Trophic Status of Shanti Sagara Reservoir: Implications on Nutrient Management in Reservoir Catchment

V. Rohan Desai *

Department of Environmental Engineering, University BDT College of Engineering, Davangere, Karnataka, India.

Tejaswini Nikhil Bhagwat

Department of Civil Engineering, University BDT College of Engineering, Davangere, Karnataka, India.

*Author to whom correspondence should be addressed.


Water quality assessment of Shanti Sagara reservoir for drinking water supply and for water allocation to meet the demands in the semiarid climate is aimed. Seasonal water sampling (Pre monsoon, December 2021 & Post monsoon, May 2022) at 2 depths to investigate physico-chemical parameters and assess the Water Quality index based on IS 10500: 2012 is found to be poor in pre monsoon, December 2021 and very poor in post monsoon, May 2022. Trophic status of the reservoir assessed based on Carlson’s Trophic State Classification (Secchi Depth, Total Nitrogen and Total Phosphorous) indicated that the reservoir is Hypereutrophic for Post Monsoon. This calls for assessment of internal nutrient load (silt characteristics) and external loading from the reservoir catchment (fertilizer from agriculture land) and the domestic water and the sewage water has contributed to high concentration of phosphorous (P) in Rudrapura and Jakli near Somalapura.

Soil texture (sandy clay, silty loam, silty clay and sandy clay loam) in the reservoir catchment compliments high concentration of suspended sediment that increasers the turbidity in the reservoir. Turbidity present in the water alters the taste, colour and odour of the water and oxygen from the surface cannot be mixed to the bottom layer and oxygen is not released by photosynthesis in absence of light penetration (high turbidity levels) resulting in anoxic condition. Total Nitrogen (TN) in the catchment soil that contributes to the bottom of the reservoir is found to be high (201-217 kg/acre). Agriculture runoff in the month of (May, 2022) owing to precipitation results in high sediment concentration, that contributes to high nitrogen levels in the reservoir.

Nutrients in suspended Sediments that have entered the reservoir altered the nutrient cycle in the reservoir ecosystem. High nutrient concentration in the silt characteristics i,e total nitrogen (159-168 kg/acre) and phosphorous (10.1-13.4 kg/acre) is due to stratification caused do level to low in hypolimnion layer and anoxic condition during summer resulting in growth of Phytoplankton the eutrophication. The suggested nutrient management strategies for the reservoirs catchment are optimizing nutrient application to the crop land, microbial water treatment before supplying it for drinking purpose, soil conservation structures in the reservoir catchment to restrict sediment entry to the reservoir and sewage treatment plant for the rural settlement.

Keywords: Reservoir water quality, total nitrogen (TN), total phosphorous (TP), secchi depth (SD), water quality index (WQI), nutrient management

How to Cite

Desai, V. Rohan, and Tejaswini Nikhil Bhagwat. 2022. “Trophic Status of Shanti Sagara Reservoir: Implications on Nutrient Management in Reservoir Catchment”. Asian Journal of Environment & Ecology 19 (3):32-47.


Download data is not yet available.


Gunkel G, Lima D, Selge F, Sobral M and Calado S. Aquatic ecosystem servicesof reservoirs in semi-arid areas: sustainability and reservoir management. Transactions on Ecology and the Environment. 2015; 197:1-14.

Kummu M, Ward PJ, Moel HD, Varies O. Is Physical Water Scarcity a new phenomenon?. Global assessment of water shortage over the last two millennia. Environmental Research Letter. 2010;5(3): 1-14.

Mady B, Lehmann P, Gorelick SM, Or D. Distribution of small reservoirs in semi- arid regions and associated evaporative losses. Environment Research Communications. 2020;2:1-10.

Luis AD, Cabral P. Small dams/ reservoirs site location analysis in a semi- arid region of Mozambique. Intrnational Soil and Water Conservation Research. 2021;9: 381-393.

Santisteban M, Grande JA, Torre ML, De la Valente T, Ceron JC. Acid mine drainage in semi-arid regions: The extent of the problem in waters of reservoirs in the Liberian pyrite Belt (SW Spain). Hydrology Research. 2015;46(1):1-12.

Cerco CF. Conowingo reservoir sedimentation and Chesapeake Bay: State of the science. Journal of Environmental Quality. 2016;45:882-886.

Chilagane NA, Kashaigili JJ, Mutayoba E, Lyimo P, Munishi P, Tam C et al. Impact of land use and land cover changes on surface runoff and sediment yield in the little Ruaha River catchment. Journal of Modern Hydrology. 2021;11:54-74.

Bhagwat TN, Lamani SN. Irrigation Water quality assessment in vanivilas sagar reservoir catchment. Journal of Research in Environmental and Earth Science. 2019;5(2):10-20.

Alahiane N, Elmouden A, Aithal A, Boutaleb S. Small dam reservoir siltation in the Atlas mountains of Central Morocco: Analysis of factors impacting sediment yield. Environmental Earth Science. 2016; 75:10-35.

Bergi J, Trivedi R. Seasonal variation of nutrients that influence the growth of Cyanobacteria in surface water reservoirs of river Tapi. Journal of Geoscience and Geomatics. 2022;10(1):18-30.

Cloutier RG, Sanchez M. Trophic status evaluation for 154 Lakes in Quebec, Canada: monitoring and recommendations. Water Quality Research of Journal Canada. 2007;42(4): 252-268.

Ghodrati M, Ghazaryan S. Agriculture water supply in semi-arid zone by underground dams. European Journal of Experimental Biology. 2013;3(3):706-711.

Hickey CW, Gibbs M. Lake sediment phosphorus release management decision support and risk assessment framework. New Zealand Journal of Marine and Freshwater Research. 2009;43(3): 819–856.

Huang J, Ji M, Xie M, Wang S, He Y, Ran J. Global semi-arid climate change over last 60 years. Climate Dynamics journal of Springer Science Media. 2016;46: 1131-1150.

Acharya S. Land use and land cover changes in the catchments impact the ecosystem in Phewa, Begnas and Rupa lakes, Nepal. Journal of Nepal Geological Society. 2020;60:195-205.

Istvanovics V. Eutrophication of lakes and reservoirs. Encyclopedia of Inland Waters. 2009;1: 157-165.

Mama CN, Okafor FO. Siltation In reservoirs. Nigerian Journal of Technology. 2011;30(1):1-6.

Filstrup CT, Downing JA. Relationship of chlorophyll to phosphorous and nitrogen in nutrient-rich lakes. Inland Waters of Journal. 2017;7(4):385-400.

Andaya LY. Water in the study of Southeast Asia. Kemanusiaan the Asian journal of Humanities. 2018;25(1):21-38.

Khadanga MK, Mishra RK, Sahu BK. Assessment of pollution and ecological risk index of heavy metals in the surface sediment of estuary and the coastal environment of Bay of Bengal. Journal of Environmental Informatics. 2022;39(1): 35-48.

Sharma DK. Impact of dams on river water quality. International Journal of Current Advanced Research. 2015;4(7):176-181.

River system and reservoir water quality: Case study of mazowe catchment, Zimbabwe. Copernicus Publications on Behalf of the International Association of Hydrological Sciences. 2018;377: 57-66.

Wenjie L, Zhuo D, Yi X, Shengfa Y, Wei Y. Influence of sedimentation on nitrogen and phosphorus in the three gorges reservoir. International Journal of River Basin Management. 2020;9(1):1-13.

Winton RS, Alamita E, Wehrli B. Reviews and syntheses: Dams, water quality Andtrophical reservoir stratification. Bio-geoscience Journal of European Geo-science. 2019;16:1657-1671.

Nikolai SJ, Dzialowski AR. Effects of internal phosphorous loading on nutrient limitation in a eutrophic reservoir. Elsevier Journal of Limnologica. 2014;49:33–41.

Zhou Z, Huang T, Ma W, Li Y, Zeng K. Impacts of water quality variation and rainfall runoff on Jinpen Reservoir, in Northwest China. Water Science and Engineering. 2015;8(4):301-308.

Ozkundakci D, Hamilton DP, Trolle D. Modelling the response of a highly eutrophic lake to reductions in external and internal nutrient loading. New Zealand Journal of Marine and Freshwater Research. 2011;45(2):165-185.

Ramesh N, Krishnaian S. Water quality assessment of Bellandur Lakes in Bangalore City, Karnataka, India. International Journal of Engineering Research and Technology. 2014;3(3): 1-5.

Junior JRDM, Amado AM, Vidal LDO, Mattos A, Becker. Extreme droughts drive trophical semi-arid Eutrophic reservoirs towards CO2 Sub-saturation. Acta Limnologica Brasiliensia. 2018;30(101): 1-20.

Song K, Adams CJ, Burgin AJ. Relative importance of external and internal phosphorus loadings on affecting lake water quality in agricultural landscapes. Ecological Engineering. Tundu C, Tumbare J and Onema JMK. Sedimentation and Its Impacts/Effects on. 2017;108:482-488.