title: Influence of Vegetation Cover on Coastal Aquifer Fluctuation and Sand Transport on Matakana Island

authors: Muller, Joshua Alois

subjects: Coastal

abstract: The Bay of Plenty beaches on the east coast of the North Island, New Zealand are of significant physical, ecological and economic importance. Over the previous century, anthropogenic development and the introduction of non-indigenous coastal plant species has lead to a degradation of many of the Bay of Plenty regions’ coastal dune environments. Restoring these sections of coastline to their natural state strengthens the barrier they provide between coastal developments and the coastal ocean, whilst also promoting the growth of native plant species and improving habitat for local macro-invertebrate species. The influence of vegetation on aquifer levels and aeolian sediment transport in the dune and foredune was investigated at Matakana Island in the Western Bay of Plenty. Monitoring of the water table between March and November 2010 was undertaken at two adjacent sample sites, with different dominant overlying vegetation, Ammophila arenaria and Spinifex sericeus. During this time, aeolian sediment transport rates were also monitored through the deployment of sediment traps and two small climate stations. Results showed that aquifer levels beneath the dune face were highly variable. Fluctuations occurred at a range of time scales, stemming from variations in tide, rainfall and profile shape. Short-term fluctuation was primarily linked to tidal forcing. Tidal fluctuations were observed in the aquifer, and differed from tidal fluctuations directly offshore in their shape and amplitude, with some lag between tide and aquifer fluctuations also evident. Aquifer fluctuation shape and lag, and differences between sample sites were linked to the beach drainage capability through aquifer porosity and permeability; hydraulic conductivity; and transmissivity. Long-term change in beach profile shape further influenced aquifer levels, with an accreting beach resulting in an elevating average aquifer level and an eroding beach resulting in a diminishing aquifer level. Aeolian sediment deposition varied greatly across the cross-shore profile. Transport rates were limited by a small beach width when high tides combined with storm surge and wave run-ups limiting the source area. Rainfall further reduced transport potential when coinciding with high wind speed events. Sediment deposition was evenly distributed in the Spinifex dominated dune system, whilst deposition in the Ammophila dune primarily occurred at the seaward limit of vegetation growth. This pattern of deposition is linked to the characteristics of each species, primarily their average height and growth density. Sediment deposition differences between sites explain variances in sediment compaction which alters dune porosity and permeability at each site. Greater porosity and permeability in the Spinifex dominated dune saw the aquifer draining more readily. Lower beach aquifer levels aid accretion and greaten the source for onshore aeolian sediment transport. Spinifex dominated dunes are therefore suggested to provide healthier beach states on Bay of Plenty beaches.

text: Influence of Vegetation Cover on Coastal Aquifer Fluctuation and Sand Transport on Matakana Island The Bay of Plenty beaches on the east coast of the North Island, New Zealand are of significant physical, ecological and economic importance. Over the previous century, anthropogenic development and the introduction of non-indigenous coastal plant species has lead to a degradation of many of the Bay of Plenty regions’ coastal dune environments. Restoring these sections of coastline to their natural state strengthens the barrier they provide between coastal developments and the coastal ocean, whilst also promoting the growth of native plant species and improving habitat for local macro-invertebrate species. The influence of vegetation on aquifer levels and aeolian sediment transport in the dune and foredune was investigated at Matakana Island in the Western Bay of Plenty. Monitoring of the water table between March and November 2010 was undertaken at two adjacent sample sites, with different dominant overlying vegetation, Ammophila arenaria and Spinifex sericeus. During this time, aeolian sediment transport rates were also monitored through the deployment of sediment traps and two small climate stations. Results showed that aquifer levels beneath the dune face were highly variable. Fluctuations occurred at a range of time scales, stemming from variations in tide, rainfall and profile shape. Short-term fluctuation was primarily linked to tidal forcing. Tidal fluctuations were observed in the aquifer, and differed from tidal fluctuations directly offshore in their shape and amplitude, with some lag between tide and aquifer fluctuations also evident. Aquifer fluctuation shape and lag, and differences between sample sites were linked to the beach drainage capability through aquifer porosity and permeability; hydraulic conductivity; and transmissivity. Long-term change in beach profile shape further influenced aquifer levels, with an accreting beach resulting in an elevating average aquifer level and an eroding beach resulting in a diminishing aquifer level. Aeolian sediment deposition varied greatly across the cross-shore profile. Transport rates were limited by a small beach width when high tides combined with storm surge and wave run-ups limiting the source area. Rainfall further reduced transport potential when coinciding with high wind speed events. Sediment deposition was evenly distributed in the Spinifex dominated dune system, whilst deposition in the Ammophila dune primarily occurred at the seaward limit of vegetation growth. This pattern of deposition is linked to the characteristics of each species, primarily their average height and growth density. Sediment deposition differences between sites explain variances in sediment compaction which alters dune porosity and permeability at each site. Greater porosity and permeability in the Spinifex dominated dune saw the aquifer draining more readily. Lower beach aquifer levels aid accretion and greaten the source for onshore aeolian sediment transport. Spinifex dominated dunes are therefore suggested to provide healthier beach states on Bay of Plenty beaches.

year: 2011

title: The economic impact of climate change on wheat and maize yields in the North China Plain.

authors: Song, Chunxiao

subjects: climate change

abstract: Climate change has significantly affected agricultural production. As one of China's most important agricultural production regions, the North China Plain (NCP) is subject to climate change. This paper examines the influence of climate change on the wheat and maize yields at household and village levels, using the multilevel model based on a large panel survey dataset in the NCP. The results show that: (i) Extreme weather events (drought and flood) would significantly reduce the wheat and maize yields. So, the governments should establish and improve the emergency service system of disaster warning and encourage farmers to mitigate the adverse effects of disasters. (ii) Over the past three decades, the NCP has experienced climate change that affects its grain production. Therefore, it is imperative to build the farmers' adaptive capacity to climate change. (iii) Spatial variations in crop yield are significantly influenced by the household characteristics and the heterogeneity of village economic conditions. Therefore, in addition to promoting household production, it is necessary to strengthen and promote China's development of the rural collective economy, especially the construction of rural irrigation and drainage infrastructures.

text: The economic impact of climate change on wheat and maize yields in the North China Plain. Climate change has significantly affected agricultural production. As one of China's most important agricultural production regions, the North China Plain (NCP) is subject to climate change. This paper examines the influence of climate change on the wheat and maize yields at household and village levels, using the multilevel model based on a large panel survey dataset in the NCP. The results show that: (i) Extreme weather events (drought and flood) would significantly reduce the wheat and maize yields. So, the governments should establish and improve the emergency service system of disaster warning and encourage farmers to mitigate the adverse effects of disasters. (ii) Over the past three decades, the NCP has experienced climate change that affects its grain production. Therefore, it is imperative to build the farmers' adaptive capacity to climate change. (iii) Spatial variations in crop yield are significantly influenced by the household characteristics and the heterogeneity of village economic conditions. Therefore, in addition to promoting household production, it is necessary to strengthen and promote China's development of the rural collective economy, especially the construction of rural irrigation and drainage infrastructures.

year: 2022-05-07

title: Katoa: A descriptive, comparative and historical analysis

authors: Wessels, Kanauhea Janion

subjects: discontinuous quantification

abstract: Katoa, approximately translated as ‘all, every’, functions as the universal quantifier in te reo Māori (the Māori language), inherited from Proto Polynesian *katoa. Less well known is its occurrence as a postnominal modifier in singular noun phrases, contributing the meaning of ‘whole’, and as a nominal head meaning ‘all (of them), the whole (of it)’. As a postverbal modifier, katoa can quantify a subject noun phrase with the same meanings of ‘all, every’ and ‘whole’, and it can modify situations expressed by the verb, meaning ‘wholly, completely’. In this paper, we examine the behaviour of katoa in te reo Māori, comparing some properties of katoa with the behaviour of quantifiers in related Polynesian languages. This, in turn, informs our understanding of the prehistory of quantification in Polynesian, where we observe evidence of both retention and replacement of quantifier forms.

text: Katoa: A descriptive, comparative and historical analysis Katoa, approximately translated as ‘all, every’, functions as the universal quantifier in te reo Māori (the Māori language), inherited from Proto Polynesian *katoa. Less well known is its occurrence as a postnominal modifier in singular noun phrases, contributing the meaning of ‘whole’, and as a nominal head meaning ‘all (of them), the whole (of it)’. As a postverbal modifier, katoa can quantify a subject noun phrase with the same meanings of ‘all, every’ and ‘whole’, and it can modify situations expressed by the verb, meaning ‘wholly, completely’. In this paper, we examine the behaviour of katoa in te reo Māori, comparing some properties of katoa with the behaviour of quantifiers in related Polynesian languages. This, in turn, informs our understanding of the prehistory of quantification in Polynesian, where we observe evidence of both retention and replacement of quantifier forms.

year: 2024