Solid runoff assessment of Moscow territory

Abstract

Over half of the existing river valleys and gullies on the territory of Moscow (within the Moscow Ring Road) for the XVIII–XX centuries were buried because of land development. Along with this, a network of storm-water drains (underground pipes) was built with an average density of 6.9 km/km2. Now the impermeable surfaces (roofs of buildings, sidewalks, roads etc.) cover 50% of total Moscow territory. Surface runoff, including soil, suspended and dissolve loads now enters remaining streams and ponds through storm-water network. It has been estimated, that on average the annual solid runoff from the surface area of 880 km2 is about 160–250 m3/km2 (or 2.6–4 ton/ha per year). About 100 m3/km2 of sediment per year is being washed off from flat surfaces (e.g. fluvial terraces) with amplitudes of less than 6–7 m. The reason of increase sedimentation and dissolved substances in runoff is a poor maintained storm-water network, extensive urban development, and intensification of aeolian transit from construction sites. The total quantity of particulate matter (suspended or bedload) coming from the storm-water drains lead to an explosive increase in sediment runoff exceeding the transporting capacity of the preserved rivers. The potential of the Moskva River to remove the increased runoff of sediments and pollutants has now been completely exhausted.