11. EFFECTS OF DAM ON FISHERIES
Hydro dam of Tinau River is located at Dovan, about 4 km away from Butwal, for producing hydroelectricity of 1000 kilowatt. This hydropower plant was established in 2022 B.S. by Butwal Power Company with the financial support of UMN to Nepal which was completed in 2032 B.S. In B.S. 2037 it was handover to Nepal Electricity Authority. There is only one iron gate especially used to direct the flow of water towards the turbine through tunnel. The powerhouse is located near the Siddhababa temple which is approximately 1 km away from the dam.
The effect of dam in Tinau river is more pronounced and has affected the abundance and distribution of fish population in the river. The dam in Tinau river has obstructed the seasonal migratory fishes from the Terai as well as local migratory fishes from the lower parts of Hilly region. According to the local people and fishermen, before the establishment of dam in the river, shoals of Gounch (Bagarius bagarius) and Thedi (Labeo angra) used to visit the areas above dam, and now they are completely disappeared from this area while they were reported from the lower region by fishermen in the month of July during the present investigation period.
The dam is generally disadvantageous to current loving and migratory fishes and also has reduced the surface area of fishing water to downstream. At the place of dam the course of river channel is directed towards the west bank of river where the tunnel has been made and there is absence of reservoir (Photo 18 and 19). A continuous flow of water is regulated to the downstream from the dam. Many current loving species of fishes can not cross the physical barrier of the dam as a result their upstream migration have been checked and many good sized Gounch (Bagarius bagarius), Thedi (Labeo angra), Jalkapoor (Pseudeutropius sps) have ceased to visit the upstream reaches of the river. Similarly the number of upstream migrant like Tor sps are reduced considerably in the downstream while the fishes which are totally inhabiting in low water are not affected and have got a good hydro biological condition such as Sidre (Puntius sps), Fageta (Barilius sps), Gadela (Noemacheilus sps) and Buduna (Garra sps). they have undergone a rapid increase due to the absence of their predatory fishes like Tor tor etc. As a result, the abundance of large sized migratory fishes have been gradually replaced by small fishes, certainly such a replacement reason plays a negative role in fishing occupation and finally fishermen are enforced to do other baseless jobs to maintain their lives.
No environmental impact assessment (EIA) of Tinau Hydroelectric Project before the establishment of hydro dam was conducted. Therefore, the present author could not study the comparative study of fish biodiversity before and after the dam construction. In the Tinau Hydroelectric Project only engineering feasibility study was performed. There is no doubt that the Tinau river system has undergone great many changes and structure and function of natural water courses as well as its physical, chemical and biological characteristics. |
