title: Lake Rotokakahi water quality modelling

authors: Jones, Hannah Frances Emily

abstract: Lake Rotokakahi is an iwi-owned lake, administered by the Lake Rotokakahi Board of Control. The lake has a surface area of 4.4 km2, a mean depth of 17.5 m, and a catchment of 19.7 km2 of which most is in exotic forest (46.5%), with some pasture (27.8%) and regenerating native forest and scrub (25.7%). Lake Rotokakahi has only one permanent surface inflow and it is assumed that the lake must be predominantly groundwater fed. The lake outflow, Te Wairoa Stream, flows into Lake Tarawera. Monitoring indicates that water quality has recently declined in the lake, with a shift from a mesotrophic state in the 1990's, to currently being classified as eutrophic. Increased algal biomass has reduced water clarity and in May 2011 the first ever recorded algae bloom of a toxic cyanobacterium species resulted in a fish kill in Te Wairoa Stream. With the majority of the catchment in either exotic or native forest, the cause for the decline in water quality is unclear. However there is some concern that forestry harvesting operations may lead to increased surface runoff of sediment and associated phosphorus in ephemeral streams that feed into the lake. The objective of this study was to setup a water quality model for Lake Rotokakahi, which in the future may provide a decisionsupport tool for lake managers.
The model used, DYRESM-CAEDYM, is a one-dimensional (1D) coupled hydrodynamic-water quality model that has been widely used in New Zealand and overseas. Methodology for deriving model forcing data (e.g. meteorological data, inflow volumes and nutrient loads), including the application of catchment and lake water balances, is described in this report. The catchment water balance indicates that groundwater and rainfall account for 37% and 42%, respectively, of the total inflow volume to the lake, with surface and ephemeral inflows contributing a smaller proportion (c. 20% combined). Furthermore, it appears that groundwater contributes a significant proportion (c. 60 - 70%) of the total nutrient loads, although surface and ephemeral inflows also contribute a significant proportion (34%) of the total phosphorus load. It should be noted that the catchment water balance is based on a very limited dataset, and therefore subject to significant uncertainty. 
We simulated the period July 2009 to June 2012 with DYRESM-CAEDYM. Model performance statistics indicated reasonable simulation of water quality for the calibration period, but did not satisfactorily capture the magnitude and dynamics of chlorophyll a and some nutrient species over an independent model validation period. There may be a number of reasons for the poor model performance over the validation period. For example, it may be that zooplankton and/or freshwater mussels (kakahi), which were not included in the model configuration, may exert significant grazing pressure on the phytoplankton populations at certain times. Furthermore, the significant uncertainty in the catchment water and nutrient loads most likely will have affected model performance. Nutrient concentrations are routinely monitored only in the surface inflow. There are no measurements of nutrient and sediment loads in ephemeral streams, and there is very limited data on groundwater nutrient concentrations.
In its current form, the DYRESM-CAEDYM model is not suitable for scenario testing of lake management options. It is recommended that effort is directed at quantification of ephemeral and groundwater inflows and their associated nutrient and (particularly for ephemeral inflows) sediment loads. This may be particularly important for ephemeral inflows located close to the lake that may be influenced by forestry harvesting operations. Recent increases in measured total phosphorus and phosphate concentrations in the surface inflow and in the lake, combined with the degradation of water quality that has already occurred over the last 20 years, provides further impetus for addressing this critical information gap. Were new data to  become available, opportunities exist for improving the performance of the current model and for developing a three-dimensional coupled hydrodynamic-water quality model (e.g. ELCOM-CAEDYM) with representation of kakahi and/or zooplankton, which may be able to resolve questions pertinent to the functioning of the lake, and to lake and catchment management.

text: Lake Rotokakahi water quality modelling Lake Rotokakahi is an iwi-owned lake, administered by the Lake Rotokakahi Board of Control. The lake has a surface area of 4.4 km2, a mean depth of 17.5 m, and a catchment of 19.7 km2 of which most is in exotic forest (46.5%), with some pasture (27.8%) and regenerating native forest and scrub (25.7%). Lake Rotokakahi has only one permanent surface inflow and it is assumed that the lake must be predominantly groundwater fed. The lake outflow, Te Wairoa Stream, flows into Lake Tarawera. Monitoring indicates that water quality has recently declined in the lake, with a shift from a mesotrophic state in the 1990's, to currently being classified as eutrophic. Increased algal biomass has reduced water clarity and in May 2011 the first ever recorded algae bloom of a toxic cyanobacterium species resulted in a fish kill in Te Wairoa Stream. With the majority of the catchment in either exotic or native forest, the cause for the decline in water quality is unclear. However there is some concern that forestry harvesting operations may lead to increased surface runoff of sediment and associated phosphorus in ephemeral streams that feed into the lake. The objective of this study was to setup a water quality model for Lake Rotokakahi, which in the future may provide a decisionsupport tool for lake managers.
The model used, DYRESM-CAEDYM, is a one-dimensional (1D) coupled hydrodynamic-water quality model that has been widely used in New Zealand and overseas. Methodology for deriving model forcing data (e.g. meteorological data, inflow volumes and nutrient loads), including the application of catchment and lake water balances, is described in this report. The catchment water balance indicates that groundwater and rainfall account for 37% and 42%, respectively, of the total inflow volume to the lake, with surface and ephemeral inflows contributing a smaller proportion (c. 20% combined). Furthermore, it appears that groundwater contributes a significant proportion (c. 60 - 70%) of the total nutrient loads, although surface and ephemeral inflows also contribute a significant proportion (34%) of the total phosphorus load. It should be noted that the catchment water balance is based on a very limited dataset, and therefore subject to significant uncertainty. 
We simulated the period July 2009 to June 2012 with DYRESM-CAEDYM. Model performance statistics indicated reasonable simulation of water quality for the calibration period, but did not satisfactorily capture the magnitude and dynamics of chlorophyll a and some nutrient species over an independent model validation period. There may be a number of reasons for the poor model performance over the validation period. For example, it may be that zooplankton and/or freshwater mussels (kakahi), which were not included in the model configuration, may exert significant grazing pressure on the phytoplankton populations at certain times. Furthermore, the significant uncertainty in the catchment water and nutrient loads most likely will have affected model performance. Nutrient concentrations are routinely monitored only in the surface inflow. There are no measurements of nutrient and sediment loads in ephemeral streams, and there is very limited data on groundwater nutrient concentrations.
In its current form, the DYRESM-CAEDYM model is not suitable for scenario testing of lake management options. It is recommended that effort is directed at quantification of ephemeral and groundwater inflows and their associated nutrient and (particularly for ephemeral inflows) sediment loads. This may be particularly important for ephemeral inflows located close to the lake that may be influenced by forestry harvesting operations. Recent increases in measured total phosphorus and phosphate concentrations in the surface inflow and in the lake, combined with the degradation of water quality that has already occurred over the last 20 years, provides further impetus for addressing this critical information gap. Were new data to  become available, opportunities exist for improving the performance of the current model and for developing a three-dimensional coupled hydrodynamic-water quality model (e.g. ELCOM-CAEDYM) with representation of kakahi and/or zooplankton, which may be able to resolve questions pertinent to the functioning of the lake, and to lake and catchment management.

year: 2014

title: Lost in translation or lack of nuance? Perception of (near-)synonymy of common te reo Māori loanwords in New Zealand English

authors: Pohl, Alexander

abstract: Ongoing contact between languages and their speakers inevitably leads to a flow of words being borrowed from one language into another. Research in the field of language contact has established and documented the kinds of borrowed words that stick in their recipient language (Haspelmath 2009; Winford 2010). However, one question that has received comparatively less attention is how a newly adopted loanword relates to the structure of the existing lexicon it enters. In recent years, language contact research has thus seen a paradigm shift towards an onomasiological perspective (see Anderson et al. 2017; Crombez et al. 2022; Zenner et al. 2023). Within this approach, most studies looking at lexical variation between loanwords and their (near-)synonyms employ corpus linguistics methods (e.g. Onysko & Winter-Froemel 2011; Soares da Silva 2013). However, there is variation in how these corpus studies have investigated loanword meanings, and, to our knowledge, there has been almost no experimental research focussed specifically on the relationship between loanwords and their (near-)synonyms to date. This project presents a large-scale experimental approach from a case-study examining Māori loanwords borrowed into New Zealand English (NZE). NZE presents an unusual language contact situation because it involves a dominant language (NZE) receiving an exceptionally high amount of lexical material (words and phrases) from an Indigenous language: Māori. Further adding to the uniqueness of this contact situation is the fact that only a fraction of the population (<10%) speaks Māori fluently (Statistics New Zealand 2019). Nonetheless, Māori loanwords are ubiquitous, salient, and probably still increasing within the NZE lexicon (Macalister 2007; Trye et al. 2019). One important dimension of this set of borrowings are their semantic characteristics, which straddle three main classes of words: flora and fauna (mānuka ‘tea tree’), material culture (maunga ‘mountain’) and social culture (mana ‘power’).  Here, we report on a Qualtrics experiment devised to probe the perceived relationship between 60 Māori loanwords and their NZE equivalents, as ascertained from published sources. The synonymy judgements were elicited for pairs (e.g. whānau – family) using an analogue slider (ranging from 0 = non-synonymous to 100 = fully synonymous). Data was collected using a three-tiered questionnaire: 1) assessing synonymy of loanwords; 2) eliciting strategies for semantic assessments; and 3) collating background information about participants. Following cleaning and exclusions, the dataset showed a skew towards female participants, and for this reason, we focus our statistical analysis on the core sample containing (n = 170) young women (18-24 years). The results of the synonymy judgements analysis consist of qualitative inspections of box plots in relation to the semantic characteristics of Māori words in question, as well as sociodemographic variables of interest, specifically: years lived in Aotearoa NZ, and a composite score capturing exposure to and attitude towards Māori (TRMO). Preliminary findings suggest that many people think Māori loanwords are (highly) synonymous with NZE lexical alternatives. Our regression analyses exhibit evidence that years lived in Aotearoa NZ (p = 0.0054) and TRMO (p = 8.26e-10) can predict knowledge of Māori words. No statistically significant evidence was found for any predictors regarding the scores of the synonymy judgements; instead, we found that the random effects account for most of the variation. This is indicative of idiosyncratic loanword behaviour, in line with situations where variation is in-flux. These findings will be complemented by qualitative analyses of comments provided by participants in the open answer section (2). The talk will conclude with a summary of contributions to the general understanding of loanword meanings and contact-induced lexical change.

text: Lost in translation or lack of nuance? Perception of (near-)synonymy of common te reo Māori loanwords in New Zealand English Ongoing contact between languages and their speakers inevitably leads to a flow of words being borrowed from one language into another. Research in the field of language contact has established and documented the kinds of borrowed words that stick in their recipient language (Haspelmath 2009; Winford 2010). However, one question that has received comparatively less attention is how a newly adopted loanword relates to the structure of the existing lexicon it enters. In recent years, language contact research has thus seen a paradigm shift towards an onomasiological perspective (see Anderson et al. 2017; Crombez et al. 2022; Zenner et al. 2023). Within this approach, most studies looking at lexical variation between loanwords and their (near-)synonyms employ corpus linguistics methods (e.g. Onysko & Winter-Froemel 2011; Soares da Silva 2013). However, there is variation in how these corpus studies have investigated loanword meanings, and, to our knowledge, there has been almost no experimental research focussed specifically on the relationship between loanwords and their (near-)synonyms to date. This project presents a large-scale experimental approach from a case-study examining Māori loanwords borrowed into New Zealand English (NZE). NZE presents an unusual language contact situation because it involves a dominant language (NZE) receiving an exceptionally high amount of lexical material (words and phrases) from an Indigenous language: Māori. Further adding to the uniqueness of this contact situation is the fact that only a fraction of the population (<10%) speaks Māori fluently (Statistics New Zealand 2019). Nonetheless, Māori loanwords are ubiquitous, salient, and probably still increasing within the NZE lexicon (Macalister 2007; Trye et al. 2019). One important dimension of this set of borrowings are their semantic characteristics, which straddle three main classes of words: flora and fauna (mānuka ‘tea tree’), material culture (maunga ‘mountain’) and social culture (mana ‘power’).  Here, we report on a Qualtrics experiment devised to probe the perceived relationship between 60 Māori loanwords and their NZE equivalents, as ascertained from published sources. The synonymy judgements were elicited for pairs (e.g. whānau – family) using an analogue slider (ranging from 0 = non-synonymous to 100 = fully synonymous). Data was collected using a three-tiered questionnaire: 1) assessing synonymy of loanwords; 2) eliciting strategies for semantic assessments; and 3) collating background information about participants. Following cleaning and exclusions, the dataset showed a skew towards female participants, and for this reason, we focus our statistical analysis on the core sample containing (n = 170) young women (18-24 years). The results of the synonymy judgements analysis consist of qualitative inspections of box plots in relation to the semantic characteristics of Māori words in question, as well as sociodemographic variables of interest, specifically: years lived in Aotearoa NZ, and a composite score capturing exposure to and attitude towards Māori (TRMO). Preliminary findings suggest that many people think Māori loanwords are (highly) synonymous with NZE lexical alternatives. Our regression analyses exhibit evidence that years lived in Aotearoa NZ (p = 0.0054) and TRMO (p = 8.26e-10) can predict knowledge of Māori words. No statistically significant evidence was found for any predictors regarding the scores of the synonymy judgements; instead, we found that the random effects account for most of the variation. This is indicative of idiosyncratic loanword behaviour, in line with situations where variation is in-flux. These findings will be complemented by qualitative analyses of comments provided by participants in the open answer section (2). The talk will conclude with a summary of contributions to the general understanding of loanword meanings and contact-induced lexical change.

year: 2024

title: Limited role of climate change in extreme low rainfall associated with southern Madagascar food insecurity, 2019–21

authors: Harrington, Luke J.

abstract: Southern Madagascar recently experienced a severe food security crisis, made significantly worse by well below average rainfall from July 2019 to June 2021. This exceptional drought has affected a region with high pre-existing levels of vulnerability to food insecurity (subsistence agriculture and pastoralism in the region is rain-fed only), while impacts have been compounded further by COVID-19 restrictions and pest infestations. The rainy seasons of both 2019/20 and 2020/21 saw just 60% of normal rainfall across the Grand South region and was estimated as a 1-in-135 year dry event, only surpassed in severity by the devastating drought of 1990–92. Based on a combination of observations and climate modelling, the likelihood of experiencing such poor rains in the region was not significantly increased due to human-caused climate change: while the observations and models combine to indicate a small shift toward more droughts like the 2019–2021 event as a consequence of climate change, these trends remain overwhelmed by natural variability. This result is consistent with previous research, with the Intergovernmental Panel on Climate Change (IPCC)'s Sixth Assessment Report concluding that any perceptible changes in drought will only emerge in this region if global mean temperatures exceed 2 °C above pre-industrial levels.

text: Limited role of climate change in extreme low rainfall associated with southern Madagascar food insecurity, 2019–21 Southern Madagascar recently experienced a severe food security crisis, made significantly worse by well below average rainfall from July 2019 to June 2021. This exceptional drought has affected a region with high pre-existing levels of vulnerability to food insecurity (subsistence agriculture and pastoralism in the region is rain-fed only), while impacts have been compounded further by COVID-19 restrictions and pest infestations. The rainy seasons of both 2019/20 and 2020/21 saw just 60% of normal rainfall across the Grand South region and was estimated as a 1-in-135 year dry event, only surpassed in severity by the devastating drought of 1990–92. Based on a combination of observations and climate modelling, the likelihood of experiencing such poor rains in the region was not significantly increased due to human-caused climate change: while the observations and models combine to indicate a small shift toward more droughts like the 2019–2021 event as a consequence of climate change, these trends remain overwhelmed by natural variability. This result is consistent with previous research, with the Intergovernmental Panel on Climate Change (IPCC)'s Sixth Assessment Report concluding that any perceptible changes in drought will only emerge in this region if global mean temperatures exceed 2 °C above pre-industrial levels.

year: 2022-12-01