scholarly journals River water quality changes in New Zealand over 26 years (1989–2014): Response to land use and land disturbance

2016 ◽  
Author(s):  
Jason P. Julian ◽  
Kirsten M. de Beurs ◽  
Braden Owsley ◽  
Robert J. Davies-Colley ◽  
Anne-Gaelle E. Ausseil
Keyword(s):  
Water Quality ◽  
Land Use ◽  
New Zealand ◽  
River Water ◽  
River Water Quality ◽  
Point Sources ◽  
Diffuse Pollution ◽  
Sediment Runoff ◽  
Nutrient Mobilization ◽  
Land Disturbance

Abstract. River water quality reflects land use in the catchment (mobilizing diffuse pollution) as well as point source discharges. In New Zealand (NZ) diffuse pollution vastly outweighs point sources which have largely cleaned up over many decades. Because NZ has good geospatial data on physiographic variables, land cover and agricultural statistics, and time series on water quality at the national scale over several decades, the country is a natural laboratory for investigating water quality response to land use/disturbance and associated diffuse pollution "pressures". We interpreted water quality state and trends for the 26 years from 1989 and 2014 in the National Rivers Water Quality Network (NRWQN), consisting of 77 sites on 35 mostly large river systems with an aggregate catchment amounting to half of NZ's land area. To characterize water quality pressures, we used multiple land use datasets spanning 1990–2012, plus recently-developed 8-day land-disturbance datasets using MODIS imagery. Current state and directions of change in visual clarity and nitrate-nitrite-nitrogen provide a particularly valuable summary of impact, respectively from mobilization of fine particulate matter and soluble nutrients. We show that the greatest impact on river water quality in NZ over the 1989–2014 period is high-producing pastures with their high nutrient inputs to support high densities of livestock. While land disturbance was not itself a strong predictor of water quality, it did help explain outliers of land use-water quality relationships, especially those with large areas of plantation forest. Plantation forestry was strongly associated with water quality impacts, particularly on visual clarity and particulate nutrients when land disturbed for harvesting generated sediment runoff and nutrient mobilization. In all, our study demonstrates how interdisciplinary combinations of expertise including geospatial analysis, land management, remote-sensing, and water quality can advance understanding of broad-scale and long-term impacts of land use change on river water quality.

scholarly journals River water quality changes in New Zealand over 26 years: response to land use intensity

2017 ◽  
Vol 21 (2) ◽  
pp. 1149-1171 ◽  
Author(s):  
Jason P. Julian ◽  
Kirsten M. de Beurs ◽  
Braden Owsley ◽  
Robert J. Davies-Colley ◽  
Anne-Gaelle E. Ausseil
Keyword(s):  
Water Quality ◽  
Land Use ◽  
New Zealand ◽  
River Water ◽  
River Water Quality ◽  
Land Use Intensity ◽  
Land Disturbance ◽  
Areal Coverage ◽  
Legacy Nutrients ◽  
Intensively Managed

Abstract. Relationships between land use and water quality are complex with interdependencies, feedbacks, and legacy effects. Most river water quality studies have assessed catchment land use as areal coverage, but here, we hypothesize and test whether land use intensity – the inputs (fertilizer, livestock) and activities (vegetation removal) of land use – is a better predictor of environmental impact. We use New Zealand (NZ) as a case study because it has had one of the highest rates of agricultural land intensification globally over recent decades. We interpreted water quality state and trends for the 26 years from 1989 to 2014 in the National Rivers Water Quality Network (NRWQN) – consisting of 77 sites on 35 mostly large river systems. To characterize land use intensity, we analyzed spatial and temporal changes in livestock density and land disturbance (i.e., bare soil resulting from vegetation loss by either grazing or forest harvesting) at the catchment scale, as well as fertilizer inputs at the national scale. Using simple multivariate statistical analyses across the 77 catchments, we found that median visual water clarity was best predicted inversely by areal coverage of intensively managed pastures. The primary predictor for all four nutrient variables (TN, NOx, TP, DRP), however, was cattle density, with plantation forest coverage as the secondary predictor variable. While land disturbance was not itself a strong predictor of water quality, it did help explain outliers of land use–water quality relationships. From 1990 to 2014, visual clarity significantly improved in 35 out of 77 (34∕77) catchments, which we attribute mainly to increased dairy cattle exclusion from rivers (despite dairy expansion) and the considerable decrease in sheep numbers across the NZ landscape, from 58 million sheep in 1990 to 31 million in 2012. Nutrient concentrations increased in many of NZ's rivers with dissolved oxidized nitrogen significantly increasing in 27∕77 catchments, which we largely attribute to increased cattle density and legacy nutrients that have built up on intensively managed grasslands and plantation forests since the 1950s and are slowly leaking to the rivers. Despite recent improvements in water quality for some NZ rivers, these legacy nutrients and continued agricultural intensification are expected to pose broad-scale environmental problems for decades to come.

Suggestions for a Modified Approach Towards Implementation and Assessment of Ganga Action Plan and Other Similar River Action Plans in India

2003 ◽  
Vol 38 (4) ◽  
pp. 607-626 ◽  
Author(s):  
Vinod Tare ◽  
Purnendu Bose ◽  
Santosh K. Gupta
Keyword(s):  
Water Quality ◽  
River Water ◽  
Public Perception ◽  
Nutrient Loading ◽  
Action Plan ◽  
Public Support ◽  
Uttar Pradesh ◽  
River Water Quality ◽  
Point Sources ◽  
Action Plans

Abstract In India, the implementation of river-cleaning operations through River Action Plans (RAPs) conventionally focuses on a reduction in concentrated or point sources of organic loading to the river, and is assessed by monitoring the consequent improvement in river water quality. However, in the case of Indian rivers or river stretches having substantial background pollution due to distributed or non-point loading of organic matter and nutrients, elimination of point sources of pollution may not substantially impact or improve river water quality. It is suggested that implementation of River Action Plans in India under such circumstances must be conducted using a multi-tier approach. The initial emphasis in such cases should be on the selection of priority stretches of the river, where pollution control will have maximum beneficial impact on the citizens, and interception and diversion of all concentrated or point loads of pollution from these stretches. In addition, measures to minimize non-point pollution and visible pollution to the river and initiation of riverfront restoration and development projects are necessary in these priority stretches. Such measures would result in aesthetic improvements, increase the beneficial uses of the river and its surroundings, and generate favorable public perception towards RAPs, though they may not be sufficient to enhance the river water quality to the desired levels. However, as a result of the above actions, public support for funding more expensive and longer-term river cleaning schemes, resulting in comprehensive reduction in organic and nutrient loading to the river from point and non-point sources all along its length, may be generated. The need for this alternative methodology for implementation and assessment of RAPs in India has been illustrated by taking the example of the Ganga Action Plan (GAP) and assessment of its implementation near the city of Kanpur in the state of Uttar Pradesh, India, as a test case.

Impact of land use and urbanization on river water quality and ecology in a dam dominated basin

2020 ◽  
Vol 584 ◽  
pp. 124655 ◽  
Author(s):  
Zengliang Luo ◽  
Quanxi Shao ◽  
Qiting Zuo ◽  
Yaokui Cui
Keyword(s):  
Water Quality ◽  
Land Use ◽  
River Water ◽  
River Water Quality

scholarly journals Assessment of river water quality during snowmelt and base flow periods in two catchment areas with different land use

2007 ◽  
Vol 137 (1-3) ◽  
pp. 251-260 ◽  
Author(s):  
Krishna Prasad Woli ◽  
Atsushi Hayakawa ◽  
Kanta Kuramochi ◽  
Ryusuke Hatano
Keyword(s):  
Water Quality ◽  
Land Use ◽  
River Water ◽  
River Water Quality ◽  
Base Flow ◽  
Catchment Areas
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