As well as Aqueduct's Water Risk Atlas; a really cool interactive map showing inter-annual variability, drought severity, flood occurrence etc across the globe.
Two maps I have picked out for you from the site are:
Drought severity, red areas are those that have the most extreme droughts:
Groundwater stress, which is the ratio of consumption to withdrawal, red areas indicate potentially unsustainable use of groundwater.
BUT we still need a bit of caution: when studying these maps it is important to take note of the source of the data. These maps are based on data from 1901 - 2008 and 1958 - 2000 respectively. Another two important things to be aware of when looking at groundwater stress is recharge was modelled, and we don't have the full picture concerning groundwater withdrawals and rates. We don't actually know how many wells there are and how much water is being abstracted, especially in developing countries.This point is illustrated in this news article from 2010 (also an interesting tidbit for all those Christmas dinners you are going to) about groundwater withdrawals in Siem Reap, Cambodia which are endangering the future of Angkor Wat.
On another groundwater note ....
I love the history and culture of past civilisations like the Maya, Incas and Khmer Empire. Why such societies 'disappeared' is intriguing; usually attributed to conflict and/or the introduction of disease from explorers - access to water during drought could have played a part. For the Maya, settlements in the north of Yucatá who had natural and easier access to groundwater stores were the ones that appear to have been abandoned last.... interesting eh..... but could drought be the main cause for the disappearance of the Maya.....hmmmmm...... what do you think?
Hey Alice, nice post. Do you know roughly how they come up with groundwater stress maps? going back to what you said that exact water resources and withdrawal are not known?
ReplyDeleteHi Honeyeh, I am sorry to has taken me so long to reply to your comment! I am really glad you asked this question. First off they calculate groundwater stress maps by comparing the ratio of groundwater footprint and aquifer area. If the ratio above 1 it is consider at a high risk of groundwater stress.
DeleteTo calculate groundwater footprint - which is the area needed to sustain current groundwater use. They model recharge rates, contribution of groundwater to surface water stores, areal extent of aquifer and groundwater abstraction rates. Exact water withdrawal rates aren't known and the authors use country reported statistics from : http://www.un-igrac.org. The uncertainty in this is recognized by the authors and they did a Monte Carlo simulation of 100
independent realizations for abstraction and recharge which returned 10,000 possible values for groundwater footprint of which they took an average. Hopefully I answered your question. Here is the paper if you would like to read in more detail: http://www.nature.com/nature/journal/v488/n7410/pdf/nature11295.pdf =)