PERFORMANCE ANALYSIS AND DESIGN OF FISH PASSES

Abstract

Migration is one of the elementary behaviour of several fish species. Some fishes swim thousands of kilometres from rivers to sea or vice versa to their spawning grounds. Sometimes various fish species and invertebrates take on short term or small scale migration instead of long migrations from one river part to another for certain biological needs of their life cycles. The construction of dams, barrages, weirs or navigation locks on a river for diverting, storing water for hydropower, irrigation, navigation and flood control purposes block or delay the migration of fish species causing the decline and sometimes their extinction as their biological life cycle depends on the longitudinal movements along the stream. Further the passage of the fish through the hydraulic turbines and the spillways can has high mortality causing significant loss to their population. For the mitigation of the same, fish passes are constructed at the hydraulic structures and are designed to dissipate the energy of flowing water in order to decrease the * velocity of water and increase the depth of water. The fishways are very important to restore the free passage for the fish species and other aquatic species in rivers. Fishways are the structures to aid the aquatic fauna to overcome obstacles that block their journey up or down the river. Their effective working is mandatory to reclaim the free river passages. There are very limited studies on the performance of existing fish passes. However there are guidelines frorn USBR, FAQ, DWA and European Environmental Agency for designing the fish passes. Fish migration and various types of fish passes in Uttarakhand, Punjab, l-limachal Pradesh, Haryana and Orissa have been studied and analyzed. For evaluating the performance physical measurements and hydraulic principles were studied. While designing the new fish passes, the dominating fish species have been identified and as per their sizes, dimensions of the fish passes have been fixed. Different kinds of fish passes have been designed for the same site so that anyone can be taken up depending on further investigations and relative advantages and disadvantages of the fish passes. Factors affecting the selection of a particular fish pass at a site have been addressed. Detailed drawings and alignment of the fish passes have been presented. Based on this study conclusions are drawn on the performance of the fish passes, modifications to the designs of existing fish passes have been made and some recommendations have also been made for making the fish passes more effective and efficient.