Cyperus species- Kashmir
Tall Cyperus species growing along Nagin lake in Kashmir. Kindly help in ID.
Pl. also check with images at Cyperus squarrosus L. 
It may be helpful to know what Stewart had recorded about Cyperus squarrosus.
He found it from what was the North-West Frontier Province through Swat & Hazara to Ladakh (so I have a special reason to familiarise myself with this species - it is the only member of the genus known here) also as common Kashmir incl. Lidderwat & Pahlgam, though Srinagar/the lakes are not specifically mentioned; 1200-2700m.
Unfortunately, I have a description of this species from Bhutan and Sikkim- here it is a dwarf plant to 15cm at most, typically on mossy boulders, damp roadsides, fields, arable weed. The herbarium specimens at Kew support these dimensions, so this species seems highly unlikely.
Have had a quick look at information about 5 Cyperus recorded from the lakes (all sounded promising) or nearby in Srinagar but 4 definitely do not fit; the other I cannot find an accepted name to check it out. Stewart knew it as C.globosus (syn. C.capillaris). Perhaps you can track down what its current name is and whether it is a possibility?
I am a complete beginner with Cyperus - we only have 2 species in UK and they are not common. Rather more to consider in the Himalaya/ India. Stewart lists close on 50 species from Pakistan & Kashmir....
Can be Cyperus cyperinus, need a specimen to confirm the identity.
I know very little about Cyperus but worth mentioning that Stewart did not record tis from anywhere in Pakistan or Kashmir, though did
say "To be expected in Jammu".