Chapter 5. The river environmental domains - results and technical discussion

Chapter 5. The river environmental domains - results and technical discussion

The Environmental Domain Analysis (EDA) resulted in a map that included 489 different river environment domains, many of which occurred in multiple patches. To avoid confusion it is worth defining some terms here. A patch refers to a single area that has been found by the analysis to be internally consistent in terms of the system controls on river development. A domain is composed of one or more patches that are similar. In other words, a domain is an internally consistent area, that can occur as spatially separate patches. These patches might be separated by small or large distances. All together, there were 129 thousand patches of river landscape identified in the state. The domains are named arbitrarily by number. The statewide EDA is shown in Figure 36.

Each domain tells you something about the local environment, and puts those local conditions in a state wide context. If you know which domain you are standing in, you know that your immediate surrounding will fit within the characteristic range of values of system controls for that domain, and you know where similar landscapes occur throughout the state. If, for example, you are standing on the Pinnacle Track on the very edge of the Mount Wellington Plateau, you are in a patch of domain number 211. This tells you that you are in a high relief area, with slopes that vary from moderate to very steep. You are on dolerite lithostructure, and the area has been subject to periglacial and possibly also aeolian processes, and was possibly covered by ice during the maximum glaciation. The climate is moderately and reliably wet, although not as wet as other areas of the state, and there is a tendency for a very intense rain event to occur every few years. You also know from the domain map that similar environments are found around the edge of the Ben Lomond Plateau, and around the northern edge of the Central Plateau.

The domains vary in spatial extent, from a minimum of 4 grid cells (16 ha) to some massive domains that cover hundreds of thousands of hectares. The biggest of these is number 93, which covers over 200,000 cells, or 12 % of the land area of the state. Domains typically occur as multiple patches, and patch size typically varies from 10s to 100s of hectares.

This presents a very complicated picture. Because of the number and diversity of domains, it is difficult if not impossible to examine the whole state at once and still be able to appreciate the amount of information in the analysis. However, it is possible to use these domains as the smallest unit in a hierarchical analysis of landscape. Domains represent relatively uniform landscapes that occur on a scale of 10’s to 100s of hectares. By identifying areas with similar patterns of domains, we can identify subregions, which occupy 10’s of square kilometres. Patterns in the distribution of subregions, and the way rivers flow through a sequence of subregions will identify river regions for the state. This last step is beyond the scope of this report, however sub regions have been identified for a case study area including the catchment of the upper Macquarie, and extending across to the Apsley catchment and east coast, and will soon be identified statewide.

Before looking at spatial patterns of domains, it is important to examine how they relate to the system controls on river development and behaviour. The basic concept of an environmental domain analysis is that each domain would reflect equally the influence of all the system controls, and that within each domain type would be found a relatively small range of values for each system control. In this way, when referring to any particular domain, you are also referring to a known discrete range of each system control, with little overlap with any other domain. However, in practice, this proved to be a difficult thing to achieve, for two reasons. Firstly, this neat ideal requires that all the system controls change in the same place, showing clearly where the edges of domains and regions occur. The upper edge of the Great Western

67 Chapter 5. The river environmental domains - results and technical discussion

N 50 0 50 100 150 200 Kilometres

Figure 36. The environmental domain analysis for the whole of Tasmania. Colours represent different domains. Note that it is not possible to produce 489 easily distinguishable colours. Bright colours covering large areas of the state each represent a single domain, but pale colours covering small areas may represent more than one domain.

68 Chapter 5. The river environmental domains - results and technical discussion

Tiers is an example of such a distinct boundary. As you step from the Central Plateau onto the face of the tiers, almost all of the system controls change simultaneously. Secondly, it also requires the perfect data set and computational tools for identifying these boundaries. As might be expected, although the result sometimes approached the ideal, neither the environment, the data, nor the computers cooperated fully.

The implication of the mixed success of the EDA procedure is that, although all domains are well defined in terms of the multivariate relationship between all system controls, some domains do include areas with a wide range of values for some system controls. For example, domain 93 covers areas where the slope varies widely. The average slope for the whole area of domain 93 is just under 8 degrees, but most of the domain lies between 1 and 19 degrees. Any one patch of domain 93 will contain only some of this range in slope. Similarly, the domain includes areas of basalt, dolerite, Parmeener and Mathinna lithostructure. Any one patch of domain 93 is likely to include only one of these lithostructures, but without checking the input data it is not possible to tell which. A result of this is that the domain analysis is more useful at the regional and subregional scale, which are well described by these average values, than at the scale of a single domain patch which can vary widely from the average condition for that domain.

The rest of this chapter discusses the reasons for this variation in the values of system controls within domains, considering first the categorical controls (process history and lithostructure) and then the continuous variables (topography and climate). We then consider the implications for the interpretation of the domain map, and consider how the analysis can be used at different spatial scales in a hierarchical analysis of river regions in the state.

An overview of the relationship between domains and system controls The categorical system controls – lithostructure and geomorphic process history The influence of the categorical system controls on the formation of domains was variable. For example, lithostructure appears to play an important role in defining around three quarters of the domains. However, in the remaining quarter the role of lithostructure was less clear. In this section we discuss why these different types of relationship between the domains and the system controls may have occurred.

Where a categorical system control has a clear relationship with other system controls, then it has a strong influence on the formation of the domains. So, for example, there appears to be a distinct relationship between granite lithostructure and the other system controls, because there is a very distinct suite of domains that occupies the granitic areas of the state and occur on almost no other lithostructure (Figure 37). Another way of describing this is to say that domains can either be classified as being almost entirely granitiod lithology, or entirely not granitoid. There are very few domains that are only partly granitoid (Figure 38). Within the group dominated by granites, the distribution of different domains reflects the climatic gradient from east to west, and smaller scale topographic variation. Granite is not the only categorical variable to have this strong influence on domain formation. Several other lithostructural elements and process history regions had a similar influence. These include the coastal sands and gravels, glacial sediments, undifferentiated Cainozoic sediments, mafic and ultramafics, folded quartzites, and carbonate lithostructural elements, and the present day periglacial process region.

The other categorical variables had less overriding influence over the domain formation. These include basalt, dolerite, Mathinna/Eldon groups, and the Parmeener Supergroup lithostructural elements, and aeolian, maximum glaciation, last glacial, karst and peat process regions. This means that there are many domains that represent a mix of lithostructural

69 Chapter 5. The river environmental domains - results and technical discussion elements, or only partly represent a process region. These domains to not identify landscape forms that are clearly associated with a single lithostructure. Rather, they have identified landscapes that the analysis suggests will have a similar effect on river form, despite the variability in lithostructure or process history, because of similarities in topography and climate. As a result, it seems that domains in these parts of Tasmania were more influenced by the topography and climate than either lithostructure or process history. There are a number of possible explanations for this, all of which are probably true somewhere in the state. They include a lack of any clear spatial relationship between these categorical variables and the other system controls, spatial relationships being present but too complex to easily identify, and artefacts of the environmental domain analysis procedure.

Figure 37. The occurrence of granitoid lithostructure (hatching) in the north part of the state, and the suite of domains that occupy those areas (shading). Note that the two areas match almost exactly, indicating that the granitoid lithostructural element had a strong influence on the formation of the domains.

It is possible that the lack of a clear spatial relationship is a true observation of the environment. This may be the case where there is a great deal of diversity within one system control. For example, the Mathinna & Eldon and Parmeener lithostructural elements both include a great deal of diversity. They are both thick sedimentary deposits, that range from fine mudstones to limestone and sandstone. The Mathinna & Eldon element is made more diverse by variable metamorphosis. Some of geomorphic process regions may also be very diverse. For example, the glacial process regions include erosional features caused by ice caps, cirque and valley glaciers, as well as the deposition features such as moraines. This diversity might prevent the identification of a clear relationship between these elements and the remaining system controls.

In contrast, in some situations the same landscape can form on two different lithostructures. An example of this is the uplifted plains described in ‘Other influences on stream geomorphology in Chapter 4 System Controls. These high plateaus can occur on any geology, and would confuse the relationship between lithostructure and topographic system controls. Also, sometimes the same shaped feature can be formed by different geomorphic processes. For example, a floodplain on a large river and a plain caused by karst solution of the underlying carbonate rocks are similar in terms of lithostructure (Cainozoic sediments) and topography (flat plain). As a result, these two features, with quite different origins, are sometimes included in the same domain. Domain 384 is an example of this.

70 Chapter 5. The river environmental domains - results and technical discussion

120 Granitoids 100 80 60 40

% covered 20 0 0 50 100 150 200 250 300 350 400 450 500 Domain

120 Dolerite 100 80 60 40

% covered 20 0 0 50 100 150 200 250 300 350 400 450 500 Domain

Figure 38. These graphs show the relationship between two of the lithostructural elements and the domain analysis. Granite has a strong influence on domain formation, and as a result domains tend to either be almost entirely granite, or almost entirely not granite. In contrast, dolerite had a less overriding influence on the domains, and there are many domains that are partly doleritic and partly some other lithostructure.

In some situations, the domain analysis may have identified real spatial relationships that are too complex to easily recognise, as would be the case where a landscape is characteristic of a combination of rock types, rather than a single lithostructure. This appears to be the case with dolerite and the Parmeener Supergroup lithostructural elements. Dolerite occurs in some quantity in 165 different river domains. Of these, 43 domains are over 90% dolerite, and presumably have identified purely dolerite landscape forms (for example domain 403 in Figure 39). The remaining 122 domains include anywhere between 1% and 89% dolerite. However, almost half of these partially dolerite domains are dominated not by one rock, but by the combination of dolerite and Parmeener Supergroup, often with some other rocks as well (see Figure 39). This suggests that these domains have identified a mixed dolerite and Parmeener landscape, a prospect that is reasonable enough given that these lithostructures frequently occur in close proximity to each other.

Mapping errors are another potential source of confusion in the relationship between domains and system controls. This will be a problem for many of the categorical system controls. The level of detail in the original geology mapping varies across the state from 1:25,000 to 1:250,000. In the east of the state, in areas that have only been mapped at 1:250,000 scale, large patches that are shown as dolerite actually often include small outcrops of Parmeener Supergroup rocks.134 Given this, it is not remarkable that the domains do not differentiate well between the two lithostructures. As well as problems caused by using such broad scale mapping, there is also the problem that lithostructure classes that would ideally be used as system controls were not always well mapped. This is particularly the case with relatively young deposits, such as floodplains and coarse slope deposits. Mapping errors are also likely in the process history system controls, as these were originally mapped at a 1:500,000 scale, and often required extrapolation between fragmentary boundaries mapped in the field.

71 Chapter 5. The river environmental domains - results and technical discussion

100% volcano seds

90% Tertiary seds

80% coarse slope Mathinna & Eldon 70% mafic & ultramafics 60% granitoids % are 50% glacial seds a 40% folded quartzite folded lutite 30% coastal seds 20% undifferentiated Cainozoic 10% carbonate

0% basalt Parmeener Domain dolerite

Figure 39. Examples of typical lithostructure composition of domains that include dolerite. Some domains are entirely dolerite, some are a combination of lithostructures that commonly occur together such as dolerite and the Parmeener Supergroup, while others contain a wide variety of lithostructure. Finally, dolerite sometimes occurs in very small percentages in domains dominated by slope deposits or soft sediments. This selection is intended to indicate the range of lithostructure composition, and is not necessarily a representative sample.

Finally, the computational procedures that formed the domains may be responsible for two more odd combinations of categorical system controls in a single domain. Firstly, an ‘edge effect’ can cause a domain dominated by a single lithostructural element to also include traces of surrounding elements. For example, dolerite also occurs in very small percentages on the margins of domains dominated by coarse slope deposits, and Cainozoic sediments (eg domains 183 and 446 in Figure 39). Secondly, some domains contain a wide variety of lithostructural elements, and this may be an artefact of the process by which domains were defined (see ‘Domain mapping’ in Chapter 3). This involved finding internally uniform areas, which formed the domains. However, once these were identified, there was a number of individual cells or very small patches remaining that were not similar to any large neighbouring patch. These unusual cells could either be an error in the data, or a truly rare patch of landscape such as an outcrop of atypical geology in the area, or a topographic feature such as cliff or waterfall. However, these cells were forcibly merged with whichever neighbour was least different. This final lumping could be the cause of domains such as number 8, which incorporates areas of each of the geomorphic process regions, and includes 12 of the 15 lithostructural elements.

The continuous system controls – climate and topography Ideally, the size and shape of the stream domains would reflect the dimensions of the system controls on landscape it represents in a manner that is intuitively easy to follow. Often this is the case, and large significant features can easily be seen on the domain map. For example, the divide between the south east of the state, which is dominated by flat topped dolerite mountains, and the south west, dominated by long jagged ridges of quartzite, is easy to see. On a slightly smaller scale, features such as the Davey-Olga strike valley are also clearly visible. However, at the smallest scale of 100’s of metres, domains do not always relate clearly to the underlying topography. Although it is not a universal rule, a single domain can include a wide range of values for topographic or climatic variables. This is demonstrated in the Figure 40, which shows the average and range of values for cross sectional curvature

72 Chapter 5. The river environmental domains - results and technical discussion

(calculated over a 3x3 cell window) and effective precipitation, for the first 30 domains. Similar graphs relating all 489 domains to all the continuous variables can be found in Appendix 3.

15 10 5 0 -5 -10

-15window)

Cross sectional -20 curvature m (600 -25 0 5 10 15 20 25 30 domain

2500 2000 1500 1000

Effective 500 precipitation 0 -500 0 5 10domain 15 20 25 30

Figure 40. Graphs showing the average and the range of values for cross sectional curvature and effective precipitation for the domains 1 – 30. Error bars are the 5th and 95th percentiles. There are several reasons for the wide range of values for topographic and climatic variables in some domains. These either relate to real patterns present in the environment, or to the data used to represent the environment and the computational tools used to process the data.

As was discussed for categorical variables, where a strong relationship exists in the environment between most of the system controls, a domain can be formed that includes a wide range of values for the remaining controls. Domain number 404 is an example of this. This domain occurs in karst plains in the west of the state, from the Arthur River in the northwest to the Olga valley in the south west. As can be seen in Figure 41, there is a clear relationship between this domain and lithostructure, the process history regions, most of the topography variables, and the climatic variables relating to the wettest day of the year. This strong relationship appears to have overridden the very large variability in the amount and reliability of effective precipitation that occurs across western Tasmania.

73 Chapter 5. The river environmental domains - results and technical discussion

404 250

200

150

100

50

0

-50

Figure 41. The range of each system control in domain 404. Note the large range for effective precipitation, and the coefficient of variation of effective precipitation, compared to the ranges of other system controls.

The data and computational procedures used to produce the domains are another probable source of large ranges in the values of continuous variables within a single domain.

The way in which continuous data is represented in domains depends on the scale of variation of the landscape, of the data that represents the landscape, and of the domains that are derived from that data. This analysis was based on a 200 m grid of Tasmania. The topography data was generated using a digital elevation model (DEM) at this scale, which was derived from 1:100,000 scale topography maps. Unfortunately, this 200 m grid is still too coarse to show some of the landscape shapes that are important to streams, particularly in very small catchments. Calculating topographic variables from the 200 m DEM using the smallest possible window size of 3 cells, or 600 m, results in very noisy data. Using a finer grid, such as a 25 m DEM, would represent the landscape much more faithfully. This is illustrated in Figure 42. Unfortunately, a sufficiently accurate 25 m DEM was not available for the whole state, and if it were would present difficulties with handling the volume of data. Using a 200 m grid required the processing of 4,715,000 data points, which is challenging enough for a desktop computer. An analysis of the whole state using a 25 m grid would require processing 64 times more data, or some 300 million points. As a result, we were forced to use the coarser scale data, and must bear in mind that some of the fine scale variation that is visible on a 1:25,000 topographic map is not well represented here. Larger features are well represented.

The different continuous system controls vary on different scales. Figure 43 compares effective precipitation with cross sectional curvature to illustrate this point. Domains that are strongly controlled by large scale variables such as climate or geology can include a wide range of values for variables that show fine scale patterns, such as topography.

Patch shape also has an effect on the range of system controls that are found within any one domain. For some reason, possibly related to the algorithm that defined the domains, these small patches tend to form squat and square shapes. However, as can be seen in Figure 43, the fine resolution spatial data tends to emphasise long thin shapes. As a result, each domain contains a wider range of topographic variables than if it conformed better to the underlying shape of the landscape. Possibly this is a question of relative scale, would be resolved by using a smaller grid.

74 Chapter 5. The river environmental domains - results and technical discussion

Figure 42. A comparison of cross sectional curvature calculated at two different scales. At the top is a 25 m digital elevation model, with cross sectional curvature calculated with a 15 cell or 375 m window. In the middle is the same area with cross sectional curvature calculated from the 200 m DEM using a 3 cell or 600 m window. Note the coarse grain of this image, and the fact that smaller features are not detected. The lowest image is the rivers and 10 m contours from the 1:25000 topography maps. The peak is Byatts Razorback, immediately east of Ben Lomond. The view is approximately 5 km from north to south.

75 Chapter 5. The river environmental domains - results and technical discussion

Effective precipitation Cross sectional curvature (range from -69 to 2500 mm) (600 m window)

Figure 43. Statewide maps of the system controls effective precipitation and cross sectional curvature (measured over 600 m). The climatic data shows gradual patterns of change across the state, while to topography data is so finely dissected that it is almost too fine to appreciate at this scale.

Conversely, it is also possible for domains to include too small a range values for each system control, creating a problem of too great a complexity in the domain map. This leads to the situation where what appears to be a topographically similar area, with similar geology, process history and climate, is divided into multiple domains. This is illustrated in Figure 44.

Finally, the way the domain analysis coped with single cells or very small patches that were similar to none of the surrounding domains may also have contributed to large ranges in measures of topography and climate within a single domain. As described in the categorical section, any such unusual cells were forced into whichever neighbouring domain was least different. This has the potential to greatly increase the range of topography and climate conditions in the receiving domain.

The net result is that it is difficult to use individual domains to interpret the landscape in fine detail. However, domains do occur in distinct assemblages that can be used to identify different landscape types. These domain assemblages reveal large scale patterns in the environment that can be used to identify areas where the same components of the landscape are found. These areas are described as sub regions, and are typically in the order of 10’s to 100’s of square kilometres. A sub region is not a uniform area, such as a plain or individual hill slope. Rather, it is uniform at a larger scale, because it includes a repeating pattern of plains and slopes that have similar character in the context of similar climatic and lithostructural elements. At this scale, the domain analysis appears to work very well as a method to objectively identify river landscapes. The next section of this chapter is devoted to identifying these sub regional areas in a case study area that includes the upper Macquarie catchment, and stretches east to include the Apsley River.

76 Chapter 5. The river environmental domains - results and technical discussion

River s Domain 145 Domain 233 Domain 256 Domain 438 20 m contours Domain 170 Domain 244 Domain 283 Domain 438 Domain 93 Domain 184 Domain 248 Domain 436 Domain 441

Figure 44. The headwaters of the Wye River and Lost Falls Creek in the Eastern Tiers. Note that the ridgelines and some small valleys all consist of one huge domain, number 93, but that a series of different small domains make up the major valleys. The overall pattern of domains is informative, but the presence of an individual patch of a single domain is less useful. Different shading represents different domains. Contour interval is 20 m.

Identifying larger scale patterns – mosaics and subregions in the Upper Macquarie Catchment

The river landscape can be usefully examined on a larger scale than that of individual domains. Domains occur together in characteristic mosaics, each of which represents a type of landscape. Mosaics are defined as areas of landscape which are made up of characteristic features. Whilst not necessarily similar, these features are typically associated with each other, forming a set of features distinct from all others in the state. These mosaics are a tool for identifying ‘sub-regional’ landscape units across the state. The process for identifying sub-regions involves mapping domain mosaic areas, and then classifying those areas to allow you to map sub regions across the state.

This process has not yet been completed at a statewide scale. However, mosaic areas have been identified in a case study area of some 3000 square kilometres, or around 4.5% of the state, containing patches of 93 different domains. The area includes the upper Macquarie River catchment, and stretches east to the coast and north to include the catchment of the Apsley River. Eighteen different mosaic areas were identified, on the basis that they had an assemblage of domains present that differed from neighbouring areas. These are shown in Figure 45, and graphs summarising the domains that comprise each mosaic can be found in Appendix 4. A detailed description of the landscapes represented by each mosaic, and the character of the rivers that run through them can be found in the next chapter. The next step, of classifying the mosaics and identifying which represent different occurrences of the same subregion needs to be done in the context of the whole state, and so is not presented here.

77 Chapter 5. The river environmental domains - results and technical discussion

The method proposed for identifying mosaics involved searching for ‘diagnostic’ domains or combinations of domains. These are domains which only occur in a particular mosaic. Once these are identified, a line drawn around their distribution identifies the extent of the mosaic. For many of these mosaic areas diagnostic sets of domains were relatively easily identified by examining the proportion of each domain found in a mosaic, as compared to its distribution across the whole study area. However, as mapping of the mosaics proceeded, two exceptions to this became apparent.

First, several mosaics are present that cover a very small area, and so are effectively too small to have a characteristic assemblage of domains. In this case, it is a question of judgement whether to merge the area with a surrounding mosaic or keep it separate because of similarities with other nearby mosaics, with which it will eventually be merged. To some extent, this problem is a product of the small case study area. Around the edges are slivers of larger mosaics that continue outside the case study area. Identification of river domain mosaics state wide would reduce this problem. However, there are also some mosaics that are simply very small.

Secondly, the idea of diagnostic domains or suites of domains is based on identifying the presence of distinctive components of the landscape. This works well for areas that have complex patterns in any of the system controls, particularly topography, because they have a relatively large number of domains. However, some areas are distinctive not for their complexity but for their simplicity, and so must be identified not by the presence of distinctive domains, but by their absence. These simple landscapes include for example the small plateau area at the very head of the Macquarie River. This area shares many characteristics with the surrounding landscape (low dolerite ridges, similar climate, uniform geomorphic process history) but lacks the narrow valleys found to the east or the relief found to the west. Such areas are easiest to identify visually using a GIS system.

Conclusions and improvements that could be made to the Environmental Domain Analysis. The domain analysis did not work quite as intended, and as a result many of the domains represent a wider variety of values of the system controls than ideal. This detracts from the ability to use individual domains to describe river landscapes. However, the domains are still suitable for identifying larger scale patterns in the river environment. These large scale patterns have the potential to be very useful in building a river regionalisation for the state.

The basic technique of the environmental domain analysis does have the potential to produce domains that represent distinct landscapes. Several improvements are recommended that would probably make a marked difference to the analysis. These are listed below. 1. Use the 25 m grid to calculate the topographic variables and to perform the environmental domain analysis. This would generate far smoother topographic data at fine scales, and so represent the environment more faithfully. It would also allow the shape of domains to follow the underlying landscape more closely. 2. When defining domains, allow small patches (less than 4 grid cells) that are not similar to any neighbouring patches to remain unattached to any domain. 3. Strategically improve some of the input data. For example, a major flaw in the lithostructural elements data are mapping errors and shortcomings the elements relating to sediments deposited during the Tertiary and Quaternary (the last 65 million years). In particular, the lack of a modern floodplain lithostructural element means that these features are included in the undifferentiated Cainozoic sediments. As a result, quite different materials are mapped as the same lithostructural element (for example, the Henty Dunes and the southern part of the Olga valley).

78 Chapter 5. The river environmental domains - results and technical discussion

4. Experiment with weighting the input data, and using fuzzy boundaries to represent uncertainty in the mapping, to see if you get domains that more faithfully follow lines of local similarity in the landscape. 5. The system control ‘driller’ described in Chapter 3 should be used in conjunction with the domain map. This GIS tool can present the system control data for an individual pixel, making it easier to look at the landscape at multiple scales, from region down to individual 200 m cell.

If such changes were made, the result would be a more robust regionalisation, and could also be more useful for making local management recommendations, as Wells28 attempted to do for headwater streams in the forestry estate.

Having said this, it is important to note that even with these shortcomings the present analysis does appear to be a useful way of looking at the variation in river landscapes across the state. It is a tool that reduces the huge and complex variation in the controls on river development and behaviour around the state to a manageable level, and so allows variation in landscape at any one place to be considered in the context of the whole state.

79 Chapter 5. The river environmental domains - results and technical discussion

Key to common domains 88 171 264 342 Apsley Uplands 93 181 280 349 97 184 281 384 132 206 283 417 140 223 322 418 145 244 275 438 170 248 326 441 10 0 10 20 Kilometres

Pink C

Midlands Western Uplands Eastern Uplands

Macquarie Apsley Lowlands Tier

Basalt Basin Eastern Tiers Crest

Pink B

Eastern Lowlands

Western Foothills

Midlands Boundary Pink A Eastern Foothills N

Figure 45. The mosaics identified in the case study area of the central east coast and the upper Macquarie catchments. The mosaic boundaries are drawn in black. Note that the domains are shaded to highlight different mosaics, and that the colours do not imply the degree of similarity between domains. 80 Chapter 6. Putting the picture together: linking river landscapes and river character

Chapter 6. Putting the picture together: linking river landscapes and river character

This chapter is devoted to consideration of how to use the river environmental domain analysis and the resulting mosaics of domains to describe river landscapes and to predict river character within those landscapes. It is based around the case study area of the Apsley and upper Macquarie catchments. Here we will take the mosaics of domains identified in the previous chapter, and describe the landscape each mosaic represents in terms of the domains they include, and how those domains relate to the system controls on river behaviour and development. Graphs showing how the domains in each mosaic relate to the system controls can be found in Appendix 5. For those areas for which we have field based assessments of river character, we will comment on the types of river that are associated with each landscape. These are simply the river characters that have been observed in each area, and do not constitute a comprehensive list of all river types likely to occur in that area. More detailed descriptions of the upper Macquarie River can be found in Appendix 9. The mosaics that occur only as slivers at the western extent of the study area are not discussed, because they are very small portions of large landscape features that are mostly outside the study area.

Things to consider when linking river landscapes to river character Before considering the case study, it is worth discussing some general principles that can be used to relate landscapes to the character of the rivers within those landscapes. A river’s form and character are in large part a response to its immediate environment. However, it is also a response to the landscape of the catchment upstream, and sometimes downstream. Where a river flows from one environment to another, it can have distinctive features that reflect that transition. In the previous chapter we identified mosaics of landscape at a subregional scale, where the same combinations of features occurred. A small range of river characters are found repeated in similar mosaics.

When viewed over short time frames, the immediate environment of a river channel has a huge influence on the form and behaviour of that section of river. The valley width and slope influence the erosive power of floodwaters and define the range of possible channel slopes. The material of which the valley walls and floor are formed is one of the main influences the erodibility of the channel boundaries, and therefore the ability of the river to change its form. Vegetation is also an important control. To give a fairly trivial example, a river with a meandering planform can only occur where valley slopes are low, while cascading step pool sequence requires a steep valley. Describing the local environment will not tell you precisely what types of streams will be found there, because that depends on other factors like the rest of the catchment and the disturbance history of the site as well, but it will narrow down the range of stream form and behaviour that is likely to be found there.

The river is also influenced by the upstream environment, which controls the timing and quantity of sediment and water supplied to an individual section of stream. Because of the influence of the catchment, two sections of river in similar local environments can potentially have quite different channel form and behaviour because of differences in the catchments upstream.

The size, shape, topography and climate of the catchment all influence the hydrology of the river downstream.99 The hydrology in turn influences the form and behaviour of the channel. For example, a short steep catchment will tend to have very ‘flashy’ flood behaviour, with the river rising and dropping quickly. In contrast, a similar sized catchment that has gentle slopes will produce a far more sluggish flood in response to the same rainfall.

81 Chapter 6. Putting the picture together: linking river landscapes and river character

The geology, topography and history of geomorphic processes all influence the quantity, dimensions and character of the sediment that is delivered to a reach (eg191). This will also affect the form and behaviour of the channel. For example, a catchment that is dominated by granite will tend to produce large quantities of sand and gravel, which will be deposited downstream to form easily erodible floodplains. In contrast, a dolerite catchment tends to produce a range of particle sizes from cobbles to a well structured clay which tends to make relatively stable floodplains. Topography has a huge influence on the amount of sediment that moves into a reach. Steep powerful sections of stream will be able to transport large quantities of sediment including large particles such as cobbles or boulders. Streams with gentle slopes will move relatively little sediment, and include none of the coarser fractions.

Distance attenuates the effects of upstream landscapes, particularly those relating to sediment supply. Predicting exactly how far these effects will be detected is very complex, and related to the sequence of river characters. As a general rule, however, it is the landscape immediately upstream that is most likely to compete with the local landscape as a significant influence on the river.

Distinct forms of river can be found where there is an abrupt transition between two distinct landscapes. When this occurs, very distinctive river characters are formed that reflect this rapid change in environmental controls, and often have features that are not found in the reaches up or downstream which more closely reflect their local conditions. Such transitional river forms can be very important, because they are often very sensitive to environmental change and disturbance. Transitional river forms include those that reflect a sudden decrease in stream power (alluvial fans), a sudden increase in stream power (nickpoint transitions), and the transition from riverine to marine processes (estuaries). Particular forms of the river types may be found in karst areas or where there are confined alluvial basins.

Alluvial fans occur where a steep, high energy river, supplied with large quantities of sediment from the surrounding hillsides, enters a wide, flat plain. Here, because of the low slopes and wide floodplain, there is a sudden decrease in stream power and the river is unable to transport the sediment that has been delivered from upstream. Instead, this gets deposited in a cone shaped feature where the hills meet the plain, called an alluvial fan (Figure 46). The rapid deposition of sediment, often in the channel, gives river in this section characteristics that are not found in either the gorge upstream or the true lowlands downstream. These include a tendency to avulse (rapidly change channel position) and to utilise at high flows a series of abandoned channels of various ages that disperse water across the surface of the fan.

Nickpoint transitions occur where stream power increases because of an increase in channel slope. Nickpoints, also known as headcuts, can occur in soft river deposited sediments, where they lead to gully erosion. They also occur on a much larger scale, where they are often associated with increases in slope in the wider landscape. For example, they occur where streams run over the edge of a plateau (eg the Great Western Tiers). They also occur in the downstream reaches of confined alluvial basins, where a river that is in a floodplain reach upstream enters a steep gorge.

Both alluvial fans and nickpoints are sensitive to changes in the balance between stream power and sediment delivery. Both features are at least partly alluvial, and have the potential to undergo major erosion or deposition should this balance be upset. Under glacial climates, a lack of vegetation and active periglacial processes provided massive amounts of sediment to streams which often did not have the capacity to transport it. As a result, alluvial fans grew bigger, and sediment was deposited in the upstream reaches of nickpoints. Under today’s climate, sediment delivery to streams has decreased, and many streams have created terraces by eroding sediment stored in alluvial fans and upstream of nickpoints. An example of this process occurring in contemporary timescales is in the mid reaches of the Spero River in western Tasmania.

82 Chapter 6. Putting the picture together: linking river landscapes and river character

Figure 46. Alluvial fans on small streams draining the flank of Twelvetrees Range near Strathgordon.

Alluvial fans and nickpoints occur in close proximity in confined alluvial basins. These are wide valleys with associated floodplain deposits that end where the valley becomes distinctly narrower and steeper. These are termed ‘dens’ in Tasmania (eg Big Den and Little Den on the Lake River). A particular sequence of river types is found in these landforms, starting with an alluvial fan and ending with a nickpoint where the river enters the downstream gorge.

Karst areas (that is, landscapes formed on soluble rocks such as limestone) have a particular influence on transition zones, as water is lost to cave systems or returned to the surface stream in springs. Water lost gradually to underlying karst can result in the loss of stream power at the surface, and as a result alluvial fan like features are formed. Where water returns to the surface in springs, very distinctive streams may form that are dominated by tufa, as limestone previously dissolved in the water is deposited to form mound springs, or hard and rocky river banks and beds.

Estuaries have not been considered in any detail in this project. However, they represent a very distinct landform where tidal processes, and the deposition of fine sediment interact with normal riverine processes.

So, the question now is how do you use this knowledge of the influence of landscapes on rivers to help predict river character using the sub-regional landscapes identified in the previous chapter, and described below. What is important is how the landscape influences the amount of water available to the stream (climate and catchment size), the stream power (mainly topographic factors such as valley floor slope, valley floor width), and the sediment supply (process history, lithology, valley wall slope, valley floor slope and width). Bear in mind that the landscapes identified by the mosaics of river environmental domains are not uniform, but are instead a collection of complimentary features, such as valleys and ridges, which are repeated throughout the mosaic area. Streams running through different landscape features will obviously have different characters. Also, waterways with different upstream catchments will be found in each landscape, and this also influences river character. As a result, there will be a variety of river types found in each landscape mosaic, depending on catchment size and which of the component parts of the landscape forms the immediate surrounding of that river. For example, in the East Draining Uplands of the Eastern Tiers,

83 Chapter 6. Putting the picture together: linking river landscapes and river character there are the trunk streams that occupy the main valleys, there are the steep tributary streams that flow down the valley walls, and small swampy streams found on the broad ridge tops.

Overview of the case study area The case study area stretches from the flanks Tunbridge Tier in the west across to Dolphin Sands and Moulting Lagoon in the East. It extends as far south as Tooms Lake, and as far north as Campbell Town in the west and the Douglas River in the east. This area covers four broad types of landscape. 1. The flank of the southern most extent of the Great Western Tiers and Tunbridge Tier are on the western boundary of the study area. These form a relatively steep landscape dominated by dolerite and Parmeener lithostructure. These are very large features, only a small part of which falls within the study area, which limits the ability to comment on the landscapes with any confidence. 2. The Central Midlands is a generally low relief landscape, formed on relatively young lithostructural elements of Tertiary aged basalt and sediments, and modern sediments. This area receives relatively little rainfall, and has high evaporation rates. This area is the floor of a basin that formed in the early Tertiary, and extends from the case study area to north of Longford. This basin is in places filled with up to 700 m of sediment,192 but only the shallow southern extension of the basin and sediments is found within the case study area. The landscape here is of sediments forming a relatively flat plain, with low ‘islands’ of bedrock poking through. There is also some basalt that adds some topographic variation to the Tertiary sediments. 3. The Eastern Tiers are the range that runs down the east coast of Tasmania. They were formed during the early Tertiary. Unlike the Great Western Tiers, the Eastern Tiers do not have a distinct plateau area. Rather, they have a broad and gentle crest that separates the steep eastern slopes from the gentler western slopes of the range. These slopes have been extensively eroded by rivers, particularly on the eastern face of the range where the short distance from the crest to the sea has created steep, powerful rivers. In the study area, the Eastern Tiers are dominated by dolerite, with small areas of Parmeener Supergroup. Further north, granite and Mathinna Group lithostructures are also found. 4. The Oyster Bay Graben is the low lying area occupied by Moulting Lagoon and the lower Swan and Apsley Rivers, as well as Great Oyster Bay itself. Like the Midlands, this area has low relief and is filled with Tertiary and Quaternary sediments that surround low bedrock hills.

These major landscape forms have influenced the domain mosaics that were identified in the previous chapter, and are described in detail below. On the whole, where more than one mosaic occurs within one of these broader landscapes, those mosaics tend to share many domains and so reflect the overall similarity of the landscape. In contrast, mosaics that come from different parts, for example the Eastern Tiers and the Midlands, have little in common, either in terms of the domains they include or the values of system controls that influenced the domains. Obviously, it is more difficult to draw meaningful boundaries between similar environments, particularly where the changes between those environments occur gradually. This difficulty is exacerbated by the tendency for many domains to relate to a broad range of values of the system controls, as discussed in the previous chapter. The Eastern Tiers section of the case study area includes eight different mosaic areas, all of which have some features in common, and some of which are very similar indeed. In this sense, the case study area is a very stringent test of the domain analysis as a basis for identifying regional and sub regional landscapes. A technique that can differentiate the subtle differences of the eastern and western slopes of the Eastern Tiers is likely to work anywhere in the state.

The relationship between the mosaics and the system control data that was used to develop the Environmental Domain Analysis is examined in Appendix 6.

84 Chapter 6. Putting the picture together: linking river landscapes and river character

The common features throughout the Tiers are largely represented by domain 93. The lithostructure and process history region values for this domain summarise the influences on the Eastern Tiers as a whole – that they are dominated by dolerite, and on the whole do not fall into any process region as mapped. Values of cross sectional curvature, measured at a large scale, show that this domain is largely restricted to the broad ridges found throughout the Tiers. It has on average a gentle slope of around 7 degrees, but includes a range from almost flat to very steep. Similarly, the domain has on average moderate to low relief, but also includes some high relief areas. To an extent, domain 93 appears to represent the ridgelines that are the remnants of Eastern Tiers that have not undergone large scale erosion since the area was uplifted. As such, it is not remarkable to find this domain throughout the Eastern Tiers area.

Apsley Uplands The character of the landscape Climatically, these domains are characteristic of a landscape with low effective precipitation, between 200 and 300 mm. This is fairly constant from year to year. The average maximum daily rainfall of around 60 mm is higher than average for the state, and in places is as high as anywhere in the state (eg domains 338, 446, 487, which make up 8.5 % of the mosaic between them). It also varies greatly from year to year. This landscape is one that is generally quite dry, but very wet days and their associated floods occur with much greater frequency than for most of the state.

As is the case with all hilly areas that include flat areas on ridges and in valleys, as well as steep high relief valley walls, the topography of this area is highly varied, and the range of values for the topographic system controls on the 16 or so domains found in this mosaic reflects this. The topography is related to the underlying lithostructure. There are three major lithostructural groupings evident in the domains.

Domains 93, 145, 170, 184, 233, 244, 248 and 438 reflect features that are characteristic of basalt, dolerite, Parmeener Supergroup or Mathinna & Eldon Group lithostructure. Together they cover almost 60% of the mosaic. These domains tend to occur on gentle to moderate slopes, typically between 2 and 14 degrees. They have moderate to high relief, with the relief index mostly just above 50. Cross sectional curvature measures suggest that they mostly form broad valleys, although there may be small scale ridges and valleys within these larger features.

Domains 87, 181, 338, 341, 446 and 487 indicate landscape features based on coarse slope deposits rather than bedrock. They cover 35% of the mosaic. These areas are more likely to be steep than bedrock features, but they do cover a larger range of slopes, between 5 and 20 %. They also tend to occur in areas of higher relief than bedrock domains. They occur on ridges and valleys.

Finally, domains 171 and 349 form a small but individualistic area, contributing just over 3 % of the mosaic. These are small patches of Cainozoic sediments, which in this area are either headwater swamps or floodplains on larger rivers. Predictably, they occur on the lowest slopes, in low relief areas in valleys.

None of the domains that characterise this mosaic indicate significant influence of any of the geomorphic process regions as mapped for this analysis. A map of periglacial activity during the last glacial maximum would no doubt contribute this system control.

Note that this area is quite similar to the East Draining Uplands of the Eastern Tiers in terms of process history, topography and most climate measures. It differs mainly in terms of

85 Chapter 6. Putting the picture together: linking river landscapes and river character maximum daily rainfall, which is has a tendency to be slightly higher here, and lithostructure, which includes large areas of slope deposit that are not mapped in the Eastern Uplands. However, to some extent this is an artefact of the geology mapping, as it is probable that slope deposits are present on steep slopes throughout the Eastern Tiers.

The character of the rivers A lack of field work in this area limits comments on the potential range of river characters. From work in other areas of the state, however, we can say that the combination of dolerite lithostructure and steep slopes covered by coarse slope deposits means there is potential for small streams on steep slopes to flow underground. These often emerge as surface channels at the contact with the underlying Mathinna or Parmeener bedrock.

Apsley Lowlands The character of the landscape Climatically, this area is fairly similar to the Apsley uplands. The domains here are also characteristic of low effective precipitation, between 200 and 300 mm. This is fairly constant from year to year. The average maximum daily rainfall of around 60 mm is higher than average for the state. It also varies greatly from year to year. This landscape is one that is generally quite dry, but very wet days and their associated floods occur with much greater frequency than for most of the state.

There is a strong relationship between topography and lithostructure. Around three quarters of the area of this mosaic is covered by domains indicative of soft sediments of Tertiary or undifferentiated Cainozoic age (domains 171, 349, 377 and 384). These sediments include some slope deposits (probably dominated by small rock fragments and soil), valley fills including modern floodplains, and also some coastal deposits. They characteristically have very low slopes, with most of the areas less than 5 degrees, and low relief, with the relief index almost always well below 60. The measures of landscape curvature indicate that these domains mostly fall either on flat ground or in broad valleys. This area also has some similarities with flat areas influenced by peat, karst or aeolian process history.

In contrast, the domains 93, 244 and 181 that make up most of the remainder of the mosaic are indicative of landscape features formed on bedrock or coarse slope deposit lithostructure, with much steeper and more variable topography. The features found on the bedrock are typical of dolerite, Parmeener, or Mathinna rocks. These domains all include a wide range of slopes, from only a few degrees to over 20 degrees. Similarly, the relief index can be over 100. Profile and cross sectional curvature measures show that these domains can form either ridges or valleys.

This mosaic represents a landscape that on the whole very flat and dry, consisting for the most part of soft sediments. However, around the margins of the mosaic are bedrock areas that usually have steeper slopes and higher relief.

The character of the rivers Common features of the rivers and streams of this mosaic are likely to be related to the scarcity of bedrock controls and the generally low gradients of the landscape. This leads to the development of features typically found on alluvial fans or in floodplain reaches, where the streams have deposited the sediment through which they run, and so have the ability to erode bed and banks to adjust the channel dimensions or planform in response to any disturbance. The character of any individual section of stream will also depend on its catchment size, and on the nature of the upstream reaches.

86 Chapter 6. Putting the picture together: linking river landscapes and river character

Fieldwork in this mosaic was restricted to two segments of the Apsley River. This means that comments on river character in this mosaic is restricted to large trunk streams. It is likely that smaller streams would have a different character, possibly more strongly influenced by their local environment.

The two reaches of the Apsley River in this mosaic have markedly different characters, which can be attributed partly to the influence of upstream and downstream reaches, and partly to variations in the character of the local landscape.

The Apsley River first enters this mosaic immediately downstream of the Apsley Gorge and the Douglas Apsley National Park. Here the river has just exited the East Draining Uplands mosaic of the Eastern Tiers, where rivers are relatively powerful and capable of transporting large sediment loads. In a few kilometres, the river enters a southern extension of the Apsley Uplands mosaic, before entering a final lowland plain that gradually grades into the estuary and saltmarshes of the Apsley Marshes.

Where the river first leaves the Eastern Uplands and enters the Lowlands mosaic, there is a marked decrease in slope, from 0.05% to 0.004%, as well as a widening in the valley from a narrow gorge to an alluvial plain. On entering the plain the river suffers a sharp drop in stream power, and is no longer able to transport the considerable quantities of sediment that have moved through the gorge. As a result, rather than immediately changing form to a low energy floodplain river, the river has a transitional form. It has deposited much of its load of gravel, cobbles and boulders to form an alluvial fan. Because the river here is still relatively steep, and the sediments are erodible, it is one of the most powerful and active sections of river in this subregion. Disturbance to the river or riparian vegetation has the potential to cause large scale erosion and channel enlargement, and this has in fact occurred in the top section of this plain. This behaviour is exacerbated by the relatively frequent occurrence of large rainfall events, which drive large powerful floods. However, at the downstream end of the plain, the river is far less powerful because of a backwater effect from the downstream valley control. Here it has a narrow, very sinuous meandering channel. This can be seen at the Rosedale Road crossing.

Figure 47. The Apsley River on entering this subregion forms an alluvial fan. The river has incised this large channel through the fan.

87 Chapter 6. Putting the picture together: linking river landscapes and river character

Where the river enters the Apsley Lowlands mosaic for the second time, the upstream context is rather different. Rather than a steep and narrow gorge, the river has just left a short segment of low gradient confined valley that has fairly low stream power, and supplies little sediment to the river downstream. As a result, there is far less evidence of transitional features. Rather than the steep, alluvial fan found upstream, the river here moves straight into its very low gradient (0.001% slope) form, the broadwater sequence. This is a sequence of very large pools, typically in the order of several metres in depth and 100 m long. These pools tend to form where the floodplain is constricted by either a bedrock outcrop or a large river terrace. Between these pools, the channel is very small, and may be very sinuous. Broadwater sequences are described in more detail in the Appendix 9, which describes the upper Macquarie River.

Table 2. River characters observed in the Apsley Lowlands landscape mosaic. River character Context Catchment size Alluvial fan Where a steep high energy river Trunk stream with a large bedload first enters the plain. Meandering river In very low slope and low energy Trunk stream areas. Broadwater sequence In low slope and low energy areas Trunk stream occasionally influenced by bedrock or large river terraces.

Figure 48. A broadwater pool on the lower Apsley River.

88 Chapter 6. Putting the picture together: linking river landscapes and river character

Figure 49. The small meandering channel immediately downstream of the broadwater shown in Figure 48.

Crest of the Eastern Tiers The character of the landscape The landscape of this area is typical of one dominated by dolerite, in combination with Parmeener Supergroup or Mathinna Group rocks, and possibly some basalt. None of the domains covering this area fall in any quantity within geomorphic process regions mapped for this project. Climatically, the area has a moderately dry climate. The area would probably fall into a map of uplifted plains, if it was available (see Other influences on stream geomorphology in Chapter 4). Effective precipitation is most commonly between 200 and 300 mm, but in the wetter areas may be as much as 700mm. It is fairly reliable from year to year. For all domains the maximum daily rainfall is around 50 to 60 mm, which is slightly above average for the state. For most domains, maximum daily rainfall is also more variable than average for the state. In terms of all of these system controls, this mosaic varies little from others of the Eastern Tiers.

The crest of the Eastern Tiers is topographically diverse, as it includes some very steep slopes and high relief areas as well as broad flats. However, its distinctive character comes from the dominance of flat or gently sloping areas, influenced by the flat lying dolerite bedrock or the alluvial flats formed by river deposition. River catchments are typically small, and the often low gradient small streams have not had the power to erode deep valleys since the landscape was uplifted in the early Tertiary. This is reflected in the huge 81% of this mosaic is covered by domain 93, which appears to represent the least eroded portions of the Eastern Tiers.

The overall flat and open nature of this landscape is reflected in the average values of cross sectional curvature for the domains that make up this landscape. These for the most part suggest a landscape lacking narrow ridges and valleys (domains 93, 171, 184, 233 and 384), instead consisting of broad gentle valleys and ridges (domains 93, 233, 244, 384, 438 and 441). This mosaic area was defined not by the presence of particular domains, but by the absence of those which characterised surrounding mosaics. These included 145 and 170, which are present in the eastern uplands and indicate landscapes with large valleys.

The character of the rivers This area was not visited during the field program.

89 Chapter 6. Putting the picture together: linking river landscapes and river character

East Draining Uplands The character of the landscape This area is similar to many other mosaics of the Eastern Tiers. The landscape is typical of one dominated by dolerite, in combination with Parmeener Supergroup or Mathinna Group rocks, and possibly some basalt. None of the domains covering this area fall in any quantity within geomorphic process regions mapped for this project. Climatically, the area has a moderately dry climate. Effective precipitation is most commonly between 200 and 300 mm, but in the may be as much as 700mm. It is fairly reliable from year to year. For all domains the maximum daily rainfall is around 50 to 60 mm, which is slightly above average for the state. For most domains, maximum daily rainfall is also more variable than average for the state.

This mosaic is dominated by the broad, gently sloping ridges that dominate all of the Eastern Tiers. However, the distinctive component of this landscape is deep valleys that have been cut through the eastern flank of the Tiers. These valleys have been formed by the steep high energy rivers that drop from 700 or 800 metres from the crest of the Tiers to the coast over only 30 or 40 km. At their base, these valleys are often too narrow for significant floodplains to form beside the river channel. Although such valleys do occasionally occur in other parts the Tiers, in no other area do they occur over such a large proportion of the river systems, because no other area has the same huge drop in altitude over such a short distance. A further distinctive feature is the parallel drainage pattern, as the streams run straight down the steep face of the Tiers.

The large scale modification of this part of the Tiers is reflected in the relative proportions of the landscape represented by domain 93. This domain represents the broad ridges and peaks found throughout the Eastern Tiers. It occupies some 55% of the area of the east draining uplands, a proportion that is small in comparison to other Eastern Tiers mosaics which range from 81 to 68 %. This relatively small proportion of 93 reflects the large area of this mosaic that has been eroded into deep valleys.

The steep nature of the valley sides in this landscape is reflected in the relatively large area of domains such as number 244, 248 and 283 that represent very steep and high relief landscapes. The cross sectional curvature data suggests that this area is still dominated by broad gently sloping ridges (domain 93), but also includes domains characteristic of broad valleys (for example domain 145), and both narrow ridges and valleys (domains 170, 184, and 145, 244, 248, 438 receptively). Many of these distinctive domains were used to separate this mosaic from surrounding areas. Domains 145, 184, 233, 248 and 283 are present in the eastern uplands mosaics, but absent from the eastern foothills. These are indicative of the steep slopes and deep valleys. The boundary with the western draining portion of the Tiers is marked by the abundance on the eastern side of domains 145, 170, 244, 283 and 438, and the absence of 305, 368 and 441, which occur mainly on the western draining slopes.

The character of the rivers This mosaic represents a highly variable landscape, and as a result the streams themselves also vary widely in character. Stream character responds to valley slope and confinement, and the degree of bedrock controls. Fieldwork in this area included the upper Wye River, the Macquarie River and the Apsley River.

Although the distinctive component of this landscape mosaic is the steep and narrow valleys, there is also a large area of gentle relief to be found between and upstream of those valleys. The headwaters of many streams occur on these low slope areas, and can be described as small catchment low gradient streams. Shaws Bogs, in the headwaters of the Wye River are an example of this (Figure 50). Channels are typically small and dominated by vegetation. It

90 Chapter 6. Putting the picture together: linking river landscapes and river character is possible that a continuous channel would not be present when these areas are in natural condition.

Figure 50. The upper Wye River in Shaws Bogs. In some cases, such low slope areas are found on larger streams. The Macquarie River at Longmarsh is an example of this. Here, in a generally steep section of river, the Macquarie enters a small alluvial basin with very low slopes. There is a sequence of transitional river characters in response to the lowering of stream power and ever decreasing slope. This is known locally as a ‘den sequence’, after the enclosed basins Big Den and Little Den on the Lake River. A den sequence consists of an alluvial fan reach, where the river deposits coarse bed material and may maintain multiple channels, a meandering reach, and a swamp reach.

Figure 51. A meandering section of the Macquarie River at Longmarsh. On steeper slopes too a variety of stream characters are found. Most common in this area are steep valley confined rivers. These occur in steep valleys, where floodplains are restricted to narrow benches between the river and valley wall, or occasional pockets where the valley is temporarily wider. These streams have coarse gravel beds, with pools and riffles. Bedrock is occasionally present in the stream bed or banks. The Macquarie River upstream of Longmarsh is an example of this type of river (Figure 52).

91 Chapter 6. Putting the picture together: linking river landscapes and river character

Figure 52. A steep valley confined reach of the Macquarie River upstream of Longmarsh. In some cases, the valley is sufficiently narrow and steep to be called a gorge. Here, bedrock is a constant control on the stream bed and banks. The Apsley River in the Apsley Gorge is an example of this stream character (Figure 53).

Figure 53. The Apsley River in the Apsley Gorge.

Table 3. River characters observed in the East Draining Uplands landscape mosaic. Stream character Context Small catchment low gradient On gently sloping plateaus and ridge crests streams Den sequence In enclosed alluvial basins Steep valley confined In steep narrow valleys Gorge In sections of valley that are sufficiently steep and narrow that bedrock controls the stream bed and banks

92 Chapter 6. Putting the picture together: linking river landscapes and river character

East Draining Foothills The character of the landscape Like many other mosaics of the Eastern Tiers, this landscape is within the typical range of those dominated by dolerite, in combination with Parmeener Supergroup or Mathinna Group rocks, and possibly some basalt. None of the domains covering this area fall in any quantity within geomorphic process regions mapped for this project. Climatically, the area has a moderately dry climate. Effective precipitation is most commonly between 200 and 300 mm, but in the may be as much as 700mm. It is fairly reliable from year to year. For all domains the maximum daily rainfall is around 50 to 60 mm, which is slightly above average for the state. For most domains, maximum daily rainfall is also more variable than average for the state.

These foothills flank the eastern edge of the Eastern Tiers. As with all components of the Eastern Tiers, this landscape does include some areas of high relief, and quite a few steep slopes. However, it is generally a lower relief landscape than the East draining uplands. Ridges have broad flat crests. Valleys are generally not as deep, and are less likely to be narrow and confined. Rather, there are more frequent strips and pockets of floodplains between the river and the valley wall. These wider valley floors and gentler hill slopes means that slope processes are less likely to deliver sediment to streams, and the streams are less powerful and so less able to move the sediment.

Once again, domain 93, which indicates the broad ridges and moderate relief and slopes that are common to all Eastern Tiers landscapes dominates here. It covers over 70% of this mosaic. The remaining domains that dominate the mosaic are all indicative of landscapes with variable slope and relief, with broad gentle valleys and ridges, and narrow valleys that are less distinct than those of the eastern uplands. However, this part of the landscape is generally lacking in extreme topographical features of either very high relief steep areas, or very large flat areas, and the domains themselves reflect this in their total lack of distinctive character. The domains absent from this area include some, but not all of those that are indicative of very distinct valleys high relief and steep slopes (domains 248 and 283).

The character of the rivers This area was not visited during the field program.

East Draining Lowlands The character of the landscape The distinctive climatic feature of this mosaic is the low effective precipitation. The bulk of this mosaic is likely to receive less than 150 mm excess rainfall in an average year. The year to year variability is roughly average for the state, which is similar to the Midlands but less reliable than the rainfall of the Eastern Tiers. At around 50 mm, the average maximum daily rainfall is just above the average for the state. However, the coefficient of variation indicates that this wettest day varies greatly in intensity from year to year.

There is a relationship between topography, process history and lithostructure. Domain 417, which dominates this area, contributing over 60% of the mosaic, represents a landscape based on undifferentiated Cainozoic sediments that have been influenced by aeolian processes. In this area, the Cainozoic sediments are likely to include aeolian, coastal, river and shallow marine sediments. These areas have very low slopes (almost always less than 5 degrees) and relief (the relief index is usually under 20). The measures of curvature also indicate flat ground.

93 Chapter 6. Putting the picture together: linking river landscapes and river character

Domains 349 and 171 represent just under 7% of the mosaic. This domain highlights areas where undifferentiated Cainozoic sediments occur in areas with greater slopes and relief. Here, the Cainozoic sediments are more likely to include river sediments and fine slope deposits, occurring at the margins of the coastal plain. These areas are not associated with the aeolian process region.

Domain 281 is associated with sediments that have been identified as being of Tertiary age. These are largely remnants of giant alluvial fans, deposited millions of years ago by the rivers draining the Eastern Tiers. During the last 2 million years these fans have been eroded, and now the remnants are some of the highest ground within the East Draining Lowlands area. These remnants now only occur on the drainage divides between the east draining streams. This is reflected in the comparatively high values for relief in this domain.

Domain 93 contributes around 15% of the area of this mosaic, and represents the bedrock hillsides that border the lowlands.

The character of the rivers As with all lowland areas, the character of the rivers depends on whether they are responding to a major change in environment and so present a transitional character, or whether they are largely a response to their immediate landscape. In this area, fieldwork has been restricted to the lower Wye River, which is an example of the former situation. Only a short section of river exists between the steep confining valleys of the uplands, and the estuary. In this reach it has formed an alluvial fan. Where it enters the lowland landscape, it has a coarse gravel and cobble bed. There are secondary channels that distribute water across the fan during floods. As you go further downstream, the gravel on the river bed gets gradually finer.

Figure 54. The alluvial fan reach of the Wye River, from the confined valley just visible on the left of the photo to the confluence with the tidal reach of the Swan River on the right. Note the secondary channel crossing the floodplain, and the narrowing of the main channel as you move downstream. Other rivers do flow for a sufficient distance through this landscape to reflect the character of the lowlands themselves, rather than just the transitional features of an alluvial fan. However, these were not examined in the field.

94 Chapter 6. Putting the picture together: linking river landscapes and river character

Table 4. River characters observed in the East Draining Lowlands landscape mosaic. River character Context Alluvial fan Where a steep high energy river first encounters the low slopes of the plains.

West Draining Uplands The character of the landscape As is typical for the mosaics of the Eastern Tiers, dolerite in combination with Parmeener Supergroup or Mathinna Group rocks, and some basalt dominate this landscape. None of the domains covering this area fall in any quantity within geomorphic process regions mapped for this project. Climatically, the area has a moderately dry climate. Effective precipitation is most commonly between 200 and 300 mm, but in the may be as much as 700mm. It is fairly reliable from year to year. For all domains the maximum daily rainfall is around 50 to 60 mm, which is slightly above average for the state. For most domains, maximum daily rainfall is also more variable than average for the state.

This landscape has many similarities to the eastern draining uplands landscape. It frequently has high relief, and very steep slopes. There are sections of very narrow and deep valley, and areas of broad, flat topped ridges. However, overall the dip of the landscape to the west is not as steep as to the east of the Tiers Crest. The effect of these gentler slopes on stream character is exacerbated by the courses that streams follow down this western face of the Tiers. Rather than running straight from the top of the range to the lowlands, as is the case in the Eastern Uplands, they follow more indirect courses, possibly influenced by structures in the underlying dolerite. This means that, because the fall in the river occurs over a greater distance, the trunk rivers of this area have far lower gradients than those of the east. This has important implications for the power of these streams.

Domain 93, which is indicative of uneroded remnants of the Eastern Tiers, covers roughly two thirds of this mosaic area. The remaining domains are indicative of landscapes with a range of slopes and relief, dominated by broad flat ridges and distinct valleys. The landscape can be separated from the eastern draining slopes by the presence of domains 305 and 368, and the absence of 244, 170, 438 and 283.

The character of the rivers Field work in this area was restricted to the Macquarie River, which at this point has a large catchment, around 126km2. No smaller streams were examined in the field, and it is likely that these would have different characters to the Macquarie. Apart form a short section of gorge, channel slopes on the Macquarie are typically moderate, and the river is frequently confined in a narrow valley which prevents floodwaters from spreading out, and controls any lateral movement of the channel. However, there are many short reaches where the valley is wide enough for floodplains to develop on one or both banks. These reaches are too short for the river to develop an alluvial character, as it soon is in contact with the valley wall again.

Table 5. River characters observed in the West Draining Uplands landscape mosaic. Stream character Context Low gradient valley confined In narrow valleys. Often, the valley widens sufficiently to allow floodplain development for a short distance. Gorge In sections of valley that are sufficiently steep and narrow that bedrock is the dominant control on the stream bed and banks

95 Chapter 6. Putting the picture together: linking river landscapes and river character

West Draining Basalt Basin The character of the landscape This is a relatively small area of just over 3000 ha. It is totally enclosed by the west draining uplands. It is notable because of the presence of domains that are not found in the surrounding area, and the absence of most of the domains that are distinctive in the west draining uplands. It is clear form the topographic and lithostructural elements maps that this area owes its distinctive nature to several patches of basalt and associated soft sediments.

As with other mosaics of the Eastern Tiers, this area is dominated by domain 93. This domain has been described above. Note that a proportion of this domain covers basalt areas, and it appears that this is the case in this mosaic, as roughly a third of the area is covered by basalt.

Within the study area, domains 384, 349, 171 and 216 are largely restricted to this mosaic. Together they occupy 35 % of the mosaic. They are all indicative of very flat environments that are dominated by Cainozoic sediments. All have average slopes below 4 degrees, and the ranges are typically less than 10 degrees. Values for relief are typically fairly low, and cross sectional curvature values are, with the exception of domain 171, near zero, indicating a flat landscape. Undifferentiated Cainozoic sediments cover all of these domains. These can include any Tertiary or Quaternary sediment whose exact origins are unknown, and include floodplain deposits. There is also a very small patch of domain 216, which is characteristic of Tertiary sediments.

Climatically, all these domains indicate areas of low and unreliable effective precipitation. Moderate to high values of maximum daily rainfall, and the high degree of variability of this statistic between years suggests that this area may occasionally be on the receiving end of large rain events.

The character of the rivers No streams in this mosaic were examined during fieldwork.

The Pink Mosaics The character of the landscape Three areas within the case study area do not have a clear relationship to the landscapes in which they occur. They are referred to as the pink mosaics, after the chance assigned colours of the dominant domains. Two of the three mosaics are striking similar in terms of the range and proportion of contributing domains. The third mosaic varies slightly from this pattern, possibly because it covers a very small area. Because of their similarity, these three mosaics are discussed together to avoid repetition.

The pink mosaics appear to represent a curious group of landforms, where there is little clear relationship between lithostructure and topography. The extent to which these mosaics indicate a real set of features in the environment, or simply an artefact of the Environmental Domain Analysis procedure is not clear. This may become clearer when the domain map is analysed on a state wide scale, rather than being restricted to the case study area. It is notable that almost all the domains found in any quantity in these areas contain up to 6 different lithostructural elements, typically including basalt, dolerite, the Parmeener Supergroup, the Mathinna and Eldon Groups, the volcano-sedimentary sequences, and the Rocky Cape Group. The common feature of these rocks is a tendency to support flat landscapes, either because of their flat lying structure (eg basalt, dolerite and Parmeener rocks), or because in many areas of the state they support flat erosion surfaces (eg the Mathinna Plains). The most likely explanation for this is that these domains represent areas where a similar topographic form

96 Chapter 6. Putting the picture together: linking river landscapes and river character occurs on this range of lithostructures because geomorphic events have disrupted the development any characteristic topographic form that is usually associated with those rocks. It is possible that these areas are transitional features, occurring where large river systems cross from a lowland region into a higher altitude area. In the case study area, the main patches occur on the Macquarie River and the Elizabeth River.

Climatically, these domains are characteristic of fairly dry landscapes (effective precipitation usually under 400 mm). This is likely to vary relatively little from year to year, although drier areas are more likely to be variable. The maximum daily rainfall is slightly above average for the state between 50 and 60 mm.

Topographically, these areas are characterised by a combination of gently rolling hills and some very steep slopes. Domains such as 248, 305 and 322 are all characteristic of landscapes with steep slopes and high to moderate relief. These domains make up around 20 % of the pink mosaic area. In comparison, domains such as 418, 264, 280, and 439 are indicative of areas of generally low slopes and low to moderate relief. These domains contribute around 40 % of the mosaic area.

This collection of features can be assembled into quite different landscapes. On the Macquarie River, the river is at the same general elevation as the rolling hills, and the steep slopes tend to occur around the boundaries of the mosaic, and the river is not particularly steep or confined. In contrast, the Elizabeth River has cut Staircase Gorge through higher elevation gently rolling hills. Here, the steep slopes occur immediately beside the river rather than at the margins of the mosaic, and the river is both steep and confined in a narrow valley. This does detract from the usefulness of these mosaics as a predictor of river type, because the two landscapes described here have markedly different implications for both valley confinement and river slope, which are very important controls on stream form and behaviour.

The character of the rivers With the exception of one reach of the Macquarie River, these areas have received relatively little attention in the field, so only limited comments can be made on the river characters that occur in them. However, it is obvious that widely varying river characters are possible, depending on whether the river occurs on the same level as the rolling hills, or as a gorge that winds its way between those hills.

The Macquarie River is an example of the former arrangement. In this section, the river has a moderately low gradient of around 0.01%, and runs through a valley of irregular width. The bedrock valley walls and floor exert a strong control on both the lateral and vertical movement of the river. In some sections bedrock valley walls are close to both banks. Bedrock can also control the river bed in these places, often as a relatively flat sheet of dolerite over which the river flows in shallow channels. Such controls frequently occur at the downstream end of large pools. Between these bedrock controls lie short alluvial sections, where the valley has sufficient width to allow the deposition of a floodplain. In these sections, the river has a pool and riffle sequence and a cobble bed. Floodplains are typically dark organic fine material overlying cobbles and gravel. These sections are never long enough for the river to develop the characteristics of a truly alluvial river, such as a meandering planform. In many cases, the floodplains appear inactive, and may largely be relict features formed during glacial climates when sediment loads in the Macquarie would have been much larger. The tributaries of the Macquarie in this area were not examined in any detail. However, as with the trunk stream, it is likely that they are alternatively alluvial and bedrock controlled. The smaller tributaries appear to be prone to minor incision.

97 Chapter 6. Putting the picture together: linking river landscapes and river character

In contrast, the Elizabeth River in this mosaic runs through Staircase Gorge. The average slope of this section is 0.019 %, and for short sections this could be much steeper. This river was not examined during fieldwork. However, because of its steep slope and very narrow valley it is likely to be a relatively powerful section of river, with relatively little sediment stored as alluvium and common bedrock control of the bad and banks.

Eastern Tiers Western Foothills The character of the landscape This mosaic runs down the inland edge of the Eastern Tiers. It is one of two distinct mosaics that appear to reflect the transition between the high relief and relatively high rainfall of the Eastern Tiers and the flat dry landscape of the Midlands. The domain composition of the mosaic reflects the transitional nature of this area. Of the 14 domains that contribute to this mosaic, 3 are shared with Eastern Tiers mosaics (domains 93, 170 and 208), 6 are shared with the Midlands mosaics (domains 88, 155, 206, 223, 247 and 310), and the remaining 5 are restricted to this area.

This mosaic differs most markedly from the Eastern Tiers in terms of climate. While the Eastern Tiers are typical of a moderately dry climate, their western foothills have much more in common with the dry rainshadow area of the Midlands. While the domains that are shared with the Eastern Tiers show a range of effective precipitation from very dry to average for the state, those that are restricted to this mosaic or shared with midlands mosaics are indicative of one of the driest areas in Tasmania. Effective precipitation ranges from almost 0 to only a few hundred millimetres a year. It is also more variable than in the wetter areas to the east. The wettest day of the average year is also slightly less than to the east, although the variability in this statistic is similar.

There is less difference between the western foothills and the main body of the Eastern Tiers in terms of process history regions, lithostructure and topography. Several domains are associated with landforms indicative of aeolian process history region (domains 140, 206, and 247). In terms of lithostructure, the domains suggest that like the bulk of the Eastern Tiers, this area is typical of those formed from a combination of dolerite, basalt and Parmeener Supergroup rocks, although the basalt contribution to landscape form appears stronger here. Also, domain 247 suggests that a small component of this mosaic (1.8%) is characteristic of Cainozoic sediment features. Topographically, the area has generally lower slopes than the Tiers, typically less than 10 degrees. Particularly notable is that no domain present here represent extremely steep components of the landscape. Similarly, relief is lower, with the relief index typically between 30 and 60, as compared to between 40 and 100 in the east. The measures of curvature indicate that this gently rolling landscape does in fact include broad ridges and valleys, but that narrow features are less common.

The character of the rivers In the case study area, this mosaic occurs as a thin band that runs between the Midlands mosaics and the Eastern Tiers. This means that most large rivers cross the mosaic in only a few hundred meters. Given that this mosaic is defined largely through climatic changes, it is unlikely to result in a visible change in river character over such a short distance. It may be that small streams with catchments entirely within this area have a distinctive character, but this was not assessed during field work.

98 Chapter 6. Putting the picture together: linking river landscapes and river character

Midlands boundary and Macquarie Tier The character of the landscape It is considered that the Midlands boundary and Macquarie Tier mosaics are so similar that they are representatives of the same subregion. In order to avoid describing the same landscape twice, they are discussed together here.

These mosaics represent another stage in the transition between the relatively wet and high relief Eastern Tiers, and the flat dry midlands. Climatically, this area is slightly drier than the western foothills of the Eastern Tiers. The effective precipitation is very low, mostly under 100 mm, though the variability of that precipitation is similar to the western foothills. The average maximum daily rainfall is fairly low, between 30 and 50 mm, and moderately variable. This is typical for the drier part of the state.

Topographically, these areas are generally either flat or have gentle slopes. The relief index is also generally low to moderate. Domains 346 and 363 form a slight exception to this rule, both have slopes above 10 degrees, and have a relief index between 50 and 65. The profile and cross sectional curvature measures indicate that at a large scale there are ridges and valleys in this landscape, but that few of these form sharp narrow features. Again, domains 346 and 363 form an exception, the former tending to fall within narrow valleys, and the latter tending to form sharp ridges.

These areas include features typical of a variety of lithostructures. The domains have identified typical bedrock landscapes (numbers 88, 132, 140, 206, 223, 310, 346 and 363), landscapes that typically have coarse slope deposits (133 and 142), landscapes indicative of undifferentiated Cainozoic sediments (domains 155, 292, 326 and 342), and Tertiary sediments (63 and 275). In this area, the Cainozoic sediments probably include modern floodplains, river terraces formed during the Tertiary and Quaternary, aeolian sediments that were probably deposited during the last glaciation, and possibly some slope deposits. As would be expected, domains that indicate bedrock landscapes tend to occur on steeper slopes and be indicative of either ridge or valley forms, where those associated with Tertiary or Cainozoic sediments have the lowest slopes and are associated with the bottom of valleys and with aeolian process history. Domains that are indicative of landscapes where basalt may occur tend to have low relief and fall within valleys.

The character of the rivers The Macquarie River was visited in the field, where it briefly flows through the Midlands Boundary mosaic. No distinctive character was noted, probably because of the short distance that the river spends in this mosaic. Possibly smaller streams with a large portion of their catchment in this mosaic would have a distinctive character, but this has not been assessed. The Macquarie Tier mosaic area was not included in field work.

Midlands The character of the landscape The Midlands form a landscape that is distinctive for its lack of variation (at least in terms of the system controls on river development). Just 4 domains cover almost 99 % of the mosaic. This is because, although the lithostructure varies throughout the area, there is remarkably little variation in either topography or climate (remembering that this variation is assessed in the context of the whole state). This area forms part of the floor of the Longford Tertiary Basin. The landscape is of sediments dating from the Tertiary and Quaternary, which form a relatively flat plain. Through this poke low ‘islands’ of bedrock. There is also some basalt that adds some topographic variation to the Tertiary sediments.

99 Chapter 6. Putting the picture together: linking river landscapes and river character

The climate of this area is dry. Effective precipitation is mostly below 100 mm per year, and averages around 60 mm. The maximum daily rainfall is also low, between 30 and 40 mm, and there is only moderate variation in this measure between years.

The topography is strongly related to the lithostructure and process history. Domain 206, which occupies 52 % of the mosaic, represents the bedrock part of the landscape. Basalt, dolerite and Parmeener Supergroup rocks all occur in the area. In the overall flatness of the Midlands, these areas of rock have the steepest slopes (in rare cases up to 14 degree, but more typically around 4 degrees), the highest relief (the relief index goes up as far as 65, although it is usually closer to 30) and the most chance of ridge or valley topography. For comparison, in the Eastern Tiers slopes often were over 20 degrees, and the relief index extended to 160.

Domains 342 and 275 represent the sedimentary component of this landscape. They occupy 44 and 2.2 % of the area of this mosaic respectively. Domain 342 indicates Cainozoic sediments, which probably include modern floodplains, river terraces, and aeolian sediments. Domain 275 reflects areas of Tertiary sediments, which are mostly found close to Tertiary basalt flows that have protected them from erosion. Together, these domains make for a very flat landscape, with slopes almost always under 6 degrees, the relief index almost always under 30, and profile and cross sectional curvature measures indicating neither valleys nor ridges because of the great flatness of the landscape.

The character of the rivers The rivers of this region are for the most part low energy, alluvial systems, that are occasionally influenced by bedrock. Observations of rivers in this mosaic are limited to the Macquarie River, in the 44 river kilometres between entering the Midlands and the confluence with the Elizabeth River. In this distance, there are three different river characters, that reflect the degree to which the river is in equilibrium with its landscape, and the proximity to different landforms within the Midlands. The river character of the Macquarie River is described in more detail in Appendix 9.

The first segment of the Macquarie River in the Midlands mosaic is influenced by the transition onto a very flat and open landscape. As is typically the case in these circumstances, the river forms an alluvial fan. In this segment, the floodplain typically covers the whole of the valley floor, and there are often secondary channels that distribute water during floods. This river character is a response to the decrease in stream power as the river slope and valley confinement both decrease on entering the plain. This alluvial fan has a very low gradient, because it is a response to a relatively small change in stream power. This segment of stream is also influenced by some low basalt hills that border the floodplain. Several sequences of broadwaters and small intervening channels occur in response to the sporadic valley confinement caused by these hills.

The second segment of the Macquarie River reflects the influence of its immediate landscape, rather than the transition from one mosaic to another. It can be described as a partly terrace confined river with planform controlled discontinuous floodplains. Instead of bedrock valley walls, alluvial terraces flank the floodplain. The river generally has low sinuosity.

The third segment of the Macquarie in this landscape is a response to some of the bedrock outcrops that occur throughout the plain. Near Campbell Town, the Macquarie has cut a valley through some of these hills. The result can be described as a low gradient valley controlled river with occasional floodplains. The bedrock valley walls are an important control on the river. The channel again flows through a broadwater sequence, where long, wide and deep pools are interspersed with sections of narrow meandering channel. The pools typically fill the floor of the narrow valley, and the meandering sections occur where the floodplain is widest.

100 Chapter 6. Putting the picture together: linking river landscapes and river character

Figure 55. The Macquarie River at Cassiford Marsh, in the low angle alluvial fan. Note the secondary channels on the floodplain, and the low hills constricting the river.

Figure 56. The Macquarie River in the low slope valley confined reach.

Table 6. River characters observed in the Midlands landscape mosaic. Stream character Context Low angle alluvial fan with Where a decrease in channel slope and valley broadwaters confinement causes a change from moderate to low stream power. Broadwater pools occur where the channel is temporarily confined by valley walls. Partly terrace confined alluvial Occurs in wide alluvial valleys where terraces occupy a river portion of the valley floor. Low slope valley confined Where the valley is relatively narrow amongst bedrock hills, confining floodwaters and restricting movement of the stream channel.

101 Chapter 6. Putting the picture together: linking river landscapes and river character

An overview of the domain mosaics and the system controls on river development and behaviour in the case study area.

This chapter has presented an analysis of the use of river environment domains to identify distinctive river landscapes, and the use of those landscapes to predict river character. It is worth presenting an overview of how well the domain mosaics have defined recognisable river landscapes. It is also important to present an overview of how these subregional landscapes relate to the form and behaviour of rivers within the case study area.

The areas identified by the domain mosaics do represent recognisable landscapes and on the whole these distinctive characters are evident in the component domains. Appendix 6 includes figures showing how the domain mosaic areas relate to the system controls on river development and behaviour (note that with the exception of aeolian processes, the geomorphic process history regions that do not occur in the case study area are not shown). On the whole, it appears that the mosaic areas do correspond to patterns in the underlying system controls. However, two issues arise from this comparison with the system controls. First, it is possible that in places the boundaries have not always fallen in the ideal positions. For example, the boundary between the Eastern Tiers Crest area could perhaps be enlarged to the east and south to include more of the land with low relief, slopes, and curvature measured at a fine scale. Secondly, some mosaic areas appear to very similar to one or more of their neighbours.

This imprecision in the location of mosaic boundaries can be attributed to three sources. Firstly, as described above some domains represent landscapes including a large range of values for some system controls. This means that it is hard to identify small changes in the landscape by using those domains. Secondly, some domains, such as domain 93, cover very large areas and are dominant in more than one domain mosaic. Where a mosaic boundary must be drawn through a large patch of this domain, there is little guidance as to its precise position. Thirdly, to some extent, variations in the scale and quality of the inputs to the EDA appear to have lead to mosaic boundaries which differ from those expected by expert opinion. The distinctive area of the East Draining Uplands consists of steep, high relief valleys that drain from west-east. These features appear to have been formed by steep east draining rivers that have had the power to erode valleys regardless of any structures in the underlying rock. Further west, the Tiers are is characterised by areas of gentle slope and low relief, but it also has some very steep and high relief valleys that run roughly north-south, and appear to be controlled by structures in the dolerite geology. River in these valleys have relatively gentle gradients, and eventually drain westward. Some of this area was identified as the Eastern Tiers Crest, but this area should have been much larger, and included some of the land that was classified as either the eastern or western uplands areas. It appears beyond the ability of the Domain Analysis to detect the subtle topographic differences between valleys controlled by geomorphic history and those controlled by bedrock structures. It seems that we must rely on expert knowledge and judgement to identify these problems and rectify them.

Although some mosaic areas are distinctly different in terms of component domains, they are very similar in terms of the system controls on rivers. Two examples of this are the Pink Mosaics and the West Draining Uplands, and the Apsley and East Draining Lowlands areas. In both cases, the areas are neighbours. The lowlands areas are dominated by single domains, 417 in the case of the eastern lowlands, and 384 in the case of the Apsley lowlands. These domains are very similar to each other, varying chiefly in terms of the magnitude and variability of the average annual maximum daily rainfall. It may be that when the state wide variation in mosaic landscapes is assessed, these areas end up being merged because of their similarity.

102 Chapter 6. Putting the picture together: linking river landscapes and river character

Regardless of these concerns, the domains appear to be a good basis for objectively identifying internally consistent river landscapes throughout the state. It may prove necessary to make some small changes to the final, state wide map, based on expert knowledge of rivers and landscape, however, the boundaries have been left where they are awaiting analysis on a state wide scale, and possible revisions of the Domain Analysis itself.

The relationship between river landscapes and river form and behaviour in the case study area.

The most efficient way to highlight the successes and problems of the landscape mosaics is to consider the relationship between river landscape and river character throughout the case study area. This is shown in Figure 57. The upper Macquarie River is described in more detail in Appendix 9.

Legend Gorge Steep valley confined Low sinuosity gravel bed undifferentiated Swamp forest Valley confined, undifferentiated Cohesive meandering Steep valley confined with Partly confined by terraces with Apsley Uplands occasional floodplains frequent paired floodplains Low gradient valley confined with Estuary undifferentiated occasional floodplains Channelised Cobble and boulder alluvial fans unincised Unclassified river segment Broadwater sequence Mosaic boundary

Pi nk C

Western Uplands Midlands Eastern Uplands Macquarie Tier Apsley Lowlands Bas alt Ba sin Eastern Tiers Crest

Pi nk B

Eastern Lowlands

Western Foothills N

Midlands Boundary Pi nk A Kilometres Eastern Foothills 0510

Figure 57. A comparison of field observations of river character and the domain mosaic areas in the upper Macquarie and Apsley catchments. For the most part, the range of river characters found within any one subregion is appropriate for that landscape, and reflects the effect of different features within the landscape, and differences in catchment size or catchment influence. For example, the three different river characters described on the Macquarie River in the Midlands reflect the influence of the Cainozoic sediments or the low bedrock hills that are found in the area, or are transitional features found where the river first flows into the subregion. Similar explanations can be found for the variety of river characters found in the West Draining Uplands, the Apsley Lowlands and East Draining Lowlands. However, the range of it is not so suitable in the East Draining Uplands, which are characterised by steep narrow valleys and gorges, and yet include a variety of low relief river characters such as the den sequence at Longmarsh on the

103 Chapter 6. Putting the picture together: linking river landscapes and river character

Macquarie River. The cause of this appears to be the poorly located boundary between the Uplands and the Crest of the Eastern Tiers. If the Crest area included the majority of the low relief area in the Tiers, this would include Longmarsh, and leave the Eastern Uplands with the more powerful river characters.

If the boundaries between subregions have been located in the correct places, it would be expected that they would correspond to a major change in river character. Again, this is often the case. The boundary between the Midland Boundary and the Midlands, and between the East Draining Uplands and the Apsley lowlands are examples of cases where the boundary between subregions almost exactly corresponds with a change in river character mapped in the field. However, in some places this is not the case. Once again, the boundary between the Crest of the Eastern Tiers, and the Eastern Draining uplands is an example of this. It is possible that this boundary ought to be far further to the east and south, with the result that all of the Macquarie River would be encompassed in the Crest or West Draining uplands.

We have recognised that some domain mosaics that bear little similarity to each other in terms of component domains are actually very similar in terms of the system controls on rivers. In these cases, it seems that the similarity in landscape is reflected in river character, and very similar river types are found in each. For example, Apsley Lowlands and the East Draining Lowlands are fairly similar landscapes, differing slightly in terms of climate, but very similar in terms of the remaining controls on rivers. As a result, there may be a difference in the character of small streams with catchments that are entirely within one or the other of these domains. However, as these are lowland areas, most of the waterways that pass through them have large catchments in other areas of the landscape, and their hydrology is more to be related to these catchments than the local climate of their downstream most reaches. There is in fact a marked similarity in the character of rivers found in these two areas. The Apsley River immediately downstream of the Apsley Gorge is similar to the Wye River where it leaves the hills; and the broadwaters of the lower Apsley appear to be mirrored on the lower Swan.

Conclusions This chapter has presented an analysis of the use of river environment domains to identify distinctive river landscapes, and the use of those landscapes to predict river character. In the whole this has been a success. There are some problem areas, but it appears that many of these will be resolved when assessed in the context of the statewide patterns in the river environmental domain map. It is possible that in some places, expert judgement will be required to adjust boundaries, but this is a useful tool for producing a draft regionalisation that will need relatively little adjustment.

104 Chapter 7. Field based characterisation and classification of rivers

Chapter 7. Field based characterisation and classification of rivers

Introduction Field based assessment of river geomorphology is the only way to get detailed and accurate information on the present form of the river. In combination with map based data, and historical information such as dating of sediment, use of old maps and aerial photographs, it allows you to develop a characterisation of river form and behaviour. This will: S identify the geomorphic processes that are maintaining the river form, S assess the condition of the river (that is, how its present form compares to its undisturbed state), and S assess how the form and condition of the river are changing. Is the river deteriorating, stable or improving? This information is essential for assessing geoconservation value, assessing the geomorphic hazard posed by a river, and prioritising conservation and management activities in the river.

Field based river characterisation is also a very important component of this project. It provides a means of ground truthing the regionalisation. When the regions are shown to be valid, field assessments are needed to provide the information about river character and behaviour within each region.

River characterisations completed for this project Intensive field assessments of river character were made in three areas the state as a part of this project. These were King Island, the area south of Birches Inlet, and the upper Macquarie Catchment. Many smaller assessments were also made, covering individual reaches rather than big lengths of stream or entire catchments.

As described in Chapter 2, the river styles approach developed by Brierley and others66,67 has become the standard approach to river characterisation in south eastern Australia. This approach has a strong within catchment focus. Also, it focuses on geomorphic units, which are small scale features of the channel and floodplains, to identify river reaches. These features are discussed below. This methodology was not followed closely for the characterisations completed for this project, because the goals of this study related to identifying regional river characters that could be predicted from landscape scale features. Instead the focus was widened in both space and time, to consider landscape scale controls on river form, and how these have varied with climatic changes after the last glacial period. However, at the end of the day, the results are probably reasonably similar.

Detailed descriptions of the King Island, Birches Inlet and upper Macquarie catchment areas and the character of the rivers within them can be found in Appendices 7, 8 and 9. Brief descriptions of smaller characterisations completed during this project can be found in the database presented in Appendix 10.

A comparison of existing characterisations around the state By the end of 2002, geomorphic river characterisations had been completed for part or all of 27 catchments around the state. These studies form an eclectic group, differing widely in terms of purpose, methods, expertise of characteriser, resources available, and length of river assessed. Individually, they are relevant to the management of the catchment they

105 Chapter 7. Field based characterisation and classification of rivers

characterise. Together, they form a potentially valuable resource that can tell us about the variation in river character throughout the state. However, before this potential can be realised, it is necessary to find a common language to express the findings.

The reasons for which these river characterisations were completed vary widely. Most were completed for Rivercare plans or for this project. However, one was completed as part of a Bushcare report, two formed part of environmental flow assessments, three were the basis of assessments of potential environmental impact (of two proposed dams and a Rivercare plan), one was part of an assessment of impact of completed river works, and one was completed as an honours project. The purpose of the assessment determines what aspects of river character are the focus of the work. So, for example, an environmental flows study will pay a lot more attention to small variations in bank erodibility than a Rivercare study. The scale of the assessments also varies enormously, from an individual reach 100’s of meters long, to enormous areas such as entire large catchments, including the trunk stream and all the main tributaries. Similarly, the resources available varied enormously in terms of time and money, and this was not always related to the length of river under consideration. Finally, the expertise of the practitioner varied from geomorphologists with many years experience who had been involved in the development and application of the river styles approach in New South Wales, to others with experience in the general field of river management but limited geomorphic training.

All these characterisations identify river reaches that have relatively consistent form, and either describe and name the individual reach, or attribute the reach to a previously described type of river (river styles in Brierley et al.’s scheme66). If the described river styles adequately covered the range of river characters across the state, and were consistently applied, then a comparison of different studies is simply a matter of comparing where different river styles occur in the studied catchments. However, for a variety of reasons, many of which were described above, the identification of river styles is not consistent across Tasmania. This is also a result of the catchment focus of both the river styles methodology and the funding of catchment characterisations. River style names used in Tasmania tend to focus on describing the difference between a reach and the rest of the catchment, not necessarily on describing the fundamental nature of the reach. This results in a diversity of river styles describing basically very similar reaches. It is notable that the opposite problem also occurs, where a style name is applied to a far broader range of river types than was implied in the original uses of the name, or that is useful for understanding and managing the river.

To reconcile these inconsistencies, we developed a set of names and definitions that could be consistently applied across Tasmania. For ease, these are referred to as Taswide styles. This is a similar exercise to Brierley et al.’s overview of river styles in the north coast catchments of New South Wales.94 We reclassified rivers with Taswide styles to allow the development of a state wide map of river character, and the appreciation of regional patterns of river type. This was done using the descriptions of river character in published reports, reference to 1:25,000 maps and field appearance where one of the authors had some knowledge of the river in question.

It is very important to acknowledge the different roles of the catchment based river characterisation and this state wide analysis. Within a single catchment, a characterisation completed for a specific purpose will often require a finer break down of river form and character than is desirable for a state wide classification, if that classification is to remain practical. The Taswide list of river styles does not replace a catchment scale analysis, because it is designed to serve a different purpose.

106 Chapter 7. Field based characterisation and classification of rivers

The Taswide classification The Taswide styles are an attempt to produce an overarching set of river character descriptions for Tasmania, that will allow investigating regional patterns in river character. They may also be useful as a basis for making future river characterisations in the state more consistent. However, we see this as a draft to promote discussion in the river geomorphology community, rather than a final, definitive list of the river characters in Tasmania. The list is not comprehensive, but reflects the rivers for which published characterisation are available, or that were assessed for this project. Not all reaches of all rivers that have been the subject of characterisations have been assigned to a Taswide style. This is largely because the level of information about the river styles varied enormously between reports. In some cases, a suitable Taswide style did not exist, and in other cases the description of the reach in the source document was insufficiently detailed to allow reclassification. The list and descriptions of Taswide styles, and the classification of rivers into these styles is presented in Appendix 10 as a printed list of Taswide styles, an Access database and an Arcview shapefile.

Because they were based on existing work, most of which follows the river styles methodology of Brierley et al.66,67,94, the Taswide styles also roughly follow the river styles manner of describing and naming types of river. Differences perhaps reflect the difference between the New South Wales and Tasmanian environments. The Tasmanian scheme has a greater focus on the role that non fluvial (river) geomorphic processes can play in controlling the development, form and behaviour of rivers. This is particularly apparent in Tasmania, perhaps because of the recent (in geological terms) history of glacial and periglacial activity that is so much more intense than anywhere on the mainland. For example, this has lead to the recognition that bedrock is not the only form of long term control on rivers. A glacial moraine or periglacial scree can have similar effects on river form.

Brierley and Fryirs state that river styles are identified according to ‘channel geometry (size and shape), channel planform, and the assemblage of geomorphic units in a river reach.’193 However, in practise river styles appear to be named mostly according to the channels relationship to the valley, channel planform, bed material and slope, and to a certain extent these features have also taken a primary role in the identification of river reaches. The implications of this are discussed later.

River reaches were assigned to Taswide styles according to the information that was presented in the reach descriptions in the source documents. The quality and quantity of this information varied greatly between reports. This prompted the development of a two tiered system of characterisation, that allows the level of characterisation to reflect the amount of information available about a given reach. This also has the advantage of hierarchical systems in that it allows different characters to be used to separate styles in different parts of the tree.

The top tier of the Taswide style classification is called the superstyle. Superstyles reflect the major type of control on the form and behaviour of the channel. These relate to the degree of control by either bedrock or other erosion resistant material, alluvium or by the sediment and topography created by some other geomorphic process. The super styles are: S alluvial, S confined (by bedrock or some other erosion resistant material), S partly confined (by bedrock or some other erosion resistant material), S aeolian, S karst, S glacial, S transitional, S very small catchments, and S degraded.

107 Chapter 7. Field based characterisation and classification of rivers

Transitional reaches, moving from one type of control to another are included as a super style as they can otherwise be difficult to characterise. Rather than having a consistent distinctive character, they represent a zone of change from one character to another in response to an abrupt change in the controls on the river. Very small catchments are considered distinctive because they are areas where slope processes struggle for dominance over stream processes, and both can be massively influenced by vegetation. As such, the features seen are typically not purely fluvial. Degraded systems that are so altered that neither their form, nor the geomorphic processes that occur in them in any way resemble pre-European form or processes.

Within the super styles, a further breakdown is made to Taswide styles, at a level that reflects stream character on a scale useful in a state wide analysis. This was done largely on the basis of matching the stream form and character with the Taswide style descriptions (see Appendix 10). However, features that can be used as a rough guide are shown in Table 7. These qualitative criteria vary depending on the super style.

Table 7. Criteria used to help differentiate Taswide styles. Note that this list reflects only the river characters identified in the catchments studied so far, and does not represent a comprehensive list for the state. Small catchment super style slope special character Taswide style low not relevant Small catchment swamps high not relevant Small catchment steep streams moderate not relevant Small catchment moderate gradient low to high altitude blockstream and Small catchment low gradient swamp on block moderate peat streams and organic soils. Confined super style slope degree of resistance of Taswide style sediment boundary storage material any any any Valley confined, undifferentiated high any bedrock or Steep valley confined, undifferentiated equivalent high low bedrock or Gorge (Steep valley confined with very little equivalent stored alluvium) high high bedrock or Steep valley confined with occasional equivalent floodplains low low bedrock or Low gradient valley confined with very little equivalent stored alluvium low high bedrock or Low gradient valley confined with occasional equivalent floodplains low any fluvial terraces Low gradient immobile terrace confined beyond competence of present stream Partly confined super style contact resistance of special Taswide style between boundary character channel and material valley wall any any not relevant Partly confined undifferentiated high bedrock or not relevant Partly confined with valley controlled

108 Chapter 7. Field based characterisation and classification of rivers

equivalent discontinuous floodplains moderate bedrock or not relevant Partly confined valley with frequent paired equivalent (planform controlled) floodplains moderate fluvial terrace not relevant Partly confined by terraces with frequent beyond paired (planform controlled) floodplains competence of present stream high fluvial terrace not relevant Partly confined with terrace controlled beyond discontinuous floodplain competence of present stream low bedrock or bedrock Partly confined with vertical bedrock control equivalent underlying broad valley moderate bedrock or sediment Partly valley confined with very narrow equivalent flooded gorge floodplains moderate any broadwater Broadwater sequence Alluvial super style no of degree of bed and bank Taswide style channels sinuosity material one low gravel Low sinuosity gravel bed one to several low gravel Wandering gravel bed river one high any Meandering undifferentiated one high gravel Meandering gravel bed one high sand Meandering sand bed one high sand Meandering sand bed, terrace confined one high silt and clay Cohesive meandering banks one very high clay Fine grained backwater meandering dominated one high to very peat banks Peat controlled meandering gravel bed high none or not relevant any Intact valley fill discontinuous many not relevant any Swamp Forest Transitional super style landform incision into landform Taswide style alluvial fan unincised Cobble and boulder alluvial fans, unincised alluvial fan incised Cobble and boulder alluvial fans, incised Aeolian super style dune form Taswide style parabolic Parabolic dune controlled parallel Parallel dune controlled Karst super style special character Taswide style calcareous dune spring calcareous dune springs Glacial super style degree of confinement Taswide style confined moraine confined dammed moraine dammed lake alluvial Central plateau floodplain with levees alluvial Central plateau floodplain with tunnels

109 Chapter 7. Field based characterisation and classification of rivers

Estuarine super style influenced by marine processes Taswide style yes Estuary undifferentiated Degraded super style Channelised Massively oversized channel Taswide style yes yes Entrenched in fine sediments yes no Channelised

Limitations of existing river characterisations The existing approaches to river characterisation have several important limitations that become particularly apparent when applied over a large area, but can also hold within a single catchment. These relate to the focus on channel planform and relationship to the valley form in identifying and naming river styles, and the difficulty of establishing geomorphically meaningful boundaries to the river styles.

Under the river styles methodology, styles are in practice named primarily according to the channel’s relationship to the valley and the channel planform, and to a lesser extent bed material and slope. This can be observed from browsing any River Styles Report, such as the Mersey report in Tasmania,87 or one of the many from New South Wales (eg94,194,195). With a few exceptions, the Taswide styles described here also follow this pattern.

There are two shortcomings to this naming approach. Firstly, according to the original river styles methodology,66 river reaches are identified and their style described in terms of their geomorphic units. However, the proliferation of names such as ‘partly confined valley with planform controlled discontinuous floodplain’87 draws attention to the surrogates of planform and relationship to valley walls. It does this at the expense of channel and floodplain features, and also at the expense of other controls on the development of those features such as environmental history, catchment geology, climate, vegetation and upstream catchment form. As a result, there is the potential to ignore a variety of differences in form and behaviour resulting from these influences. It is notable that the partly confined river styles occur on 14 of the 15 lithostructural elements, in almost all climatic zones where characterisations have been completed, and under a range of vegetation types including wet and dry forest, grassland and woodland, rainforest and buttongrass. It is possible that these unacknowledged differences in catchment might not cause important differences in river form or behaviour within a single river style. However, this is as yet untested.

Here again it must be acknowledged that river styles are primarily designed to assess river character within a catchment. It is only in large catchments where the controls on rivers vary significantly, or when multiple catchments are assessed and the comments on river behaviour and management requirements extrapolated that the shortcomings of this approach become apparent. The development of river regions as reported on in Chapter 6 may be an efficient way to overcome this problem. These regions will identify variations in climate, geology, topography and the history of geomorphic processes (although we sadly acknowledge not vegetation at this stage). These regions may help identify systematic variation within river styles, because they describe the varying landscape context of the river style.

Secondly, in order to predict river behaviour, it is necessary that the boundaries between river types are geomorphically meaningful. This is comparatively easy to achieve for river types that are known from the international literature. These are mostly the alluvial river types, such as meandering rivers and wandering gravel bed rivers (eg47,48,196-198). However, for rivers that figure less regularly in the literature, such as those that are partly alluvial and partly controlled by bedrock, less information is available. With these rivers, we are less likely to be

110 Chapter 7. Field based characterisation and classification of rivers able to predict channel behaviour, or to recognise different types of channel from their form. This makes it much harder to identify meaningful river style boundaries, as is required if we are to predict river behaviour.104 There is little that can be done about this in the short term. In terms of our developing understanding of these river types, we are in a data collection phase, describing features and studying the slowly emerging patterns. In the future this part of the characterisation can be reviewed to reflect increasing knowledge.

111

Chapter 8. Conclusions and recommendations

Chapter 8. Conclusions and recommendations

An appreciation of the importance of geomorphology to river management has been growing in Tasmania in recent years. The goals of this project were to aid river management and conservation in Tasmania by providing a context for assessments of conservation value; identification of remnants and template streams, and the basis for the development of regionally specific advice on river management.

In Brierley et al’s 1996 approach to catchment characterisation the authors outline two main themes for management oriented research into river systems.199 S An ecoregional approach which aims to identify and conserve intact or near intact examples of streams and stream segments both for the conservation of biodiversity and to act as templates for river management in less natural systems. S A river restoration imperative which recognises that a large proportion of our rivers are no longer in a natural state and that proper catchment characterisation and assessment of the trajectory of river condition are keys to most effectively managing rivers.

In subsequent work, Brierley and his colleagues have focussed almost exclusively on the second of these aims, however in Tasmania it is readily apparent that this state possesses a large number of streams or stream segments which do in fact remain in an essentially natural condition. Tasmania may in many respects be regarded as a last ‘refuge’ for many of the stream types now permanently degraded in the southeest corner of the mainland. It also possesses a wide variety of stream types found nowhere else in the country.

This project has therefore focussed on the first aim, and its results will now be used as a major input into the Tasmanian Conservation of Freshwater Ecosystem Values project (CFEV). The CFEV project was designed to ensure conservation of a representative range of river types and associated ecosystems from the perspectives of both geoconservation and biological conservation. Elements of both the geodiversity and biodiversity of Tasmanian river systems will be equally represented in the management and reserve system the CFEV project will produce.

At the core of this project is the issue of what aspects of the environment control stream form and stream character, and whether it is possible to predict one from the other. Those controls vary in scale. At one end of the scale are the long term, large scale features that can be mapped on a state wide scale such as lithostructure or climate, that influence the development of the river through long periods of time, and influence the present day form and behaviour. At the other end of the scale are features of the local environment (determined by overall system controls) that can only be described through analysis of large scale aerial photographs and field assessments, such as local valley alignment, the nature of stream sediments, vegetation patterns or bedrock outcrops. These features both influence and reflect the present day form of the river. In all cases, there is also a shifting balance between the influence of the immediate environment, and the influence of the environment of the upstream catchment. The character of the catchment influences the flow of water and sediment that interact with the immediate environment and the history of that environment to produce the character of the reach at that point.

There are also important issues related to lag times from the onset of change in any system control to its expression in the form and behaviour of a river. Similarly, streams may become ‘fossilised’, that is competent, long-lived streambank vegetation such as Huon Pine may trap the river in a form essentially related to past environmental controls no longer operating.

113 Chapter 8. Conclusions and recommendations

So, the controls on river form and behaviour are both local, regional and time transgressive. Because of this, assessments of river character at all relevant scales are valuable. Field assessments are the best way to develop reliable descriptions of present river form, condition, and potential behaviour. However, so long as river managers try to extrapolate their experience from one catchment to another, and so long as decisions about conservation value and resource use are made on a scale greater than a single catchment, then a regional classification is also important. One conclusion from this work is that while valuable information can be gained from either type of study, the most useful information comes from a synthesis of the two. Either one, without the other, gives only a partial picture of the river.

This project has developed a method for defining geomorphic river regions on a state wide scale based on system controls, the regional influences on river development and form. We have gone a good deal of the way towards completing that task. When complete, this map must be subject to ongoing testing against field characterisations.

As with all large scale projects like this one, it is likely to take many years of incorporating the results of catchment characterisations to produce a final product. This testing process has begun in this project, by comparing the streams of the Eastern Tiers to the assessment of sub regional boundaries. The area does confirm the general accuracy of the river Environmental Domain Analysis. However, it has also identified several ways in which the analysis could be improved (see chapters 5 and 6). These are summarised in the Recommendations section below. The eventual result of such efforts to refine this work will be an accurate picture of the diversity of Tasmania’s river landscape, and a solid basis for identifying regional patterns in river behaviour. As it is, the present analysis does appear to be a useful way of looking at the variation in river landscapes across the state. It is a tool that reduces the huge and complex variation in the controls on river development and behaviour around the state to a manageable level, and so allows variation in landscape at any one place to be considered in the context of the whole state.

The work on field based characterisation of rivers consisted of two parts. Firstly, field assessments of river character on King Island, the Birchs Inlet area and the upper Macquarie River catchment are included in the appendices of this report. Secondly, we have compared all assessments of geomorphic river character completed before the end of 2002. These reports are diverse in their purpose and style. Generally, they provide good descriptions of river form, and sound assessments of river character within the catchment. However, there are two areas where there is room for improvement.

The quantity of information on reach geomorphology did vary between reports, and was not always adequate for the uses of that report. A good rule of thumb is that descriptions of each river reach should be sufficient to justify the predictions of river character. Relying instead on reference to river characters found in other catchments should be avoided, especially if a reason to expect similar river character in the two catchments has not been demonstrated.

This raises the second area of concern with field based catchment characterisations, which is that this work is catchment based, and seldom includes any reference to features outside a single catchment. River reaches are identified and described with reference to the variation in river form within a single catchment, often with an emphasis on valley alignment. This is usually sufficient to identify and characterise river reaches within a catchment. However, it does make the comparison of different catchments difficult. It is notable that similar names are given to reaches of different character in different catchments, and that very similar reaches are given quite different names. This is not just an academic concern. The ability to compare work in different catchments is very important if river managers are to be able to extrapolate information and experience from one area to another. Regardless of the intentions of the authors, this is likely to occur and can be an excellent source of information, so long as the extrapolation is acceptable. Also, assessments of river conservation value are often

114 Chapter 8. Conclusions and recommendations required on scales greater than a single catchment. We acknowledge that these state wide goals have not been included in the consultants briefs for this river characterisation work. However, to make no attempt at consistent naming and descriptions of river character is to miss an opportunity to develop an easily compatible database of rivers throughout the state, that can be used to improve both river management for conservation and utilitarian purposes

This report has come up with two proposals to increase the consistency of river character naming throughout the state. Firstly, we have proposed an overarching set of river character descriptions for Tasmania (Appendix 10). This list is not intended to be comprehensive, but reflects the existing characterisation work. Also, it is not intended to be a final document, but rather a draft to promote discussion in the river geomorphology community within the state. Secondly, we strongly recommend that future river characterisation work should be couched within the context provided by the river regions (when complete). These regions will identify variations in climate, geology, topography and the history of geomorphic processes across the state. They will describe the landscape context of the river character, and therefore separate similarly named river styles into distinct regionally meaningful types.

Recommendations 1. The recent effort that has been put into using river geomorphology as a source of information for river management, both for nature conservation and utilitarian goals should continue. 2. The regionalisation of river geomorphology should be completed as soon as possible. 3. To understand and predict river behaviour across the state requires good quality base data. Efforts should be made to map (based on field surveys or GIS modelling) the following variables. These will be valuable not just for developing a river region map, but also as a source of information for land managers in general. The following should be mapped. S Modern river sediments (ie floodplains) have a huge influence on river form, and the potential for the river to adjust that form through erosion of its bed and banks. The distribution of these sediments should be mapped and modelled, then included as a system control in the Environmental Domain Analysis. S Coarse slope deposits resulting from intense periglacial activity during the last glacial maximum have a huge influence on small steep streams that occur on them. The distribution of these deposits should be mapped and modelled, then included in the Environmental Domain Analysis as a system control on rivers. S Geological process regions (eg uplifted erosion surfaces and active faults). 4. The Environmental Domain Analysis that is the basis for the river region map should be improved in the ways described in the conclusion. S Use of any new data referred to above. S Use of a smaller grid in the Digital Elevation Model used to calculate the topographic variables and to perform the environmental domain analysis. A 25 m grid would be ideal. This would generate far smoother topographic data at fine scales, and so represent the environment more faithfully. It would also allow the shape of domains to follow the underlying landscape more closely. S The Karst process region could easily be improved using the most recent version of the Karst Atlas mapping. S The Aeolian process region should be divided into areas active under the present climate (almost exclusively coastal areas), and areas active during the last glacial maximum (includes inland sand sheets and dune fields). S Further investigation of mapping the effect of natural vegetation on river development and using it as a system control where relevant. S When defining domains, allow small patches (less than 4 pixels) that are not similar to any neighbouring patches to remain unattached to any domain.

115 Chapter 8. Conclusions and recommendations

S Experiment with weighting the input data, and using fuzzy boundaries to represent uncertainty in the mapping, to see if you get domains that more faithfully follow lines of local similarity in the landscape. 5. Greater effort should be put into making field based characterisations of river geomorphology consistent across the state. This should in part be achieved by couching assessments of river character within the context provided by river regions, when complete. 6. The Taswide river character should be discussed in the Tasmanian river geomorphology community, improved and adopted as a flexible basis for consistently naming river characters throughout the state. 7. When complete, the interim river regions map will still require considerable testing against field data. This process, and the regular updating of the regions to reflect our growing knowledge of Tasmania’s river systems is of great importance and should continue.

116 References cited

References cited

1. Rutherfurd, I., 2000. Some human impacts on Australian stream channel morphology. In Brizga, S. & Finlayson, B. (eds.), River Management: the Australasian Experience. John Wiley & Sons, pp. 11-49. 2. State of the Environment Unit, 1996. State of the Environment Tasmania. Volume 1 Conditions and Trends. Department of Environment and Land Management, Hobart 3. DPIWE, 2002. Water Development Plan for Tasmania. Department of Primary Industries, Water and Environment, Hobart 4. White, L. J., Rutherfurd, I. D. & Hardie, R. E., 1999. On the cost of stream management and rehabilitation in Australia. In Rutherfurd, I. D. & Bartley, R. (eds.), Second Australian Stream Management Conference, Adelaide. Cooperative Research Centre for Catchment Hydrology, pp. 697-703. 5. Commonwealth of Australia, 1999. Australian Guidelines for Establishing the National Reserve System. Environment Australia, Canberra 6. Dunn, H., 1999. Identifying and protecting rivers of high ecological value. Final Report LWRRDC Project #UTC 1. University of Tasmania, Hobart 7. Environment Australia, 1998. Conservation guidelines for the management of wild river values. Environment Australia, Canberra 8. Rutherfurd, I. D., Jerie, K. & Marsh, N., 1999. A rehabilitation manual for Australian streams, Volume 1. LWRRDC, Melbourne. 9. Rutherfurd, I. D., Jerie, K. & Marsh, N., 1999. A rehabilitation manual for Australian streams, Volume 2. LWRRDC, Melbourne. 10. Peters, D. & Thackway, R., 1998. A new biogeographic regionalisation for Tasmania. Tasmanian Parks and Wildlife GIS Section, Hobart 11. Houshold, I., Sharples, C., Dixon, G. & Duhig, N., 1997. Georegionalisation - a more systematic approach for the identification of places of geoconservation significance. In Eberhard, R. (ed.) Pattern and Process. Toward a regional approach to National Estate Assessment of Geodiversity, Australian Heritage Commission. Environment Australia. 12. Bailey, R. G., 1988. Problems with using overlay mapping for planning and their implications for geographic information systems. Environmental Management 12(1): 11-17. 13. DPIWE, 2000. Tasmanian shoreline geomorphic types GIS data set. Version 1. Department of Primary Industries, Water and Environment, Hobart 14. Corbett, C., Dudley, A., Sainty, R., Stanton, S., Sharples, C. & Warman, R., 1999. Wild rivers management pilot project Tasmania. Tasmanian Department of Primary Industries, Water and Environment. 15. Dixon, G. & Duhig, N., 1996. National Estate Values (Geoconservation). Compilation and assessment of some places of geoconservation significance. Final Draft. Tasmanian RFA Environment and Heritage Technical Committee, Hobart 16. Sharples, C., 1995. Geoconservation in forest management - principles and procedures. Tasforests 7: 37-50. 17. Sharples, C., 2002. Concepts and principles of geoconservation. http://www.dpiwe.tas.gov.au/inter.nsf/Attachments/SJON- 57W3YM/$FILE/geoconservation.pdf. Tasmanian Parks and Wildlife Service, Last updated September 2002, Accessed 5/3/03 18. Houshold, I. & Jerie, K., 2001. Report on the geomorphology of the lower Welcome River and comments on the Welcome River Rivercare Plan. Unpublished internal report. Earth Science Section, DPIWE, Hobart 19. PWS, 1994. Tasmanian Parks and Wildlife Service reserve system categories, definitions and primary objectives. Parks and Wildlife Service, Tasmania, Hobart

117 References cited

20. DPIWE, 2003. Tasmania's Nature Conservation Strategy. Department of Primary Industries, Water and Environment, Hobart 21. Forest Practices Board, 2000. Forest Practices Code. Forest Practices Board, Hobart, Tasmania. 22. Dixon, G., Sharples, C., Houshold, I., Pemberton, M. & Eberhard, R., 1997. Conservation management guidelines for geodiversity. Tasmanian RFA Environment and Heritage Committee, Hobart 23. DPIWE, 2001. Tasmanian Geoconservation Database. Department of Primary Industries, Water and Environment, Last updated 2001, Accessed 24. Kiernan, K., 1995. An atlas of Tasmanian karst. Volume 1. Research Report 10. Tasmanian Forest Research Council, Hobart 25. Kiernan, K., 1995. An atlas of Tasmanian karst. Volume 2. Research Report 10. Tasmanian Forest Research Council, Hobart 26. Forest Practices Board, 1999. Some operational considerations in sinkhole management. Forest Practices Board, Hobart 27. Kiernan, K., 1996. Conserving geodiversity and geoheritage: the conservation of glacial landforms. Forest Practices Unit, Hobart 28. Wells, F., 2002. Classification and risk assessment of headwater streams to improve stream management in the forestry estate of Tasmania. Forest Practices Board and FIAT/FT Research Fund, Hobart 29. Brussock, P. P., Brown, A. V. & Dixon, J. C., 1985. Channel form and stream ecosystem models. Water Resources Bulletin 21(5): 859-866. 30. Barmuta, L. A., 1989. Habitat patchiness and macrobenthic community structure in an upland stream in temperate Victoria, Australia. Freshwater Biology 21: 223-236. 31. Brussock, P. B. & Brown, A. V., 1991. Riffle-pool geomorphology disrupts longitudinal patterns of stream benthos. Hydrobiologia 220: 109-117. 32. Huryn, D. H. & Wallace, J. B., 1987. Local geomorphology as a determinant of macrofaunal production in a mountain stream. Ecology 68(6): 1932-1942. 33. Brown, A. V. & Brussock, P. P., 1991. Comparisons of benthic invertebrates between riffles and pools. Hydrobiologia 220: 99-108. 34. Statzner, B. & Higler, B., 1986. Stream hydraulics as a major determinant of benthic invertebrate zonation patterns. Freshwater Biology 16: 127-139. 35. Coleman, R. L. & Dahm, C. N., 1990. Stream geomorphology: effects on periphyton standing crop and primary production. Journal of the North American Benthological Society 9(4): 293-302. 36. Omernik, J. M., 1995. Ecoregions: A spatial framework for environmental management. In Davis, W. S. & Simon, T. P. (eds.), Biological Assessment and Criteria. Tools for water resource planning and decision making. Lewis Publishers, Florida, USA, pp. 49-62. 37. Omernik, J. M., 1987. Ecoregions of the conterminous United States. Annals of the Association of American Geographers 77(1): 118-125. 38. Cox, C. B. & Moore, P. D., 1985. Biogeography. A ecological and evolutionary approach. Blackwell Scientific Publications, London. 39. Gore, J. A., 1978. A technique for predicting in-stream flow requirements of benthic macroinvertebrates. Freshwater Biology 8: 141-151. 40. Newall, P. & Wells, F., 2000. Potential for delineating indicator-defined regions for stream in Victoria, Australia. Journal of the North American Benthological Society 19(3): 557-571. 41. Erskine, W. D., 2001. Geomorphic evaluation of past river rehabilitation works on the Williams River, New South Wales. Ecological Management & Restoration 2(2): 116-128. 42. Outhet, D., Adamson, G., Armstrong, J., Graice, J., Hader, W., Lorimer-Ward, K., Massey, C., Nagel, F., Pengelly, S., Raine, A., Shepheard, M., Smith, T., Wem, P. & Young, R., 1999. Evolution of stream protection and rehabilitation in NSW. In Rutherfurd, I. D. & Bartley, R. (eds.), Second Australian Stream Management

118 References cited

Conference, Adelaide. Cooperative Research Centre for Catchment Hydrology, pp. 487-492. 43. Stewardson, M., Rutherfurd, I. D. & Tennant, W., 1999. Physical evaluation of rehabilitation works in Broken River and Ryans Creek, north east Victoria. In Rutherfurd, I. & Bartley, R. (eds.), Second Australian Stream Management Conference, Adelaide, South Australia. Cooperative Research Centre for Catchment Hydrology, pp. 595-600. 44. Gippel, C. J., 2001. Geomorphic issues associated with environmental flow assessment in alluvial non-tidal rivers. Australian Journal of Water Resources 5(1): 3-14. 45. Thoms, M. C. & Sheldon, F., 2002. An ecosystem approach for determining environmental water allocations in Australian dryland river systems: the role of geomorphology. Geomorphology 47: 153-168. 46. Brookes, A. & Sear, D. A., 1996. Geomorphological principles for restoring channels. In Brookes, A. & Shields, F. D. (eds.), River channel restoration. Guiding principles for sustainable projects. John Wiley & Sons, Chichester, pp. 75-102. 47. Church, M., 1983. Pattern of instability in a wandering gravel bed channel. In Collinson, J. D. & Lewin, J. (eds.), Modern and ancient fluvial systems, 6. Blackwell Scientific, Oxford, UK, pp. 169-180. 48. Carson, M. A., 1984. Observations on the meandering-braided river transition, the Canterbury Plains, New Zealand: Part two. New Zealand Geographer 40: 89-99. 49. Jerie, K. & Houshold, I., 2002. The geomorphic context for intervention in rivers. In Dunn, H. (ed.) Instream structures and improving instream habitat workshop, Launceston. Rivercare Tasmania, pp. 5-18. 50. Locher, H., Telfer, D. & Bresnehan, S., 2002. Downstream Meander Dam fluvial geomorphology assessment. Final Report. Hydro Tasmania & GECO Stream & Catchment Assessments, Hobart 51. Gurnell, A. M., Angold, P. & Gregory, K. J., 1994. Classification of river corridors: issues to be addressed in developing an operational methodology. Aquatic Conservation: Marine and Freshwater Ecosystems 4: 219-231. 52. Downs, P. W., 1995. River channel classification for channel management purposes. In Gurnell, A. & Petts, G. (eds.), Changing river channels. John Wiley & Sons, Chichester, UK, pp. 346-365. 53. Naiman, R. J., Lonzarich, D. G., Beechie, T. J. & Ralph, S. C., 1992. General principles of classification and the assessment of conservation potential in rivers. In Boon, P. J., Calow, P. & G.E., P. (eds.), River conservation and management. John Wiley & Sons, Chichester, UK, pp. 93-123. 54. Mosley, M. P., 1987. The classification and characterization of rivers. In Richards, K. (ed.), River channels: environment and process. Basil Blackwell, Oxford, pp. 295-320. 55. Nanson, G. C. & Croke, J. C., 1992. A genetic classification of floodplains. Geomorphology 4: 459-486. 56. Wright, R. L., 1972. Principles in a geomorphological approach to land classification. Zeitschrift fur Geomorphologie 16(4): 351-373. 57. Roux, D., de Moor, F., Cambray, J. & Barber-James, H., 2002. Use of landscape- level river signatures in conservation planning: a South African case study. Conservation Ecology 6(2): Article 6 [online] URK: http://www.consecol.org/vol6/iss2/art6. 58. Snelder, T., Weatherhead, M., O'Brien, R., Shankar, U., Biggs, B. & Mosley, P., 1999. Further development and classification of a GIS based river environment classification system. National Institute of Water and Atmospheric Research, Christchurch 59. Hughes, J. M. R. & James, B., 1989. A hydrological regionalization of streams in Victoria, Australia, with implications for stream ecology. Australian Journal of Marine and Freshwater Research 40: 303-326.

119 References cited

60. Wells, F. & Newall, P., 1997. An examination of an aquatic ecoregion protocol for Australia. Australian and New Zealand Environment and Conservation Council, Melbourne 61. Frissell, C. A., Liss, W., Warren, C. E. & M.D., H., 1986. A Hierarchical Framework for Stream Habitat Classification: Viewing Streams in a Watershed Context. Environmental Management 10(2): 199-214. 62. Thomson, J. R., Taylor, M. P., Fryirs, K. A. & Brierley, G. J., 2001. A geomorphic framework for river characterization and habitat assessment. Aquatic Conservation: Marine and Freshwater Ecosystems 11: 373-389. 63. Wright, J. F., 1995. Development and use of a system for predicting the macroinvertebrate fauna in flowing waters. Australian Journal of Ecology 20(1): 181-198. 64. Hughes, J. M. R., 1987. Hydrological characteristics and classification of Tasmanian rivers. Australian Geographical Studies 25: 61-82. 65. Hine, D. & Graham, B., 2003. A regionalisation of Tasmanian catchments Technical Report WRA 03/02. Department of Primary Industries, Water and Environment, Tasmania, Hobart 66. Brierley, G., Fryirs, K. & Cohen, T., 1996. Geomorphology & river ecology in southeastern Australia: an approach to catchment characterisation. Part One: A geomorphic approach to catchment characterisation. Working paper 9603. Graduate School of the Environment, Macquarie University, Sydney 67. Brierley, G. J. & Fryirs, K., 2000. River Styles, a geomorphic approach to catchment characteriszation: implications for river rehabilitation in Bega Catchment, New South Wales, Australia. Environmental Management 25(6): 661-679. 68. Schumm, S. A., 1991. To interpret the earth: ten ways to be wrong. Cambridge University Press, Cambridge. 69. page 297 in Miller, J. R. & Ritter, J. B., 1996. An examination of the Rosgen classification of natural rivers. Catena 27: 295-299. 70. Erskine, W. & Bell, F. C., 1982. Rainfall, floods and river channel changes in the upper Hunter. Australian Geographic Studies 20: 183-196. 71. Soutberg, T. L., 1990. Towards a descriptive geomorphic classification system for nature conservation purposes. Occasional Paper No. 23. Department of Parks, Wildlife and Heritage Tasmania, Hobart 72. Rosgen, D. L., 1996. A classification of natural rivers: reply to the comments by J.R. Miller and J.B. Ritter. Catena 27: 301-307. 73. Prosser, I. P. & Winchester, S. J., 1996. History and processes of gully initiation and development in eastern Australia. Zeitschrift für Geomorphologie 105: 91-109. 74. Kellerhals, R., Church, M. & Bray, D. I., 1976. Classification and analysis of river processes. Journal of the Hydraulics Division, ASCE 102(HY7): 813-829. 75. Leopold, L. B., Wolman, M. G. & Miller, J. P., 1964. Fluvial processes in geomorphology. W.H.Freeman and Company, San Fransisco. 76. Mollard in Church, M., 1996. Channel morphology and typology. In Petts, G. & Calow, P. (eds.), River flows and channel forms. Selected extracts from the rivers handbook. Blackwell Science, Oxford, UK, pp. 185-202. 77. Nanson, G. C. & Knighton, A. D., 1996. Anabranching rivers: their cause, character and classification. Earth Surface Processes and Landforms 21: 217-239. 78. Montgomery, D. R. & Buffington, J. M., 1997. Channel-reach morphology in mountain drainage basins. Geological Society of America Bulletin 109(5): 596-611. 79. page 311 in Mosley, M. P., 1987. The classification and characterization of rivers. In Richards, K. (ed.), River channels: environment and process. Basil Blackwell, Oxford, pp. 295-320. 80. Clark, M. J., Sear, D. A., Hill, C. T., Branson, J., Newson, M. D., Pawson, R. & Juggins, S., 1999. River channel typology: feasibility for use in river management. Technical Report W87. Environment Agency, Bristol

120 References cited

81. Newson, M. D., Clark, M. J., Sear, D. A. & Brookes, A., 1998. The geomorphological basis for classifying rivers. Aquatic Conservation: Marine and Freshwater Ecosystems 8: 415-430. 82. Mosley, P., 1999. Appendix 5. Review of channel morphology classification. In Snelder, T., Weatherhead, M., O'Brien, R., Shankar, U., Biggs, B. & Mosley, P. (eds.), Further development and classification of a GIS based river environment classification system. National Institute of Water and Atmospheric Research, Christchurch, pp. 43-65. 83. Galay, V. J., Kellerhals, R. & Bray, D. I., 1973. Diversity of river types in Canada. Proceedings of Hydrology Symposium 9: 217-250. 84. Heritage, G. L., Charlton, M. E. & O'Regan, S., 2001. Morphological classification of fluvial environments: an investigation of the continuum of channel types. The Journal of Geology 109: 21-33. 85. van Niekerk, A. W., Heritage, G. L. & Moon, B. P., 1995. River classification for management; the geomorphology of the Sabie River in the eastern Transvaal. South African Geographical Journal 77(2): 68-76. 86. Heritage, G. L., van Niekerk, A. W. & Moon, B. P., 1997. A comprehensive hierarchical river classification system. In Beckedahl, H. R. & Seuffert, O. (eds.), Human impact; geomorphic response. Conference on geomorphic responses to environmental change; the threats and challenges, Pietermaritzburg, Federal Republic of Germany, 1994. Geooeko-Verl., pp. 75-84. 87. Lampert, G., 2000. River StylesTM report, North West Tasmania. Mersey Catchment. Macquarie University for the Mersey Catchment Steering Committee and DPIWE, Sydney 88. Telfer, D., 2001. Snug Rivercare action plan. A report on the future management needs of the Snug River. GECO Stream and Catchment Assessments for Kinsborough North West Bay Progress Association, Hobart 89. Sprod, D., Ketelaar, A. & Armstrong, D., 2000. Mersey River Draft Rivercare Plan. Prepared for the Mersey Catchment Steering Committee 90. Sprod, D., 2001. Rivercare Plan: Orielton Rivulet, Sorrell Rivulet, Iron Creek. Pitt Water Catchment Implementation Committee, Sorell Council, Sorell 91. Telfer, D., 2001. North West Bay River Assessment. A report on the geomorphology and future management needs of the North West Bay River. GECO Stream and Catchment Assessments for the North West Bay River Catchment Management Committee, Hobart 92. Stronach, P., 2001. An assessment of river styles in the Duck River catchment, far NW Tasmania. Honours Thesis, University of Tasmania, Launceston. 93. Morgan, H., Cale, P. & Cunial, S., 2002. St. Patricks River Planning Kit. Rivercare, DPIWE, Launceston 94. Brierley, G. J., Ferguson, R. J., Lampert, G., Cohen, T., Fryirs, K., Reinfelds, I., Goldrick, G., Crighton, P., Batten, P. & Jansen, J., 1999. Summary overview of River StylesTM in North coast catchments of New South Wales. Macquarie Research, Sydney 95. Lotspeich, F. B., 1980. Watersheds as the basic ecosystem: this conceptual framework provides a basis for a natural classification system. Water Resources Bulletin 16(4): 581-586. 96. page 1156 in Jensen, M. E., Goodman, I. A., Bourgeron, P. S., Poff, N. L. & Brewer, C. K., 2001. Effectiveness of biophysical criteria in the hierarchical classification of drainage basins. Journal of the American Water Resources Association 37(5): 1155- 1167. 97. Whiting, P. J. & Bradley, J. B., 1993. A process-based classification system for headwater streams. Earth Surface Processes and Landforms 18: 603-612. 98. Davis, W. M., 1899. The geographical cycle. Geographical Journal 14: 481-504. 99. Gordon, N. D., McMahon, T. A. & Finlayson, B. L., 1992. Stream hydrology. An introduction for ecologists. John Wiley & Sons, Chichester, UK.

121 References cited

100. Schumm, S. A., 1977. The Fluvial System. John Wiley & Sons, New York. 101. Church, M., 1996. Channel morphology and typology. In Petts, G. & Calow, P. (eds.), River flows and channel forms. Selected extracts from the rivers handbook. Blackwell Science, Oxford, UK, pp. 185-202. 102. Nevins 1965 in Mosley, M. P., 1987. The classification and characterization of rivers. In Richards, K. (ed.), River channels: environment and process. Basil Blackwell, Oxford, pp. 295-320. 103. Rosgen, D., 1996. Applied River Morphology. Wildland Hydrology, Pagosa Springs, Colorado USA. 104. Miller, J. R. & Ritter, J. B., 1996. An examination of the Rosgen classification of natural rivers. Catena 27: 295-299. 105. Dixon, G., 1997. A preliminary survey of the distribution and conservation significance of inland aeolian features in the Midlands, Northeast and Southeast Tasmania. Parks and Wildlife Service Tasmania, Hobart 106. Edgar, G. J., Barrett, N. S. & Graddon, D. J., 1998. A classification of Tasmanian estuaries and assessment of their conservation significance: an analysis using ecological and physical attributes, population and land use. Ocean Rescue 2000 - Marine Protected Area Program Regional Classification of Tasmanian Coastal Waters - Stage 2, Estuaries. Department of Environment and Land Management, Tasmania, Hobart 107. Houshold, I., 1999. Appendix 1. Fluvial geomorphology of the Lake River system. In Woolley, A. (ed.), Riparian vegetation and bank condition along a section of the Lake River in Northern Tasmania. Bushcare, Hobart, pp. 55-69. 108. Kiernan, K., 1997. Conserving Tasmania's geodiversity and geoheritage: The conservation of landforms of coastal origin. Forest Practices Board, Hobart 109. Kiernan, K., 1990. Geomorphology Manual. Forest Practices Unit, Hobart 110. Duhig, N., Sharples, C. & Pemberton, J., 1996. Comprehensive Regional Assessment 1:500,000 Lithostructural Elements Map. Tasmania Development and Resources, Hobart 111. Kirkpatrick, J. B. & Dickinson, K. J. M., 1984. Tasmania : vegetation map. Forestry Commission, Hobart 112. Pinkard, G. J. & Richley, L. R., 1984. Land Systems of Tasmania Region 2. Department of Agriculture, Hobart 113. Richley, L. R., 1984. Land Systems of Tasmania Region 1. Department of Agriculture, Hobart 114. Jennings, J. N., 1959. The coastal geomorphology of King Island, Bass Strait, in relation to changes in the relative level of land and sea. Records of the Queen Victoria Museum, Launceston 11: 1-37. 115. Wang, Q. J., McConachy, F. L. N., Chiew, F. H. S., James, R., de Hoedt, G. C. & Wright, W. J., 2001. Climatic Atlas of Australia Maps of Evapotranspiration. Bureau of Meteorology, Last updated Accessed 2001 116. Wood, J., 1996. The geomorphological characterisation of digital elevation models. PhD Thesis, University of Leicester, Leicester, UK. 117. Davies, J. L., 1965. Atlas of Tasmania. Lands and Surveys Department, Tasmania, Hobart. 118. Nevins, T. H. F., 1965. River classification with particular reference to New Zealand. Proceedings of the fourth New Zealand Geography Conference, Dunedin, pp. 83-90. 119. Sharples, C., 2000. Data dictionary for the Tasmanian Shoreline Geomorphic Types GIS dataset version 1. DPIWE, Hobart 120. Burrett, C. F. & Martin, E. L. (eds.) Geology and mineral resources of Tasmania Geological Society of Australia, Hobart, 1989. 121. Fish, G. J. & Yaxley, M. L., 1966. Behind the Scenery. The geological background to Tasmanian landforms. Education Department, Tasmania. 122. Scanlon, A. P., Fish, G. J. & Yaxely, M. L., 1990. Behind the scenery. Department of Education and the Arts, Tasmania, Hobart.

122 References cited

123. Sharples, C., 1994. A reconnaissance of landforms and geological sites of geoconservation significance in north-eastern Tasmanian forest districts. Volume Two - Description. Forestry Tasmania, Hobart 124. Sharples, C., 1994. Landforms and geological sites of geoconservation significance in the Huon forest district. Volume Two - Description. Forestry Commission, Tasmania, Hobart 125. Sharples, C., 1996. A reconnaissance of landforms and geological sites of geoconservation significance in the Circular Head Forest District. Volume Two - Description. Forestry Tasmania, Hobart 126. Sharples, C., 1996. A reconnaissance of landforms and geological sites of geoconservation significance in the state forests of eastern Tasmania (parts of Derwent and Eastern Tiers Forest Districts). Volume Two - Description. Forestry Tasmania, Hobart 127. Sharples, C., 1996. A reconnaissance of landforms and geological sites of geoconservation significance in the Murchison Forest District. Volume Two - Description. Forestry Tasmania, Hobart 128. Sharples, C., 1997. A reconnaissance of landforms and geological sites of geoconservation significance in the Western Derwent Forest District. Forestry Tasmania, Hobart 129. Jennings, J. N., 1957. Coastal dune lakes as exemplified from King Island, Tasmania. The Geographic Journal CXXIII: 59-70. 130. Murray-Wallace, C. V. & Belperio, A. P., 1991. The last interglacial shoreline in Australia - a review. Quaternary Science Reviews 10: 441-461. 131. Murray-Wallace, C. V. & Geode, A., 1991. Aminostratigraphy and electron spin resonance studies of late Quaternary sea level change and coastal neotectonics in Tasmania, Australia. Zeitschrift für Geomorphologie 35(2): 129-149. 132. Caine, N., 1983. The mountains of northeastern Tasmania. A.A.Balkema, Rotterdam. 133. Kiernan, K., 2001. How big is your catchment? Forest Practices News 3: 14-16. 134. Personal communication from Chris Sharples, 135. Sharples, C., 2002. Reconnaissance mapping of soil parent materials in the East Florentine and Upper Tyenna Valleys. Forestry Tasmania (Derwent District), Hobart 136. Ollier, C. D., 1991. Aspects of silcrete formation in Australia. Zeitschrift für Geomorphologie 35(2): 151-163. 137. Taylor, G. & Ruxton, B. P., 1987. A duricrust catena in South-eastern Australia. Zeitschrift für Geomorphologie 31(4): 385-410. 138. Knighton, A. D., 1987. Tin mining and sediment supply to the Ringarooma River, Tasmania, 1875-1979. Australian Geographic Studies 25: 83-97. 139. Nicolls, K. D., 1960. Erosion surfaces, river terraces, and river capture in the Launceston Tertiary Basin. Papers and Proceedings of the Royal Society of Tasmania 94: 1-12. 140. Sharples, C., 1996. The geology and landforms of northeast Tasmania. Records of the Queen Victoria Museum and Art Gallery 103: 55-64. 141. Richley, L. R., 1978. Land Systems of Tasmania Region 3. Tasmanian Department of Agriculture, Hobart 142. Grant, J. C., Laffan, M. D., Hill, R. B. & Neilsen, W. A., 1995. Forest soils of Tasmania. A handbook for identification and management. Forestry Tasmania, Launceston. 143. Pemberton, M., 1989. Land systems of Tasmania. Region 7: South West. Department of Agriculture, Tasmania, Hobart 144. Koehnken, L., Locher, H. & Rutherfurd, I., 2001. Appendix 4. Gordon River Fluvial Geomorphology Assessment. In Locher, H. (ed.), Basslink integrated impact statement. Potential effects of changes to hydropower generation. Hydro Tasmania, Hobart, pp. 279.

123 References cited

145. Abernethy, B. & Bresnehan, S., 2001. Appendix 17. Downstream Poatina geomorphology assessment. In Locher, H. (ed.), Basslink integated impact statement. Potential effects of changes to hydropower generation. Hydro Tasmania, Hobart, pp. 77. 146. Knighton, A. D., 1988. The impact of the Parangana Dam on the River Mersey, Tasmania. Geomorphology 1: 221-237. 147. Wells, F., 2002. Fluvial geomorphological assessment of the Lower Coal River, Hobart 148. Telfer, D., 2002. Fluvial geomorphological assessment of the Lower Derwent River, including a preliminary assessment of the effects of flow regulation. In Davies, P., Warfe, D., Parslow, J. & Telfer, D. (eds.), Environmental flows for the Lower Derwent River: Final report to DPIWE. Freshwater Systems, CSIRO Division of Fisheries and Oceanography, GECO Consulting, Hobart, pp. 21-52. 149. Knighton, A. D., 1987. Streamflow characteristics of northeastern Tasmania: II. Hydraulic geometry. Papers and Proceedings of the Royal Society of Tasmania 121: 125-135. 150. Knighton, A. D., 1987. Streamflow characteristics of northeastern Tasmania: I. Regional flood flows. Papers and Proceedings of the Royal Society of Tasmania 121: 23-33. 151. Folland, C. K., Karl, T. R., Christy, J. R., Clarke, R. A., Gruza, G. V., Jousel, J., Mann, M. E., Oerlemans, J., Salinger, M. J. & Wang, S.-W., 2001. Observed climate variability and change. In Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., Maskell, K. & Johnson, C. A. (eds.), Climate change 2001: The scientific basis. Cambridge University Press, pp. 99-182. 152. Shepherd, D. J., 1995. Some characteristics of Tasmanian rainfall. Australian Meteorological Magazine 44: 261-274. 153. Rutherfurd, I., Abernethy, B. & Prosser, I., 1999. Stream erosion. In Lovett, S. & Price, P. (eds.), Riparian land management technical guidelines. Volume one: Principles of sound management. LWRRDC, Canberra, pp. 61-78. 154. Wolman, M. G. & Miller, J. P., 1960. Magnitude and frequency of forces in geomorphic processes. Journal of Geology 68: 54-74. 155. McMahon, T. A., 1982. World Hydrology: Does Australia fit? Hydrology and Water Resources Symposium, Melbourne. Institution of Engineers, pp. 1-7. 156. Baker, V. B., 1977. Stream channel response to floods, with examples from central Texas. Geological Society of America Bulletin 88: 1057-1071. 157. Nanson, G. C. & Doyle, C., 1999. Landscape stability, Quaternary climate change and European degradation of coastal rivers in southeastern Australia. In Rutherfurd, I. D. & Bartley, R. (eds.), Second Australian Stream Management Conference, Adelaide. Cooperative Research Centre for Catchment Hydrology, pp. 473-479. 158. Anon (ed.) Proceedings of the first CLIMANZ Conference, Howmans Gap, Victoria, Australia , 1981. 159. Goede, A., 1965. Geomorphology of the Buckland Basin, Tasmania. Papers and Proceedings of the Royal Society of Tasmania 99: 133-156. 160. Colhoun, E. A., 2002. Periglacial landforms and deposits of Tasmania. South African Journal of Science 98: 55-63. 161. Nanson, G., Barbetti, M. & Taylor, G., 1995. River stabilisation due to changing climate and vegetation during the late Quaternarty in western Tasmania. Geomorphology 13: 145-158. 162. Colhoun, E., Hannan, D. & Kiernan, K., 1996. Late Wisconsin glaciation of Tasmania. Papers and Proceedings of the Royal Society of Tasmania 130(2): 33-45. 163. Kiernan, K., 1990. The extent of late Cenozoic glaciation in the central highlands of Tasmania. Arctic and Alpine Research 22(4): 341-354. 164. Davies, J. L., 1971. Tasmanian landforms and quaternary climates. In Jennings, J. N. & Mabbutt, J. A. (eds.), Landform Studies from Australia and New Guinea. Australian National University Press, Canberra, Australia, pp. 1-25.

124 References cited

165. Williams, M., Dunkerley, D., De Decker, P., Kershaw, P. & Chappell, J., 1998. Quaternary Evnironments. Arnold, London. 166. Colhoun, E. A., 1989. Quaternary. In Burrett, C. F. & Martin, E. L. (eds.), Geology and mineral resources of Tasmania. Geological society of Australia, Hobart. 167. Colhoun, E. A., 1981. The climate of Tasmania 18 +/- 2 ka. Proceedings of the first CLIMANZ Conference,, Howmans Gap, Victoria, Australia. Australian National University. 168. McIntosh, P., 2001. Subsurface stream channels in dolerite talus, Forest Practices News, Hobart, Tasmania, Australia 169. Colhoun, E. A. & Peterson, J. A., 1986. Quaternary landscape evolution and the cryosophere: research progress from Sahul to Australian Antarctic. Australian Geographical Studies 24: 145-167. 170. Prosser, I. P., Hughes, A. O. & Rutherfurd, I. D., 2000. Bank erosion of an incised upland channel by subaerial processes: Tasmania, Australia. Earth Surface Processes and Landforms 25: 1085-1101. 171. Pemberton, M., 1986. Land systems of Tasmania. Region 5 - Central Plateau. Department of Agriculture, Hobart 172. Williams, M. A. J., Dunkerley, D. L., DeDeckker, P., Kershaw, A. P. & Stokes, T., 1993. Quaternary Environments. John Wiley & Sons. 173. Schumm, S. A., 1985. Patterns of alluvial rivers. Annual Review of Earth and Planetary Sciences 13: 5-27. 174. Epstein, C. M., 2002. Application of Rosgen Analysis to the New Jersey Pine Barrens. Journal of the American Water Resources Association 38(1): 69-78. 175. Holden, J., Burt, T. P. & Vilas, M., 2002. Application of ground-penetrating radar to the identification of subsurface piping in blanket peat. Earth Surface Processes and Landforms 27: 235-249. 176. Conway, V. M. & Millar, A., 1960. The hydrology of some small peat-covered catchments in the northern Pennines. Journal of the Institution of Water Engineers 14(6): 415-424. 177. Tarvydas, R. K., 1978. Lower Gordon Scientific Survey: Soils. The Hydro-Electric Commission, Tasmania, Hobart 178. Personal communication from Sib Corbett, 179. Goede, A., 1969. Underground stream capture at Ida Bay, Tasmania, and the relevance of cold climatic conditions. Australian Geographical Studies 7: 41-48. 180. Hickin, E. J., 1984. Vegetation and channel dynamics. The Canadian Geographer 28(2): 111-126. 181. Abernethy, B. & Rutherfurd, I. D., 1998. Where along a river's length will vegetation most effectively stabilise stream banks? Geomorphology 23: 55-75. 182. Chow, V. T., 1959. Open-Channel Hydraulics. McGraw-Hill, New York. 183. Watts, J. F. & Watts, G. D., 1990. Seasonal change in aquatic vegetation and its effect on river channel flow. In Thornes, J. B. (ed.), Vegetation and erosion: processes and environments. John Wiley & Sons, Chichester, UK, pp. 257-267. 184. Abernethy, B., 1999. On the role of woody vegetation in riverbank stability. PhD Thesis, Monash University, Melbourne. 185. Huang, H. Q. & Nanson, G. C., 1997. Vegetation and channel variation; a case study of four small streams in southeastern Australia. Geomorphology 18: 237-249. 186. Ikeda, S. & Izumi, N., 1990. Width and depth of self-formed straight gravel rivers with bank vegetation. Water Resources Research 26(10): 2353-2364. 187. Trimble, S. W., 1997. Stream channel erosion and change resulting from riparian forests. Geology 25(5): 467-469. 188. Montgomery, D. R., 1997. What's best on the banks? Nature 388: 328-329. 189. Gippel, C. J., O'Neill, I. C. & Finlayson, B. L., 1992. The hydraulic basis of snag management. Centre for Environmental Applied Hydrology, Melbourne. 190. Hupp, C. R. & Ostercamp, W. R., 1996. Riparian vegetation and fluvial geomorphic processes. Geomorphology 14: 277-295.

125 References cited

191. Goede, A., 1976. Provenance studies on Tambo River bedload deposits, eastern Victoria. Proceedings of the Royal Society of Victoria 88: 31-41. 192. Matthews, W. L., 1983. Geology and groundwater resources of the Longford Tertiary Basin. Geological Survey Bulletin 59. Department of Mines, Tasmania, Hobart 193. page 662 in Brierley, G. J. & Fryirs, K., 2000. River Styles, a geomorphic approach to catchment characteriszation: implications for river rehabilitation in Bega Catchment, New South Wales, Australia. Environmental Management 25(6): 661- 679. 194. Cohen, T. & Brierley, G., 1999. River Styles in the Hastings Basin, Mid North Coast, NSW. Macquarie University, Sydney 195. Goldrick, G., Brierley, G. & Fryirs, K., 1999. River Styles in the Richmond Catchment. NSW Department of Land and Water Conservation 196. Daniel, J. F., 1971. Channel movement of meandering Indiana streams. Geological Survey Professional Paper 732 - A. United States Geological Survey 197. Carson, M. A., 1984. Observations on the meandering-braided river transition, the Canterbury Plains, New Zealand: Part one. New Zealand Geographer 40: 12-19. 198. Brierley, G. J., 1989. River planform facies models: the sedimentology of braided, wandering and meandering reaches of the Squamish River, British Columbia. Sedimentary Geology 61: 17-35. 199. pages 2-3 in Brierley, G., Fryirs, K. & Cohen, T., 1996. Geomorphology & river ecology in southeastern Australia: an approach to catchment characterisation. Part One: A geomorphic approach to catchment characterisation. Working paper 9603. Graduate School of the Environment, Macquarie University, Sydney

126