Impact of dam construction on aquatic biodiversity and mitigation strategies

Abstract

Dam construction has long been regarded as a vital tool for water resource management, hydroelectric power generation, and flood control. However, it also poses significant ecological challenges, particularly to aquatic biodiversity. This study evaluates the ecological impacts of dam construction on aquatic biodiversity, water quality, and fish migration patterns while identifying effective mitigation strategies. Field surveys were conducted across upstream, mid-reservoir, and downstream zones of selected dam-affected river systems. Biodiversity indices, including the Shannon-Weiner Index and Simpson Diversity Index, were calculated, and hydrological models (SWAT and HEC-RAS) were employed to assess flow regime changes. Radio telemetry and PIT tagging techniques monitored fish migration patterns, while water quality parameters such as dissolved oxygen (DO), temperature, nitrate, and phosphate concentrations were measured in situ.The results revealed a significant decline in biodiversity indices in mid-reservoir zones (Shannon-Weiner Index = 2.1) compared to upstream zones (3.5). Migratory fish species exhibited reduced success rates in navigating fish ladders, with only 45% achieving successful passage. Water quality parameters showed significant spatial variability, with elevated temperatures and reduced DO levels in mid-reservoir zones. Regression analysis demonstrated a strong negative correlation (R² = 0.97, p