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Publication Open Access Using rainwater tanks as stormwater control measures to improve runoff and water quality management in urban areas : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Water Resource Management at Lincoln University(Lincoln University, 2020) Odeh, MohamadUrbanisation and associated human activities impact rivers and streams that flow through urban areas. Impacts include receiving large volumes of stormwater runoff loaded with high concentrations of contaminants during rainfall events. Different decentralised stormwater control measures such as raingardens and rainwater harvesting tanks have been used to mitigate stormwater runoff in urban areas, and different natural materials such as mussel shell waste have been incorporated in these measures to remove contaminants in runoff near pollution sources. Rainwater tanks have been recently recognised as stormwater control measures based on the tank’s ability to detain roof runoff during rainfall events. Despite the increased attention on using rainwater tanks to mitigate stormwater runoff in urban areas, there is still a lack of knowledge regarding their effectiveness to mitigate stormwater runoff at different scales of urban areas such as industrial and residential lands. Furthermore, the use of filtration units in the rainwater tanks to improve the mitigation performance and to remove common contaminants in roof runoff such as zinc have not been investigated yet. The mussel shell wastes have been used to remove dissolved zinc from stormwater runoff in stormwater control measures. However, the removal efficiency of zinc during different filtration conditions such as varied flow rates and short contact times with water have not been fully investigated yet. Therefore, this thesis investigated the use of mussel shell waste as filtration media in rainwater tanks to remove zinc from roof runoff, and evaluated the use of rainwater tanks to mitigate stormwater runoff at residential and industrial scales in Christchurch, New Zealand. The effectiveness of mussel shell to remove zinc was investigated for untreated mussel shell (UTMS), and heat-treated mussel shell (TMS). Two types of filtration units were designed to investigate the use of UTMS and TMS as filtration media in the rainwater tank. The first filtration units included 1.0 m depths of the filtration media connected to a gravity-driven outlet, and the second filtration units included 0.8 m depths of the filtration media connected to a siphonic-driven outlet. An actual roof runoff was collected from galvanised roofing, and the removal performance of zinc was estimated during controlled saturated flow rates of 1, 3, 5, 10 L/min. The collected roof runoff showed high concentrations of dissolved zinc with an average zinc concentration of 3347.2 μg/L, which is ca. 200 times higher than the recommended concentration of zinc in urban streams (i.e. 15 μg/L) to protect 90% of the freshwater organisms according to the ANZECC’s guidelines (ANZECC, 2000). Both the TMS and UTMS demonstrated high removal efficiencies of dissolved zinc. The heat treatment of the mussel shell generally improved the removal performance of dissolved zinc. The TMS media showed significantly higher (p ≤0.05) removal performance of zinc compared to the UTMS media for the tested flow rates during 0.8 m depths of filtration media, while the TMS showed higher average removal efficiencies but with there was no significant difference (p > 0.05) for the tested flow rates during the 1.0 depths. For all flow rates, the overall average removal efficiencies of the TMS were estimated at 94% and 82% for 1.0 m and 0.8 m depths of filtration media respectively, while the overall average removal efficiencies of the UTMS were estimated at 92% and 72% for 1.0 m and 0.8 m depths of filtration media respectively. The removal performance of zinc decreased as water flow rates through the TMS and UTMS increased. The EPA's Storm Water Management Model (SWMM) was used to evaluate the mitigation performance of rainwater tanks for two urban blocks that represented the residential and industrial land use in Christchurch, New Zealand. Three management scenarios were simulated using 5-min time steps throughout a 12-year period starting from 4 November 2007 until 4 November 2019. The first management scenario represented the Business As Usual ( BAU) conditions, and used as the reference of actual stormwater peaks and total volumes of outflow in the selected blocks. The second management scenario represents using Rainwater Harvesting for Toilet Flushing (RWH-TF) uses which simulated the use of collected rainwater to supply water for toilet flushing uses in the existing buildings of the selected blocks. The third management scenario represents using Rainwater Harvesting for Stormwater Treatment (RWH-ST) uses which simulated the use of rainwater tanks and filtration units as stormwater detention units to collect, and slowly discharge treated roof runoff into the stormwater network. The simulation results showed effective mitigation performance in both the residential and industrial blocks. The average reductions in peak runoff during the RWH-ST scenarios were estimated at 52.9% and 45% in the residential and industrial blocks respectively, while the average reductions in runoff volumes were estimated for 37.3% and 19.5%. The RWH-TF scenarios showed lower peak reductions with averages estimated at 36.3% and 23.9% in the residential and industrial blocks respectively, while the average volume reductions estimated at 42.9% and 27.5% in the residential and industrial blocks respectively. During RWH-ST scenario, the integrated rainwater tanks with filtration units showed effective treatment performance throughout the simulation period with more than 99% and 58% treatment ratio of roof runoff in the simulated residential and industrial blocks respectively. The results of this thesis exposed potential benefits for using integrated rainwater harvesting tanks (i.e. with filtration units) as stormwater control solutions to improve runoff and water quality management in urban areas. In particular, the use of mussel shell waste as filtration media in rainwater tanks provided cost-effective solutions to remove metals from runoff in order to protect the ecological conditions in urban waterways, and the use of rainwater tanks reduced stormwater runoff volumes and peak flows during rainfall events at both residential and industrial scales.Publication Open Access Assessing impacts of climate change on water resources and agriculture: A case study of Tonle Sap basin, Cambodia : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Water Resource Management at Lincoln University(Lincoln University, 2020) Ly, SoknaCambodia’s Tonle Sap Lake is the largest permanent freshwater body not just in Cambodia, but in Southeast Asia, and is also one of the world’s richest lacustrine-wetland ecosystems. Agriculture and fisheries provide the primary livelihoods of people living in the area. Despite a high abundance of natural resources, the area around Tonle Sap Lake is known to be one of the poorest areas in Cambodia, where most people derive their livelihoods directly from the resources provided by the lake. This study aims to assess the impacts caused by climate change on water resources and agricultural production in the basin by looking into future changes of streamflow of the tributary rivers, flood pulse and the paddy rice areas supported by the Mekong River’s flood pulse. For this study, six climate change scenarios were employed to assess future change in rainfall and river flow. They are the result of the combinations between three global circulation models (GFDL-CM3, GISS-E2-R-CC and IPSL-CM5A-MR) and two representative concentration pathways (RCP4.5 and RCP8.5). HEC-HMS was used for simulating rainfall and runoff for 11 sub-basins that feed the Tonle Sap Lake. HEC-RAS was used for computing inundation areas around the lake. Both models were calibrated and validated using data for the year 2000–2005 and 2006–2007, respectively. The results from HEC-RAS were exported in a format that enabled further analysis in GIS to examine changes to paddy rice areas at both the basin- and sub-basin scales. Both HEC-HMS and HEC-RAS model performances were evaluated using statistical indices NSE and R2. The indices indicated satisfactory performance for both simulation models with NSE > 0.40 and R2 > 0.60 for HEC-HMS and NSE > 0.60 and R2 ≥ 0.90 for HEC-RAS. The main findings in the study were the reduction of annual streamflow that is projected to occur in almost every sub-basin under all climate change scenarios up to the year 2030. The Dauntri sub-basin is projected to experience the highest streamflow decrease, up to 62.53%, while streamflow in the Sen and Boribor sub-basins showed a slight increase. The results from HEC-RAS suggest a decrease of flood pulse extent under all climate change scenarios. The magnitudes of decrease are almost the same for each scenario with an average decrease of around 10%. The Sen sub-basin showed the greatest reduction of flooded areas (13.82%) while Sangker was projected to decrease the least (2.00%). Though the Sen and Boribor catchments show an increase in streamflow, the increase is offset by the reduced flows in the remaining catchments, thus contributing less flow to the lake overall, leading to its reduced area. The results also suggest a decrease in paddy rice areas supported by the flood pulse. Stuang is the sub-basin with the highest reduction of paddy rice areas of up to 28.36%, while Sangker remains the sub-basin with the least reduction (2.67%). Some noteworthy implications arise from the main findings. The decrease of flows in the tributary rivers suggests an increase in drought risk and consequences for household water supply and surface irrigation that divert or extract water from those rivers. The change of the extent of flood pulse suggests that there will be lower nutrients and sediment loads and this would substantially impact the ecosystems in the lake and other connected parts. The reduction of paddy rice areas underscores the potential implications for social and economic development such as food insecurity, unemployment and economic impacts.Publication Restricted The effects of high lake levels due to climate change on lakeside communities and adjacent land use: Case study: Lake Ellesmere/Te Waihora : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Water Resource Management at Lincoln University(Lincoln University, 2019) Zarour, DaliaThis research aims to assess the effects of sea-level rise on Lake Ellesmere/Te Waihora’s current opening regime and consequently on adjacent land and it’s lakeside communities. The research also aims to assess Lake Ellesmere/Te Waihora’s lakeside communities’ level of preparedness to adapt to these anticipated changes. Unlike other natural hazards that occur abruptly, sea-level rise is incremental and foreseeable, and its effects on coastal areas and communities are expected to occur gradually. Thus, it is crucial to start planning now for future sea-level rise to reduce its adverse impacts on coastal areas and communities. Intermittently closed and open lakes and lagoons (ICOLLs) such as Lake Ellesmere/Te Waihora are vulnerable to the effects of sea-level rise due to their setting within the coastal landscape. The water level of many ICOLLs around the world, including Lake Ellesmere/Te Waihora, are managed by artificially creating a temporary opening through the barrier separating the ICOLL from the sea and inducing premature breakout to protect adjacent land and communities from inundation. The artificial opening is induced when a predefined opening trigger value is reached. The success of the artificial opening is dependent on local sea conditions. As sea levels continue to rise, the continuation of flood management practice in the form of artificial openings for ICOLLs will become challenging due to a decrease in hydraulic gradient between the ICOLL and the sea. Eventually, in order to be able to open Lake Ellesmere/Te Waihora to flow into the sea, the current predefined trigger value will have to increase in height relative to local sea level rise. In the short-term future, this will result in an increase in the risk of temporary inundation of adjacent land. In the long-term future, the increase of the ICOLL artificial opening trigger levels will result in permanent loss of adjacent land and the displacement of communities. A quantitative risk assessment was carried out to determine the effects of sea-level rise on Lake Ellesmere/Te Waihora’s artificial opening trigger levels in the short-term (10 to 30 years) and longer-term (50 to 100 years). This quantitative risk assessment was also able to determine the probable risk of permanent inundation of adjacent land. Geographic Information Systems were used to create contour maps showing the increase in Lake Ellesmere/Te Waihora’s current summer and winter artificial opening trigger levels in response to future sea-level rise. These maps are used to determine who will be affected by increasing amounts of sea level rise. Additionally, a qualitative risk assessment was undertaken to assess the level of preparedness of Lake Ellesmere/Te Waihora’s communities that have been identified to be at risk of inundation as a result of the anticipated increase in the lake’s water levels.Publication Open Access Upscaling of point-scale groundwater recharge measurements using machine learning: A case study in New Zealand and Colombia(Lincoln University, 2019) Rios Rivera, Manuel AlejandroEstimating groundwater (GW) recharge rates is essential for water resources decision-making, in particular for dynamic regional-scale allocation. Typically, recharge has been estimated either based on models that require observed historic climatic and soil data for calibration or through measurements at a lysimeter monitoring site. Lysimeters are known as the most direct method of measuring drainage, yet utilization for decision making in regional water management is limited as merely point-scale measures of recharge are provided. In the past, machine learning techniques such as artificial neural networks (ANNs) have been found robust for modelling nonlinear hydrologic processes in relation to groundwater management. For this study, an ANN was selected in order to evaluate whether decision making in groundwater allocation can be improved by upscaling lysimeter-measured recharge. Model uncertainty for the ANN scheme was estimated employing a “Dropout” Monte Carlo (MC) technique. The ANN was trained and assessed in terms of its predictive performance to match lysimeter-measured recharge. The ANN was trained on daily time scale, employing recharge data recorded at three lysimeter stations in the Canterbury plains of New Zealand i.e. Dorie, Dunsandel and Methven sites. The best model in terms of accuracy and parsimony, provided R² values ranging from 0.65 up to 0.86 and a mean absolute error ranging from 0.41 to 0.99 when tested at the three lysimeter locations, with a model uncertainty of 6%. The model was implemented in a geographic information system (GIS) environment, in order to predict the spatial variability of land surface recharge, but also to calculate GW allocation for three of the groundwater allocation zones of the Canterbury Region (i.e. Rakaia-Selwyn, Ashburton and Chertsey). GW available for allocation was estimated to be approximately 650 * 106 m³ year⁻¹ or the Rakaia-Selwyn allocation zone; whereas allocation limits of 284.41 * 106 m³ year⁻¹ and 332.45 * 106 m³ year⁻¹ were estimated for Ashburton and Chertsey respectively. The suitability of applying an ANN to estimate LSR in a comparably data scarce region in Colombia was also tested. The results support how the inclusion of lysimeter data into the analysis, improves our confidence regarding the estimation of groundwater recharge. The methodology developed in this study couples a supervised machine learning technique i.e. ANNs with a visualisation tool in a GIS to predict land surface recharge employing rainfall, potential evapotranspiration and dominant soil texture data as inputs. The tool developed here can be utilised to provide support to water managers in order to identify sustainable dynamic regional groundwater allocation strategies.Publication Open Access Investigation of nutrient management trade-offs using the Land Utilisation Capability Indicator (LUCI). A Canterbury, New Zealand, case study(Lincoln University, 2019) Gowera, Grace TariroAlthough agricultural productivity aims to meet global food demand, its expansion and intensification has led to an increase in nutrient load in waterways affecting water quality. This places farmers under pressure in controlling nutrient loss and conserving ecosystem services. The Land Utilisation Capability Indicator (LUCI) model can assist farmers in meeting freshwater policy requirements and identifying where changes on current land management can be done. LUCI is an ecosystem service modelling tool that illustrates the impacts of various ecosystem services. The model was applied in the Selwyn catchment to identify trade-offs between agricultural productivity and water quality. Trade-off results highlighted the possibility of improving water quality at the expense of agricultural productivity. However, to minimise loss of agricultural land or productivity, LUCI identified specific positions within the catchment which require nutrient mitigation. The study also modified the LUCI model. Without any alterations, LUCI uses soil type to determine nutrient loads in a catchment. Modifications done enabled land use to determine nutrient loads. The modifications included adding the Selwyn catchment farm data into the Land Cover Database (LCDB4), assigning export co-efficient (EC) values to different farm types in the study area. LUCI uses the export coefficient approach to calculate nutrient load of an area. Results from the modification process identified dairy farmers as major contributors of nutrient load.Publication Restricted How has contamination to water supply altered Havelock North business owners’ perspectives on water? : A thesis submitted in partial fulfilment of the requirements for the degree of Master at Lincoln University and Waterways Centre for Freshwater Management(Lincoln University, 2018) Teen, Rachel MarySafe drinking water is essential to public health. In August 2016 an outbreak of gastroenteritis in Havelock North, New Zealand, shook the public’s trust in the water supply service. Over 5,500 of the town’s 14,000 residents were estimated to have fallen ill with campylobacteriosis, and 45 people were hospitalised. There were three attributable deaths and an unknown number still suffer on-going health issues. Consequently business owners were detrimentally affected – financially, operationally and emotionally. Their perceptions of water were immediately affected, particularly with the application of chlorine to the water supply, and their trust in their local government bodies diminished. Transformative Learning Theory was the lens used to ascertain if the contamination event transformed Havelock North business owners’ perspectives on water. Perspective change is most likely to occur when people experience a series of sensory perceptionary encounters, also critically reflect on the complete context of those physical and mental perceptions, and additionally, critically self-reflect on how they can transform the context or situation and then take action. All business owners underwent changes in perception concerning their water supply and all critically reflected on the context of the contamination event. However, none were deemed to have undergone a transformation in their perspectives on water because they did not engage in any critical self-reflection. The various causes of the contamination were all external to Havelock North business owners, they perceived there was no need for them to critically self-reflect on themselves nor their business strategies. Their perceptions in regard to the importance of water did change because the event made many of them realise how integral water was to trading and remaining operational. The disruption triggered them to think about the connectivity of water to natural ecosystems, including humanity. Business owners unquestioningly accepted the unwritten hydrosocial contract with the local councils, and none had experienced a transformative perspective change whereby they sought to renegotiate this contract.Publication Restricted Development of an integrative water quality monitoring programme for Te Waihora/Lake Ellesmere(Lincoln University, 2018) McMillan, ValerieFresh water lakes are highly valued in today’s world. The use and management of this freshwater resource is critical to all four well-beings (social, economic, environmental, and cultural) worldwide and specifically (for this thesis), in Canterbury, New Zealand. Lake Ellesmere/Te Waihora is a coastal ICOLL (Intermittently Closed and Open Lake or Lagoon) where the effects of the local climate patterns, the use and management of the large catchment associated with this lowland lake, its numerous stakeholders and changing legislation, have created a situation where robust relevant data is essential to ensure best and most cost-effective management of this resource. New Zealand legislation acknowledges the importance of this ICOLL within the whole system of New Zealand lakes, and views it as an indicator of New Zealand ICOLL behaviour. Water quality is an important facet of freshwater management and is one aspect of an overarching monitoring strategy for Te Waihora developed in 2015. Water quality monitoring in the lake is carried out by the regulatory body as well as many other stakeholders. This has led to an abundance of data addressing very specific objectives but also a number of gaps in the data required to assess the overall state of Te Waihora itself. The purpose of this research is to design a water quality monitoring programme integrating and augmenting existing programmes which will cost-effectively add to the information required for stakeholders and support current and future management. This research initially compiled information pertaining to lake character, the effects of land use within the large catchment and the local climatic conditions relevant to the lake, as well as existing monitoring programmes. An ‘ideal’ water quality monitoring programme with the main objective being “to assess the state and trends of water quality in Te Waihora and its immediate catchment” was then designed using specific predetermined criteria to select tributaries, monitoring sites, parameters and monitoring frequency. Current legislation and the importance of the local conditions for targeted monitoring to be achieved were incorporated and further information needs identified. The proposed monitoring programme requires monthly monitoring of six lake and eight tributary sites. The NPS-FM 2014 (amended 2017) and CLWRP water quality parameters, as well as parameters specific to Te Waihora are taken account of. These include monthly lake attributes (parameters) of lake level, pH, temperature, electrical conductivity, DO, turbidity, TSS, VSS, Secchi Disc, NO2-N, NO3-N, NH4-N, TN, DRP, TP, chl a and E. Coli and monthly tributary attributes (parameters) of discharge, pH, temperature, conductivity, DO, clarity, turbidity, TSS, NO2-N, NO3-N, NH4-N, TN, DRP, TP and E. Coli, with yearly monitoring for Cu, Pb, Zn, Cd, selected emerging contaminants and polyaromatic hydrocarbons (PAH). Additional monitoring is proposed for further specific parameters (e.g., flood and flow loads) at predetermined events (e.g., when tributary flow reaches a predetermined level). Tributary flow, lake level, climatic conditions and ICOLL status (open or closed) should also be recorded. This designed water quality monitoring programme has been compared with existing stakeholder monitoring programmes, to identify gaps and omissions and recommend methods for these to be addressed. Additional recommendations for methods to achieve the overarching integrative water quality monitoring objectives for foreseeable future requirements for management and modelling are also made. The ‘robustness’ and quality control of all aspects of the monitoring (practical and financial) is acknowledged as essential for longevity. Additional research into key areas, such as the sediment load related to flooding events, the combination of more extreme intermittent climatic conditions with increased intensification of catchment use, the effect of the Central Plains Water Ltd (CPWL) irrigation scheme and the effect of openings and closings on Te Waihora, are recommended to aid management decisions, aimed at not only sustaining the environment of the lake, but regenerating and improving it.Publication Open Access The removal of dissolved zinc and copper from roof-runoff: A downpipe treatment system(Lincoln University, 2018) Gregoire, NekeliaAnthropogenic activities related to urbanization and industrialization contribute high concentrations of heavy metals from urban stormwater runoff to waterways. In New Zealand, zinc (Zn) and copper (Cu) have been identified as the predominant heavy metals of concern because they have been observed to consistently exceed the Australian and New Zealand Environment and Conservation Council’s (ANZECC’s) guideline values for the protection of freshwater organisms in urban waterways. These heavy metals originate from a variety of sources, however, galvanized and copper roofs have been observed to contribute the highest per area Zn and Cu loads respectively. More so, >80% of the Zn and Cu released from these roofs are present in the dissolved reactive form making them more bioavailable and thus, potentially more toxic to aquatic organisms. Current stormwater management strategies have mostly focused on physical removal of particulate and particulate-bound contaminants while the dissolved contaminants are often left untreated. Also, it is difficult to retrofit conventional stormwater treatment devices such as retention ponds and raingardens in established urban areas due to limited space and the presence of underground services such as electricity, water and gas. Given that there are many existing Zn-and-Cu-based roofs in New Zealand whose runoff is discharged directly into the stormwater drainage system and/or waterways, there is a clear need to develop new at-source treatment devices that can remove these dissolved metals from roof-runoff. Sand have been the main treatment material used in stormwater filter systems, however, its removal efficiency for heavy metals have been observed to be low. As a result, this research explored the use of limestone, zeolite and mussel shells as treatment materials for the removal of dissolved Zn and Cu because of their high neutralization, adsorption and cation exchange capacity. The composition of calcium carbonate (CaCO3) in the structure of limestone and mussel shells, and the presence of alkali and alkaline earth elements sodium (Na+), potassium (K+), calcium (Ca2+) and magnesium (Mg2+) in the zeolite have neutralizing effects which causes the pH of the stormwater to increase, making it alkaline and consequently reducing the solubility of Zn and Cu. These three materials also possess high ion exchange capacity which allows them to adsorb large quantities of dissolved heavy metals. To evaluate the effectiveness of a downpipe treatment system containing limestone, zeolite and/or mussel shells in reducing the percentage of dissolved Zn and Cu from roof-runoff, both laboratory and field experiments were conducted. The laboratory experiments were done in two phases. Phase I consisted of batch experiments which assessed the dissolved Zn and Cu removal capacity of the three treatment materials at a grade of ≥ 1.18 ≤ 2.36 mm. Phase II was laboratory column treatment systems that were evaluated to quantify the hydraulic performance and dissolved Zn and Cu reduction capacity of each treatment material at two material depths (0.5 m and 1 m), two flow rates (1 L/min and 3 L/min) and when the materials were disturbed and undisturbed. For the laboratory column experiments, the untreated concentration of dissolved Zn and Cu from the roof-runoff ranged from 150-254 µg/L and 312-884 µg/L respectively. For the field experiments, Zn and Cu ranged from 406-2262 µg/L and 455-2581 µg/L respectively. The concentration of dissolved Zn and Cu in the untreated roof-runoff was considerably higher than ANZECC’s mixed instream guideline values for the protection of 90% of freshwater organisms of 15 µg/L and 1.18 µg/L for total Zn and Cu respectively. Evaluation of the percentage of dissolved Zn and Cu in the untreated roof-runoff from the laboratory column experiment showed that 100% of the Zn was in the dissolved form while dissolved Cu ranged from 78%-91%. These results indicate that Zn and Cu in roof-runoff is present mainly in the dissolved form which is ecotoxic to freshwater organisms. For the batch experiments, the percentage reduction of dissolved Zn and Cu varied. Limestone gave the highest mean percentage reduction for both Zn and Cu (87% Zn and 91% Cu) followed by mussel shells (78% Zn and 64% Cu) and then zeolite (48 % Zn and 64% Cu). However, for the laboratory column experiments, the amount of dissolved Zn and Cu removed by zeolite, limestone and mussel shells was not significantly different (p≤ 0.05). A reduction of 95-99% in dissolved Zn was achieved by all treatment materials at both depths, flow rates and disturbances while all three treatment materials only achieved 90-98% reduction in dissolved Cu at an undisturbed depth of 1 m. In the laboratory column experiments, all three treatment materials reduced dissolved Zn to concentrations well below ANZECC’s mixed instream guideline of 15 µg/L total Zn for the protection of 90% of freshwater organism’s. Although the reduction in dissolved Cu was not below ANZECC’s 90% mixed instream guideline of 1.8 µg/L total Cu, it was reduced to concentrations below 20 µg/L which was considerably lower than the 312 µg/L – 884 µg/L Cu present in the untreated roof-runoff. Dilution of the treated roof-runoff is expected as it moves downstream which would lead to further reduction in the concentration of dissolved Cu. The field experiment was conducted to collect data on the performance of the treatment system that would help improve the system design. Therefore, only mussel shells at an undisturbed depth of 1 m was evaluated. For the field experiment, dissolved Zn in runoff from the galvanized roof was reduced by 82-97% while dissolved Cu in runoff from the copper roof was reduced by 86-98%. These field results were comparable to what was obtained in the laboratory column experiments for mussel at an undisturbed depth of 1 m. These results show that the downpipe treatment system is robust and only small alterations to the system design would be required. From the laboratory column experiments, it was evident that adsorption and ion exchange was the main mechanism by which zeolite reduced the concentration of dissolved Zn and Cu. This is because there was no significant difference between the pH of the untreated roof-runoff and runoff treated by zeolite, however, dissolved Zn and Cu was reduced by >95% for the laboratory column experiments. It was also evident that neutralization contributed to the reduction of dissolved Zn and Cu in runoff treated by limestone and mussel shells in the batch experiments because a greater percentage reduction in dissolved Zn and Cu was observed at higher pH values. The use of zeolite, limestone and mussel shells were found to be very effective in removing dissolved Zn and Cu from roof-runoff in the laboratory column experiments. Mussel shell was then selected for field trials because it is a low cost and readily available waste product that proved to be just as effective as zeolite and limestone in the laboratory column experiments at removing dissolved Zn and Cu. The downpipe treatment system proved to be very effective under field conditions with >80% reduction in dissolved Zn and Cu achieved across each sampled rainfall event. These results show that factors such as the natural variation of untreated runoff quality that occurs under field conditions seem to have little influence on the Zn and Cu reduction efficiency of mussel shells which is an indication that the downpipe treatment system is effective and robust. Overall, this research contributes scientific understanding of a new stormwater treatment device that has the potential to achieve considerable reduction in dissolved Zn and Cu from roof-runoff that can be easily maintained and installed in urban areas with limited space.Publication Open Access Evaluation of community preferences for decentralised water management systems: a case study in Akaroa, Banks Peninsula(Lincoln University, 2017-10-03) Sun, HanLimitations on the supply of fresh water and increasing demand for council supplied water have become major issues in Akaroa, a tourist town on the Banks Peninsula approximately 80 kilometres from Christchurch City. Restrictions on domestic water use in the summer and new requirements for decentralised water management systems for new construction have been used to alleviate the burden of town water supply. Rainwater harvesting systems (RWHS) and greywater reuse system (GWRS) both represent potential options to decentralise the current water supply even further. This study informs the ongoing debate about water allocation on the Banks Peninsula by conducting a choice experiment (CE) to evaluate Akaroa homeowners’ preferences for installing these systems. Primary data was collected from Akaroa residents, and a latent class model was specified to estimate willingness to pay (WTP) for decentralised water supply systems. Results reveal that approximately two-thirds of the sample actually had a negative WTP for decentralised systems (range from -$3,145 to -$1,672), while WTP estimates for the remaining respondents ranged from $1,912 to $2,749. For both of these groups, subsidies will be required to encourage the adoption of all types of systems. Identification of the factors that affect latent class membership could be a focus for further studies.Publication Restricted Dairy farmers’ perspectives of riparian corridor design and management: a Canterbury, New Zealand, case study(Lincoln University, 2016-06-30) Mark, AbigailRiparian corridors provide many functions in agricultural landscapes which contribute to water quality and ecological values. However intensification of dairy farms has degraded waterways and their functions within many regions of New Zealand. Waterways have been left unfenced and accessible to stock, which has led to increased sedimentation and contamination of surface water, and the loss of other riparian functions that rely on vegetation and clean water such as biodiversity, fishing, swimming, food gathering, and recreational activities. Increasing attention upon these issues both in the media and in public policy, and the perceived need to protect the reputation of the New Zealand dairy industry, has led dairy companies, regional councils and non-governmental organizations to develop voluntary agri-environmental programmes that encourage farmer suppliers of dairy companies to exclude stock from riparian corridors (including from main crossing points) and to progressively plant some of their riparian corridors. There have been surveys of progress towards targets set by these programmes, but little is known about farmers’ first hand experiences of the design and management of their riparian corridors. Through key informant interviews with farmers in a Canterbury case study, this research describes how dairy farmers are designing and managing their riparian corridors, and evaluates their effectiveness for meeting dairy farmer, regulatory and industry expectations.