Newswise — AMHERST, Mass. – A group of academics from the University of Massachusetts Amherst have released a recent report in the publication PLOS Water, concentrating on the Sudbury-Assabet and Concord watershed in eastern Massachusetts. The research associates modifications in land use to changes in water flow such as floods, drought, and runoff.
According to Timothy Randhir, a senior author of the paper and a professor of environmental conservation at UMass Amherst, "We reside within a watershed." He added that we are consistently transforming the environment, converting former forests into parking lots, roads, and residential areas, causing the landscape to shift from being hydrologically robust to one that moves water downstream.
However, it can be challenging to recognize the intricate connections between alterations in land use and changes in the hydrological cycle. For instance, a considerable portion of Massachusetts is currently experiencing a contradictory state in which drought during the summer comes after flooding in the spring. One would think that if there is adequate surplus water to cause street flooding in towns across the state, then there must be sufficient groundwater for drinking, lawn irrigation, and maintaining the water levels of rivers and lakes.
This is where adopting a watershed perspective becomes crucial. According to Randhir, "Every raindrop has two paths once it hits the ground. It can either flow over the land into a waterway or seep into the soil, gradually making its way down to the groundwater table." However, by paving extensive areas of land, filling up swamps and wetlands, and constructing river channels, we have made it significantly harder for rainwater to permeate the soil, resulting in a higher likelihood of drought. Simultaneously, all the runoff enters rivers and streams, which swells into a torrent as it moves downstream, fueled by even more runoff as it advances.
To make the connections between land use and hydrological impacts apparent and to anticipate these effects in the future, Randhir and his graduate student and first author Ammara Talib concentrated on the Sudbury-Assabet and Concord watershed in eastern Massachusetts, a region that encompasses rural and suburban areas of Boston. They entered historical data describing the changing land use into a model that predicted the trends for 2035, 2065, and 2100. Next, they input the outcomes of the land-use model into a hydrological model known as the Hydrological Simulation Program-FORTRAN.
Their findings revealed that by 2100, the overall forested area will decline by 51%, while impervious surfaces such as roads and parking lots will grow by 75%. As a result, annual stream flow will rise by 3%, while runoff will surge by a staggering 69% per year. This intensified runoff will lead to more topsoil and other sediments in the water (an increase of 54%), as well as a 12% increase in phosphorus and a 13% increase in nitrogen concentrations
Randhir states, "We can prepare for the future by taking a watershed-scale approach" through urban planning that includes sustainable and location-specific land-use practices. These may involve constructing rain gardens, using permeable pavement in vast parking lots, and implementing vegetated swales to decrease the speed of runoff.
Randhir highlights that "The watershed serves as a marker of the overall health of the ecosystem. The quality of life in any given region is contingent on how effectively the watershed is operating."
RSS