| Summary: | Bawean is a small island with an area of ±200 km2 and located 150 km
north of Gresik City. Usually the people who live on islands, they demanded to
be independent in fulfilling their water needs. Fresh water supply in a small
island depends on the land ability to absorb rainfall. Land capability is influenced
by the hydrologic conditions of its land cover. Forested land can absorb the
rainfall better than other forms of land use. In Bawean Island, there are Bawean
Nature Reserve and Bawean Wildlife Sanctuary which have tropical rain forest
ecosystem, with an area of 4556,6 hectares or about 22% of the total area of the
island.
The aims of this research were to identify the potential and utilization of
Bawean Island�s water resource, water balance, and to set a land cover
improvement proposal for optimizing the water resource. The method used to
predict water resource potential was curve number developed by the US Soil
Conservation Service. This model is uses an index known as curve number. By
identifying the land curve number, the surface runoff will be discovered after the
rainfall. Water utilization was estimated by evaluating domestic use, which was
gathered from interviewing respondents in proportional random sampling, water
needs for agriculture (irrigation), livestock farming, education, offices, and
mosques. Water balance was obtained from water critical index equation. A land
cover improvement proposal was designed by restoring the land cover
hydrological conditions in order to decrease the surface runoff.
The results of this research showed that water resource potential was
520.983.873 m3 and water utilization for domestic use, agricultural, livestock,
education, offices, and mosque use were 48.766.863 m3/year. Water balance was
9,4% and classified as not critical yet. The proposed improvement land cover
resulted in a lessening curve number from 77,72 to 77,06 which had the effect of
decreasing surface run off and consequently increasing water resource potential to
526.646.486 m3.
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