- DEAR GROUP MEMBERS

Does any one knows a practical (direct/indirect) method to measure the

disharge of submarin spring(s) emerging from karst coastal aquifer. Can you

direct me to related papers/references. We used basin water budjet to estimate

the overall discharge but we are looking to more accurat methods.

Thanks...

M. Sibai

ACSAD - Thank you very much for the replies from Mark, Alan

and Sarda.

The pond I mentioned was modified from a natural

pond.It also receives inflow from its catchment

(300,000m2). The pond capacity 50,000m3 (not 5,000m3

as in my last email, I apologise).The maximum water

area is 1,000m2. This is an earth pond, not a tank.

There is no detailed data availabe about its

relationships between volume and depth,or

stage-storage curve, or stage-discharge curve etc.The

so-called spillway is very rough (about 10m wide,just

a lower spot around the pond bund). This is the only

spot where pond water coming out. And it is very hard

to access to measure its water height above the

spillway. There is no any water control or measurement

equipment available. It is not practically to measure

its outflow in the downstream or measure the inflow to

the pond.

Generally this situation (pond) is quite common in the

remote regions.

It is required to estimate the flowrate of the

overflow from the pond (assume the pond is full) for a

storm event. The unit for flowrate is l/s, or m3/s, or

m3/hr, not volume m3, or l, or ft3. The flowrate is

then used to estimate the pollutant's

concentration/loadings in the downstream after mixing

with downstream water as the pond is full of

wastewater.

I doubt the result from rational method as it is too

high (>100 l/s for an event 3.8 mm/hr (average

intensity for a 4 hr event). There is another pond

nearby has a proper spillway, and the water height

above the spillway can be measured (0.05m for 3.8 mm/h

event).I used Manning's formula to estimate the

flowate. The flowrate is under 50 l/s for this one

under same event, but this nearby pond and its

catchment are much big.

It will be good if I can estimate how long the verflow

will last. But at this stage, I focus on the peak or

average flowrate. I also focus on the "estimation" by

calculation, not measurement.

Thank you very much again.

Dan.

> Darmao <darmao@...> wrote:

_________________________________________________________

> Hi there,

>

> My question is regarding the estimation of overflow

> from a pond. The pond capacity is 5000m3, and its

> catchment is small.There is a spillway which is very

> informal, and a rainfall gauge nearby.

> I tried to use rational method to estimate the

> overflow, but the result is obvious wrong.It is not

> safe to measure the water height above the spillway.

>

> How to estimate the flowrate of overflow from the

> pond?

> Any easy way?

>

> Thank you very much

>

> Dan

>

>

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