Wasim Ul Haq Qureshi
Student
Symbiosis Institute of Geoinformatics,
Email: wasim_qur@yahoo.co.in
Water quality in inland lakes is often described in terms of tropic state (nutritional state). A lake with increased growth of phytoplankton is called a “Eutrophic Lake”. The main reason for eutrophication in most lakes is phosphorus loading. “Eutrophication” is the general ageing process of lakes. It is a natural process expressed in terms of geological time. However, this process is greatly accelerated when influenced by human activity and may result in polluted water conditions. Such processes are termed as “Cultural Eutrophication” and are intimately related to land use/land cover.
Different users of lake prefer different level of macrophytes (large aquatic plants) in lakes. Most recreational users of water bodies, swimmers, boaters and water skiers prefer lakes relatively free from excessive macrophytes and algae. On the other hand, persons interested in fishing generally prefer some macrophytes. Moreover, large concentrations of blue-green algae have an unpleasant odor that is offensive to most people, especially during “blooms”, or periods following active algal growth.
Concentrations of free floating algae are a good indicator of a lake’s trophic status. Excessive concentrations of blue-green algae are especially prevalent under Eutrophic conditions. Green algae are typically present at any point in the seasonal cycle of lakes. Because the different broad classes of algae have somewhat different spectral response patterns, aerial and space imaging can distinguish them. By spectral response, we mean the response of an object to the incident wavelength upon it. Each object responds differently to the different wavelengths. This is described by its unique response called Spectral Signature. Similar work has been done in past by many students and scholars. The work of J.M. Mironga (GIS and Remote Sensing in the Management of Shallow Tropical Lakes) on Lake Marion, Kenya finds out various ways of using GIS and RS in monitoring spreading weeds in the lake under study. We’ll extend this work to the lakes of Kashmir, like Wular and Dal Lake, which are under different environmental conditions.
The data collected from various sources (Aerial Photographs, Satellite Images, Field Surveys and stored databases) will be integrated and analyzed in a GIS to provide useful spatial information and temporal changes over large geographic areas affecting the structure and function of lakes.
The aim of this work is to assist the concerned authority in analyzing the spatial distribution of ‘Eutrophication level’ in a lake. This will help them in taking decisions regarding ‘usage of lake for different purposes’ and also take countermeasures to ‘control pollution level’ of the water bodies.