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BYWASIKE L ARNOLD
F19/1669/2009
APPLICATION OF GEOSPATIAL TECHNOLOGIES IN THE SELECTION OF A SUITABLE DAM SITE
ON THE LOWER EWASO NYIRO RIVER
INTRODUCTION
• Narok and Kajiado north counties describe areas that have been grossly under developed due to the predominant arid and semi-arid conditions. The Ewaso Nyiro basin, being in this area presents a possible solution to this problem by providing a very essential resource, water.
• Damming has been identified as a way of ensuring constant supply of water over the different seasons
• The focus of this project is to identify an area on the river within the river valley, using GIS and mapping tools that will be most suitable for the location of the dam
PROBLEM STATEMENT
• A dam is needed in the area in order to ensure constant water supply which forms part of the initiatives for economic development in the area.
• The main problem is to establish a suitable location that a dam could be constructed depending on a number of factors that have been conventionally identified
• This will be solved by considering the affecting factors as criteria and carrying out multi-criteria suitability analysis using GIS tools on order to arrive at a result showing the proposed dam site location
OBJECTIVESMain ObjectiveIdentify a suitable dam site on the lower Ewaso Nyiro River with the aid of Geospatial technologies.
Specific objectives To identify criteria for selecting a suitable dam site and establish respective weights To produce a suitability map for each criterion To carry out multi criteria analysis resulting in the production of the final dam site suitability map To review the results and draw appropriate conclusions and recommendations
METHODOLOGYSTAGE ONE
INTRODUCTORY BACKGROUND
REVIEW OF RELATED LITERATURE
CONCEPTUAL ANALYSIS
STAGE TWO
DATA TYPES AND SOURCES
DATA TYPES-Cadastral Maps-Aerial imagery-Geology Maps
DATA ANALYSIS-Data Compilation-Spatial analysis
DATA PRESENTATION
-Maps
STAGE THREE
RESULTS FINDINGS AND PRESENTATION
ANALYTICAL PRESENTATIONModel
CONCLUSION-Conclusion-Recommendations
CRITERIA ADOPTED
CRITERION PARAMETERS
Human
activity
1 km from zones and 500 m from points.
Fault lines 500 m from fault lines
River Within a 250 meter corridor of the river
Geology Areas with a stability value of ≥ 5
Elevation Areas with a slope of ≥ 50%
WEIGHTINGCriterion Weight
Proximity to the river 33%
Stable rock foundation 27%
Topography 20%
Fault lines 13%
Human activity 7%
Weighting by rank order formula
AREA OF STUDY Area west of Lake Magadi
Covers potions of Narok and Kajiado north counties
Area within the Ewaso Nyiro basin
To the north of Shompole conservancy
INPUT DATA SETS
Geology Map Levels or rock
stability
DEM
Human activities, population
points suitability map
Human activities,
population zones
suitability map
Fault lines suitability
map
River suitability
map
Slope suitability
map
Geology suitability
map
Overlaid suitability map
for dam location
EXTRACTED SUITABLE AREAS
FINAL DAM LOCATION
SUITABILITY MAP
DISCUSSION OF RESULTS A clear zone in which the dam can be constructed was
identified. This zone fulfils all the parameters preset in the multi-criteria analysis
Levels of accuracy in the raster overlay are dependent on the resolution of the largest data set. For more accurate results, commercial data at a higher resolution can be acquired
The results give a zone rather than a point where the dam could be located
CONCLUSIONTwo zones exist along the river which present the most suitable locations for the dam. All the objectives to the study were achieved
RECOMMENDATIONAn actual simulation of the dam should be done to determine reservoir size and siting within the zones and the hydraulic head; factors which will narrow down the location of the dam within the identified zones
