Runoff

Runoff, run-off or RUNOFF may refer to:

Runoff / run-off / RUNOFF

"Runoff / run-off ..."

Surface runoff

Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the earth's surface. This might occur because soil is saturated to full capacity, because rain arrives more quickly than soil can absorb it, or because impervious areas (roofs and pavement) send their runoff to surrounding soil that cannot absorb all of it. Surface runoff is a major component of the water cycle. It is the primary agent in soil erosion by water.

Runoff that occurs on the ground surface before reaching a channel is also called a nonpoint source. If a nonpoint source contains man-made contaminants, or natural forms of pollution (such as rotting leaves) the runoff is called nonpoint source pollution. A land area which produces runoff that drains to a common point is called a drainage basin. When runoff flows along the ground, it can pick up soil contaminants including, but not limited to petroleum, pesticides, or fertilizers that become discharge or nonpoint source pollution.

Two-round system

The two-round system (also known as the second ballot, runoff voting or ballotage) is a voting system used to elect a single winner where the voter casts a single vote for their chosen candidate. However, if no candidate receives the required number of votes (usually an absolute majority or 40-45% with a winning margin of 5–15%), then those candidates having less than a certain proportion of the votes, or all but the two candidates receiving the most votes, are eliminated, and a second round of voting is held.

The two round system is used around the world for the election of legislative bodies and directly elected presidents. For example, it is used in French presidential, legislative, and departmental elections. In Italy, it is used to elect mayors, but also to decide which party or coalition receives a majority bonus in city councils and in the lower house of the Parliament. A two-round system is used also to elect the presidents of Afghanistan, Argentina, Austria, Brazil, Bulgaria, Burkina Faso, Cape Verde, Chile, Colombia, Costa Rica, Croatia, Czech Republic, Cyprus, Dominican Republic, Ecuador, Egypt, El Salvador, Finland, Ghana, Guatemala, Haiti, India, Indonesia, Liberia, Peru, Poland, Portugal, Romania, Senegal, Serbia, Slovakia, Slovenia, Timor-Leste, Turkey, Ukraine, Uruguay, Zimbabwe – see: Table of voting systems by nation. Historically it was used in the German Empire of 1871–1918, and in New Zealand in the 1908 and 1911 elections.