Groundwater stable isotope profile of the Etosha National Park, Namibia

Edward S Riddell,Wilferd Versfeld,Martin Kosoana,Werner Kilian

doi:10.4102/koedoe.v58i1.1329

Abstract

The Etosha National Park (ENP) is a large protected area in northern Namibia. While the ENP has received a lot of research attention in terms of terrestrial ecosystem process understanding in recent decades, aquatic and hydrological research has to date been limited to a descriptive form. This study provides a baseline hydrological data set of the spatial representation of Oand H-isotope ratios in the groundwater at a park scale, with a focus on three water point types utilised by game, namely natural artesian and contact springs as well as artificial boreholes. The data are used to infer broad-scale hydrological process from groundwater recharge mechanisms dominated by direct rainfall recharge in the west of the ENP to evaporative controls on surface water recharge pathways in the east of the ENP close to Fishers Pan. The findings are used to recommend further targeted research and monitoring to aid management of water resources in the ENP.Conservation implications: The terrestrial ecosystem, particularly large game, are tightly coupled to the distribution of available surface water in the ENP, notably contact and artesian springs. Within the ENP there is a perceived desiccation of these springs. This study provides a baseline upon which more comprehensive studies should be undertaken to differentiate natural from anthropogenic causes for this phenomenon.

Highlights

The requisite holistic understanding of natural and social environments within and around protected areas includes determining the complexities and challenges of managing water in their terrestrial environment (González et al 2013)
The Etosha National Park (ENP) in north-central Namibia is a case in point
The ENP encompasses a biologically diverse semi-arid woodland savanna ecosystem, whose core is occupied by a large depression, the Etosha Pan

Summary

Introduction

The requisite holistic understanding of natural and social environments within and around protected areas includes determining the complexities and challenges of managing water in their terrestrial environment (González et al 2013). In the definition of Rodríguez-Iturbe and Porporato (2004), the ENP would be classified as a water-controlled ecosystem, because of its water scarcity and because of its intermittent and sometimes erratic availability It is for this reason and the fact that the spatio-temporal distribution of biota in ENP is tightly coupled to its water distribution (Auer 1997) that baseline hydrological studies are required to be undertaken within it. The hydrochemical sampling of the water points in ENP was conducted between 05 and 11 May 2013 and took the form of both a west-east and a south-north transect (Figure 1). A differential GPS reading was taken with Trimble GeoExplorer 3® to determine accurate elevations above the mean sea level (± 10 cm)

Results and discussion

A C - dry Ombika Halali 1 Agab Turnoff

Excess Contact

Conclusion