This blog aims to assess the impacts of intense
rainfall on water resources. According to the Clausius-Clapeyron
relation, as temperatures increase the moisture holding capacity of the
atmosphere will also increase (Owor et al 2009). This relationship is
exponential, hence with an increase of global temperatures by 2oC, a
warmer country such as Tanzania in Sub-Saharan Africa may be effected to a greater
degree, compared to a cooler country such as the UK (Figure 1). In
Sub-Saharan Africa it is expected, that precipitation will occur less
frequently but more intense, due to the holding capacity of moisture increasing
by 6.5%K-1 (Taylor et al 2012).
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Implications of intense
rainfall
The El Nino Southern Oscilation event (ENSO),
occurs once or twice per decade, this is an extreme event with intense
rainfall. During ENSO events in Makutapora, Tanzania, intense rainfall is
advantageous for the country, as most groundwater recharge occurs during this
event (Figure 2). Semi-arid and arid regions are heavily dependent on
groundwater as a freshwater resource, hence an increase in intense rainfall due
to climate change may be advantageous in Tanzania, creating more available
water for domestic and agricultural use (Taylor et al 2012). Additionally, the
increase in groundwater levels, may help reduce drought effects that may occur
during dry periods.
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Conversely, intense rainfall can be a disastrous
event as seen in West Africa (e.g. Niger, Sudan, Sahel). In many cases, floods
may occur, and crops are likely to wilt as they take vast amounts of water in a
short period of time. This could lead to a large decrease in crop
availability, leading to food shortages. During 2007, in Senegal, food
shortages, lead to famine, economic decline and some riots (Tschakert et al 2010). Additionally,
floods create stagnant water, resulting to diseases such as cholera and
malaria. Hence, the livelihood of people may deplete.
Thoughts:
It is suggested that intense rainfall may increase
groundwater recharge, thus replenishing the area. Conversely heavy rainfall can lead to
catastrophic events, where food decreases and economies may be severely
affected. Therefore it is essential, to
predict the negative impacts of intense rainfall for specific areas and try to prepare
in advance.
Can’t
wait to hear your thoughts!
I think the role of intensive rainfall in recharging active groundwater is very important. Considering its devastating effect through flooding etc, however, I fear that this can be a loss rather than benefit on human's life. I also wonder how we should assess the impact..like what kind of indicators to use (e.g. GDP/agricultural productivity/health etc). I am so looking forward to your upcoming posts Maria!
ReplyDeleteHey Satomi! Thanks for your comment! I agree, intensive rainfall should be mostly non-beneficial. However, I feel in many geology plays an important role. I like the idea of how we should assess the impacts, it is truly problematic, as it effects people in so many aspects of their life and they are all interrelated.
ReplyDeleteSatomi is correct that Intensive rainfall can be very destructive - damaging crops and eroding soil. Maria also has a good point that it is geologically dependent. I observed a 198mm rain event in Dubrovnik (karstic limestone geology) in 2014 and no flooding resulted. In another geological environment, this rain event would have been much more destructive.
ReplyDeleteNew paper due out in a few weeks adding more evidence of the intensive rainfall - groundwater recharge link in the tropics: Jasechko, S. and Taylor, R.G., in press. Intensive rainfall recharges tropical groundwaters. Environmental Research Letters
Hi Maria! I enjoyed reading your post a lot. Regarding the role of ENSO in intense precipitation and groundwater recharge, I was wondering if you'd heard about this year's predicted ENSO event - it's meant to be the biggest yet, even greater than the 1997/98 one! What are your thoughts on the impact this may have on African water resources, and adaptations/opportunities this may require/pose?
ReplyDeleteHey Shruti, Sorry for the late reply! Thank you for your comment. I suspect the impacts on African water resources will be an intensification of the 1997/98. Some areas will endure droughts whereas others will endure intense rainfall events. However, we cannot be sure, it is essential to assess the impacts.
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