THE EFFECT OF FLOOD TO QUALITY INDEX OF SOIL PHYSICAL PROPERTIES AT THE DOWNSTREAM OF KURANJI RIVER WATERSHED, PADANG CITY

Abstract

The downstream of the Kuranji watershed of Padang City is vulnerable to flood due to the
changes of land use into settlements area. Land use changes have changed the soil physical properties and its
infiltration. The inundation has changed soil physical properties, such as layers, textures, volume weight,
pores, permeability, and soil organic matters. The objective of this research is to analyze the quality index of
soil physical properties due to flood at the watershed of the downstream area of Kuranji River of Padang City.
Research methodology adopted is by conducting a field survey. Location of the soil sample is selected by
purposive random sampling and was analyzed at the Department of Soil Science Andalas University. Soil
physical properties data was arranged as minimum data sets (MDS) to be analyzed with principal component
analysis to identify the main factors most affected by the flood. The results show that the main soil physical
properties influenced by the flood are texture and soil organic matter. Based on the calculation of selected
values from the MDS data, the quality of the downstream Kuranji watershed is moderate to good.