The Droughts are Coming...

Droughts are among the most costly natural disasters, affecting agriculture, ecosystems and societies. A study found that climate change has been impacting drought risk in the world since 1900. All the models are projecting that one should see unprecedented drying soon, in a lot of places.

Although it is floods that grab the headlines and trigger aid quickly, droughts have “shockingly large and often hidden” impacts that can last for generations, the world bank said in a report.

Girls in rural Africa born during a severe drought are more likely to grow up poor and hungry, be less educated, stunted, wed younger, give birth to underweight babies and bear more of them, the bank said.

This is an example of a poverty trap that has been created by a single episode of drought … and it continues across generations.

Nor are cities – the economic engines of most countries – immune from drought. The economic impact of droughts on city businesses is four times worse than that of floods.

Urban economies slow because of power outages, weak sales and increased health problems such as diarrhoea and dysentery.

Large swathes of eastern Australia have been in drought for periods ranging from a year to seven years.

Australia's biggest city Sydney is running down its water supply at the fastest rate on record. The amount of water flowing into the dam was just 10% of what it was a year ago. Catchments that have been historically reliable are now facing a critical shortage of water. A recent survey of Sydney residents found that despite the dry conditions and declining water supply, 47% of people did not realise there was a drought.

Reconstruction challenges after a disaster..

While the number of geophysical disasters – earthquakes, tsunamis and volcanic eruptions – has remained steady, the number of hydro-meteorological (weather-related) events – including droughts, windstorms and floods – has more than doubled since 1996.

• Whatever the kind of disaster, richer countries can guard themselves against it, much better : the 6.5 earthquake which hit central California in 2003 took two lives and injured 40 people. By comparison, the 6.6 earthquake, which hit Iran four days later, killed over 40,000 people. Both events took place in areas with high density populations

• In San Francisco….the last major earthquake caused the death of 62 people. In Turkey, an earthquake of similar magnitude killed 17,000.

•  Each year of the past decade an average of 258 million people have suffered from disaster – most of them in the developing world, up from 74 million a year in the 1970s...

A 2006 study of past disasters found that the immediate humanitarian relief work was generally effective and well-funded. But the same could not be said for the medium/long-term recovery and reconstruction. There tended to be a lack of funding and absence of coordinated management of the reconstruction phase following major disasters.

Despite huge improvements in the emergency response to natural disasters, permanent reconstruction is often inefficiently managed, uncoordinated and slow to get off the ground.

While humanitarian emergency operations have been in general well funded…sectors such as critical infrastructure/ environment, shelter/non-food items, restoration of livelihoods, agriculture and capacity building remain under funded.

Traumatised disaster survivors spend far too long in unsatisfactory transitional accommodation, often unsure whether they will ever have a permanent home and, if so, where. 

Anatomy of a disaster

The Kobe Earthquake 1995 : Most of the deaths and injuries occurred when older wood-frame houses with heavy clay tile roofs collapsed. The collapse of buildings was followed by the ignition of over 300 fires within minutes of the earthquake. The fires were caused by ruptured gas lines. Response to the fires was hindered by the failure of the water supply system and the disruption of the traffic system.

Weathering the storms in Cuba : Cuba’s geographical location gives it a high and recurrent risk of hurricanes. In the seven years between 1996 and 2002, six major hurricanes have hit Cuba, yet a total of only 16 people have died. The same hurricanes claimed the lives of 665 people elsewhere. 

Cuba is a small and poor country that makes the best use of its social assets at the national and local level. ‘Disaster mitigation, preparedness, response and recovery measures are enshrined in laws that are enforced’

The Indus Valley Civilization did not flourish by the Saraswati...

Analysis of the sediments on the river bed and satellite imagery showed recently that the majority of the Indus civilizational sites were grouped around the Ghaggar-Hakra rivers which are monsoonal rivers and not perennial ones. Via checkdams and storage sites, the cities stored water for use in the non-monsoon seasons. By not being near perennial rivers, these settlements avoided the destructive floods and change of channels that the mighty rivers are capable of.

Tall well, Mohenjo Daro / Nikesh Chawla / CC-BY-SA 4.0

A recent study showed that Indus urban settlements developed along an abandoned river valley rather than an active Himalayan river. This remnant of the inactive river is a former course of the Sutlej River. The flow of the Sutlej in this course terminated considerably earlier than the Indus occupation, with diversion to its present course completed 8000 years ago. This enabled long-term stability for Indus settlements sited along the inactive river.

Alluvial landscapes built by large perennial rivers form the environmental templates on which the earliest urban societies nucleated. On long time scales, rivers migrate by relatively abrupt changes in their course called avulsions. River avulsions have long been considered important in the development of early complex society. It is commonly accepted that settlements are clustered near active rivers and that river avulsion leads to settlement abandonment. 4500 years ago, the Indus Civilisation developed one of the most extensive urban cultures in the Old World (much more extensive than either the Egyptian or the Mesopotamian civilization). This civilisation was established on the alluvial plains of the Indo–Gangetic basin in northwestern India and Pakistan.

Lothal Dockyard / Raveesh Vyas / CC-BY-SA 2.0

The Indus Civilisation has long been considered river-based, with two of its largest and best-known cities, Harappa and Mohenjo-Daro, located adjacent to large perennial Himalayan rivers – the Ravi and the Indus, respectively. However, the largest concentration of Indus settlements is located near the divide between the Ganges–Yamuna and Indus river systems in India and Pakistan, far from major active rivers. There is an inactive river course around which these settlements are grouped which was thought to be the mythical river Saraswati. The drying up of the river that formed the Ghaggar–Hakra channel has been suggested as a major factor in the decline and abandonment of Indus urban centres in the region.

Analysis of the sediments on the river bed and satellite imagery showed that a major Himalayan river was not contemporaneous with Indus settlements in the Ghaggar–Hakra region and did not sustain the Indus Civilisation in this region. The locus for the abundant Indus Civilisation urban settlements along the Ghaggar–Hakra channel was the relict, underfilled topography of a recently abandoned valley of the Himalayan Sutlej River rather than an active Himalayan river. This abandoned incised valley was an ideal site for urban development because of its relative stability compared to Himalayan river channel belts that regularly experience devastating floods and lateral channel migration.

Water canal for the Great Bath,
Mohenjo Daro / Quratulain
CC-BY-SA 3.0

The abandoned river channel became fed by sedminents from ephemeral monsoon-fed rivers derived from the Himalayan foothills, likely the equivalent of the modern Ghaggar River and its tributaries. Indus urban settlements in the region were thus likely sustained by monsoons. This and the potential to pond flood waters in the topographic depression formed by the valley likely offered favourable conditions that led Indus populations to preferentially settle along the incised palaeovalley. A study suggested that decline in monsoonal rivers due to weakening of the Indian summer monsoon was responsible for the decline in the civilization.

River dynamics controlled the distribution of Indus sites in the region, but in the opposite sense to that usually assumed: it was the departure of the river, rather than its arrival, that triggered the growth of Indus urban settlements here. A stable abandoned valley, still able to serve as a water source but without the risk of devastating floods, is a viable alternative model for how rivers can nucleate the development of ancient urban settlements.

Acknowledgment : This post is entirely based on and edited from the article : 

Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements.