Tana Delta Irrigation Project, Kenya: An Environmental Assessment

Rehabilitation of the Tana Delta Irrigation Project, Kenya: An Environmental Assessment.
Teams moved through the forest at a rate of approximately 1km/hr stopping to look for and
observe monkeys when sightings were made. At the end of each forest, discussions by the
team were undertaken to ascertain any double troop counts. 201 transects were carried out
with a total distance of 52.3 km. See Transects Map.
Two data sets were recorded. The first was the transect data set filled in by each field
technician at the start and end of transects. The forest name, transect number, GPS start
and end locations, bearing and time start and end were recorded.
The second data set was for the recording of primate sightings or vocalisations. The following
information was recorded: GPS reading of group location, species, number of individuals
counted, estimated number, behaviour of individual/troop, direction of movement and when
possible, sex and age,. In addition, quality of group count was indicated (good/incomplete),
and whether or not, it was a vocalisation. Counts were generally considered “good” if the
troop was seen moving as a whole, often between trees.
Age/sex was found to be difficult to judge accurately in colobus and mangabeys due to a
large flight distances. Age/sex was not recorded for sykes and baboons and group size for
both species was deemed inconsistent and was not recorded.
Equipment used included three Garmin Etrex Legend GPS’s and eight hand bearing
compasses of mixed brand but similar good quality.
GIS MAPPING
The use of Geographic Information System (GIS) was key to the analysis of the data
collected. ESRI ArcGIS Desktop 8.1 was used to process the data contained in a Microsoft
Access database.
Standards are considered important in the presentation of the maps and the following
standards apply in order that future field work may relate easily to these maps:
• Map Projection: The projection of the maps is Transverse Mercator, with the
Clarke 1880 Spheroid, and ARC 1960 Datum.
• Unit of measure is Metres
• Grid system is Universal Transverse Mercator, Zone 37 South
•
These standards are identical to those used on all topographic maps published by the Survey
of Kenya, and therefore all GPS co-ordinates and grid references can be used with those
publications.
The analysis of the data resulted in five maps being produced that display the results clearly.
Each map is explained in detail in the following sections.
Forests Surveyed Map
The areas that are shown as forest are actual areas that were censused by transects. These
“forests” were mosaics of open and closed canopy forest and bush and grassland and cannot
be considered actual forest size though it does give an indication of the reduction of forest
habitat from that indicated on the 19xx map.
The boundary of the forest displayed on this map is determined by tracing the transect start
and end points which indicate the beginning and end of the forest. For this reason the
boundaries and therefore the stated forest area sizes can only be considered estimates.
These maps also display the extent of the overall census area, and defines the current path of
the Tana River and the main infrastructure.
Please note that these maps are very high resolution, and printouts on a standard office
printer may not allow the clearest view. In that case refer to the supplied PDF versions of the
maps that will allow a high degree of zoom.
89