Extreme drought and a warm autumn have left water levels on the Mississippi exceptionally low for the time of year. This is causing problems for farmers who rely on the river as a travel route for the crops: 60% of US grain exports use the waterway to reach the Gulf coasts. The total economic loss is estimated to be about $20bn and, despite attempts to dredge the river, it remains worryingly low as the country enters an important month for grain transport. Meanwhile, this week, a depression in the Bay of Bengal, off the Indian coast, deepened into Tropical Cyclone Michuang, resulting in 19 deaths. The weather system brought heavy rain and strong winds to the states of Odisha, Andhra Pradesh and Tamil Nadu on Monday, with the latter two also experiencing powerful storm surgesBefore Michuang made landfall in Andhra Pradesh on Tuesday, Chennai, the capital of Tamil Nadu, had recorded about 240mm (9.4in) of rain, which was classified as an extremely heavy rainfall event by India’s meteorological department. After that, the disastrous combination of storm surges and high rainfall led to significant flooding, with the cost of disruption valued at 50.6bn rupees (£478m) by the country’s chief minister. The devastation also drew attention to the difficulties India’s largest cities could face dealing with the effects of “significant” weather amid widespread unchecked construction and poor urban planning. Areas of Chennai were, for example, built on swampy catchment areas of lakes, which considerably increased the risk of flooding. Significant flooding also occurred in Tanzania last weekend after the town of Katesh was hit by torrential rain on Saturday, killing 69 people. Many more sustained serious injuries after the heavy downpours triggered landslides that damaged homes, infrastructure and farmland. Other east African countries, including Ethiopia, Kenya and Somalia, have also been hit by widespread flooding recently, after the combined effects of the El Niño weather phenomenon and the changing climate have exacerbated flooding in the region this year.