Small Ponds in Headwater Catchments Are a Dominant Influence on Regional Nutrient and Sediment Budgets. Issue 16 (31st August 2019)

• Record Type: Journal Article
• Authors: Schmadel, Noah M.; Harvey, Judson W.; Schwarz, Gregory E.; Alexander, Richard B.; Gomez‐Velez, Jesus D.; Scott, Durelle; Ator, Scott W.
• Is Part Of: Geophysical research letters. Volume 46:Issue 16(2019)
• Page Start: 9669
• Page End: 9677
• Publication Date: 2019-08-31
• Subjects: small ponds -- regional nutrient and sediment budgets -- river corridor -- ponded waters; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL083937
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Small ponds—farm ponds, detention ponds, or impoundments below 0.01 km 2 —serve important human needs throughout most large river basins. Yet the role of small ponds in regional nutrient and sediment budgets is essentially unknown, currently making it impossible to evaluate their management potential to achieve water quality objectives. Here we used new hydrography data sets and found that small ponds, depending on their spatial position within both their local catchments and the larger river network, can dominate the retention of nitrogen, phosphorus, and sediment compared to rivers, lakes, and reservoirs. Over 300, 000 small ponds are collectively responsible for 34%, 69%, and 12% of the mean annual retention of nitrogen, phosphorus, and sediment in the Northeastern United States, respectively, with a dominant influence in headwater catchments (54%, 85%, and 50%, respectively). Small ponds play a critical role among the many aquatic features in long‐term nutrient and sediment loading to downstream waters. Plain Language Summary: Reservoirs created by river damming have extensive impacts on downstream water quality but are not necessarily the most important elements of a diverse aquatic landscape. Many more small ponds have been constructed to serve important human needs ranging from farm irrigation in agricultural areas to flood control and trapping of nutrients and fine sediment in urban areas. The number of human‐influenced small ponds is projected to rise worldwide, yet their role in the delivery of nutrients and sediment from headwaters to oceans is currently unresolved. Here we used new data sets and found that small ponds are collectively responsible for trapping a substantial amount of the nutrients and sediment that are exported annually from headwaters. These findings support the need to jointly consider features such as urban detention ponds, farm ponds, and beaver ponds in managing headwaters to decrease long‐term nutrient and sediment loading to downstream waters and sensitive coastal areas. Key Points: Small ponds located in headwater catchments dominate nutrient and sediment retention compared to streams, rivers, lakes, and reservoirs Small ponds located directly adjacent to streams or away in upland positions have distinct effects on nitrogen, phosphorus, and sediment Finer‐scale small streams are minor net sources of phosphorus and major net sources of sediment where soil erodibility is high