title: Measurements and modelling of eutrophication processes in Lake Rotoiti, New Zealand

authors: von Westernhagen, Nina

subjects: 3D modelling

abstract: Deterioration of water quality is a common problem for aquatic systems globally, which is accelerated by factors such as urban settlement, farming, forestry and recreation. Spatial variability of water quality in these systems hinders a more advanced understanding of their dynamics, to better enable strategies to be developed to combat their deterioration. Understanding the drivers for spatial variability is fundamentally important for predicting how lake ecosystems will respond to management scenarios and which management actions are most likely to be successful to improve lake health. Through a field study in a morphologically diverse lake in New Zealand, and the application of a lake ecosystem model, this study examined the spatial and temporal variability of phytoplankton biomass and made a detailed consideration of the performance of three-dimensional lake ecosystem models. To gain insight in the spatial variability in phytoplankton productivity, surface phytoplankton productivity measurements were carried out at three stations in morphologically complex Lake Rotoiti, North Island, New Zealand, with the objective of defining variations between sites and seasons, and the dominant environmental drivers of these variations. There was no overarching statistical relationship between measured environmental variables and primary productivity or specific production. Inorganic nutrient concentrations at the surface of the shallow station were low throughout the whole year but at the other two stations they showed a typical pattern for monomictic lakes of higher levels during winter mixing and declining concentrations during thermal stratification. The high variability between the three sites indicates that it is important to account for local differences in productivity in morphologically diverse lakes, and that whole-lake productivity estimates may vary greatly depending on the location and depth at which measurements are made. To gain understanding of the spatial variability, a higher resolution three-dimensional (3D) model, ELCOM-CAEDYM, was used to simulate the time-varying horizontal and vertical variations in water quality over one year (May 2004-May 2005). The main inflow to Lake Rotoiti arises via the Ohau Channel from adjacent eutrophic Lake Rotorua. Highly spatially resolved field data were collected monthly to validate the model performance for simulations of temperature, dissolved oxygen and chlorophyll a. The model was configured to simulate a geothermal heat source in the deepest part of the main lake basin. Model simulations of temperature, dissolved oxygen and chlorophyll a were highly correlated with measurements of these variables but simulations of spatial variations in nutrient concentration showed relatively low correlation coefficient values, in particular at a station located in a shallow embayment. An examination of the behaviour of a conservative tracer introduced into the major inflow of Lake Rotoiti, the Ohau Channel, confirmed previous findings that this inflow could enter the lake as a surface inflow, interflow or underflow, depending on temperature gradients between the inflow and the lake water column. The results showed that ELCOM-CAEDYM is capable of reproducing highly spatially resolved field data in a complex, geothermally-influenced lake, and can provide important insights into the fate of heat and constituents in major inflows. A wall to divert Ohau Channel water directly towards the outflow of Lake Rotoiti was implemented in August 2008. Based on parameter values calibrated for the time period before the inflow diversion (May 2004-May 2005), ELCOM-CAEDYM was applied to the post-diversion wall period of August 2008-August 2009. The model showed good fit with observed data for temperature, dissolved oxygen and chlorophyll a, but the model showed a poor fit when simulations were compared with in situ nutrient concentrations at all stations. Simulations with ELCOM-CAEDYM suggest that model accuracy may be improved when a simplified dynamic sediment diagenesis model is available. This could provide for less sensitivity to sediment nutrient release rates of the model and better model fit to in situ data. Ecosystem modelling is likely to play an increasingly important role in lake management and scientific understanding of lake processes as computer speed increases and models undergo further refinements. The model development is in a phase of relative maturity in which water quality simulations provide an efficient and rational tool to compare water quality outcomes and cost effectiveness of lake improvement techniques, to provide for preservation and improvement in water quality in the future.

text: Measurements and modelling of eutrophication processes in Lake Rotoiti, New Zealand Deterioration of water quality is a common problem for aquatic systems globally, which is accelerated by factors such as urban settlement, farming, forestry and recreation. Spatial variability of water quality in these systems hinders a more advanced understanding of their dynamics, to better enable strategies to be developed to combat their deterioration. Understanding the drivers for spatial variability is fundamentally important for predicting how lake ecosystems will respond to management scenarios and which management actions are most likely to be successful to improve lake health. Through a field study in a morphologically diverse lake in New Zealand, and the application of a lake ecosystem model, this study examined the spatial and temporal variability of phytoplankton biomass and made a detailed consideration of the performance of three-dimensional lake ecosystem models. To gain insight in the spatial variability in phytoplankton productivity, surface phytoplankton productivity measurements were carried out at three stations in morphologically complex Lake Rotoiti, North Island, New Zealand, with the objective of defining variations between sites and seasons, and the dominant environmental drivers of these variations. There was no overarching statistical relationship between measured environmental variables and primary productivity or specific production. Inorganic nutrient concentrations at the surface of the shallow station were low throughout the whole year but at the other two stations they showed a typical pattern for monomictic lakes of higher levels during winter mixing and declining concentrations during thermal stratification. The high variability between the three sites indicates that it is important to account for local differences in productivity in morphologically diverse lakes, and that whole-lake productivity estimates may vary greatly depending on the location and depth at which measurements are made. To gain understanding of the spatial variability, a higher resolution three-dimensional (3D) model, ELCOM-CAEDYM, was used to simulate the time-varying horizontal and vertical variations in water quality over one year (May 2004-May 2005). The main inflow to Lake Rotoiti arises via the Ohau Channel from adjacent eutrophic Lake Rotorua. Highly spatially resolved field data were collected monthly to validate the model performance for simulations of temperature, dissolved oxygen and chlorophyll a. The model was configured to simulate a geothermal heat source in the deepest part of the main lake basin. Model simulations of temperature, dissolved oxygen and chlorophyll a were highly correlated with measurements of these variables but simulations of spatial variations in nutrient concentration showed relatively low correlation coefficient values, in particular at a station located in a shallow embayment. An examination of the behaviour of a conservative tracer introduced into the major inflow of Lake Rotoiti, the Ohau Channel, confirmed previous findings that this inflow could enter the lake as a surface inflow, interflow or underflow, depending on temperature gradients between the inflow and the lake water column. The results showed that ELCOM-CAEDYM is capable of reproducing highly spatially resolved field data in a complex, geothermally-influenced lake, and can provide important insights into the fate of heat and constituents in major inflows. A wall to divert Ohau Channel water directly towards the outflow of Lake Rotoiti was implemented in August 2008. Based on parameter values calibrated for the time period before the inflow diversion (May 2004-May 2005), ELCOM-CAEDYM was applied to the post-diversion wall period of August 2008-August 2009. The model showed good fit with observed data for temperature, dissolved oxygen and chlorophyll a, but the model showed a poor fit when simulations were compared with in situ nutrient concentrations at all stations. Simulations with ELCOM-CAEDYM suggest that model accuracy may be improved when a simplified dynamic sediment diagenesis model is available. This could provide for less sensitivity to sediment nutrient release rates of the model and better model fit to in situ data. Ecosystem modelling is likely to play an increasingly important role in lake management and scientific understanding of lake processes as computer speed increases and models undergo further refinements. The model development is in a phase of relative maturity in which water quality simulations provide an efficient and rational tool to compare water quality outcomes and cost effectiveness of lake improvement techniques, to provide for preservation and improvement in water quality in the future.

year: 2010

title: An Investigation of the Macroeconomic and Monetary Effects of Dollarization in Eritrea

authors: Mengesha, Lula G.

subjects: Dollarization

abstract: Most countries of the developing world have voluntarily or involuntarily been involved in using foreign currencies and trapped their economies for either the best or worst outcomes of dollarization. For those countries that have fully dollarized their economies, dollarization has provided some benefits in terms of bringing economic stability. However, the benefits in these economies came with costs that have worsened the income inequality and poverty that exist within their economies. Similarly, some countries that rely partially on their own currencies and partially on foreign currencies have seen different outcomes of partial dollarization.
	This research has specifically examined the reliance of the Eritrean economy on hard currency. Despite numerous studies that have been conducted regarding the Eritrean economy, the dollarization of Eritrea is an important issue that has not been investigated. This research has uncovered what kind of dollarization the Eritrean economy has and also what factors drive the Eritrean dollarization. It has been found that there is partial dollarization with evidence of financial, sovereign liability and underground dollarization in the economy. Real dollarization is only manifested in the form of selling houses and lands in exchange for hard currency. It has also been discovered that banking practices, the structure of the interest rate, loans issued to the private sector relative to the government sector and the Eritrean monetary system, particularly the introduction of new currency, followed by the second war with Ethiopia in 1998, are some of the causative factors. 
	Furthermore, this research has investigated the impact of partial dollarization of the Eritrean economy on macro-economic variables with specific examination on the exchange rate volatility, inflation and the monetary policy transmission mechanisms. In each analysis, quarterly data starting from 1996 to 2008 is employed. The fundamental reason for selecting this time period for the study is the inability to obtain the data for some of the variables outside the specified time period. Exponential Generalised Autoregressive Conditionally Heteroscedasticity in mean (EGARCH) model is applied over real official exchange rate and on both nominal as well as real black market exchange rates. Dollarization measured by a hard currency index is then augmented in the variance equation of EGARCH-M (1, 1). The results show that partial dollarization of the Eritrean economy enhances the volatility of the real official exchange rate, the nominal and the real black market exchange rates.
To see whether partial dollarization reduces or produces inflation in the Eritrean economy, Vector Error Correction Models together with Dynamic Ordinary Least Squares (DOLS) are employed. The results indicate that inflation increases as a result of an increase in dollarization. This applies regardless of whether official or black market exchange rate data are used in the estimation. In terms of the short-run dynamics involved in the long-run relationship between dollarization and inflation, the speed of adjustment towards long-run equilibrium ranges from 7.2-7.6 percent per quarter. Both error correction terms are negative. This indicates that the adjustment process is stable and convergent towards the long-run equilibrium which implies that there is a guaranteed long-run relationship between inflation and the remaining variables including dollarization.
To examine the effectiveness of the channels of the monetary policy, Vector Autoregressive (VAR), Structural Autoregressive (SVAR) and Toda and Yamamoto (TY) models have been used. The results suggest that there is an effective exchange rate channel through the black market, an ineffective credit channel through the credit issued to the private sector and an effective credit channel through the credit issued to the government.  
In general, the contribution of this study can be summarized in three different areas: first, the measurement of dollarization; second, the determinants of dollarization; third, the effects of dollarization. Some of the policy implications of the findings are first, the Bank of Eritrea should address its exchange rate policy by revisiting the current official exchange rate and, at the same time, by addressing the growth of the black market foreign exchange. The Bank of Eritrea should also address its regulation on banking practices and the structure of interest rates. Second, the bank should create a conducive environment for the private sector to promote economic growth and minimise excessive government expenditure which requires fiscal discipline. Third, there should be an effort made to pave the ways for economic and financial cooperation with neighbouring countries.

text: An Investigation of the Macroeconomic and Monetary Effects of Dollarization in Eritrea Most countries of the developing world have voluntarily or involuntarily been involved in using foreign currencies and trapped their economies for either the best or worst outcomes of dollarization. For those countries that have fully dollarized their economies, dollarization has provided some benefits in terms of bringing economic stability. However, the benefits in these economies came with costs that have worsened the income inequality and poverty that exist within their economies. Similarly, some countries that rely partially on their own currencies and partially on foreign currencies have seen different outcomes of partial dollarization.
	This research has specifically examined the reliance of the Eritrean economy on hard currency. Despite numerous studies that have been conducted regarding the Eritrean economy, the dollarization of Eritrea is an important issue that has not been investigated. This research has uncovered what kind of dollarization the Eritrean economy has and also what factors drive the Eritrean dollarization. It has been found that there is partial dollarization with evidence of financial, sovereign liability and underground dollarization in the economy. Real dollarization is only manifested in the form of selling houses and lands in exchange for hard currency. It has also been discovered that banking practices, the structure of the interest rate, loans issued to the private sector relative to the government sector and the Eritrean monetary system, particularly the introduction of new currency, followed by the second war with Ethiopia in 1998, are some of the causative factors. 
	Furthermore, this research has investigated the impact of partial dollarization of the Eritrean economy on macro-economic variables with specific examination on the exchange rate volatility, inflation and the monetary policy transmission mechanisms. In each analysis, quarterly data starting from 1996 to 2008 is employed. The fundamental reason for selecting this time period for the study is the inability to obtain the data for some of the variables outside the specified time period. Exponential Generalised Autoregressive Conditionally Heteroscedasticity in mean (EGARCH) model is applied over real official exchange rate and on both nominal as well as real black market exchange rates. Dollarization measured by a hard currency index is then augmented in the variance equation of EGARCH-M (1, 1). The results show that partial dollarization of the Eritrean economy enhances the volatility of the real official exchange rate, the nominal and the real black market exchange rates.
To see whether partial dollarization reduces or produces inflation in the Eritrean economy, Vector Error Correction Models together with Dynamic Ordinary Least Squares (DOLS) are employed. The results indicate that inflation increases as a result of an increase in dollarization. This applies regardless of whether official or black market exchange rate data are used in the estimation. In terms of the short-run dynamics involved in the long-run relationship between dollarization and inflation, the speed of adjustment towards long-run equilibrium ranges from 7.2-7.6 percent per quarter. Both error correction terms are negative. This indicates that the adjustment process is stable and convergent towards the long-run equilibrium which implies that there is a guaranteed long-run relationship between inflation and the remaining variables including dollarization.
To examine the effectiveness of the channels of the monetary policy, Vector Autoregressive (VAR), Structural Autoregressive (SVAR) and Toda and Yamamoto (TY) models have been used. The results suggest that there is an effective exchange rate channel through the black market, an ineffective credit channel through the credit issued to the private sector and an effective credit channel through the credit issued to the government.  
In general, the contribution of this study can be summarized in three different areas: first, the measurement of dollarization; second, the determinants of dollarization; third, the effects of dollarization. Some of the policy implications of the findings are first, the Bank of Eritrea should address its exchange rate policy by revisiting the current official exchange rate and, at the same time, by addressing the growth of the black market foreign exchange. The Bank of Eritrea should also address its regulation on banking practices and the structure of interest rates. Second, the bank should create a conducive environment for the private sector to promote economic growth and minimise excessive government expenditure which requires fiscal discipline. Third, there should be an effort made to pave the ways for economic and financial cooperation with neighbouring countries.

year: 2013

title: A case study of Pipiri Ki A Papatūānuku

authors: Tamoko-o-te-rangi, Ormsby

subjects: environmental initiatives

abstract: This thesis is an examination and analysis of the environmental initiative Pipiri Ki A Papatūānuku, co-founded by Waimirirangi Ormsby (née Koopu-Stone) and myself, Tamoko Ormsby. The primary aim of this research was to achieve an understanding of the PKP initiative at the individual level and to inform future collective action at the community level. As such, my primary research question is:

How can Pipiri Ki A Papatūānuku inform community-scale action that contributes to our more-than-human relationship with Papatūānuku within our current capitalist settler-colonial context?

The study is part-autoethnographic in that it is informed by my personal reflections and experiences as a co-founder, operator, and participant of the initiative. In addition, the study explores the number of participants who signed up yearly for each action and employs a brief descriptive analysis of the initiative.

The literature review explores how common Western notions of environmentalism are devoid of the spiritual, cultural, and relational aspects present within indigenous and Māori knowledge systems. It touches on the histories of capitalism and colonialism and how these have led to the consumptogenic society we are in. It aims to illustrate the nexus between the Māori and Western Eurocentric worlds.

He Whatu is the framework that has emerged from this case study as the means to respond to the primary research question. The framework was developed by analyzing the key themes of PKP over the years 2017 to 2021. He Whatu has five key elements: Identity, Language, Distance, Practicality, and Influence; each with three subcategories. It is activated through provoking key conversations to inform future community action.

text: A case study of Pipiri Ki A Papatūānuku This thesis is an examination and analysis of the environmental initiative Pipiri Ki A Papatūānuku, co-founded by Waimirirangi Ormsby (née Koopu-Stone) and myself, Tamoko Ormsby. The primary aim of this research was to achieve an understanding of the PKP initiative at the individual level and to inform future collective action at the community level. As such, my primary research question is:

How can Pipiri Ki A Papatūānuku inform community-scale action that contributes to our more-than-human relationship with Papatūānuku within our current capitalist settler-colonial context?

The study is part-autoethnographic in that it is informed by my personal reflections and experiences as a co-founder, operator, and participant of the initiative. In addition, the study explores the number of participants who signed up yearly for each action and employs a brief descriptive analysis of the initiative.

The literature review explores how common Western notions of environmentalism are devoid of the spiritual, cultural, and relational aspects present within indigenous and Māori knowledge systems. It touches on the histories of capitalism and colonialism and how these have led to the consumptogenic society we are in. It aims to illustrate the nexus between the Māori and Western Eurocentric worlds.

He Whatu is the framework that has emerged from this case study as the means to respond to the primary research question. The framework was developed by analyzing the key themes of PKP over the years 2017 to 2021. He Whatu has five key elements: Identity, Language, Distance, Practicality, and Influence; each with three subcategories. It is activated through provoking key conversations to inform future community action.

year: 2023