Linking Land Cover and Water Quality in New York City’S Water Supply Watersheds

Abstract

The Catskill/Delaware reservoirs supply 90% of New York City's drinking water. The City has implemented a series of watershed protection measures, including land acquisition, aimed at preserving water quality in the Catskill/Delaware watersheds. The objective of this study was to examine how relationships between landscape and surface water measurements change between years. Thirty-two drainage areas delineated from surface water sample points (total nitrogen, total phosphorus, and fecal coliform bacteria concentrations) were used in step-wise regression analyses to test landscape and surface-water quality relationships. Two measurements of land use, percent agriculture and percent urban development, were positively related to water quality and consistently present in all regression models. Together these two land uses explained 25 to 75% of the regression model variation. However, the contribution of agriculture to water quality condition showed a decreasing trend with time as overall agricultural land cover decreased. Results from this study demonstrate that relationships between land cover and surface water concentrations of total nitrogen, total phosphorus, and fecal coliform bacteria counts over a large area can be evaluated using a relatively simple geographic information system method. Land managers may find this method useful for targeting resources in relation to a particular water quality concern, focusing best management efforts, and maximizing benefits to water quality with minimal costs.

Inequity in ecosystem service delivery: socioeconomic gaps in the public-private conservation network

“…The distance over which benefits may be conveyed varies among services as well as naturally with topography (e.g., slope) and with the assistance of human-built infrastructure. One example is the extensive aqueduct system that carries drinking water from the CatskillDelaware and Croton drinking water supply watersheds to New York City (Mehaffey et al 2005). An ES framework coming out of South East Queensland, Australia provides an excellent overview of the directional biases associated with ES delivery (http://www.ecosystemservicesseq.com.au/ecosystem-services.html); however, there are no well-defined thresholds for evaluating the flow of benefits at a regional scale such as the bistate focus of this analysis.…”

Zoning and Analysis of Control Units for Water Pollution Control in the Yangtze River Basin, China

“…Figure 2 shows the three-level water resources zones in the Yangtze River Basin, including 12 second-level water resources zones and 45 third-level water resources zones. The zone is further divided into the fourth-level hydrological units (Figure 3-II), the fifth-level small hydrological units (Figure 3-III), and the sixth-level micro hydrology units (Figure 3-IV) based on the data of 30-meter resolution digital elevation model (DEM) using GIS hydrological analysis tools [29][30][31] with the boundary being the boundaries of the Chishui River Zone. Together with the three-level water resources zoning, the newly created three-level hydrological units form a multi-level hydrological zone for the whole basin, as shown in Figure 3-V.…”

Effects of land-use patterns on in-stream nitrogen in a highly-polluted river basin in Northeast China

“…Digital elevation data and stream networks were used to delineate the subwatersheds for each of the 30 sampling sites by using the point coordinates as stream outlets (Mehaffey et al, 2005). On the basis of land-use types in different subwatersheds, the Haicheng River basin was divided into six zones ( Fig.…”