Identifying Surface Runoff Pathways for Cost-Effective Mitigation of Pollutant Inputs to Drinking Water Reservoir

Jolanta Dąbrowska,Iwona Lejcuś,Paweł Dąbek

doi:10.3390/w10101300

Abstract

Surface runoff (overland flow) is the main element of the water cycle and is also crucial in the delivery of phosphorus and nitrogen from catchments to water bodies. Watercourses and reservoirs in agricultural catchments are particularly vulnerable to the delivery of biogenic compounds via surface runoff. Forested riparian buffers are considered effective in reducing nutrients and sediment loads in runoff from agricultural areas. Regrettably, the concentration of surface runoff may significantly limit the buffering capacity of vegetation strips, as channelised overland flow tends to avoid buffers without making optimal use of their ability to retain nutrients and sediment. The aim of the undertaken research was to delineate surface runoff pathways from surrounding areas to a drinking water reservoir as well as to identify potential concentration spots of overland flow. The research was conducted for the Dobromierz drinking water reservoir (GPS N: 50°54′27″, E: 16°14′37″). The reservoir is situated in a submountain catchment, where rainfall is an important factor taking part in driving diffuse P and N loads from land to water. Presented GIS-based method using high resolution Digital Terrain Model obtained from Light Detection and Ranging (LiDAR) allowed to determine areas with a tendency for high accumulation (concentration) of overland flow in the direct catchment of the reservoir. As main surface runoff areas, three sites each exceeding 100 ha were designated. The analysis of spatial data also allowed to establish the risk of agricultural diffuse pollution transfer via channelised overland flow to the reservoir from individual accumulation areas. It was found that in the forested part of the catchment (serving as a riparian buffer) there is no visible tendency for concentration of surface runoff, but simultaneously the vegetation strip does not prevent the transfer of runoff waters from agricultural areas through the privileged pathways of concentrated flow.

Highlights

Eutrophication is one of the most important worldwide environmental challenges and the major problem for sustainable water management of water bodies
It was found that in the forested part of the catchment there is no visible tendency for concentration of surface runoff, but simultaneously the vegetation strip does not prevent the transfer of runoff waters from agricultural areas through the privileged pathways of concentrated flow
The potential for high concentration of overland flow was indicated for three main surface runoff areas exceeding 100 ha

Summary

Introduction

Eutrophication is one of the most important worldwide environmental challenges and the major problem for sustainable water management of water bodies. Human activities have accelerated the rate and extent of eutrophication through excessive nutrient (mostly phosphorus and nitrogen) loading to aquatic ecosystems from both point and nonpoint sources of pollution. In numerous regions of the world, the problem of point sources of pollution, connected mainly with insufficient wastewater. Hydrological flow paths have been recognised as a crucial element in the investigation of phosphorus (P) and nitrogen (N) delivery from catchment to surface water. Overland flow is essential in the relocation of agricultural pollutants [6,7], being the main transport route for phosphorus compounds—dissolved and particulate forms and an important route for nitrogen compounds—organic forms associated with eroded soil and a soluble mineral form [8,9]. Pollutant transport via surface runoff is especially intensified in catchments which are hydrologically sensitive to rainfall (vulnerable to contamination following precipitation events)

Methods

Results

Conclusion