Lachlan River (NSW)

Surface Water Dynamics Report

Calendar recurrence of annual peak and trough timing was not established (peak Kuiper p = 0.262; trough Kuiper p = 0.139; alpha = 0.05). Aseasonal means recurrence was not established, not that timing was proven uniform. Wet events and low-extent spells are reported; exact hydrological-year boundaries are withheld.

Aseasonal

hydrological regime
assessed seasonal strength

Not established

seasonality evidence
Kuiper p-values: peak=0.262; trough=0.139. Both reject 12-month uniformity (alpha = 0.05).

Event-Based

analytical route
how hydro-year boundaries were derived

0.0% zero-water months

observability
0 whole-zero years; 8/21 years support both peak and trough timing

hydrological years
Jan 2005 to Dec 2025; recurrence alpha=0.05; 14 detectable years, 19 timing-eligible years, 21 qualifying years.

Not defined

mean cycle length
withheld: no reproducible annual cycle

Not defined

Typical peak month
withheld: no reproducible annual cycle

Not defined

Typical trough month
withheld: no reproducible annual cycle

Not defined

well-observed years
withheld: no reproducible annual cycle

Not defined

point-identifiable boundary years
withheld: no reproducible annual cycle

wet events
episodes above the record's 75th percentile

55 mo

longest low-extent spell
longest continuous run below baseline

years without a wet event
out of 21 usable years

7.6%

average invalid/cloud cover
mean across 252 months of observations

Monthly Surface Water Extent

Seasonal Context

Wet Event Characterisation

A wet event begins once extent climbs above 0.5% (baseline 0.3% plus a margin sized to this record's own month-to-month noise) and continues until it falls back below 0.4% -- hysteresis, so a wobbling recession is not counted as several separate floods. Events shorter than 1 month(s) are dropped; episodes closer than 1 month(s) apart are merged into one.

Low-Extent Spells

A low-extent spell is a run of at least 2 consecutive months below 0.2% (baseline 0.3% minus a margin sized to the same noise scale), counted independently of wet events -- a catchment that never floods can still have long low-extent spells. About 39.7% of this record's months sit below that line, so a spell describes a sustained below-typical period, not an absence of water.

Yearly Cycle Details

Expand individual hydrological years to view monthly breakdowns and detailed statistics.

No hydrological-year cycles available.

Raw Data Browser

Filter and explore the monthly extent data directly.

Date	Phase	Hydro Year	Extent (%)	Invalid (%)	Data quality	Wet event	Low-extent spell