Abstract
Demand for freshwater is rising with factors, such as population growth, land use change and climate variations, rendering water availability in the future uncertain. Groundwater resources are being increasingly exploited to meet this growing demand. The aim of this study is to identify the influence of population growth induced by land use change and climate change on the future state of freshwater resources of Lamu Island in Kenya where a major port facility is under construction. The results of this study show that the “no industrial development” population scenario (assuming the port was not constructed) would be expected to reach ~50,000 people by 2050, while the projected population upon completion is expected to reach 1.25 million in the same year when the Lamu Port-South Sudan-Ethiopia Transport Corridor Program (LAPSSET) port reaches its full cargo-handling capacity. The groundwater abstraction in 2009 was 0.06 m3 daily per capita, while the demand is expected to raise to 0.1 m3 by 2050 according to the “LAPSSET development” projection. The modelling results show that the Shela aquifer in Lamu, which is the main source of water on the island, will not experience stress by 2065 for the “no industrial development” population scenario, whereas for the “LAPSSET development projection” population scenario, it will occur sooner (between 2020 and 2028). The modelling results show that the Representative Concentration Pathways (RCP) climate change scenarios will have a smaller impact on the effective water volume reserves than Special Report on Emissions Scenarios (SRES) for the “no industrial development”, while the impact is expected to be similar for the “LAPSSET development”, suggesting that population growth exacerbated by land use change will be a more significant driving force than climate change in affecting freshwater availability.
Highlights
Freshwater is a scarce resource: only 2.5% of the total water volume on Earth is freshwater, with the largest portion of it lying underground [1]
The results of this study further show that the Representative Concentration Pathways (RCP) scenarios have lesser impacts on the aquifer size than the Special Report on Emission Scenarios (SRES), as demonstrated by overall larger freshwater volumes of the RCPs (Figures 5–15)
The results indicate that under the “no industrial development” scenario, the Shela aquifer would serve the residents of Lamu Island as a freshwater reservoir for longer before getting stressed by the overexploitation and subsequent salinization
Summary
Freshwater is a scarce resource: only 2.5% of the total water volume on Earth is freshwater, with the largest portion of it lying underground [1]. Urban uses currently account for an average of 10%–20% of the total water withdrawals in developing world basins, with demand increasing rapidly as a direct result of population growth in urban areas [10]. This can be attributed to the fact that most of the growth in the world’s population is taking place in urban areas in low and middle-income nations, and this is likely to continue [11]
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