Introduction to the SW/GW interaction programme of the AGW-Net

The Africa Groundwater Network has received funding from the Carnegie Corporation of New York through the Science Initiative Group’s (SIG) Regional Initiative in Science and Education (RISE) program (https://sig.ias.edu/rise). This grant is for the purpose of enabling sustainable research groups in Africa with the capacity to pursue collaborative projects that make unique and impactful contributions to the advancement of scientific and engineering knowledge.

The grant will contribute towards a new progamme within the AGW-Net which will focus on increasing the awareness of the importance of surface water and groundwater interactions in Africa.

The programmes specific aims include:

1.     Foster stronger links between surface water and groundwater hydrologists,

2.     Education and capacity building in the field of surface and groundwater interactions,

3.     Identify key research sites and potential funders to undertake large scale investigations into significant and regionally important sites with strong interactions between surface water and groundwater.

The funding will contribute towards a launch and workshop to be held during the annual meeting in 2017 which will bring together hydrologists and hydrogeologists to discuss key issues around the understanding of and modelling of SW/GW interactions. In addition, the funding will support the costs of preparation research proposals by AGW-Net network members who have identified funding opportunities in the area of SW/GW interactions.

Click this link for further details or contact Dr Jane Tanner.

Overview of surface and groundwater interactions

Groundwater and surface water interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. Groundwater and surface water interact in nearly all landscapes, ranging from small streams, lakes and wetlands to major river valleys and seacoasts. In many situations, surface water bodies gain water and solutes from groundwater systems and in others the surface water body is a source of groundwater recharge and causes changes in groundwater quality. As a result, withdrawal of water from streams can deplete groundwater or conversely, pumping of groundwater can deplete water in streams, lakes, or wetlands. Pollution of surface water can cause degradation of groundwater quality and conversely pollution of groundwater can degrade surface water. Thus, effective land and water management requires a clear understanding of the linkages between groundwater and surface water as it applies to any given hydrologic setting.

Traditionally, management of water resources has focused on surface water or groundwater as if they were separate entities. This has led to the disciplines of hydrology (surface water) and hydrogeology (groundwater) developing separately from each other and becoming quite isolated. As pressure on land and water resources increases, it is becoming ever more apparent that development of either of these resources affects the quantity and quality of the other and the consequences of not dealing with the hydrological system in an integrated manner are becoming more severe. In response to a greater awareness of a unitary and interdependent hydrological system, focus is shifting towards bringing surface and groundwater hydrologists together to increase our understanding of interactions. This has, however, been fraught with difficulty (due to different traditional assessment methods and levels of understanding) and in most cases the assessment of water resources remains separate.

Key areas of uncertainty

Terminology –Inconsistent use and misuse of terminology and over-simplification of hydrological processes have played a role in misunderstandings, e.g. the term baseflow has been used to represent the ‘low flow component of stream flow’ (which can be made up of various different sources of water) and also used to specifically represent the groundwater contribution to stream flow.

Spatial scales – Surface water catchment and aquifer boundaries don’t always coincide, which complicates integration especially when trying to represent the systems in an integrated manner in hydrological models.

Temporal scales – Typically groundwater moves at a much slower temporal scale than surface water which  complicates integration especially when trying to represent the systems in an integrated manner in hydrological models.

Integrated modelling – The types of models typically used by hydrologists and hydrogeologists differ significantly in terms of structure. While new developments in model flexibility and integration are promising, there remains much uncertainty around the representation of certain processes in models.