The entire basin is above 3,500m, apart from the lower Rishi Gorge which descends to 2,100m. Nanda Devi West at 7,817m is the highest peak.

Comprises the catchment area of the Rishi Ganga, an eastern tributary of Dhauli Ganga which flows into the Alaknanda River at Joshimath. The area is a vast glacial basin, divided by a series of parallel, north-south oriented ridges. These rise up to the encircling mountain rim along which are about a dozen peaks above 6,400 m, the better known including Dunagiri (7,066m), Changbang (6,864m) and Nanda Devi East (7,434m). Nanda Devi West, India's second highest mountain, lies on a short ridge projecting into the basin and rises up from Nanda Devi East on the eastern rim. Trisul (7,120m), in the south-west, also lies inside the basin. The upper Rishi Valley, often referred to as the 'Inner Sanctuary', is fed by Changbang, North Rishi and North Nanda Devi glaciers to the north and by South Nanda Devi and South Rishi glaciers to the south of the Nanda Devi massif. There is an impressive gorge cutting through the Devistan-Rishikot ridge below the confluence of the North and South Rishi rivers. The Trisuli and Ramani glaciers are features of the lower Rishi Valley or 'Outer Sanctuary', below which the Rishi Ganga enters the narrow, steep-sided lower gorge. The greater part of the park falls within the Central Crystallines, a zone of young granites and metamorphic rocks. Along the northern edge is exposed the Tibetan-Tethys, consisting of sediments of sandstones, micaceous quartzite, limestones and shales. The Tethys sediments form Nanda Devi itself and many of the surrounding peaks, and display spectacular folding and thrusting, while mountains like Changbang are granite. The crystalline rocks of the Vaikrita Group and lower part of the Tethys sediments have been tentatively subdivided into four formations, namely: Lata, Ramani, Kharapatal and Martoli.

Being an inner Himalayan valley, Nanda Devi Basin enjoys a distinctive microclimate. Conditions are generally dry with low annual precipitation, but there is heavy rainfall during the monsoon, from late June to August. Prevailing mist and low cloud during the monsoon keeps the soil moist, hence the lusher vegetation than is usually characteristic of drier inner Himalayan valleys. The basin is snow-bound for about six months of the year, snow being deeper and at lower altitudes on the southern side than the northern.

Forests are restricted largely to the Rishi Gorge and are dominated by Fir (Abies pindrow), Rhododendron (Rhododendron campanulatum) and Birch (Betula utilis) up to about 3,350 m. Forming a broad belt between these and the alpine meadows is birch forest, with an understorey of rhododendron. Conditions are drier within the 'Inner Sanctuary', becoming almost xeric up the main Nanda Devi glaciers. Beyond Ramani, the vegetation switches from forest to dry alpine, with scrub Juniper (Juniperus pseudosabina) becoming the dominant cover within the 'Inner Sanctuary'. Juniper gives way altitudinally to grasses, prone mosses and lichens, and on riverine soils to annual herbs and Dwarf Willow (Salix spp). Woody vegetation extends along the sides of the main glaciers before changing gradually to squat alpines and lichens. A total of 312 species have been recorded and preserved in the herbarium of Botanical Survey of India. At least 17 of these are considered rare. Not included in this list is (Saussurea sudhanshui), newly described from the area. A total of 773 plantshas been reported from the proposed biosphere reserve. Some 620 species were recorded by the 1993 Nanda Devi Scientific and Ecological Expedition. Nationally threatened species recorded include Nardostachys grandiflora (I), Picroehiza kurrooa (V), Cypripedium elegans (R), C. himalaicum (R), Dioscorea deltoidea (V) and Allium stracheyi (V). Local populations use a total of 97 species, 17 for medicine, 55 as food plants, 15 as fodder, 16 for fuel, 5 for tools, 8 for house building, 2 fibres, 6 miscellaneous, and 11 for religious purposes.

The basin is renowned for the abundance of its ungulate populations, notably Bharal (Pseudois nayaur). Preliminary surveys suggest that Himalayan Musk Deer (Moschus chrysogaster), Mainland Serow (Capricornis sumatraensis) and Himalayan Tahr (Hemitragus jemlahicus) are also fairly common. The distribution of Goral (Nemorhaedus goral) does not appear to extend to within the basin, although the species does occur in the vicinity of the national park. Snow Leopard (Panthera uncia) while scarce is relatively ease to observe in this park. Other large carnivores are Common Leopard (Panthera pardus), Himalayan Black Bear (Selenarctos thibetanus) and Brown Bear (Ursus arctos), the existance of which has yet to be confirmed. The only primate present is Common Langur (Presbytis entellus) although Rhesus Macaque (Macaca mullata) has been sighted outside the park boundaries. Some 83 species are reported from the biosphere reserve.

A total of 114 bird species were recorded during the 1993 Nanda Devi Scientific and Ecological Expedition. Abundant species recorded during May-June include Crested Black Tit (Parus melanolophus), Yellow-bellied Fantail Flycatcher (Rhipidura hypoxantha), Orange-flanked Bush Robin (Erithacus cyanurus), Blue-fronted Redstart (Phoenicurus frontalis), Indian Tree Pipit (Anthus hodgsoni), Vinaceous-breasted Pipit (Anthus roseatus), Common Rosefinch (Carpodacus erythrinus), and Nutcracker (Nucifraga caryocatactes). Species richness was found to be highest in temperate forests, with a significant decline in richness as elevation increased. Some 546 species are reported from the proposed biosphere reserve.

There is a lack of systematic surveys on invertebrate fauna. 27 species of butterfly were recorded during May-June 1993, including Common Yellow Swallowtail (Papilo machaon), Common Blue Apollo (Parnassius hardwickei), Dark-clouded Yellow (Colias electo), Queen of Spain (Issoria Iathonia), and Indian Tortoiseshell (Aglais cashmirensis).

Nanda Devi, after Devi (meaning goddess), consort of Shiva, is a manifestation of Parvati and has been revered as a natural monument since ancient time. Hindus have deified the entire basin and every 12th year devotees have approached the foot of Trisul to worship Nanda Devi, the 'Blessed Goddess'. The local people are Bhotias, those of Lata Village being Tolchas.

The park is uninhabited but there are two small villages (Reni and Lata) on the north-western side. Local people used to bring more than 4,000 goats and sheep to Dharansi and Dibrugheta for grazing and derive an income from employment as porters and guides before the area was closed in 1983. The trek to Nanda Devi base camp is considered to be one of the toughest in the world and has attracted large numbers of mountaineers and trekkers from all over the world.

The area is reputedly one of the most spectacular wildernesses in the Himalayas. The basin is dominated by Nanda Devi, a natural monument and India's second highest peak, and drained by the Rishi Ganga which has cut for itself one of the finest gorges in the world. It supports a diverse flora, largely on account of the wide altitudinal range, and an interesting variety of large mammals, including a number of rare or threatened species. Unlike many other Himalayan areas, it is free from human settlement and has remained largely unspoilt due to its inaccessibility, particularly the forests of the lower Rishi Valley.

Traditionally, the alpine pastures around Dharansi and Dibrugheta were grazed by livestock from Lata Village until the establishment of the park in 1982. The 'Inner Sanctuary' remained unexplored until 1934, when it was opened up to mountaineering. As a result, hunting, collection of medicinal plants and other forms of exploitation ensued. This part of the Himalayas was subsequently closed to foreign visitors from 1945 to 1974. There followed a spate of mountaineering and trekking but, because of the considerable disturbance being caused to the environment, tourism was banned in 1983.

Nanda Devi was earmarked as one of several protected areas for inclusion under the Government of India's Project Snow Leopard, but this project has not materialized to date. It has been recommended that the Pindari and Sundadhunga valleys at the southern edge of the Nanda Devi massif be designated a sanctuary to protect their reportedly large and viable ungulate and pheasant populations.

Litter, felling of trees and even cultural vandalism caused by expeditions, along with the introduction of sheep and goats to the 'Inner Sanctuary', reached serious proportions prior to the closure of the park. The conclusion of the 1993 Nanda Devi Scientific and Ecological Expedition was that wildlife numbers are increasing and the ecosystem of the park shows signs of recovery since the park was closed. Poaching continues, with organized groups are thought to enter the park via Roint Peak to Deodi and from Dewal via Roopkund to Bethartoli. However, poaching levels are not thought to present a serious risk to the park.

The two routes of access into the 'Inner Basin' used to be kept open by expeditions but have not been maintained by the park authorities since the ban on tourism. A few of the wildlife staff have been trained at the Nehru Institute of Mountaineering, Uttarkashi, but they lack the necessary mountaineering equipment to keep routes open.

Divisional Forest Officer, Nanda Devi National Park, Joshimath, Chamoli District, Uttaranchal.