Preliminary assessment of the ability of detainment bunds to attenuate sediment and phosphorus transported by surface runoff in the Lake Rotorua catchment

2020 ◽  
Vol 60 (1) ◽  
pp. 154 ◽  
Author(s):  
Brian Levine ◽  
Lucy Burkitt ◽  
Dave Horne ◽  
Leo Condron ◽  
Chris Tanner ◽  
...  

Water-quality impairment due to excess nutrients entering Lake Rotorua has been recognised since the 1960s. So as to improve water-quality, the 2012 Lake Rotorua Nutrient Management Plan has set a target to reduce phosphorus (P) loads delivered to the lake by 10 t/year from a baseline of ~40 t P/year. Dissolved P and sediment-bound P loss from agriculture have been identified as significant sources of P entering the lake. Storm periods present significant opportunities to mitigate these losses. Detainment bunds (DBs) are a mitigation strategy that could potentially decrease P losses in storm events. A detainment bund is a low earthen dam constructed on productive pasture, which is capable of temporarily ponding large quantities of overland flow delivered by storm-generated ephemeral streams. Prior research on DBs and sedimentation basins serves as a proof of concept for the technology; however, there is no quantitative data available on the capacity of DBs to attenuate contaminants under New Zealand conditions. Quantification of DB performance is essential to the potential implementation of the technology at regional or national scales, and to the modelling of treatment efficacy in nutrient-management software such as OVERSEER®. The present study reports on preliminary data from a DB receiving surface runoff from 19.7 ha within the Lake Rotorua catchment during three contrasting storm events. The results indicated that retaining water in DBs resulted in discharges with decreased volumes of water and decreased concentrations of suspended sediments, dissolved reactive P and total P. Load attenuation related to event size and resulted in decreased loads of sediment (14–91%), dissolved reactive P (19–69%) and total P loads (18–67%) discharged downstream. These preliminary results indicated the potential of this mitigation strategy to decrease loads of sediment and P delivered to Lake Rotorua by surface runoff from pastoral agriculture.

2019 ◽  
Vol 50 (4) ◽  
pp. 1047-1061 ◽  
Author(s):  
Palki Arora ◽  
Jasmeet Lamba ◽  
Puneet Srivastava ◽  
Latif Kalin

Abstract The linkages among the best management practices implemented at the field level and downstream water quality improvement at the watershed level are complex, because the processes that link management practices and watershed-level water quality span a range of scales. However, it is important to understand the effect of nutrient management strategies on watershed-level water quality because most of the water quality evaluation occurs at the watershed scale. The overall goal of this study was to quantify the effect of broiler litter application method (surface vs. subsurface application) on phosphorus (P) and nitrogen (N) losses in surface runoff using the Soil and Water Assessment Tool (SWAT) model. The research was conducted in the Big Creek watershed (8,024 ha) located in Mobile County, Alabama, USA. At the hydrological response unit level, the subsurface application of broiler litter to pastures reduced average annual (1991–2015) total P and N losses in surface runoff by 72% and 33%, respectively, compared to surface application of broiler litter. At the watershed outlet, subsurface application of broiler litter to pastures (covered 43% of the watershed area after the land use change scenario) reduced average annual (1991–2015) total P and N losses by 39% and 20%, respectively.


2010 ◽  
Vol 107 ◽  
pp. 21-26
Author(s):  
Maria Regina de Aquino-Silva ◽  
P.R.C. Leone ◽  
Eduardo Jorge de Brito Bastos

The sand exploration results in ponds, which are formed by groundwater. The supply of nutrients (especially nitrogen and phosphorus) in these environments leads to greater growth of aquatic plants – eutrophication, which can cause interference to the different uses of these ponds. This study aimed to identify the main causes of eutrophication of these environments and propose a management plan to ensure its future use and maintenance of water quality. The experiment was carried out between the cities of São José dos Campos and Jacarei (SP-Brazil) (S 23° 12" 54' e W 45° 57" 47'). The topographic map indicates the flow of water during the rainy season and the places with the greatest possibility of drag of nutrients through laminar erosion. The analysis of water showed the variation in levels of nitrogen (increase) and phosphorus (decrease). This variation occurred in the area of higher elevation to lower elevation. The climatological water balance indicated overland flow and water holding in the soil concentrated in the months of January, February, March and April. The results indicate that the water stored in soil, and environment's topography may influence on the process of eutrophication of the sand mining pool


Soil Research ◽  
2012 ◽  
Vol 50 (6) ◽  
pp. 515 ◽  
Author(s):  
Peter R. Stork ◽  
David J. Lyons

Phosphorus (P) in overland flow from horticulture farms in coastal Queensland, Australia, could eutrophy coastal freshwater and marine habitats environments nearby. The potential for such eutrophication was investigated in a coastal macadamia plantation under commercial production. During the 13-month study, P losses in overland flow were quantified in a 0.24-ha farm catchment with a 3.1% gradient, during five consecutive storm events. These events were within expected short- and long-term episodic rainfall frequencies and intensities. Runoff occurred when such storms generated between 20–40 mm/h of rainfall for >9 min. Calculated annual losses of total P were 0.32 kg/ha.year, comprising dissolved inorganic P (DIP, 0.28 kg/ha.year), particulate P (0.03 kg/ha.year), and dissolved organic P (0.01 kg/ha.year). DIP represented 88% of all losses and this was attributed to excessive fertilisation and untimely applications. Losses of total P were generally higher than those reported in comparable studies. Concentrations of DIP in runoff were 20–200-fold higher than those found in other coastal catchments in Queensland. High concentrations of DIP were present in the topsoil of the non-fertilised, inter-row areas of the farm catchment and this was attributed to transfer and deposition of DIP from adjacent fertilised tree beds during storm flow. Therefore, it can be expected that farm runoff will be enriched with DIP from these areas for an indeterminate period despite any future remediation to fertiliser management. The weighted average of DIP in farm runoff was 2.01 mg/L, whereas it was 0.005 mg/L in a catchment stream bordering the farm, showing a steep concentration gradient between the two ecosystem compartments. Together with nitrogen (N) losses in runoff, reported previously, an N : P molar ratio of 2 : 1 was contained in the farm runoff. This was well below the growth-limiting threshold for aquatic organisms, as determined by the Redfield ratio of 16 : 1 (N : P). The entry of nutrient-enriched farm runoff, as detailed in this study, into the catchment stream and the proximity of such waterways (8 km) to the coastline may also have implications for the near-shore (oligotrophic) marine environment during periods of storm flow. Altogether, this work revealed the high risk of eutrophication from farming landscapes such as the one under study.


1994 ◽  
Vol 29 (2-3) ◽  
pp. 221-232
Author(s):  
M.J. McCormick

Abstract Four one-dimensional models which have been used to characterize surface mixed layer (ML) processes and the thermal structure are described. Although most any model can be calibrated to mimic surface water temperatures, it does not imply that the corresponding mixing processes are well described. Eddy diffusion or "K" models can exhibit this problem. If a ML model is to be useful for water quality applications, then it must be able to resolve storm events and, therefore, be able to simulate the ML depth, h, and its time rate of change, dh/dt. A general water quality model is derived from mass conservation principles to demonstrate how ML models can be used in a physically meaningful way to address water quality issues.


1995 ◽  
Vol 32 (2) ◽  
pp. 281-288
Author(s):  
Susan Taljaard ◽  
Willem A. M. Botes

In South Africa the ultimate goal in water quality management is to keep the water resources suitable for all “beneficial uses”. Beneficial uses provides a basis for the derivation of water quality guidelines, which, for South Africa, are defined in Water quality guidelines for the South African coastal zone (DWAF, 1991). The CSIR has developed a practical approach to marine water quality management, taking into account international trends and local experience, which can be applied to any coastal development with potential influence on water quality. The management plan is divided into three logical components, i.e. • site-specific statutory requirements and environmental objectives; • system design with specific reference to influences on water quality; and • monitoring programmes. Within this management approach water quality issues are addressed in a holistic manner, through focused procedures and clear identification of information requirements. This paper describes the procedures and information requirements within each component of the water quality management plan, with specific reference to marine disposal systems. Ideally, the management plan should be implemented from the feasibility and conceptual design phase of a development and the timing of the different procedures within the development process are therefore also highlighted. However, the logical lay-out of procedures allows for easy initiation (even to existing disposal system) at any stage of development.


1992 ◽  
Vol 26 (7-8) ◽  
pp. 1851-1856 ◽  
Author(s):  
J. L. Lai ◽  
K. S. L. Lo

A mixing-based model for describing solute transfer to overland flow was developed. This model included a time-dependent mixing depth of the top layer and a complete-mixed surface runoff zone. In a series of laboratory experiments, runoff was passed at various velocities and depths over a medium bed. The media were saturated with uniform concentration of potassium chloride solution. Runoff water was sampled at the beginning and end of the flume and the potassium chloride concentration analyzed. Using this model, dimensionless ultimate mixing depth and dimensionless change rate of mixing depth from experimental data were investigated and implemented. The results showed that the Reynolds number and relative roughness are two important factors.


1998 ◽  
Vol 37 (1) ◽  
pp. 251-257 ◽  
Author(s):  
Torben Larsen ◽  
Kirsten Broch ◽  
Margit Riis Andersen

The paper describes the results of measurements from a 2 year period on a 95 hectare urban catchment in Aalborg, Denmark. The results of the rain/discharge measurements include 160 storm events corresponding to an accumulated rain depth of totally 753 mm. The water quality measurements include 15 events with time series of concentration of SS, COD, BOD, total nitrogen and total phosphorus. The quality parameters showed significant first flush effects. The paper discusses whether either the event average concentration or the accumulated event mass is the most appropriate way to characterize the quality of the outflow.


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