Water World: Stormwater, Flooding, and Living in a Watershed in the Era of Climate Change and Extreme Weather Events With another forecast of heavy rain predicted for the tristate area this week, we are again reflecting on our role as land stewards to manage stormwater responsibly. We continually ask ourselves: what is the source of the problem, and how can we address it on a residential scale? What are our practical options for drainage solutions in our home landscapes? Even Death Valley is flooding! Wow, that’s got to tell you something! Twelve feet of snow in the Sierras is not unheard of or even abnormal. So, what is natural in our northeast watersheds, what can we expect? Early spring flooding can more detrimental, for most plants are still dormant and unable to absorb the excess water. Unchecked Development Impacts the Hydrologic Cycle Our relentless expansion and development of each vacant lot and former green space is the main ingredient in our stormwater diaspora. Developed land contains impervious space – asphalt, stone, concrete, roofs – that does not infiltrate stormwater, but rather, accelerates the runoff and contaminates it with pollutants from the building materials. Without intervention, the stormwater runoff floods our waterways, ultimately reaching the ocean instead of recharging our aquifers. When there is no place for stormwater to go, it pools in parking lots, driveways, and lawns until it eventually re-enters the atmosphere via evaporation. More and more stormwater enters the hydrologic cycle via evaporation, especially in highly developed areas. Instead of being absorbed by plant roots or percolating into aquifers, pooling stormwater takes the express route to the clouds, where they quickly become over saturated and start to precipitate again. The cycle continues. Oil and gas pollution is easily identified as a iridescent / shiny surface on water bodies. Our land development and manipulation are affecting the natural hydrologic cycle. Climate change is driving more extreme storm events, and our collectively inadequate stormwater management is exacerbating the problem. We are jeopardizing our most precious resource – fresh water – that when left unchecked, jeopardizes our second most precious resource: soil. Stormwater runoff causes soil erosion, and topsoil takes 500 – 1,000 years to generate 1” of depth; it is not renewable in our lifetime. Duck Weed invades a freshwater pond after rains washed nutrients from the newly-fertilized surrounding lawn into the pond. An example of what not to do. Furthermore, stormwater runoff that collects nutrients from garden or agricultural fertilizers is contributing to nutrient pollution in our oceans and harming coral reefs. Nutrient pollution in oceans disrupts calcification rates – the ability for coral reefs to expand – because it is harder for reef builders to access the necessary nutrient building blocks when there is excess nitrogen and phosphorous in the water. These conditions favor seaweed growth, which further competes with coral reef expansion. Irregular Seasonal Weather Patterns Disrupt Natural Stormwater Systems In New York, Connecticut, and New Jersey, we used to experience weather patterns which featured a mud season in March, followed by mild spring temperatures and moderate rainfall, followed by a drought or dry season, typically summer. Then, winter would be a dormant season, cold enough to suppress insects, disease, and invasive plants, as well as recharge the environment with snow and the positive electric charge, described as Farmer’s Fertilizer. The past few years have been much less predictable. Last year, we experienced a drought in early spring – catastrophic timing since spring is when plants need rainwater the most to push out new leaves and buds after winter dormancy. Plants were stunted by the drought in early spring last year, and then shocked by late spring and summer rains. Winter now rarely gets cold enough to snow – instead winter rains rip through our landscape while deciduous trees and shrubs are dormant and less adept at absorbing stormwater. Snow is much more effective at delivering nitrogen to plants in a slow trickle as it melts. Flooding creeps up from an adjacent wetland during a week long rain event. Winter rains also contribute to soil compaction. A gallon of water weighs eight pounds. Rain falling on lawn is especially effective at compacting the soil, since turf grass has shallow roots and cannot create air pockets deeper in the soil strata. As soils become more compact, their ability to transport stormwater is reduced, and water pools in the soil. These longer periods of saturation mean oxygen is less available to soil microbes, who may switch their fuel from oxygen to nitrogen. As a result, denitrification occurs in the soil (reducing plant-available nitrogen), and organic matter will be slower to decompose. By not managing stormwater correctly, we are contributing to anoxic soil conditions and changing the very soil biology that allows plants to thrive. Most of our native plants in the northeast are upland plants, adapted to good drainage and minimal pooling in the soil. Stormwater and soil mismanagement are inadvertently affecting which native plants will thrive, and ultimately contributing to biodiversity loss. Stormwater management solutions we often implement for our clients. management solutions we often implement for our clients. Landscape Drainage Solutions for Homeowners As homeowners, it is essential that we are pro-active in addressing stormwater in our landscapes. As landscape designers, we have many tools in our toolbox to address landscape drainage solutions. Developing a stormwater management plan requires careful observation and analysis of the surrounding watershed and soil conditions. Our previous blog details how to analyze your property for stormwater patterns, and lists solutions we often deploy for our clients. We need to be realistic and creative in our thinking of how best to utilize one of nature’s greatest natural resources. Feel free to contact us if you think we can be of service in improving the health and appearance of your landscape environment. — Green Jay Landscape Design Where Design Meets Ecology 914-560-6570
