Nepali Times
Bunds, dams and lies

A barrage built by India on the Rapti River near the border at Laxmanpur that has inundated parts of the western tarai raised hackles in Kathmandu last week, poisoning the atmosphere before the Prime Minister\'s India visit.

A Nepali parliamentary committee report demanded that the afflux bunds leading to the barrage be knocked down. Less than 24 hours later, the Indian Embassy responded with a press release refuting every point in the report.

Nepal: The flood protection embankments and afflux bunds are too close to the border, within 300 m and 650 m from two border pillars. India: The right afflux bund is located well within Indian territory...(and) the alignment of the afflux bund is more than Lacey\'s Perimeter (see box) at every place, (The barrage and the embankment are not interlinked, although there are eight Nepali villages located between the embankment and the Rapti River.) Nepal: The embankments obstruct natural drainage from high ground towards the lower reaches. India: Admits this in the case of a local drain at Santaliya, but says a "toe drain" is under construction. Nepal: The Laxmanpur Barrage, of which the bunds are part, has been built within 5 km of the border. India: It is 8 km away and that the submergence it causes is within Indian territory, Nepal: The barrage has constricted the flow of the Rapti River to 284 metres at the border, leading to back-flows. India: The barrage is a structure for diverting non-monsoon flows and not a storage reservoir. Since the barrage is not yet operational, the question of submergence does not arise. Nepal: These points were raised at the Standing Committee on Inundation. Problems (SCIP), but they were ignored by India.
India: All queries raised by the Nepali side have been responded to.
Inundation in Nepal is not the result of anything India has built.Nepal: Inundation has affected 2,579 households, or 15,174 people, and about 3.900 hectares of land is now under water.

The Indian Embassy statement then moved on to another river, the Mahakali, where it says Nepal is building a 19.5-km embankment without "concurrence" of the Indian government. It says "the embankment constructed so far is, at many places, very close to the river bank, if not on the river bank itself".

It adds: "Due to the construction of this embankment, there has been disturbance in the river regime in its downstream reaches in Indian territory."

There has been no response from Nepal on this so far, although the Nepali embankments on the Mahakali (Sarada, in India) are being built to protect Nepali villages which happen to be on the other side of the river.

The issue of the flooding of these villages goes back to a possible shift in river course in 1920 after India built the Sarada Barrage to protect the Banbasa power house, say Nepali experts. In any case, comparing Rapti to Sarada is like comparing apples and oranges, they say.
P=2.67 VQ

If there is one example of where geopolitics and empirical hydrology meet, it is in the Indian Embassy\'s press statement on Laxmanpur. Nepali Times has got the following explanation for Lacey\'s Perimeter.

Lacey\'s Perimeter is P=2.67 vQ It is based on a constant coefficient design equation to approximately define cross-sectional shape of alluvial streams at dominant discharge. Lacey developed this method on Indian canals in the Punjab during the colonial era based on data characterised by narrow range of sediment transport rates, exclusion of bed material transport, and sediment size.

It is not applicable to all stages of river flow, and also neglects the importance of the nature of bed and sides of channels. The Froude Number, a dimensionless parameter influencing open channel flow, is affected by sediment concentration, bed material size and Manning Rugosity Coefficient \'N\'. But these are not included in the concept of Lacey\'s Perimeter pointing to its severe limitation.

(11 JAN 2013 - 17 JAN 2013)