Zonal estimation of probable maximum precipitation rain depths over the Krishna basin in peninsular India

Figures & data

Table 1  Zones of the Krishna basin

Zone	Name of zone (sub-zone)	Area (km^2)
I	Bhima up to Ujjani	15 287.2
II	Nira up to confluence with Bhima	7 168.3
III	Krishna up to Almatti	33 156.6
IV	Malaprabha up to confluence with Krishna	11 304.9
V	Tungabhadra up to dam site	29 315.5
VI	Vedavati up to confluence with Tungabhadra	23 862.2
VII	Lower Krishna – Nagarjun Sagar Dam site up to falls in Bay of Bengal	39 001.8
VIII	Sina up to confluence with Bhima	12 287.6
IX	Central portion of the Krishna basin which includes -
	Bhima from Ujjani Dam to confluence with Krishna	35 838.6
	Part of Krishna from Almatti to confluence with Krishna (excluding Malaprabha)	10 546.9
	Tungabhadra from dam site to confluence with Krishna (excluding Vedavati)	18 582.4
	From confluence with Bhima to Srisailam	11 452.6
	Between Srisailam and Nagarjunsagar dam site	11 144.3
Total catchment area of the Krishna basin		258 948.9

Fig. 1 Orographic features and nine zones of the Krishna basin.

Fig. 2 Locations of rainfall and SRRG stations in and around the Krishna basin.

Fig. 3 Decadal distribution of severe rainstorms.

Fig. 4 Monthly frequency distribution of severe rainstorms.

Table 2  SPS and PMP design rain depths (cm) over zones I–VIII

Zones	Rainstorm	MMF	1-day		2-day		3-day
			SPS	PMP	SPS	PMP	SPS	PMP
I	10 July 1958	1.34	10.7	14.3	-	-	-	-
	1–3 August 1956	1.20	-	-	16.2 (2–3 Aug.)	19.4	19.6	23.5
II	6–8 November 1922	1.26	10.2 (7 Nov.)	12.9	15.6 (6–7 Nov.)	20.0	19.6	22.4
III	4–6 August 1914	1.32	14.9 (5 Aug.)	19.7	22.9 (5–6 Aug.)	30.2	26.3	34.7
IV	4–6 August 1914	1.32	9.4 (5 Aug.)	12.4	16.3 (5–6 Aug.)	22.0	17.5	23.1
V	16–18 November 1992	1.30	16.1 (17 Nov.)	20.9	21.0 (16–17 Nov.)	27.3	25.6	33.3
VI	17 August 1917	1.13	7.0	7.9	-	-	-
VII	14–16 May, 1972	1.15	-		9.0 (14–15 May)	10.3	11.3	13.0
	22–24 July 1989	1.23	13.7 (23 Jul.)	16.9	21.3 (23–24 Jul.)	26.2	22.4	27.5
VIII	14–16 June 1942	1.23	12.8 (14 Jun.)	15.7	15.5 (14–15 Jun.)	19.1	18.8	23.1

Fig. 5 Three-day isohyetal pattern of the 4–6 August 1914 rainstorm over zones III and IV.

Table 3  DAD statistics of three severe rainstorms that occurred over and near Zone IX of the Krishna basin

Rainstorm	Duration (date)	Centre	Point	Area (10^2 km^2)
				5	10	30	50	100	150	200	250	300	400	500
September 1949	1-day (22)	Muddebihal /	21.0	18.0	17.0	16.5	15.7	15.3	15.0	14.7	14.5	14.3	14.0	14.0
	2-day (21–22)	Bagewadi	31.0	28.7	28.0	27.0	26.5	25.7	25.0	24.5	24.0	23.3	22.7	22.0
	3-day (21–23)		33.0	31.5	30.7	30.0	29.3	28.5	28.0	27.2	26.7	25.6	24.9	24.4
September 1964	1-day (29)	Atmakur	25.0	22.6	21.5	20.7	20.4	20.0	19.0	18.2	17.4	16.5	15.5	14.5
	2-day (29–30)		44.0	33.5	31.0	28.2	27.0	24.8	23.7	22.7	21.7	21.0	19.5	19.0
	3-day (28–30)		62.0	50.0	45.0	41.0	38.0	33.7	31.5	29.7	28.5	26.7	25.0	24.0
July 1965	1-day (15)	Nizamsagar	51.0	40.0	34.0	28.0	23.0	20.0	17.0	16.0	15.3	14.7	13.7	13.0
	2-day (14–15)		54.0	43.5	38.0	31.3	27.0	23.0	21.3	19.8	19.3	19.0	18.3	18.0
	3-day (13–15)		60.0	48.5	43.0	35.5	30.7	27.0	24.8	22.7	23.0	22.0	21.0	20.5

Table 4  SPS and PMP rain depths of three severe rainstorms over Zone IX of the Krishna basin

Rainstorm period	Transposed SPS rain depth (cm)			MMF	PMP rain depth (cm)
	1-day	2-day	3-day		1-day	2-day	3-day
21–23/09/1949	9.9 (22/9)	16.8 (21–22/9)	19.3	1.13	11.2	19.0	21.8
28–30/09/1964	9.9 (29/9)	14.1 (29–30/9)	17.7	1.20	11.9	16.9	21.2
13–15/07/1965	8.8 (15/7)	12.8 (14–15/7)	14.5	1.30	11.4	16.6	18.9
Envelope PMP rain depths →					11.9	19.0	21.8

Fig. 6 One-day isohyetal pattern of the 29 September 1964 rainstorm (in situ) over the Krishna basin.

Fig. 7 Transposed isohyetal pattern of 1-day rainstorm of 29 September 1964 over Zone IX of the Krishna basin.

Table 5  Envelope average (percentage) time distribution values over the Krishna basin

Duration (h)	Rain spell duration
	24 h	48 h	72 h
1	24	18	16
3	42	31	26
6	57	43	35
9	67	51	42
12	76	58	48
15	82	63	52
18	89	68	56
21	95	72	60
24	100	76	63
27		80	67
30		84	70
33		87	73
36		90	76
39		93	78
42		96	81
45		98	83
48		100	85
51			87
54			89
57			91
60			93
63			95
66			97
69			99
72			100

Fig. 8 One-day grid-cell PMP for the Krishna basin.