Extreme Events and Headwater Management: Reflections on the Magnitude-Frequency Issue
Martin J. Haigh and Jon Hellin
Oxford Brookes University, Oxford, UK.
The impact of extreme events, not least landslides, on hydrological systems may be proportionately greater than everyday events, even when their magnitude is scaled by their recurrence interval. Case studies from the Himalayas and central America demonstrate that landslide sediment yields from extreme events far exceed those due, in the first instance to the normal run of landslides and in the second instance to sediment generation by even agriculturally accelerated soil erosion. Neglecting the role of such impacts, merely because they do no operate according to normal human time scales, represents a potentially dangerous underestimation of watershed process dynamics.
Sedimentation and Shrinkage of Dal Lake – Kashmir
T. A. Kanth and G. M. Rather
Dept. of Geography & Regional Development,
University of Kashmir, Srinagar
The increase in man’s interference in ecological balance beyond tolerance limit, impares the ecosystem and leads to hazardous problems. Dal lake as such has been deteriorated so badly that it exists in a critical state of balance and any further change will lead to a serious situation. The present paper is an attempt to investigate shrinkage of Dal Lake as a result of Sedimentation. An assessment of the time required for the complete disappearance of the Lake has been made on the basis of rate of shrinkage. The study is an attempt not only to investigate the causes of the lake shrinkage but also suggests some remedial measures.
Restoration of Riverine Ecosystem: A Case Study in the Upper Brahamaputra Basin
Sanchita Boruah and S. P. Biswas
Department of Life Sciences, Dibrugarh University, Assam: 786 004
The Brahmaputra River system, one of the largest in the world, is blessed with a variety of aquatic fauna. The ichthyofauna alone comprises nearly 200 species, many of them are highly esteemed as food while over 50 species are considered equally lucrative for their aesthetic value. However, the river dolphin (Platanista gangetica) is undoubtedly the most fascinating fauna of the Brahmaputra. The species is very sensitive to water quality and are found in groups where there is congregation of fish. Till 70’s the dolphin was abundant throughout the river. Wanton killing and habitat degradation are said to be the major factors of depletion of dolphin and other megafauna. Shrinkage of fish spawning grounds especially the destruction of flood plain lakes is a matter of great concern. The present communication deals with the present status of riverine fauna of the upper stretches of the Brahmaputra system and also an ecohydrological approach has been made for restoration of the aquatic habitat.
Ecohydrology and Biogeochemistry of the Himalayan Lakes: A case study
Brijraj K. Das
Centre of Advanced study in Geology,
Panjab University, Chandigarh-l600l4 (India)
The Himalayan fresh water lakes show varying chemistry in terms of solutes, bio-geochemistry, mineralogy vis-à-vis ecohydrology of the water body. These are primarily related to enormous altitude variation governing the climate, vegetation, agriculture, lithology, tectonics and type and intensity of erosion/ weathering at source. The Renuka Wetland and Parashram Tal in Lesser Himalaya have shown that in a intensely crumpled carbonate and silicate lithology at the catchment, the water and sediment chemistry are dominated by carbonate weathering. The CIA value being higher in the water body sediment (79) than the average shale value (70-75) and rate of sedimentation 3.3 mm/yr indicate moderate to high weathering in the catchment. The abondance of illite and its crystallinity reflect wet and warm climate. The increasing trend of CaCO3 down core and its high concentration in sediment grab samples from the water body suggests its precipitation in fresh water due to consumption/escape of CO2. The decreasing trend of major and trace elements in the core samples elucidate dilution effect of CaCO3 and grain size control. The higher concentration of both major and trace elements in wetland grab samples and depletion in samples from water body further indicate dilution effect and grain fractionation in case of the latter. The anthropogenic in put is evident in Parshram Tal clearly, although the Renuka Lake also receives run off from the hills and agricultural land. The C/N ratio and depleting tendency of organic carbon and nitrogen down core are consistent with the increasing trend of inorganic CaCO3 suggesting adsorption of organic carbon by the latter and its derivation from non-vescular aquatic source. At shallow levels mixture of terrestrial and aquatic source is indicated.
Chemical Composition of the Rainwater in High Altitude Himalayan Ecosystem, Garhwal Himalaya, India
Sarfaraz Ahmad and Syed Iqbal Hasnain
Glacier Research Group, Jawaharlal Nehru University,
New Delhi- India
About 60-80% of water input in high altitude Garhwal ecosystem comes through monsoonal precipitation and control the hydrology and hydrochemistry in the region and downstream. However the chemical and physical characteristics of the monsoonal precipitation at high altitude are not well understood due to poor logistics and rugged terrain. For studying the chemical characteristics of perception in high altitude the rainwater samples were collected at 3800 msl in Central Himalaya for the Indian monsoon period (1 July - 30 September 2000). EC (Electrical Conductivity), pH and concentration of the major ions Ca+2, Mg+2, Na+, HCO3-, SO4-2, NO3- and Cl- were determined. Monsoonal precipitation was extremely dilute and the average electrical conductivity was 6.0 mS/cm. The average pH was 5.5; it is just equilibrate to clean atmosphere. 50% of the samples had pH ranging from 6 to 6.3 as mild alkaline, however 6% of the samples were in ranging from 4.6 to 5.5 on acidic site. Most dominant ions were Ca+2, NO3 - and the concentration of acid forming anions such as NO3- and SO4-2 were higher than the concentration expected in remote area. It may be related to long range transport from Indian subcontinent. Seasonal variation in rainwater chemistry is also significant as high Electrical Conductivity and high concentration for the most ions in July and lower concentration in August and September respectively. Concentration / volume ratios of ions were low in the July, August and increases in September suggest frequent wet deposition results in strong scavenging in high altitude ecosystem.
Ecohydrological Characters of Some Key Aquatic Ecosystems of Northeast India: Sediment Size Distribution, Mineralogy and Environmental Geochemistry
Civil Engineering Department,
Indian Institute of Technology - Guwahati,
The ecohydrological quality of the floodplain wetlands of the Brahmaputra basin is poorly known. To gain an understanding, water and bottom sediment samples collected from ten north bank wetlands were analysed for their elemental chemistry, grain size distribution and mineralogy. The seasonal and spatial distribution of major elements over these wetlands (spread from upstream to downstream) was evaluated. Most natural wetlands of the Brahmaputra valley indicated high DO levels except a few wetlands receiving BOD loading from urban sewage, where DO levels were found to be 1 to 2 ppm. Water chemistry of the samples collected from different wetlands indicated predominant influence of natural inputs with the following concentrations: Organic matter content: 8 % - 15%, Organic Carbon 5% - 9%, pH: 7.1 - 7.8, Conductivity: 220-340 µS/cm, Total N: 1.4 - 3.6 ppm, Dissolved P: 0.2 - 0.4 ppm, SiO2: 4-11 ppm, Na: 5 - 24 ppm, K: I - 6 ppm, Ca: 16 - 68 ppm, Mg: 13 - 23 ppm, Cl: 5 -24 ppm, SO4: 8 - 15 ppm. Mean concentrations of the trace metals in the soils were measured as (all in µg/g except Fe in percent) Fe: 5, Mn: 630, Zn: 104, Ni: 86, Cr: 62, Cu: 86, Pb: 44. Wetland sediments varied in size from fine sand to clay and were found to be richer in clays (mostly chlorite, illite, kaolinite) exhibiting high adsorption potential. Hydrogeochemistry revealed difference between elemental concentrations in the wetlands and those of the main river with respect to TOM, TOC, TN and most of the trace metals studied. Influence of ground water base flow and wetland dynamics were considered to be two major factors.
Glacier Hydrology in the Indian Himalaya: Effects of Climate Variability on Runoff Characteristics
Syed I. Hasnain, S. Ahmad, P. G. Jose, D.C. Negi and S. Tayal
Glacier Research Group, School of Environmental Sciences,
Jawaharlal Nehru University, New Delhi -1100 67
Meltwater derived from snow and ice fields in Himalayas is the major source of fresh water in the headwaters of major rivers such as the Indus, the Ganges and the Brahmaputra. Discharge characteristics and the factors controlling the runoff in a meltwater stream draining from Dokriani glacier, Garhwal Himalaya are examined for the summer ablation period between 1994 and 2000. Monsoonal precipitation over the lower part of the glacier and subglacial changes appears to be important factors controlling the shape of the discharge hydrograph. A majority of Indian Himalayan glaciers are nourished by precipitation during the summer-monsoon and therefore they are very sensitive to summer air temperature fluctuations. Last years’ summers have been particularly warm, as average air temperature has risen rapidly by more than 1.5°C, increasing year to year variability of river flow. In this present paper, a study has been conducted on climate change and its influences on glacier behavior and the quantity of discharge in rivers draining from the glacierised Himalayan basins.
Balance of Ecology: Source of Water Resources Development
Jit Narayan Nayak
Department of Civil Engineering,
Institute of Engineering,
T.U.GPO Box: 1175, Kathmandu, Nepal
With the aim to create a healthy population in the production process of new commodities an unconscious interaction between the human race and nature has caused a disproportional ecological balance of nature due to rise of the private ownerships on the means of social production for their unlimited satisfaction. The organic relationship between water and forest, and their dual influence upon water resources exploitation as well as the landscape’s health, is basically rooted within the natural environment of the south Asian region. For survival of the future generation the governments of the south Asian countries must have to think and plan their projects within an ecosystematic dimension which demands that all the governments should respect and protect the ecological and genetic processes that are the basis for the existence of people. In nature, normal functions are fulfilled by water just as blood provides many important functions for mankind. Water resources potential of the developing countries of south Asia remains unexploited to a large extent that hinders their socio –economic development. For intensive development of this potential there is an urgent need to preserve ecological balance in this region. Success in the work of protection and rational exploitation of the natural resources can be achieved only in a situation of high level of social consciousness of mass people. Only then, will all the natural resources of the south Asian countries be exploited rationally so that they would last not only for the present but also for the future generation. In order to achieve a sustainable balance of ecology in nature and, thereby, satisfactory socio-economic effect for mass people a paper titled: "Balance of ecology: source of water resources development" has been proposed herein for prosperity and wealth of the south Asian countries.
Preliminary Study on Water Quality of Indus River and other Aquatic Systems in the Ladakh Himalaya
Dorje Dawa and N. Madhavan
School of Environmental Sciences,
Jawaharlal Nehru University, New Delhi - 110 067
Samples of Indus river main channel and its head water tributaries (Zaskar, Shyak and Nubra), various small streams, glacial melt water, fresh (Tso Morari) and salt water (Pengong) lakes, Chumatang hotspring, were collected during monsoon (2000) across the Ladakh Himalaya have been analysed with the help of ion chromatograph for their major ion chemistry. Their Li and Sr concentration range from trace amount in glacial water to high values in salt water lake (Pengong) show with an average of 4ppm Li and 0.3ppm Sr. The Sr component in the source water of Indus (glacial water) is less (0.02 ppm). The calculated Ca/Na, Sr/Na ratios, and strontium compositions of these glacial melts show they represent the silicate endmember. These calculations suggest that Sr in the glacial melt water is of silicate origin. The Sr in main channel of Indus is 0.3 ppm and has to be supplied from other sources such as weathering of carbonates and evaporites. This study underscores the importance of weathering of silicates, carbonates, and evaporites in contributing to the Sr concentration and the source waters of the various smaller glacial melts to the major river Indus.
Patterns of Spring Discharge in a Western Himalayan Watershed
Varun Joshi and G.C.S. Negi
In the Himalayan mountains of India, problem of drinking water emerge during summer (April–June). Despite of the fact that these mountains provide life giving water to million of the downstream people through perennial river system, the inhabitants are compelled to collect potable water from far off distances, reduce water consumption, consume unhygienic water and face social conflicts. Sometimes one has to pay for water collection from a distance source by a labour. In mountains springs and seepages (locally called Naula) are the main sources of drinking water. The shortage of drinking water arises mainly due to drastic reduction in spring discharge during summer. The discharge fluctuations mainly depend upon the type of spring. Many factors may be attributed to the diminishing spring discharge, which include land use, geohydrological changes, reduce in water retention capacity, etc. Present paper deals with impact of rainfall and other characteristics of recharge zone on discharge of major springs in a Western Himalayan watershed. An attempt has been made to suggest recharge zone characteristics conducive for spring discharge to develop the water resources and meet the water demand of the people.
Impact of Engineering Interventions on the Soil Management –A Success Story
Indian Forest Service
Deputy Conservator of Forest
#2858, sector 37-C, Chandigarh
Explosions in population and land degradation are the two basic agrarian problems of India that have defied solution so far. On the initiative of the Union and the State governments, there have been many efforts for rehabilitating the degraded life support system especially water and land regimes through engineering interventions. Lower Shiwaliks in North India is one such fragile eco-system that has demanded attention of the government. Here Engineering interventions have shown good perceptible change in the socio-economic structure of the locals. The paper apart from commenting on the measures and their dimensions attempts to focus on the ecological principles that are the real tangible parameters of sustainability of the habitat. The paper also discusses the linkages of hill denudation with environment and poverty in the Sukhomajri area of the Shiwaliks. The watershed management techniques involved land leveling, use of improved seeds and fertilizers apart from growing of fruit and forage trees as per the requirement of the villagers. Involvement of the locals was stressed and practiced in all the activities. The project provided food security, forage security, fuel security, flood security and social security. A new concept of watershed management ONLY with the involvement of locals has emerged here for the restoration of the degraded eco-system.