Run-Off Characteristics of Streams Report by: Rey Micheal Estela Homer Hermogenes

Streams

Streams A stream is a body of water with a current confined within a bed or stream banks. Streams serves as a conduit in the water cycle, instruments in groundwater recharge and corridors for fish and wildlife migration

Streams are responsible for three of the most important functions in the formation of the landscape; erosion, transportation, and deposition of sediments. These functions are controlled by the energy of the stream, and the energy of the stream is determined by the stream's gradient and discharge.

Types of Streams Perennial Streams - These streams always have flow. During dry weather, the flow of perennial streams is base flow, consisting of interflow and groundwater flow intercepted by the stream. Streams that feed from groundwater reservoirs are called effluent streams. Perennial streams and effluent streams are typical of humid regions.

Ephemeral Streams - These streams have flow only in direct response to effective precipitation. Ephemeral streams do not intercept ground-water flow and therefore have no base flow. Streams that feed water into groundwater reservoirs are called influent streams. Ephemeral and influent streams are typical of arid and semiarid regions.

Intermittent Streams - These streams have mixed characteristics, behaving as perennial at certain times of the year and ephemeral at other times. Depending on seasonal conditions, these streams may feed to or from the groundwater.

Run-Off

Run-Off Run-off means the draining or flowing off of precipitation from a catchment area through a surface channel then enters into a stream channel.

There are three main routes of which the water travels; Overland Flow Interflow Ground Water flow.

The Figure below shows a simple illustration of different routes of water travel

Overland Flow or Surface Run-Off Excess rainfall moves over the land surface to reach small channels. This Characteristic of runoff is called overland flow.

Interflow or Sub-Surface Flow This Characteristic defines rainfall or any external source of water that infiltrates the soil surface that moves laterally through upper layers of soil and returns to the surface at some location without entering the saturated zone.

Ground Water Flow Infiltrated water reaching saturated zone and moves through the soil as groundwater flow. It is also called base flow.

The following are the factors affecting flow characteristic of streams. Rainfall Characteristics Catchment Characteristics Climatic Factors

1. Rainfall Characteristics Magnitude Intensity Distribution of Time and Space and its Variability.

2. Catchment Characteristics Soil Type Vegetation Slope Geology Shape and Drainage Density

3. Climatic Factors Location