Abstract: A portable flood-barrier-system can include a portable block of substantial mass; and a deflatable bladder, a first portion of which is disposed on a substrate; the block being disposed at least partly on the first portion of the bladder so as to releasably compress the first portion between the block and the substrate and so releasably hold the first portion therebetween due to friction.

Abstract: Although water covers three-fourths of the earth's surface, it is unevenly distributed throughout. In some places, the demand for water exceeds the supply. There are several hundred desalination plants in the world, but it is very costly to produce fresh water. The Modular Clear Roof and Dark Basin Solar Still is a low-cost way to produce fresh water. The multiple modular roofs made of glass and/or clear plastic acts like a greenhouse. The sun shines through the roof creating heat. The salt water evaporates and condenses to make fresh water. This fresh water is collected in the half-pipes. Through a gravity flow, this water is collected in a water tank. This is feasible and effective in areas where the demand for water is high, especially in the equatorial or desert area.