Stream flow, ground water and climate change 
189 
the model setup. The spatial and temporal variations of LAI and reference ET retrieved 
from remote sensing data, i.e. the reference ET from MODIS and LAI from GLASS- 
MODIS, with the aid of the surveyed RD, are used to establish a two-layer water 
balance model to account for the water loss from evapotranspiration and the amount 
of water recharging to the saturated zone. In addition, the field measurements from 
piezometers and stream sondes have been processed and integrated to calibrate and 
validate the model parameters. 
Twelve scenarios were introduced, being the combinations of various reservoir 
operating levels and the projected future rainfall resulting from climate change study. 
Despite rainfall appearing to be the most influential factor for the overall catchment 
water availability, i.e., the spatial average over the catchment, it is interesting to 
observe the different contributing factors of both rainfall and reservoir water at sub¬ 
catchment levels. The effects of the two inputs differ depending on the locations as 
can be seen from the hydrological maps. This spatial distribution information is of 
importance should eco-hydrological management be approached at sub-catchment 
levels or spatially distributed. 
Several possible management strategies are put forth to mitigate severe 
drought and flood resulting from the projected climate change impacts as simulated 
in Scenarios 9 and 12. These have yet to be evaluated in terms of cost, engineering 
feasibility, and biological impacts. Introducing water sources (point sources) in the 
catchment upstream is a potential strategy to mitigate future drought. Retention ponds 
could be a simple and effective solution in mitigating flooding and simultaneously 
promoting habitat for aquatic fauna. Discussion of these two possibilities does not 
represent a commitment to carry them out, as they must be considered in relation to 
recommendations from other teams in the study of Nee Soon freshwater swamp forest. 
ACKNOWLEDGEMENTS. This study forms part of the research project “Nee Soon Swamp 
Forest Biodiversity and Hydrology Baseline Studies—Phase 2” funded by National Parks Board 
(NParks), Singapore. The authors are also grateful for access to data generously provided by 
the Public Utilities Board (PUB), Singapore, that helped to make this study possible. 
References 
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