Unsettled weather at the start of March brought hope that the very dry conditions gripping Otago might be breaking, but the rain did not continue and rivers and lakes reverted to earlier low flows and levels, Dave Stewart hydrological consultant for Raineffects, says.
The first 11 days of March were somewhat unsettled, with a series of fronts and troughs crossing the South Island from the west and southwest, bringing a period of heavy rain to the whole region.
‘‘It provided some hope to all farmers that it may be the start of the breaking of the very dry conditions that had gripped Otago for some months.''
However, the subsequent fronts and troughs did not bring good follow-up rains and by the end of March, rivers and lake levels had gone back to earlier levels, he said.
From March 10-17 and 22-28, anticyclones brought dry, warm conditions to most of the region, resulting in above-average temperatures and sunshine hours for the month.
A cold front on March 20-21 brought some rain to most of the region and helped a little in maintaining what growth was occurring on non-irrigated land.
The front on March 27-28 brought rain across much of the region but little fell in Central and North Otago, Mr Stewart said.
North Otago rainfall was well below average and pasture growth was mainly confined to irrigated land.
Total falls at the indicator sites (average monthly totals in brackets) were: Chain Hills, Omarama 25mm (32mm) 22% below average; Waikoura 20mm (52m) 62% below average; Oamaru Airport 29mm (54mm) 46% below average; Kauru, the Dasher 36mm (77mm) 52% below average; Palmerston 21mm (55mm) 62% below average.
Other rainfall totals in the month included: Stoneburn 31mm and Oamaru Township 22mm.
Significant falls during the month included: March 1-2, Omarama 15mm, Waikoura 15mm, Oamaru Airport 18mm, Oamaru Town 17mm, Islay Downs 31mm, Palmerston 20mm.
With no significant rainfall later in the month, rivers declined to low flows but did not fall as low as they did in February, he said.
Farmers reported by the end of the month that conditions were very dry with no growth on non-irrigated land.
In Central Otago, rainfall was close to average, with total falls: Lindis Crossing 41mm (48mm) 15% below average; Alexandra 33mm (33mm) average; Ranfurly 43mm (47mm) 9% below average; Tima 53mm (57mm) 7% below average.
Significant falls were March 1-2, Lindis Crossing 16mm, Alexandra 16mm, Hills Creek 24mm, Ranfurly 31mm; on 21 March, Lindis Crossing 23mm, Alexandra 13mm, Ranfurly 11mm.
Farmers reported that, apart form the beginning of the month, immediately following the heavy rain, grass growth on non-irrigated land stopped, Mr Stewart said. Rain was urgently needed before winter.
In Lakes Wanaka, Wakatipu and Hawea and surrounding areas, rainfall was well below average and lake levels fell to quite low levels.
Total falls were: Makarora Station 104mm (179mm) 42% below average; Hunter Valley Station 37mm (105mm) 64% below average; Hawea Flat 22mm (62mm) 64% below average; Routeburn Station 119mm (186mm) 36% below average; Queenstown 44mm (72mm) 39% below average.
Halfway Bay Station recorded 48mm for the month. Some of the heavier falls in this area included: March 1, Makarora Station 28mm, Glenfinnan 34mm; March 21 Glenfinnan 24mm, Routeburn Station 28mm, Queenstown 23mm; and March 27-28 Makarora Station 21mm, Glenfinnan 21mm, Routeburn Station 23mm.
Lakes Wanaka and Wakatipu began the month at about 0.1m below their average levels of 277.25m and 309.86m.
They rose a little as a result of the rain but then declined. By the end of the month, levels were at 276.93m and 309.72m, 0.4m and 0.25m below average respectively.
Lake Hawea rose slowly from 342.92m to 343.23m during the first half of the month as Contact Energy held outflows at close to minimum level. After that, releases for hydro generation from the lake saw it fall to 343.01m by the end of the month, 3m below full.
Farmers in the lakes headwaters reported that March was warm, with good grass growth. At the lower ends of the lakes, growth was very slow on non-irrigated land due to a lack of rainfall, Mr Stewart said.
In Strath Taieri, Lower Taieri and Dunedin rainfall varied from between 20% below average to 30% above average.
Total falls were: Garthmyl Middlemarch 40mm (50mm) 20% below average; Musselburgh Dunedin 75mm (70mm) 7% above average; Maungatua 84mm (64mm) 30% above average; Dunedin Airport 67mm (64mm) 30% above average; Pine Hill 70mm (86mm) 19% below average; Sullivans Dam 86mm (106mm) 19% below average.
Other rain gauge totals included: Ross Creek 77mm, Southern Reservoir 84mm.
Heavier falls included: March 1-2, Middlemarch 25mm, Musselburgh 61mm, Maungatua 47mm, Pine Hill 56mm, Dunedin Airport 38mm.
Farmers reported sufficient rainfall and warmth to allow good growth through most of the month, Mr Stewart said.
In South and West Otago, while conditions remained quite dry in some parts, most received above average rainfall for March.
Total falls were: Tuapeka Mouth 70mm (68mm) 3% above average; Balclutha 102mm (59mm) 73% above average; Waikoikoi 111mm (82mm) 36% above average; Moa Flat 91mm (68mm) 33% above average; Clarks Flat 75mm (64mm) 16% above average.
At all sites, the heaviest falls occurred at the beginning of March. On March 1-3, Tuapeka Mouth recorded 42mm, Balclutha 86mm, Waikoikoi 64mm, Slopedown 46mm, Moa Flat 54mm, and Clarks Flat 47mm; March 11 Waikoikoi 20mm, Slopedown 18mm, Moa Flat 12mm.
Farmers generally reported a good month for growth, with the odd area still a bit dry for growth.