Geoscience Reference
In-Depth Information
Figure 4.5
The various options for restoring some dry season flow into the middle reaches of the Great Ruaha River,
downstream of the Usangu wetlands, in the Ruaha National Park. These include upstream (
) or tributary storage/
transfer (
-----
), improved irrigation methods or use of groundwater (
), or even engineering the flows through the
wetlands (
), to reduce evapotranspiration.
intermittent stream which enters the Great Ruaha
downstream of the wetlands. The transferred water
would not be subject to the evapotranspiration
losses that occur at present in the wetland. The
Ndembera could reliably provide between 0.5 to
1.0 m
3
s
−
1
during the driest months, which would
allow at least a minimal flow into the study area.
The cost would be a reduction of inflow to the
Ihefu wetland (part of the larger UsanguWetlands),
which would reduce the dry-season extent of the
wetted area by a few square kilometres. This is seen
as a reasonable short-term tradeoff, in relation to
the crisis condition in the river downstream of the
wetland.
To increase the efficiency of irrigation methods.
At present, the rice is flood-irrigated, a very
wasteful use of the available water. WWF-TCO
(2010) estimated that 50% of dry-season diversions
