. Another effective method is to resort to watershed management practices.

Priorities and policies may be framed to link river waters depending upon the feasibility and conserve ground water adequately so that both flood and drought situations are prevented.

Watershed Management Practices Watershed is the area, draining the precipitation and a synonym for a

catchment of a river basin. The

important characteristics of watershed are the size, shape, type of drainage and the distribution of rainfall. Some other considerations are degree of ground slope, land use pattern, vegetation, geology of rock strata and soil characteristics and meteorological factors.

Watershed management is a concept of developing a technology to use every drop of rain water at the place of occurrence. It can be location specific as per the needs like social forestry, soil

conservation, crop management or ground water storage. An integrated approach for the watershed management should include protecting natural resources for attaining the desired results.

The following steps are involved: (i)Data collection with details of

hydrology, drainage and topographical features of an area over a good length of time

(ii)Data analysis and planning for the measures to be adopted for:

(b)Ground water recharge such as construction of check dams, percolation tanks and rain water harvesting measures

(c)Improvement of drainage and utilization of surface storage

(iii)Working out and tallying the water balance in the watershed by measuring evapotranspiration, precipitation, run off, recharge to ground water, valley storage, irrigation, ground water draft, infiltration and out flow

construction of structures, encouraging social forestry, artificial recharge, spacing of wells and drip or sprinkler system of irrigation

Deforestation should be avoided. Open drains are to be improved in plains. Conjunctive use of surface and ground water prevents water logging. Proper drainage and ground water pumping is necessary to preserve water quality and maintaining crop yield.

Water or moisture content should be preserved in top soil to keep the nutrients safely in porous soils. Soil

conservation and vegetation cover, improves the ability of land to hold water. 10 mm rainfall in a small farmer's land about a hectare, amounts to 100,000 litres of water, if stored through water harvesting programmes.

Soil conservation measures include contour bunding, ploughing, (at right angles to hill slope), fallowing (no crops), trenching, terracing (series of steps) and soil reclamation. The objectives of water harvesting are to conserve rain water, to recharge ground water source and to increase agricultural

productivity. On sloping grounds or plains, vegetation reduces run off. Contour bunds, trenches, vegetative barriers prevent land slides on mountain slopes. Desilting of existing tanks on a regular basis is the simple and best method of improving water storage capacity.

Water harvesting recharge pits can be constructed in court yards in individual houses to collect rain water from roof tops. Small bunds may be constructed to prevent the movement of rain water to the adjoining fields.

While considering the water conservation measures in a particular area, it is necessary to make liberal provision for the downstream interests and the riparian rights. If a number of watersheds on the upstream side adopt conservation, storage and recharge measures are taken, the irrigation or water supply tanks or storage structures on the downstream will suffer. It is not possible or advisable to utilize the entire water of a river basin without serving the interests of the downstream areas. Is it possible to control floods without

releasing water from river to downstream regions? That is why water resources belong to the entire humanity. Ecological crisis can be prevented by the justified equitable distribution of natural resources in any democratic set up.