Assessment of Anthropogenic Impact on the Water Bodies of South Asia Based on Mathematical Modeling Data (A Case Study of Ulsoor Lake, Bengaluru, India)

Abstract

Mathematical modeling of hydrothermodynamic, chemical, and biological processes has identified the potential causes of Lake Ursul (India) returning to a high trophic status after extensive restoration work. This is due to high nutrient content, which leads to very high phytoplankton primary production and biomass. This causes high oxygen consumption during the bacterial decomposition of organic matter and plankton respiration. In such a situation, short-term stable density stratification, which prevents the aeration of the bottom layers, is sufficient to completely deplete dissolved oxygen, leading to massive fish mortality. As a result of the restoration work, the influx of nutrients from the catchment area was reduced; that is, the reduction affected the external nutrient load. However, this was insufficient, as the internal nutrient load was enough to compensate for this reduction. Consequently, after a short-term improvement, the lake’s ecological state returned to its initial hypereutrophic state.