Abstract
In the Lower Gangetic Plain of West Bengal, the furious monsoon flood of Damodar River is a recurrent hydrometeorological phenomenon which is now intensified by the human activities. At present, the flood regulation system of Damodar Valley Corporation (DVC) is not capable of managing gigantic inflow water (which appeared as surface runoff and channel flow) coming from the wide fan-shaped upper catchment of Damodar River. As a result, the lower basin of Damodar (covering Barddhaman, Hooghly, and Howrah districts of West Bengal) annually experiences low to high magnitude of floods and overflow condition because the existing canal system, streams, palaeochannels, and Damodar River itself have lost their former carrying capacity to accommodate all excess water within its active domain due to over siltation and drainage congestion. So when the DVC dams are not able to regulate flood flow, then extreme rainfall of prolonged duration over the basin turns the normal situation into devastating flood, like the years of 1978 and 2000 in West Bengal. Identifying the existing problems of lower Damodar River, this paper principally tries to assess the potentiality of flood climate and to estimate the contributing rainfall-runoff, peak discharge, and existing carrying capacity of river in relation to increasing flood risk of lower basin using the quantitative hydrologic expressions.
Highlights
The flowing water finds the lowest parts of the earth’s surface, forming small rivulets that merge into larger ones and eventually find their way into a river
When we look at the line graph of runoff (Figure 6), we have found that, after dam construction, the supply of runoff is decreased below 30 mm which is recommended as critical level for 7075 m3 s−1 peak discharge at Rhondia
Employing Gumbel’s distribution of extreme annual discharge values, we have found that 100 years of flood discharge will reach up to 11,322 m3 s−1 in post-dam period, but the flood of that magnitude is associated with 5 years of recurrence interval in pre-dam period
Summary
The flowing water finds the lowest parts of the earth’s surface, forming small rivulets that merge into larger ones and eventually find their way into a river. “Flood” means that the flow in the river is in such an excess as to raise the level of the river at places so that it overflows the banks and rises to a level higher than the adjacent countrysides, inundating the areas adjacent to the channel [3, 4]. The river fails at that time to transmit the excess flow keeping it within the confines of its bank heights. The term “flood climate” is probably introduced by Hayden (1988) who has developed a global classification of flood-producing climates based on the mean seasonal state of the atmosphere [5]. Hirschboeck (1988) introduces the discipline of “flood hydroclimatology” which gives focus of hydrometeorological-scale atmosphere activity, while, at the same time, seeking to place this activity within a broader spatial and temporal climatic perspective of flood [6].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
