Systems thinking and modelling for sustainable water resources management and agricultural development in the Volta River Basin, West Africa

Abstract

It is well established that the conventional approaches to understanding and managing natural resource systems such as the traditional linear-reductionist and mechanistic approach founded on a positivistic understanding of science do not provide a sufficient framework for understanding the dynamic complexity and growing uncertainties inherent in most environmental systems. Dynamic complexity arises because such systems are: tightly coupled (components or drivers of the system interact with one another); governed by feedback; nonlinear; history dependent (making a choice precludes other options and determines the destiny); adaptive (decision rules change over time); counterintuitive (cause and effect are distant in time and space); and policy resistant. Despite the recognition of these complexities, there is still a lack of dynamic models that adequately integrate various physical, social, and economic factors and feedback processes that determine the current and future dynamics of most Social-ecological systems such as water resources management systems. There is, therefore, the need for an integrated system dynamics simulation model that adequately captures the non-linear interactions and feedback effects between the key system drivers to improve our understanding of the dynamic behaviour of water resource systems and evaluate the effects of different policy and management scenarios.The overall aim of this research was to develop computer-based integrated conceptual, dynamic and simulation models that can be used to support decision-making for sustainable water resources management and agricultural development in the Volta River Basin in West Africa. To this end, a systems-based/systems thinking approach was used as the theoretical framework. Systems dynamics approach grounded in the relativistic, holistic/pragmatist philosophical or methodological paradigm provided an appropriate modelling tool to capture the relationships between the key system variables and their dynamic behaviour over time. Overall, a three-tied research plan (mixed methods approach) was employed. A comprehensive literature review, structured expert judgement/surveys and interviews were used to explore and identify the key system drivers, factors, and processes that influence the sustainability of the river basin system. A participatory modelling approach was employed where the system expert stakeholders from academia, NGOs, government, and private consultants were engaged in developing an integrated qualitative conceptual model that described the causal systemic feedback processes operating between the biophysical, environmental, and socio-economic drivers of the system. Based on the conceptual model, a formal quantitative simulation model was then developed using a system dynamics simulation approach, allowing different policy scenarios and strategies to be identified and tested. Besides the baseline or business as usual scenario, three additional policy scenarios were designed and simulated to explore alternative futures, including investment in water infrastructure, an anticipation of water scarcity or dry conditions, and land or cropland expansion.The results of the conceptual model showed that the feedback structure of the Volta River Basin is governed by of 21 feedback loops comprising: 14 reinforcing (positive) feedback loops and seven balancing (negative) feedback loops, indicating the complexity and dynamics of the system. These feedback loops revolve around the issues available ground and surface water resources, climate variability and change, population growth, soil fertility, crop yield, and poverty level. These feedback loops were quantified and simulated over a 50-year period (2000-2050) to understand the dynamic behaviour of the system. The results of the BAU scenario showed that agricultural water demand, water availability, crop yields, and net farm income increased until a peak is reached in the mid-2030, after which they remain in a state of equilibrium for the rest of the simulation period. Besides the baseline model run or Business as Usual (BAU) scenario, three additional policy scenarios were designed and simulated to explore alternative futures, including the development of water infrastructure (Scenario1), land or cropland expansion (scenario 2), and water scarcity or dry conditions (worse case, Scenario 3). Results from simulating a range of policy scenarios indicate that development of water resource infrastructure (e.g., construction of additional reservoirs or dams) is the best policy scenario that can contribute to sustainable water resource management and agricultural development within the basin.Overall, the results of this study enabled a better understanding of the feedback structure and dynamics behaviour of the Volta River Basin water resource system under conditions of environmental and socio-economic change. Theoretically, the research contributes to the advancement of systems approach, including understanding interconnectivity and complexity, which until recently, has been dominated by the linear reductionist approaches. Practically, this research provides stakeholders and managers, from local farmers and NGOs, to policy makers with decision support tools in the form of an integrated conceptual and the simulation models for the sustainable management of water resource system at the basin scale. Methodologically, this is one of the few studies to apply systems thinking and system dynamics as a modelling tool to understand the dynamics of water resource management system in Africa, and, therefore, makes a significant contribution and sparks new research in this regard.