Kamala

The Kamala (Kamala Khola) is a central Tarai river of the Madhesh region of southeastern Nepal. It rises in the Churia (Siwalik) Range near Maithan, close to Sindhuligadhi in Sindhuli District, at an elevation of roughly 1,200 metres (3,900 ft). From these forested foothills the river flows generally southward, cutting through the Churia hills in a series of gorges before emerging onto the alluvial plains of the Tarai, where it spreads across a broad, shifting sandy bed typical of the sediment-laden rivers draining the Churia.

On the Tarai plain the Kamala forms part of the boundary between Siraha and Dhanusha districts, two of the historic districts of the Mithila region. Continuing south, it crosses the international border into India in the Madhubani district of Bihar, a short distance upstream of Jainagar, where a barrage diverts and regulates its flow for irrigation on the Indian side.

The river has a total length of about 328 km (204 mi). Of this, approximately 208 km lie within Nepal and the remaining 120 km within India. The Kamala belongs to the wider Ganges drainage; in its lower reaches in Bihar it joins the Kareh (a branch associated with the Bagmati) at Badlaghat in Khagaria district, and the combined stream flows into the Koshi nearby, linking the Kamala to the great Koshi-Ganges network of the eastern Gangetic plain.

The Kamala drains a catchment of roughly 7,232 square kilometres (2,792 sq mi) spanning the Churia foothills and the northern Tarai. Like most rivers sourced in the Churia rather than the high Himalaya, it is a rain-fed, monsoon-dominated system: discharge swells dramatically during the June-September monsoon and falls sharply in the dry season, when flows can become very low. The basin receives an average annual rainfall on the order of 1,018 millimetres (40.1 in), concentrated heavily in the summer monsoon.

The Kamala is fed by a number of tributaries that gather runoff from the Churia slopes and the upper Tarai. Among the principal tributaries are the Tao, Baijnath Khola, Mainawati, Dhauri, Soni, Balan, Trisula and Chadaha. Because the headwaters lie in the geologically fragile, easily eroded Churia hills, the river carries a heavy sediment load, which it deposits across its lower course and which contributes to frequent changes in channel position.

The combination of flashy monsoon peaks and a meagre dry-season base flow has long shaped both the hazards and the development proposals associated with the river. The strong seasonality of discharge is the central engineering problem that inter-basin diversion schemes seek to address, by transferring water from the more dependable, snow-and-glacier-influenced Sun Koshi into the Kamala during the lean non-monsoon months.

The Kamala is an important water source for agriculture in the Madhesh Tarai, a densely farmed region producing rice, wheat and other staples. Its waters, together with those of neighbouring rivers, sustain irrigation across Dhanusha, Siraha and adjoining districts, although the river's strong seasonality limits reliable supply outside the monsoon. On the Indian side, a barrage near Jainagar in Bihar regulates flows for irrigation in Madhubani district.

The flagship development proposal for the river is the Sunkoshi-Kamala Diversion Multipurpose Project, an inter-basin transfer designed to boost the Kamala's dry-season flow. As proposed, it involves a diversion dam roughly 49 metres high on the Sun Koshi and a diversion tunnel about 21.5 km long that would carry on the order of 72 cubic metres per second of water into the Kamala basin. The scheme also envisages hydropower generation alongside a large irrigation command area in the Tarai, and has appeared on the Nepali government's priority list of national-pride water projects.

Independently, a Kamala Multipurpose Project has been studied with a proposed hydropower component on the order of 30 MW. Together these proposals reflect the river's perceived potential to deliver year-round irrigation and modest hydropower to a populous but water-stressed part of the Tarai, although figures and designs have varied between feasibility studies and remain subject to revision.

The Kamala flows through the heart of Mithila, the historic cultural region centred on Janakpur (Janakpurdham) in Dhanusha District. In the Hindu tradition Janakpur is revered as the birthplace and home of Sita (also called Janaki), daughter of King Janak and consort of Lord Rama, and as the ancient capital of the Kingdom of Mithila described in the Ramayana. The Kamala is counted among the rivers associated with this sacred landscape, and the region's rivers feature in local pilgrimage and ritual life alongside the Janaki Temple and Janakpur's many sacred ponds.

The river basin is the homeland of Maithili-speaking communities and of the distinctive Mithila (Madhubani) folk-art tradition, painted chiefly by Maithili women and now recognised worldwide. Agricultural life, festivals and ritual practice in the Mithila Tarai are intimately tied to the seasonal rhythms of rivers such as the Kamala, which water the fields that underpin the region's economy and culture.

As with many South Asian rivers, the Kamala carries devotional associations for the communities along its banks, and it is woven into the broader sacred geography of Mithila that draws pilgrims to Janakpur from both Nepal and India, particularly during Ramayana-related festivals.

The Kamala is one of the most flood-prone rivers of the Nepali Tarai. Its catchment lies largely in the fragile Churia (Chure) hills, where deforestation, soil erosion and landslides feed enormous quantities of sediment into the channel. As this sediment is deposited downstream, the riverbed in the lowlands has risen over time, in places higher than the surrounding farmland, which increases the danger of overbank flooding and of the river abruptly shifting its course.

To contain these floods, extensive river-training works have been built. The Kamala River Training Project, carried out with Indian bilateral assistance, constructed flood dikes, spurs and bank-protection structures along the lower river, and further tens of kilometres of embankments have been raised in Dhanusha and Siraha using gabions, geo-bags, sandbags and bamboo/porcupine structures. Despite these efforts, embankments are regularly breached during heavy monsoon floods, displacing communities and inundating farmland; the conversion of fertile fields into sand and cobble deposits is a recurring consequence.

Climate change, intensifying monsoon extremes and continued degradation of the Chure watershed are widely identified as factors raising future flood risk in the basin, making catchment conservation, sediment management and community flood resilience central concerns for the Kamala. Major regional floods in the wider Bihar plains into which the Kamala drains underscore the scale of loss of life and property that flooding in this part of the Ganges basin can bring.