Determination of groundwater sustainable yield using a numerical modelling approach for the Table Mountain Group sandstone aquifer, Rawsonville, South Africa

Lin, Lixiang; Lin, Haili

Determination of groundwater sustainable yield using a numerical modelling approach for the Table Mountain Group sandstone aquifer, Rawsonville, South Africa | Détermination du rendement durable des eaux souterraines à l’aide d’une approche de modélisation numérique de l’aquifère gréseux de la formation Montagne de la Table, Rawsonville, Afrique du Sud Determinación del rendimiento sostenible del agua subterránea utilizando un enfoque de modelado numérico para el acuífero de areniscas del Table Mountain Group, Rawsonville, Sudáfrica 应用数值模拟方法多南非罗森威尔地区桌山群砂岩含水层的可持续产量的确定 Determinação do rendimento sustentável de águas subterrâneas usando uma abordagem de modelagem numérica para o aquífero de arenito do Grupo Table Mountain, Rawsonville, África do Sul

2019

Lin, Lixiang | Lin, Haili

Sustainable yield is defined as the amount of groundwater abstraction that can be maintained for an indefinite time without causing unacceptable environmental, economic and social consequences. It is usually determined by monitoring the water-table depth, without the need for costly pumping exercises and subsequent deterioration of the groundwater and ecological environment. Groundwater numerical modelling provides an effective way to determine the yield by analysing the responding water levels to various pumping scenarios. In this study, the natural flow system and flow with pumping scenarios were simulated using FEFLOW for the fractured-rock aquifer in Table Mountain Group, South Africa. Results for different pumping rates show the distinct impact of groundwater abstraction on hydraulic head, which indicates that long-term abstraction slowly increases the well drawdown, but it would stabilize at a level that is dependent on pumping rate and induced recharge. To estimate the aquifer sustainable yield, a relationship between simulated drawdown and pumping rate was established, namely an exponential function with parameters that may change value between sites. This empirical relation, derived from this site-specific study, provides an option for informed decision-making. The issue of how to sustainably abstract groundwater might rely on a compromise between the groundwater user and the governmental authority.

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