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used for editing and data management. Geodatabases work across a range of database 
management system (DBMS) architectures and file systems, come in many sizes, and 
have varying numbers of users. They can scale from small, single-user databases built 
on files up to larger workgroup, department, and enterprise geodatabases accessed by 
many users. 
The Nee Soon file geodatabase is a single centralised location with metadata 
that gives information on the ownership and authorisation of data. Currently, the file 
geodatabase contains 68 layers of both raster and feature layers. ArcMap related layers 
are categorised as groups shown in Table 2. All the digital information is retained 
by the National Biodiversity Centre, National Parks Board, Singapore, and (with 
appropriate access restrictions and provisos) on the web-based information platform 
named BIOME. 
Field hydrology and geomorphology 
Effective conservation of the Nee Soon Catchment will require strategies informed by 
the dynamic baseline of the system, as well as the sources of current anthropogenic 
disturbance. While conservation efforts may be primarily concerned with preserving 
the unique ecosystems and highly diverse floral and faunal communities, these systems 
are intrinsically linked to the geomorphic and hydrological stability of the catchment. 
Thus, the underlying hydrology and sedimentary processes must be considered 
when implementing management efforts. This consideration was fundamental to the 
rationale, aims, design, conduct and deliverables of the project, linking all the work by 
the various teams. 
Soil erosion reduces the water holding capacity and results in more rapid water 
runoff, causing soil organic matter and nutrients to be transported downslope. This 
process can greatly affect species diversity of plants, animals, and microbes by rapidly 
exporting water, nutrients, and other biological resources out of the biological system 
(Zuzao & Pleguezuelo, 2008). Erosional processes are aggravated by a reduction in 
forestland cover (Rahman et al., 1991); the canopy of vegetation stabilises the hillslopes 
through the adsorption of rainfall and binding root systems drawing moisture from the 
groundwater. This protects the ground surface by shielding it from rain impact as well 
as removing water from the soils and reducing the frequency of soil saturation and 
subsequent surface runoff. Landscape modifications to facilitate farming, irrigation, 
and drainage has altered stream flow and subsequently contributed to sedimentation in 
low lying areas (Schumm, 1973). 
Stream channel bunding in the lower catchment has significantly deepened the 
valley floor, preventing water from spreading towards the expressway. This enhances 
erosion along the stream channel and limits the development of the swamp forest 
area as well as likely increasing the sediment load to the Lower Seletar Reservoir. 
One potential strategy for mitigating these enhanced erosional processes is to fill 
in the channel to restore the hydrological functioning of the swamp. However, this 
intervention may affect fish communities that have since developed in the channel. 
