The Ground Penetrating Radar (GPR) method commonly known as Georadar, a nondestructive geophysical method that uses electromagnetic waves. This method is widely used to determine conditions under the surface such as mapping structures and subsurface lithology or buried objects. In this study, the GPR measurement using Geoscanners AKULA A9000 + Antenna GCB3070 is conducted to detect the presence or capacity of a septic tank. The GPR data were initially processed using matGPR based on MATLAB. GPR data on each measuring line is processed first, a series of filters and gaining have been conducted such as Adjust Signal Position, Remove DC, Dewow, Inverse Amplitude Decay, Remove Global Background, Karhunen-Loeve Filter, then time to depth conversion with adjusted parameters. From the result of parameter analysis in processing data, found that the GPR data can be interpreted which show the underground septic tank in the study area with the presence of diffraction signatures.

Changes in land use in an urban area, such as Surabaya have a major influence on the balance of nature and the environment of its people. Analysis related to changes in land use from time to time is important to maintain the dynamics of development in Surabaya. The land use identification method in this study utilizes the Normalized Difference Vegetation Index (NDVI) to identify the effect of differences in the spectrum due to vegetation and non-vegetation. Satellite image data is analysed based on the spectrum and the results of the land cover classification have been obtained. From six classes of land cover classification results, it was found that the largest decreasing trend in the area was in class 6, one of which contained urban forest around 13% to 9%. For the trend of increasing area, the largest area occurs in class 5, which includes a land cover of undeveloped land which has the potential for building and infrastructure construction to be carried out around 15% to 19%. Surabaya has a development pattern on the use of vacant land for public and private facilities, which has the potential to reduce the area of an urban forest. Given that the function of forests in urban areas is quite necessary for the stability of air temperature and maintaining the beauty of the city.