The splatter of raindrops is a constant backdrop. A ruffle-feathered pigeon, soaked and feeling sorry for itself, perches on a balcony rail. Cars and safa tempos slalom among the potholes, splashing people on foot when a wheel drops into muddy water. Mould spores seem to be the only thing that can dodge the raindrops. Shoes, clothes, car seat-covers all sport a fine, fuzzy skin and have to be rubbed periodically with disinfectant. Kathmandu nestles down under bleak cottony skies, somewhat like that pigeon on my office balcony. As the end of the monsoon approaches, we're well and truly tired of rain.

Mind you, there are worse places to be in the rainy season, many in India. Ask anyone who has ever lived in Calcutta. The sight of a Writers Building babu nonchalantly wading through waist deep floods across BBD Bag springs to mind. So does the less lugubrious picture of rats, swimming past several policemen trapped on a traffic platform in the centre of Chowringhee. Downstream from Nepal, in north Bihar, this is the dreadful time of year. In the Maithili-speaking heartland around Darbhanga, the waters of the Arun, the Sun Kosi and further west, the Bagmati, debouch onto natural flood plain. Huge embankments, built forty years ago to protect local farms, instead trap the waters. More than three million people own land that is underwater for nine months of the year.

Mandarins in Patna and Delhi murmur about deforestation in Nepal but they know that the late Jawaharlal Nehru's deification of science and technology are to blame. The embankments were built because the great man favoured mega-projects. No study was done of their effect, or the pattern of flooding in this silt-rich region between the Himalayas and the Ganges. Now the farmers of Darbhanga drive taxies in Delhi, sell fruit in Bhaktapur or pole boats past embankments where soaked shantytowns sit amid mosquitoes and waterborne disease. Bihar's water secretary once told me-with total seriousness-that she was suggesting that people take fish farming as an activity. A long campaign for compensation, run by the Inspector General of Police in Patna, who owns 26 flooded acres near Jaynagar, ebbs and flows but like the flood waters, seldom seems to go anywhere.

Then there is Bangladesh. The subcontinent's two greatest river, the Ganga and the Brahmaputra merge at Goalundo Ghat, one of the most remarkable places I have ever seen. I travelled there with the head of the Bangladesh Red Crescent. We drove until the road was washed out and hopped into a country boat to complete the journey. The Ghat was still a few hours away, through flooded fields and past inundated villages. Then suddenly you round a bend and your jaw drops in wonder. Huge ocean-going ships ply the river here, now called the Meghna. Our little wooden barge had to scuttle for cover as one leviathan steamed by us, hooting a warning from the bridge. An all water horizon makes you think you're offshore, out on the Bay of Bengal. But no, this is just forty km north of Dhaka, well inland on what the map says is just a river, flowing through villages and past places like Goalundo Ghat.

Here the problem is erosion. As you drift with the current, it's possible to see huge chunks of earth fall into the river, someone's land, gone for good. Villages become peripatetic in such circumstances. People shift back from the riverbank until they run into someone else's property. Then they go to the city to pedal a rickshaw or work in a garment sweatshop, stitching shirts for The Gap. Meanwhile, downstream the silt-laden waters deposit mounds of dirt and islands emerge from the flood. Within a few hours, a banana tree is planted, a paddy field is staked out and emerald green seedlings are shoved into the rich, alluvial muck.

As I sit high and relatively dry in my eyrie in Kathmandu, the rhythmic rain drops fall and start the long journey south. The life cycle is renewed; one family's misery is another's new hope. But I wish it would stop raining. My brain is getting mouldy.