2 research outputs found
Management of Alluvial Aquifers in Two Southern African Ephemeral Rivers: Implications for IWRM
27 pages, figures, and tables statistics.This paper summarises innovative research into the assessment of longterm groundwater recharge from flood events in dryland environments of the Kuiseb (Namibia) and the Buffels (South Africa) rivers. The integrated water resource management (IWRM) policies and institutions affecting the exploitation of groundwater
resources in each of these developing countries are compared. The relatively
large alluvial aquifer of the Kuiseb River (∼240 Mm3) is recharged from irregular
floods originating in the upper catchment. Reported abstraction of 4.6 Mm3 per year
is primarily consumed in the town of Walvis Bay, although the groundwater decay
(pumping and natural losses along the period 1983–2005) was estimated in 14.8 Mm3
per year. Recharge is variable, occurring in 11 out of 13 years in the middle Kuiseb
River, but only in 11 out of 28 years in the middle-lower reaches. In contrast, the
Buffels River has relatively minor alluvial aquifers (∼11 Mm3) and recharge sources
derive from both lateral subsurface flow and floodwater infiltration, the latter limited
to a recharge maximum of 1.3 Mm3 during floods occurring once every four years.
Current abstractions to supply the adjacent rural population and a few small-scale,
irrigated commercial farms are 0.15 Mm3 yr−1, well within the long-term sustainable
yield estimated to be 0.7 Mm3 yr−1. Since independence in 1990, Namibia’s water
resource management approach has focussed on ephemeral river basin management
of which the Kuiseb BasinManagement Committee (KBMC) is a model. Here, some
water points are managed independently by rural communities through committees
while the national bulk water supplier provides for Walvis BayMunicipality from the
lower aquifers. This provides a sense of local ownership through local participation
between government, NGOs and CBOs (community-based organisations) in the
planning and implementation of IWRM. Despite the potential for water resource
development in the lower Buffels River, the scope for implementingIWRMis limited
not only by the small aquifer size, but also because basin management in South
Africa is considered only in the context of perennial rivers. Since 2001, water service
delivery in the Buffels River catchment has become the responsibility of two newly
created local municipalities. As municipal government gains experience, skills and
capacity, its ability to respond to local needs related to water service delivery will be
accomplished through local participation in the design and implementation of annual
‘integrated development plans’. These two case studies demonstrate that a variety of
IWRM strategies in the drylands of developing countries are appropriate depending
on scales of governance, evolving policy frameworks, scales of need and limitations
inherent in the hydrological processes of groundwater resources.The study was funded by the 6th framework of the European Community
through the project “FloodWater recharge of alluvial Aquifers in Dryland Environments”, WADE
Project (contract no. GOCE-CT-2003-506680). Obbe Tuinenburg and the staff of Gobabeb Training
and Research Centre are gratefully thanked for their assistance.Peer reviewe