Paradoxical Drought...

Palaeoclimatic evidence suggests with medium confidence that there have been megadroughts associated with the Asian monsoon system throughout the Holocene (AR5; Cook et al., 2010). Additionally, Levermann et al. (2009), defined the two stable states of the monsoon; wet or dry. Despite the increased frequencies of extreme precipitation events (Goswami et al., 2006) and models predicting an overall increase in precipitation (Turner and Annamalai, 2012), drought through monsoon failure and/or over-usage of water resources, remains a risk to the South Asian regions and thus is the focus today...

Figure 1 - During the dry months, lack of storage
facilities means many have to walk kilometres to
find clean water (Times of India; Image source).

The Paradox - Cherrapunji, Meghalaya state, India. This village holds the world record for the most rainfall in one calendar month - July 1861 at 9300 mm, and over a 12-month period - August 1860 to July 1861 at 26461 mm. The 40 year average (1973-2012) still puts the value at 11859.4 mm, with the majority falling Mar-Oct and no or nominal rainfall Nov-Feb (Indian Meteorological Department). Despite this, during Nov-Feb the region experiences acute drought (Figure 1). Locals point to large-scale deforestation for drying up local springs but the main issue, reminiscent of so many areas in South Asia, is the lack of water capture and storage facilities.

The Himalayan/Karakoram mountain ranges feed many of Asia's greatest rivers, supporting over a billion people, and are thus known as 'Asia's Water Towers' (The Economist). In GHGs, Aerosols and Cookfires, I mentioned the reduction in black carbon through utilisation of cleaner cookfires, as a saviour of the glaciers. This may have been a little optimistic! IPCC AR5, suggests that despite a few glaciers advancing, the majority are in retreat (High Mountain Asia = losses of 26 ± 12 Gt yr⁻¹). In addition to this the levels of snowfall cover also appear to be reducing (AR5). Immerzeel et al. (2010) note that the contribution of glacial melt to the discharge of the Indus and Ganges is at 40%, using the Normalised Melt Index. Thus, in the short term discharge values will increase. However in the long-term, unless any action is taken it could result in far reduced discharge rates and the rivers becoming even more seasonal, causing further reductions in water security (Immerzeel et al., 2010).

Figure 2 - Villagers crowing around a well to gather water during 
a drought in Natwarghad, Gujarat state, India (Source)

Approximately 85% of all India's freshwater is utilised for agriculture, with groundwater forming the backbone of the agricultural sector, accounting for 59% (35,372,000 hectares) of all irrigated land in 2005-06. Approximately 85% of the population rely upon groundwater for drinking, which combined with agricultural use, make India the largest global groundwater user at 230 km³/yr. Rains account for ~67% of annual groundwater recharge, thus drought can severely impact upon water security of the country (Tyagi et al., 2012; Figure 2). Furthermore, a recent article in National Geographic, shows the impact of agriculture upon the Indus river as it flows through Pakistan; the heavy demands placed upon it have caused a 90% reduction of water reaching the delta over the last 60 years, impacting upon biodiversity such as Indus River Dolphin and the delta human populations. As with India, additional stress through drought may be catastrophic.

Next up...putting this and Dark Clouds - Silver Linings into context...agriculture