So, What are the Implications of this Decrease in Surface Runoff?

Any projected decrease in surface runoff and water resources in general as a result of climate change will have huge implications for future agricultural, industrial and domestic water use. The domestic implications can clearly be seen in the previous case study of Polokwane, South Africa. The urgent need to reduce future water demand in the town means that the authorities are having to discourage any improvement of the water infrastructure (Cullis et al 2011). Even though the technology is there, there is currently no provision indoor taps throughout the town, meaning that most residents get their water from community taps which has the intentional effect of preventing increases in water demand. Naturally, this has significant knock on effects for domestic and industrial water use respectively, not only for the populations in terms of their standard of living, but it also effects the towns industry and economic growth.

Agriculture accounts for approximately 83.1% of total water water withdrawals, therefore it is extremely important to understand how changes in precipitation and evapotranspiration will effect food security in Africa. Rainfed crops such as maize make up a large proportion Africa’s agriculture (Giordano 2006), making Africa’s food security extremely vulnerable to climate change (Desanker 2002). This is also made worse by the fact that one third of Africa’s total income is derived from agriculture (Desanker 2002), therefore significant changes to crop yield will have considerable effects for Africa’s economy and future growth. The IPCC Fifth Assessment (2014) reaffirms this statement and goes on to say that Sub-Saharan Africa is expected to experience maize yield losses of around 22%, with some countries such as Zimbabwe experiencing losses of up to 30%.

The strain that changes in evapotranspiration and precipitation will have on the consistency and reliability of crops is an important issue in itself, however when projected population change is taken into account, the situation looks a lot more alarming. According to Gerland et al (2014), by 2050 Sub-Saharan Africa’s population is expected to have dramatically increased to 2.5 billion people, more than double of what it is today. The strain that this exponential population increase coupled with more variable water resources will place huge pressure on water resources. It is therefore crucial to deliver a sustainable solution that will help ensure Africa’s future crop yield and food security, along with industrial and domestic water needs