Effects of Land Cover, Evapotranspiration, and Rainfall on Total Runoff in the Gumbasa River Basin, Central Sulawesi, Indonesia

Abstract

Land use patterns in various forms and ways will have an impact on the environment. Indications of a decrease in the carrying capacity of the environment in a region can be seen from various disasters that occur such as floods, landslides, and droughts. Therefore, changes in land use from nonbuilt land to build land will stimulate the amount of runoff water. This study aims to determine the effect of changes in land use, evapotranspiration, and rain on total runoff. This research was carried out in the Gumbasa Watershed. Data is needed in the form of primary data (soil characteristics) and secondary data (rain, climatology, a map of the earth and a map of land use). The rainfall data used are Bora, Palolo, Wuasa, Kulawi and Bangga Bawah stations with observations for 14 years (2002-2015). Climatology data was used by Bora Station with observations for 14 years (2002-2015). The analysis was carried out namely: regional rainfall, evapotranspiration, MockWyn-UB model and linear regression. The linear line equation obtained: Y = 97.325-0.747X 1 + 0.697 X 2 + 0.442 X 4 + 0.447 X 5. This equation has been tested statistically and fulfilled the linear regression requirements. Based on the above equation, it can be said that: 1). Forest land is an excluded variable so that it is not in the equation. 2). The smaller the evapotranspiration and the greater the rainfall and the area of mixed gardens and open land, the greater the runoff, and vice versa. Keywords-Gumbasa Watershed, MockWyn-UB Model, Linear Regression I. INTRODUCTION The phenomenon of climate change is a very serious challenge facing the world. Climate change is increasingly evident and affects various aspects of life, whether individual or domestic, even to the global development sector. On the other hand, it is increasingly recognized that accelerating the occurrence of climate change begins with human decisions and behavior which then accumulate massively and change the weather elements, especially the temperature that causes the phenomenon of global warming. Edi Nurrohcman (2018) [1] stated that the hydrological cycle is the rotation of water that never stops from the atmosphere to the earth and returns to the atmosphere through condensation, precipitation, evaporation, and transpiration. The hydrological system is a series of soil type elements, land use, topography and interrelated slope lengths between one component and the other components so as to form a mutually influencing unit towards the balance of the water system. Changes in the hydrological cycle are changes in behavior and function of surface water, namely decreasing the base flow and increasing surface flow which causes an imbalance in water management and the occurrence of flooding and inundation in the downstream area Indonesia is one of the developing countries that is carrying out development in various sectors. As is known so far, development provides many benefits, especially the provision of employment for the community, but in addition, the development also requires environmental sacr...

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