WATER: Quantiy and Quality
School of Environmental Sciences,
Jawaharlal Nehru University, New Delhi -110 067, INDIA
Water is essential for life on earth and is always the talk of the town either due to too much of it or too little of it. The number of rainy days varies in the Indian sub-continent from just a few days in the northwestern region (Western Rajasthan) to 365 days in some parts of Chirapunji in northeast. But there is water scarcity even at this place due to lack of suitable systems to trap the water and steep slopes that carry away water as well as the nutrients. The present annual requirement of water for our country for various users such as agriculture, domestic, industrial energy and other miscellaneous purposes is around 634 km3 and is expected to more than double within the next 50 years. This indicates that pressure on water is likely to increase in the years to come. Water derives some of the dissolved chemicals such as HCO3-, Na+, K+, Ca2+, Mg2+, SiO2, SO42-, F -and several others due to chemical interaction between soil mineral matter and also rocks below the soil. The solute load of the water determines the total dissolved solids that in turn affects the hardness of water. Key parameters such as acidity, hardness, conductivity, sodium Absorption Ratio (SAR), plant available nutrients all depends on solutes derived from the intensity of chemical interaction with the soil particles. Certain toxic elements such as mercury (Hg), Arsenic (As), Cadmium (Cd) and Chromium (Cr) also enter the water either during such reactions or due to mans input via a number of anthropogenic activities. For each such parameter, standards have been accepted either at national or international level that is found to be suitable for specific type of water use namely domestic, industrial or agricultural. A hard water containing a lot of bicarbonate, Ca and Mg is not suitable for most applications since even in industry, boilers may be corroded by hard water and in irrigation, they may affect the salt tolerance of plants and may lead to excess soil salinity.
Nature of Organic Carbon in Rivers of Kerala
V. Ittekkot1 and V. Subramanian2
1Zentrum für Marine Tropenökologie,
Center for Tropical Marine Ecology,
Fahrenheitstr 6, D-28359 Bremen, Germany.
2School of Environmental Sciences,
Jawaharlal Nehru University, New Delhi - 110 067
Kerala has an area of 26.2km2 and discharge 34.3km3 of freshwater per year into Arabian Sea with an average runoff of 1537mm. The average total suspended sediments (TSS) for the region is 25.4ppm, POC and N contents are in the range of 2-19% and 0.3-2.2% represent of TSS. POC and N content decrease with increasing TSS concentrations for the Kerala rivers. The distribution of TSS, DOC and total particulate carbon fluxes within the various Kerala rivers show that, of the total of 7.5 x 103t TSS yr-1, 0.9 x 103t DOC yr-1 and 1.5 x 103t POC yr-1 and are annually delivered to the Arabian Sea. The combined Kerala rivers show that the sediment load is 1261 x103t yr-1 with an average sediment erosion rate of 53t km2 yr-1. A rough estimate show 10 x103t organic carbon yr-1 with a denudation rate of 0.4t organic carbon km2 yr-1 either buried in the river itself or exported to the Arabian sea or degraded in the backwaters/estuaries. The degradability of riverine organic carbon depends on its residence times in the estuaries and its molecular nature. The nature of riverine organic matters in terms of its sugars and amino acids (labile constituents) and should therefore give a general picture of its degradability. In general, then, the rivers draining into tropical and subtropical seas differ from the others in the nature of their POC and DOC, whose potential for degradation in the estuaries and costal zones is much less.
Ecohydrological Investigations in the Western Ghats of India
M. P. Sujatha, S. Sankar and T. P. Thomas
Kerala Forest Research Institute, Peechi, Thrissur, Kerala
Studies quoted in this paper give a broad outline of the hydrological scenario in the Southern Western Ghats. Runoff values of 1% and less were reported from the Nilgiris irrespective of the type of vegetation while much higher values have been reported from Kerala part (20-25% of rainfall) especially after conversion of natural forests to plantations probably due to differences in rainfall. Nilgiris received hardly 1200 mm while Kerala received around 2500-4000 mm annually. Sediment yield from exploited basins were found to be higher, about four times that of protected basins. Thus it can be seen from the limited number of studies that runoff and soil erosion from forested watershed are minimum. Plantations on the other hand seem to induce erosion, especially in Kerala part of Western Ghats.
Hydrogeochemistry of Mandovi, Zuari and Kalinadi, West Coast of India
School Of Environmental Sciences,
Jawaharlal Nehru University, New Delhi, 110 067
The water chemistry of three rivers along the western coast of India were investigated during dry and wet seasons. The rivers showed a significant seasonal variations. The higher concentrations of all the major ions during the dry season was due to reduced surface runoff and due to which the sea water intrusion occurs. Chloride, sulphate, sodium and magnesium are major ions in the waters of Mandovi, Zuari and Kalinadi. During monsoon, there is heavy inputs of freshwaters which changes the complete chemistry of the rivers from brackish to freshwater. The waters of Mandovi, Zuari and Kalinadi rivers are mostly N limiting in most of the seasons.
Solute Variation in Some Minor Water Sheds, Kerala, India
K. P. Thrivikramaji and Sabu Joseph
Dept. of Geology & Dept. of Environmental Science,
University of Kerala, Kariavattom Campus 695 581
Result of a study of solute (DL) and suspended load (SL) discharge and their characteristics and transformations due to anthoropogenic action, in some of the minor (area + <2000 Km2) and adjacent rivers in southern Kerala like Vamanapuram ar., Ithykara ar., Kallada ar. And Achankovil ar. Are examined here. The load characteristics amply demonstrate consequences of a very "high degree" of human action these river basins and processes have been subjected to "Phaneomenal" changes have occurred in respect of landcover-landuse parameters due to conversion of large chunks of land into plantation (monoculture) and agricultural lands, which warrant application of chemical fertilizers, soil conditioners, fungicides and / or insecticides. Addition of organic and inorganic chemicals into the physical system resulted in considerable modification of characteristics as well as levels of DL. Estimates of sediment yield, in these minor basins, varies from 72 to 227 t Km-2Yr-1.
Water Quality of Rivers of Kerala, South Western, India
Sujit Kumar Bajpayee1 and Anuradha Verma2
1Environment Office, NHPC, Sikkim
2School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110 067
Eleven rivers of Kerala were studied for their major ion chemistry, dissolved organic carbon (DOC) in dry periods and wet period. The HCO3- concentration was found to be very low in comparison to other peninsular rivers of India in all the three sampling seasons with discharge weighted values 11.9 ppm and 0.9 ppm for monsoon and non-monsoon seasons. Discharge weighted total dissolved solid (TDS) concentration was 38.8 ppm and 3.0 ppm in monsoon and non-monsoon seasons respectively. The average values of rate of chemical and mechanical erosion in this area was found to be 142.95x103 and 108.17x103 tonnes/yr respectively with Bharathpuzha river showing highest value for rate of chemical erosion (382.83x103 tonnes/yr) and Chaliyar river showing highest value for rate of physical erosion (509.64x103 tonnes/yr). DOC concentrations ranged between 0.51 and 5.25 ppm for monsoon samples and between 2.1 and 32.6 ppm for dry season samples.
Effects of Forest Clearing on Certain Climatic Parameters Case Studies from the Catchments of the Western Ghats
P. K. Pradeep Kumar and E. J. James
Centre for Water Resources Development and Management
Calicut 673 571. Kerala, India
Forest play a major role in maintaining the climatic peculiarities needed for the ecosystem. In view of the degradation caused to the forest areas of Kerala, a study was conducted to know the influence of forest on atmospheric temperature, humidity and wind of the region. Three sets of catchments were selected for the study in the Kerala portion of the Western Ghats. Each set consisted of a dense forest, partially exploited and fully exploited catchment. The temperature values observed in dense forest catchments are always lesser than the exploited ones. The relative humidity in the dense forest catchment is more than that of exploited catchments. The wind speed at 2 metres height goes up with increased deforestation.
Impact of Plantation Activities on Soil Properties in the Western Ghat Region of Kerala
Division of Soil Science, Kerala Forest Research Institute,
Peechi 680 653, Kerala
This study was carried out in the Kerala part of Western Ghat to evaluate the impact of plantation activities of teak and eucalypt, the two most important species planted in more than 95,000 ha in Kerala on soil properties in relation to adjacent natural forest, South Indian Moist Deciduous type. The study revealed that soil texture varied from loam in the natural forest to sandy loam in plantations. Soils in the natural forest were medium acidic while those in the plantations were slightly acidic. Plantation soils had higher contents of gravel, sand and bulk density and lower silt, water holding capacity, pore space, volume expansion, organic carbon and cation exchange capacity. The total as well as different forms of N and P were also lower in the plantations.