Ключевые слова: canal, circular, corrosion, danger, dirty, drainage, drop, ecological, ecology, environment, environmental, fall, falling, flood, floodwater, flow, flowing, fossil, ground, high, irrigation, liquid, movement, natural, nature, nobody, old, opening, outdoors, outfall, over, overflow, peace, pipe, pipeline, pollute, pollution, pour, quality, rain, rainwater, raw, run, runoff, stream, surface, tube, waste, water, wet,