CIVIL WORKS GUIDELINES FOR MICRO-HYDROPOWER IN NEPAL
147
c) Long term average discharges
MONTH
LONG TERM AVERAGE
January
DISCHARGE (M3/S)
3.88
February
3.30
March
3.00
April
3.17
May 4.37
June
15.17
July 43.86
August
52.45
September
40.07
October
17.59
November
8.06
December
5.24
Annual
16.68
example:
Q =mean July 0.02123.(330)°.(308.5+1)1.0093.(1500)0.2523
= 43.86 m3/s
A.3.2 MIP PROCEDURE
Estimating the hydrograph of mean monthly flows
MONTH
NON-DIMENSIONAL MEASURED FLOW
HYDROGRAPH
(M3/S)
January
2.71
February
1.88
March
1.38
April
1.00
2.8
May 1.88
June
3.13
July 13.54
August
25.00
September
20.83
October
10.42
November
5.00
December
3.75
PREDICTED APRIL FLOW PREDICTED HYDROGRAPH
(M3/S)
(M’/S)
2.71 x 2.8 = 7.59
5.26
3.86
2.8/1.00 = 2.8
2.80
5.26
8.76
37.91
70.00
58.32
29.18
14.00
10.50
A.3.3 RESULTS
1. The dry season mean monthly flows calculated by the WECS and MIP methods are presented in the table and figure below. WECS
shows a slightly higher figure than MIP for the month of April. By definition MIP shows the measured flow. Experience shows that
results obtained by WECS and MIP methods vary for different catchments and it may not be always true that MIP yields lower value
than WECS. It is worth mentioning that Salleri Chialsa mini-hydro scheme uses a design flow of 2.5 m3/s (Ref.6).