Development of a research approach to quantify temporal variations in baseflow in the developing world : application to Malawi

  • Laura Kelly

Student thesis: Doctoral Thesis

Abstract

Quantification of temporal variations in baseflow is crucial for sustainable water resources management. Unfortunately, in the developing world, many countries struggle to quantify baseflow due to challenges such as lack of data, sporadic data, and limited financial resources. There is also no systematic approach to guide those on how to overcome these challenges. For this reason, this research aimed to develop an approach to quantify temporal variation in baseflow in the developing world context. Malawi in Southern Africa was selected as the study area to develop the approach. Stakeholder engagement with the Government of Malawi was conducted to verify the need for the research and ensure the practical application of the research outputs. Existing data were collected and included climate data, river flows, lake levels and groundwater levels. Four case studies were used to demonstrate and test the selected methods and approach. First, Lake Malawi was used to demonstrate how to potentially analyse the recession limb of lake levels to provide a proxy indicator of changes in baseflow over time. Second, the Bua Catchment was used to demonstrate how sporadic river data and baseflow separation could be used to determine the annual and seasonal baseflow index (BFI). The BFI represents the baseflow component of river flow and is often used as a proxy indicator for groundwater discharge to a river. Third, the approach presented in the Bua Catchment was upscaled to a larger internationally strategic catchment, the Shire River Basin. Finally, the approach was upscaled to the national scale across Malawi. The results of the Lake Malawi study showed variations occurred in the recession limb between 1900-2016 which were attributed to changes in baseflow in the lake catchment. The changes occurred in years which coincided with either extremely dry or wet conditions in Malawi (1916, 1942, 1948, 2012 and 2013).Whilst, the approach did not provide conclusive results, it highlighted the importance of baseflow to the lake in the context of sustainable water resources management for Malawi. Given the importance of the lake for water supply, further research was required outwith this thesis to quantify the volume of baseflow contribution to the lake from all inflow rivers and evaluate any variations over time. The results from the Bua Catchment, the Shire River Basin and the Malawi studies conclusively showed that the approach was successful when used on the single catchment scale up to the national scale. The approach overcame the challenges typical of the developing world by utilizing sporadic river flow data and free open source tools. Specifically, the approach allowed the determination of annual and seasonal BFI and identification of long-term trends in the BFI data for a total of 68 river gauges across Malawi.This included 6 river gauges assessed as part of the Bua Catchment study and 15 gauges assessed as part of the Shire River Basin study. The results generated new knowledge on the important role of groundwater in sustaining rivers flows across Malawi. This Malawi case study was the first national scale baseflow assessment for the country and data coverage ranged from 11-64 years. The results showed that baseflow in Malawi follows a seasonal pattern with minimal differences between the average annual and average wet season BFI (0.57 and 0.52 respectively). Generally, considerable increases were seen in the dry season BFI (0.97). This indicates that 57%, 52% and 97% of the total Malawi river flow is derived from groundwater in the annual, wet and dry season respectively. Long-term behavioural changes in BFI across all periods were also found. Annually, 10% showed an increasing trend and 16% showed a decreasing trend, which was comparable to the wet season results where 16% showed an increasing trend and 18% showed a decreasing trend. In contr
Date of Award4 Dec 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorRobert Kalin (Supervisor) & Doug Bertram (Supervisor)

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