title: Catchment and lake water quality modelling to assess management options for Lake Rerewhakaaitu

authors: Cho, Eunju

abstract: Lake Rerewhakaaitu in the Bay of Plenty Region of North Island, has one of the most intensively farmed lake catchments in New Zealand. Nitrate concentrations in two surface stream inflows to the lake show substantial and statistically significant increases, between 1995 and 2015, however, lake water quality has remained relatively stable. The lake is polymictic (i.e., it mixes frequently) and is partly perched, with an effective hydrological catchment of approximately 10% of the surface topographic catchment. We used the hydrodynamic-ecological model DYRESM-CAEDYM to examine the relationship between inflow quantity and quality, and lake water quality. A groundwater model (MODFLOW) provided groundwater discharge values from the hydrologically effective catchment, to the lake model (DYRESM-CAEDYM). The model successfully reproduced the magnitude and dynamics of field measurements, as evidenced by low statistical error. Based on a novel uncertainty analysis that allows for assessment of forcing factors that contribute to model error, a component of the statistical error was identified to be due to lake water level variations, which was attributed to ecological changes in the littoral (shallow-water) zone of the lake. The calibrated model was used with a set of scenarios to examine land use change within the effective hydrological catchment, as well as climate change. Establishment of the lake model was subject to several areas of substantial uncertainty, including derivation of stream inflows by statistical modelling (rather than direct observation), hydrological uncertainty with regard to drainage pathways in the lake catchment, and reliability of some nutrient measurements in the lake and streams. Nevertheless, the present model can be considered among the most sophisticated tools available with which to inform lake management decisions. Model results suggest that improved land management efforts within the wider topographic catchment will have only minor impacts on Lake Rerewhakaaitu water quality, but within the hydrologically effective catchment land use improvements to decrease losses of nitrogen and phosphorus to the lake will be important. Maintaining and/or enhancing the forested area within the hydrologically effective catchment and potentially retiring (to indigenous vegetation) some of the area, as well as maintaining the riparian buffer of the lake, will help to maintain water quality of Lake Rerewhakaaitu. The model predicted that a future warmer climate would likely increase the duration of temperature stratification in the water column, leading to more deoxygenation of bottom waters and a decline in water quality. Offsetting this with maintaining and enhancing vegetation in the riparian area and hydrologically effective catchment may help to offset these effects.

text: Catchment and lake water quality modelling to assess management options for Lake Rerewhakaaitu Lake Rerewhakaaitu in the Bay of Plenty Region of North Island, has one of the most intensively farmed lake catchments in New Zealand. Nitrate concentrations in two surface stream inflows to the lake show substantial and statistically significant increases, between 1995 and 2015, however, lake water quality has remained relatively stable. The lake is polymictic (i.e., it mixes frequently) and is partly perched, with an effective hydrological catchment of approximately 10% of the surface topographic catchment. We used the hydrodynamic-ecological model DYRESM-CAEDYM to examine the relationship between inflow quantity and quality, and lake water quality. A groundwater model (MODFLOW) provided groundwater discharge values from the hydrologically effective catchment, to the lake model (DYRESM-CAEDYM). The model successfully reproduced the magnitude and dynamics of field measurements, as evidenced by low statistical error. Based on a novel uncertainty analysis that allows for assessment of forcing factors that contribute to model error, a component of the statistical error was identified to be due to lake water level variations, which was attributed to ecological changes in the littoral (shallow-water) zone of the lake. The calibrated model was used with a set of scenarios to examine land use change within the effective hydrological catchment, as well as climate change. Establishment of the lake model was subject to several areas of substantial uncertainty, including derivation of stream inflows by statistical modelling (rather than direct observation), hydrological uncertainty with regard to drainage pathways in the lake catchment, and reliability of some nutrient measurements in the lake and streams. Nevertheless, the present model can be considered among the most sophisticated tools available with which to inform lake management decisions. Model results suggest that improved land management efforts within the wider topographic catchment will have only minor impacts on Lake Rerewhakaaitu water quality, but within the hydrologically effective catchment land use improvements to decrease losses of nitrogen and phosphorus to the lake will be important. Maintaining and/or enhancing the forested area within the hydrologically effective catchment and potentially retiring (to indigenous vegetation) some of the area, as well as maintaining the riparian buffer of the lake, will help to maintain water quality of Lake Rerewhakaaitu. The model predicted that a future warmer climate would likely increase the duration of temperature stratification in the water column, leading to more deoxygenation of bottom waters and a decline in water quality. Offsetting this with maintaining and enhancing vegetation in the riparian area and hydrologically effective catchment may help to offset these effects.

year: 2020

title: Dusty horizons

authors: Lowe, David J.

abstract: Dust whipped up and deposited by wind forms sheets of loess, which drape over the land. These loess deposits and the soils formed within them yield insights into past climatic and environmental change.

text: Dusty horizons Dust whipped up and deposited by wind forms sheets of loess, which drape over the land. These loess deposits and the soils formed within them yield insights into past climatic and environmental change.

year: 2015

title: An Evaluation of an Impaired Driver Treatment Programme Facilitated by Tūhoe Hauora

authors: Waru, Nicole Arihia

subjects: Tuhoe Hauora

abstract: Driving while impaired is a substantial issue in Aotearoa.  It has the potential to result in loss of life and cause significant health and economic strain on society.  Recidivist impaired drivers are major contributors to this problem.  Countermeasures of impaired driving have previously included liquor licencing, drinking age restrictions, health promotion campaigns and health rehabilitation therapies.  The Ministry of Health offer an Impaired Driving therapy throughout Aotearoa as countermeasure to this issue.  The programme is administered through the funder-contract system. Participation is compulsory for those mandated by court order.  
This study evaluates an Impaired Driver programme facilitated by Tūhoe Hauora; a kaupapa Māori mental health and addiction provider based in Taneatua, Eastern Bay of Plenty.  The course is delivered once weekly over a period of ten weeks to a group of twelve or less recidivist impaired drivers or first time offenders who were convicted of driving with excessive levels of breath alcohol.    
The evaluation draws from a community psychology paradigm in exploration of the lived experiences of programme participants, in the context of course 2 of the 2014 Tūhoe Hauora Impaired Driving course.  
The experiences of five individuals were explored using in-depth face to face interviews and presented using a case-by-case approach.  Participant observation, document review, evaluation visits and participant surveys were used as supplement methods of inquiry.  The findings illustrated that Tūhoe Hauora met contract requirements by addressing impaired driving recidivism to date of interview.  The evaluation also found the course actualising the mission of Tūhoe Hauora which was to address the holistic well-being of programme participants.  The research did present areas in the programme that could be improved particularly pertaining to the referral process and a need for agency collaboration.  Recommendations were formulated in attempt to address the programme gaps and discussion is offered in addressing the multi-layered oppression that was experienced throughout the evaluation process by both Tūhoe Hauora and the evaluation participants.

text: An Evaluation of an Impaired Driver Treatment Programme Facilitated by Tūhoe Hauora Driving while impaired is a substantial issue in Aotearoa.  It has the potential to result in loss of life and cause significant health and economic strain on society.  Recidivist impaired drivers are major contributors to this problem.  Countermeasures of impaired driving have previously included liquor licencing, drinking age restrictions, health promotion campaigns and health rehabilitation therapies.  The Ministry of Health offer an Impaired Driving therapy throughout Aotearoa as countermeasure to this issue.  The programme is administered through the funder-contract system. Participation is compulsory for those mandated by court order.  
This study evaluates an Impaired Driver programme facilitated by Tūhoe Hauora; a kaupapa Māori mental health and addiction provider based in Taneatua, Eastern Bay of Plenty.  The course is delivered once weekly over a period of ten weeks to a group of twelve or less recidivist impaired drivers or first time offenders who were convicted of driving with excessive levels of breath alcohol.    
The evaluation draws from a community psychology paradigm in exploration of the lived experiences of programme participants, in the context of course 2 of the 2014 Tūhoe Hauora Impaired Driving course.  
The experiences of five individuals were explored using in-depth face to face interviews and presented using a case-by-case approach.  Participant observation, document review, evaluation visits and participant surveys were used as supplement methods of inquiry.  The findings illustrated that Tūhoe Hauora met contract requirements by addressing impaired driving recidivism to date of interview.  The evaluation also found the course actualising the mission of Tūhoe Hauora which was to address the holistic well-being of programme participants.  The research did present areas in the programme that could be improved particularly pertaining to the referral process and a need for agency collaboration.  Recommendations were formulated in attempt to address the programme gaps and discussion is offered in addressing the multi-layered oppression that was experienced throughout the evaluation process by both Tūhoe Hauora and the evaluation participants.

year: 2016