Asian Journal of Water,Environment and Pollution

Lake Zige Tangco was discovered as a meromictic saline endorheic lake in central Tibetan Plateau. Its hydrochemical characteristics of water had been investigated in the summers of 1998, 1999 and 2002. The future hydrochemistry of lake water will possibly evolve into a more depleting Ca $^{2+}$ , Mg $^{2+}$ with concentrated Na $^+$ -CO $_3^-$ -SO $_4^{2-}$ -Cl $^-$ , that is to say, the lake could become a more typical salt lake.

Already available and newly collected data sets on water chemistry of twenty reservoirs located in seven river basins in Sri Lanka were analyzed to determine the status and trends in irrigation related water quality characteristics. pH of irrigation water varied within a wide range but the upper limit did not exceed the proposed level suitable for irrigation water. Salinity was found beyond the threshold level (1.250 g l $^{-1}$ ) only in two reservoirs located downstream of the Malwathu Oya basin and the electrical conductivity had never reached above 1 mS cm $^{-1}$ . Sodium absorption ratio (SAR) was well below the threshold value of 6 meq l $^{-1}$ in the study reservoirs. Least square regression model showed that electrical conductivity was a good predictor of salinity and SAR. Time series data showed no marked changes in irrigation water quality of the reservoirs located in the Mahaweli river basin over the last forty three years with respect to EC levels but the EC of those proximate reservoirs receiving additional transfer water from the trunk stream of the Mahaweli river showed a progressive decrease following the trans basin diversion.

Highland lake water management in the Great Asian Mountains is an emerging issue that needs immediate attention. This paper firstly elaborates the significant environmental services of highland lakes, in particular, the significance of water resources in those lakes. Secondly, the author analyses the challenges of water resource management in highland lakes, attributing to both global climate change and anthropogenic causes. Through the analysis of all the challenges, knowledge gaps are identified and future research activities suggested.

Promoting integrated, self-sustainable management strategies for the management of the zero-to-first- order catchments, which provide the marginal areas of every river basin, is the goal of the 'Headwater Control' movement. Headwaters provide the source of fresh water resources and changes in their characteristics may affect the water resources in all areas downstream. Because of the fractal nature of all river systems, headwaters may occupy around 50% of the land surface. Since 1989, the study of headwaters has been advanced by the 'Headwater Control Movement', later International Association for Headwater Control. After 15 years and five major international conferences, the movement has grown from a European to a global initiative, whose proceedings demonstrate a change in the approach to sustainable watershed management from 'control' to 'accommodation' and ultimately 'self-control' within the limits of the natural environment. The human dimension of headwater management remains its major challenge, especially the reform of the management institutions and the empowerment of local communities for environmental management.

This report examines the characteristics of the 'Headwater Control' philosophy in relation to three sister movements: the FAO's 'Land and Livelihood' agenda, ecohydrology, and the 'Better Land Husbandry' ideology sponsored by the World Association of Soil and Water Conservation. In September 2002, in response to the Johannesburg World Summit on Sustainable Development, the Headwater Control Movement issued its own manifesto, the 'Nairobi Headwater Declaration for the International Years of Mountains and Freshwaters' which was endorsed by five United Nations agencies and published by the United Nations University in Tokyo. Subsequently, the movement has worked towards the implementation of the recommendations of the Declaration, promoting trans-national working groups on sustainable watershed management across the Balkan States and Northern Turkey, sponsoring a NATO-Advanced Research Workshop to tackle the problem of evaluating the environmental roles of wetlands in larger headwater catchments, and initiating contributions towards embedding watershed consciousness within programmes of Education for Sustainable Development.

Abstract: The amounts of trace gases notably CO $_2$ , N $_2$ O and CH $_4$ have been increasing in the earth's atmosphere. Increased concentration of these gases leads to a warming of the Earth's surface and the lower atmosphere. The resulting changes in climate and their impacts such as sea level rise, coastal ecosystems etc, can be estimated without associating the origin of the warming to any one of these gases specifically. In this paper, an attempt has been made to review the processes involved in climate change and its effects on sea level rise and on the coastal ecosystems.

There are significant differences in the water chemistry of the Himalayan and southern peninsular rivers. Large and small rivers also show different types of water quality. Liquid and solid waste definitely contribute to water quality in urban centres such as Delhi and even coastal regions, as near Mumbai, are affected by waste discharges. The sub-continent also suffers from problems associated with floride and also arsenic in different parts. Even drinking water shows contamination with metals and POP. Thus over one billion people, both qualitatively and quantitatively, are at water risk.

Water quality studies in such aspects as POP, heavy metals and microbiology are urgently needed – particularly in regions such as Nepal and Bhutan where data base is scanty. The intensive agricultural activity in the sub- continent is reflected in enhanced levels of nutrients in various water bodies in many parts of the region. Thus, water in south Asia may be thought no longer to represent natural water quality but shows impact of different types of human activities practically in every part of the sub-continent.

Coastal belt and offshore islands of Bangladesh are vulnerable to catastrophic cyclone hazard. The broadcast media – radio and television – play a very important role to disseminate cyclone warning news bulletins to the people living in those areas, and also act to bridge the gap between the decision makers and the public. Information collected from 400 respondents at nine different areas covering the entire coastal belt suggests that peoples?ownership and access to any broadcast media has a positive relationship with their family income level. Poor people have very little access to such media news. Those living in weak/katcha (cottages and mud made) houses give great importance to media announcement. On the other hand, the frequency of experiences with previous cyclones does not show any impact on media access of those people; rather younger generation, of course with higher level of education, gives more importance to media warning signals than elderly people. It has also been attempted to study community response to cyclone shelter centres and their role to disaster mitigation. Information collected from 200 respondents at Meghna estuary suggests that the construction of cyclone shelter centres in recent years along the vulnerable coastal belt has already shown a remarkable positive result to save human lives during a catastrophic cyclone event. However, problems still remain in selecting appropriate locations for the construction of such centres, including insufficient inside space and internal mismanagement. The catastrophic cyclone of April 1991 had made a tremendous change in the human mindset and despite conservative attitudes of local people, particularly among the women, many of them are now mentally prepared to shift to cyclone shelter centres during the hazard.

Accurate estimation of groundwater recharge is extremely important for proper management of groundwater system especially in semi-arid regions. Many different approaches exist for estimating recharge. This study deals with groundwater modeling for assessing the groundwater balance and estimating the recharge in the Gundal sub-basin, which is located in a semi-arid portion of the Kabini river basin. A two-dimensional fully distributed groundwater model on the concept of predominantly lateral flow conceptualized as an unconfined aquifer has been used in this study. The modeling is supported through remote sensed data and GIS. The different modeling approaches used here gave consistent set of specific yield, transmissivity and rainfall recharge factor with the assumption of zero flow condition specified along the basin boundary. However, these parameters are found to be lower than what is usually known to occur in this geo-climatic context. The results of groundwater modeling, further supported through the groundwater chemistry analyses, show the impact of pumping resulting in regional groundwater flows influencing the hydrogeological regime in the recharge zone. The study also indicates that water levels in the excessive groundwater depletion zones in the Gundulpet area are sustained at the present level due to the inflows from the adjacent Nugu river basin.

Abstract: Chemical constituents of surface and rain water in Sri Lanka were analysed to examine the susceptibility of aquatic environment for episodic acidification. The buffer intensity of different types of surface water ranged from 8.09 ± 4.61 × 10 $^{-4}$ to 55.05 ± 21.18 × 10 $^{-4}$ moles l $^{-1}$ pH $^{-1}$ . The pH values of the rainwater samples collected island-wide once and at Kandy on a regular basis varied from 4.82 to 7.30 and from 4.46 to 6.89 respectively. About 37% of rainwater samples collected island-wide and at Kandy had pH range of 5.40–5.80. Rainwater collected from urban centres with high population densities had moderate concentrations of nitrate, sulphate and chloride ions. Although a majority of rainwater samples were within the pH defined for non-contaminated rainwater, there is a tendency towards slight acidification. If acid rain prevails, headwater streams and rivers draining the wet zone and reservoirs located at the highest elevation are more susceptible for episodic acidification.

Water samples collected from three Rift Valley Lakes (Nakuru, Elementaita and Naivasha) in Kenya in June, 2002 and one lake in southern India (Kolleru) in non-monsoon and monsoon were studied in order to understand the water chemistry of the four tropical lakes. Results indicate that Lakes Nakuru and Elementaita are highly alkaline in nature compared to Lakes Naivasha and Kolleru. Sodium is the major cation while chloride and bicarbonate are the major anions contributing almost in equal proportion (48% each). Both carbonate and silicate weathering contribute to the bicarbonate content in Lake Kolleru; however silicate weathering seems to be the major contributing factor in the bicarbonate content in the Rift Valley lakes. Fluoride content was very high in the rift valley lakes.

The water chemistry of lakes Nakuru and Elementaita strongly reflects the dominance of evaporation and crystallization mechanism. However data points for lakes Naivasha and Kolleru plot to the right of the boomerang envelope – an indication that rock weathering is not the only mechanism controlling the water chemistry of these lakes.

Results obtained indicate that if the waters were in equilibrium with minerals, the waters of lakes Naivasha and Kolleru would be in equilibrium with kaolinite while that of Nakuru and Elementaita would be in the range of albite, quartz and chlorite. The carbonate system suggests that dolomite and aragonite would be the possible minerals in equilibrium in all the lakes.

The signal reaching the satellite is mix-up of contributions from varied features on the ground surface besides atmospheric errors. Getting back the information on ground features from satellite-based data is an ill-defined inverse problem and is solved by applying statistics-based maximum likelihood (ML) type constraints. Here, the limits of classification accuracy attainable, using (in full) the professionally prepared GIS vector overlay for giving comprehensive training sets (approach 'a'), and thereafter fortifying this further even by starting with a priori probability worked out using relative fractional distribution under each class (approach 'b'), and improvement of accuracy in iterative mode were studied. Both GIS vector overlay-based approaches 'a' and 'b' gave nearly similar results for the area under different thematic classes and nearly matched with area(s) under input GIS overlay for dense, mixed and teak forest, grassland and water, and did not match for settlement, podu/blank, bamboo and semi-evergreen forests. In non-GIS based ML classification, near matching with GIS vector overlay was achieved in initial classification for dense forest, semi-evergreen forest, settlement and water. Overall accuracy and kappa coefficients were favouring GIS vector overlay-based technique giving overall accuracy in 83.5–87.5% range (and not 100%) while for non-GIS overlay approaches it was about 73%.

Statistical analyses of the glacio-morpho metric parameters show a spatial variation across Himalaya. Glacier density varies across Himalaya: it is maximum in the Sutlej and Tista basin and moderate in the Jhelum and Bhagirathi basin, while least density area is in Arunachal Pradesh basin. Most of the glaciers are simple type while some glaciers are big in size and composite in nature. The single biggest glacier contributes about 30% of the total glacier cover in the respective basins. Length and width change from west to east and consequently the elongation, relief ratio and relief area gradient. These indices suggest that the west glaciers are stream type, while eastern glaciers are patch type and occupied in high relief region.

Health of glaciers can be inferred using Accumulation Area Ratio (AAR) and the average AAR value of the Indian glaciers is 0.48; a state of negative mass balance. A comparative analysis of glaciers' AAR shows that the glaciers having zero AAR constitute about 34% of total glaciers, while glaciers having near 100 AAR constitute about 9% of total number of the glaciers. Correlation matrix between various glacio-morpho metric parameters suggests that the AAR is closely related to accumulation area, length, mean elevation and area.

The accumulation zone is gentler slope area of the glaciers and a slight shift in zero isotherms on the accumulation surface will result in quick shrinkage in accumulation area. It will further contribute to more negative mass balance and development of supraglacial and moraine dammed lake in glaciated region. Present study clearly indicates the high susceptibility of the glacier shrinking in Indian Himalaya in the present climatic change regime.

Hydrogeological investigations were carried out to obtain sufficient information on groundwater availability in the fractured metamorphic rocks in Kandy district of Sri Lanka. 47 boreholes were drilled with the average depth of 90 metres and 24 high yielding wells were selected and long term pumping tests were carried out for each well using standard methods. The calculated total of pumping rates from all wells was 8150 metric cubes per day. Pump installation depth and dynamic water levels were also calculated and the pumping time was limited for 16 hours per day allowing eight hours for recovery. These groundwater supplies have been connected to the main public water supply and no serious problems have been recorded so far since the beginning of this project. This indicates that there are many hidden groundwater sources in hard rocky areas for future. Some recommendations to maintain the wells are given here.