236
J. U. Kitheka et al.
Three major flood events have occurred in the recent past: 1961/1964, 1997/1998,
and 2003/2004. During floods, the entirety of the Kano Plains is usually inundated
with water for a period of up to one month. Data show that since the 1961/1964 floods,
subsequent floods in the plains have been of relatively lower magnitudes. There is,
however, an indication that the frequency of occurrence of these low-magnitude
floods has increased.
The data do not indicate clearly whether there is a long-term increase in streamflow that could be related to increasing rainfall (see also Opere and Okello 2011a, b).
Although data for the period 2003–2012 show an increasing trend in streamflow, it
declined in the period 1964–1974. This suggests that in addition to inter-annual variation in river discharges, there may also be inter-decadal variations in streamflow that
could be explained by inter-decadal climatic variability. This requires further hydrological and climatological research.Regardless, it is significant that land-use/cover
change has substantial effects on streamflow in the basin. While forest cover has
been increasing slowly due to the implementation of reforestation programs in the
basin, more must be done, as suggested by previous studies that have shown that
increased forest cover in the basin results in decreased peak flood flows there (Opere
and Okello 2011a, b).
Flooding in the Kano plains has both direct and indirect impacts, which can have
positive and negative effects. Impact analysis based on various reports (see ICRAF
2002) shows that direct negative impacts of floods include water quality deterioration,
habitat degradation or alteration, river channel modification, siltation of water bodies
(dams, water pans, canals), destruction of fishing grounds, reduced fish catches,
destruction of infrastructure (water supplies, roads, bridges), loss of human life, loss
of livestock, creation of habitat for disease vectors, damage to farms, loss of crops,
reduced crop production, interruption of education/school programs, destruction of
property (e.g., houses, buildings and pit latrines), contamination of water supplies,
lack of clean water and disruption of social and economic activity.
Indirect negative impacts include loss of income, unemployment, economic stagnation, waterborne disease, and other health impacts (diarrhea, cholera, malaria,
typhoid, skin diseases, stress, and anxiety), increased incidence of livestock diseases,
a decline in education performance, lack of economic diversification, lack of diversification of income, reduced human productivity, conflicts, increased rural-urban
migration, increased dependency on donor assistance and grants, increased government expenditure (repairs, evacuation, health, relief), and degradation of recreation
opportunities.
Positive impacts of flooding include recharge of groundwater aquifers, supply
of fertile silt to the flood plains (including paddy fields), recharge of wetlands
and riparian zones, increased nutrient supply to Lake Victoria, and regeneration
of wetlands.
The overall adverse impact of flooding in the basin is increased poverty levels
among the majority of the people living in the basin. More than 65% of the population
there live below the poverty line (see also Swallow 2005).
J. U. Kitheka et al.
Three major flood events have occurred in the recent past: 1961/1964, 1997/1998,
and 2003/2004. During floods, the entirety of the Kano Plains is usually inundated
with water for a period of up to one month. Data show that since the 1961/1964 floods,
subsequent floods in the plains have been of relatively lower magnitudes. There is,
however, an indication that the frequency of occurrence of these low-magnitude
floods has increased.
The data do not indicate clearly whether there is a long-term increase in streamflow that could be related to increasing rainfall (see also Opere and Okello 2011a, b).
Although data for the period 2003–2012 show an increasing trend in streamflow, it
declined in the period 1964–1974. This suggests that in addition to inter-annual variation in river discharges, there may also be inter-decadal variations in streamflow that
could be explained by inter-decadal climatic variability. This requires further hydrological and climatological research.Regardless, it is significant that land-use/cover
change has substantial effects on streamflow in the basin. While forest cover has
been increasing slowly due to the implementation of reforestation programs in the
basin, more must be done, as suggested by previous studies that have shown that
increased forest cover in the basin results in decreased peak flood flows there (Opere
and Okello 2011a, b).
Flooding in the Kano plains has both direct and indirect impacts, which can have
positive and negative effects. Impact analysis based on various reports (see ICRAF
2002) shows that direct negative impacts of floods include water quality deterioration,
habitat degradation or alteration, river channel modification, siltation of water bodies
(dams, water pans, canals), destruction of fishing grounds, reduced fish catches,
destruction of infrastructure (water supplies, roads, bridges), loss of human life, loss
of livestock, creation of habitat for disease vectors, damage to farms, loss of crops,
reduced crop production, interruption of education/school programs, destruction of
property (e.g., houses, buildings and pit latrines), contamination of water supplies,
lack of clean water and disruption of social and economic activity.
Indirect negative impacts include loss of income, unemployment, economic stagnation, waterborne disease, and other health impacts (diarrhea, cholera, malaria,
typhoid, skin diseases, stress, and anxiety), increased incidence of livestock diseases,
a decline in education performance, lack of economic diversification, lack of diversification of income, reduced human productivity, conflicts, increased rural-urban
migration, increased dependency on donor assistance and grants, increased government expenditure (repairs, evacuation, health, relief), and degradation of recreation
opportunities.
Positive impacts of flooding include recharge of groundwater aquifers, supply
of fertile silt to the flood plains (including paddy fields), recharge of wetlands
and riparian zones, increased nutrient supply to Lake Victoria, and regeneration
of wetlands.
The overall adverse impact of flooding in the basin is increased poverty levels
among the majority of the people living in the basin. More than 65% of the population
there live below the poverty line (see also Swallow 2005).