Preliminary River Morphometry Analysis for Rafting Tourism in the Saba River, Bali Island, Indonesia Slamet Suprayogi 1 , Bachtiar W. Mutaqin 1,2 , Yuli Widyaningsih 3 , Galih Dwi Jayanto 3 , Muh Rizali Umarella 4 , Muh Aris Marfai 1* 1 Department of Environmental Geography, Faculty of Geography, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia 2 Laboratoire de Géographie Physique, UMR 8591, Université Paris 1 Panthéon Sorbonne, Paris 92190, France 3 Master Program on Coastal Area and Watershed Planning and Management, Faculty of Geography, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia 4 Doctoral Program of Geography, Faculty of Geography, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia Corresponding Author Email: arismarfai@ugm.ac.id https://doi.org/10.18280/ijsdp.150505 ABSTRACT Received: 14 April 2020 Accepted: 8 June 2020 This study was designed to calculate the morphometry along the SWISS rafting route, as well as map the whitewater and analyze the risk management of the rafting tourism at the Saba River in Buleleng Regency, Bali, Indonesia. The whitewater mapping was conducted using a river morphometry analysis, and the morphometry data was collected using field measurements, topographics, and a geographic information systems vector analysis. The river morphometry, which plays an important role in the rafting sport, was quantified using the spatial aspects, topography, length of the main river, and river flow. The results showed that the river had a slope of 14.2 m/km, a dam-regulated flow rate of up to 4.02 m 3 /s, and water levels of 0.4–0.7 m. These figures indicate that the river channel and its hydrological characteristics are suitable for rafting activities, and it has been categorized as grade 2–3 rapids. Due to the improper risk management of whitewater rafting, this research recommends improving the skills of the tour guides or the members of the local tourism awareness group and preparing emergency response strategies that consider the site’s accessibility and the available medical services. Keywords: whitewater rafting, morphometry, mapping, management, risk, tourism, Bali, Indonesia 1. INTRODUCTION Ecosystems provide several benefits for humans, such as scenic beauty and recreational activities [1-4]. As an ecosystem that shares the same benefits [5], many rivers have been developed into tourist attractions, including rafting. Whitewater rafting is a natural attraction that stimulates adrenaline. According to the Indonesian Rafting Federation (FAJI), rafting is an activity that involves navigating rivers using either rubber boats or something similar, which is steered by a crew of two or more people who rely on the power of rowing. The rafting was first introduced in Indonesia in 1970 and has been recognized as a sports activity since 1975. In 1994, the first National Rafting Championship was held in Ubud, Bali. Sobek Expedition first commercialized the rafting, and it continues to grow in popularity in Indonesia [6]. Rafting is nature-based tourism; therefore, it depends on the natural or morphometric conditions, especially of the river. The flow discharge, width, slope, and turbulence of the river are the main morphometric factors [7] that affect the formation of whitewater, both directly and indirectly [6, 8]. For example, the ideal river slope for whitewater rafting is 10–20 m/km [6]. A more complex morphometry analysis for the river tourism attraction has been conducted using the following parameters: stream order, stream length, mean stream length (Lsm), stream length ratio (RL), bifurcation ratio (Rb), drainage density (Dd), drainage frequency (Fs), texture ratio (T), form factor (Rf), circularity ratio (RC), maximum basin length (Lg), constant of channel maintenance (C), relief ratio (Rh), and ruggedness number (RN) [9]. Furthermore, the riverbed roughness determines the emergence of turbulence, while the cross-sectional width controls the lateral distribution of the river flow discharge. An analysis is used for a broader perspective to determine the route of water tourism by assessing the availability of the water quantity, as well as the measurements related to the possibility of navigational techniques [10]. In addition, the watercourse incline is a factor in determining the speed and considering the difficulty by looking at the river sinuosity. Although this research uses parameters that are not as complex as the previous studies [9, 10], this research is considered a pioneer, as it provides new insight and understanding of the use of morphometric data, topography, and its integration with spatial analysis in a geographic information systems (GIS) vector environment. Since safety is an unavoidable factor that must be considered during the development of rafting tourism, the river flood hazard analysis is essential. Flooding is a threat to whitewater rafting; in response to this, morphometry data can help to predict the river flood discharge [11-13]. The flood pattern is illustrated by a graph that shows the relation between the flow discharge and time and is called the flood hydrograph. It represents the product of the interaction between the climate and the physiographical condition of the river [14]. International Journal of Sustainable Development and Planning Vol. 15, No. 5, August, 2020, pp. 631-638 Journal homepage: http://iieta.org/journals/ijsdp 631