Chap 4

Question 1

what is drainage

Answer 1

The flow of water through well-defined channel

Question 2

what is a drainage system made up of

Answer 2

it refers to the direction and destination of the rivers
- a principal river and its tributaries (the rivers that flow into it)

Question 3

what is drainage pattern

Answer 3

it refers to the surface arrangement of the main rivers and their tributaries.

Question 4

where does a river system begin and end?

Answer 4

A river system begins at a place called the source or headwater and ends at a point called mouth

Question 5

what is the drainage pattern of an area due?

Answer 5

its the outcome of the geological processes,
-nature and structure of rocks,
- topography,
-slope,
-amount and the periodicity of the flow

Question 6

what is a drainage basin?

Answer 6

Its an area of land where water from rain or snow melt drains downhill into a body of water such as a river, lake, wetland or ocean. is bounded by and separated from other river basins by a water divide or topographic divide.

Question 7

what are the 3 broadly classified drainage systems of ethiopia ?

Answer 7

western , southeastern, and rift valley drainage systems
the western and southeastern systems are divided by the rift valley system.

Question 8

info about the Western drainage system

Answer 8

-1. its the largest of the country -> 40% total area and carries 60% of annual water flow
2. it has 4 major river basins : tekeze, abay, baro akobo, ghibe

Question 9

info about the southeastern drainage system

Answer 9

1. the entire southeastern region is drained by the southeastern system
2. the basin slopes south eastwards
3. major highlands are arsi, bale, sidama, harerghe
4. wabshebelle and ghenale are the main rivers that drain the basin

Question 10

info about the rift valley drainage system

Answer 10

1. it has small amount of rainfall, high evaporation and small catchment area.
2. Awash is the major river basin
3. there is no general flow direction, it goes in all direction
4. its sub basin has a nbr of lakes ( interconnected) and small streams

Question 11

what are the general characteristics of ethiopian rivers?

Answer 11

1. they originate from the highlands
   2.rapids and waterfalls along their course
   3.cuts, steep sided river valleys and deep gorges along their course.
2. they flow on steep slopes
3. arise from high places and flow to the country’s borders
4. seasonal fluctuation
5. they serve as boundaries
6. they are given new names after they cross the country’s borders

Question 12

what is a transboundary river?

Answer 12

its a river that crosses at least one political border

Question 13

the ethiopian lakes

Answer 13

• almost all of them resulted from tectonic process during quaternary period of cenozoic era
• located within the rift valley system
  -lake tana or abaya is the biggest lake
• ziway and shala deepest

Question 14

what are the crater lakes?

Answer 14

1. bishoftu
2. wonchi
3. hayk
4. mount zikwala
5. lake ashenge

Question 15

what are the man made lakes?

Answer 15

1. koka
2. fincha
3. melka wakena

Question 16

what is Ground water resource of eth determined by and its potential?

Answer 16

• they are determined by climatic and geophysical conditions
• its potential : 12-30

Question 17

what is the potential development uses of water resource of eth?

Answer 17

1. hydro electric potential
2. irrigation and transportation
3. fishing and recreation

Question 18

what are the characteristics of ethiopian rivers

Answer 18

• Almost all major rivers originate from the highlands elevating more than 1500 meters
  above sea level,
• Majority of Ethiopian rivers are trans-boundary,
• Due to the marked seasonality of rainfall, Ethiopian rivers are characterized by extreme
  seasonal fluctuation. In the wet season, runoff is higher and rivers are full bursting their
  banks, destroying small bridges, damage roads and flooding low lands; during the dry
  seasons they became mere trickles of water or even dry up,
   Due to surface ruggedness they have rapids and waterfalls along their course,
   They have cuts, steep-sided river valleys and deep gorges along their courses,
   Rivers in Ethiopia flow on steep slopes having steep profiles.
   Some of the rivers serve as boundaries, both international and domestic administrative
  units

Question 19

what are the water resources potentials in ethiopia?

Answer 19

1. Ethiopian rivers have a very high potential for generating electricity (gerd)
   The major problem related to the use of Ethiopian rivers for the generation of hydroelectric power is the seasonal flow fluctuations and impact of climate change and variabilities
2. The terrain in Ethiopia is so rugged that it limits the uses of Ethiopian rivers both for irrigation
   and transportation. In the highlands, steep slopes, rapids, waterfalls, narrow and deep valleys and
   gorges are important obstacles. But on the lowlands, their demand for irrigation is high. Majority of Ethiopian rivers are not suitable for transportation
3. The majority of Ethiopian lakes are rich in fish
   However, some of the lakes are currently threatened by sedimentation, invasive species (water hyacinth), over exploitation and expansion of investments
   around lakes.