Listen: Rain Brings New Worries To Burned Areas In Australia
"Rain in the forecast for the east coast of Australia. And that's good news for firefighters still fighting blazes near some of the country's largest cities but ran after after fires can also create problems can even be dangerous and Beers Rebecca Hersher. Has This report when I called pattern. I'm in this week. He was in Melbourne walking outside. And I could hear the wind through the phone for smokey. We are expecting thunderstorms says a lot. More Humid Nyman is a forest hydrologist. He studies is how drought and wildfires can affect drinking water supplies and while the rain in the Australian forecast is a good thing. The thunderstorms worry. Him Is this a lot of Raines. Spread out over six months. That's a good outcome if there are short. Intense bursts of rainfall made through thunderstorms. Those are the ones that are problematic. Nick problematic because thunderstorms are more likely to drop a lot of rain in a short amount of time and areas. That burned can't absorb a lot of water for a couple of reasons. I wildfire removes vegetation which means that. The rainfall hits the soil directly. Second the vile fire heats the soil which causes something called water-repellent exellency or hydrophobia city. Which means that doesn't absorb into the soil so most of the rain becomes surface runoff. That runoff can sweep the soil and ash downhill hill and into streams and lakes. If a lot of sediment gets into reservoirs. The water gets really cloudy. And it can't be sterilized which means people can't drink it right now. The biggest drinking water concerns or for the areas around Canberra and Sydney water officials of setup filters at the reservoir that provides Sydney with the majority of its water to trap sediment and intense rain after fires can also be dangerous. A prime example. I'm and says is what's happened in California in recent years John. McNeil is the assistant. Didn't fire chief for Ventura County California. An area that has a similar landscape to many of the places that are burning in Australia in two thousand thirteen. A wildfire started in the hills there. Yeah it was called. The Springs Fire Wind caused the fire to burn hot and fast removing most of the vegetation and leaving the soil. Hard and Ashi at the base of the burnt hills were about two to three hundred homes. There's a small kind of retirement. Enclave of single family dwellings below the area that burn and year after the fire. There was a rainstorm voluntary. Evacuations tonight in Camarillo for people living near the hillside burn. Last year spring fire. The rain fell on hard soil. There were no plans to hold the dirt in place. Mud and rocks came loose and sped downhill the high impact areas it just completely leveled leveled the homes there would be some walls standing and then it was just completely sheared off from the debris and pretty sizeable rocks. That were coming down. Luckily people had evacuated evacuated in time. No one was killed. The risk of debris flows is rising in parts of California and Australia because of climate change and because of housing development relevant patterns. Hotter weather is drying out plants and soil exacerbating drought in making intense wildfires. More likely people are also building homes and and wildfire prone areas and as the earth gets hotter extreme. Rain is getting more common in Australia. The forest hydrologist Petr Nyman has found that debris flows are already getting more frequent and severe in the southeastern part of the country. That's where this year's fires are burning. The rainfall over the next six six months is going to be critical if there's a storm than they might be really widespread issues across the whole east coast of Australia. All of this requires a quick period habit for emergency officials from fighting the fires to protecting homes and water supplies from the quenching rains. Rebecca Hersher N._p._R. News."