Small Reservoir Distribution, Rate of Construction, and Uses in the Upper and Middle Chattahoochee Basins of the Georgia Piedmont, USA, 1950–2010

John Jones,Amber Ignatius

doi:10.3390/ijgi3020460

Abstract

Construction of small reservoirs affects ecosystem processes in numerous ways including fragmenting stream habitat, altering hydrology, and modifying water chemistry. While the upper and middle Chattahoochee River basins within the Southeastern United States Piedmont contain few natural lakes, they have a high density of small reservoirs (more than 7500 small reservoirs in the nearly 12,000 km2 basin). Policymakers and water managers in the region have little information about small reservoir distribution, uses, or the cumulative inundation of land cover caused by small reservoir construction. Examination of aerial photography reveals the spatiotemporal patterns and extent of small reservoir construction from 1950 to 2010. Over that 60 year timeframe, the area inundated by water increased nearly six fold (from 19 reservoirs covering 0.16% of the study area in 1950 to 329 reservoirs covering 0.95% of the study area in 2010). While agricultural practices were associated with reservoir creation from 1950 to 1970, the highest rates of reservoir construction occurred during subsequent suburban development between 1980 and 1990. Land cover adjacent to individual reservoirs transitioned over time through agricultural abandonment, land reforestation, and conversion to development during suburban expansion. The prolific rate of ongoing small reservoir creation, particularly in newly urbanizing regions and developing counties, necessitates additional attention from watershed managers and continued scientific research into cumulative environmental impacts at the watershed scale.

Highlights

Reservoirs are important hydrologic features affecting numerous aspects of the aquatic and riparian environment [1]
While definitions between pond and reservoir vary regionally and by discipline [2], here we define reservoir as a water body created through artificial impoundment for the storage and regulation of water
The quantity of reservoirs increased from 1950 to 2010 in all study areas with a total increase from 19 to 329 reservoirs (Table 2). This pattern was true across all watershed categories with the number of agricultural watershed reservoirs increasing from three to 12, forested watershed reservoirs increasing from one to 21, rural developed watershed reservoirs increasing from one to 15, and urban developed watershed reservoirs increasing from 17 to 281 (Figure 3)

Summary

Introduction

Reservoirs are important hydrologic features affecting numerous aspects of the aquatic and riparian environment [1]. Reservoirs modify downstream sediment loads, water chemistry, and nutrient regimes in complex ways [3,4,5]. Reservoirs capture suspended sediment, nutrients, and pollutants by slowing water velocities and allowing these inputs to drop out of the water column and become stored in the benthos [6,7]. Downstream reaches become sediment-starved and exhibit altered geomorphology while the reservoirs in-fill and lose water storage capacity [8,9,10]. The sedimentation, which is commonly rich in nutrients and pollutants, requires ongoing management [11,12]. Reservoirs may contribute to downstream nutrient levels if they are managed for recreational fishing and are fertilized to promote algae growth and sustain populations of stocked fish [13,14]

Results

Discussion

Conclusion