The briefing I received from Waikato Regional Council scientists has confirmed – yes – we have just had a record-breaking drought in Thames-Coromandel.
Rainfall
Our summer rainfall was about 20% of the average for 1981 – 2010
Drought index
The drought index for Thames-Coromandel shows a record drought, even more severe than the one in 2013
Monthly Rainfall
The gray shaded area shows the average for the past 30 years by month. As you can see in January February March, and April 2020 (blue bars) the monthly rainfall was tiny compared to the average, and considerably lower than in 2013 (pink bars). November and December 2019 were also below average.
Soil Moisture Deficit
Again, compared to the historical average the soil moisture deficit has been at extreme levels compared to the average for 25 February
River flows
The river flow for the Opitunui River near Whitianga was at record low levels for January, February, March, and April 2020. No surprise that Whitianga had severe water shortages.
Conclusion
- The 2020 drought was a region wide event
- record low precipitation, coupled with high temperatures led to low soil moisture and record low river flows
- six of the seven dry summers and over 100 years have occurred since 2008
Ecological damage
A lethal combination of heat, silted-up floodgates and degraded waterways has led to a deadly outbreak of botulism and a suspected toxic algal bloom on the Hauraki Plains
