Chapter 1: introduction

Table 6.6: In stream Flow regimens for fish, Wildlife, Recreation and Related Environmental Resources Based on the Modified Tennant Method (Kali Gandaki “A” EIA Study)

Description	Monthly Average Flow	Rating or Score
Flushing or Maximum	200%	100
Optimum Range	60-100%	100
Outstanding	40-59%	90
Excellent	30-39%	80
Good	20-29%	70
Fair or Degrading	10-19%	26-50
Poor or Minimum	10%	25
Severe Degradation	0-9%	0-20
Computation of Modified Tenant to Kabeli for fair and degrading EF
Fair or Degrading – Jan (m^3/s)	1.03 – 1.96	26-50
Fair or Degrading – Feb (m^3/s)	0.86 – 1.64	26-50
Fair or Degrading – Mar (m^3/s)	0.89 -1.69	26-50
Fair or Degrading – Apl. (m^3/s)	1.33 – 2.53	26-50
Fair or Degrading – May (m^3/s)	3.16 – 6.01	26-50
Fair or Degrading – Jun (m^3/s)	8.63 – 16.93	26-50
Fair or Degrading – Jul (m^3/s)	16.90 – 32.10	26-50
Fair or Degrading – Aug (m^3/s)	18.17 – 34.52	26-50
Fair or Degrading – Sept. (m^3/s)	12.74 – 24.21	26-50
Fair or Degrading – Oct. (m^3/s)	5.81 – 11.04	26-50
Fair or Degrading – Nov. (m^3/s)	2.53 – 4.80	26-50
Fair or Degrading – Dec (m^3/s)	1.62 – 3.07	26-50

The modified Tenant Method in Kali Gandaki “A” and Middle Marsyangdi project for EF estimation used the minimum threshold flow of the driest month to maintain the riverine ecology to fair or degrading levelbut without analysing the ecological requirements of the targeted fish species to sustain the juveniles in the affected river stretch. This approach lead a number of unresolved questions against the modified Tenant method applied in these projects.

For the KAHEP, EF estimation of the modified Tenant method applied was cross-checked with the ecological requirements of the Target fish species of the river. To analyze required minimum environmental conditions of the target fish species juvenile in the affected stretch, hydraulic rating curve method is examined in conjunction with the physical habitat simulation model (PHABSIM) of the In stream Flow Incremental Methodologies (IFIM).

‘Hydraulic rating’ (also known as habitat retention) methodologies use changes in simple hydraulic variables, such as wetted perimeter or maximum depth, usually measured across single or multiple limiting river cross-sections (e.g. riffles), as a surrogate for habitat factors known or assumed to be limiting to target biota (Lohar et.al 1986). The implicit assumption is; ensuring some threshold value of the selected hydraulic parameter at altered flows will maintain the biota and/or ecosystem integrity. For the evaluation of ecological conditions 29 cross section of the affected dewatered stretch (from dam to the confluence with Tamor) were examined for the 10 per cent of the average monthly flow of the driest month February as EF. Table 6.7 presents the status of hydraulic variables in the Kabeli dewatered stretch river cross-sections.

Table 6.7: Hydraulic Variables in the Dewatered Stretch at 10% discharge of the Average Monthly Flow of February as EF

SN	Location	Chainage	Water depth (m)	Discharge (m^3/S)	Top waterway width (m)	Velocity (m/s)
1	Dam axis	0+0	1.14	0.86	0.63	2.39
2		0+200	0.71	0.86	16.98	0.14
3		0+400	0.68	0.86	20.96	0.12
4		0+600	0.63	0.86	14.29	0.19
5		0+800	0.34	0.86	6.64	0.76
6		1+0	0.37	0.86	3.45	1.36
7	Sarki Kholsi	1+200	3.58	0.882	51.715	0.01
8		1+400	0.58	0.882	39.823	0.08
9	Andheri Khola	1+600	0.56	0.907	34.751	0.09
10		1+800	0.52	0.907	20.646	0.17
11		2+0	0.18	0.907	10.419	0.96
12		2+200	0.72	0.907	18.378	0.14
13	Shiva Mandir	2+400	0.69	0.907	20.517	0.13
14		2+600	0.63	0.907	15.728	0.18
15		2+800	0.42	0.907	7.6	0.57
16	Kabeli Bazar and Khahare Khola	3+0	0.24	1.04	16.688	0.84
17	Sirupa Ghat	3+200	0.31	1.04	6.953	0.97
18		3+400	0.36	1.04	6.147	0.93
19		3+600	0.4	1.04	4.572	1.14
20		3+800	0.6	1.04	2.859	1.21
21		4+0	0.18	1.04	13.334	0.95
22		4+200	0.73	1.04	31.795	0.09
23		4+400	0.7	1.04	18.691	0.16
24		4+600	0.64	1.04	18.218	0.18
25		4+800	0.6	1.04	37.461	0.09
26		5+0	0.56	1.04	22.454	0.16
27		5+200	0.28	1.04	6.33	1.18
28		5+400	0.75	1.04	3.434	0.81
29	Tamor confluence	5+600	0.35	1.04	5.749	1.03

Source: KEL, 2011

The observed hydraulic variables (surrogates of the fishery habitats) were then cross –checked with the IFIM established values elsewhere in the region.

Determining habitat conditions using the IFIM method requires very intensive data and needs duration of 2-5 years for its assessment (World Bank 2003) which is not possible in present context. Therefore, habitat conditions established by the IFIM for comparable fish assemblage with Kabeli River are used for the assessment purpose. The IFIM assessment in the Western Ghat (Arunachalam M, 2000) has fish assemblages comparable to the Kabeli River. Table 6.8 presents the habitat requirements in the Western Ghat for the comparable fish species of the Kabeli River.

Table- 6.8: Flow condition and habitat suitability for fishes

	Depth used		Velocity used		Related species in Kabeli
Species at WB	Depth (m)	His	Velocity (m/S)	HSI	Species	Migratory status
Barilius bendelisis (India)	0.32 - 0.42	0.4 - 0.5	0.13 – 0.28	1.0 – 0.55	Barilius bendelisis, Barilius barila, Barilius shacra, Barilius vagra	Residence
Puntius ticto (India)	0.14 – 0.4	0.2 – 1.0	0.03 – 0.11	0.3 – 1.0	Puntius ticto, Puntius conchonius	Resident
Garra mullya (India)	0.16 – 0.32	0.21 – 1.0	0.03 – 0.13	0.21 – 1.0	Garra annandalei, Garra gotyla gotyla	Resident
Labeo calbasu (India)	0.25 – 0.49	0.15 – 0.8	0.05 – 0.09	0.5 – 1.0	Labeo dero, Labeo angra	Mid-range
Tor khudree (India)	0.16 – 0.32	0.21 – 1.0	0.03 – 0.13	0.21 – 1.0	Tor tor, Tor putitora	Long-range
Salmo trutta (Brown trout) (Europe)	0.10 – 0.70		0.18 – 0.90	Moderate	Snow trout (Schizothoraichthys progastus, Schizothorax plagiostomus, Schizothorax richardsoni, Schizothorax sinuatus)	Mid-range