What do Rivers have to do with Silt??


SANDRP

Rivers are again in the news, though so far only for symptomatic reasons. The new government at the centre has renamed the charge of water resources minister to Minister of Water Resources, River Development and Ganga Rejuvenation. There is fundamental contradiction within this name plate and we have in fact yet to see this nameplate.

There is also a lot of discussion about rejuvenation of Ganga, with the Prime Minister promising the people of Varanasi Parliamentary constituency that he will rejuvenate Ganga.  There is no clarity about how he plans to go about in achieving that. His claim during elections that Gujarat Government’s Sabarmati Riverfront Development provides a model for this is clearly a non-starter. Sabarmati has water only in 10.4 km of the river stretch that flows through Ahmedabad. If you go upstream of this stretch, you will find a dry river in most non-monsoon months and if you go downstream, you will…

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REMODELING OF EXISTING SPILLWAYS (PART 3)


REMODELING OF EXISTING SPILLWAYS (PART 3) By R.M.Khatsuria

Hydrotopics

Remodeling for ensuring structural safety

 

A necessity for remodeling to ensure structural safety may arise because

 

  • the dam is pretty old and turns out to be structurally unsafe according to present practice
  • increased inflow/outflow discharge requires a wider section of the spillway
  • additional loads are introduced following a major earthquake

 

In the above cases, hydrologic and hydraulic safety considerations are also involved together with structural safety that generally requires strengthening of the dam cross section with buttresses and other similar measures. However, for spillway, widening of the cross section is the only alternative available. In addition to ensuring a good bond between the old and the new construction, such a modification would have serious implications on the hydraulics of the spillway and energy dissipating arrangements. Figure 1 depicts a possible remodeling of an existing spillway by way of flattening of the rear slope for widening of…

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REMODELING OF EXISTING SPILLWAYS (Part 2)


REMODELING OF EXISTING SPILLWAYS (Part 2) BY R.M.Khatsuria

Hydrotopics

 

(For similar topics refer http://hydrotopics.wordpress.com)

 

R.M.Khatsuria

(email: rmkhatsuria@rediffmail.com

 

 

 (Want to refer Part 1?)

Remodeling for the purpose of increasing the storage of the reservoir involves raising of the reservoir level above the normal operating level and this would result in additional submergence of land in the upstream. In the case of ungated spillways, the normal operating level is at the crest level and there always is a temporary submergence caused by the overflow depth during the passage of floods. Thus, the full reservoir level (FRL) can be raised up to the maximum depth of overflow corresponding to the allowable limit of the upstream submergence. However, with the gated spillways, the FRL is required to be raised, which brings additional area under the submergence, beyond that corresponding to the original FRL. Thus, the remodeling is to be accomplished under the above mentioned pre-requisites.

When…

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