Ключевые слова: abstract, architecture, background, bright, channel, circle, concept, concrete, creepy, dark, deep, design, dirty, drain, drainage, drainage system, element, empty, exit, flow, geology, graphic, industrial, inside, light, mine, passage, perspective, pipe, pipeline, plant, pollution, sewage, sewer, sewerage, shine, space, stone, subterranean, texture, tube, tubing, tunnel, underground, urban, view, wall, wastewater, water,