The document summarizes a study on the physico-chemical characteristics of Beeshazar Lake in Chitwan, Nepal. It was declared a Ramsar site in 2003 for its biodiversity. The study analyzed water quality, surface soil parameters, and tree species composition around the lake in three seasons. Water quality testing found the pH and hardness were suitable for organisms but dissolved oxygen was low. Nutrient levels ranked the lake as eutrophic to hypereutrophic. Surface soil was acidic with high phosphorus. Eleven tree species from nine families were recorded, with Shorea robusta dominating.

1. A STUDY ON PHYSICO-CHEMICAL CHARACTERISTICS
OF BEESHAZAR LAKE, CHITWAN, NEPAL
-Ujwal Bastakoti
M.Sc. Thesis
Central Department of Environmental Science, TU, Nepal
ABSTRACT
Dissected fern shaped Beeshazar Lake is within the Barandabhar Corridor Forest of Chitwan
National Park, Chitwan, Nepal. Beeshazar Lake System is an intricate ecological system with
a variety of physical, hydrological and vegetative characteristics. It was declared as a Ramsar
site in 2003 because of global biodiversity perspectives as defined by Ramsar criteria,
"characterized by an extensive, typical oxbow lake system of the tropical Nepal inner Terai,
lying inside the buffer zone of the Chitwan National Park, a World Heritage Site, providing
excellent habitat conditions as a water hole and corridor for endangered wild species and
assemblage of some rare and endangered large mammals, reptiles and monogeneric plant
species important to conserve for the conservation of genetic diversity.” Wetlands of Nepal
are in extreme pressure due to the various anthropogenic activities and lack of proper
ecological monitoring from the authentic body. Physico-chemical characteristics of
Beeshazar Lake (3 sites), surface soil parameters (10 sites) and quantitative analysis of tree
species (20 plots of each 20X20 m2) of the forest around the lake were performed to assess
the general ecological status of the lake system. The present investigation was carried out in
three different seasons of the year 2006 i.e. winter season, monsoon season and autumn
season. The status of water quality is one of the major factors that determine the health of a
wetland ecosystem. The average pH value observed in the present investigation in the water

2. of the lake indicated that the water was optimal for most organisms but the observed
dissolved oxygen value was less than the tolerance limit of 6 mg/L. The average total
alkalinity value showed that the water of the lake had fairly high total alkalinity but the
average total hardness value showed that it was suitable for the growth of aquatic organisms.
The observed value of transparency, total nitrogen and orthophosphate ranked the lake at
eutrophic to hypereutrophic state in different seasons. The high concentration of total
nitrogen and orthophosphate was the major factor for the degradation of wetland habitat in
Beeshazar Lake leading to the gradual conversion into marshy areas. The luxuriant growth of
aquatic macrophytes and their subsequent decomposition after die-off was lowering the depth
as well as causing anoxia condition in the lake which might be vulnerable to aquatic lives.
The values of certain water parameters (pH, conductivity, surface water temperature, free
CO2, total solids, GPP, chloride, orthophosphate, nitrate and total nitrogen) were observed
highest in monsoon season; while total alkalinity, DO and transparency values were observed
highest in winter season and total hardness value was observed highest in autumn season. In
the present investigation the surface soil of the forest around Beeshazar Lake was observed
acidic with sandy loam texture. The phosphorous content in surface soil was observed high,
while potassium and nitrogen content were medium. The observed organic matter in the
present investigation indicated the low soil fertility of the forest floor around the lake. The
values of certain surface soil parameters (O.M., phosphorous and potassium) were observed
highest in monsoon season; while soil conductivity and total nitrogen values were observed
highest in autumn season and soil pH value was observed highest in winter season. All
together, 11 tree species belonging to 9 families were recorded in the forest around the lake
with the dominancy of Shorea robusta. The total density of the tree species recorded in the
present investigation was 372.50 pl/ha; with total basal area of 28.3246 m2/ha.; total volume
of 225.6159 m3/ha and total above ground biomass of 196.6291 ton/ha.
Key words: Wetland, physico-chemical parameters, seasonal variation, surface soil, tree
biomass