Lead Scientist: Karen Prestegaard
Associate Professor
Department of Geology
Many communities are experiencing storm events of increased intensity, which can result in flooding, erosion, and water quality degradation. In some regions, increases in precipitation intensity are accompanied by larger gaps between precipitation events. In summer months, precipitation gaps can lead to flash droughts, which are intense, short-term droughts driven by only a few weeks to months of little rainfall combined with high temperatures. Flash droughts can drive significant decreases in streamflow and impact agricultural production.
The existing infrastructure in towns and cities is becoming unsuitable to store or convey runoff from intense storm events. Changes in both amounts and timing of precipitation could affect stream baseflow and possibly water resources for cities like Baltimore, College Park, and Washington D.C. that rely on rivers as water sources. Our current understanding of risks associated with floods and droughts is based on the previous 100+ years of record. With changes in storm and drought intensity, these databases and the statistics they provide are less useful in the prediction of future events and risks. An increase in stormwater runoff, particularly from urban areas, can also carry high flows, sediment, and contaminants to downstream estuaries. Convergence of storm surge, sea-level rise, and river flood levels in coastal urban areas can significantly increase flood risks.
Our Work
At CRN, we research the links among precipitation, stream baseflow, stormwater runoff, and evapotranspiration in forested, agricultural and urban catchments in Maryland and the mid-Atlantic region. We placed gauges in small, urban streams selected to represent areas with varying amounts of urbanization and geological characteristics. These gauges are used to determine how rapidly streams rise in response to storm events, the frequency of stream bed erosion, and the amount and duration of low flow events. We use these data and data from streams gauged by the USGS to quantify flow depths and response times during floods for streams with different drainage basin characteristics (area, amount of urbanization, etc.). Although we are focusing on Maryland, the research and tools we develop are applicable to other regions of the U.S. that experience short duration, intense storm events.
We are also examining changes in precipitation patterns across the U.S. to determine shifts in the seasonality and gaps between precipitation events may be changing. The length of gaps between precipitation events, particularly during the growing season can stress vegetation, affect evapotranspiration rates, and affect groundwater recharge and stream baseflow. Identifying and mapping regions that are experiencing changes in the distribution of precipitation can be used to identify geographic regions that are affected by these changes in the timing of precipitation and to evaluate whether these changes in precipitation are affecting streamflow. The goal is to provide information to decision-makers on changes in precipitation and stream discharge that can be incorporated into decisions about water allocation, an increasing concern in a region where water demand is increasing.
We intend to provide tools that can be used to anticipate short term and long-term changes in floods and water supply. Adaptation to these changes could include decisions on locations for urban development, forest management,and identification of streams that have short response times to intense storm events.