Developing a high resolution groundwater model for Indonesia

Groundwater is important in many parts of Indonesia. It serves as a primary source of drinking water and industrial activities. During times of drought, it sustains water flows in streams, rivers, lakes and wetlands, and thus support ecosystem habitat and biodiversity, as well as preventing hazardous forest fire. Besides its importance, groundwater is known as a vulnerable resource as unsustainable groundwater exploitation and management occurs in many areas of the country. Therefore, in order to ensure sustainable management of groundwater resources, monitoring and predicting groundwater changes in Indonesia are imperative. However, large-extent groundwater models to assess these changes on a regional scale are almost non-existent and are hampered by the strong topographical and lithological transitions that characterize Indonesia. In this study, we built an 1 km resolution of steady-state groundwater model for the entire Indonesian archipelago (total inland area: about 2 million km2). Here we adopted the approach of Sutanudjaja et al. (2011) in order to make a MODFLOW (McDonald and Harbaugh, 1988) groundwater model by using only global datasets. Aquifer schematization and properties of the groundwater model were developed from available global lithological map (e.g. Dürr et al., 2005; Gleeson et al., 2010; Hartmann and Moorsdorf, 2012). We forced the groundwater model with the output from the global hydrological model PCR-GLOBWB (van Beek et al., 2011), specifically the long term net groundwater recharge and average surface water levels derived from routed channel discharge. Results are promising. The MODFLOW model can converge with realistic aquifer properties (i.e. transmissivities) and produce reasonable groundwater head spatial distribution that reflects the positions of major groundwater bodies and surface water bodies in the country. For this session, we aim to demonstrate and discuss the results and the prospects of this modeling study. References: Dürr, H. H., Meybeck, M., & Dürr, S. H.: Lithologic composition of the Earth's continental surfaces derived from a new digital map emphasizing riverine material transfer, Global Biogeochem. Cycles, 19, GB4S10, http://dx.doi.org/10.1029/2005GB002515, 2005. Gleeson, T., Smith, L., Moosdorf, N., Hartmann, J., Dürr, H. H., Manning, A. H., van Beek, L. P. H., & Jellinek, A. M.: Mapping permeability over the surface of the earth. Geophys. Res. Lett. 38 (2), L02401, http://dx.doi.org/10.1029/2010GL045565, 2011. Hartmann, J., & Moosdorf, N.: The new global lithological map database GLiM: A representation of rock properties at the Earth surface, Geochem. Geophys. Geosyst., 13, Q12004, http://dx.doi.org/10.1029/2012GC004370, 2012. McDonald, M. & Harbaugh, A.: A modular three-dimensional finite-difference ground-water flow model, US Geological Survey, http://pubs.water.usgs.gov/twri6a1, 1988. Sutanudjaja, E. H., van Beek, L. P. H., de Jong, S. M., van Geer, F. C., & Bierkens, M. F. P.: Large-scale groundwater modeling using global datasets: a test case for the Rhine-Meuse basin, Hydrol. Earth Syst. Sci., 15, 2913-2935, http://dx.doi.org/10.5194/hess-15-2913-2011, 2011. van Beek, L. P. H., Wada, Y., & Bierkens, M. F. P.: Global monthly water stress: 1. Water balance and water availability. Water Resources Research 47 (7), W07517, http://dx.doi.org/10.1029/2010WR009791, 2011