Theme Basic Concepts in Echohydrology

Ecohydrology: Rediscovering Freshwater Ecology
Brij Gopal and Malavika Chauhan
School of Environmental Sciences,
Jawaharlal Nehru University, New Delhi 110067, INDIA
brij@jnuniv.ernet.in

Ecology is essentially a biological discipline that deals with the reciprocal relationships between all living organisms and their non-living environment. These interrelationships are usually investigated at three levels of biological organization species populations, communities and ecosystems. Freshwater ecology has dealt with the concerns of ecohydrology over several decades and has developed several concepts that integrate hydrological and ecological processes at ecosystem to landscape level. River floodplain interactions and the impacts of human activities in watershed on stream ecosystems have been investigated in great detail. Ecohydrology can benefit from these studies.


Impact of Forest Clearing on Hydrology: Mathematical Modeling of Khageri River
Narendra Man Shakya
Coordinator,
Post Graduate Program in Water Resources Engineering,
Institute of Engineering, Nepal
nmsioe@yahoo.com

Intervention in one sub-process of the hydrological cycle may have adverse effects on other sub-processes such as surface flow responses and groundwater. Vegetation cover plays an important role in determining the extent of this effect. To evaluate the impact of changes in land-use and vegetation on hydrology, models are increasingly being used. This paper analyses the potential disruption in the periodicity and low volume of the Khageri River in Chitwan District, Nepal, caused by clearing of forest in the river catchment in order to resettle population. The University of British Columbia Watershed Model (UBC) is used to simulate flow. The University of British Columbia Watershed Model (UBC) is used to simulate flow. The impacts of flow alternations on the performance of an existing irrigation system are discussed Finally, larger implications for water management are pointed out.


Impact of Aquaculture on Fresh Water Bodies: A Case Study from Nellore District, Andhra Pradesh, India
K. Shivkumar1, G. Biksham2 and R. Ramesh3
1AMD Complex, Civil Lines, Nagpur, India.
kshivkumar@satyam.net.in
2World Wide Fund for Nature, Gland, CH 1196, Switzerland.
bgujja@wwfint.org
3Institute for Ocean Management, Anna University, Chennai, INDIA
rramesh_au@hotmail.com, ramesh@annauniv.edu

Aquaculture was traditionally practiced along coastal areas as an important source of food, which has now transformed into an industry. In recent times a number of cultivable agricultural lands are converted to shrimp farms and several thousand hectors of mangrove forests are destroyed. Improper handling of aquaculture activities has polluted coastal environment causing irreparable damage. Andhra Pradesh contributes to nearly half of countrys shrimp production and the coastal areas of Nellore and Prakasham districts are the main producers. South of Nellore town, Kandaleru River flows from west to east and forms a creek/estuary. Along the estuary a number of shrimp farms have mushroomed in recent years. Buckingham Canal a fresh water canal cuts across the coastal districts has become a dumping site for all the pollutants of fish and prawn ponds and turned as an effluent drain.

An attempt is made to assess the pollution impact due to aquaculture. Water samples have been collected along Kandaleru River and Buckingham Canal in three phases such as prior, at the time of start, and harvesting of shrimp culture. Specific conductance (EC), total dissolved solids (TDS), Na, Mg, Ca and Cl have increased along the River course and Canal with higher values nearer to the aquaculture activities. The level of pollutants has increased two times of the permissible limits and fresh water in the river and Canal has turned to brackish water.


Nutrient Dynamics With Special Reference to Phosphorus in an Enclosed Bay of Seto Inland Sea (Japan)
Joyce W. Njenga
Jomo Kenyatta University of Agriculture and Technology,
Box 62000, Nairobi, Kenya

Phosphorus cycle was studied for a period of one-year (April 1990- March 1991) in a semi-enclosed bay (Etauchi) of seto Inland Sea, Japan. Various forms of Phosphorus were studied, which includes dissolved inorganic phosphorus (DIP), particulate phosphorus (PP), dissolved organic phosphorus (DOP) and total phosphorus (TP). Results exhibit pronounced seasonal variation. The surface layer was depleted with DIP (undetectable-0.1 g/l) and bottom layer rich in DIP range (0.2- 97 g/l) during spring and summer. The pattern changed to a homogeneous average distribution of 0.2 g/l during autumn and winter seasons. The variation of PP concentration was not clearly marked between the surface and the bottom layer as both had a range of 0.1-0.67g/l and 0.1-0.63g/l respectively in spring and summer season. Lower homogenous distribution (less than 0.2g/l) was observed throughout the water column during autumn -winter. Generally, DOP was uniformly distributed in the water-column throughout the year (range 0.1-0.2g/). Sediment incubation experiments carried out in the month of July and December indicated an increase in TP content in the overlying water in July and a decrease in December. Thus, desorption/absorption process was well pronounced at the bottom layer. TP concentration in rainwater was very low (<0.2 g/l) which indicates that the contribution of precipitation to the phosphorus content in the bay was minimal.


Water Management: Challenges for the Future in Recycling Societies
Janusz Niemczynowicz
Professor at the Department of Water Resources Engineering,
University of Lund, Box 118, S - 221 00 Lund, Sweden
janusz.n@tvrl.lth.se

General and urban hydrology constitutes a scientific base for urban water management. This applied science will have an increasing role to play on the way to sustainability of human societies. Facing present growth of urban population, it is increasingly difficult to find and utilize new sources of water necessary to satisfy growing water demand. Safe drinking water, the most important life-supporting commodity, must be accessible to all people independently of their social and economical status and place of living. Water delivery for the residents of peri-urban and squatter areas, living in ultimate poverty, should be considered equally important as for those wealthy. To eliminate worse kind of poverty, the poverty of lacking clean water, should be a first priority target for scientists, regional and local administrators and, especially, people dealing with regional and local water management. Growth of urban areas and installation of technical water-related infrastructure brings significant changes in physical properties of land surface, increasing integrated vulnerability of life supporting systems such as local and regional water resources, agricultural land and rural agricultural food producing systems. The shape and performance of technical solutions used in water management depends on climate as well as on social, economical and cultural conditions. Collection of local hydrological data, calculations and modelling constitute a necessary fundament for meaningful water management in urban areas and in entire river basins. Future challenges in urban water management include elimination present pollution sources development of new technical solutions as well as logistic and organizational methods in order to eliminate present problems and create future opportunities. Humanity with its governments, population together with scientists stands now in front of a challenge of immense dimension and dignity: to exchange present linear material flows within all sectors of the societies with circular flows. Creation of "recycling society" will not be easy. Current and emerging challenges are discussed in the paper.


Modelling Potential Soil Erosion in Lake Nakuru Drainage Basin
S. K. Murimi and H. Prasad Department of Geography, Kenyatta University, P.O. Box 43844, NAIROBI, KENYA haushila@hotmail.com

Geographic Information Systems (GIS) technique was used to map soil erosion potential in the drainage basin of Lake Nakuru. Two sets of georeferenced data on surface factors controlling soil erosion by water in a watershed were manually coded and then analysed as one of ten classes ranging from zero for the lowest values to nine for the highest values. The two sets of data, (that is, Topographic and Landcover information) were merged on a cell to cell basis throughout the basin to locate areas where combinations of site characteristics indicate high, low or medium soil erosion potential. Stream network data for each grid square (cell) of 1km2 was matched with corresponding soil erosion potential value to identify areas with active stream processes.

Areas identified as having high soil erosion potential are located in the steep headwater regions. These areas were originally under natural forest cover but have since been cleared and subdivided into small plots which are under intensive farming of annual crops. The stream network extent, and hence drainage density in the headwater regions was also found to be high. The streams to the depositional lowlands and into the lake easily transport this means that the vast quantities of topsoil removed from the land surface in such areas. However, further work is needed to establish the precise contributions of other factors such as, soil erosion and conservation practices to soil erosion by water if strategies are to be devised to save soil and water resources in the Lakes environment


Various Fool Proof Methodologies for Chemical Analysis in Ecohydrology
R. Arthur James and G. Muthuraman
German Technical Co operation (GTZ)
Center for Environmental Studies
Anna University, Chennai 25
james_au@lycos.com

This paper deals with various analytical procedures with their merits and demerits in respect to ecohydrology. The importance of quality control (QC) and various QC tools for chemical analysis are discussed.


Geochemical Evaluation of River Sediments for Water Quality Models
B. C. Raymahashay
Department of Civil Engineering
Indian Institute of Technology,
Kanpur 208016, India.
bcr@iitk.ac.in

The geochemical approach to water quality models requires an understanding of the fundamental principles of rock weathering and erosion in the catchment area. Relative mobility of rock-forming elements controls the mineralogy of suspended sediments as well as the solute concentration levels. Therefore, the suspended and dissolved loads of the river are related to each other. This relationship can be further quantified in terms of the rates of mechanical erosion and chemical weathering. As rock-weathering reactions involve consumption of atmospheric CO2, these processes influence global climate and the carbon budget of deltaic sediments.


Flood Hazard Management of Matatila Dam in the Bundelkhand Region, Uttar Pradesh
Purnendu Sinha, V. K. Agarwal and R. K. Sanwal
Geological Survey of India, Lucknow
gsiluck@up.nic.in

The 35-meter high Matatila dam across river Betwa was constructed way back in 1958. The dam has a composite section comprising 6km long earthen embankments spread on the left and right abutments and 220 m wide overflow section to pass off a flood discharge of 15859 m3/sec. The dam is founded on the rocks of Bundelkhand Granitoid Complex and generates 45 MW of power. Due to construction of another 45 m. high Rajghat dam, located abeut 50 km. in its upstream, Matatila dam would have to pass off an additional flood discharge of 38,997 m3/sec of water released from Rajghat dam. In the existing design, it would not be possible, unless remodel-ling of the Matatila dam is done, otherwise the excessive flood discharge would over - xopple the Matatila dam resulting in failure of the structure. Different alternatives to pass the enhanced dischargevre discussed in this paper.


Hydrological and Soils Impacts of Natural and Anthropogenic Forest Disturbances
B. K. Purandara1, B. Venkatesh1, M. Bonell2 and R. Jayakumar3
1Scientist, National Institute of Hydrology, Belgaum 590 001, India.
bvenki30@yahoo.com
2Chief , Hydrological Process and Climate Section,
Division of Water Sciences, UNESCO, Paris, France.
3 Program Officer, UNESCO, New Delhi, India.
r.jayakumar@unesco.org

Watershed is a natural physiographic or hydrologic unit where land, water and vegetation interact in a perceptible manner. Watershed has a number of distinct characteristics in determining the functioning of a watershed. Watersheds may have pure or mixed land use, comprising of agriculture, forests, grasslands, wastelands or mixture of these. The hydrological functioning of vegetated (forest) watersheds in turn is influenced by the type of vegetation, its extent and management. Forests may occupy smaller or greater fraction of watersheds. The upland watersheds have relatively more area under forest which have influence on the hydrological behavior of watersheds. In the present study, an attempt is made to understand the influence of various hydrological parameters under different forest covers. The study has been carried out in two sub-basins of river Krishna, namely, Malaprabha and Ghataprabha catchment having different land covers and in a small-forested watershed (Barchi). The study include rainfall analysis, erosion aspects with reference to undisturbed forests and field determination of infiltration, and soil moisture characteristics. The study revealed that there is a marked variation in hydrological parameters due to changes in geomorphology, land use and soil type.


Geochemical Studies of Some Kumaun Himalayan Lakes
G. J. Chakrapani
Deaprtment of Earth Sciences,
Indian Institute of Techonology,
Roorkee -247 667 (Uttaranchal)
gjcurfes@rurkiu.ernet.in

Lakes with their clear-cut boundary represent one of the most versatile eco- systems on the Earth. Like any other aquatic ecosystems, lakes are characterised by inputs and outputs of materials and hence represent an ongoing chemical process. However, there is limited mobility of lake materials as compared to rivers or oceans. The water output in lakes is mostly through evaporation and outlet streams. The sediments that are carried to the lakes by catchment erosion, get progressively sedimented to the bottom of the lake. The rapid interaction of sediment and water, aided by the rich biological activities, makes lakes an interesting natural laboratory.

The Kumaun Himalayan region is dotted with several natural and man-made lakes. The present study reports on the studies carried out in four major lakes in the region, namely Nainital, Bhimtal, Sattal and Naukuchiatal. The lakes have tectonic origin and are characterised by mostly silicate and carbonate lithology in the catchments. Water chemistry is dominated by Ca, Mg, HCO3, an indication of weathering of carbonate lithology. The dissolved trace metals and potential pollution loading in the lakes are varying, while Nainital shows a loading of 7.25, Bhimtal is the least (2.3). The Nainital is also characterised by high chemical index of alteration in sediments, reflected by its high carbonate and clay minerals contents. The 87Sr/86Sr ratios in the lakes are very high (>O.72), with samples from the Sattal are extremely radiogenic (>O.82), similar to many Himalayan rivers. The 87Sr/86Sr in sediments show distinct trends for silicate and carbonate weathering.