scholarly journals Impact and Management of Small Farm  Dams in Hawke's Bay, New Zealand

2021 ◽  
Author(s):  
◽  
Jan C. Thompson
Keyword(s):  
Water Quality ◽  
New Zealand ◽  
Agricultural Intensification ◽  
Regional Scale ◽  
Water Storage ◽  
Small Farm ◽  
Cumulative Impact ◽  
Small Dams ◽  
Regulated Stream ◽  
Paired Catchment

<p>In New Zealand, thousands of small dams have been built in agricultural areas for the purpose of providing water storage for stock and/or irrigation. These dams interrupt flow on perennial or intermittent streams; however, almost nothing is known of the downstream impact of these dams on flow regime, water quality, sediment transfer, and channel morphology. The cumulative impact of these dams at the catchment scale is likely to be significant. The present research was undertaken in the Ruataniwha Plains of Central Hawke's Bay. With further agricultural intensification in the region, it is expected that the construction of small farm dams will continue as farmers try to secure more on-farm water storage. This study attempts to quantify the effects of these storages in two parts: a paired catchment field study to determine the downstream effects of small dams, and a modelling study to investigate the cumulative impact of these storages on streamflow volumes at the regional scale. Results from the paired catchment field study suggest that the regulation of a small stream by three dams (total storage 11.6 ML) has lowered annual runoff volumes, decreased peak flows, increased periods of low flow, and lengthened the response time of the stream to storm events, as compared to the adjacent unregulated stream. Higher precipitation volumes in the winter act to reduce the degree of these impacts, although flow volumes are still lower as compared to the unregulated stream. Throughout the winter, ponds are full and connected to the downstream system, leading to more days of flow on the regulated stream. The regulation of flow has lowered stream erosion potentials, as evidenced by differences in channel bed sediment and morphological characteristics between the two streams. The regulated channel is aggradational, with no evidence of channel scour found over its length. Water quality changes are also observed, with lower water quality measured in the regulated stream and in the ponds, and generally higher water quality measured in the unregulated stream. The impact of farm dams on streamflow in two regional catchments was investigated using two off-the-shelf models (TEDI, Source Catchments). Model predictions suggest that the current volume of farm dam storage has decreased average annual flow volumes in the two catchments by approximately 1%. The predicted streamflow decrease is more significant under scenarios of future agricultural intensification. Regional climate change scenarios do not show a large effect on catchment streamflow volumes. In comparison to known catchment characteristics, the two models have limitations related to some of the model assumptions, and to the inability of the rainfall-runoff model to accurately represent seasonality of flow in the study catchments. On the whole, the models seem to be biased towards underestimating farm dam impact at the regional scale. The study concludes that farm dams have already influenced catchment streamflow and related processes to some degree. At present, the majority of small farm dams in New Zealand do not require resource consent from local council authorities for construction. It is reasonable to expect that farm dams will continue to be built, and it is important that further construction is undertaken with a sound knowledge of the cumulative impact these dams have on catchment processes and existing streamflow volumes. Proper management will mitigate some of these impacts. Management recommendations include the compilation of an inventory of small dams and their characteristics, continued field investigations, and refinement of a catchment model in order to provide a flexible platform for exploring further management options in the region. This study represents a critical first step towards integrated land and water management in the Ruataniwha Plains and will have relevance for the study and management of farm dams in other areas of New Zealand.</p>

scholarly journals Impact and Management of Small Farm  Dams in Hawke's Bay, New Zealand

2021 ◽  
Author(s):  
◽  
Jan C. Thompson
Keyword(s):  
Water Quality ◽  
New Zealand ◽  
Agricultural Intensification ◽  
Regional Scale ◽  
Water Storage ◽  
Small Farm ◽  
Cumulative Impact ◽  
Small Dams ◽  
Regulated Stream ◽  
Paired Catchment

<p>In New Zealand, thousands of small dams have been built in agricultural areas for the purpose of providing water storage for stock and/or irrigation. These dams interrupt flow on perennial or intermittent streams; however, almost nothing is known of the downstream impact of these dams on flow regime, water quality, sediment transfer, and channel morphology. The cumulative impact of these dams at the catchment scale is likely to be significant. The present research was undertaken in the Ruataniwha Plains of Central Hawke's Bay. With further agricultural intensification in the region, it is expected that the construction of small farm dams will continue as farmers try to secure more on-farm water storage. This study attempts to quantify the effects of these storages in two parts: a paired catchment field study to determine the downstream effects of small dams, and a modelling study to investigate the cumulative impact of these storages on streamflow volumes at the regional scale. Results from the paired catchment field study suggest that the regulation of a small stream by three dams (total storage 11.6 ML) has lowered annual runoff volumes, decreased peak flows, increased periods of low flow, and lengthened the response time of the stream to storm events, as compared to the adjacent unregulated stream. Higher precipitation volumes in the winter act to reduce the degree of these impacts, although flow volumes are still lower as compared to the unregulated stream. Throughout the winter, ponds are full and connected to the downstream system, leading to more days of flow on the regulated stream. The regulation of flow has lowered stream erosion potentials, as evidenced by differences in channel bed sediment and morphological characteristics between the two streams. The regulated channel is aggradational, with no evidence of channel scour found over its length. Water quality changes are also observed, with lower water quality measured in the regulated stream and in the ponds, and generally higher water quality measured in the unregulated stream. The impact of farm dams on streamflow in two regional catchments was investigated using two off-the-shelf models (TEDI, Source Catchments). Model predictions suggest that the current volume of farm dam storage has decreased average annual flow volumes in the two catchments by approximately 1%. The predicted streamflow decrease is more significant under scenarios of future agricultural intensification. Regional climate change scenarios do not show a large effect on catchment streamflow volumes. In comparison to known catchment characteristics, the two models have limitations related to some of the model assumptions, and to the inability of the rainfall-runoff model to accurately represent seasonality of flow in the study catchments. On the whole, the models seem to be biased towards underestimating farm dam impact at the regional scale. The study concludes that farm dams have already influenced catchment streamflow and related processes to some degree. At present, the majority of small farm dams in New Zealand do not require resource consent from local council authorities for construction. It is reasonable to expect that farm dams will continue to be built, and it is important that further construction is undertaken with a sound knowledge of the cumulative impact these dams have on catchment processes and existing streamflow volumes. Proper management will mitigate some of these impacts. Management recommendations include the compilation of an inventory of small dams and their characteristics, continued field investigations, and refinement of a catchment model in order to provide a flexible platform for exploring further management options in the region. This study represents a critical first step towards integrated land and water management in the Ruataniwha Plains and will have relevance for the study and management of farm dams in other areas of New Zealand.</p>

scholarly journals A paleolimnological investigation of agricultural intensification, water quality and ecosystem change at Lake Nganoke, southern Wairarapa, NZ

2021 ◽  
Author(s):  
◽  
Jakob Parrish
Keyword(s):  
Water Quality ◽  
New Zealand ◽  
Agricultural Intensification ◽  
Ecosystem Change ◽  
Lake Ecosystem ◽  
Nutrient Fluxes ◽  
Paleoenvironmental Reconstruction ◽  
The Past ◽  
Algal Productivity ◽  
Stocking Rates

<p>Decreasing water quality of lakes as a result of anthropogenic landuse and specifically agricultural intensification is well documented in New Zealand. However, monitoring records of lake health are typically short, only commencing once signs of lake deterioration are observed. The shortness of the instrumental record precludes a detailed understanding of the relationship between landuse change, lake ecosystem trajectories and the effectiveness of mitigation strategies such as riparian planting. Paleolimnological reconstruction from sediment cores has the potential to develop high-resolution time series that may extend lake monitoring centuries into the past. This thesis uses paleoenvironmental reconstruction to investigate lake ecosystem change and water quality in Lake Nganoke, Wairarapa, New Zealand as a result of landuse intensification. The primary aim of this thesis is to reconstruct the past environment of Lake Nganoke from a pre-human reference state to the current day to assess: 1) how increased nutrient fluxes associated with landuse intensification have impacted the lake ecosystem; and 2) the ability of riparian zones to buffer these fluxes. The reconstruction was achieved using a multi proxy approach with pre and post-human environments of Lake Nganoke characterised using Palynology, geochemistry, eDNA and hyperspectral scanning.  Māori land clearance was identified at ~AD 1450 (95% CI: AD 1417-1551). The appearance of Pinus pollen and increases in fertilisation and stocking rates placed European arrival at ~AD 1850 (95% CI: 1809 - 1870), while intensification of agricultural landuse occurred post ~AD 1950 (95% CI: 1948 - 1964). The prehuman environment of Lake Nganoke experienced little change, with the catchment dominated by tall trees and likely heavily forested. The lake ecosystem and water quality during this time showed little to no change, with algal productivity likely driven by a constant input of natural nutrients. Post Māori arrival, algal productivity was reduced suggesting an increase in water quality likely driven by added lake marginal plants providing a riparian buffer to terrestrially derived nutrients. Lake productivity increased dramatically post European arrival ~AD 1850, coeval with an increase in sediment Cd, suggesting that fertilisation may have driven a decline in water quality. Further increases in fertilisation and stocking rates indicate additional agricultural nutrient fluxes entering Lake Nganoke in AD 1950 when agriculture intensified. Abundances in denitrifying Gammaproteobacteria indicate increases in nutrient loading while bloom forming Cyanobacteria peak ~AD 2000 before declining till present. Riparian planting following Māori arrival appears sufficient to buffer the lake against increased terrestrial nutrient fluxes associated with land clearing. However, a riparian zone that covers the majority of the catchment post European settlement was inadequate in altering the lake’s degrading ecosystem and water quality trajectory.</p>

scholarly journals A paleolimnological investigation of agricultural intensification, water quality and ecosystem change at Lake Nganoke, southern Wairarapa, NZ

2021 ◽  
Author(s):  
◽  
Jakob Parrish
Keyword(s):  
Water Quality ◽  
New Zealand ◽  
Agricultural Intensification ◽  
Ecosystem Change ◽  
Lake Ecosystem ◽  
Nutrient Fluxes ◽  
Paleoenvironmental Reconstruction ◽  
The Past ◽  
Algal Productivity ◽  
Stocking Rates

<p>Decreasing water quality of lakes as a result of anthropogenic landuse and specifically agricultural intensification is well documented in New Zealand. However, monitoring records of lake health are typically short, only commencing once signs of lake deterioration are observed. The shortness of the instrumental record precludes a detailed understanding of the relationship between landuse change, lake ecosystem trajectories and the effectiveness of mitigation strategies such as riparian planting. Paleolimnological reconstruction from sediment cores has the potential to develop high-resolution time series that may extend lake monitoring centuries into the past. This thesis uses paleoenvironmental reconstruction to investigate lake ecosystem change and water quality in Lake Nganoke, Wairarapa, New Zealand as a result of landuse intensification. The primary aim of this thesis is to reconstruct the past environment of Lake Nganoke from a pre-human reference state to the current day to assess: 1) how increased nutrient fluxes associated with landuse intensification have impacted the lake ecosystem; and 2) the ability of riparian zones to buffer these fluxes. The reconstruction was achieved using a multi proxy approach with pre and post-human environments of Lake Nganoke characterised using Palynology, geochemistry, eDNA and hyperspectral scanning.  Māori land clearance was identified at ~AD 1450 (95% CI: AD 1417-1551). The appearance of Pinus pollen and increases in fertilisation and stocking rates placed European arrival at ~AD 1850 (95% CI: 1809 - 1870), while intensification of agricultural landuse occurred post ~AD 1950 (95% CI: 1948 - 1964). The prehuman environment of Lake Nganoke experienced little change, with the catchment dominated by tall trees and likely heavily forested. The lake ecosystem and water quality during this time showed little to no change, with algal productivity likely driven by a constant input of natural nutrients. Post Māori arrival, algal productivity was reduced suggesting an increase in water quality likely driven by added lake marginal plants providing a riparian buffer to terrestrially derived nutrients. Lake productivity increased dramatically post European arrival ~AD 1850, coeval with an increase in sediment Cd, suggesting that fertilisation may have driven a decline in water quality. Further increases in fertilisation and stocking rates indicate additional agricultural nutrient fluxes entering Lake Nganoke in AD 1950 when agriculture intensified. Abundances in denitrifying Gammaproteobacteria indicate increases in nutrient loading while bloom forming Cyanobacteria peak ~AD 2000 before declining till present. Riparian planting following Māori arrival appears sufficient to buffer the lake against increased terrestrial nutrient fluxes associated with land clearing. However, a riparian zone that covers the majority of the catchment post European settlement was inadequate in altering the lake’s degrading ecosystem and water quality trajectory.</p>

Enterococci in the New Zealand environment: implications for water quality monitoring

1997 ◽  
Vol 35 (11-12) ◽  
pp. 325-331 ◽  
Author(s):  
S. A. Anderson ◽  
S. J. Turner ◽  
G. D. Lewis
Keyword(s):  
Water Quality ◽  
New Zealand ◽  
Water Quality Monitoring ◽  
Epidemiological Studies ◽  
High Ratio ◽  
Quality Data ◽  
Considerable Proportion ◽  
Multiple Sources ◽  
Water Quality Data ◽  
Bathing Water Quality

Faecal enterococci ecology outside the host is of great relevance when using these organisms as indicators of water quality. As a complement to New Zealand epidemiological studies of bathing water quality and health risk, a study of the environmental occurrence of these organisms has been undertaken. Specific concerns over the use of enterococci derive from the unique situation in New Zealand which has few chlorinated sewage effluents, a high ratio of grazing animals to humans, and significant inputs of animal processing effluents into the environment. Human and animal faecal wastes are the main sources, with 106–107cfu/100ml found in human sewage. Analysis of domestic and feral animal faeces found enterococci in the range of 101–106cfu/g with considerable variation between species. The latter observations support the notion that a considerable proportion of the load in urban/rural catchments and waterways (typically 102–103 enterococci cfu/100ml) is derived from non-human sources. Previous studies of enterococci quiescence in marine/fresh waters indicate that they enter a non-growth phase, exposure to sunlight markedly reducing culturability on selective and non-selective media. Enterococci were also found to survive/multiply within specific non-faecal environments. Enterococci on degrading drift seaweed at recreational beaches exceeded seawater levels by 2–4 orders of magnitude, suggesting that expansion had occurred in this permissive environment with resultant potential to contaminate adjacent sand and water. These studies suggest that multiple sources, environmental persistence, and environmental expansion of enterococci within selected niches add considerable complexity to the interpretation of water quality data.

scholarly journals The effect of household storage tanks/vessels and user practices on the quality of water: a systematic review of literature

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Musa Manga ◽  
Timothy G. Ngobi ◽  
Lawrence Okeny ◽  
Pamela Acheng ◽  
Hidaya Namakula ◽  
...  
Keyword(s):  
Systematic Review ◽  
Water Quality ◽  
Storage Tank ◽  
Grey Literature ◽  
Water Storage ◽  
Storage Tanks ◽  
Water Storage Tank ◽  
Hygiene Practices ◽  
Quality Of Water ◽  
Vessel Material

Abstract Background Household water storage remains a necessity in many communities worldwide, especially in the developing countries. Water storage often using tanks/vessels is envisaged to be a source of water contamination, along with related user practices. Several studies have investigated this phenomenon, albeit in isolation. This study aimed at developing a systematic review, focusing on the impacts of water storage tank/vessel features and user practices on water quality. Methods Database searches for relevant peer-reviewed papers and grey literature were done. A systematic criterion was set for the selection of publications and after scrutinizing 1106 records, 24 were selected. These were further subjected to a quality appraisal, and data was extracted from them to complete the review. Results and discussion Microbiological and physicochemical parameters were the basis for measuring water quality in storage tanks or vessels. Water storage tank/vessel material and retention time had the highest effect on stored water quality along with age, colour, design, and location. Water storage tank/vessel cleaning and hygiene practices like tank/vessel covering were the user practices most investigated by researchers in the literature reviewed and they were seen to have an impact on stored water quality. Conclusions There is evidence in the literature that storage tanks/vessels, and user practices affect water quality. Little is known about the optimal tank/vessel cleaning frequency to ensure safe drinking water quality. More research is required to conclusively determine the best matrix of tank/vessel features and user practices to ensure good water quality.

Cumulative impact of marinas on estuarine water quality

1996 ◽  
Vol 20 (3) ◽  
pp. 385-396 ◽  
Author(s):  
T. L. McAllister ◽  
M. F. Overton ◽  
E. D. Brill
Keyword(s):  
Water Quality ◽  
Estuarine Water ◽  
Cumulative Impact ◽  
Estuarine Water Quality

scholarly journals Climate impact on the development of Pre-Classic Maya civilisation

2018 ◽  
Vol 14 (8) ◽  
pp. 1253-1273 ◽  
Author(s):  
Kees Nooren ◽  
Wim Z. Hoek ◽  
Brian J. Dermody ◽  
Didier Galop ◽  
Sarah Metcalfe ◽  
...  
Keyword(s):  
North Atlantic ◽  
Agricultural Intensification ◽  
Climatic Variability ◽  
Regional Scale ◽  
Climate Impact ◽  
Classic Period ◽  
Beach Ridge ◽  
Maya Lowlands ◽  
The North ◽  
The Impact

Abstract. The impact of climate change on the development and disintegration of Maya civilisation has long been debated. The lack of agreement among existing palaeoclimatic records from the region has prevented a detailed understanding of regional-scale climatic variability, its climatic forcing mechanisms and its impact on the ancient Maya. We present two new palaeo-precipitation records for the central Maya lowlands, spanning the Pre-Classic period (1800 BCE–250 CE), a key epoch in the development of Maya civilisation. A beach ridge elevation record from world's largest late Holocene beach ridge plain provides a regional picture, while Lake Tuspan's diatom record is indicative of precipitation changes at a local scale. We identify centennial-scale variability in palaeo-precipitation that significantly correlates with the North Atlantic δ14C atmospheric record, with a comparable periodicity of approximately 500 years, indicating an important role of North Atlantic atmospheric–oceanic forcing on precipitation in the central Maya lowlands. Our results show that the Early Pre-Classic period was characterised by relatively dry conditions, shifting to wetter conditions during the Middle Pre-Classic period, around the well-known 850 BCE (2.8 ka) event. We propose that this wet period may have been unfavourable for agricultural intensification in the central Maya lowlands, explaining the relatively delayed development of Maya civilisation in this area. A return to relatively drier conditions during the Late Pre-Classic period coincides with rapid agricultural intensification in the region and the establishment of major cities.

scholarly journals Calibration and evaluation of a semi-distributed watershed model of Sub-Saharan Africa using GRACE data

2012 ◽  
Vol 16 (9) ◽  
pp. 3083-3099 ◽  
Author(s):  
H. Xie ◽  
L. Longuevergne ◽  
C. Ringler ◽  
B. R. Scanlon
Keyword(s):  
Regional Scale ◽  
Water Storage ◽  
Hydrologic Model ◽  
Sub Saharan Africa ◽  
Model Parameters ◽  
Total Water ◽  
Discharge Data ◽  
Model Based ◽  
Grace Data ◽  
Sub Saharan

Abstract. Irrigation development is rapidly expanding in mostly rainfed Sub-Saharan Africa. This expansion underscores the need for a more comprehensive understanding of water resources beyond surface water. Gravity Recovery and Climate Experiment (GRACE) satellites provide valuable information on spatio-temporal variability in water storage. The objective of this study was to calibrate and evaluate a semi-distributed regional-scale hydrologic model based on the Soil and Water Assessment Tool (SWAT) code for basins in Sub-Saharan Africa using seven-year (July 2002–April 2009) 10-day GRACE data and multi-site river discharge data. The analysis was conducted in a multi-criteria framework. In spite of the uncertainty arising from the tradeoff in optimising model parameters with respect to two non-commensurable criteria defined for two fluxes, SWAT was found to perform well in simulating total water storage variability in most areas of Sub-Saharan Africa, which have semi-arid and sub-humid climates, and that among various water storages represented in SWAT, water storage variations in soil, vadose zone and groundwater are dominant. The study also showed that the simulated total water storage variations tend to have less agreement with GRACE data in arid and equatorial humid regions, and model-based partitioning of total water storage variations into different water storage compartments may be highly uncertain. Thus, future work will be needed for model enhancement in these areas with inferior model fit and for uncertainty reduction in component-wise estimation of water storage variations.

scholarly journals Application of global models and satellite data for smaller-scale groundwater recharge studies

2016 ◽  
Author(s):  
Rogier Westerhoff ◽  
Paul White ◽  
Zara Rawlinson
Keyword(s):  
New Zealand ◽  
Satellite Data ◽  
Input Data ◽  
Large Scale ◽  
Regional Scale ◽  
Global Scale ◽  
Global Models ◽  
Scale Models ◽  
Boundary Issues ◽  
Rainfall Recharge

Abstract. Large-scale models and satellite data are increasingly used to characterise groundwater and its recharge at the global scale. Although these models have the potential to fill in data gaps and solve trans-boundary issues, they are often neglected in smaller-scale studies, since data are often coarse or uncertain. Large-scale models and satellite data could play a more important role in smaller-scale (i.e., national or regional) studies, if they could be adjusted to fit that scale. In New Zealand, large-scale models and satellite data are not used for groundwater recharge estimation at the national scale, since regional councils (i.e., the water managers) have varying water policy and models are calibrated at the local scale. Also, some regions have many localised ground observations (but poor record coverage), whereas others are data-sparse. Therefore, estimation of recharge is inconsistent at the national scale. This paper presents an approach to apply large-scale, global, models and satellite data to estimate rainfall recharge at the national to regional scale across New Zealand. We present a model, NGRM, that is largely inspired by the global-scale WaterGAP recharge model, but is improved and adjusted using national data. The NGRM model uses MODIS-derived ET and vegetation satellite data, and the available nation-wide datasets on rainfall, elevation, soil and geology. A valuable addition to the recharge estimation is the model uncertainty estimate, based on variance, covariance and sensitivity of all input data components in the model environment. This research shows that, with minor model adjustments and use of improved input data, large-scale models and satellite data can be used to derive rainfall recharge estimates, including their uncertainty, at the smaller scale, i.e., national and regional scale of New Zealand. The estimated New Zealand recharge of the NGRM model compare well to most local and regional lysimeter data and recharge models. The NGRM is therefore assumed to be capable to fill in gaps in data-sparse areas and to create more consistency between datasets from different regions, i.e., to solve trans-boundary issues. This research also shows that smaller-scale recharge studies in New Zealand should include larger boundaries than only a (sub-)aquifer, and preferably the whole catchment. This research points out the need for improved collaboration on the international to national to regional levels to further merge large-scale (global) models to smaller (i.e., national or regional) scales. Future research topics should, collaboratively, focus on: improvement of rainfall-runoff and snowmelt methods; inclusion of river recharge; further improvement of input data (rainfall, evapotranspiration, soil and geology); and the impact of recharge uncertainty in mountainous and irrigated areas.

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