2.1. `floodestimation.entities` — Core components¶

This module contains the core components or entities, including Catchment, AmaxRecord etc.

Note that all entities are subclasses of floodestimation.db.Base which is an SQL Alchemy base class to enable saving to a (sqlite) database. All class attributes therefore are sqlalchemy.Column objects e.g. Column(Float), Column(String), etc. Attribute values can simply be set like normal, e.g. catchment.watercourse = “River Dee”.

2.1.1. `Catchment` — The catchment object¶

class floodestimation.entities.Catchment(location=None, watercourse=None)[source]¶

Catchment object include FEH catchment descriptors and additional information describing the catchment.

Example:

>>> from floodestimation.entities import Catchment, Descriptors
>>> catchment = Catchment("Aberdeen", "River Dee")
>>> catchment.channel_width = 1
>>> catchment.descriptors = Descriptors(dtm_area=1, bfihost=0.50, sprhost=50, saar=1000, farl=1, urbext=0}
>>> catchment.qmed()
0.2671386414098229

id¶: Gauging station number

country¶: Abbreviation of country, e.g. gb, ni.

channel_width¶: Width of the watercourse channel at the catchment outlet in m.

area¶: Catchment area in km²

point¶: Coordinates of catchment outlet as Point object

is_suitable_for_qmed¶: Whether this catchment can be used to estimate QMED at other similar catchments

is_suitable_for_pooling¶: Whether this catchment’s annual maximum flow data can be used in pooling group analyses

pot_dataset¶: Peaks-over-threshold dataset (one-to-one relationship)

comments¶: List of comments

location¶: Catchment outlet location name, e.g. Aberdeen

watercourse¶: Name of watercourse at the catchment outlet, e.g. River Dee

amax_records¶: List of annual maximum flow records as AmaxRecord objects

descriptors¶: FEH catchment descriptors (one-to-one relationship)

qmed()[source]¶

Returns QMED estimate using best available methodology depending on what catchment attributes are available.

Returns:	QMED in m³/s
Return type:	float

amax_records_start()[source]¶: Return first water year in amax records

amax_records_end()[source]¶: Return last year in amax records

record_length¶: Total number of valid AMAX records

2.1.2. `Descriptors` — A set of catchment descriptors¶

class floodestimation.entities.Descriptors(**kwargs)[source]¶

Set of FEH catchment descriptors.

This is the complete set of name = value pairs in the [DESCRIPTORS] block in a CD3 file. All other parameters are directly attributes of Catchment.

Descriptors are used as follows:

>>> from floodestimation.entities import Catchment
>>> catchment = Catchment(...)
>>> catchment.descriptors.dtm_area
416.56
>>> catchment.descriptors.centroid_ngr
(317325, 699832)

A simple constructor that allows initialization from kwargs.

Sets attributes on the constructed instance using the names and values in kwargs.

Only keys that are present as attributes of the instance’s class are allowed. These could be, for example, any mapped columns or relationships.

catchment_id¶: One-to-one reference to corresponding Catchment object

ihdtm_ngr¶: Catchment outlet national grid reference as Point object. Catchment.country indicates coordinate system.

centroid_ngr¶: Catchment centre national grid reference as Point object. Catchment.country indicates coordinate system.

dtm_area¶: Surface area in km² based on digital terrain model data

altbar¶: Mean elevation in m

aspbar¶: Mean aspect (orientation) in degrees

aspvar¶: Aspect variance in degrees

bfihost¶: Base flow index based on Hydrology of Soil Types (HOST) data. Value between 0 and 1.

dplbar¶: Mean drainage path length in km

dpsbar¶: Mean drainage path slope (dimensionless)

farl¶: Lake, reservoir or loch flood attenuation index

fpext¶: Floodplain extent parameter

ldp¶: Longest drainage path length in km

propwet¶: Proportion of time soils are wet index

rmed_1h¶: Median annual maximum 1 hour rainfall in mm

rmed_1d¶: Median annual maximum 1 day rainfall in mm

rmed_2d¶: Median annual maximum 2 day rainfall in mm

saar¶: Standard annual average rainfall in mm, 1961-1990 average

saar4170¶: Standard annual average rainfall in mm, 1941-1970 average

sprhost¶: Standard percentage runoff based on Hydrology of Soil Types (HOST) data. Value between 0 and 100.

urbconc1990¶: Urbanisation concentration index, 1990 data

urbext1990¶: Urbanisation extent index, 1990 data

urbloc1990¶: Urbanisation location within catchment index, 1990 data

urbconc2000¶: Urbanisation concentration index, 2000 data

urbext2000¶: Urbanisation extent index, 2000 data

urbloc2000¶: Urbanisation location within catchment index, 2000 data

urbext(year)[source]¶

Estimate the urbext2000 parameter for a given year assuming a nation-wide urbanisation curve.

Methodology source: eqn 5.5, report FD1919/TR

Parameters:	year (float) – Year to provide estimate for
Returns:	Urban extent parameter
Return type:	float

2.1.3. `AmaxRecord` — Annual maximum flow records¶

class floodestimation.entities.AmaxRecord(date, flow, stage=None, flag=0)[source]¶

A single annual maximum flow record.

Catchment.amax_records is a list of AmaxRecord objects.

Example:

>>> from floodestimation.entities import AmaxRecord
>>> from datetime import date
>>> record = AmaxRecord(date=date(1999,12,31), flow=51.2, stage=1.23)

catchment_id¶: Many-to-one reference to corresponding Catchment object

date¶: Date at which maximum flow occured

water_year¶: Water year or hydrological year (starts 1 October)

flow¶: Observed flow in m³/s

stage¶: Observed water level in m above local datum

flag¶: Data quality flag. 0 (default): valid value, 1: invalid value, 2: rejected record.

2.1.4. `PotDataset` — Peaks-over-threshold datasets¶

class floodestimation.entities.PotDataset(**kwargs)[source]¶

A peaks-over-threshold (POT) dataset including a list of PotRecord objects and some metadata such as start and end of record.

catchment_id¶: One-to-one reference to corresponding Catchment object

start_date¶: Start date of flow record

end_date¶: End date of flow record (inclusive)

threshold¶: Flow threshold in m³/s

pot_records¶: List of peaks-over-threshold records as PotRecord objects

pot_data_gaps¶: List of peaks-over-threshold records as PotDataGap objects

record_length¶: Return record length in years, including data gaps.

total_gap_length()[source]¶: Return the total length of POT gaps in years.

continuous_periods()[source]¶: Return a list of continuous data periods by removing the data gaps from the overall record.

2.1.5. `PotRecord` — Peaks-over-threshold records¶

class floodestimation.entities.PotRecord(date, flow, stage)[source]¶

A single peaks-over-threshold (POT) flow record.

Example:

>>> from floodestimation.entities import PotRecord
>>> from datetime import date
>>> record = PotRecord(date=date(1999,12,31), flow=51.2, stage=1.23)

catchment_id¶: Many-to-one reference to corresponding Catchment object

date¶: Date at which flow occured

flow¶: Observed flow in m³/s

stage¶: Observed water level in m above local datum

2.1.6. `PotDataGap` — Peaks-over-threshold data gaps¶

class floodestimation.entities.PotDataGap(**kwargs)[source]¶

A gap (period) in the peaks-over-threshold (POT) records.

A simple constructor that allows initialization from kwargs.

Sets attributes on the constructed instance using the names and values in kwargs.

Only keys that are present as attributes of the instance’s class are allowed. These could be, for example, any mapped columns or relationships.

catchment_id¶: Many-to-one reference to corresponding Catchment object

start_date¶: Start date of gap

end_date¶: End date of gap (inclusive)

gap_length()[source]¶: Return length of data gap in years.

2.1.7. `Comment` — Catchment comments¶

class floodestimation.entities.Comment(title, content)[source]¶

Comments on cachment contained in CD3 file. Each comment has a title (normally one of station, catchment, qmed suitability and pooling suitability) and content.

Catchment.comments is a list of Comment objects.

Example:

>>> from floodestimation.entities import Comment
>>> comment = Comment(title="station", content="Velocity-area station on a straight reach ...")

catchment_id¶: Many-to-one reference to corresponding Catchment object

title¶: Comment title, e.g. station

content¶: Comment, e.g. Velocity-area station on a straight reach ...

2.1.8. `Point` — Point coordinates¶

class floodestimation.entities.Point(x, y)[source]¶

Point coordinate object

Example:

>>> from floodestimation.entities import Point
>>> point = Point(123000, 456000)

Coordinates systems are currently not supported. Instead use Catchment.country = ‘gb’ etc.

2.1. floodestimation.entities — Core components¶

2.1.1. Catchment — The catchment object¶

2.1.2. Descriptors — A set of catchment descriptors¶

2.1.3. AmaxRecord — Annual maximum flow records¶

2.1.4. PotDataset — Peaks-over-threshold datasets¶

2.1.5. PotRecord — Peaks-over-threshold records¶

2.1.6. PotDataGap — Peaks-over-threshold data gaps¶

2.1.7. Comment — Catchment comments¶

2.1.8. Point — Point coordinates¶

2.1. `floodestimation.entities` — Core components¶

2.1.1. `Catchment` — The catchment object¶

2.1.2. `Descriptors` — A set of catchment descriptors¶

2.1.3. `AmaxRecord` — Annual maximum flow records¶

2.1.4. `PotDataset` — Peaks-over-threshold datasets¶

2.1.5. `PotRecord` — Peaks-over-threshold records¶

2.1.6. `PotDataGap` — Peaks-over-threshold data gaps¶

2.1.7. `Comment` — Catchment comments¶

2.1.8. `Point` — Point coordinates¶