What is the catchment equation?

The long-term water balance equation for a catchment is P = Q + AET + GW + DS, with all terms expressed in mm/year, where P is Precipitation, Q is Runoff, AET is actual evapotranspiration, GW is exchange with groundwater aquifer and DS is change in soil storage.

What is the formula for catchment area?

At any point along this third slope line, a contour line can be constructed to the edges of the stream tube, and specific catchment area can be calculated as a = A/w using the area A above the contour line and length w of the contour line.

How is catchment area calculated?

These are usually defined by the distance from the school where the last pupil was offered a place in the previous school year. This can increase or decrease each year meaning that the catchment area can vary from year to year.

What is the equation for the catchment water balance?

The water balance of a catchment is composed of the elements precipitation (P), runoff (R), evaporation (E), and storage changes (δS). Whereas all other variables are based on meas- urements, evaporation must be determined by means of the following equation: E = P – R ± δS.

How do you calculate catchment size?

What is a Catchment Area and how does it work?

What is the formula for calculating rainwater?

To calculate how much rainwater can be harvested, multiply your rainfall (mm) by your roof surface area (m²) being used to catch rainwater. The resulting number represents how many litres of water you can expect to collect.

How do you calculate catchment slope?

catchment slope would be = (Difference in high & Low elevation)/Longest flow path length. The flow path is considered along the path by which water flows from upstream to downstream till it reaches the node-manhole / catch basin for SWMM solver.

How do you calculate water availability?

The water availability methodology defines three types of expected demands: (1) Storage, (2) Consumptive uses, and (3) In-stream demands. Then water availability can be defined in this equation: WA = QNSF – ST – CU – IS.

What is catchment water yield?

A catchment's water yield is a fundamental problem in hydrology, referring to the volume of water available at the catchment outlet over a specified period of time. The yield is expressed for monthly, seasonal, or annual periods.

What is the water runoff equation?

The Rational Formula is expressed as Q = CiA where: Q =Peak rate of runoff in cubic feet per second C =Runoff coefficient, an empirical coefficient representing a relationship between rainfall and runoff.

What is catchment size?

A catchment area is the geographic area for which a facility attracts clients or customers. The size and shape of a catchment area will depend on how accessible a facility is and how far it is from alternative facilities.

What is the catchment area ratio?

Comment: A ratio of approximately 3:1 is common and widely appropriate. i.e. The catchment area must be approximately twice as large as the cultivated area. Comment: Ratios are always lower for microcatchment systems due to a higher efficiency of water use and a higher runoff coefficient.

What is an example of a catchment area?

For example, a school catchment area is the geographic area from which students are eligible to attend a local school. When a facility's capacity can only service a specific volume, the catchment may be used to limit a population's ability to access services outside that area.

How do you calculate the area of a watershed?

Graph Paper Method (more accurate) Another way to calculate the size of the watershed is to trace the outline of your watershed on graph paper. Each square is 1/4 inch. Knowing this, convert it to the map's scale to determine the area of one square. For example if: 0.5 inches = 1000 feet, then 0.25 inches = 500 feet.

How do you calculate river yield?

River water yield is measured as stream flow or discharge in cubic metre per second (m3/s, volume over a period of time), along a defined stream profile. This yield is contribution of water from all sources upstream of that point in the river and the catchment contribution.

What is 75% dependable yield of a catchment?

Thus, 75% dependable annual yield is the value that can be expected to be equalled to or ex- ceeded 75% times (i.e. on an average 15 times in a span of 20 years). Similarly, 50% dependable yield is the annual yield value that is likely to be equalled or exceeded 50% of times (i.e. on an average 10 times in 20 years).

What is catchment area and water flow?

A catchment is an area of land, usually surrounded by mountains or hills, over which water flows and is collected. Within a catchment, water runs by gravity to the lowest point. The water is called surface runoff if it stays on the top of the land or groundwater flow if it soaks into the ground.

How do you calculate water content percentage?

Subtract the dry weight from the wet weight. Divide this number by the wet weight. Multiply by 100 to get percent moisture.

What is the catchment area of rainwater?

1. Catchments: The catchment of a water harvesting system is the surface which directly receives the rainfall and provides water to the system. It can be a paved area like a terrace or courtyard of a building, or an unpaved area like a lawn or open ground.

What is catchment slope?

The average catchment slope is consequently defined as the average slope perpendicular to the nearest contour line at each grid point.

What is the catchment area runoff?

Catchment runoff and infiltration is water from precipitation, snow and ice melt, irrigation and soil moisture storage that is not consumed by evapotranspiration or losses to increased soil moisture. Catchment Runoff can also be designated as the headflow to a river.

How do you calculate rainwater runoff?

Calculate your annual runoff: Take the area of your roof number x inches of rain per year (Bothell is around 36 inches) x . 62 =gallons per year.

How do you calculate rainwater flow rate?

Let the rainfall rate (r) = 75mm per hour. Your run off rate (q) = rx/3600 This gives the maximum litres of rainfall per second expected. Calculate the maximum run rate required by the gutter taking into consideration the position of the outlet in the run.

How do you calculate rainwater property runoff?

What does catchment mean in hydrology?

Catchments are areas of land where runoff collects to a specific zone. This movement is caused by water moving from areas of high energy to low energy due to the influence of gravity. Catchments often do not last for long periods of time as the water evaporates, drains into the soil, or is consumed by animals.