Hindmarsh Shire Council

Hindmarsh Shire Council has towns that are subject to stormwater and riverine flooding. Towns that are impacted by stormwater flooding include Jeparit, Dimboola, Rainbow and Nhill.

Hindmarsh Shire has a long history of riverine flood events. Towns impacted by riverine flooding include Jeparit and Dimboola.

While flood events within the Hindmarsh Shire have been frequent over the last decade, the frequency of flood events has reduced since 1996.

Prior to 1996 flood events in the Wimmera River occurred on average once every four years. Water diversion to storages in the upper catchment of the GWMWater stock and domestic water supply system has significantly reduced flooding in Dimboola, Jeparit and the downstream terminal lakes.

Given these storages have the capacity (770,000 ML) to capture a significant proportion of high flows over a long period, water diversion to these storages has significantly reduced the frequency and magnitude of flooding in Dimboola, Jeparit and downstream terminal lakes, Lake Hindmarsh and Lake Albacutya.

The most significant recent flood event was recorded in 2011.

The major waterways within the Hindmarsh Shire Council are:

• Wimmera River
• MacKenzie River
• Norton Creek, Sandy Creek, Darragan Creek
• Datchak Creek

Further information on the flood history of the area can be found in the Hindmarsh Shire Council Flood  Emergency Plan.

Are you at risk of flood?

Dimboola is at risk of riverine flooding when the Wimmera River overflows its banks and flows into the southern and western areas of the town.

Riverine flooding usually occurs after a period of heavy, intense rainfall on already wet ground. The town is also at risk of flash flooding when intense rainfall overwhelms the local stormwater drainage system.

The Walmer Gauge, located near Horsham, approximately 35 kilometres upstream (south) of Dimboola, provides an early indication of flood impacts in Dimboola.

When flood heights exceed the major flood level (3.6 metres) at Walmer, flood water can be expected to breakout of the river at Dimboola and impact low-lying areas of the town one and a half to two days later.

Initially floodwater flows into the depression running from Park Street to Wimmera Street, and through the open space adjacent to the football grounds.

When the Wimmera River is in flood, town stormwater cannot drain into the river, increasing the flood risk from storms. Levees and floodways help to reduce the impacts of flooding in low-lying areas of south-west Dimboola during minor floods. Floods higher than minor flood level (at the Upstream Dimboola gauge) may result in water overtopping the levees and flooding northern parts of the town.
 

The map to the right shows expected flooding in Dimboola for a 1% Annual Exceedance Probability.

Are you at risk of flood

Jeparit and surrounding areas are at risk of flooding due to their location on the floodplain of theWimmera River.

The earliest indicator of flooding in Jeparit is when water breaks out of the Wimmera River near the Sir Robert Menzies Park. Jeparit has two levees, one near the football club (Sands Avenue) and one near the museum (Dimboola-Rainbow Road). These were constructed following flooding in 1956.

These levees provide minimal protection to the Jeparit township. However, it is important to remember that no two floods are the same and factors such as the depth of w ter in Lake Hindmarsh, and ground dryness, can influence the extent of flooding on Jeparit. Properties located on low-lying sections of Charles Street, Jeparit East Road, Riverside Street, Roy Street, Scott Street, Tullyvea Street and Nhill-Rainbow Road are the most vulnerable to flooding.

The table to the right shows Wimmera River flood levels at the Upstream Dimboola Gauge.