An analysis of historical data and a detailed field survey were used to define the pattern and efficiency of water use in the Valetta Irrigation Scheme in Canterbury, New Zealand. In this scheme of 7050 ha, pasture is irrigated using... more
An analysis of historical data and a detailed field survey were used to define the pattern and efficiency of water use in the Valetta Irrigation Scheme in Canterbury, New Zealand. In this scheme of 7050 ha, pasture is irrigated using river water, distributed in unlined open channels, and applied by flooding border strips. Statistical analysis of historical water use and climatic data shows that the response of the scheme water use to climatic factors, particularly rainfall, is constrained by the limited channel capacities and delivery schedule in the scheme. Up to 80% of water diverted from the river was delivered to the farms during the 1979–80 irrigation season. Average on-farm water use is 200 mm per application, corresponding to an on-farm use efficiency of 26%. Seasonal water use averages 1171 mm (1979–80 — 1982–83), whereas nearby farms using spray irrigation use, on average, 74 mm of water per application and 160 mm per season. The greatest potential for water savings on this scheme lies with more efficient application of water on-farm, although some savings would be obtained by lining off-farm distribution channels.
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... Citation: Yang, Y., M. Uddstrom, and M. Duncan (2011), Effects of short spin‐up periods on soil moisture simulation and the causes over New ... 2. Description of Model and Experiments [5] The LSM used in this paper is JULES (the Joint... more
... Citation: Yang, Y., M. Uddstrom, and M. Duncan (2011), Effects of short spin‐up periods on soil moisture simulation and the causes over New ... 2. Description of Model and Experiments [5] The LSM used in this paper is JULES (the Joint UK Land Environment Simulator [Best et al ...
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The occurrence of hydrological and agricultural droughts in a river-based irrigation scheme in New Zealand was investigated in this study. Hydrological drought occurred when irrigation supplies fell short of demands. Agricultural drought... more
The occurrence of hydrological and agricultural droughts in a river-based irrigation scheme in New Zealand was investigated in this study. Hydrological drought occurred when irrigation supplies fell short of demands. Agricultural drought was defined by a soil moisture deficit arising from imbalances in rainfall and evapotranspiration during the irrigation season (September–April). Hydrological drought was further characterized by the number of days supplies fully or partially fell short of demands (duration) and the percentage of irrigation abstractions available when demands were partially met (severity). Based on 37 years (1972–2008) of observed river flow data (supply), it was found that one-fourth of hydrological droughts occurred early (September–December) during irrigation season. Hydrological drought started to intensify, both in duration and severity, from January and peaked in March. On the basis of climate data from 1972 to 2008, the monthly soil moisture deficit (difference between rainfall and...
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... level. Page 6. 232 Smart et al. -400 -300 -200 -100 0 100 200 300 -300 -200 -100 0 100 200 300 -400 -300 -200 -100 0 100 100 200 300 400 500 Figure 3 Visualization of the DEMs produced by laser scanning of surfaces showing gravel at... more
... level. Page 6. 232 Smart et al. -400 -300 -200 -100 0 100 200 300 -300 -200 -100 0 100 200 300 -400 -300 -200 -100 0 100 100 200 300 400 500 Figure 3 Visualization of the DEMs produced by laser scanning of surfaces showing gravel at the Waimakariri A site (left) and water-...
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Relatively Rough Flow Resistance Equations. [Journal of Hydraulic Engineering 128, 568 (2002)]. Graeme M. Smart, Maurice J. Duncan, Jeremy M. Walsh. Abstract. ... is akin to the hydraulic depth used by US Army Corps of Engineers in... more
Relatively Rough Flow Resistance Equations. [Journal of Hydraulic Engineering 128, 568 (2002)]. Graeme M. Smart, Maurice J. Duncan, Jeremy M. Walsh. Abstract. ... is akin to the hydraulic depth used by US Army Corps of Engineers in navigation channels. ...
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It has long been recognized that soil moisture has a key role in controlling evapo- transpiration during dryer periods, as well as runoff processes, particularly saturation excess runoff. The temporal and spatial variability of moisture... more
It has long been recognized that soil moisture has a key role in controlling evapo- transpiration during dryer periods, as well as runoff processes, particularly saturation excess runoff. The temporal and spatial variability of moisture can be an important influence on the temporal and spatial characteristics of these processes. More recently, the role of soil moisture in controlling lateral flow processes has re- ceived close attention, with switching between persistent dry and wet states leading to switches between controls on spatial patterns of soil moisture and consequent changes in runoff behaviour. In this paper we will review results on the spatial and temporal variability of soil moisture at the small catchment scale, concentrating in particular on dominant controls and temporal changes in dominant controls. We will discuss the climatic and catchment characteristics under which switching between dominant controls is likely. We will also present results relating spatial soil moisture behaviour to soil moisture state and relating rainfall-runoff response to moisture state: in particular we investi- gated the relationships between the basin soil moisture dynamic and the occurrence of very extreme flood events. The spatial probability density function of soil moisture is bounded by wilting point and porosity. This bounding combined with catchment processes leads to a strong link between spatial variance and spatial mean soil mois- ture, with an initial increase in variance followed by a decrease as mean soil moisture increases from wilting point to saturation. Changes in the spatial control of soil mois- ture and the relationship between soil moisture and terrain also occur as the spatial controls on the soil moisture pattern change in response to mean soil moisture. Strong links between the changes in the spatial characteristics of soil moisture will be demon- strated and the potential of measurements of soil moisture to provide information on catchment state and rainfall-runoff response will be explored.
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A study (2004–11) of a dairy catchment stream entering an oligotrophic lake in an area of very high rainfall (~5 m year–1) yielded median concentrations of total nitrogen (TN), total phosphorus (TP), suspended sediment (SS) and... more
A study (2004–11) of a dairy catchment stream entering an oligotrophic lake in an area of very high rainfall (~5 m year–1) yielded median concentrations of total nitrogen (TN), total phosphorus (TP), suspended sediment (SS) and Escherichia coli (E. coli) of 0.584, 0.074 and 3.7 g m–3, and 405/100 mL (most probable number method), respectively. Trend analysis indicated significant (P < 0.01) decreases for TN (–0.08 ± 0.02 g m–3 year–1), TP (–0.01 ± 0.005 g m–3 year–1) and SS (–0.45 ± 0.14 g m–3 year–1) and were partly attributable to improved exclusion of cattle from the stream. Water balance calculations indicated that approximately one-half the rainfall left as deep drainage that by-passed catchment outlet flow recorders. Estimates of catchment yields for TN were improved by taking into account groundwater hydrology and concentrations from well samples. Storm-flow monitoring inflows exceeding the 97.5th percentile contributed ~40% of total loads leaving the catchment so that spe...
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Soil moisture is a critical variable in many areas of hydrologic modelling yet measurements have not traditionally been a source of data for Hydrologists. While it has always been possible to measure soil moisture spatially and... more
Soil moisture is a critical variable in many areas of hydrologic modelling yet measurements have not traditionally been a source of data for Hydrologists. While it has always been possible to measure soil moisture spatially and temporally, the time and resources ...
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Water is critical for New Zealand’s primary industries. Our ability to achieve export earnings from our land hinges on the relative abundance of water we have and on our ability to anticipate and control its availability. However, as the... more
Water is critical for New Zealand’s primary industries. Our ability to achieve export earnings from our land hinges on the relative abundance of water we have and on our ability to anticipate and control its availability. However, as the climate changes in the coming decades and century, the water resources on which the primary industries depend, will most probably also change. Water resources vary naturally because of climate variability, such as the El Niño Southern Oscillation. Many water users in New Zealand are already well adapted to this variability. Anthropogenic climate change is anticipated to provide further changes in water resources, in addition to those that are familiar to water users. While no effect of anthropogenic climate change has yet been detected in New Zealand’s water cycle and resources, existing evidence internationally – and the mounting results from local modelling studies – indicate that effects are likely to begin within several decades’ time. These eff...
May 2007 for the presence of the non-indigenous freshwater diatom Didymosphenia geminata in high risk sites
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LiDAR–based DEMs are almost essential when it comes to high resolution floodplain modelling. Conventional LiDAR does not penetrate water bodies and additional bathymetric measurements are necessary to complete any parts of a DEM which... more
LiDAR–based DEMs are almost essential when it comes to high resolution floodplain modelling. Conventional LiDAR does not penetrate water bodies and additional bathymetric measurements are necessary to complete any parts of a DEM which were under water at the time of the LiDAR sortie. Bathymetric data collection is time-consuming, expensive and it requires careful processing to correctly interpolate between sounded points or cross-sections and to seamlessly integrate bathymetric data into a LiDAR-based DEM. Consequently, accuracy of underwater portions of a DEM is usually inferior to that of dry areas. When areas that are underwater at LiDAR collection time represent only a small portion of a flood domain, modelers often estimate a representative depth for these areas. By using LiDAR returns from the surface of flowing water, we investigate calculations to predict the level of the underlying river bed using a hydraulic model. To do this, there must be sufficient LiDAR returns from th...
Contemporary (event to decadal-scale) morphological changes in two large braided rivers in Canterbury, New Zealand, are described, along with laboratory studies that support the field observations. In the process, some new developments in... more
Contemporary (event to decadal-scale) morphological changes in two large braided rivers in Canterbury, New Zealand, are described, along with laboratory studies that support the field observations. In the process, some new developments in field and laboratory methods for investigating morphological change in braided rivers are presented, and Paola&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#x27;s (2001) hypothesis that braiding tendency should be influenced by a river&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#x27;s ability
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Experimental Design and Initial Results From the Mahurangi River Variability Experiment: MARVEX Ross Woods&#x27;, Rodger Grayson2, Andrew Western2, Maurice Duncan&#x27;, David Wilson2, Rodger Young2, Richard Ibbitt&#x27;,... more
Experimental Design and Initial Results From the Mahurangi River Variability Experiment: MARVEX Ross Woods&#x27;, Rodger Grayson2, Andrew Western2, Maurice Duncan&#x27;, David Wilson2, Rodger Young2, Richard Ibbitt&#x27;, Roddy Henderson&#x27;, Tom McMahon2 Spatial variability is at the ...
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Campbell Scientific CS615 instruments for soil moisture measurement have been installed in surface and sub-soils at 18 locations at one field site in New Zealand and at 7 locations at two field sites in Australia. Spatial patterns of soil... more
Campbell Scientific CS615 instruments for soil moisture measurement have been installed in surface and sub-soils at 18 locations at one field site in New Zealand and at 7 locations at two field sites in Australia. Spatial patterns of soil moisture have also been ...
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... study was to determine the change in WUA with re-duced flows for fish species rearing ... The maj or existing developments on the Raka-ia River consist of hydroelectric power stations at ... s to irrigate approximately 30,000 hectares... more
... study was to determine the change in WUA with re-duced flows for fish species rearing ... The maj or existing developments on the Raka-ia River consist of hydroelectric power stations at ... s to irrigate approximately 30,000 hectares south of the river, and the Central Plains scheme ...
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Page 1. JN Am. Benthol. Soc., 1999, 18(2):222-241 ? 1999 by The North American Benthological Society Velocity and sediment disturbance of periphyton in headwater streams: biomass and metabolism BARRY J. E BIGGS1 ...
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Page 1. JN Am. Benthol. Soc., 1999, 18(4):445-456 ? 1999 by The North American Benthological Socety Assessment of streambed stability in steep, bouldery streams: development of a new analytical technique MAURICE J ...
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The occurrence of hydrological and agricultural droughts in a river-based irrigation scheme in New Zealand was investigated in this study. Hydrological drought occurred when irrigation supplies fell short of demands. Agricultural drought... more
The occurrence of hydrological and agricultural droughts in a river-based irrigation scheme in New Zealand was investigated in this study. Hydrological drought occurred when irrigation supplies fell short of demands. Agricultural drought was defined by a soil moisture deficit arising from imbalances in rainfall and evapotranspiration during the irrigation season (September–April). Hydrological drought was further characterized by the number of days supplies fully or partially fell short of demands (duration) and the percentage of irrigation abstractions available when demands were partially met (severity). Based on 37 years (1972–2008) of observed river flow data (supply), it was found that one-fourth of hydrological droughts occurred early (September–December) during irrigation season. Hydrological drought started to intensify, both in duration and severity, from January and peaked in March. On the basis of climate data from 1972 to 2008, the monthly soil moisture deficit (difference between rainfall and...
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... Citation: Yang, Y., M. Uddstrom, and M. Duncan (2011), Effects of short spin‐up periods on soil moisture simulation and the causes over New ... 2. Description of Model and Experiments [5] The LSM used in this paper is JULES (the Joint... more
... Citation: Yang, Y., M. Uddstrom, and M. Duncan (2011), Effects of short spin‐up periods on soil moisture simulation and the causes over New ... 2. Description of Model and Experiments [5] The LSM used in this paper is JULES (the Joint UK Land Environment Simulator [Best et al ...
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There is considerable interest in the use of 2D hydraulic models for the prediction of instream habitat especially for complex hydraulic situations such as those found in braided rivers. The general assumption is that the greater spatial... more
There is considerable interest in the use of 2D hydraulic models for the prediction of instream habitat especially for complex hydraulic situations such as those found in braided rivers. The general assumption is that the greater spatial resolution of 2D models and their hydraulic modeling will give better predictions of instream habitat. We apply a 1D model and two 2D
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A guide to instream habitat survey methods ... NIWA Science and Technology Series No. 54 ... Published by NIWA Science Communication PO Box 14-901, Wellington, New Zealand 2008 ... Citation: Jowett, IG; Hayes, JW; Duncan, MJ (2008). A... more
A guide to instream habitat survey methods ... NIWA Science and Technology Series No. 54 ... Published by NIWA Science Communication PO Box 14-901, Wellington, New Zealand 2008 ... Citation: Jowett, IG; Hayes, JW; Duncan, MJ (2008). A guide to instream habitat survey ...
77ie Structure, Function and Management Implications of Fluvial Sedimentarv Svstems (Proceedings of an" J 7" J international symposium held at Alice Springs. Australia, September 2002). IAHS Publ. no. 276. 2002. New views of the... more
77ie Structure, Function and Management Implications of Fluvial Sedimentarv Svstems (Proceedings of an" J 7" J international symposium held at Alice Springs. Australia, September 2002). IAHS Publ. no. 276. 2002. New views of the morphodynamics of large braided rivers from high-...
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Hydrologic model simulations can only be deemed credible if the model structure is consistent with current understanding of hydrological processes. The necessary steps in building a numerical model are therefore to develop a perceptual... more
Hydrologic model simulations can only be deemed credible if the model structure is consistent with current understanding of hydrological processes. The necessary steps in building a numerical model are therefore to develop a perceptual model of how the catchment functions and a conceptual model that provides an overview of the major storages and fluxes of water in the catchment. This
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Research Interests: Depth, Soil moisture, Streamflow, Soils, Sol, and 4 moreRainfall, Runoff, Unsaturated Zone, and Rain water
It has long been recognized that soil moisture has a key role in controlling evapo- transpiration during dryer periods, as well as runoff processes, particularly saturation excess runoff. The temporal and spatial variability of moisture... more
It has long been recognized that soil moisture has a key role in controlling evapo- transpiration during dryer periods, as well as runoff processes, particularly saturation excess runoff. The temporal and spatial variability of moisture can be an important influence on the temporal and spatial characteristics of these processes. More recently, the role of soil moisture in controlling lateral flow processes has re- ceived close attention, with switching between persistent dry and wet states leading to switches between controls on spatial patterns of soil moisture and consequent changes in runoff behaviour. In this paper we will review results on the spatial and temporal variability of soil moisture at the small catchment scale, concentrating in particular on dominant controls and temporal changes in dominant controls. We will discuss the climatic and catchment characteristics under which switching between dominant controls is likely. We will also present results relating spatial soil moisture behaviour to soil moisture state and relating rainfall-runoff response to moisture state: in particular we investi- gated the relationships between the basin soil moisture dynamic and the occurrence of very extreme flood events. The spatial probability density function of soil moisture is bounded by wilting point and porosity. This bounding combined with catchment processes leads to a strong link between spatial variance and spatial mean soil mois- ture, with an initial increase in variance followed by a decrease as mean soil moisture increases from wilting point to saturation. Changes in the spatial control of soil mois- ture and the relationship between soil moisture and terrain also occur as the spatial controls on the soil moisture pattern change in response to mean soil moisture. Strong links between the changes in the spatial characteristics of soil moisture will be demon- strated and the potential of measurements of soil moisture to provide information on catchment state and rainfall-runoff response will be explored.