The Siang valley is mostly populated by the Adi tribes people who have their own nature worshiping religion known as Donyi Polo which are the Adi names for the sun and the moon. In the upper reaches near the China border there are Pemba tribes who are Buddhists. The people are mostly farmers and hunters. They cultivate rice in terraced fields and live in bamboo and thatch houses on stilts. The thatch is skillfully made of Tok leaves that are weather resistant. These houses stay warm during winter and cool during summer.
Surprisingly, there is no measurement of the flow of the Siang at Gelling where it enters India even though there are flow measurement stations at Tuting, Yingkiang and Pasighat further downstream. Even so the flow measurements from these stations, which are classified data and so are not available to the general public, must clearly be showing that the flow of the Yarlung Tsangpo into India is miniscule compared to that of the Siang in India itself and even less if compared to that of the whole Brahmaputra basin.
The most important data from the measurement of the flow of all the rivers that are tributaries of the Brahamputra is that regarding their contribution to the flood flow of the Brahmaputra during the monsoons which has such a devastating effect annually. Given the steep slopes of the lower Himalayas and the huge deforestation that has taken place, heavy rains in the hilly catchments of the tributaries of the Brahmaputra are the main cause of floods. Thus, it is imperative that both natural and artificial recharge is drastically increased in the Arunachal hills for any worthwhile flood control to be possible. The challenge to implementing artificial recharge measures is the steepness of the slopes and the very sparse population in the area. Nevertheless, thought must be applied and solutions found for this problem. The higher costs involved in this will be compensated many times by the prevention of losses due to floods. Moreover, artificial recharge will ensure that there is a better flow during the lean season and so improve the possibilities of navigation and irrigation in the Brahmaputra valley much more than building dams and dredging will ever do.
The other side of the coin is the diminished lean season flow in the rivers. Whereas the Siang has a good lean season flow due to the snow melt in the Tibetan plateau and upper Himalayas, the other rivers have very low flows. Due to the huge monsoon flows these rivers have very wide beds stretching to a few kilometers in width but just after that they dry up substantially. The Lohit River has the longest road bridge across it at Sadiya measuring 9 kilometers in length while the Dibang River has the third longest at 6.2 kilometers. The Bogibeel bridge across the Brahmaputra has the second longest bridge at 6.4 kilometers. However, when we crossed these bridges on our return from the Siang valley we found the river beds to be mostly dry and in some places covered with vegetation with the water flowing in a small stream.
Arunachal Pradesh is inhabited by tribes and and strict rules that prevent people from outside the state from settling or doing business there have kept the place comparatively safe from the depredations of greed based modern development and trade. Those going in for work or tourism have to obtain an inner line permit which is given for only a fortnight and has to be renewed after that. Even then dam building has made its mark in the Subansiri river valley and may some day lay the Siang valley to waste due to the local political leadership being inclined towards it. An interesting thing that I noted was that Hindi has become the lingua franca of the state. Everywhere right up to the China border people speak Hindi and some of them speak very chaste Hindi with good diction and pronunciation. The day we reached Yingkiong there was a big public meeting of the Chief Minister and he was speaking in Hindi because his own tribal language would not be comprehended by the Adi tribes people in the audience!!!
Finally a word about the roads. While the road to Yingkiong is fairly good apart from the stretches where construction work is going on, thereafter, up to Tuting the road is atrocious. We could drive at a an average speed of 15 kilometers and hour and it took us 9 hours to cover the distance. This is indeed a pity because this road is strategically very important and there is heavy army traffic on it most of the time and also because a good road combined with good tourism infrastructure can really open up this beautiful valley which is now visited only by river rafting enthusiasts. However, it is necessary to build these roads so as to cling to the contours as much as possible because the steep slopes get destabilised by the road cutting. While going up on the first day our path up the left bank of the river was blocked by a section where a landslide had taken place and taken the road with it. We had to turn back and return to Pasighat to cross the bridge there and go up the right bank instead. On our return journey also we encountered a land slide but that held us up for only an hour or so. The land slides during the monsoons are even more severe and frequent.
Even though the road situation is poor, there is fairly good mobile connectivity in the towns and also along the route. The road condition delayed my schedule and so at Tuting I had to reschedule my return flight from Guwahati by a day. As there was good mobile connectivity in the town, I could call up the airline and reschedule my flight.
All in all the trip up the Siang turned out to be truly one off the beaten track. The author James Hilton in his novel "Lost Horizon" has written about a mystical valley called Shangri-La where people live harmoniously. The Siang valley comes close to that utopian ideal and the trip was for me the experience of a lifetime.