Geographia Technica, Vol 15, Issue 2, 2020, pp. 57-71
PRELIMINARY ANALYSIS OF FLOODS INDUCED BY URBAN DEVELOPMENT IN YOGYAKARTA CITY, INDONESIA
Slamet SUPRAYOGI 
, Reviana LATIFAH , Muh Aris MARFAI
ABSTRACT: The growing population size in the City of Yogyakarta increases the need for settlement and supporting facilities, which consequently expands land-use conversion from previously vacant, productive, and conservative lands to built-up areas. Meanwhile, extensive development means wider impervious surface and gradually narrowing recharge areas, increasing the potential for flooding. This study aimed to analyze the land-use change in the last fourteen years and its relation to runoff coefficients, the maximum discharges occurring with the return periods of 2, 5, 10, and 25 years, and the inundated areas in each return period. The flood inundation was modelled using HEC-RAS. The results showed, in particular, the expansion of the settlement area during the period of 2004-2017. However, such change did not significantly alter the runoff coefficient and, by proxy, the maximum flood discharge. Spatially, the flood scenarios showed overflows from the upper and middle segments of the river.
Keywords: urban, flood, HEC-RAS, Indonesia
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