ABSTRACT
This paper presents our study and assessment on reservoir sedimentation issues as well as desiltation plan and approaches for two reservoirs, namely Pillur in south (Tamil Nadu) and Maneri Bhali I in north (Uttarakhand) part of India. The alteration in nature, magnitude and severity of the problems in these two entirely different reservoirs demonstrates the complexity and uniqueness of the problems, indicating need for distinctive and tailor-made approaches to address them. In addition to loss of reservoir storage capacity, the sedimentation seems to be leading to malfunctioning and damage of the structures and apparatuses, e.g. intakes, scour-sluices, spillway glacis, roller buckets, cut-off walls, gates etc. In both reservoirs, upstream and downstream effects are of major concerns, and thus environmental, ecological and social compliances are supposed to be ensured while preparing remedial measures and plan. Since there are not much data, analyses have been made based on brief field reconnaissance and collection of information. Additionally, attempt has been made to demonstrate application of numerical model so as to replicate some synthetic scenarios associated with hydrodynamic and morphological impacts of different interventions and measures, such as morphological evolution along downstream river reach, propagation of released/replenished sediments, effects of sediment removal from the reservoir as well as effects of traps. This study demonstrates applicability of a modelling tool to analyse various scenarios, presumptions and hypotheses as well as replicating effects of structural, non-structural and recurrent measures and interventions.
