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Environmental flows -
does it make sense for Mozambique?
Pieter van der Zaag
Professor of Water Resources Management
UNESCO-IHE Institute for Water Education
9 July 2011
Overview 1. Environmental flows - legal instruments
2. Incomati: the potential benefits of environmental flows
3. Zambezi: are environmental flows too expensive?
4. Conclusion
Política de Água (2007)
ÁGUA E O AMBIENTE (Cap. 4):
‘O uso e fornecimento de água para a preservação e manutenção dos ecossistemas deverá ser parte integral da gestão global dos recursos hídricos.
... a gestão dos recursos hídricos inclui a garantia de caudais ecológicos nos rios e estuários onde armazenamentos ou outros factores alterem o regime de escoamento ...’
Environmental flows - legal instruments
The SADC Protocol on Shared Watercourses (2000)
Introduces the concept of “Environmental use” = water for the preservation and maintenance of ecosystems
Protection and preservation of the aquatic environment (Art. 4, 2d):
‘State Parties shall ... take all measures ... to protect and preserve the aquatic environment, including estuaries, taking into account generally accepted international rules and standards.’
Environmental flows - legal instruments
Incomati
Interim Inco-Maputo Agreement (2002)
Article 6 Protection of the Environment (1) The Parties shall, individually and, where appropriate, jointly,
protect and preserve the aquatic environment of the Incomati and Maputo watercourses, taking into account generally accepted international rules and standards.
(2) The Parties shall, individually and, where appropriate, jointly, take
all measures to protect and preserve the ecosystems of the Incomati and Maputo watercourses.
1961 1971 1979 1988 2002
Incomati
2015?
0
50
100
150
200
250
300
350
400
450
500
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
disc
harg
e (M
m3/
mon
th)
Oct 1952 - Sep 1979 (average 2,297 Mm3/a)
Oct 1979 - Sep 1999 (average 950 Mm3/a)
050
100150200250300350400450500
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Month
Dis
char
ge (M
m^3
/mon
th)
2 yrs return period (1957-1980) 2 yrs return period (1980-2001)
0200
400600
800
1000
1200
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Month
Dis
cha
rge
(M
m^3
/mo
nth
)
5 yrs return period (1957-1980) 5 yrs return period (1980-2001)
Incomati Incomati
The flow regime has been fundamentally changed
Source: Carmo Vaz & Van der Zaag, 2002
Incomati estuary
Maputo city
Benguela island
1984 2003 Mangroves non degraded
Mangroves degraded
Dune vegetation Source: LeMarie et al., 2006
Incomati
Photoos: Sengo, 2003
Incomati
South Africa
“The Reserve”
basic human needs
environmental requirements
available for productive uses
Incomati
South Africa
“The Reserve”
basic human needs
environmental requirements
available for productive uses
dry year
Incomati
Thus:
Environmental flows are good for the Incomati in Mozambique
Zambezi
Zambezi
Source: Riversadale, 2011
A significantly modified flow regime
Zambezi
Source: Hoguane, n.d.
0
10
20
30
40
50
60
70
80
90
100
1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000
Year
Kg/
hour
Evolution of the catch rates of the shrimp in Sofala Bank
Zambezi
Source: Beilfuss and Brown, 2006 Re-establishing partly the flow regime - legally mandatory? - possible? - benefits? - costs?
Zambezi
Zambezi
Electricity produced: Full development: 30.8 TWh/yr EF1 scenario: -1.8 TWh/yr ≈ -145 Million US$/yr EF2 scenario: -0.4 TWh/yr ≈ -32 Million US$/yr
Source: Tilmant et al., 2010
Zambezi
Zambezi Environmental flows
- ZamCom does not yet prescribe EFR
- technically possible
- will benefit fisheries, and environment
- economic benefits not known (+20% fish production? Hoguane, unpub.)
- transboundary synchronisation of the operation of Kariba and HCB will bring additional benefits
- costs: reduced electricity production
- costs: may impair navigation, especially during the (short) low flow season
Conclusion
1. Environmental flows are good for Mozambique in the Incomati
2. Environmental flows are good for fisheries and the environment in the Zambezi
3. Environmental flows reduce electricity production and may impair navigation during one month per year in the Zambezi
4. Environmental flows in the Zambezi requires changing the operating rules of HCB
5. Who will decide?
