Hydrology and Earth System Sciences Discussions, 2014
Endorheic basins, often found in semi-arid and arid climates, are particularly sensitive to varia... more Endorheic basins, often found in semi-arid and arid climates, are particularly sensitive to variation in fluxes such as precipitation, evaporation and runoff, resulting in variability of river flows as well as of water levels in endpoint lakes that are often present. In this paper we apply the indicators of hydrological alteration (IHA) to characterise change to the natural flow regime of the Omo-Ghibe Basin in southern Ethiopia. Little water resource infrastructure has been developed in the basin to date, and it is considered pristine. The basin is endorheic and is the main source of flow to Lake Turkana in the East African Rift Valley. The water level in Lake Turkana shows significant fluctuation, but increase of its level can be observed over the past 20 years. The reasons are currently not well understood. Of the five groups of hydrological characteristics in the IHA (magnitude, timing, duration, frequency and variability), only those related to magnitude were found to show significant trends, with the main trend being the increase of flow during the dry season. This trend was not reflected in climatological drivers such as rainfall, evaporation and temperature (which shows a positive trend), but rather is attributed to the substantial changes in land use and land cover in the basin. The change in the basin hydrology is apparent mainly in the more humid part of the basin. The significant shift from forest and woodland to grassland and cropland results in a decrease of actual evaporation and subsequent increase in (dry season) runoff. The long-term trend of the increasing levels in Lake Turkana are related to these trends in dry season flows, while shorter-term fluctuations of the lake levels are attributed primarily to anomalies in consecutive wet and dry season rainfall.
Abstract.
Endorheic basins, often found in semi-arid and
arid climates, are particularly sensit... more Abstract.
Endorheic basins, often found in semi-arid and
arid climates, are particularly sensitive to variation in fluxes
such as precipitation, evaporation and runoff, resulting in
variability of river flows as well as of water levels in end-
point lakes that are often present. In this paper we apply
the indicators of hydrological alteration (IHA) to characterise
change to the natural flow regime of the Omo–Ghibe Basin
in southern Ethiopia. Little water resource infrastructure has
been developed in the basin to date, and it is considered pris-
tine. The basin is endorheic and is the main source of flow to
Lake Turkana in the East African Rift Valley. The water level
in Lake Turkana shows significant fluctuation, but increase of
its level can be observed over the past 20 years. The reasons
are currently not well understood.
Of the five groups of hydrological characteristics in the
IHA (magnitude, timing, duration, frequency and variabil-
ity), only those related to magnitude were found to show sig-
nificant trends, with the main trend being the increase of flow
during the dry season. This trend was not reflected in clima-
tological drivers such as rainfall, evaporation and tempera-
ture (which shows a positive trend), but rather is attributed
to the substantial changes in land use and land cover in the
basin. The change in the basin hydrology is apparent mainly
in the more humid part of the basin. The significant shift
from forest and woodland to grassland and cropland results
in a decrease of actual evaporation and subsequent increase
in (dry season) runoff. The long-term trend of the increasing
levels in Lake Turkana are related to these trends in dry sea-
son flows, while shorter-term fluctuations of the lake levels
are attributed primarily to anomalies in consecutive wet and
dry season rainfall.
Hydrology and Earth System Sciences Discussions, 2014
Endorheic basins, often found in semi-arid and arid climates, are particularly sensitive to varia... more Endorheic basins, often found in semi-arid and arid climates, are particularly sensitive to variation in fluxes such as precipitation, evaporation and runoff, resulting in variability of river flows as well as of water levels in endpoint lakes that are often present. In this paper we apply the indicators of hydrological alteration (IHA) to characterise change to the natural flow regime of the Omo-Ghibe Basin in southern Ethiopia. Little water resource infrastructure has been developed in the basin to date, and it is considered pristine. The basin is endorheic and is the main source of flow to Lake Turkana in the East African Rift Valley. The water level in Lake Turkana shows significant fluctuation, but increase of its level can be observed over the past 20 years. The reasons are currently not well understood. Of the five groups of hydrological characteristics in the IHA (magnitude, timing, duration, frequency and variability), only those related to magnitude were found to show significant trends, with the main trend being the increase of flow during the dry season. This trend was not reflected in climatological drivers such as rainfall, evaporation and temperature (which shows a positive trend), but rather is attributed to the substantial changes in land use and land cover in the basin. The change in the basin hydrology is apparent mainly in the more humid part of the basin. The significant shift from forest and woodland to grassland and cropland results in a decrease of actual evaporation and subsequent increase in (dry season) runoff. The long-term trend of the increasing levels in Lake Turkana are related to these trends in dry season flows, while shorter-term fluctuations of the lake levels are attributed primarily to anomalies in consecutive wet and dry season rainfall.
Abstract.
Endorheic basins, often found in semi-arid and
arid climates, are particularly sensit... more Abstract.
Endorheic basins, often found in semi-arid and
arid climates, are particularly sensitive to variation in fluxes
such as precipitation, evaporation and runoff, resulting in
variability of river flows as well as of water levels in end-
point lakes that are often present. In this paper we apply
the indicators of hydrological alteration (IHA) to characterise
change to the natural flow regime of the Omo–Ghibe Basin
in southern Ethiopia. Little water resource infrastructure has
been developed in the basin to date, and it is considered pris-
tine. The basin is endorheic and is the main source of flow to
Lake Turkana in the East African Rift Valley. The water level
in Lake Turkana shows significant fluctuation, but increase of
its level can be observed over the past 20 years. The reasons
are currently not well understood.
Of the five groups of hydrological characteristics in the
IHA (magnitude, timing, duration, frequency and variabil-
ity), only those related to magnitude were found to show sig-
nificant trends, with the main trend being the increase of flow
during the dry season. This trend was not reflected in clima-
tological drivers such as rainfall, evaporation and tempera-
ture (which shows a positive trend), but rather is attributed
to the substantial changes in land use and land cover in the
basin. The change in the basin hydrology is apparent mainly
in the more humid part of the basin. The significant shift
from forest and woodland to grassland and cropland results
in a decrease of actual evaporation and subsequent increase
in (dry season) runoff. The long-term trend of the increasing
levels in Lake Turkana are related to these trends in dry sea-
son flows, while shorter-term fluctuations of the lake levels
are attributed primarily to anomalies in consecutive wet and
dry season rainfall.
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Papers by FIKADU WORKU
Endorheic basins, often found in semi-arid and
arid climates, are particularly sensitive to variation in fluxes
such as precipitation, evaporation and runoff, resulting in
variability of river flows as well as of water levels in end-
point lakes that are often present. In this paper we apply
the indicators of hydrological alteration (IHA) to characterise
change to the natural flow regime of the Omo–Ghibe Basin
in southern Ethiopia. Little water resource infrastructure has
been developed in the basin to date, and it is considered pris-
tine. The basin is endorheic and is the main source of flow to
Lake Turkana in the East African Rift Valley. The water level
in Lake Turkana shows significant fluctuation, but increase of
its level can be observed over the past 20 years. The reasons
are currently not well understood.
Of the five groups of hydrological characteristics in the
IHA (magnitude, timing, duration, frequency and variabil-
ity), only those related to magnitude were found to show sig-
nificant trends, with the main trend being the increase of flow
during the dry season. This trend was not reflected in clima-
tological drivers such as rainfall, evaporation and tempera-
ture (which shows a positive trend), but rather is attributed
to the substantial changes in land use and land cover in the
basin. The change in the basin hydrology is apparent mainly
in the more humid part of the basin. The significant shift
from forest and woodland to grassland and cropland results
in a decrease of actual evaporation and subsequent increase
in (dry season) runoff. The long-term trend of the increasing
levels in Lake Turkana are related to these trends in dry sea-
son flows, while shorter-term fluctuations of the lake levels
are attributed primarily to anomalies in consecutive wet and
dry season rainfall.
Endorheic basins, often found in semi-arid and
arid climates, are particularly sensitive to variation in fluxes
such as precipitation, evaporation and runoff, resulting in
variability of river flows as well as of water levels in end-
point lakes that are often present. In this paper we apply
the indicators of hydrological alteration (IHA) to characterise
change to the natural flow regime of the Omo–Ghibe Basin
in southern Ethiopia. Little water resource infrastructure has
been developed in the basin to date, and it is considered pris-
tine. The basin is endorheic and is the main source of flow to
Lake Turkana in the East African Rift Valley. The water level
in Lake Turkana shows significant fluctuation, but increase of
its level can be observed over the past 20 years. The reasons
are currently not well understood.
Of the five groups of hydrological characteristics in the
IHA (magnitude, timing, duration, frequency and variabil-
ity), only those related to magnitude were found to show sig-
nificant trends, with the main trend being the increase of flow
during the dry season. This trend was not reflected in clima-
tological drivers such as rainfall, evaporation and tempera-
ture (which shows a positive trend), but rather is attributed
to the substantial changes in land use and land cover in the
basin. The change in the basin hydrology is apparent mainly
in the more humid part of the basin. The significant shift
from forest and woodland to grassland and cropland results
in a decrease of actual evaporation and subsequent increase
in (dry season) runoff. The long-term trend of the increasing
levels in Lake Turkana are related to these trends in dry sea-
son flows, while shorter-term fluctuations of the lake levels
are attributed primarily to anomalies in consecutive wet and
dry season rainfall.