PHYSICO-CHEMICAL WATER QUALITY PARAMETERS AND AQUATIC PLANT DIVERSITY OF DIPANG LAKE, POKHARA, NEPAL

Abstract

Dipang lake is the important but vulnerable lake of Pokhara valley due to mainly natural causes and other human activities. Understanding of different water properties is helpful in sustainable management of lake. The present investigation deals with the characterization of water quality parameters of Dipang lake situated in Pokhara- Lekhnath Metropolitan city, Kaski. The investigation was carried out on physical parameters like colour, odour, temperature and transparency while chemical parameters like pH, dissolved oxygen, free CO2, alkalinity, total hardness, nitrate and ammonia both seasonally (rainy, winter and summer) as well as source wise (inlet, middle and outlet). Present study highlights the natural variation of the different water quality parameters of the lake water seasonally as well as water source wise. But parameters were within the permissible limit for fishing, agricultural and domestic purposes. Statistically the recorded mean values of water parameters especially temperature i.e (27±1.76 °C in rainy to 10.95±0.55 °C in winter) and total hardness i.e (92±11.06 ppm in dry summer to 32.30 ± 6 ppm in winter) varies significantly (p<0.05) according to the season. Likewise, other parameters show slight fluctuations seasonally. The water parameters also affect the growth of some plant species especially Nelumbo lutea (Yellow lotus) which was found only towards the water inlet where the amount of ammonia is high 18±14.03 ppm.