SURFACE WATER (STREAM)

REPORTED BY : REY C. AUDITOR

BSCE 5-2

Definition of stream Parts of a stream Sources of stream Types of stream Characteristics of stream Importance of stream Common problems of stream Measurement of streamflow Interaction of stream to groundwater

REPORT OUTLINE :

is a body of running water moving under the influence of gravity to lower levels in a narrow clearly defined natural channel.

STREAM

BAR A shoal that develops in a stream as

sediment is deposited as the current slows or is impeded by wave action at the confluence. BIFURCATION

A fork into two or more streams. CHANNEL

A depression created by constant erosion that carries the stream's flow.

PARTS OF A STREAM

CONFLUENCEThe point at which the two streams merge. If

the two tributaries are of approximately equal size, the confluence may be called a fork. FLOODPLAIN

Lands adjacent to the stream that are subject to flooding when a stream overflows its banks. GAUGING STATION

A point of demarcation along the route of a stream or river, used for reference marking or water monitoring.

HEADWATERSThe part of a stream or river proximate to its

source. The word is most commonly used in the plural where there is no single point source. NICK POINT

The point on a stream's profile where a sudden change in stream gradient occurs. MOUTH

The point at which the stream discharges, possibly via an estuary or delta, into a static body of water such as a lake or ocean.

POOLA segment where the water is deeper and

slower moving. RIFFLE

A segment where the flow is shallower and more turbulent. RIVER

A large natural stream, which may be a waterway.

RUNA somewhat smoothly flowing segment of

the stream. SOURCE

The spring from which the stream originates, or other point of origin of a stream. SPRING

The point at which a stream emerges from an underground course through unconsolidated sediments or through caves.

STREAM BEDThe bottom of a stream.

STREAM CORRIDORSteam, its floodplains, and the

transitional upland fringe. WATERFALL

The fall of water where the stream goes over a sudden drop called a nickpoint. WETTED PERIMETER

The line on which the stream's surface meets the channel walls.

Streams typically derive most of their water from precipitation in the form of rain and snow.

Some precipitated water proceeds to sink into the earth by infiltration and becomes groundwater, much of which eventually enters streams.

Some creeks may start from ponds or lakes.

SOURCES OF STREAM

HEADWATER STREAMSare the beginnings of rivers, the uppermost streams

in the river network furthest from the river's endpoint or confluence with another stream.

YEAR-ROUND STREAMS (PERENNIAL) typically have water flowing in them year-round.

Most of the water comes from smaller upstream waters or groundwater while runoff from rainfall or other precipitation is supplemental.

TYPES OF STREAM

SEASONAL STREAMS (INTERMITTENT) flow during certain times of the year when

smaller upstream waters are flowing and when groundwater provides enough water for stream flow.

RAIN-DEPENDENT STREAMS (EPHEMERAL) flow only after precipitation. Runoff from

rainfall is the primary source of water for these streams. Like seasonal streams, they can be found anywhere but are most prevalent in arid areas.

RANKING

A stream of the first order is a stream which does not have any other recurring or perennial stream feeding into it.

When two first-order streams come together, they form a second-order stream.

When two second-order streams come together, they form a third-order stream.

CHARACTERISTICS OF STREAM

GRADIENTThe gradient of a stream is a critical factor in

determining its character and is entirely determined by its base level of erosion.

MEANDERMeanders are looping changes of direction of

a stream caused by the erosion and deposition of bank materials. Typically, over time the meanders gradually migrate downstream.

PROFILEStreams are said to have a

particular profile, beginning with steep gradients, no flood plain, and little shifting of channels. STREAMLOAD

Streams can carry sediment, or alluvium.

Clean drinking water Flood and erosion protection Groundwater recharge Pollution reduction Wildlife habitat Economic importance

-fishing -hunting-agriculture - manufacturing

IMPORTANCE OF STREAM

BANK INSTABILITYis characterized by sparse riparian vegetation

and excessively eroding cut banks, which may slough into the active stream channel. SEDIMENTATION

Bank instability and erosion frequently results in excessive sediment inputs into stream channels.

COMMON STREAM PROBLEMS

CHANNEL ALTERATIONChannel alteration from bulldozing,

dredging, and construction causes severe disturbance to the channel and to riparian vegetation.

REDUCTION OR LOSS OF RIPARIAN AREA

Reduction of riparian areas that leads to a loss of bank stabilizing plants, formation of an over-widened channel and increased sedimentation.

IRRIGATION CANALS AND DIVERSIONS

In addition to decreasing in stream flow, water diversions can block migration of fish.

IMPACTS FROM MINING

Mining operations can severely disturb the landscape and/or stream channel water quality.

Other impacts from mining are acidification of streams from acid mine drainage or metal contamination of the stream

Surface water flow is simply the continuous movement of water in runoff or open channels.

Measurement of surface water flow is an important component of most water quality monitoring projects.

Flooding, stream geomorphology, and aquatic life support are all directly influenced by streamflow, and runoff and streamflow drive the generation, transport, and delivery of many nonpoint source (NPS) pollutants.

MEASUREMENT OF SURFACE WATER FLOW (STREAMFLOW)

Discharge, defined as the rate of flow or the volume of water that passes through a channel cross section in a specific period of time.

The depth of flow (m or Ft.) is most commonly measured as stage, the elevation of the water surface relative to an arbitrary fixed point.

Stage is important because peak stage may exceed the capacity of stream channels, culverts, or other structures, while both very low and very high stage may stress aquatic life.

Problem assessment Watershed project planning Assessment of treatment needs Targeting source areas Design of management measures Project evaluation.

PURPOSES OF FLOW MEASUREMENT

FUNDAMENTAL MEASUREMENTS

Discharge is typically calculated as the product of velocity and cross-sectional area.

Surface water velocity is the direction and speed with which the water is moving, measured in feet per second (ft/s) or meters per second (m/s).

The cross-sectional area of an open channel is the area of a slice in the water column made perpendicular to the flow direction.

1. BASIC PRINCIPLES OF DISCHARGE MEASUREMENT

Friction caused by the rough channel surfaces slows the water near the bottom and sides of a channel

To deal with the variability in stream velocity, studies support several general rules of thumb:

Maximum velocity occurs at 5–25% of the depth, this percentage increases with increasing stream depth.

Mean velocity in a vertical profile is approximated by the velocity at 0.6 depth.

Mean velocity in a vertical profile is more accurately represented by the mean of the velocities at 0.2 and 0.8 depth.

The mean velocity in a vertical profile is 80–95% of the surface velocity, the average of several hundred observations being 85%.

Determining the cross-sectional area of a flowing stream usually involves measuring water depths at a series of points across the stream and multiplying by the width of the stream within each segment represented by the depth measurement. The areas are summed to determine the entire cross-sectional area.

Stream stage is an important parameter of streamflow measurement.

Stage is often measured relative to a fixed point using a staff gage, a rigid metal plate graduated in meters or feet attached to a secure backing and located in a part of the stream where water is present even at low flows.

Stage measurements are taken by simply noting the elevation of the water surface on the graduations of the staff gage.

2. STAGE MEASUREMENT

Simple manual stage measurements can give a rough qualitative indication of the magnitude of discharge .

A stage-discharge relationship is an equation determined for a specific site that relates discharge to stage, based on a linear regression of a series of concurrent measurements of stage and discharge.

3. STAGE-DISCHARGE CURVES

FLOW MEASUREMENT METHODS

Peak stage is essential to know in flood planning, especially for flood frequency statistics, floodplain management, and design/protection of structures.

Peak stage can be observed by several informal means:

-Direct observations made during high flow events can record the maximum height of water on buildings or other structures.

-Using specialized crest gages, 2-inch diameter galvanized pipe containing a wood staff held in a fixed position in relation to a reference.

1. PEAK STAGE MEASUREMENT

Planning for a watershed project may require an estimate of total annual discharge from an ungagged watershed.

Such an estimate can be made simply using data from a nearby stream gage with a good historical record.

2. ESTIMATION OF ANNUAL DISCHARGE

3.1 MANNING’S EQUATIONDischarge may be computed based on a

slope-area method.

3. INSTANTANEOUS FLOW MEASUREMENT

FOR ENGLISH SYSTEM

Hydraulic radius is defined as the cross-sectional area divided by the wetted perimeter (the distance around the stream bed cross section that is under water).

FOR METRIC SYSTEM

Application of the Manning equation requires a straight stream reach between 200 and 1000 ft. (61–305 m) in length.

Slope of the water surface is determined from accurate measurements of stage at the upstream and downstream ends of the reach referenced to a common fixed point.

3.2. DIRECT MEASUREMENTa. Volumetric measurement

-simply measure the time required to fill a container of known volume.

b. Dilution methods-consist of adding a concentrated tracer solution (salt or dye) of known strength to the stream and by chemical analysis determining its dilution

c. Weirs and flumes

-a structure that water flows through or over that has a known relationship between stage and flow. - Weirs are essentially dams built across an open channel over which water flows through a specially shaped opening or edge.

- Flumes are specially shaped open channel flow sections that restrict the channel area, resulting in increased velocity and a change in water level as water flows through a flume.

d. Area-velocity technique -The most common method of

measuring discharge in open channels is by measuring the cross-sectional area and the mean water velocity.

The interaction takes place in three basic ways:

- streams gain water from inflow of ground water through the streambed.

- streams lose water to ground water by outflow through the streambed.- both, gaining in some reaches and

losing in other reaches.

INTERACTION OF GROUNDWATER AND STREAM

the altitude of the water table in the vicinity of the stream must be higher than the altitude of the stream-water surface.

can be determined from water-table contour maps because the contour lines point in the upstream direction where they cross the stream.

GAINING STREAM

the altitude of the water table in the vicinity of the stream must be lower than the altitude of the stream-water surface.

can be determined from water-table contour maps because the contour lines point in the downstream direction where they cross the stream.

LOSING STREAM

GAINING STREAM

LOSING STREAM

MIKI’S STREAM IN CAPOOCAN, LEYTE

CAPOOCAN, LEYTE

LIGNON HILL PARK STREAM, BICOL

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