A beel thicky infested with water hyacinth
A beel thicky infested with water hyacinth
A beel thicky infested with water hyacinth
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an effective way of using natural resources for the beamnmt of man. However, the<br />
ecosystem processes in open wata bodies me usually vay complex due to the<br />
interaction of an array of physical, chanical and biological processes. Since the<br />
synergistic effect of these factors influence the dynamics of biotic communities living in<br />
these <strong>water</strong> bodies and govern the rate of output of harvestable biological material, it is<br />
oRen dlficult to link their fish production potential <strong>with</strong> any particular ecological<br />
parameters. The <strong>beel</strong> ecosystem is extraordinarily complex <strong>with</strong> wide temporal and<br />
spat~al variations of many key pmeters. Among the various factors that influence the<br />
wetland ecosystem arc depth, nature of catchment area or river basin, precipitation and<br />
duration of connection to river etc.<br />
Ecosystem processes in a <strong>beel</strong> is determined by a number of factors which can be<br />
brought under three broad heads<br />
Morphometry and hydrodynamics<br />
8 Physico-chemical properties, and<br />
b~ological characteristics<br />
Morphometry and hydrodynamics<br />
The main morphometric features that influence the productivity of <strong>beel</strong><br />
ecosystem are shoreline. area, dcpth and slope. These, in turn, are closely linked <strong>with</strong><br />
the hydrodynamics of wetlands. Water renewal pattern is often modified by a number of<br />
natural and man-made processes. The important morphometric and hydrodynamic<br />
characteristics of different <strong>beel</strong>s scattered over Brahmaputra and Barak valley, studied<br />
by CIFRI over the last few years, are described below:<br />
Therc are thm main sources of <strong>water</strong> input into the <strong>beel</strong> ecosystem vr:. owrsp~ll<br />
from [he river channel, sut$ace/low and regeneration. Since the state of Assam receives<br />
one of the highest rainfalls in the world, the former two arc responsible for <strong>water</strong><br />
renewal in the <strong>beel</strong>s in this State. Rainfall directly fills the lake or rain on the riverine<br />
catchment feeds the parent river. Surface w-off and incnsse in river height due to<br />
inflow of rain <strong>water</strong> from the upper stretch, cause inundation of the floodplains. often<br />
causing resumption of connection between <strong>beel</strong>s and parent rivers. The <strong>water</strong> gain or<br />
exchange of wata in Assam takes plnce during southwest monsoon when the